glsl: move to compiler/

Signed-off-by: Emil Velikov <[email protected]>
Acked-by: Matt Turner <[email protected]>
Acked-by: Jose Fonseca <[email protected]>

1 files changed, 7583 insertions, 0 deletions

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
new file mode 100644
index 00000000000..dfd31966eb0
--- /dev/null
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -0,0 +1,7583 @@
+/*
+ * Copyright © 2010 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file ast_to_hir.c
+ * Convert abstract syntax to to high-level intermediate reprensentation (HIR).
+ *
+ * During the conversion to HIR, the majority of the symantic checking is
+ * preformed on the program.  This includes:
+ *
+ *    * Symbol table management
+ *    * Type checking
+ *    * Function binding
+ *
+ * The majority of this work could be done during parsing, and the parser could
+ * probably generate HIR directly.  However, this results in frequent changes
+ * to the parser code.  Since we do not assume that every system this complier
+ * is built on will have Flex and Bison installed, we have to store the code
+ * generated by these tools in our version control system.  In other parts of
+ * the system we've seen problems where a parser was changed but the generated
+ * code was not committed, merge conflicts where created because two developers
+ * had slightly different versions of Bison installed, etc.
+ *
+ * I have also noticed that running Bison generated parsers in GDB is very
+ * irritating.  When you get a segfault on '$$ = $1->foo', you can't very
+ * well 'print $1' in GDB.
+ *
+ * As a result, my preference is to put as little C code as possible in the
+ * parser (and lexer) sources.
+ */
+
+#include "glsl_symbol_table.h"
+#include "glsl_parser_extras.h"
+#include "ast.h"
+#include "compiler/glsl_types.h"
+#include "program/hash_table.h"
+#include "main/shaderobj.h"
+#include "ir.h"
+#include "ir_builder.h"
+
+using namespace ir_builder;
+
+static void
+detect_conflicting_assignments(struct _mesa_glsl_parse_state *state,
+			       exec_list *instructions);
+static void
+remove_per_vertex_blocks(exec_list *instructions,
+                         _mesa_glsl_parse_state *state, ir_variable_mode mode);
+
+/**
+ * Visitor class that finds the first instance of any write-only variable that
+ * is ever read, if any
+ */
+class read_from_write_only_variable_visitor : public ir_hierarchical_visitor
+{
+public:
+   read_from_write_only_variable_visitor() : found(NULL)
+   {
+   }
+
+   virtual ir_visitor_status visit(ir_dereference_variable *ir)
+   {
+      if (this->in_assignee)
+         return visit_continue;
+
+      ir_variable *var = ir->variable_referenced();
+      /* We can have image_write_only set on both images and buffer variables,
+       * but in the former there is a distinction between reads from
+       * the variable itself (write_only) and from the memory they point to
+       * (image_write_only), while in the case of buffer variables there is
+       * no such distinction, that is why this check here is limited to
+       * buffer variables alone.
+       */
+      if (!var || var->data.mode != ir_var_shader_storage)
+         return visit_continue;
+
+      if (var->data.image_write_only) {
+         found = var;
+         return visit_stop;
+      }
+
+      return visit_continue;
+   }
+
+   ir_variable *get_variable() {
+      return found;
+   }
+
+   virtual ir_visitor_status visit_enter(ir_expression *ir)
+   {
+      /* .length() doesn't actually read anything */
+      if (ir->operation == ir_unop_ssbo_unsized_array_length)
+         return visit_continue_with_parent;
+
+      return visit_continue;
+   }
+
+private:
+   ir_variable *found;
+};
+
+void
+_mesa_ast_to_hir(exec_list *instructions, struct _mesa_glsl_parse_state *state)
+{
+   _mesa_glsl_initialize_variables(instructions, state);
+
+   state->symbols->separate_function_namespace = state->language_version == 110;
+
+   state->current_function = NULL;
+
+   state->toplevel_ir = instructions;
+
+   state->gs_input_prim_type_specified = false;
+   state->tcs_output_vertices_specified = false;
+   state->cs_input_local_size_specified = false;
+
+   /* Section 4.2 of the GLSL 1.20 specification states:
+    * "The built-in functions are scoped in a scope outside the global scope
+    *  users declare global variables in.  That is, a shader's global scope,
+    *  available for user-defined functions and global variables, is nested
+    *  inside the scope containing the built-in functions."
+    *
+    * Since built-in functions like ftransform() access built-in variables,
+    * it follows that those must be in the outer scope as well.
+    *
+    * We push scope here to create this nesting effect...but don't pop.
+    * This way, a shader's globals are still in the symbol table for use
+    * by the linker.
+    */
+   state->symbols->push_scope();
+
+   foreach_list_typed (ast_node, ast, link, & state->translation_unit)
+      ast->hir(instructions, state);
+
+   detect_recursion_unlinked(state, instructions);
+   detect_conflicting_assignments(state, instructions);
+
+   state->toplevel_ir = NULL;
+
+   /* Move all of the variable declarations to the front of the IR list, and
+    * reverse the order.  This has the (intended!) side effect that vertex
+    * shader inputs and fragment shader outputs will appear in the IR in the
+    * same order that they appeared in the shader code.  This results in the
+    * locations being assigned in the declared order.  Many (arguably buggy)
+    * applications depend on this behavior, and it matches what nearly all
+    * other drivers do.
+    */
+   foreach_in_list_safe(ir_instruction, node, instructions) {
+      ir_variable *const var = node->as_variable();
+
+      if (var == NULL)
+         continue;
+
+      var->remove();
+      instructions->push_head(var);
+   }
+
+   /* Figure out if gl_FragCoord is actually used in fragment shader */
+   ir_variable *const var = state->symbols->get_variable("gl_FragCoord");
+   if (var != NULL)
+      state->fs_uses_gl_fragcoord = var->data.used;
+
+   /* From section 7.1 (Built-In Language Variables) of the GLSL 4.10 spec:
+    *
+    *     If multiple shaders using members of a built-in block belonging to
+    *     the same interface are linked together in the same program, they
+    *     must all redeclare the built-in block in the same way, as described
+    *     in section 4.3.7 "Interface Blocks" for interface block matching, or
+    *     a link error will result.
+    *
+    * The phrase "using members of a built-in block" implies that if two
+    * shaders are linked together and one of them *does not use* any members
+    * of the built-in block, then that shader does not need to have a matching
+    * redeclaration of the built-in block.
+    *
+    * This appears to be a clarification to the behaviour established for
+    * gl_PerVertex by GLSL 1.50, therefore implement it regardless of GLSL
+    * version.
+    *
+    * The definition of "interface" in section 4.3.7 that applies here is as
+    * follows:
+    *
+    *     The boundary between adjacent programmable pipeline stages: This
+    *     spans all the outputs in all compilation units of the first stage
+    *     and all the inputs in all compilation units of the second stage.
+    *
+    * Therefore this rule applies to both inter- and intra-stage linking.
+    *
+    * The easiest way to implement this is to check whether the shader uses
+    * gl_PerVertex right after ast-to-ir conversion, and if it doesn't, simply
+    * remove all the relevant variable declaration from the IR, so that the
+    * linker won't see them and complain about mismatches.
+    */
+   remove_per_vertex_blocks(instructions, state, ir_var_shader_in);
+   remove_per_vertex_blocks(instructions, state, ir_var_shader_out);
+
+   /* Check that we don't have reads from write-only variables */
+   read_from_write_only_variable_visitor v;
+   v.run(instructions);
+   ir_variable *error_var = v.get_variable();
+   if (error_var) {
+      /* It would be nice to have proper location information, but for that
+       * we would need to check this as we process each kind of AST node
+       */
+      YYLTYPE loc;
+      memset(&loc, 0, sizeof(loc));
+      _mesa_glsl_error(&loc, state, "Read from write-only variable `%s'",
+                       error_var->name);
+   }
+}
+
+
+static ir_expression_operation
+get_conversion_operation(const glsl_type *to, const glsl_type *from,
+                         struct _mesa_glsl_parse_state *state)
+{
+   switch (to->base_type) {
+   case GLSL_TYPE_FLOAT:
+      switch (from->base_type) {
+      case GLSL_TYPE_INT: return ir_unop_i2f;
+      case GLSL_TYPE_UINT: return ir_unop_u2f;
+      case GLSL_TYPE_DOUBLE: return ir_unop_d2f;
+      default: return (ir_expression_operation)0;
+      }
+
+   case GLSL_TYPE_UINT:
+      if (!state->is_version(400, 0) && !state->ARB_gpu_shader5_enable)
+         return (ir_expression_operation)0;
+      switch (from->base_type) {
+         case GLSL_TYPE_INT: return ir_unop_i2u;
+         default: return (ir_expression_operation)0;
+      }
+
+   case GLSL_TYPE_DOUBLE:
+      if (!state->has_double())
+         return (ir_expression_operation)0;
+      switch (from->base_type) {
+      case GLSL_TYPE_INT: return ir_unop_i2d;
+      case GLSL_TYPE_UINT: return ir_unop_u2d;
+      case GLSL_TYPE_FLOAT: return ir_unop_f2d;
+      default: return (ir_expression_operation)0;
+      }
+
+   default: return (ir_expression_operation)0;
+   }
+}
+
+
+/**
+ * If a conversion is available, convert one operand to a different type
+ *
+ * The \c from \c ir_rvalue is converted "in place".
+ *
+ * \param to     Type that the operand it to be converted to
+ * \param from   Operand that is being converted
+ * \param state  GLSL compiler state
+ *
+ * \return
+ * If a conversion is possible (or unnecessary), \c true is returned.
+ * Otherwise \c false is returned.
+ */
+bool
+apply_implicit_conversion(const glsl_type *to, ir_rvalue * &from,
+                          struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = state;
+   if (to->base_type == from->type->base_type)
+      return true;
+
+   /* Prior to GLSL 1.20, there are no implicit conversions */
+   if (!state->is_version(120, 0))
+      return false;
+
+   /* From page 27 (page 33 of the PDF) of the GLSL 1.50 spec:
+    *
+    *    "There are no implicit array or structure conversions. For
+    *    example, an array of int cannot be implicitly converted to an
+    *    array of float.
+    */
+   if (!to->is_numeric() || !from->type->is_numeric())
+      return false;
+
+   /* We don't actually want the specific type `to`, we want a type
+    * with the same base type as `to`, but the same vector width as
+    * `from`.
+    */
+   to = glsl_type::get_instance(to->base_type, from->type->vector_elements,
+                                from->type->matrix_columns);
+
+   ir_expression_operation op = get_conversion_operation(to, from->type, state);
+   if (op) {
+      from = new(ctx) ir_expression(op, to, from, NULL);
+      return true;
+   } else {
+      return false;
+   }
+}
+
+
+static const struct glsl_type *
+arithmetic_result_type(ir_rvalue * &value_a, ir_rvalue * &value_b,
+                       bool multiply,
+                       struct _mesa_glsl_parse_state *state, YYLTYPE *loc)
+{
+   const glsl_type *type_a = value_a->type;
+   const glsl_type *type_b = value_b->type;
+
+   /* From GLSL 1.50 spec, page 56:
+    *
+    *    "The arithmetic binary operators add (+), subtract (-),
+    *    multiply (*), and divide (/) operate on integer and
+    *    floating-point scalars, vectors, and matrices."
+    */
+   if (!type_a->is_numeric() || !type_b->is_numeric()) {
+      _mesa_glsl_error(loc, state,
+                       "operands to arithmetic operators must be numeric");
+      return glsl_type::error_type;
+   }
+
+
+   /*    "If one operand is floating-point based and the other is
+    *    not, then the conversions from Section 4.1.10 "Implicit
+    *    Conversions" are applied to the non-floating-point-based operand."
+    */
+   if (!apply_implicit_conversion(type_a, value_b, state)
+       && !apply_implicit_conversion(type_b, value_a, state)) {
+      _mesa_glsl_error(loc, state,
+                       "could not implicitly convert operands to "
+                       "arithmetic operator");
+      return glsl_type::error_type;
+   }
+   type_a = value_a->type;
+   type_b = value_b->type;
+
+   /*    "If the operands are integer types, they must both be signed or
+    *    both be unsigned."
+    *
+    * From this rule and the preceeding conversion it can be inferred that
+    * both types must be GLSL_TYPE_FLOAT, or GLSL_TYPE_UINT, or GLSL_TYPE_INT.
+    * The is_numeric check above already filtered out the case where either
+    * type is not one of these, so now the base types need only be tested for
+    * equality.
+    */
+   if (type_a->base_type != type_b->base_type) {
+      _mesa_glsl_error(loc, state,
+                       "base type mismatch for arithmetic operator");
+      return glsl_type::error_type;
+   }
+
+   /*    "All arithmetic binary operators result in the same fundamental type
+    *    (signed integer, unsigned integer, or floating-point) as the
+    *    operands they operate on, after operand type conversion. After
+    *    conversion, the following cases are valid
+    *
+    *    * The two operands are scalars. In this case the operation is
+    *      applied, resulting in a scalar."
+    */
+   if (type_a->is_scalar() && type_b->is_scalar())
+      return type_a;
+
+   /*   "* One operand is a scalar, and the other is a vector or matrix.
+    *      In this case, the scalar operation is applied independently to each
+    *      component of the vector or matrix, resulting in the same size
+    *      vector or matrix."
+    */
+   if (type_a->is_scalar()) {
+      if (!type_b->is_scalar())
+         return type_b;
+   } else if (type_b->is_scalar()) {
+      return type_a;
+   }
+
+   /* All of the combinations of <scalar, scalar>, <vector, scalar>,
+    * <scalar, vector>, <scalar, matrix>, and <matrix, scalar> have been
+    * handled.
+    */
+   assert(!type_a->is_scalar());
+   assert(!type_b->is_scalar());
+
+   /*   "* The two operands are vectors of the same size. In this case, the
+    *      operation is done component-wise resulting in the same size
+    *      vector."
+    */
+   if (type_a->is_vector() && type_b->is_vector()) {
+      if (type_a == type_b) {
+         return type_a;
+      } else {
+         _mesa_glsl_error(loc, state,
+                          "vector size mismatch for arithmetic operator");
+         return glsl_type::error_type;
+      }
+   }
+
+   /* All of the combinations of <scalar, scalar>, <vector, scalar>,
+    * <scalar, vector>, <scalar, matrix>, <matrix, scalar>, and
+    * <vector, vector> have been handled.  At least one of the operands must
+    * be matrix.  Further, since there are no integer matrix types, the base
+    * type of both operands must be float.
+    */
+   assert(type_a->is_matrix() || type_b->is_matrix());
+   assert(type_a->base_type == GLSL_TYPE_FLOAT ||
+          type_a->base_type == GLSL_TYPE_DOUBLE);
+   assert(type_b->base_type == GLSL_TYPE_FLOAT ||
+          type_b->base_type == GLSL_TYPE_DOUBLE);
+
+   /*   "* The operator is add (+), subtract (-), or divide (/), and the
+    *      operands are matrices with the same number of rows and the same
+    *      number of columns. In this case, the operation is done component-
+    *      wise resulting in the same size matrix."
+    *    * The operator is multiply (*), where both operands are matrices or
+    *      one operand is a vector and the other a matrix. A right vector
+    *      operand is treated as a column vector and a left vector operand as a
+    *      row vector. In all these cases, it is required that the number of
+    *      columns of the left operand is equal to the number of rows of the
+    *      right operand. Then, the multiply (*) operation does a linear
+    *      algebraic multiply, yielding an object that has the same number of
+    *      rows as the left operand and the same number of columns as the right
+    *      operand. Section 5.10 "Vector and Matrix Operations" explains in
+    *      more detail how vectors and matrices are operated on."
+    */
+   if (! multiply) {
+      if (type_a == type_b)
+         return type_a;
+   } else {
+      const glsl_type *type = glsl_type::get_mul_type(type_a, type_b);
+
+      if (type == glsl_type::error_type) {
+         _mesa_glsl_error(loc, state,
+                          "size mismatch for matrix multiplication");
+      }
+
+      return type;
+   }
+
+
+   /*    "All other cases are illegal."
+    */
+   _mesa_glsl_error(loc, state, "type mismatch");
+   return glsl_type::error_type;
+}
+
+
+static const struct glsl_type *
+unary_arithmetic_result_type(const struct glsl_type *type,
+                             struct _mesa_glsl_parse_state *state, YYLTYPE *loc)
+{
+   /* From GLSL 1.50 spec, page 57:
+    *
+    *    "The arithmetic unary operators negate (-), post- and pre-increment
+    *     and decrement (-- and ++) operate on integer or floating-point
+    *     values (including vectors and matrices). All unary operators work
+    *     component-wise on their operands. These result with the same type
+    *     they operated on."
+    */
+   if (!type->is_numeric()) {
+      _mesa_glsl_error(loc, state,
+                       "operands to arithmetic operators must be numeric");
+      return glsl_type::error_type;
+   }
+
+   return type;
+}
+
+/**
+ * \brief Return the result type of a bit-logic operation.
+ *
+ * If the given types to the bit-logic operator are invalid, return
+ * glsl_type::error_type.
+ *
+ * \param value_a LHS of bit-logic op
+ * \param value_b RHS of bit-logic op
+ */
+static const struct glsl_type *
+bit_logic_result_type(ir_rvalue * &value_a, ir_rvalue * &value_b,
+                      ast_operators op,
+                      struct _mesa_glsl_parse_state *state, YYLTYPE *loc)
+{
+   const glsl_type *type_a = value_a->type;
+   const glsl_type *type_b = value_b->type;
+
+   if (!state->check_bitwise_operations_allowed(loc)) {
+      return glsl_type::error_type;
+   }
+
+   /* From page 50 (page 56 of PDF) of GLSL 1.30 spec:
+    *
+    *     "The bitwise operators and (&), exclusive-or (^), and inclusive-or
+    *     (|). The operands must be of type signed or unsigned integers or
+    *     integer vectors."
+    */
+   if (!type_a->is_integer()) {
+      _mesa_glsl_error(loc, state, "LHS of `%s' must be an integer",
+                        ast_expression::operator_string(op));
+      return glsl_type::error_type;
+   }
+   if (!type_b->is_integer()) {
+      _mesa_glsl_error(loc, state, "RHS of `%s' must be an integer",
+                       ast_expression::operator_string(op));
+      return glsl_type::error_type;
+   }
+
+   /* Prior to GLSL 4.0 / GL_ARB_gpu_shader5, implicit conversions didn't
+    * make sense for bitwise operations, as they don't operate on floats.
+    *
+    * GLSL 4.0 added implicit int -> uint conversions, which are relevant
+    * here.  It wasn't clear whether or not we should apply them to bitwise
+    * operations.  However, Khronos has decided that they should in future
+    * language revisions.  Applications also rely on this behavior.  We opt
+    * to apply them in general, but issue a portability warning.
+    *
+    * See https://www.khronos.org/bugzilla/show_bug.cgi?id=1405
+    */
+   if (type_a->base_type != type_b->base_type) {
+      if (!apply_implicit_conversion(type_a, value_b, state)
+          && !apply_implicit_conversion(type_b, value_a, state)) {
+         _mesa_glsl_error(loc, state,
+                          "could not implicitly convert operands to "
+                          "`%s` operator",
+                          ast_expression::operator_string(op));
+         return glsl_type::error_type;
+      } else {
+         _mesa_glsl_warning(loc, state,
+                            "some implementations may not support implicit "
+                            "int -> uint conversions for `%s' operators; "
+                            "consider casting explicitly for portability",
+                            ast_expression::operator_string(op));
+      }
+      type_a = value_a->type;
+      type_b = value_b->type;
+   }
+
+   /*     "The fundamental types of the operands (signed or unsigned) must
+    *     match,"
+    */
+   if (type_a->base_type != type_b->base_type) {
+      _mesa_glsl_error(loc, state, "operands of `%s' must have the same "
+                       "base type", ast_expression::operator_string(op));
+      return glsl_type::error_type;
+   }
+
+   /*     "The operands cannot be vectors of differing size." */
+   if (type_a->is_vector() &&
+       type_b->is_vector() &&
+       type_a->vector_elements != type_b->vector_elements) {
+      _mesa_glsl_error(loc, state, "operands of `%s' cannot be vectors of "
+                       "different sizes", ast_expression::operator_string(op));
+      return glsl_type::error_type;
+   }
+
+   /*     "If one operand is a scalar and the other a vector, the scalar is
+    *     applied component-wise to the vector, resulting in the same type as
+    *     the vector. The fundamental types of the operands [...] will be the
+    *     resulting fundamental type."
+    */
+   if (type_a->is_scalar())
+       return type_b;
+   else
+       return type_a;
+}
+
+static const struct glsl_type *
+modulus_result_type(ir_rvalue * &value_a, ir_rvalue * &value_b,
+                    struct _mesa_glsl_parse_state *state, YYLTYPE *loc)
+{
+   const glsl_type *type_a = value_a->type;
+   const glsl_type *type_b = value_b->type;
+
+   if (!state->check_version(130, 300, loc, "operator '%%' is reserved")) {
+      return glsl_type::error_type;
+   }
+
+   /* Section 5.9 (Expressions) of the GLSL 4.00 specification says:
+    *
+    *    "The operator modulus (%) operates on signed or unsigned integers or
+    *    integer vectors."
+    */
+   if (!type_a->is_integer()) {
+      _mesa_glsl_error(loc, state, "LHS of operator %% must be an integer");
+      return glsl_type::error_type;
+   }
+   if (!type_b->is_integer()) {
+      _mesa_glsl_error(loc, state, "RHS of operator %% must be an integer");
+      return glsl_type::error_type;
+   }
+
+   /*    "If the fundamental types in the operands do not match, then the
+    *    conversions from section 4.1.10 "Implicit Conversions" are applied
+    *    to create matching types."
+    *
+    * Note that GLSL 4.00 (and GL_ARB_gpu_shader5) introduced implicit
+    * int -> uint conversion rules.  Prior to that, there were no implicit
+    * conversions.  So it's harmless to apply them universally - no implicit
+    * conversions will exist.  If the types don't match, we'll receive false,
+    * and raise an error, satisfying the GLSL 1.50 spec, page 56:
+    *
+    *    "The operand types must both be signed or unsigned."
+    */
+   if (!apply_implicit_conversion(type_a, value_b, state) &&
+       !apply_implicit_conversion(type_b, value_a, state)) {
+      _mesa_glsl_error(loc, state,
+                       "could not implicitly convert operands to "
+                       "modulus (%%) operator");
+      return glsl_type::error_type;
+   }
+   type_a = value_a->type;
+   type_b = value_b->type;
+
+   /*    "The operands cannot be vectors of differing size. If one operand is
+    *    a scalar and the other vector, then the scalar is applied component-
+    *    wise to the vector, resulting in the same type as the vector. If both
+    *    are vectors of the same size, the result is computed component-wise."
+    */
+   if (type_a->is_vector()) {
+      if (!type_b->is_vector()
+          || (type_a->vector_elements == type_b->vector_elements))
+      return type_a;
+   } else
+      return type_b;
+
+   /*    "The operator modulus (%) is not defined for any other data types
+    *    (non-integer types)."
+    */
+   _mesa_glsl_error(loc, state, "type mismatch");
+   return glsl_type::error_type;
+}
+
+
+static const struct glsl_type *
+relational_result_type(ir_rvalue * &value_a, ir_rvalue * &value_b,
+                       struct _mesa_glsl_parse_state *state, YYLTYPE *loc)
+{
+   const glsl_type *type_a = value_a->type;
+   const glsl_type *type_b = value_b->type;
+
+   /* From GLSL 1.50 spec, page 56:
+    *    "The relational operators greater than (>), less than (<), greater
+    *    than or equal (>=), and less than or equal (<=) operate only on
+    *    scalar integer and scalar floating-point expressions."
+    */
+   if (!type_a->is_numeric()
+       || !type_b->is_numeric()
+       || !type_a->is_scalar()
+       || !type_b->is_scalar()) {
+      _mesa_glsl_error(loc, state,
+                       "operands to relational operators must be scalar and "
+                       "numeric");
+      return glsl_type::error_type;
+   }
+
+   /*    "Either the operands' types must match, or the conversions from
+    *    Section 4.1.10 "Implicit Conversions" will be applied to the integer
+    *    operand, after which the types must match."
+    */
+   if (!apply_implicit_conversion(type_a, value_b, state)
+       && !apply_implicit_conversion(type_b, value_a, state)) {
+      _mesa_glsl_error(loc, state,
+                       "could not implicitly convert operands to "
+                       "relational operator");
+      return glsl_type::error_type;
+   }
+   type_a = value_a->type;
+   type_b = value_b->type;
+
+   if (type_a->base_type != type_b->base_type) {
+      _mesa_glsl_error(loc, state, "base type mismatch");
+      return glsl_type::error_type;
+   }
+
+   /*    "The result is scalar Boolean."
+    */
+   return glsl_type::bool_type;
+}
+
+/**
+ * \brief Return the result type of a bit-shift operation.
+ *
+ * If the given types to the bit-shift operator are invalid, return
+ * glsl_type::error_type.
+ *
+ * \param type_a Type of LHS of bit-shift op
+ * \param type_b Type of RHS of bit-shift op
+ */
+static const struct glsl_type *
+shift_result_type(const struct glsl_type *type_a,
+                  const struct glsl_type *type_b,
+                  ast_operators op,
+                  struct _mesa_glsl_parse_state *state, YYLTYPE *loc)
+{
+   if (!state->check_bitwise_operations_allowed(loc)) {
+      return glsl_type::error_type;
+   }
+
+   /* From page 50 (page 56 of the PDF) of the GLSL 1.30 spec:
+    *
+    *     "The shift operators (<<) and (>>). For both operators, the operands
+    *     must be signed or unsigned integers or integer vectors. One operand
+    *     can be signed while the other is unsigned."
+    */
+   if (!type_a->is_integer()) {
+      _mesa_glsl_error(loc, state, "LHS of operator %s must be an integer or "
+                       "integer vector", ast_expression::operator_string(op));
+     return glsl_type::error_type;
+
+   }
+   if (!type_b->is_integer()) {
+      _mesa_glsl_error(loc, state, "RHS of operator %s must be an integer or "
+                       "integer vector", ast_expression::operator_string(op));
+     return glsl_type::error_type;
+   }
+
+   /*     "If the first operand is a scalar, the second operand has to be
+    *     a scalar as well."
+    */
+   if (type_a->is_scalar() && !type_b->is_scalar()) {
+      _mesa_glsl_error(loc, state, "if the first operand of %s is scalar, the "
+                       "second must be scalar as well",
+                       ast_expression::operator_string(op));
+     return glsl_type::error_type;
+   }
+
+   /* If both operands are vectors, check that they have same number of
+    * elements.
+    */
+   if (type_a->is_vector() &&
+      type_b->is_vector() &&
+      type_a->vector_elements != type_b->vector_elements) {
+      _mesa_glsl_error(loc, state, "vector operands to operator %s must "
+                       "have same number of elements",
+                       ast_expression::operator_string(op));
+     return glsl_type::error_type;
+   }
+
+   /*     "In all cases, the resulting type will be the same type as the left
+    *     operand."
+    */
+   return type_a;
+}
+
+/**
+ * Returns the innermost array index expression in an rvalue tree.
+ * This is the largest indexing level -- if an array of blocks, then
+ * it is the block index rather than an indexing expression for an
+ * array-typed member of an array of blocks.
+ */
+static ir_rvalue *
+find_innermost_array_index(ir_rvalue *rv)
+{
+   ir_dereference_array *last = NULL;
+   while (rv) {
+      if (rv->as_dereference_array()) {
+         last = rv->as_dereference_array();
+         rv = last->array;
+      } else if (rv->as_dereference_record())
+         rv = rv->as_dereference_record()->record;
+      else if (rv->as_swizzle())
+         rv = rv->as_swizzle()->val;
+      else
+         rv = NULL;
+   }
+
+   if (last)
+      return last->array_index;
+
+   return NULL;
+}
+
+/**
+ * Validates that a value can be assigned to a location with a specified type
+ *
+ * Validates that \c rhs can be assigned to some location.  If the types are
+ * not an exact match but an automatic conversion is possible, \c rhs will be
+ * converted.
+ *
+ * \return
+ * \c NULL if \c rhs cannot be assigned to a location with type \c lhs_type.
+ * Otherwise the actual RHS to be assigned will be returned.  This may be
+ * \c rhs, or it may be \c rhs after some type conversion.
+ *
+ * \note
+ * In addition to being used for assignments, this function is used to
+ * type-check return values.
+ */
+static ir_rvalue *
+validate_assignment(struct _mesa_glsl_parse_state *state,
+                    YYLTYPE loc, ir_rvalue *lhs,
+                    ir_rvalue *rhs, bool is_initializer)
+{
+   /* If there is already some error in the RHS, just return it.  Anything
+    * else will lead to an avalanche of error message back to the user.
+    */
+   if (rhs->type->is_error())
+      return rhs;
+
+   /* In the Tessellation Control Shader:
+    * If a per-vertex output variable is used as an l-value, it is an error
+    * if the expression indicating the vertex number is not the identifier
+    * `gl_InvocationID`.
+    */
+   if (state->stage == MESA_SHADER_TESS_CTRL) {
+      ir_variable *var = lhs->variable_referenced();
+      if (var->data.mode == ir_var_shader_out && !var->data.patch) {
+         ir_rvalue *index = find_innermost_array_index(lhs);
+         ir_variable *index_var = index ? index->variable_referenced() : NULL;
+         if (!index_var || strcmp(index_var->name, "gl_InvocationID") != 0) {
+            _mesa_glsl_error(&loc, state,
+                             "Tessellation control shader outputs can only "
+                             "be indexed by gl_InvocationID");
+            return NULL;
+         }
+      }
+   }
+
+   /* If the types are identical, the assignment can trivially proceed.
+    */
+   if (rhs->type == lhs->type)
+      return rhs;
+
+   /* If the array element types are the same and the LHS is unsized,
+    * the assignment is okay for initializers embedded in variable
+    * declarations.
+    *
+    * Note: Whole-array assignments are not permitted in GLSL 1.10, but this
+    * is handled by ir_dereference::is_lvalue.
+    */
+   const glsl_type *lhs_t = lhs->type;
+   const glsl_type *rhs_t = rhs->type;
+   bool unsized_array = false;
+   while(lhs_t->is_array()) {
+      if (rhs_t == lhs_t)
+         break; /* the rest of the inner arrays match so break out early */
+      if (!rhs_t->is_array()) {
+         unsized_array = false;
+         break; /* number of dimensions mismatch */
+      }
+      if (lhs_t->length == rhs_t->length) {
+         lhs_t = lhs_t->fields.array;
+         rhs_t = rhs_t->fields.array;
+         continue;
+      } else if (lhs_t->is_unsized_array()) {
+         unsized_array = true;
+      } else {
+         unsized_array = false;
+         break; /* sized array mismatch */
+      }
+      lhs_t = lhs_t->fields.array;
+      rhs_t = rhs_t->fields.array;
+   }
+   if (unsized_array) {
+      if (is_initializer) {
+         return rhs;
+      } else {
+         _mesa_glsl_error(&loc, state,
+                          "implicitly sized arrays cannot be assigned");
+         return NULL;
+      }
+   }
+
+   /* Check for implicit conversion in GLSL 1.20 */
+   if (apply_implicit_conversion(lhs->type, rhs, state)) {
+      if (rhs->type == lhs->type)
+	 return rhs;
+   }
+
+   _mesa_glsl_error(&loc, state,
+                    "%s of type %s cannot be assigned to "
+                    "variable of type %s",
+                    is_initializer ? "initializer" : "value",
+                    rhs->type->name, lhs->type->name);
+
+   return NULL;
+}
+
+static void
+mark_whole_array_access(ir_rvalue *access)
+{
+   ir_dereference_variable *deref = access->as_dereference_variable();
+
+   if (deref && deref->var) {
+      deref->var->data.max_array_access = deref->type->length - 1;
+   }
+}
+
+static bool
+do_assignment(exec_list *instructions, struct _mesa_glsl_parse_state *state,
+              const char *non_lvalue_description,
+              ir_rvalue *lhs, ir_rvalue *rhs,
+              ir_rvalue **out_rvalue, bool needs_rvalue,
+              bool is_initializer,
+              YYLTYPE lhs_loc)
+{
+   void *ctx = state;
+   bool error_emitted = (lhs->type->is_error() || rhs->type->is_error());
+
+   ir_variable *lhs_var = lhs->variable_referenced();
+   if (lhs_var)
+      lhs_var->data.assigned = true;
+
+   if (!error_emitted) {
+      if (non_lvalue_description != NULL) {
+         _mesa_glsl_error(&lhs_loc, state,
+                          "assignment to %s",
+                          non_lvalue_description);
+         error_emitted = true;
+      } else if (lhs_var != NULL && (lhs_var->data.read_only ||
+                 (lhs_var->data.mode == ir_var_shader_storage &&
+                  lhs_var->data.image_read_only))) {
+         /* We can have image_read_only set on both images and buffer variables,
+          * but in the former there is a distinction between assignments to
+          * the variable itself (read_only) and to the memory they point to
+          * (image_read_only), while in the case of buffer variables there is
+          * no such distinction, that is why this check here is limited to
+          * buffer variables alone.
+          */
+         _mesa_glsl_error(&lhs_loc, state,
+                          "assignment to read-only variable '%s'",
+                          lhs_var->name);
+         error_emitted = true;
+      } else if (lhs->type->is_array() &&
+                 !state->check_version(120, 300, &lhs_loc,
+                                       "whole array assignment forbidden")) {
+         /* From page 32 (page 38 of the PDF) of the GLSL 1.10 spec:
+          *
+          *    "Other binary or unary expressions, non-dereferenced
+          *     arrays, function names, swizzles with repeated fields,
+          *     and constants cannot be l-values."
+          *
+          * The restriction on arrays is lifted in GLSL 1.20 and GLSL ES 3.00.
+          */
+         error_emitted = true;
+      } else if (!lhs->is_lvalue()) {
+         _mesa_glsl_error(& lhs_loc, state, "non-lvalue in assignment");
+         error_emitted = true;
+      }
+   }
+
+   ir_rvalue *new_rhs =
+      validate_assignment(state, lhs_loc, lhs, rhs, is_initializer);
+   if (new_rhs != NULL) {
+      rhs = new_rhs;
+
+      /* If the LHS array was not declared with a size, it takes it size from
+       * the RHS.  If the LHS is an l-value and a whole array, it must be a
+       * dereference of a variable.  Any other case would require that the LHS
+       * is either not an l-value or not a whole array.
+       */
+      if (lhs->type->is_unsized_array()) {
+         ir_dereference *const d = lhs->as_dereference();
+
+         assert(d != NULL);
+
+         ir_variable *const var = d->variable_referenced();
+
+         assert(var != NULL);
+
+         if (var->data.max_array_access >= unsigned(rhs->type->array_size())) {
+            /* FINISHME: This should actually log the location of the RHS. */
+            _mesa_glsl_error(& lhs_loc, state, "array size must be > %u due to "
+                             "previous access",
+                             var->data.max_array_access);
+         }
+
+         var->type = glsl_type::get_array_instance(lhs->type->fields.array,
+                                                   rhs->type->array_size());
+         d->type = var->type;
+      }
+      if (lhs->type->is_array()) {
+         mark_whole_array_access(rhs);
+         mark_whole_array_access(lhs);
+      }
+   }
+
+   /* Most callers of do_assignment (assign, add_assign, pre_inc/dec,
+    * but not post_inc) need the converted assigned value as an rvalue
+    * to handle things like:
+    *
+    * i = j += 1;
+    */
+   if (needs_rvalue) {
+      ir_variable *var = new(ctx) ir_variable(rhs->type, "assignment_tmp",
+                                              ir_var_temporary);
+      instructions->push_tail(var);
+      instructions->push_tail(assign(var, rhs));
+
+      if (!error_emitted) {
+         ir_dereference_variable *deref_var = new(ctx) ir_dereference_variable(var);
+         instructions->push_tail(new(ctx) ir_assignment(lhs, deref_var));
+      }
+      ir_rvalue *rvalue = new(ctx) ir_dereference_variable(var);
+
+      *out_rvalue = rvalue;
+   } else {
+      if (!error_emitted)
+         instructions->push_tail(new(ctx) ir_assignment(lhs, rhs));
+      *out_rvalue = NULL;
+   }
+
+   return error_emitted;
+}
+
+static ir_rvalue *
+get_lvalue_copy(exec_list *instructions, ir_rvalue *lvalue)
+{
+   void *ctx = ralloc_parent(lvalue);
+   ir_variable *var;
+
+   var = new(ctx) ir_variable(lvalue->type, "_post_incdec_tmp",
+			      ir_var_temporary);
+   instructions->push_tail(var);
+
+   instructions->push_tail(new(ctx) ir_assignment(new(ctx) ir_dereference_variable(var),
+						  lvalue));
+
+   return new(ctx) ir_dereference_variable(var);
+}
+
+
+ir_rvalue *
+ast_node::hir(exec_list *instructions, struct _mesa_glsl_parse_state *state)
+{
+   (void) instructions;
+   (void) state;
+
+   return NULL;
+}
+
+bool
+ast_node::has_sequence_subexpression() const
+{
+   return false;
+}
+
+void
+ast_function_expression::hir_no_rvalue(exec_list *instructions,
+                                       struct _mesa_glsl_parse_state *state)
+{
+   (void)hir(instructions, state);
+}
+
+void
+ast_aggregate_initializer::hir_no_rvalue(exec_list *instructions,
+                                         struct _mesa_glsl_parse_state *state)
+{
+   (void)hir(instructions, state);
+}
+
+static ir_rvalue *
+do_comparison(void *mem_ctx, int operation, ir_rvalue *op0, ir_rvalue *op1)
+{
+   int join_op;
+   ir_rvalue *cmp = NULL;
+
+   if (operation == ir_binop_all_equal)
+      join_op = ir_binop_logic_and;
+   else
+      join_op = ir_binop_logic_or;
+
+   switch (op0->type->base_type) {
+   case GLSL_TYPE_FLOAT:
+   case GLSL_TYPE_UINT:
+   case GLSL_TYPE_INT:
+   case GLSL_TYPE_BOOL:
+   case GLSL_TYPE_DOUBLE:
+      return new(mem_ctx) ir_expression(operation, op0, op1);
+
+   case GLSL_TYPE_ARRAY: {
+      for (unsigned int i = 0; i < op0->type->length; i++) {
+         ir_rvalue *e0, *e1, *result;
+
+         e0 = new(mem_ctx) ir_dereference_array(op0->clone(mem_ctx, NULL),
+                                                new(mem_ctx) ir_constant(i));
+         e1 = new(mem_ctx) ir_dereference_array(op1->clone(mem_ctx, NULL),
+                                                new(mem_ctx) ir_constant(i));
+         result = do_comparison(mem_ctx, operation, e0, e1);
+
+         if (cmp) {
+            cmp = new(mem_ctx) ir_expression(join_op, cmp, result);
+         } else {
+            cmp = result;
+         }
+      }
+
+      mark_whole_array_access(op0);
+      mark_whole_array_access(op1);
+      break;
+   }
+
+   case GLSL_TYPE_STRUCT: {
+      for (unsigned int i = 0; i < op0->type->length; i++) {
+         ir_rvalue *e0, *e1, *result;
+         const char *field_name = op0->type->fields.structure[i].name;
+
+         e0 = new(mem_ctx) ir_dereference_record(op0->clone(mem_ctx, NULL),
+                                                 field_name);
+         e1 = new(mem_ctx) ir_dereference_record(op1->clone(mem_ctx, NULL),
+                                                 field_name);
+         result = do_comparison(mem_ctx, operation, e0, e1);
+
+         if (cmp) {
+            cmp = new(mem_ctx) ir_expression(join_op, cmp, result);
+         } else {
+            cmp = result;
+         }
+      }
+      break;
+   }
+
+   case GLSL_TYPE_ERROR:
+   case GLSL_TYPE_VOID:
+   case GLSL_TYPE_SAMPLER:
+   case GLSL_TYPE_IMAGE:
+   case GLSL_TYPE_INTERFACE:
+   case GLSL_TYPE_ATOMIC_UINT:
+   case GLSL_TYPE_SUBROUTINE:
+      /* I assume a comparison of a struct containing a sampler just
+       * ignores the sampler present in the type.
+       */
+      break;
+   }
+
+   if (cmp == NULL)
+      cmp = new(mem_ctx) ir_constant(true);
+
+   return cmp;
+}
+
+/* For logical operations, we want to ensure that the operands are
+ * scalar booleans.  If it isn't, emit an error and return a constant
+ * boolean to avoid triggering cascading error messages.
+ */
+ir_rvalue *
+get_scalar_boolean_operand(exec_list *instructions,
+			   struct _mesa_glsl_parse_state *state,
+			   ast_expression *parent_expr,
+			   int operand,
+			   const char *operand_name,
+			   bool *error_emitted)
+{
+   ast_expression *expr = parent_expr->subexpressions[operand];
+   void *ctx = state;
+   ir_rvalue *val = expr->hir(instructions, state);
+
+   if (val->type->is_boolean() && val->type->is_scalar())
+      return val;
+
+   if (!*error_emitted) {
+      YYLTYPE loc = expr->get_location();
+      _mesa_glsl_error(&loc, state, "%s of `%s' must be scalar boolean",
+                       operand_name,
+                       parent_expr->operator_string(parent_expr->oper));
+      *error_emitted = true;
+   }
+
+   return new(ctx) ir_constant(true);
+}
+
+/**
+ * If name refers to a builtin array whose maximum allowed size is less than
+ * size, report an error and return true.  Otherwise return false.
+ */
+void
+check_builtin_array_max_size(const char *name, unsigned size,
+                             YYLTYPE loc, struct _mesa_glsl_parse_state *state)
+{
+   if ((strcmp("gl_TexCoord", name) == 0)
+       && (size > state->Const.MaxTextureCoords)) {
+      /* From page 54 (page 60 of the PDF) of the GLSL 1.20 spec:
+       *
+       *     "The size [of gl_TexCoord] can be at most
+       *     gl_MaxTextureCoords."
+       */
+      _mesa_glsl_error(&loc, state, "`gl_TexCoord' array size cannot "
+                       "be larger than gl_MaxTextureCoords (%u)",
+                       state->Const.MaxTextureCoords);
+   } else if (strcmp("gl_ClipDistance", name) == 0
+              && size > state->Const.MaxClipPlanes) {
+      /* From section 7.1 (Vertex Shader Special Variables) of the
+       * GLSL 1.30 spec:
+       *
+       *   "The gl_ClipDistance array is predeclared as unsized and
+       *   must be sized by the shader either redeclaring it with a
+       *   size or indexing it only with integral constant
+       *   expressions. ... The size can be at most
+       *   gl_MaxClipDistances."
+       */
+      _mesa_glsl_error(&loc, state, "`gl_ClipDistance' array size cannot "
+                       "be larger than gl_MaxClipDistances (%u)",
+                       state->Const.MaxClipPlanes);
+   }
+}
+
+/**
+ * Create the constant 1, of a which is appropriate for incrementing and
+ * decrementing values of the given GLSL type.  For example, if type is vec4,
+ * this creates a constant value of 1.0 having type float.
+ *
+ * If the given type is invalid for increment and decrement operators, return
+ * a floating point 1--the error will be detected later.
+ */
+static ir_rvalue *
+constant_one_for_inc_dec(void *ctx, const glsl_type *type)
+{
+   switch (type->base_type) {
+   case GLSL_TYPE_UINT:
+      return new(ctx) ir_constant((unsigned) 1);
+   case GLSL_TYPE_INT:
+      return new(ctx) ir_constant(1);
+   default:
+   case GLSL_TYPE_FLOAT:
+      return new(ctx) ir_constant(1.0f);
+   }
+}
+
+ir_rvalue *
+ast_expression::hir(exec_list *instructions,
+                    struct _mesa_glsl_parse_state *state)
+{
+   return do_hir(instructions, state, true);
+}
+
+void
+ast_expression::hir_no_rvalue(exec_list *instructions,
+                              struct _mesa_glsl_parse_state *state)
+{
+   do_hir(instructions, state, false);
+}
+
+ir_rvalue *
+ast_expression::do_hir(exec_list *instructions,
+                       struct _mesa_glsl_parse_state *state,
+                       bool needs_rvalue)
+{
+   void *ctx = state;
+   static const int operations[AST_NUM_OPERATORS] = {
+      -1,               /* ast_assign doesn't convert to ir_expression. */
+      -1,               /* ast_plus doesn't convert to ir_expression. */
+      ir_unop_neg,
+      ir_binop_add,
+      ir_binop_sub,
+      ir_binop_mul,
+      ir_binop_div,
+      ir_binop_mod,
+      ir_binop_lshift,
+      ir_binop_rshift,
+      ir_binop_less,
+      ir_binop_greater,
+      ir_binop_lequal,
+      ir_binop_gequal,
+      ir_binop_all_equal,
+      ir_binop_any_nequal,
+      ir_binop_bit_and,
+      ir_binop_bit_xor,
+      ir_binop_bit_or,
+      ir_unop_bit_not,
+      ir_binop_logic_and,
+      ir_binop_logic_xor,
+      ir_binop_logic_or,
+      ir_unop_logic_not,
+
+      /* Note: The following block of expression types actually convert
+       * to multiple IR instructions.
+       */
+      ir_binop_mul,     /* ast_mul_assign */
+      ir_binop_div,     /* ast_div_assign */
+      ir_binop_mod,     /* ast_mod_assign */
+      ir_binop_add,     /* ast_add_assign */
+      ir_binop_sub,     /* ast_sub_assign */
+      ir_binop_lshift,  /* ast_ls_assign */
+      ir_binop_rshift,  /* ast_rs_assign */
+      ir_binop_bit_and, /* ast_and_assign */
+      ir_binop_bit_xor, /* ast_xor_assign */
+      ir_binop_bit_or,  /* ast_or_assign */
+
+      -1,               /* ast_conditional doesn't convert to ir_expression. */
+      ir_binop_add,     /* ast_pre_inc. */
+      ir_binop_sub,     /* ast_pre_dec. */
+      ir_binop_add,     /* ast_post_inc. */
+      ir_binop_sub,     /* ast_post_dec. */
+      -1,               /* ast_field_selection doesn't conv to ir_expression. */
+      -1,               /* ast_array_index doesn't convert to ir_expression. */
+      -1,               /* ast_function_call doesn't conv to ir_expression. */
+      -1,               /* ast_identifier doesn't convert to ir_expression. */
+      -1,               /* ast_int_constant doesn't convert to ir_expression. */
+      -1,               /* ast_uint_constant doesn't conv to ir_expression. */
+      -1,               /* ast_float_constant doesn't conv to ir_expression. */
+      -1,               /* ast_bool_constant doesn't conv to ir_expression. */
+      -1,               /* ast_sequence doesn't convert to ir_expression. */
+   };
+   ir_rvalue *result = NULL;
+   ir_rvalue *op[3];
+   const struct glsl_type *type; /* a temporary variable for switch cases */
+   bool error_emitted = false;
+   YYLTYPE loc;
+
+   loc = this->get_location();
+
+   switch (this->oper) {
+   case ast_aggregate:
+      assert(!"ast_aggregate: Should never get here.");
+      break;
+
+   case ast_assign: {
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+
+      error_emitted =
+         do_assignment(instructions, state,
+                       this->subexpressions[0]->non_lvalue_description,
+                       op[0], op[1], &result, needs_rvalue, false,
+                       this->subexpressions[0]->get_location());
+      break;
+   }
+
+   case ast_plus:
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+
+      type = unary_arithmetic_result_type(op[0]->type, state, & loc);
+
+      error_emitted = type->is_error();
+
+      result = op[0];
+      break;
+
+   case ast_neg:
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+
+      type = unary_arithmetic_result_type(op[0]->type, state, & loc);
+
+      error_emitted = type->is_error();
+
+      result = new(ctx) ir_expression(operations[this->oper], type,
+                                      op[0], NULL);
+      break;
+
+   case ast_add:
+   case ast_sub:
+   case ast_mul:
+   case ast_div:
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+
+      type = arithmetic_result_type(op[0], op[1],
+                                    (this->oper == ast_mul),
+                                    state, & loc);
+      error_emitted = type->is_error();
+
+      result = new(ctx) ir_expression(operations[this->oper], type,
+                                      op[0], op[1]);
+      break;
+
+   case ast_mod:
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+
+      type = modulus_result_type(op[0], op[1], state, &loc);
+
+      assert(operations[this->oper] == ir_binop_mod);
+
+      result = new(ctx) ir_expression(operations[this->oper], type,
+                                      op[0], op[1]);
+      error_emitted = type->is_error();
+      break;
+
+   case ast_lshift:
+   case ast_rshift:
+       if (!state->check_bitwise_operations_allowed(&loc)) {
+          error_emitted = true;
+       }
+
+       op[0] = this->subexpressions[0]->hir(instructions, state);
+       op[1] = this->subexpressions[1]->hir(instructions, state);
+       type = shift_result_type(op[0]->type, op[1]->type, this->oper, state,
+                                &loc);
+       result = new(ctx) ir_expression(operations[this->oper], type,
+                                       op[0], op[1]);
+       error_emitted = op[0]->type->is_error() || op[1]->type->is_error();
+       break;
+
+   case ast_less:
+   case ast_greater:
+   case ast_lequal:
+   case ast_gequal:
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+
+      type = relational_result_type(op[0], op[1], state, & loc);
+
+      /* The relational operators must either generate an error or result
+       * in a scalar boolean.  See page 57 of the GLSL 1.50 spec.
+       */
+      assert(type->is_error()
+	     || ((type->base_type == GLSL_TYPE_BOOL)
+		 && type->is_scalar()));
+
+      result = new(ctx) ir_expression(operations[this->oper], type,
+                                      op[0], op[1]);
+      error_emitted = type->is_error();
+      break;
+
+   case ast_nequal:
+   case ast_equal:
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+
+      /* From page 58 (page 64 of the PDF) of the GLSL 1.50 spec:
+       *
+       *    "The equality operators equal (==), and not equal (!=)
+       *    operate on all types. They result in a scalar Boolean. If
+       *    the operand types do not match, then there must be a
+       *    conversion from Section 4.1.10 "Implicit Conversions"
+       *    applied to one operand that can make them match, in which
+       *    case this conversion is done."
+       */
+
+      if (op[0]->type == glsl_type::void_type || op[1]->type == glsl_type::void_type) {
+         _mesa_glsl_error(& loc, state, "`%s':  wrong operand types: "
+                         "no operation `%1$s' exists that takes a left-hand "
+                         "operand of type 'void' or a right operand of type "
+                         "'void'", (this->oper == ast_equal) ? "==" : "!=");
+         error_emitted = true;
+      } else if ((!apply_implicit_conversion(op[0]->type, op[1], state)
+           && !apply_implicit_conversion(op[1]->type, op[0], state))
+          || (op[0]->type != op[1]->type)) {
+         _mesa_glsl_error(& loc, state, "operands of `%s' must have the same "
+                          "type", (this->oper == ast_equal) ? "==" : "!=");
+         error_emitted = true;
+      } else if ((op[0]->type->is_array() || op[1]->type->is_array()) &&
+                 !state->check_version(120, 300, &loc,
+                                       "array comparisons forbidden")) {
+         error_emitted = true;
+      } else if ((op[0]->type->contains_opaque() ||
+                  op[1]->type->contains_opaque())) {
+         _mesa_glsl_error(&loc, state, "opaque type comparisons forbidden");
+         error_emitted = true;
+      }
+
+      if (error_emitted) {
+         result = new(ctx) ir_constant(false);
+      } else {
+         result = do_comparison(ctx, operations[this->oper], op[0], op[1]);
+         assert(result->type == glsl_type::bool_type);
+      }
+      break;
+
+   case ast_bit_and:
+   case ast_bit_xor:
+   case ast_bit_or:
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+      type = bit_logic_result_type(op[0], op[1], this->oper, state, &loc);
+      result = new(ctx) ir_expression(operations[this->oper], type,
+                                      op[0], op[1]);
+      error_emitted = op[0]->type->is_error() || op[1]->type->is_error();
+      break;
+
+   case ast_bit_not:
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+
+      if (!state->check_bitwise_operations_allowed(&loc)) {
+         error_emitted = true;
+      }
+
+      if (!op[0]->type->is_integer()) {
+         _mesa_glsl_error(&loc, state, "operand of `~' must be an integer");
+         error_emitted = true;
+      }
+
+      type = error_emitted ? glsl_type::error_type : op[0]->type;
+      result = new(ctx) ir_expression(ir_unop_bit_not, type, op[0], NULL);
+      break;
+
+   case ast_logic_and: {
+      exec_list rhs_instructions;
+      op[0] = get_scalar_boolean_operand(instructions, state, this, 0,
+                                         "LHS", &error_emitted);
+      op[1] = get_scalar_boolean_operand(&rhs_instructions, state, this, 1,
+                                         "RHS", &error_emitted);
+
+      if (rhs_instructions.is_empty()) {
+         result = new(ctx) ir_expression(ir_binop_logic_and, op[0], op[1]);
+         type = result->type;
+      } else {
+         ir_variable *const tmp = new(ctx) ir_variable(glsl_type::bool_type,
+                                                       "and_tmp",
+                                                       ir_var_temporary);
+         instructions->push_tail(tmp);
+
+         ir_if *const stmt = new(ctx) ir_if(op[0]);
+         instructions->push_tail(stmt);
+
+         stmt->then_instructions.append_list(&rhs_instructions);
+         ir_dereference *const then_deref = new(ctx) ir_dereference_variable(tmp);
+         ir_assignment *const then_assign =
+            new(ctx) ir_assignment(then_deref, op[1]);
+         stmt->then_instructions.push_tail(then_assign);
+
+         ir_dereference *const else_deref = new(ctx) ir_dereference_variable(tmp);
+         ir_assignment *const else_assign =
+            new(ctx) ir_assignment(else_deref, new(ctx) ir_constant(false));
+         stmt->else_instructions.push_tail(else_assign);
+
+         result = new(ctx) ir_dereference_variable(tmp);
+         type = tmp->type;
+      }
+      break;
+   }
+
+   case ast_logic_or: {
+      exec_list rhs_instructions;
+      op[0] = get_scalar_boolean_operand(instructions, state, this, 0,
+                                         "LHS", &error_emitted);
+      op[1] = get_scalar_boolean_operand(&rhs_instructions, state, this, 1,
+                                         "RHS", &error_emitted);
+
+      if (rhs_instructions.is_empty()) {
+         result = new(ctx) ir_expression(ir_binop_logic_or, op[0], op[1]);
+         type = result->type;
+      } else {
+         ir_variable *const tmp = new(ctx) ir_variable(glsl_type::bool_type,
+                                                       "or_tmp",
+                                                       ir_var_temporary);
+         instructions->push_tail(tmp);
+
+         ir_if *const stmt = new(ctx) ir_if(op[0]);
+         instructions->push_tail(stmt);
+
+         ir_dereference *const then_deref = new(ctx) ir_dereference_variable(tmp);
+         ir_assignment *const then_assign =
+            new(ctx) ir_assignment(then_deref, new(ctx) ir_constant(true));
+         stmt->then_instructions.push_tail(then_assign);
+
+         stmt->else_instructions.append_list(&rhs_instructions);
+         ir_dereference *const else_deref = new(ctx) ir_dereference_variable(tmp);
+         ir_assignment *const else_assign =
+            new(ctx) ir_assignment(else_deref, op[1]);
+         stmt->else_instructions.push_tail(else_assign);
+
+         result = new(ctx) ir_dereference_variable(tmp);
+         type = tmp->type;
+      }
+      break;
+   }
+
+   case ast_logic_xor:
+      /* From page 33 (page 39 of the PDF) of the GLSL 1.10 spec:
+       *
+       *    "The logical binary operators and (&&), or ( | | ), and
+       *     exclusive or (^^). They operate only on two Boolean
+       *     expressions and result in a Boolean expression."
+       */
+      op[0] = get_scalar_boolean_operand(instructions, state, this, 0, "LHS",
+                                         &error_emitted);
+      op[1] = get_scalar_boolean_operand(instructions, state, this, 1, "RHS",
+                                         &error_emitted);
+
+      result = new(ctx) ir_expression(operations[this->oper], glsl_type::bool_type,
+                                      op[0], op[1]);
+      break;
+
+   case ast_logic_not:
+      op[0] = get_scalar_boolean_operand(instructions, state, this, 0,
+                                         "operand", &error_emitted);
+
+      result = new(ctx) ir_expression(operations[this->oper], glsl_type::bool_type,
+                                      op[0], NULL);
+      break;
+
+   case ast_mul_assign:
+   case ast_div_assign:
+   case ast_add_assign:
+   case ast_sub_assign: {
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+
+      type = arithmetic_result_type(op[0], op[1],
+                                    (this->oper == ast_mul_assign),
+                                    state, & loc);
+
+      ir_rvalue *temp_rhs = new(ctx) ir_expression(operations[this->oper], type,
+                                                   op[0], op[1]);
+
+      error_emitted =
+         do_assignment(instructions, state,
+                       this->subexpressions[0]->non_lvalue_description,
+                       op[0]->clone(ctx, NULL), temp_rhs,
+                       &result, needs_rvalue, false,
+                       this->subexpressions[0]->get_location());
+
+      /* GLSL 1.10 does not allow array assignment.  However, we don't have to
+       * explicitly test for this because none of the binary expression
+       * operators allow array operands either.
+       */
+
+      break;
+   }
+
+   case ast_mod_assign: {
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+
+      type = modulus_result_type(op[0], op[1], state, &loc);
+
+      assert(operations[this->oper] == ir_binop_mod);
+
+      ir_rvalue *temp_rhs;
+      temp_rhs = new(ctx) ir_expression(operations[this->oper], type,
+                                        op[0], op[1]);
+
+      error_emitted =
+         do_assignment(instructions, state,
+                       this->subexpressions[0]->non_lvalue_description,
+                       op[0]->clone(ctx, NULL), temp_rhs,
+                       &result, needs_rvalue, false,
+                       this->subexpressions[0]->get_location());
+      break;
+   }
+
+   case ast_ls_assign:
+   case ast_rs_assign: {
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+      type = shift_result_type(op[0]->type, op[1]->type, this->oper, state,
+                               &loc);
+      ir_rvalue *temp_rhs = new(ctx) ir_expression(operations[this->oper],
+                                                   type, op[0], op[1]);
+      error_emitted =
+         do_assignment(instructions, state,
+                       this->subexpressions[0]->non_lvalue_description,
+                       op[0]->clone(ctx, NULL), temp_rhs,
+                       &result, needs_rvalue, false,
+                       this->subexpressions[0]->get_location());
+      break;
+   }
+
+   case ast_and_assign:
+   case ast_xor_assign:
+   case ast_or_assign: {
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+      type = bit_logic_result_type(op[0], op[1], this->oper, state, &loc);
+      ir_rvalue *temp_rhs = new(ctx) ir_expression(operations[this->oper],
+                                                   type, op[0], op[1]);
+      error_emitted =
+         do_assignment(instructions, state,
+                       this->subexpressions[0]->non_lvalue_description,
+                       op[0]->clone(ctx, NULL), temp_rhs,
+                       &result, needs_rvalue, false,
+                       this->subexpressions[0]->get_location());
+      break;
+   }
+
+   case ast_conditional: {
+      /* From page 59 (page 65 of the PDF) of the GLSL 1.50 spec:
+       *
+       *    "The ternary selection operator (?:). It operates on three
+       *    expressions (exp1 ? exp2 : exp3). This operator evaluates the
+       *    first expression, which must result in a scalar Boolean."
+       */
+      op[0] = get_scalar_boolean_operand(instructions, state, this, 0,
+                                         "condition", &error_emitted);
+
+      /* The :? operator is implemented by generating an anonymous temporary
+       * followed by an if-statement.  The last instruction in each branch of
+       * the if-statement assigns a value to the anonymous temporary.  This
+       * temporary is the r-value of the expression.
+       */
+      exec_list then_instructions;
+      exec_list else_instructions;
+
+      op[1] = this->subexpressions[1]->hir(&then_instructions, state);
+      op[2] = this->subexpressions[2]->hir(&else_instructions, state);
+
+      /* From page 59 (page 65 of the PDF) of the GLSL 1.50 spec:
+       *
+       *     "The second and third expressions can be any type, as
+       *     long their types match, or there is a conversion in
+       *     Section 4.1.10 "Implicit Conversions" that can be applied
+       *     to one of the expressions to make their types match. This
+       *     resulting matching type is the type of the entire
+       *     expression."
+       */
+      if ((!apply_implicit_conversion(op[1]->type, op[2], state)
+          && !apply_implicit_conversion(op[2]->type, op[1], state))
+          || (op[1]->type != op[2]->type)) {
+         YYLTYPE loc = this->subexpressions[1]->get_location();
+
+         _mesa_glsl_error(& loc, state, "second and third operands of ?: "
+                          "operator must have matching types");
+         error_emitted = true;
+         type = glsl_type::error_type;
+      } else {
+         type = op[1]->type;
+      }
+
+      /* From page 33 (page 39 of the PDF) of the GLSL 1.10 spec:
+       *
+       *    "The second and third expressions must be the same type, but can
+       *    be of any type other than an array."
+       */
+      if (type->is_array() &&
+          !state->check_version(120, 300, &loc,
+                                "second and third operands of ?: operator "
+                                "cannot be arrays")) {
+         error_emitted = true;
+      }
+
+      /* From section 4.1.7 of the GLSL 4.50 spec (Opaque Types):
+       *
+       *  "Except for array indexing, structure member selection, and
+       *   parentheses, opaque variables are not allowed to be operands in
+       *   expressions; such use results in a compile-time error."
+       */
+      if (type->contains_opaque()) {
+         _mesa_glsl_error(&loc, state, "opaque variables cannot be operands "
+                          "of the ?: operator");
+         error_emitted = true;
+      }
+
+      ir_constant *cond_val = op[0]->constant_expression_value();
+
+      if (then_instructions.is_empty()
+          && else_instructions.is_empty()
+          && cond_val != NULL) {
+         result = cond_val->value.b[0] ? op[1] : op[2];
+      } else {
+         /* The copy to conditional_tmp reads the whole array. */
+         if (type->is_array()) {
+            mark_whole_array_access(op[1]);
+            mark_whole_array_access(op[2]);
+         }
+
+         ir_variable *const tmp =
+            new(ctx) ir_variable(type, "conditional_tmp", ir_var_temporary);
+         instructions->push_tail(tmp);
+
+         ir_if *const stmt = new(ctx) ir_if(op[0]);
+         instructions->push_tail(stmt);
+
+         then_instructions.move_nodes_to(& stmt->then_instructions);
+         ir_dereference *const then_deref =
+            new(ctx) ir_dereference_variable(tmp);
+         ir_assignment *const then_assign =
+            new(ctx) ir_assignment(then_deref, op[1]);
+         stmt->then_instructions.push_tail(then_assign);
+
+         else_instructions.move_nodes_to(& stmt->else_instructions);
+         ir_dereference *const else_deref =
+            new(ctx) ir_dereference_variable(tmp);
+         ir_assignment *const else_assign =
+            new(ctx) ir_assignment(else_deref, op[2]);
+         stmt->else_instructions.push_tail(else_assign);
+
+         result = new(ctx) ir_dereference_variable(tmp);
+      }
+      break;
+   }
+
+   case ast_pre_inc:
+   case ast_pre_dec: {
+      this->non_lvalue_description = (this->oper == ast_pre_inc)
+         ? "pre-increment operation" : "pre-decrement operation";
+
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = constant_one_for_inc_dec(ctx, op[0]->type);
+
+      type = arithmetic_result_type(op[0], op[1], false, state, & loc);
+
+      ir_rvalue *temp_rhs;
+      temp_rhs = new(ctx) ir_expression(operations[this->oper], type,
+                                        op[0], op[1]);
+
+      error_emitted =
+         do_assignment(instructions, state,
+                       this->subexpressions[0]->non_lvalue_description,
+                       op[0]->clone(ctx, NULL), temp_rhs,
+                       &result, needs_rvalue, false,
+                       this->subexpressions[0]->get_location());
+      break;
+   }
+
+   case ast_post_inc:
+   case ast_post_dec: {
+      this->non_lvalue_description = (this->oper == ast_post_inc)
+         ? "post-increment operation" : "post-decrement operation";
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = constant_one_for_inc_dec(ctx, op[0]->type);
+
+      error_emitted = op[0]->type->is_error() || op[1]->type->is_error();
+
+      type = arithmetic_result_type(op[0], op[1], false, state, & loc);
+
+      ir_rvalue *temp_rhs;
+      temp_rhs = new(ctx) ir_expression(operations[this->oper], type,
+                                        op[0], op[1]);
+
+      /* Get a temporary of a copy of the lvalue before it's modified.
+       * This may get thrown away later.
+       */
+      result = get_lvalue_copy(instructions, op[0]->clone(ctx, NULL));
+
+      ir_rvalue *junk_rvalue;
+      error_emitted =
+         do_assignment(instructions, state,
+                       this->subexpressions[0]->non_lvalue_description,
+                       op[0]->clone(ctx, NULL), temp_rhs,
+                       &junk_rvalue, false, false,
+                       this->subexpressions[0]->get_location());
+
+      break;
+   }
+
+   case ast_field_selection:
+      result = _mesa_ast_field_selection_to_hir(this, instructions, state);
+      break;
+
+   case ast_array_index: {
+      YYLTYPE index_loc = subexpressions[1]->get_location();
+
+      op[0] = subexpressions[0]->hir(instructions, state);
+      op[1] = subexpressions[1]->hir(instructions, state);
+
+      result = _mesa_ast_array_index_to_hir(ctx, state, op[0], op[1],
+                                            loc, index_loc);
+
+      if (result->type->is_error())
+         error_emitted = true;
+
+      break;
+   }
+
+   case ast_unsized_array_dim:
+      assert(!"ast_unsized_array_dim: Should never get here.");
+      break;
+
+   case ast_function_call:
+      /* Should *NEVER* get here.  ast_function_call should always be handled
+       * by ast_function_expression::hir.
+       */
+      assert(0);
+      break;
+
+   case ast_identifier: {
+      /* ast_identifier can appear several places in a full abstract syntax
+       * tree.  This particular use must be at location specified in the grammar
+       * as 'variable_identifier'.
+       */
+      ir_variable *var =
+         state->symbols->get_variable(this->primary_expression.identifier);
+
+      if (var != NULL) {
+         var->data.used = true;
+         result = new(ctx) ir_dereference_variable(var);
+      } else {
+         _mesa_glsl_error(& loc, state, "`%s' undeclared",
+                          this->primary_expression.identifier);
+
+         result = ir_rvalue::error_value(ctx);
+         error_emitted = true;
+      }
+      break;
+   }
+
+   case ast_int_constant:
+      result = new(ctx) ir_constant(this->primary_expression.int_constant);
+      break;
+
+   case ast_uint_constant:
+      result = new(ctx) ir_constant(this->primary_expression.uint_constant);
+      break;
+
+   case ast_float_constant:
+      result = new(ctx) ir_constant(this->primary_expression.float_constant);
+      break;
+
+   case ast_bool_constant:
+      result = new(ctx) ir_constant(bool(this->primary_expression.bool_constant));
+      break;
+
+   case ast_double_constant:
+      result = new(ctx) ir_constant(this->primary_expression.double_constant);
+      break;
+
+   case ast_sequence: {
+      /* It should not be possible to generate a sequence in the AST without
+       * any expressions in it.
+       */
+      assert(!this->expressions.is_empty());
+
+      /* The r-value of a sequence is the last expression in the sequence.  If
+       * the other expressions in the sequence do not have side-effects (and
+       * therefore add instructions to the instruction list), they get dropped
+       * on the floor.
+       */
+      exec_node *previous_tail_pred = NULL;
+      YYLTYPE previous_operand_loc = loc;
+
+      foreach_list_typed (ast_node, ast, link, &this->expressions) {
+         /* If one of the operands of comma operator does not generate any
+          * code, we want to emit a warning.  At each pass through the loop
+          * previous_tail_pred will point to the last instruction in the
+          * stream *before* processing the previous operand.  Naturally,
+          * instructions->tail_pred will point to the last instruction in the
+          * stream *after* processing the previous operand.  If the two
+          * pointers match, then the previous operand had no effect.
+          *
+          * The warning behavior here differs slightly from GCC.  GCC will
+          * only emit a warning if none of the left-hand operands have an
+          * effect.  However, it will emit a warning for each.  I believe that
+          * there are some cases in C (especially with GCC extensions) where
+          * it is useful to have an intermediate step in a sequence have no
+          * effect, but I don't think these cases exist in GLSL.  Either way,
+          * it would be a giant hassle to replicate that behavior.
+          */
+         if (previous_tail_pred == instructions->tail_pred) {
+            _mesa_glsl_warning(&previous_operand_loc, state,
+                               "left-hand operand of comma expression has "
+                               "no effect");
+         }
+
+         /* tail_pred is directly accessed instead of using the get_tail()
+          * method for performance reasons.  get_tail() has extra code to
+          * return NULL when the list is empty.  We don't care about that
+          * here, so using tail_pred directly is fine.
+          */
+         previous_tail_pred = instructions->tail_pred;
+         previous_operand_loc = ast->get_location();
+
+         result = ast->hir(instructions, state);
+      }
+
+      /* Any errors should have already been emitted in the loop above.
+       */
+      error_emitted = true;
+      break;
+   }
+   }
+   type = NULL; /* use result->type, not type. */
+   assert(result != NULL || !needs_rvalue);
+
+   if (result && result->type->is_error() && !error_emitted)
+      _mesa_glsl_error(& loc, state, "type mismatch");
+
+   return result;
+}
+
+bool
+ast_expression::has_sequence_subexpression() const
+{
+   switch (this->oper) {
+   case ast_plus:
+   case ast_neg:
+   case ast_bit_not:
+   case ast_logic_not:
+   case ast_pre_inc:
+   case ast_pre_dec:
+   case ast_post_inc:
+   case ast_post_dec:
+      return this->subexpressions[0]->has_sequence_subexpression();
+
+   case ast_assign:
+   case ast_add:
+   case ast_sub:
+   case ast_mul:
+   case ast_div:
+   case ast_mod:
+   case ast_lshift:
+   case ast_rshift:
+   case ast_less:
+   case ast_greater:
+   case ast_lequal:
+   case ast_gequal:
+   case ast_nequal:
+   case ast_equal:
+   case ast_bit_and:
+   case ast_bit_xor:
+   case ast_bit_or:
+   case ast_logic_and:
+   case ast_logic_or:
+   case ast_logic_xor:
+   case ast_array_index:
+   case ast_mul_assign:
+   case ast_div_assign:
+   case ast_add_assign:
+   case ast_sub_assign:
+   case ast_mod_assign:
+   case ast_ls_assign:
+   case ast_rs_assign:
+   case ast_and_assign:
+   case ast_xor_assign:
+   case ast_or_assign:
+      return this->subexpressions[0]->has_sequence_subexpression() ||
+             this->subexpressions[1]->has_sequence_subexpression();
+
+   case ast_conditional:
+      return this->subexpressions[0]->has_sequence_subexpression() ||
+             this->subexpressions[1]->has_sequence_subexpression() ||
+             this->subexpressions[2]->has_sequence_subexpression();
+
+   case ast_sequence:
+      return true;
+
+   case ast_field_selection:
+   case ast_identifier:
+   case ast_int_constant:
+   case ast_uint_constant:
+   case ast_float_constant:
+   case ast_bool_constant:
+   case ast_double_constant:
+      return false;
+
+   case ast_aggregate:
+      unreachable("ast_aggregate: Should never get here.");
+
+   case ast_function_call:
+      unreachable("should be handled by ast_function_expression::hir");
+
+   case ast_unsized_array_dim:
+      unreachable("ast_unsized_array_dim: Should never get here.");
+   }
+
+   return false;
+}
+
+ir_rvalue *
+ast_expression_statement::hir(exec_list *instructions,
+                              struct _mesa_glsl_parse_state *state)
+{
+   /* It is possible to have expression statements that don't have an
+    * expression.  This is the solitary semicolon:
+    *
+    * for (i = 0; i < 5; i++)
+    *     ;
+    *
+    * In this case the expression will be NULL.  Test for NULL and don't do
+    * anything in that case.
+    */
+   if (expression != NULL)
+      expression->hir_no_rvalue(instructions, state);
+
+   /* Statements do not have r-values.
+    */
+   return NULL;
+}
+
+
+ir_rvalue *
+ast_compound_statement::hir(exec_list *instructions,
+                            struct _mesa_glsl_parse_state *state)
+{
+   if (new_scope)
+      state->symbols->push_scope();
+
+   foreach_list_typed (ast_node, ast, link, &this->statements)
+      ast->hir(instructions, state);
+
+   if (new_scope)
+      state->symbols->pop_scope();
+
+   /* Compound statements do not have r-values.
+    */
+   return NULL;
+}
+
+/**
+ * Evaluate the given exec_node (which should be an ast_node representing
+ * a single array dimension) and return its integer value.
+ */
+static unsigned
+process_array_size(exec_node *node,
+                   struct _mesa_glsl_parse_state *state)
+{
+   exec_list dummy_instructions;
+
+   ast_node *array_size = exec_node_data(ast_node, node, link);
+
+   /**
+    * Dimensions other than the outermost dimension can by unsized if they
+    * are immediately sized by a constructor or initializer.
+    */
+   if (((ast_expression*)array_size)->oper == ast_unsized_array_dim)
+      return 0;
+
+   ir_rvalue *const ir = array_size->hir(& dummy_instructions, state);
+   YYLTYPE loc = array_size->get_location();
+
+   if (ir == NULL) {
+      _mesa_glsl_error(& loc, state,
+                       "array size could not be resolved");
+      return 0;
+   }
+
+   if (!ir->type->is_integer()) {
+      _mesa_glsl_error(& loc, state,
+                       "array size must be integer type");
+      return 0;
+   }
+
+   if (!ir->type->is_scalar()) {
+      _mesa_glsl_error(& loc, state,
+                       "array size must be scalar type");
+      return 0;
+   }
+
+   ir_constant *const size = ir->constant_expression_value();
+   if (size == NULL || array_size->has_sequence_subexpression()) {
+      _mesa_glsl_error(& loc, state, "array size must be a "
+                       "constant valued expression");
+      return 0;
+   }
+
+   if (size->value.i[0] <= 0) {
+      _mesa_glsl_error(& loc, state, "array size must be > 0");
+      return 0;
+   }
+
+   assert(size->type == ir->type);
+
+   /* If the array size is const (and we've verified that
+    * it is) then no instructions should have been emitted
+    * when we converted it to HIR. If they were emitted,
+    * then either the array size isn't const after all, or
+    * we are emitting unnecessary instructions.
+    */
+   assert(dummy_instructions.is_empty());
+
+   return size->value.u[0];
+}
+
+static const glsl_type *
+process_array_type(YYLTYPE *loc, const glsl_type *base,
+                   ast_array_specifier *array_specifier,
+                   struct _mesa_glsl_parse_state *state)
+{
+   const glsl_type *array_type = base;
+
+   if (array_specifier != NULL) {
+      if (base->is_array()) {
+
+         /* From page 19 (page 25) of the GLSL 1.20 spec:
+          *
+          * "Only one-dimensional arrays may be declared."
+          */
+         if (!state->check_arrays_of_arrays_allowed(loc)) {
+            return glsl_type::error_type;
+         }
+      }
+
+      for (exec_node *node = array_specifier->array_dimensions.tail_pred;
+           !node->is_head_sentinel(); node = node->prev) {
+         unsigned array_size = process_array_size(node, state);
+         array_type = glsl_type::get_array_instance(array_type, array_size);
+      }
+   }
+
+   return array_type;
+}
+
+static bool
+precision_qualifier_allowed(const glsl_type *type)
+{
+   /* Precision qualifiers apply to floating point, integer and opaque
+    * types.
+    *
+    * Section 4.5.2 (Precision Qualifiers) of the GLSL 1.30 spec says:
+    *    "Any floating point or any integer declaration can have the type
+    *    preceded by one of these precision qualifiers [...] Literal
+    *    constants do not have precision qualifiers. Neither do Boolean
+    *    variables.
+    *
+    * Section 4.5 (Precision and Precision Qualifiers) of the GLSL 1.30
+    * spec also says:
+    *
+    *     "Precision qualifiers are added for code portability with OpenGL
+    *     ES, not for functionality. They have the same syntax as in OpenGL
+    *     ES."
+    *
+    * Section 8 (Built-In Functions) of the GLSL ES 1.00 spec says:
+    *
+    *     "uniform lowp sampler2D sampler;
+    *     highp vec2 coord;
+    *     ...
+    *     lowp vec4 col = texture2D (sampler, coord);
+    *                                            // texture2D returns lowp"
+    *
+    * From this, we infer that GLSL 1.30 (and later) should allow precision
+    * qualifiers on sampler types just like float and integer types.
+    */
+   return (type->is_float()
+       || type->is_integer()
+       || type->contains_opaque())
+       && !type->without_array()->is_record();
+}
+
+const glsl_type *
+ast_type_specifier::glsl_type(const char **name,
+                              struct _mesa_glsl_parse_state *state) const
+{
+   const struct glsl_type *type;
+
+   type = state->symbols->get_type(this->type_name);
+   *name = this->type_name;
+
+   YYLTYPE loc = this->get_location();
+   type = process_array_type(&loc, type, this->array_specifier, state);
+
+   return type;
+}
+
+/**
+ * From the OpenGL ES 3.0 spec, 4.5.4 Default Precision Qualifiers:
+ *
+ * "The precision statement
+ *
+ *    precision precision-qualifier type;
+ *
+ *  can be used to establish a default precision qualifier. The type field can
+ *  be either int or float or any of the sampler types, (...) If type is float,
+ *  the directive applies to non-precision-qualified floating point type
+ *  (scalar, vector, and matrix) declarations. If type is int, the directive
+ *  applies to all non-precision-qualified integer type (scalar, vector, signed,
+ *  and unsigned) declarations."
+ *
+ * We use the symbol table to keep the values of the default precisions for
+ * each 'type' in each scope and we use the 'type' string from the precision
+ * statement as key in the symbol table. When we want to retrieve the default
+ * precision associated with a given glsl_type we need to know the type string
+ * associated with it. This is what this function returns.
+ */
+static const char *
+get_type_name_for_precision_qualifier(const glsl_type *type)
+{
+   switch (type->base_type) {
+   case GLSL_TYPE_FLOAT:
+      return "float";
+   case GLSL_TYPE_UINT:
+   case GLSL_TYPE_INT:
+      return "int";
+   case GLSL_TYPE_ATOMIC_UINT:
+      return "atomic_uint";
+   case GLSL_TYPE_IMAGE:
+   /* fallthrough */
+   case GLSL_TYPE_SAMPLER: {
+      const unsigned type_idx =
+         type->sampler_array + 2 * type->sampler_shadow;
+      const unsigned offset = type->base_type == GLSL_TYPE_SAMPLER ? 0 : 4;
+      assert(type_idx < 4);
+      switch (type->sampler_type) {
+      case GLSL_TYPE_FLOAT:
+         switch (type->sampler_dimensionality) {
+         case GLSL_SAMPLER_DIM_1D: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "sampler1D", "sampler1DArray",
+              "sampler1DShadow", "sampler1DArrayShadow"
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_2D: {
+            static const char *const names[8] = {
+              "sampler2D", "sampler2DArray",
+              "sampler2DShadow", "sampler2DArrayShadow",
+              "image2D", "image2DArray", NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_3D: {
+            static const char *const names[8] = {
+              "sampler3D", NULL, NULL, NULL,
+              "image3D", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_CUBE: {
+            static const char *const names[8] = {
+              "samplerCube", "samplerCubeArray",
+              "samplerCubeShadow", "samplerCubeArrayShadow",
+              "imageCube", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_MS: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "sampler2DMS", "sampler2DMSArray", NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_RECT: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "samplerRect", NULL, "samplerRectShadow", NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_BUF: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "samplerBuffer", NULL, NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_EXTERNAL: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "samplerExternalOES", NULL, NULL, NULL
+            };
+            return names[type_idx];
+         }
+         default:
+            unreachable("Unsupported sampler/image dimensionality");
+         } /* sampler/image float dimensionality */
+         break;
+      case GLSL_TYPE_INT:
+         switch (type->sampler_dimensionality) {
+         case GLSL_SAMPLER_DIM_1D: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "isampler1D", "isampler1DArray", NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_2D: {
+            static const char *const names[8] = {
+              "isampler2D", "isampler2DArray", NULL, NULL,
+              "iimage2D", "iimage2DArray", NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_3D: {
+            static const char *const names[8] = {
+              "isampler3D", NULL, NULL, NULL,
+              "iimage3D", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_CUBE: {
+            static const char *const names[8] = {
+              "isamplerCube", "isamplerCubeArray", NULL, NULL,
+              "iimageCube", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_MS: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "isampler2DMS", "isampler2DMSArray", NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_RECT: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "isamplerRect", NULL, "isamplerRectShadow", NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_BUF: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "isamplerBuffer", NULL, NULL, NULL
+            };
+            return names[type_idx];
+         }
+         default:
+            unreachable("Unsupported isampler/iimage dimensionality");
+         } /* sampler/image int dimensionality */
+         break;
+      case GLSL_TYPE_UINT:
+         switch (type->sampler_dimensionality) {
+         case GLSL_SAMPLER_DIM_1D: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "usampler1D", "usampler1DArray", NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_2D: {
+            static const char *const names[8] = {
+              "usampler2D", "usampler2DArray", NULL, NULL,
+              "uimage2D", "uimage2DArray", NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_3D: {
+            static const char *const names[8] = {
+              "usampler3D", NULL, NULL, NULL,
+              "uimage3D", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_CUBE: {
+            static const char *const names[8] = {
+              "usamplerCube", "usamplerCubeArray", NULL, NULL,
+              "uimageCube", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_MS: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "usampler2DMS", "usampler2DMSArray", NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_RECT: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "usamplerRect", NULL, "usamplerRectShadow", NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_BUF: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "usamplerBuffer", NULL, NULL, NULL
+            };
+            return names[type_idx];
+         }
+         default:
+            unreachable("Unsupported usampler/uimage dimensionality");
+         } /* sampler/image uint dimensionality */
+         break;
+      default:
+         unreachable("Unsupported sampler/image type");
+      } /* sampler/image type */
+      break;
+   } /* GLSL_TYPE_SAMPLER/GLSL_TYPE_IMAGE */
+   break;
+   default:
+      unreachable("Unsupported type");
+   } /* base type */
+}
+
+static unsigned
+select_gles_precision(unsigned qual_precision,
+                      const glsl_type *type,
+                      struct _mesa_glsl_parse_state *state, YYLTYPE *loc)
+{
+   /* Precision qualifiers do not have any meaning in Desktop GLSL.
+    * In GLES we take the precision from the type qualifier if present,
+    * otherwise, if the type of the variable allows precision qualifiers at
+    * all, we look for the default precision qualifier for that type in the
+    * current scope.
+    */
+   assert(state->es_shader);
+
+   unsigned precision = GLSL_PRECISION_NONE;
+   if (qual_precision) {
+      precision = qual_precision;
+   } else if (precision_qualifier_allowed(type)) {
+      const char *type_name =
+         get_type_name_for_precision_qualifier(type->without_array());
+      assert(type_name != NULL);
+
+      precision =
+         state->symbols->get_default_precision_qualifier(type_name);
+      if (precision == ast_precision_none) {
+         _mesa_glsl_error(loc, state,
+                          "No precision specified in this scope for type `%s'",
+                          type->name);
+      }
+   }
+   return precision;
+}
+
+const glsl_type *
+ast_fully_specified_type::glsl_type(const char **name,
+                                    struct _mesa_glsl_parse_state *state) const
+{
+   return this->specifier->glsl_type(name, state);
+}
+
+/**
+ * Determine whether a toplevel variable declaration declares a varying.  This
+ * function operates by examining the variable's mode and the shader target,
+ * so it correctly identifies linkage variables regardless of whether they are
+ * declared using the deprecated "varying" syntax or the new "in/out" syntax.
+ *
+ * Passing a non-toplevel variable declaration (e.g. a function parameter) to
+ * this function will produce undefined results.
+ */
+static bool
+is_varying_var(ir_variable *var, gl_shader_stage target)
+{
+   switch (target) {
+   case MESA_SHADER_VERTEX:
+      return var->data.mode == ir_var_shader_out;
+   case MESA_SHADER_FRAGMENT:
+      return var->data.mode == ir_var_shader_in;
+   default:
+      return var->data.mode == ir_var_shader_out || var->data.mode == ir_var_shader_in;
+   }
+}
+
+
+/**
+ * Matrix layout qualifiers are only allowed on certain types
+ */
+static void
+validate_matrix_layout_for_type(struct _mesa_glsl_parse_state *state,
+                                YYLTYPE *loc,
+                                const glsl_type *type,
+                                ir_variable *var)
+{
+   if (var && !var->is_in_buffer_block()) {
+      /* Layout qualifiers may only apply to interface blocks and fields in
+       * them.
+       */
+      _mesa_glsl_error(loc, state,
+                       "uniform block layout qualifiers row_major and "
+                       "column_major may not be applied to variables "
+                       "outside of uniform blocks");
+   } else if (!type->without_array()->is_matrix()) {
+      /* The OpenGL ES 3.0 conformance tests did not originally allow
+       * matrix layout qualifiers on non-matrices.  However, the OpenGL
+       * 4.4 and OpenGL ES 3.0 (revision TBD) specifications were
+       * amended to specifically allow these layouts on all types.  Emit
+       * a warning so that people know their code may not be portable.
+       */
+      _mesa_glsl_warning(loc, state,
+                         "uniform block layout qualifiers row_major and "
+                         "column_major applied to non-matrix types may "
+                         "be rejected by older compilers");
+   }
+}
+
+static bool
+process_qualifier_constant(struct _mesa_glsl_parse_state *state,
+                           YYLTYPE *loc,
+                           const char *qual_indentifier,
+                           ast_expression *const_expression,
+                           unsigned *value)
+{
+   exec_list dummy_instructions;
+
+   if (const_expression == NULL) {
+      *value = 0;
+      return true;
+   }
+
+   ir_rvalue *const ir = const_expression->hir(&dummy_instructions, state);
+
+   ir_constant *const const_int = ir->constant_expression_value();
+   if (const_int == NULL || !const_int->type->is_integer()) {
+      _mesa_glsl_error(loc, state, "%s must be an integral constant "
+                       "expression", qual_indentifier);
+      return false;
+   }
+
+   if (const_int->value.i[0] < 0) {
+      _mesa_glsl_error(loc, state, "%s layout qualifier is invalid (%d < 0)",
+                       qual_indentifier, const_int->value.u[0]);
+      return false;
+   }
+
+   /* If the location is const (and we've verified that
+    * it is) then no instructions should have been emitted
+    * when we converted it to HIR. If they were emitted,
+    * then either the location isn't const after all, or
+    * we are emitting unnecessary instructions.
+    */
+   assert(dummy_instructions.is_empty());
+
+   *value = const_int->value.u[0];
+   return true;
+}
+
+static bool
+validate_stream_qualifier(YYLTYPE *loc, struct _mesa_glsl_parse_state *state,
+                          unsigned stream)
+{
+   if (stream >= state->ctx->Const.MaxVertexStreams) {
+      _mesa_glsl_error(loc, state,
+                       "invalid stream specified %d is larger than "
+                       "MAX_VERTEX_STREAMS - 1 (%d).",
+                       stream, state->ctx->Const.MaxVertexStreams - 1);
+      return false;
+   }
+
+   return true;
+}
+
+static void
+apply_explicit_binding(struct _mesa_glsl_parse_state *state,
+                       YYLTYPE *loc,
+                       ir_variable *var,
+                       const glsl_type *type,
+                       const ast_type_qualifier *qual)
+{
+   if (!qual->flags.q.uniform && !qual->flags.q.buffer) {
+      _mesa_glsl_error(loc, state,
+                       "the \"binding\" qualifier only applies to uniforms and "
+                       "shader storage buffer objects");
+      return;
+   }
+
+   unsigned qual_binding;
+   if (!process_qualifier_constant(state, loc, "binding", qual->binding,
+                                   &qual_binding)) {
+      return;
+   }
+
+   const struct gl_context *const ctx = state->ctx;
+   unsigned elements = type->is_array() ? type->arrays_of_arrays_size() : 1;
+   unsigned max_index = qual_binding + elements - 1;
+   const glsl_type *base_type = type->without_array();
+
+   if (base_type->is_interface()) {
+      /* UBOs.  From page 60 of the GLSL 4.20 specification:
+       * "If the binding point for any uniform block instance is less than zero,
+       *  or greater than or equal to the implementation-dependent maximum
+       *  number of uniform buffer bindings, a compilation error will occur.
+       *  When the binding identifier is used with a uniform block instanced as
+       *  an array of size N, all elements of the array from binding through
+       *  binding + N – 1 must be within this range."
+       *
+       * The implementation-dependent maximum is GL_MAX_UNIFORM_BUFFER_BINDINGS.
+       */
+      if (qual->flags.q.uniform &&
+         max_index >= ctx->Const.MaxUniformBufferBindings) {
+         _mesa_glsl_error(loc, state, "layout(binding = %u) for %d UBOs exceeds "
+                          "the maximum number of UBO binding points (%d)",
+                          qual_binding, elements,
+                          ctx->Const.MaxUniformBufferBindings);
+         return;
+      }
+
+      /* SSBOs. From page 67 of the GLSL 4.30 specification:
+       * "If the binding point for any uniform or shader storage block instance
+       *  is less than zero, or greater than or equal to the
+       *  implementation-dependent maximum number of uniform buffer bindings, a
+       *  compile-time error will occur. When the binding identifier is used
+       *  with a uniform or shader storage block instanced as an array of size
+       *  N, all elements of the array from binding through binding + N – 1 must
+       *  be within this range."
+       */
+      if (qual->flags.q.buffer &&
+         max_index >= ctx->Const.MaxShaderStorageBufferBindings) {
+         _mesa_glsl_error(loc, state, "layout(binding = %u) for %d SSBOs exceeds "
+                          "the maximum number of SSBO binding points (%d)",
+                          qual_binding, elements,
+                          ctx->Const.MaxShaderStorageBufferBindings);
+         return;
+      }
+   } else if (base_type->is_sampler()) {
+      /* Samplers.  From page 63 of the GLSL 4.20 specification:
+       * "If the binding is less than zero, or greater than or equal to the
+       *  implementation-dependent maximum supported number of units, a
+       *  compilation error will occur. When the binding identifier is used
+       *  with an array of size N, all elements of the array from binding
+       *  through binding + N - 1 must be within this range."
+       */
+      unsigned limit = ctx->Const.MaxCombinedTextureImageUnits;
+
+      if (max_index >= limit) {
+         _mesa_glsl_error(loc, state, "layout(binding = %d) for %d samplers "
+                          "exceeds the maximum number of texture image units "
+                          "(%u)", qual_binding, elements, limit);
+
+         return;
+      }
+   } else if (base_type->contains_atomic()) {
+      assert(ctx->Const.MaxAtomicBufferBindings <= MAX_COMBINED_ATOMIC_BUFFERS);
+      if (qual_binding >= ctx->Const.MaxAtomicBufferBindings) {
+         _mesa_glsl_error(loc, state, "layout(binding = %d) exceeds the "
+                          " maximum number of atomic counter buffer bindings"
+                          "(%u)", qual_binding,
+                          ctx->Const.MaxAtomicBufferBindings);
+
+         return;
+      }
+   } else if ((state->is_version(420, 310) ||
+               state->ARB_shading_language_420pack_enable) &&
+              base_type->is_image()) {
+      assert(ctx->Const.MaxImageUnits <= MAX_IMAGE_UNITS);
+      if (max_index >= ctx->Const.MaxImageUnits) {
+         _mesa_glsl_error(loc, state, "Image binding %d exceeds the "
+                          " maximum number of image units (%d)", max_index,
+                          ctx->Const.MaxImageUnits);
+         return;
+      }
+
+   } else {
+      _mesa_glsl_error(loc, state,
+                       "the \"binding\" qualifier only applies to uniform "
+                       "blocks, opaque variables, or arrays thereof");
+      return;
+   }
+
+   var->data.explicit_binding = true;
+   var->data.binding = qual_binding;
+
+   return;
+}
+
+
+static glsl_interp_qualifier
+interpret_interpolation_qualifier(const struct ast_type_qualifier *qual,
+                                  ir_variable_mode mode,
+                                  struct _mesa_glsl_parse_state *state,
+                                  YYLTYPE *loc)
+{
+   glsl_interp_qualifier interpolation;
+   if (qual->flags.q.flat)
+      interpolation = INTERP_QUALIFIER_FLAT;
+   else if (qual->flags.q.noperspective)
+      interpolation = INTERP_QUALIFIER_NOPERSPECTIVE;
+   else if (qual->flags.q.smooth)
+      interpolation = INTERP_QUALIFIER_SMOOTH;
+   else
+      interpolation = INTERP_QUALIFIER_NONE;
+
+   if (interpolation != INTERP_QUALIFIER_NONE) {
+      if (mode != ir_var_shader_in && mode != ir_var_shader_out) {
+         _mesa_glsl_error(loc, state,
+                          "interpolation qualifier `%s' can only be applied to "
+                          "shader inputs or outputs.",
+                          interpolation_string(interpolation));
+
+      }
+
+      if ((state->stage == MESA_SHADER_VERTEX && mode == ir_var_shader_in) ||
+          (state->stage == MESA_SHADER_FRAGMENT && mode == ir_var_shader_out)) {
+         _mesa_glsl_error(loc, state,
+                          "interpolation qualifier `%s' cannot be applied to "
+                          "vertex shader inputs or fragment shader outputs",
+                          interpolation_string(interpolation));
+      }
+   }
+
+   return interpolation;
+}
+
+
+static void
+apply_explicit_location(const struct ast_type_qualifier *qual,
+                        ir_variable *var,
+                        struct _mesa_glsl_parse_state *state,
+                        YYLTYPE *loc)
+{
+   bool fail = false;
+
+   unsigned qual_location;
+   if (!process_qualifier_constant(state, loc, "location", qual->location,
+                                   &qual_location)) {
+      return;
+   }
+
+   /* Checks for GL_ARB_explicit_uniform_location. */
+   if (qual->flags.q.uniform) {
+      if (!state->check_explicit_uniform_location_allowed(loc, var))
+         return;
+
+      const struct gl_context *const ctx = state->ctx;
+      unsigned max_loc = qual_location + var->type->uniform_locations() - 1;
+
+      if (max_loc >= ctx->Const.MaxUserAssignableUniformLocations) {
+         _mesa_glsl_error(loc, state, "location(s) consumed by uniform %s "
+                          ">= MAX_UNIFORM_LOCATIONS (%u)", var->name,
+                          ctx->Const.MaxUserAssignableUniformLocations);
+         return;
+      }
+
+      var->data.explicit_location = true;
+      var->data.location = qual_location;
+      return;
+   }
+
+   /* Between GL_ARB_explicit_attrib_location an
+    * GL_ARB_separate_shader_objects, the inputs and outputs of any shader
+    * stage can be assigned explicit locations.  The checking here associates
+    * the correct extension with the correct stage's input / output:
+    *
+    *                     input            output
+    *                     -----            ------
+    * vertex              explicit_loc     sso
+    * tess control        sso              sso
+    * tess eval           sso              sso
+    * geometry            sso              sso
+    * fragment            sso              explicit_loc
+    */
+   switch (state->stage) {
+   case MESA_SHADER_VERTEX:
+      if (var->data.mode == ir_var_shader_in) {
+         if (!state->check_explicit_attrib_location_allowed(loc, var))
+            return;
+
+         break;
+      }
+
+      if (var->data.mode == ir_var_shader_out) {
+         if (!state->check_separate_shader_objects_allowed(loc, var))
+            return;
+
+         break;
+      }
+
+      fail = true;
+      break;
+
+   case MESA_SHADER_TESS_CTRL:
+   case MESA_SHADER_TESS_EVAL:
+   case MESA_SHADER_GEOMETRY:
+      if (var->data.mode == ir_var_shader_in || var->data.mode == ir_var_shader_out) {
+         if (!state->check_separate_shader_objects_allowed(loc, var))
+            return;
+
+         break;
+      }
+
+      fail = true;
+      break;
+
+   case MESA_SHADER_FRAGMENT:
+      if (var->data.mode == ir_var_shader_in) {
+         if (!state->check_separate_shader_objects_allowed(loc, var))
+            return;
+
+         break;
+      }
+
+      if (var->data.mode == ir_var_shader_out) {
+         if (!state->check_explicit_attrib_location_allowed(loc, var))
+            return;
+
+         break;
+      }
+
+      fail = true;
+      break;
+
+   case MESA_SHADER_COMPUTE:
+      _mesa_glsl_error(loc, state,
+                       "compute shader variables cannot be given "
+                       "explicit locations");
+      return;
+   };
+
+   if (fail) {
+      _mesa_glsl_error(loc, state,
+                       "%s cannot be given an explicit location in %s shader",
+                       mode_string(var),
+      _mesa_shader_stage_to_string(state->stage));
+   } else {
+      var->data.explicit_location = true;
+
+      switch (state->stage) {
+      case MESA_SHADER_VERTEX:
+         var->data.location = (var->data.mode == ir_var_shader_in)
+            ? (qual_location + VERT_ATTRIB_GENERIC0)
+            : (qual_location + VARYING_SLOT_VAR0);
+         break;
+
+      case MESA_SHADER_TESS_CTRL:
+      case MESA_SHADER_TESS_EVAL:
+      case MESA_SHADER_GEOMETRY:
+         if (var->data.patch)
+            var->data.location = qual_location + VARYING_SLOT_PATCH0;
+         else
+            var->data.location = qual_location + VARYING_SLOT_VAR0;
+         break;
+
+      case MESA_SHADER_FRAGMENT:
+         var->data.location = (var->data.mode == ir_var_shader_out)
+            ? (qual_location + FRAG_RESULT_DATA0)
+            : (qual_location + VARYING_SLOT_VAR0);
+         break;
+      case MESA_SHADER_COMPUTE:
+         assert(!"Unexpected shader type");
+         break;
+      }
+
+      /* Check if index was set for the uniform instead of the function */
+      if (qual->flags.q.explicit_index && qual->flags.q.subroutine) {
+         _mesa_glsl_error(loc, state, "an index qualifier can only be "
+                          "used with subroutine functions");
+         return;
+      }
+
+      unsigned qual_index;
+      if (qual->flags.q.explicit_index &&
+          process_qualifier_constant(state, loc, "index", qual->index,
+                                     &qual_index)) {
+         /* From the GLSL 4.30 specification, section 4.4.2 (Output
+          * Layout Qualifiers):
+          *
+          * "It is also a compile-time error if a fragment shader
+          *  sets a layout index to less than 0 or greater than 1."
+          *
+          * Older specifications don't mandate a behavior; we take
+          * this as a clarification and always generate the error.
+          */
+         if (qual_index > 1) {
+            _mesa_glsl_error(loc, state,
+                             "explicit index may only be 0 or 1");
+         } else {
+            var->data.explicit_index = true;
+            var->data.index = qual_index;
+         }
+      }
+   }
+}
+
+static void
+apply_image_qualifier_to_variable(const struct ast_type_qualifier *qual,
+                                  ir_variable *var,
+                                  struct _mesa_glsl_parse_state *state,
+                                  YYLTYPE *loc)
+{
+   const glsl_type *base_type = var->type->without_array();
+
+   if (base_type->is_image()) {
+      if (var->data.mode != ir_var_uniform &&
+          var->data.mode != ir_var_function_in) {
+         _mesa_glsl_error(loc, state, "image variables may only be declared as "
+                          "function parameters or uniform-qualified "
+                          "global variables");
+      }
+
+      var->data.image_read_only |= qual->flags.q.read_only;
+      var->data.image_write_only |= qual->flags.q.write_only;
+      var->data.image_coherent |= qual->flags.q.coherent;
+      var->data.image_volatile |= qual->flags.q._volatile;
+      var->data.image_restrict |= qual->flags.q.restrict_flag;
+      var->data.read_only = true;
+
+      if (qual->flags.q.explicit_image_format) {
+         if (var->data.mode == ir_var_function_in) {
+            _mesa_glsl_error(loc, state, "format qualifiers cannot be "
+                             "used on image function parameters");
+         }
+
+         if (qual->image_base_type != base_type->sampler_type) {
+            _mesa_glsl_error(loc, state, "format qualifier doesn't match the "
+                             "base data type of the image");
+         }
+
+         var->data.image_format = qual->image_format;
+      } else {
+         if (var->data.mode == ir_var_uniform) {
+            if (state->es_shader) {
+               _mesa_glsl_error(loc, state, "all image uniforms "
+                                "must have a format layout qualifier");
+
+            } else if (!qual->flags.q.write_only) {
+               _mesa_glsl_error(loc, state, "image uniforms not qualified with "
+                                "`writeonly' must have a format layout "
+                                "qualifier");
+            }
+         }
+
+         var->data.image_format = GL_NONE;
+      }
+
+      /* From page 70 of the GLSL ES 3.1 specification:
+       *
+       * "Except for image variables qualified with the format qualifiers
+       *  r32f, r32i, and r32ui, image variables must specify either memory
+       *  qualifier readonly or the memory qualifier writeonly."
+       */
+      if (state->es_shader &&
+          var->data.image_format != GL_R32F &&
+          var->data.image_format != GL_R32I &&
+          var->data.image_format != GL_R32UI &&
+          !var->data.image_read_only &&
+          !var->data.image_write_only) {
+         _mesa_glsl_error(loc, state, "image variables of format other than "
+                          "r32f, r32i or r32ui must be qualified `readonly' or "
+                          "`writeonly'");
+      }
+
+   } else if (qual->flags.q.read_only ||
+              qual->flags.q.write_only ||
+              qual->flags.q.coherent ||
+              qual->flags.q._volatile ||
+              qual->flags.q.restrict_flag ||
+              qual->flags.q.explicit_image_format) {
+      _mesa_glsl_error(loc, state, "memory qualifiers may only be applied to "
+                       "images");
+   }
+}
+
+static inline const char*
+get_layout_qualifier_string(bool origin_upper_left, bool pixel_center_integer)
+{
+   if (origin_upper_left && pixel_center_integer)
+      return "origin_upper_left, pixel_center_integer";
+   else if (origin_upper_left)
+      return "origin_upper_left";
+   else if (pixel_center_integer)
+      return "pixel_center_integer";
+   else
+      return " ";
+}
+
+static inline bool
+is_conflicting_fragcoord_redeclaration(struct _mesa_glsl_parse_state *state,
+                                       const struct ast_type_qualifier *qual)
+{
+   /* If gl_FragCoord was previously declared, and the qualifiers were
+    * different in any way, return true.
+    */
+   if (state->fs_redeclares_gl_fragcoord) {
+      return (state->fs_pixel_center_integer != qual->flags.q.pixel_center_integer
+         || state->fs_origin_upper_left != qual->flags.q.origin_upper_left);
+   }
+
+   return false;
+}
+
+static inline void
+validate_array_dimensions(const glsl_type *t,
+                          struct _mesa_glsl_parse_state *state,
+                          YYLTYPE *loc) {
+   if (t->is_array()) {
+      t = t->fields.array;
+      while (t->is_array()) {
+         if (t->is_unsized_array()) {
+            _mesa_glsl_error(loc, state,
+                             "only the outermost array dimension can "
+                             "be unsized",
+                             t->name);
+            break;
+         }
+         t = t->fields.array;
+      }
+   }
+}
+
+static void
+apply_layout_qualifier_to_variable(const struct ast_type_qualifier *qual,
+                                   ir_variable *var,
+                                   struct _mesa_glsl_parse_state *state,
+                                   YYLTYPE *loc)
+{
+   if (var->name != NULL && strcmp(var->name, "gl_FragCoord") == 0) {
+
+      /* Section 4.3.8.1, page 39 of GLSL 1.50 spec says:
+       *
+       *    "Within any shader, the first redeclarations of gl_FragCoord
+       *     must appear before any use of gl_FragCoord."
+       *
+       * Generate a compiler error if above condition is not met by the
+       * fragment shader.
+       */
+      ir_variable *earlier = state->symbols->get_variable("gl_FragCoord");
+      if (earlier != NULL &&
+          earlier->data.used &&
+          !state->fs_redeclares_gl_fragcoord) {
+         _mesa_glsl_error(loc, state,
+                          "gl_FragCoord used before its first redeclaration "
+                          "in fragment shader");
+      }
+
+      /* Make sure all gl_FragCoord redeclarations specify the same layout
+       * qualifiers.
+       */
+      if (is_conflicting_fragcoord_redeclaration(state, qual)) {
+         const char *const qual_string =
+            get_layout_qualifier_string(qual->flags.q.origin_upper_left,
+                                        qual->flags.q.pixel_center_integer);
+
+         const char *const state_string =
+            get_layout_qualifier_string(state->fs_origin_upper_left,
+                                        state->fs_pixel_center_integer);
+
+         _mesa_glsl_error(loc, state,
+                          "gl_FragCoord redeclared with different layout "
+                          "qualifiers (%s) and (%s) ",
+                          state_string,
+                          qual_string);
+      }
+      state->fs_origin_upper_left = qual->flags.q.origin_upper_left;
+      state->fs_pixel_center_integer = qual->flags.q.pixel_center_integer;
+      state->fs_redeclares_gl_fragcoord_with_no_layout_qualifiers =
+         !qual->flags.q.origin_upper_left && !qual->flags.q.pixel_center_integer;
+      state->fs_redeclares_gl_fragcoord =
+         state->fs_origin_upper_left ||
+         state->fs_pixel_center_integer ||
+         state->fs_redeclares_gl_fragcoord_with_no_layout_qualifiers;
+   }
+
+   var->data.pixel_center_integer = qual->flags.q.pixel_center_integer;
+   var->data.origin_upper_left = qual->flags.q.origin_upper_left;
+   if ((qual->flags.q.origin_upper_left || qual->flags.q.pixel_center_integer)
+       && (strcmp(var->name, "gl_FragCoord") != 0)) {
+      const char *const qual_string = (qual->flags.q.origin_upper_left)
+         ? "origin_upper_left" : "pixel_center_integer";
+
+      _mesa_glsl_error(loc, state,
+		       "layout qualifier `%s' can only be applied to "
+		       "fragment shader input `gl_FragCoord'",
+		       qual_string);
+   }
+
+   if (qual->flags.q.explicit_location) {
+      apply_explicit_location(qual, var, state, loc);
+   } else if (qual->flags.q.explicit_index) {
+      if (!qual->flags.q.subroutine_def)
+         _mesa_glsl_error(loc, state,
+                          "explicit index requires explicit location");
+   }
+
+   if (qual->flags.q.explicit_binding) {
+      apply_explicit_binding(state, loc, var, var->type, qual);
+   }
+
+   if (state->stage == MESA_SHADER_GEOMETRY &&
+       qual->flags.q.out && qual->flags.q.stream) {
+      unsigned qual_stream;
+      if (process_qualifier_constant(state, loc, "stream", qual->stream,
+                                     &qual_stream) &&
+          validate_stream_qualifier(loc, state, qual_stream)) {
+         var->data.stream = qual_stream;
+      }
+   }
+
+   if (var->type->contains_atomic()) {
+      if (var->data.mode == ir_var_uniform) {
+         if (var->data.explicit_binding) {
+            unsigned *offset =
+               &state->atomic_counter_offsets[var->data.binding];
+
+            if (*offset % ATOMIC_COUNTER_SIZE)
+               _mesa_glsl_error(loc, state,
+                                "misaligned atomic counter offset");
+
+            var->data.offset = *offset;
+            *offset += var->type->atomic_size();
+
+         } else {
+            _mesa_glsl_error(loc, state,
+                             "atomic counters require explicit binding point");
+         }
+      } else if (var->data.mode != ir_var_function_in) {
+         _mesa_glsl_error(loc, state, "atomic counters may only be declared as "
+                          "function parameters or uniform-qualified "
+                          "global variables");
+      }
+   }
+
+   /* Is the 'layout' keyword used with parameters that allow relaxed checking.
+    * Many implementations of GL_ARB_fragment_coord_conventions_enable and some
+    * implementations (only Mesa?) GL_ARB_explicit_attrib_location_enable
+    * allowed the layout qualifier to be used with 'varying' and 'attribute'.
+    * These extensions and all following extensions that add the 'layout'
+    * keyword have been modified to require the use of 'in' or 'out'.
+    *
+    * The following extension do not allow the deprecated keywords:
+    *
+    *    GL_AMD_conservative_depth
+    *    GL_ARB_conservative_depth
+    *    GL_ARB_gpu_shader5
+    *    GL_ARB_separate_shader_objects
+    *    GL_ARB_tessellation_shader
+    *    GL_ARB_transform_feedback3
+    *    GL_ARB_uniform_buffer_object
+    *
+    * It is unknown whether GL_EXT_shader_image_load_store or GL_NV_gpu_shader5
+    * allow layout with the deprecated keywords.
+    */
+   const bool relaxed_layout_qualifier_checking =
+      state->ARB_fragment_coord_conventions_enable;
+
+   const bool uses_deprecated_qualifier = qual->flags.q.attribute
+      || qual->flags.q.varying;
+   if (qual->has_layout() && uses_deprecated_qualifier) {
+      if (relaxed_layout_qualifier_checking) {
+         _mesa_glsl_warning(loc, state,
+                            "`layout' qualifier may not be used with "
+                            "`attribute' or `varying'");
+      } else {
+         _mesa_glsl_error(loc, state,
+                          "`layout' qualifier may not be used with "
+                          "`attribute' or `varying'");
+      }
+   }
+
+   /* Layout qualifiers for gl_FragDepth, which are enabled by extension
+    * AMD_conservative_depth.
+    */
+   int depth_layout_count = qual->flags.q.depth_any
+      + qual->flags.q.depth_greater
+      + qual->flags.q.depth_less
+      + qual->flags.q.depth_unchanged;
+   if (depth_layout_count > 0
+       && !state->AMD_conservative_depth_enable
+       && !state->ARB_conservative_depth_enable) {
+       _mesa_glsl_error(loc, state,
+                        "extension GL_AMD_conservative_depth or "
+                        "GL_ARB_conservative_depth must be enabled "
+                        "to use depth layout qualifiers");
+   } else if (depth_layout_count > 0
+              && strcmp(var->name, "gl_FragDepth") != 0) {
+       _mesa_glsl_error(loc, state,
+                        "depth layout qualifiers can be applied only to "
+                        "gl_FragDepth");
+   } else if (depth_layout_count > 1
+              && strcmp(var->name, "gl_FragDepth") == 0) {
+      _mesa_glsl_error(loc, state,
+                       "at most one depth layout qualifier can be applied to "
+                       "gl_FragDepth");
+   }
+   if (qual->flags.q.depth_any)
+      var->data.depth_layout = ir_depth_layout_any;
+   else if (qual->flags.q.depth_greater)
+      var->data.depth_layout = ir_depth_layout_greater;
+   else if (qual->flags.q.depth_less)
+      var->data.depth_layout = ir_depth_layout_less;
+   else if (qual->flags.q.depth_unchanged)
+       var->data.depth_layout = ir_depth_layout_unchanged;
+   else
+       var->data.depth_layout = ir_depth_layout_none;
+
+   if (qual->flags.q.std140 ||
+       qual->flags.q.std430 ||
+       qual->flags.q.packed ||
+       qual->flags.q.shared) {
+      _mesa_glsl_error(loc, state,
+                       "uniform and shader storage block layout qualifiers "
+                       "std140, std430, packed, and shared can only be "
+                       "applied to uniform or shader storage blocks, not "
+                       "members");
+   }
+
+   if (qual->flags.q.row_major || qual->flags.q.column_major) {
+      validate_matrix_layout_for_type(state, loc, var->type, var);
+   }
+
+   /* From section 4.4.1.3 of the GLSL 4.50 specification (Fragment Shader
+    * Inputs):
+    *
+    *  "Fragment shaders also allow the following layout qualifier on in only
+    *   (not with variable declarations)
+    *     layout-qualifier-id
+    *        early_fragment_tests
+    *   [...]"
+    */
+   if (qual->flags.q.early_fragment_tests) {
+      _mesa_glsl_error(loc, state, "early_fragment_tests layout qualifier only "
+                       "valid in fragment shader input layout declaration.");
+   }
+}
+
+static void
+apply_type_qualifier_to_variable(const struct ast_type_qualifier *qual,
+                                 ir_variable *var,
+                                 struct _mesa_glsl_parse_state *state,
+                                 YYLTYPE *loc,
+                                 bool is_parameter)
+{
+   STATIC_ASSERT(sizeof(qual->flags.q) <= sizeof(qual->flags.i));
+
+   if (qual->flags.q.invariant) {
+      if (var->data.used) {
+         _mesa_glsl_error(loc, state,
+                          "variable `%s' may not be redeclared "
+                          "`invariant' after being used",
+                          var->name);
+      } else {
+         var->data.invariant = 1;
+      }
+   }
+
+   if (qual->flags.q.precise) {
+      if (var->data.used) {
+         _mesa_glsl_error(loc, state,
+                          "variable `%s' may not be redeclared "
+                          "`precise' after being used",
+                          var->name);
+      } else {
+         var->data.precise = 1;
+      }
+   }
+
+   if (qual->flags.q.subroutine && !qual->flags.q.uniform) {
+      _mesa_glsl_error(loc, state,
+                       "`subroutine' may only be applied to uniforms, "
+                       "subroutine type declarations, or function definitions");
+   }
+
+   if (qual->flags.q.constant || qual->flags.q.attribute
+       || qual->flags.q.uniform
+       || (qual->flags.q.varying && (state->stage == MESA_SHADER_FRAGMENT)))
+      var->data.read_only = 1;
+
+   if (qual->flags.q.centroid)
+      var->data.centroid = 1;
+
+   if (qual->flags.q.sample)
+      var->data.sample = 1;
+
+   /* Precision qualifiers do not hold any meaning in Desktop GLSL */
+   if (state->es_shader) {
+      var->data.precision =
+         select_gles_precision(qual->precision, var->type, state, loc);
+   }
+
+   if (qual->flags.q.patch)
+      var->data.patch = 1;
+
+   if (qual->flags.q.attribute && state->stage != MESA_SHADER_VERTEX) {
+      var->type = glsl_type::error_type;
+      _mesa_glsl_error(loc, state,
+                       "`attribute' variables may not be declared in the "
+                       "%s shader",
+                       _mesa_shader_stage_to_string(state->stage));
+   }
+
+   /* Disallow layout qualifiers which may only appear on layout declarations. */
+   if (qual->flags.q.prim_type) {
+      _mesa_glsl_error(loc, state,
+                       "Primitive type may only be specified on GS input or output "
+                       "layout declaration, not on variables.");
+   }
+
+   /* Section 6.1.1 (Function Calling Conventions) of the GLSL 1.10 spec says:
+    *
+    *     "However, the const qualifier cannot be used with out or inout."
+    *
+    * The same section of the GLSL 4.40 spec further clarifies this saying:
+    *
+    *     "The const qualifier cannot be used with out or inout, or a
+    *     compile-time error results."
+    */
+   if (is_parameter && qual->flags.q.constant && qual->flags.q.out) {
+      _mesa_glsl_error(loc, state,
+                       "`const' may not be applied to `out' or `inout' "
+                       "function parameters");
+   }
+
+   /* If there is no qualifier that changes the mode of the variable, leave
+    * the setting alone.
+    */
+   assert(var->data.mode != ir_var_temporary);
+   if (qual->flags.q.in && qual->flags.q.out)
+      var->data.mode = ir_var_function_inout;
+   else if (qual->flags.q.in)
+      var->data.mode = is_parameter ? ir_var_function_in : ir_var_shader_in;
+   else if (qual->flags.q.attribute
+	    || (qual->flags.q.varying && (state->stage == MESA_SHADER_FRAGMENT)))
+      var->data.mode = ir_var_shader_in;
+   else if (qual->flags.q.out)
+      var->data.mode = is_parameter ? ir_var_function_out : ir_var_shader_out;
+   else if (qual->flags.q.varying && (state->stage == MESA_SHADER_VERTEX))
+      var->data.mode = ir_var_shader_out;
+   else if (qual->flags.q.uniform)
+      var->data.mode = ir_var_uniform;
+   else if (qual->flags.q.buffer)
+      var->data.mode = ir_var_shader_storage;
+   else if (qual->flags.q.shared_storage)
+      var->data.mode = ir_var_shader_shared;
+
+   if (!is_parameter && is_varying_var(var, state->stage)) {
+      /* User-defined ins/outs are not permitted in compute shaders. */
+      if (state->stage == MESA_SHADER_COMPUTE) {
+         _mesa_glsl_error(loc, state,
+                          "user-defined input and output variables are not "
+                          "permitted in compute shaders");
+      }
+
+      /* This variable is being used to link data between shader stages (in
+       * pre-glsl-1.30 parlance, it's a "varying").  Check that it has a type
+       * that is allowed for such purposes.
+       *
+       * From page 25 (page 31 of the PDF) of the GLSL 1.10 spec:
+       *
+       *     "The varying qualifier can be used only with the data types
+       *     float, vec2, vec3, vec4, mat2, mat3, and mat4, or arrays of
+       *     these."
+       *
+       * This was relaxed in GLSL version 1.30 and GLSL ES version 3.00.  From
+       * page 31 (page 37 of the PDF) of the GLSL 1.30 spec:
+       *
+       *     "Fragment inputs can only be signed and unsigned integers and
+       *     integer vectors, float, floating-point vectors, matrices, or
+       *     arrays of these. Structures cannot be input.
+       *
+       * Similar text exists in the section on vertex shader outputs.
+       *
+       * Similar text exists in the GLSL ES 3.00 spec, except that the GLSL ES
+       * 3.00 spec allows structs as well.  Varying structs are also allowed
+       * in GLSL 1.50.
+       */
+      switch (var->type->get_scalar_type()->base_type) {
+      case GLSL_TYPE_FLOAT:
+         /* Ok in all GLSL versions */
+         break;
+      case GLSL_TYPE_UINT:
+      case GLSL_TYPE_INT:
+         if (state->is_version(130, 300))
+            break;
+         _mesa_glsl_error(loc, state,
+                          "varying variables must be of base type float in %s",
+                          state->get_version_string());
+         break;
+      case GLSL_TYPE_STRUCT:
+         if (state->is_version(150, 300))
+            break;
+         _mesa_glsl_error(loc, state,
+                          "varying variables may not be of type struct");
+         break;
+      case GLSL_TYPE_DOUBLE:
+         break;
+      default:
+         _mesa_glsl_error(loc, state, "illegal type for a varying variable");
+         break;
+      }
+   }
+
+   if (state->all_invariant && (state->current_function == NULL)) {
+      switch (state->stage) {
+      case MESA_SHADER_VERTEX:
+         if (var->data.mode == ir_var_shader_out)
+            var->data.invariant = true;
+         break;
+      case MESA_SHADER_TESS_CTRL:
+      case MESA_SHADER_TESS_EVAL:
+      case MESA_SHADER_GEOMETRY:
+         if ((var->data.mode == ir_var_shader_in)
+             || (var->data.mode == ir_var_shader_out))
+            var->data.invariant = true;
+         break;
+      case MESA_SHADER_FRAGMENT:
+         if (var->data.mode == ir_var_shader_in)
+            var->data.invariant = true;
+         break;
+      case MESA_SHADER_COMPUTE:
+         /* Invariance isn't meaningful in compute shaders. */
+         break;
+      }
+   }
+
+   var->data.interpolation =
+      interpret_interpolation_qualifier(qual, (ir_variable_mode) var->data.mode,
+                                        state, loc);
+
+   /* Does the declaration use the deprecated 'attribute' or 'varying'
+    * keywords?
+    */
+   const bool uses_deprecated_qualifier = qual->flags.q.attribute
+      || qual->flags.q.varying;
+
+
+   /* Validate auxiliary storage qualifiers */
+
+   /* From section 4.3.4 of the GLSL 1.30 spec:
+    *    "It is an error to use centroid in in a vertex shader."
+    *
+    * From section 4.3.4 of the GLSL ES 3.00 spec:
+    *    "It is an error to use centroid in or interpolation qualifiers in
+    *    a vertex shader input."
+    */
+
+   /* Section 4.3.6 of the GLSL 1.30 specification states:
+    * "It is an error to use centroid out in a fragment shader."
+    *
+    * The GL_ARB_shading_language_420pack extension specification states:
+    * "It is an error to use auxiliary storage qualifiers or interpolation
+    *  qualifiers on an output in a fragment shader."
+    */
+   if (qual->flags.q.sample && (!is_varying_var(var, state->stage) || uses_deprecated_qualifier)) {
+      _mesa_glsl_error(loc, state,
+                       "sample qualifier may only be used on `in` or `out` "
+                       "variables between shader stages");
+   }
+   if (qual->flags.q.centroid && !is_varying_var(var, state->stage)) {
+      _mesa_glsl_error(loc, state,
+                       "centroid qualifier may only be used with `in', "
+                       "`out' or `varying' variables between shader stages");
+   }
+
+   if (qual->flags.q.shared_storage && state->stage != MESA_SHADER_COMPUTE) {
+      _mesa_glsl_error(loc, state,
+                       "the shared storage qualifiers can only be used with "
+                       "compute shaders");
+   }
+
+   apply_image_qualifier_to_variable(qual, var, state, loc);
+}
+
+/**
+ * Get the variable that is being redeclared by this declaration
+ *
+ * Semantic checks to verify the validity of the redeclaration are also
+ * performed.  If semantic checks fail, compilation error will be emitted via
+ * \c _mesa_glsl_error, but a non-\c NULL pointer will still be returned.
+ *
+ * \returns
+ * A pointer to an existing variable in the current scope if the declaration
+ * is a redeclaration, \c NULL otherwise.
+ */
+static ir_variable *
+get_variable_being_redeclared(ir_variable *var, YYLTYPE loc,
+                              struct _mesa_glsl_parse_state *state,
+                              bool allow_all_redeclarations)
+{
+   /* Check if this declaration is actually a re-declaration, either to
+    * resize an array or add qualifiers to an existing variable.
+    *
+    * This is allowed for variables in the current scope, or when at
+    * global scope (for built-ins in the implicit outer scope).
+    */
+   ir_variable *earlier = state->symbols->get_variable(var->name);
+   if (earlier == NULL ||
+       (state->current_function != NULL &&
+       !state->symbols->name_declared_this_scope(var->name))) {
+      return NULL;
+   }
+
+
+   /* From page 24 (page 30 of the PDF) of the GLSL 1.50 spec,
+    *
+    * "It is legal to declare an array without a size and then
+    *  later re-declare the same name as an array of the same
+    *  type and specify a size."
+    */
+   if (earlier->type->is_unsized_array() && var->type->is_array()
+       && (var->type->fields.array == earlier->type->fields.array)) {
+      /* FINISHME: This doesn't match the qualifiers on the two
+       * FINISHME: declarations.  It's not 100% clear whether this is
+       * FINISHME: required or not.
+       */
+
+      const unsigned size = unsigned(var->type->array_size());
+      check_builtin_array_max_size(var->name, size, loc, state);
+      if ((size > 0) && (size <= earlier->data.max_array_access)) {
+         _mesa_glsl_error(& loc, state, "array size must be > %u due to "
+                          "previous access",
+                          earlier->data.max_array_access);
+      }
+
+      earlier->type = var->type;
+      delete var;
+      var = NULL;
+   } else if ((state->ARB_fragment_coord_conventions_enable ||
+              state->is_version(150, 0))
+              && strcmp(var->name, "gl_FragCoord") == 0
+              && earlier->type == var->type
+              && var->data.mode == ir_var_shader_in) {
+      /* Allow redeclaration of gl_FragCoord for ARB_fcc layout
+       * qualifiers.
+       */
+      earlier->data.origin_upper_left = var->data.origin_upper_left;
+      earlier->data.pixel_center_integer = var->data.pixel_center_integer;
+
+      /* According to section 4.3.7 of the GLSL 1.30 spec,
+       * the following built-in varaibles can be redeclared with an
+       * interpolation qualifier:
+       *    * gl_FrontColor
+       *    * gl_BackColor
+       *    * gl_FrontSecondaryColor
+       *    * gl_BackSecondaryColor
+       *    * gl_Color
+       *    * gl_SecondaryColor
+       */
+   } else if (state->is_version(130, 0)
+              && (strcmp(var->name, "gl_FrontColor") == 0
+                  || strcmp(var->name, "gl_BackColor") == 0
+                  || strcmp(var->name, "gl_FrontSecondaryColor") == 0
+                  || strcmp(var->name, "gl_BackSecondaryColor") == 0
+                  || strcmp(var->name, "gl_Color") == 0
+                  || strcmp(var->name, "gl_SecondaryColor") == 0)
+              && earlier->type == var->type
+              && earlier->data.mode == var->data.mode) {
+      earlier->data.interpolation = var->data.interpolation;
+
+      /* Layout qualifiers for gl_FragDepth. */
+   } else if ((state->AMD_conservative_depth_enable ||
+               state->ARB_conservative_depth_enable)
+              && strcmp(var->name, "gl_FragDepth") == 0
+              && earlier->type == var->type
+              && earlier->data.mode == var->data.mode) {
+
+      /** From the AMD_conservative_depth spec:
+       *     Within any shader, the first redeclarations of gl_FragDepth
+       *     must appear before any use of gl_FragDepth.
+       */
+      if (earlier->data.used) {
+         _mesa_glsl_error(&loc, state,
+                          "the first redeclaration of gl_FragDepth "
+                          "must appear before any use of gl_FragDepth");
+      }
+
+      /* Prevent inconsistent redeclaration of depth layout qualifier. */
+      if (earlier->data.depth_layout != ir_depth_layout_none
+          && earlier->data.depth_layout != var->data.depth_layout) {
+            _mesa_glsl_error(&loc, state,
+                             "gl_FragDepth: depth layout is declared here "
+                             "as '%s, but it was previously declared as "
+                             "'%s'",
+                             depth_layout_string(var->data.depth_layout),
+                             depth_layout_string(earlier->data.depth_layout));
+      }
+
+      earlier->data.depth_layout = var->data.depth_layout;
+
+   } else if (allow_all_redeclarations) {
+      if (earlier->data.mode != var->data.mode) {
+         _mesa_glsl_error(&loc, state,
+                          "redeclaration of `%s' with incorrect qualifiers",
+                          var->name);
+      } else if (earlier->type != var->type) {
+         _mesa_glsl_error(&loc, state,
+                          "redeclaration of `%s' has incorrect type",
+                          var->name);
+      }
+   } else {
+      _mesa_glsl_error(&loc, state, "`%s' redeclared", var->name);
+   }
+
+   return earlier;
+}
+
+/**
+ * Generate the IR for an initializer in a variable declaration
+ */
+ir_rvalue *
+process_initializer(ir_variable *var, ast_declaration *decl,
+		    ast_fully_specified_type *type,
+		    exec_list *initializer_instructions,
+		    struct _mesa_glsl_parse_state *state)
+{
+   ir_rvalue *result = NULL;
+
+   YYLTYPE initializer_loc = decl->initializer->get_location();
+
+   /* From page 24 (page 30 of the PDF) of the GLSL 1.10 spec:
+    *
+    *    "All uniform variables are read-only and are initialized either
+    *    directly by an application via API commands, or indirectly by
+    *    OpenGL."
+    */
+   if (var->data.mode == ir_var_uniform) {
+      state->check_version(120, 0, &initializer_loc,
+                           "cannot initialize uniform %s",
+                           var->name);
+   }
+
+   /* Section 4.3.7 "Buffer Variables" of the GLSL 4.30 spec:
+    *
+    *    "Buffer variables cannot have initializers."
+    */
+   if (var->data.mode == ir_var_shader_storage) {
+      _mesa_glsl_error(&initializer_loc, state,
+                       "cannot initialize buffer variable %s",
+                       var->name);
+   }
+
+   /* From section 4.1.7 of the GLSL 4.40 spec:
+    *
+    *    "Opaque variables [...] are initialized only through the
+    *     OpenGL API; they cannot be declared with an initializer in a
+    *     shader."
+    */
+   if (var->type->contains_opaque()) {
+      _mesa_glsl_error(&initializer_loc, state,
+                       "cannot initialize opaque variable %s",
+                       var->name);
+   }
+
+   if ((var->data.mode == ir_var_shader_in) && (state->current_function == NULL)) {
+      _mesa_glsl_error(&initializer_loc, state,
+                       "cannot initialize %s shader input / %s %s",
+                       _mesa_shader_stage_to_string(state->stage),
+                       (state->stage == MESA_SHADER_VERTEX)
+                       ? "attribute" : "varying",
+                       var->name);
+   }
+
+   if (var->data.mode == ir_var_shader_out && state->current_function == NULL) {
+      _mesa_glsl_error(&initializer_loc, state,
+                       "cannot initialize %s shader output %s",
+                       _mesa_shader_stage_to_string(state->stage),
+                       var->name);
+   }
+
+   /* If the initializer is an ast_aggregate_initializer, recursively store
+    * type information from the LHS into it, so that its hir() function can do
+    * type checking.
+    */
+   if (decl->initializer->oper == ast_aggregate)
+      _mesa_ast_set_aggregate_type(var->type, decl->initializer);
+
+   ir_dereference *const lhs = new(state) ir_dereference_variable(var);
+   ir_rvalue *rhs = decl->initializer->hir(initializer_instructions, state);
+
+   /* Calculate the constant value if this is a const or uniform
+    * declaration.
+    *
+    * Section 4.3 (Storage Qualifiers) of the GLSL ES 1.00.17 spec says:
+    *
+    *     "Declarations of globals without a storage qualifier, or with
+    *     just the const qualifier, may include initializers, in which case
+    *     they will be initialized before the first line of main() is
+    *     executed.  Such initializers must be a constant expression."
+    *
+    * The same section of the GLSL ES 3.00.4 spec has similar language.
+    */
+   if (type->qualifier.flags.q.constant
+       || type->qualifier.flags.q.uniform
+       || (state->es_shader && state->current_function == NULL)) {
+      ir_rvalue *new_rhs = validate_assignment(state, initializer_loc,
+                                               lhs, rhs, true);
+      if (new_rhs != NULL) {
+         rhs = new_rhs;
+
+         /* Section 4.3.3 (Constant Expressions) of the GLSL ES 3.00.4 spec
+          * says:
+          *
+          *     "A constant expression is one of
+          *
+          *        ...
+          *
+          *        - an expression formed by an operator on operands that are
+          *          all constant expressions, including getting an element of
+          *          a constant array, or a field of a constant structure, or
+          *          components of a constant vector.  However, the sequence
+          *          operator ( , ) and the assignment operators ( =, +=, ...)
+          *          are not included in the operators that can create a
+          *          constant expression."
+          *
+          * Section 12.43 (Sequence operator and constant expressions) says:
+          *
+          *     "Should the following construct be allowed?
+          *
+          *         float a[2,3];
+          *
+          *     The expression within the brackets uses the sequence operator
+          *     (',') and returns the integer 3 so the construct is declaring
+          *     a single-dimensional array of size 3.  In some languages, the
+          *     construct declares a two-dimensional array.  It would be
+          *     preferable to make this construct illegal to avoid confusion.
+          *
+          *     One possibility is to change the definition of the sequence
+          *     operator so that it does not return a constant-expression and
+          *     hence cannot be used to declare an array size.
+          *
+          *     RESOLUTION: The result of a sequence operator is not a
+          *     constant-expression."
+          *
+          * Section 4.3.3 (Constant Expressions) of the GLSL 4.30.9 spec
+          * contains language almost identical to the section 4.3.3 in the
+          * GLSL ES 3.00.4 spec.  This is a new limitation for these GLSL
+          * versions.
+          */
+         ir_constant *constant_value = rhs->constant_expression_value();
+         if (!constant_value ||
+             (state->is_version(430, 300) &&
+              decl->initializer->has_sequence_subexpression())) {
+            const char *const variable_mode =
+               (type->qualifier.flags.q.constant)
+               ? "const"
+               : ((type->qualifier.flags.q.uniform) ? "uniform" : "global");
+
+            /* If ARB_shading_language_420pack is enabled, initializers of
+             * const-qualified local variables do not have to be constant
+             * expressions. Const-qualified global variables must still be
+             * initialized with constant expressions.
+             */
+            if (!state->has_420pack()
+                || state->current_function == NULL) {
+               _mesa_glsl_error(& initializer_loc, state,
+                                "initializer of %s variable `%s' must be a "
+                                "constant expression",
+                                variable_mode,
+                                decl->identifier);
+               if (var->type->is_numeric()) {
+                  /* Reduce cascading errors. */
+                  var->constant_value = type->qualifier.flags.q.constant
+                     ? ir_constant::zero(state, var->type) : NULL;
+               }
+            }
+         } else {
+            rhs = constant_value;
+            var->constant_value = type->qualifier.flags.q.constant
+               ? constant_value : NULL;
+         }
+      } else {
+         if (var->type->is_numeric()) {
+            /* Reduce cascading errors. */
+            var->constant_value = type->qualifier.flags.q.constant
+               ? ir_constant::zero(state, var->type) : NULL;
+         }
+      }
+   }
+
+   if (rhs && !rhs->type->is_error()) {
+      bool temp = var->data.read_only;
+      if (type->qualifier.flags.q.constant)
+         var->data.read_only = false;
+
+      /* Never emit code to initialize a uniform.
+       */
+      const glsl_type *initializer_type;
+      if (!type->qualifier.flags.q.uniform) {
+         do_assignment(initializer_instructions, state,
+                       NULL,
+                       lhs, rhs,
+                       &result, true,
+                       true,
+                       type->get_location());
+         initializer_type = result->type;
+      } else
+         initializer_type = rhs->type;
+
+      var->constant_initializer = rhs->constant_expression_value();
+      var->data.has_initializer = true;
+
+      /* If the declared variable is an unsized array, it must inherrit
+       * its full type from the initializer.  A declaration such as
+       *
+       *     uniform float a[] = float[](1.0, 2.0, 3.0, 3.0);
+       *
+       * becomes
+       *
+       *     uniform float a[4] = float[](1.0, 2.0, 3.0, 3.0);
+       *
+       * The assignment generated in the if-statement (below) will also
+       * automatically handle this case for non-uniforms.
+       *
+       * If the declared variable is not an array, the types must
+       * already match exactly.  As a result, the type assignment
+       * here can be done unconditionally.  For non-uniforms the call
+       * to do_assignment can change the type of the initializer (via
+       * the implicit conversion rules).  For uniforms the initializer
+       * must be a constant expression, and the type of that expression
+       * was validated above.
+       */
+      var->type = initializer_type;
+
+      var->data.read_only = temp;
+   }
+
+   return result;
+}
+
+static void
+validate_layout_qualifier_vertex_count(struct _mesa_glsl_parse_state *state,
+                                       YYLTYPE loc, ir_variable *var,
+                                       unsigned num_vertices,
+                                       unsigned *size,
+                                       const char *var_category)
+{
+   if (var->type->is_unsized_array()) {
+      /* Section 4.3.8.1 (Input Layout Qualifiers) of the GLSL 1.50 spec says:
+       *
+       *   All geometry shader input unsized array declarations will be
+       *   sized by an earlier input layout qualifier, when present, as per
+       *   the following table.
+       *
+       * Followed by a table mapping each allowed input layout qualifier to
+       * the corresponding input length.
+       *
+       * Similarly for tessellation control shader outputs.
+       */
+      if (num_vertices != 0)
+         var->type = glsl_type::get_array_instance(var->type->fields.array,
+                                                   num_vertices);
+   } else {
+      /* Section 4.3.8.1 (Input Layout Qualifiers) of the GLSL 1.50 spec
+       * includes the following examples of compile-time errors:
+       *
+       *   // code sequence within one shader...
+       *   in vec4 Color1[];    // size unknown
+       *   ...Color1.length()...// illegal, length() unknown
+       *   in vec4 Color2[2];   // size is 2
+       *   ...Color1.length()...// illegal, Color1 still has no size
+       *   in vec4 Color3[3];   // illegal, input sizes are inconsistent
+       *   layout(lines) in;    // legal, input size is 2, matching
+       *   in vec4 Color4[3];   // illegal, contradicts layout
+       *   ...
+       *
+       * To detect the case illustrated by Color3, we verify that the size of
+       * an explicitly-sized array matches the size of any previously declared
+       * explicitly-sized array.  To detect the case illustrated by Color4, we
+       * verify that the size of an explicitly-sized array is consistent with
+       * any previously declared input layout.
+       */
+      if (num_vertices != 0 && var->type->length != num_vertices) {
+         _mesa_glsl_error(&loc, state,
+                          "%s size contradicts previously declared layout "
+                          "(size is %u, but layout requires a size of %u)",
+                          var_category, var->type->length, num_vertices);
+      } else if (*size != 0 && var->type->length != *size) {
+         _mesa_glsl_error(&loc, state,
+                          "%s sizes are inconsistent (size is %u, but a "
+                          "previous declaration has size %u)",
+                          var_category, var->type->length, *size);
+      } else {
+         *size = var->type->length;
+      }
+   }
+}
+
+static void
+handle_tess_ctrl_shader_output_decl(struct _mesa_glsl_parse_state *state,
+                                    YYLTYPE loc, ir_variable *var)
+{
+   unsigned num_vertices = 0;
+
+   if (state->tcs_output_vertices_specified) {
+      if (!state->out_qualifier->vertices->
+             process_qualifier_constant(state, "vertices",
+                                        &num_vertices, false)) {
+         return;
+      }
+
+      if (num_vertices > state->Const.MaxPatchVertices) {
+         _mesa_glsl_error(&loc, state, "vertices (%d) exceeds "
+                          "GL_MAX_PATCH_VERTICES", num_vertices);
+         return;
+      }
+   }
+
+   if (!var->type->is_array() && !var->data.patch) {
+      _mesa_glsl_error(&loc, state,
+                       "tessellation control shader outputs must be arrays");
+
+      /* To avoid cascading failures, short circuit the checks below. */
+      return;
+   }
+
+   if (var->data.patch)
+      return;
+
+   validate_layout_qualifier_vertex_count(state, loc, var, num_vertices,
+                                          &state->tcs_output_size,
+                                          "tessellation control shader output");
+}
+
+/**
+ * Do additional processing necessary for tessellation control/evaluation shader
+ * input declarations. This covers both interface block arrays and bare input
+ * variables.
+ */
+static void
+handle_tess_shader_input_decl(struct _mesa_glsl_parse_state *state,
+                              YYLTYPE loc, ir_variable *var)
+{
+   if (!var->type->is_array() && !var->data.patch) {
+      _mesa_glsl_error(&loc, state,
+                       "per-vertex tessellation shader inputs must be arrays");
+      /* Avoid cascading failures. */
+      return;
+   }
+
+   if (var->data.patch)
+      return;
+
+   /* Unsized arrays are implicitly sized to gl_MaxPatchVertices. */
+   if (var->type->is_unsized_array()) {
+      var->type = glsl_type::get_array_instance(var->type->fields.array,
+            state->Const.MaxPatchVertices);
+   }
+}
+
+
+/**
+ * Do additional processing necessary for geometry shader input declarations
+ * (this covers both interface blocks arrays and bare input variables).
+ */
+static void
+handle_geometry_shader_input_decl(struct _mesa_glsl_parse_state *state,
+                                  YYLTYPE loc, ir_variable *var)
+{
+   unsigned num_vertices = 0;
+
+   if (state->gs_input_prim_type_specified) {
+      num_vertices = vertices_per_prim(state->in_qualifier->prim_type);
+   }
+
+   /* Geometry shader input variables must be arrays.  Caller should have
+    * reported an error for this.
+    */
+   if (!var->type->is_array()) {
+      assert(state->error);
+
+      /* To avoid cascading failures, short circuit the checks below. */
+      return;
+   }
+
+   validate_layout_qualifier_vertex_count(state, loc, var, num_vertices,
+                                          &state->gs_input_size,
+                                          "geometry shader input");
+}
+
+void
+validate_identifier(const char *identifier, YYLTYPE loc,
+                    struct _mesa_glsl_parse_state *state)
+{
+   /* From page 15 (page 21 of the PDF) of the GLSL 1.10 spec,
+    *
+    *   "Identifiers starting with "gl_" are reserved for use by
+    *   OpenGL, and may not be declared in a shader as either a
+    *   variable or a function."
+    */
+   if (is_gl_identifier(identifier)) {
+      _mesa_glsl_error(&loc, state,
+                       "identifier `%s' uses reserved `gl_' prefix",
+                       identifier);
+   } else if (strstr(identifier, "__")) {
+      /* From page 14 (page 20 of the PDF) of the GLSL 1.10
+       * spec:
+       *
+       *     "In addition, all identifiers containing two
+       *      consecutive underscores (__) are reserved as
+       *      possible future keywords."
+       *
+       * The intention is that names containing __ are reserved for internal
+       * use by the implementation, and names prefixed with GL_ are reserved
+       * for use by Khronos.  Names simply containing __ are dangerous to use,
+       * but should be allowed.
+       *
+       * A future version of the GLSL specification will clarify this.
+       */
+      _mesa_glsl_warning(&loc, state,
+                         "identifier `%s' uses reserved `__' string",
+                         identifier);
+   }
+}
+
+ir_rvalue *
+ast_declarator_list::hir(exec_list *instructions,
+                         struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = state;
+   const struct glsl_type *decl_type;
+   const char *type_name = NULL;
+   ir_rvalue *result = NULL;
+   YYLTYPE loc = this->get_location();
+
+   /* From page 46 (page 52 of the PDF) of the GLSL 1.50 spec:
+    *
+    *     "To ensure that a particular output variable is invariant, it is
+    *     necessary to use the invariant qualifier. It can either be used to
+    *     qualify a previously declared variable as being invariant
+    *
+    *         invariant gl_Position; // make existing gl_Position be invariant"
+    *
+    * In these cases the parser will set the 'invariant' flag in the declarator
+    * list, and the type will be NULL.
+    */
+   if (this->invariant) {
+      assert(this->type == NULL);
+
+      if (state->current_function != NULL) {
+         _mesa_glsl_error(& loc, state,
+                          "all uses of `invariant' keyword must be at global "
+                          "scope");
+      }
+
+      foreach_list_typed (ast_declaration, decl, link, &this->declarations) {
+         assert(decl->array_specifier == NULL);
+         assert(decl->initializer == NULL);
+
+         ir_variable *const earlier =
+            state->symbols->get_variable(decl->identifier);
+         if (earlier == NULL) {
+            _mesa_glsl_error(& loc, state,
+                             "undeclared variable `%s' cannot be marked "
+                             "invariant", decl->identifier);
+         } else if (!is_varying_var(earlier, state->stage)) {
+            _mesa_glsl_error(&loc, state,
+                             "`%s' cannot be marked invariant; interfaces between "
+                             "shader stages only.", decl->identifier);
+         } else if (earlier->data.used) {
+            _mesa_glsl_error(& loc, state,
+                            "variable `%s' may not be redeclared "
+                            "`invariant' after being used",
+                            earlier->name);
+         } else {
+            earlier->data.invariant = true;
+         }
+      }
+
+      /* Invariant redeclarations do not have r-values.
+       */
+      return NULL;
+   }
+
+   if (this->precise) {
+      assert(this->type == NULL);
+
+      foreach_list_typed (ast_declaration, decl, link, &this->declarations) {
+         assert(decl->array_specifier == NULL);
+         assert(decl->initializer == NULL);
+
+         ir_variable *const earlier =
+            state->symbols->get_variable(decl->identifier);
+         if (earlier == NULL) {
+            _mesa_glsl_error(& loc, state,
+                             "undeclared variable `%s' cannot be marked "
+                             "precise", decl->identifier);
+         } else if (state->current_function != NULL &&
+                    !state->symbols->name_declared_this_scope(decl->identifier)) {
+            /* Note: we have to check if we're in a function, since
+             * builtins are treated as having come from another scope.
+             */
+            _mesa_glsl_error(& loc, state,
+                             "variable `%s' from an outer scope may not be "
+                             "redeclared `precise' in this scope",
+                             earlier->name);
+         } else if (earlier->data.used) {
+            _mesa_glsl_error(& loc, state,
+                             "variable `%s' may not be redeclared "
+                             "`precise' after being used",
+                             earlier->name);
+         } else {
+            earlier->data.precise = true;
+         }
+      }
+
+      /* Precise redeclarations do not have r-values either. */
+      return NULL;
+   }
+
+   assert(this->type != NULL);
+   assert(!this->invariant);
+   assert(!this->precise);
+
+   /* The type specifier may contain a structure definition.  Process that
+    * before any of the variable declarations.
+    */
+   (void) this->type->specifier->hir(instructions, state);
+
+   decl_type = this->type->glsl_type(& type_name, state);
+
+   /* Section 4.3.7 "Buffer Variables" of the GLSL 4.30 spec:
+    *    "Buffer variables may only be declared inside interface blocks
+    *    (section 4.3.9 “Interface Blocks”), which are then referred to as
+    *    shader storage blocks. It is a compile-time error to declare buffer
+    *    variables at global scope (outside a block)."
+    */
+   if (type->qualifier.flags.q.buffer && !decl_type->is_interface()) {
+      _mesa_glsl_error(&loc, state,
+                       "buffer variables cannot be declared outside "
+                       "interface blocks");
+   }
+
+   /* An offset-qualified atomic counter declaration sets the default
+    * offset for the next declaration within the same atomic counter
+    * buffer.
+    */
+   if (decl_type && decl_type->contains_atomic()) {
+      if (type->qualifier.flags.q.explicit_binding &&
+          type->qualifier.flags.q.explicit_offset) {
+         unsigned qual_binding;
+         unsigned qual_offset;
+         if (process_qualifier_constant(state, &loc, "binding",
+                                        type->qualifier.binding,
+                                        &qual_binding)
+             && process_qualifier_constant(state, &loc, "offset",
+                                        type->qualifier.offset,
+                                        &qual_offset)) {
+            state->atomic_counter_offsets[qual_binding] = qual_offset;
+         }
+      }
+   }
+
+   if (this->declarations.is_empty()) {
+      /* If there is no structure involved in the program text, there are two
+       * possible scenarios:
+       *
+       * - The program text contained something like 'vec4;'.  This is an
+       *   empty declaration.  It is valid but weird.  Emit a warning.
+       *
+       * - The program text contained something like 'S;' and 'S' is not the
+       *   name of a known structure type.  This is both invalid and weird.
+       *   Emit an error.
+       *
+       * - The program text contained something like 'mediump float;'
+       *   when the programmer probably meant 'precision mediump
+       *   float;' Emit a warning with a description of what they
+       *   probably meant to do.
+       *
+       * Note that if decl_type is NULL and there is a structure involved,
+       * there must have been some sort of error with the structure.  In this
+       * case we assume that an error was already generated on this line of
+       * code for the structure.  There is no need to generate an additional,
+       * confusing error.
+       */
+      assert(this->type->specifier->structure == NULL || decl_type != NULL
+	     || state->error);
+
+      if (decl_type == NULL) {
+         _mesa_glsl_error(&loc, state,
+                          "invalid type `%s' in empty declaration",
+                          type_name);
+      } else if (decl_type->base_type == GLSL_TYPE_ATOMIC_UINT) {
+         /* Empty atomic counter declarations are allowed and useful
+          * to set the default offset qualifier.
+          */
+         return NULL;
+      } else if (this->type->qualifier.precision != ast_precision_none) {
+         if (this->type->specifier->structure != NULL) {
+            _mesa_glsl_error(&loc, state,
+                             "precision qualifiers can't be applied "
+                             "to structures");
+         } else {
+            static const char *const precision_names[] = {
+               "highp",
+               "highp",
+               "mediump",
+               "lowp"
+            };
+
+            _mesa_glsl_warning(&loc, state,
+                               "empty declaration with precision qualifier, "
+                               "to set the default precision, use "
+                               "`precision %s %s;'",
+                               precision_names[this->type->qualifier.precision],
+                               type_name);
+         }
+      } else if (this->type->specifier->structure == NULL) {
+         _mesa_glsl_warning(&loc, state, "empty declaration");
+      }
+   }
+
+   foreach_list_typed (ast_declaration, decl, link, &this->declarations) {
+      const struct glsl_type *var_type;
+      ir_variable *var;
+      const char *identifier = decl->identifier;
+      /* FINISHME: Emit a warning if a variable declaration shadows a
+       * FINISHME: declaration at a higher scope.
+       */
+
+      if ((decl_type == NULL) || decl_type->is_void()) {
+         if (type_name != NULL) {
+            _mesa_glsl_error(& loc, state,
+                             "invalid type `%s' in declaration of `%s'",
+                             type_name, decl->identifier);
+         } else {
+            _mesa_glsl_error(& loc, state,
+                             "invalid type in declaration of `%s'",
+                             decl->identifier);
+         }
+         continue;
+      }
+
+      if (this->type->qualifier.flags.q.subroutine) {
+         const glsl_type *t;
+         const char *name;
+
+         t = state->symbols->get_type(this->type->specifier->type_name);
+         if (!t)
+            _mesa_glsl_error(& loc, state,
+                             "invalid type in declaration of `%s'",
+                             decl->identifier);
+         name = ralloc_asprintf(ctx, "%s_%s", _mesa_shader_stage_to_subroutine_prefix(state->stage), decl->identifier);
+
+         identifier = name;
+
+      }
+      var_type = process_array_type(&loc, decl_type, decl->array_specifier,
+                                    state);
+
+      var = new(ctx) ir_variable(var_type, identifier, ir_var_auto);
+
+      /* The 'varying in' and 'varying out' qualifiers can only be used with
+       * ARB_geometry_shader4 and EXT_geometry_shader4, which we don't support
+       * yet.
+       */
+      if (this->type->qualifier.flags.q.varying) {
+         if (this->type->qualifier.flags.q.in) {
+            _mesa_glsl_error(& loc, state,
+                             "`varying in' qualifier in declaration of "
+                             "`%s' only valid for geometry shaders using "
+                             "ARB_geometry_shader4 or EXT_geometry_shader4",
+                             decl->identifier);
+         } else if (this->type->qualifier.flags.q.out) {
+            _mesa_glsl_error(& loc, state,
+                             "`varying out' qualifier in declaration of "
+                             "`%s' only valid for geometry shaders using "
+                             "ARB_geometry_shader4 or EXT_geometry_shader4",
+                             decl->identifier);
+         }
+      }
+
+      /* From page 22 (page 28 of the PDF) of the GLSL 1.10 specification;
+       *
+       *     "Global variables can only use the qualifiers const,
+       *     attribute, uniform, or varying. Only one may be
+       *     specified.
+       *
+       *     Local variables can only use the qualifier const."
+       *
+       * This is relaxed in GLSL 1.30 and GLSL ES 3.00.  It is also relaxed by
+       * any extension that adds the 'layout' keyword.
+       */
+      if (!state->is_version(130, 300)
+          && !state->has_explicit_attrib_location()
+          && !state->has_separate_shader_objects()
+          && !state->ARB_fragment_coord_conventions_enable) {
+         if (this->type->qualifier.flags.q.out) {
+            _mesa_glsl_error(& loc, state,
+                             "`out' qualifier in declaration of `%s' "
+                             "only valid for function parameters in %s",
+                             decl->identifier, state->get_version_string());
+         }
+         if (this->type->qualifier.flags.q.in) {
+            _mesa_glsl_error(& loc, state,
+                             "`in' qualifier in declaration of `%s' "
+                             "only valid for function parameters in %s",
+                             decl->identifier, state->get_version_string());
+         }
+         /* FINISHME: Test for other invalid qualifiers. */
+      }
+
+      apply_type_qualifier_to_variable(& this->type->qualifier, var, state,
+				       & loc, false);
+      apply_layout_qualifier_to_variable(&this->type->qualifier, var, state,
+                                         &loc);
+
+      if (this->type->qualifier.flags.q.invariant) {
+         if (!is_varying_var(var, state->stage)) {
+            _mesa_glsl_error(&loc, state,
+                             "`%s' cannot be marked invariant; interfaces between "
+                             "shader stages only", var->name);
+         }
+      }
+
+      if (state->current_function != NULL) {
+         const char *mode = NULL;
+         const char *extra = "";
+
+         /* There is no need to check for 'inout' here because the parser will
+          * only allow that in function parameter lists.
+          */
+         if (this->type->qualifier.flags.q.attribute) {
+            mode = "attribute";
+         } else if (this->type->qualifier.flags.q.subroutine) {
+            mode = "subroutine uniform";
+         } else if (this->type->qualifier.flags.q.uniform) {
+            mode = "uniform";
+         } else if (this->type->qualifier.flags.q.varying) {
+            mode = "varying";
+         } else if (this->type->qualifier.flags.q.in) {
+            mode = "in";
+            extra = " or in function parameter list";
+         } else if (this->type->qualifier.flags.q.out) {
+            mode = "out";
+            extra = " or in function parameter list";
+         }
+
+         if (mode) {
+            _mesa_glsl_error(& loc, state,
+                             "%s variable `%s' must be declared at "
+                             "global scope%s",
+                             mode, var->name, extra);
+         }
+      } else if (var->data.mode == ir_var_shader_in) {
+         var->data.read_only = true;
+
+         if (state->stage == MESA_SHADER_VERTEX) {
+            bool error_emitted = false;
+
+            /* From page 31 (page 37 of the PDF) of the GLSL 1.50 spec:
+             *
+             *    "Vertex shader inputs can only be float, floating-point
+             *    vectors, matrices, signed and unsigned integers and integer
+             *    vectors. Vertex shader inputs can also form arrays of these
+             *    types, but not structures."
+             *
+             * From page 31 (page 27 of the PDF) of the GLSL 1.30 spec:
+             *
+             *    "Vertex shader inputs can only be float, floating-point
+             *    vectors, matrices, signed and unsigned integers and integer
+             *    vectors. They cannot be arrays or structures."
+             *
+             * From page 23 (page 29 of the PDF) of the GLSL 1.20 spec:
+             *
+             *    "The attribute qualifier can be used only with float,
+             *    floating-point vectors, and matrices. Attribute variables
+             *    cannot be declared as arrays or structures."
+             *
+             * From page 33 (page 39 of the PDF) of the GLSL ES 3.00 spec:
+             *
+             *    "Vertex shader inputs can only be float, floating-point
+             *    vectors, matrices, signed and unsigned integers and integer
+             *    vectors. Vertex shader inputs cannot be arrays or
+             *    structures."
+             */
+            const glsl_type *check_type = var->type->without_array();
+
+            switch (check_type->base_type) {
+            case GLSL_TYPE_FLOAT:
+            break;
+            case GLSL_TYPE_UINT:
+            case GLSL_TYPE_INT:
+               if (state->is_version(120, 300))
+                  break;
+            case GLSL_TYPE_DOUBLE:
+               if (check_type->base_type == GLSL_TYPE_DOUBLE && (state->is_version(410, 0) || state->ARB_vertex_attrib_64bit_enable))
+                  break;
+            /* FALLTHROUGH */
+            default:
+               _mesa_glsl_error(& loc, state,
+                                "vertex shader input / attribute cannot have "
+                                "type %s`%s'",
+                                var->type->is_array() ? "array of " : "",
+                                check_type->name);
+               error_emitted = true;
+            }
+
+            if (!error_emitted && var->type->is_array() &&
+                !state->check_version(150, 0, &loc,
+                                      "vertex shader input / attribute "
+                                      "cannot have array type")) {
+               error_emitted = true;
+            }
+         } else if (state->stage == MESA_SHADER_GEOMETRY) {
+            /* From section 4.3.4 (Inputs) of the GLSL 1.50 spec:
+             *
+             *     Geometry shader input variables get the per-vertex values
+             *     written out by vertex shader output variables of the same
+             *     names. Since a geometry shader operates on a set of
+             *     vertices, each input varying variable (or input block, see
+             *     interface blocks below) needs to be declared as an array.
+             */
+            if (!var->type->is_array()) {
+               _mesa_glsl_error(&loc, state,
+                                "geometry shader inputs must be arrays");
+            }
+
+            handle_geometry_shader_input_decl(state, loc, var);
+         } else if (state->stage == MESA_SHADER_FRAGMENT) {
+            /* From section 4.3.4 (Input Variables) of the GLSL ES 3.10 spec:
+             *
+             *     It is a compile-time error to declare a fragment shader
+             *     input with, or that contains, any of the following types:
+             *
+             *     * A boolean type
+             *     * An opaque type
+             *     * An array of arrays
+             *     * An array of structures
+             *     * A structure containing an array
+             *     * A structure containing a structure
+             */
+            if (state->es_shader) {
+               const glsl_type *check_type = var->type->without_array();
+               if (check_type->is_boolean() ||
+                   check_type->contains_opaque()) {
+                  _mesa_glsl_error(&loc, state,
+                                   "fragment shader input cannot have type %s",
+                                   check_type->name);
+               }
+               if (var->type->is_array() &&
+                   var->type->fields.array->is_array()) {
+                  _mesa_glsl_error(&loc, state,
+                                   "%s shader output "
+                                   "cannot have an array of arrays",
+                                   _mesa_shader_stage_to_string(state->stage));
+               }
+               if (var->type->is_array() &&
+                   var->type->fields.array->is_record()) {
+                  _mesa_glsl_error(&loc, state,
+                                   "fragment shader input "
+                                   "cannot have an array of structs");
+               }
+               if (var->type->is_record()) {
+                  for (unsigned i = 0; i < var->type->length; i++) {
+                     if (var->type->fields.structure[i].type->is_array() ||
+                         var->type->fields.structure[i].type->is_record())
+                        _mesa_glsl_error(&loc, state,
+                                         "fragement shader input cannot have "
+                                         "a struct that contains an "
+                                         "array or struct");
+                  }
+               }
+            }
+         } else if (state->stage == MESA_SHADER_TESS_CTRL ||
+                    state->stage == MESA_SHADER_TESS_EVAL) {
+            handle_tess_shader_input_decl(state, loc, var);
+         }
+      } else if (var->data.mode == ir_var_shader_out) {
+         const glsl_type *check_type = var->type->without_array();
+
+         /* From section 4.3.6 (Output variables) of the GLSL 4.40 spec:
+          *
+          *     It is a compile-time error to declare a vertex, tessellation
+          *     evaluation, tessellation control, or geometry shader output
+          *     that contains any of the following:
+          *
+          *     * A Boolean type (bool, bvec2 ...)
+          *     * An opaque type
+          */
+         if (check_type->is_boolean() || check_type->contains_opaque())
+            _mesa_glsl_error(&loc, state,
+                             "%s shader output cannot have type %s",
+                             _mesa_shader_stage_to_string(state->stage),
+                             check_type->name);
+
+         /* From section 4.3.6 (Output variables) of the GLSL 4.40 spec:
+          *
+          *     It is a compile-time error to declare a fragment shader output
+          *     that contains any of the following:
+          *
+          *     * A Boolean type (bool, bvec2 ...)
+          *     * A double-precision scalar or vector (double, dvec2 ...)
+          *     * An opaque type
+          *     * Any matrix type
+          *     * A structure
+          */
+         if (state->stage == MESA_SHADER_FRAGMENT) {
+            if (check_type->is_record() || check_type->is_matrix())
+               _mesa_glsl_error(&loc, state,
+                                "fragment shader output "
+                                "cannot have struct or matrix type");
+            switch (check_type->base_type) {
+            case GLSL_TYPE_UINT:
+            case GLSL_TYPE_INT:
+            case GLSL_TYPE_FLOAT:
+               break;
+            default:
+               _mesa_glsl_error(&loc, state,
+                                "fragment shader output cannot have "
+                                "type %s", check_type->name);
+            }
+         }
+
+         /* From section 4.3.6 (Output Variables) of the GLSL ES 3.10 spec:
+          *
+          *     It is a compile-time error to declare a vertex shader output
+          *     with, or that contains, any of the following types:
+          *
+          *     * A boolean type
+          *     * An opaque type
+          *     * An array of arrays
+          *     * An array of structures
+          *     * A structure containing an array
+          *     * A structure containing a structure
+          *
+          *     It is a compile-time error to declare a fragment shader output
+          *     with, or that contains, any of the following types:
+          *
+          *     * A boolean type
+          *     * An opaque type
+          *     * A matrix
+          *     * A structure
+          *     * An array of array
+          */
+         if (state->es_shader) {
+            if (var->type->is_array() &&
+                var->type->fields.array->is_array()) {
+               _mesa_glsl_error(&loc, state,
+                                "%s shader output "
+                                "cannot have an array of arrays",
+                                _mesa_shader_stage_to_string(state->stage));
+            }
+            if (state->stage == MESA_SHADER_VERTEX) {
+               if (var->type->is_array() &&
+                   var->type->fields.array->is_record()) {
+                  _mesa_glsl_error(&loc, state,
+                                   "vertex shader output "
+                                   "cannot have an array of structs");
+               }
+               if (var->type->is_record()) {
+                  for (unsigned i = 0; i < var->type->length; i++) {
+                     if (var->type->fields.structure[i].type->is_array() ||
+                         var->type->fields.structure[i].type->is_record())
+                        _mesa_glsl_error(&loc, state,
+                                         "vertex shader output cannot have a "
+                                         "struct that contains an "
+                                         "array or struct");
+                  }
+               }
+            }
+         }
+
+         if (state->stage == MESA_SHADER_TESS_CTRL) {
+            handle_tess_ctrl_shader_output_decl(state, loc, var);
+         }
+      } else if (var->type->contains_subroutine()) {
+         /* declare subroutine uniforms as hidden */
+         var->data.how_declared = ir_var_hidden;
+      }
+
+      /* Integer fragment inputs must be qualified with 'flat'.  In GLSL ES,
+       * so must integer vertex outputs.
+       *
+       * From section 4.3.4 ("Inputs") of the GLSL 1.50 spec:
+       *    "Fragment shader inputs that are signed or unsigned integers or
+       *    integer vectors must be qualified with the interpolation qualifier
+       *    flat."
+       *
+       * From section 4.3.4 ("Input Variables") of the GLSL 3.00 ES spec:
+       *    "Fragment shader inputs that are, or contain, signed or unsigned
+       *    integers or integer vectors must be qualified with the
+       *    interpolation qualifier flat."
+       *
+       * From section 4.3.6 ("Output Variables") of the GLSL 3.00 ES spec:
+       *    "Vertex shader outputs that are, or contain, signed or unsigned
+       *    integers or integer vectors must be qualified with the
+       *    interpolation qualifier flat."
+       *
+       * Note that prior to GLSL 1.50, this requirement applied to vertex
+       * outputs rather than fragment inputs.  That creates problems in the
+       * presence of geometry shaders, so we adopt the GLSL 1.50 rule for all
+       * desktop GL shaders.  For GLSL ES shaders, we follow the spec and
+       * apply the restriction to both vertex outputs and fragment inputs.
+       *
+       * Note also that the desktop GLSL specs are missing the text "or
+       * contain"; this is presumably an oversight, since there is no
+       * reasonable way to interpolate a fragment shader input that contains
+       * an integer.
+       */
+      if (state->is_version(130, 300) &&
+          var->type->contains_integer() &&
+          var->data.interpolation != INTERP_QUALIFIER_FLAT &&
+          ((state->stage == MESA_SHADER_FRAGMENT && var->data.mode == ir_var_shader_in)
+           || (state->stage == MESA_SHADER_VERTEX && var->data.mode == ir_var_shader_out
+               && state->es_shader))) {
+         const char *var_type = (state->stage == MESA_SHADER_VERTEX) ?
+            "vertex output" : "fragment input";
+         _mesa_glsl_error(&loc, state, "if a %s is (or contains) "
+                          "an integer, then it must be qualified with 'flat'",
+                          var_type);
+      }
+
+      /* Double fragment inputs must be qualified with 'flat'. */
+      if (var->type->contains_double() &&
+          var->data.interpolation != INTERP_QUALIFIER_FLAT &&
+          state->stage == MESA_SHADER_FRAGMENT &&
+          var->data.mode == ir_var_shader_in) {
+         _mesa_glsl_error(&loc, state, "if a fragment input is (or contains) "
+                          "a double, then it must be qualified with 'flat'",
+                          var_type);
+      }
+
+      /* Interpolation qualifiers cannot be applied to 'centroid' and
+       * 'centroid varying'.
+       *
+       * From page 29 (page 35 of the PDF) of the GLSL 1.30 spec:
+       *    "interpolation qualifiers may only precede the qualifiers in,
+       *    centroid in, out, or centroid out in a declaration. They do not apply
+       *    to the deprecated storage qualifiers varying or centroid varying."
+       *
+       * These deprecated storage qualifiers do not exist in GLSL ES 3.00.
+       */
+      if (state->is_version(130, 0)
+          && this->type->qualifier.has_interpolation()
+          && this->type->qualifier.flags.q.varying) {
+
+         const char *i = this->type->qualifier.interpolation_string();
+         assert(i != NULL);
+         const char *s;
+         if (this->type->qualifier.flags.q.centroid)
+            s = "centroid varying";
+         else
+            s = "varying";
+
+         _mesa_glsl_error(&loc, state,
+                          "qualifier '%s' cannot be applied to the "
+                          "deprecated storage qualifier '%s'", i, s);
+      }
+
+
+      /* Interpolation qualifiers can only apply to vertex shader outputs and
+       * fragment shader inputs.
+       *
+       * From page 29 (page 35 of the PDF) of the GLSL 1.30 spec:
+       *    "Outputs from a vertex shader (out) and inputs to a fragment
+       *    shader (in) can be further qualified with one or more of these
+       *    interpolation qualifiers"
+       *
+       * From page 31 (page 37 of the PDF) of the GLSL ES 3.00 spec:
+       *    "These interpolation qualifiers may only precede the qualifiers
+       *    in, centroid in, out, or centroid out in a declaration. They do
+       *    not apply to inputs into a vertex shader or outputs from a
+       *    fragment shader."
+       */
+      if (state->is_version(130, 300)
+          && this->type->qualifier.has_interpolation()) {
+
+         const char *i = this->type->qualifier.interpolation_string();
+         assert(i != NULL);
+
+         switch (state->stage) {
+         case MESA_SHADER_VERTEX:
+            if (this->type->qualifier.flags.q.in) {
+               _mesa_glsl_error(&loc, state,
+                                "qualifier '%s' cannot be applied to vertex "
+                                "shader inputs", i);
+            }
+            break;
+         case MESA_SHADER_FRAGMENT:
+            if (this->type->qualifier.flags.q.out) {
+               _mesa_glsl_error(&loc, state,
+                                "qualifier '%s' cannot be applied to fragment "
+                                "shader outputs", i);
+            }
+            break;
+         default:
+            break;
+         }
+      }
+
+
+      /* From section 4.3.4 of the GLSL 4.00 spec:
+       *    "Input variables may not be declared using the patch in qualifier
+       *    in tessellation control or geometry shaders."
+       *
+       * From section 4.3.6 of the GLSL 4.00 spec:
+       *    "It is an error to use patch out in a vertex, tessellation
+       *    evaluation, or geometry shader."
+       *
+       * This doesn't explicitly forbid using them in a fragment shader, but
+       * that's probably just an oversight.
+       */
+      if (state->stage != MESA_SHADER_TESS_EVAL
+          && this->type->qualifier.flags.q.patch
+          && this->type->qualifier.flags.q.in) {
+
+         _mesa_glsl_error(&loc, state, "'patch in' can only be used in a "
+                          "tessellation evaluation shader");
+      }
+
+      if (state->stage != MESA_SHADER_TESS_CTRL
+          && this->type->qualifier.flags.q.patch
+          && this->type->qualifier.flags.q.out) {
+
+         _mesa_glsl_error(&loc, state, "'patch out' can only be used in a "
+                          "tessellation control shader");
+      }
+
+      /* Precision qualifiers exists only in GLSL versions 1.00 and >= 1.30.
+       */
+      if (this->type->qualifier.precision != ast_precision_none) {
+         state->check_precision_qualifiers_allowed(&loc);
+      }
+
+
+      /* If a precision qualifier is allowed on a type, it is allowed on
+       * an array of that type.
+       */
+      if (!(this->type->qualifier.precision == ast_precision_none
+          || precision_qualifier_allowed(var->type->without_array()))) {
+
+         _mesa_glsl_error(&loc, state,
+                          "precision qualifiers apply only to floating point"
+                          ", integer and opaque types");
+      }
+
+      /* From section 4.1.7 of the GLSL 4.40 spec:
+       *
+       *    "[Opaque types] can only be declared as function
+       *     parameters or uniform-qualified variables."
+       */
+      if (var_type->contains_opaque() &&
+          !this->type->qualifier.flags.q.uniform) {
+         _mesa_glsl_error(&loc, state,
+                          "opaque variables must be declared uniform");
+      }
+
+      /* Process the initializer and add its instructions to a temporary
+       * list.  This list will be added to the instruction stream (below) after
+       * the declaration is added.  This is done because in some cases (such as
+       * redeclarations) the declaration may not actually be added to the
+       * instruction stream.
+       */
+      exec_list initializer_instructions;
+
+      /* Examine var name here since var may get deleted in the next call */
+      bool var_is_gl_id = is_gl_identifier(var->name);
+
+      ir_variable *earlier =
+         get_variable_being_redeclared(var, decl->get_location(), state,
+                                       false /* allow_all_redeclarations */);
+      if (earlier != NULL) {
+         if (var_is_gl_id &&
+             earlier->data.how_declared == ir_var_declared_in_block) {
+            _mesa_glsl_error(&loc, state,
+                             "`%s' has already been redeclared using "
+                             "gl_PerVertex", earlier->name);
+         }
+         earlier->data.how_declared = ir_var_declared_normally;
+      }
+
+      if (decl->initializer != NULL) {
+         result = process_initializer((earlier == NULL) ? var : earlier,
+                                      decl, this->type,
+                                      &initializer_instructions, state);
+      } else {
+         validate_array_dimensions(var_type, state, &loc);
+      }
+
+      /* From page 23 (page 29 of the PDF) of the GLSL 1.10 spec:
+       *
+       *     "It is an error to write to a const variable outside of
+       *      its declaration, so they must be initialized when
+       *      declared."
+       */
+      if (this->type->qualifier.flags.q.constant && decl->initializer == NULL) {
+         _mesa_glsl_error(& loc, state,
+                          "const declaration of `%s' must be initialized",
+                          decl->identifier);
+      }
+
+      if (state->es_shader) {
+         const glsl_type *const t = (earlier == NULL)
+            ? var->type : earlier->type;
+
+         if (t->is_unsized_array())
+            /* Section 10.17 of the GLSL ES 1.00 specification states that
+             * unsized array declarations have been removed from the language.
+             * Arrays that are sized using an initializer are still explicitly
+             * sized.  However, GLSL ES 1.00 does not allow array
+             * initializers.  That is only allowed in GLSL ES 3.00.
+             *
+             * Section 4.1.9 (Arrays) of the GLSL ES 3.00 spec says:
+             *
+             *     "An array type can also be formed without specifying a size
+             *     if the definition includes an initializer:
+             *
+             *         float x[] = float[2] (1.0, 2.0);     // declares an array of size 2
+             *         float y[] = float[] (1.0, 2.0, 3.0); // declares an array of size 3
+             *
+             *         float a[5];
+             *         float b[] = a;"
+             */
+            _mesa_glsl_error(& loc, state,
+                             "unsized array declarations are not allowed in "
+                             "GLSL ES");
+      }
+
+      /* If the declaration is not a redeclaration, there are a few additional
+       * semantic checks that must be applied.  In addition, variable that was
+       * created for the declaration should be added to the IR stream.
+       */
+      if (earlier == NULL) {
+         validate_identifier(decl->identifier, loc, state);
+
+         /* Add the variable to the symbol table.  Note that the initializer's
+          * IR was already processed earlier (though it hasn't been emitted
+          * yet), without the variable in scope.
+          *
+          * This differs from most C-like languages, but it follows the GLSL
+          * specification.  From page 28 (page 34 of the PDF) of the GLSL 1.50
+          * spec:
+          *
+          *     "Within a declaration, the scope of a name starts immediately
+          *     after the initializer if present or immediately after the name
+          *     being declared if not."
+          */
+         if (!state->symbols->add_variable(var)) {
+            YYLTYPE loc = this->get_location();
+            _mesa_glsl_error(&loc, state, "name `%s' already taken in the "
+                             "current scope", decl->identifier);
+            continue;
+         }
+
+         /* Push the variable declaration to the top.  It means that all the
+          * variable declarations will appear in a funny last-to-first order,
+          * but otherwise we run into trouble if a function is prototyped, a
+          * global var is decled, then the function is defined with usage of
+          * the global var.  See glslparsertest's CorrectModule.frag.
+          */
+         instructions->push_head(var);
+      }
+
+      instructions->append_list(&initializer_instructions);
+   }
+
+
+   /* Generally, variable declarations do not have r-values.  However,
+    * one is used for the declaration in
+    *
+    * while (bool b = some_condition()) {
+    *   ...
+    * }
+    *
+    * so we return the rvalue from the last seen declaration here.
+    */
+   return result;
+}
+
+
+ir_rvalue *
+ast_parameter_declarator::hir(exec_list *instructions,
+                              struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = state;
+   const struct glsl_type *type;
+   const char *name = NULL;
+   YYLTYPE loc = this->get_location();
+
+   type = this->type->glsl_type(& name, state);
+
+   if (type == NULL) {
+      if (name != NULL) {
+         _mesa_glsl_error(& loc, state,
+                          "invalid type `%s' in declaration of `%s'",
+                          name, this->identifier);
+      } else {
+         _mesa_glsl_error(& loc, state,
+                          "invalid type in declaration of `%s'",
+                          this->identifier);
+      }
+
+      type = glsl_type::error_type;
+   }
+
+   /* From page 62 (page 68 of the PDF) of the GLSL 1.50 spec:
+    *
+    *    "Functions that accept no input arguments need not use void in the
+    *    argument list because prototypes (or definitions) are required and
+    *    therefore there is no ambiguity when an empty argument list "( )" is
+    *    declared. The idiom "(void)" as a parameter list is provided for
+    *    convenience."
+    *
+    * Placing this check here prevents a void parameter being set up
+    * for a function, which avoids tripping up checks for main taking
+    * parameters and lookups of an unnamed symbol.
+    */
+   if (type->is_void()) {
+      if (this->identifier != NULL)
+         _mesa_glsl_error(& loc, state,
+                          "named parameter cannot have type `void'");
+
+      is_void = true;
+      return NULL;
+   }
+
+   if (formal_parameter && (this->identifier == NULL)) {
+      _mesa_glsl_error(& loc, state, "formal parameter lacks a name");
+      return NULL;
+   }
+
+   /* This only handles "vec4 foo[..]".  The earlier specifier->glsl_type(...)
+    * call already handled the "vec4[..] foo" case.
+    */
+   type = process_array_type(&loc, type, this->array_specifier, state);
+
+   if (!type->is_error() && type->is_unsized_array()) {
+      _mesa_glsl_error(&loc, state, "arrays passed as parameters must have "
+                       "a declared size");
+      type = glsl_type::error_type;
+   }
+
+   is_void = false;
+   ir_variable *var = new(ctx)
+      ir_variable(type, this->identifier, ir_var_function_in);
+
+   /* Apply any specified qualifiers to the parameter declaration.  Note that
+    * for function parameters the default mode is 'in'.
+    */
+   apply_type_qualifier_to_variable(& this->type->qualifier, var, state, & loc,
+                                    true);
+
+   /* From section 4.1.7 of the GLSL 4.40 spec:
+    *
+    *   "Opaque variables cannot be treated as l-values; hence cannot
+    *    be used as out or inout function parameters, nor can they be
+    *    assigned into."
+    */
+   if ((var->data.mode == ir_var_function_inout || var->data.mode == ir_var_function_out)
+       && type->contains_opaque()) {
+      _mesa_glsl_error(&loc, state, "out and inout parameters cannot "
+                       "contain opaque variables");
+      type = glsl_type::error_type;
+   }
+
+   /* From page 39 (page 45 of the PDF) of the GLSL 1.10 spec:
+    *
+    *    "When calling a function, expressions that do not evaluate to
+    *     l-values cannot be passed to parameters declared as out or inout."
+    *
+    * From page 32 (page 38 of the PDF) of the GLSL 1.10 spec:
+    *
+    *    "Other binary or unary expressions, non-dereferenced arrays,
+    *     function names, swizzles with repeated fields, and constants
+    *     cannot be l-values."
+    *
+    * So for GLSL 1.10, passing an array as an out or inout parameter is not
+    * allowed.  This restriction is removed in GLSL 1.20, and in GLSL ES.
+    */
+   if ((var->data.mode == ir_var_function_inout || var->data.mode == ir_var_function_out)
+       && type->is_array()
+       && !state->check_version(120, 100, &loc,
+                                "arrays cannot be out or inout parameters")) {
+      type = glsl_type::error_type;
+   }
+
+   instructions->push_tail(var);
+
+   /* Parameter declarations do not have r-values.
+    */
+   return NULL;
+}
+
+
+void
+ast_parameter_declarator::parameters_to_hir(exec_list *ast_parameters,
+                                            bool formal,
+                                            exec_list *ir_parameters,
+                                            _mesa_glsl_parse_state *state)
+{
+   ast_parameter_declarator *void_param = NULL;
+   unsigned count = 0;
+
+   foreach_list_typed (ast_parameter_declarator, param, link, ast_parameters) {
+      param->formal_parameter = formal;
+      param->hir(ir_parameters, state);
+
+      if (param->is_void)
+         void_param = param;
+
+      count++;
+   }
+
+   if ((void_param != NULL) && (count > 1)) {
+      YYLTYPE loc = void_param->get_location();
+
+      _mesa_glsl_error(& loc, state,
+                       "`void' parameter must be only parameter");
+   }
+}
+
+
+void
+emit_function(_mesa_glsl_parse_state *state, ir_function *f)
+{
+   /* IR invariants disallow function declarations or definitions
+    * nested within other function definitions.  But there is no
+    * requirement about the relative order of function declarations
+    * and definitions with respect to one another.  So simply insert
+    * the new ir_function block at the end of the toplevel instruction
+    * list.
+    */
+   state->toplevel_ir->push_tail(f);
+}
+
+
+ir_rvalue *
+ast_function::hir(exec_list *instructions,
+                  struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = state;
+   ir_function *f = NULL;
+   ir_function_signature *sig = NULL;
+   exec_list hir_parameters;
+   YYLTYPE loc = this->get_location();
+
+   const char *const name = identifier;
+
+   /* New functions are always added to the top-level IR instruction stream,
+    * so this instruction list pointer is ignored.  See also emit_function
+    * (called below).
+    */
+   (void) instructions;
+
+   /* From page 21 (page 27 of the PDF) of the GLSL 1.20 spec,
+    *
+    *   "Function declarations (prototypes) cannot occur inside of functions;
+    *   they must be at global scope, or for the built-in functions, outside
+    *   the global scope."
+    *
+    * From page 27 (page 33 of the PDF) of the GLSL ES 1.00.16 spec,
+    *
+    *   "User defined functions may only be defined within the global scope."
+    *
+    * Note that this language does not appear in GLSL 1.10.
+    */
+   if ((state->current_function != NULL) &&
+       state->is_version(120, 100)) {
+      YYLTYPE loc = this->get_location();
+      _mesa_glsl_error(&loc, state,
+		       "declaration of function `%s' not allowed within "
+		       "function body", name);
+   }
+
+   validate_identifier(name, this->get_location(), state);
+
+   /* Convert the list of function parameters to HIR now so that they can be
+    * used below to compare this function's signature with previously seen
+    * signatures for functions with the same name.
+    */
+   ast_parameter_declarator::parameters_to_hir(& this->parameters,
+                                               is_definition,
+                                               & hir_parameters, state);
+
+   const char *return_type_name;
+   const glsl_type *return_type =
+      this->return_type->glsl_type(& return_type_name, state);
+
+   if (!return_type) {
+      YYLTYPE loc = this->get_location();
+      _mesa_glsl_error(&loc, state,
+                       "function `%s' has undeclared return type `%s'",
+                       name, return_type_name);
+      return_type = glsl_type::error_type;
+   }
+
+   /* ARB_shader_subroutine states:
+    *  "Subroutine declarations cannot be prototyped. It is an error to prepend
+    *   subroutine(...) to a function declaration."
+    */
+   if (this->return_type->qualifier.flags.q.subroutine_def && !is_definition) {
+      YYLTYPE loc = this->get_location();
+      _mesa_glsl_error(&loc, state,
+                       "function declaration `%s' cannot have subroutine prepended",
+                       name);
+   }
+
+   /* From page 56 (page 62 of the PDF) of the GLSL 1.30 spec:
+    * "No qualifier is allowed on the return type of a function."
+    */
+   if (this->return_type->has_qualifiers(state)) {
+      YYLTYPE loc = this->get_location();
+      _mesa_glsl_error(& loc, state,
+                       "function `%s' return type has qualifiers", name);
+   }
+
+   /* Section 6.1 (Function Definitions) of the GLSL 1.20 spec says:
+    *
+    *     "Arrays are allowed as arguments and as the return type. In both
+    *     cases, the array must be explicitly sized."
+    */
+   if (return_type->is_unsized_array()) {
+      YYLTYPE loc = this->get_location();
+      _mesa_glsl_error(& loc, state,
+                       "function `%s' return type array must be explicitly "
+                       "sized", name);
+   }
+
+   /* From section 4.1.7 of the GLSL 4.40 spec:
+    *
+    *    "[Opaque types] can only be declared as function parameters
+    *     or uniform-qualified variables."
+    */
+   if (return_type->contains_opaque()) {
+      YYLTYPE loc = this->get_location();
+      _mesa_glsl_error(&loc, state,
+                       "function `%s' return type can't contain an opaque type",
+                       name);
+   }
+
+   /* Create an ir_function if one doesn't already exist. */
+   f = state->symbols->get_function(name);
+   if (f == NULL) {
+      f = new(ctx) ir_function(name);
+      if (!this->return_type->qualifier.flags.q.subroutine) {
+         if (!state->symbols->add_function(f)) {
+            /* This function name shadows a non-function use of the same name. */
+            YYLTYPE loc = this->get_location();
+            _mesa_glsl_error(&loc, state, "function name `%s' conflicts with "
+                             "non-function", name);
+            return NULL;
+         }
+      }
+      emit_function(state, f);
+   }
+
+   /* From GLSL ES 3.0 spec, chapter 6.1 "Function Definitions", page 71:
+    *
+    * "A shader cannot redefine or overload built-in functions."
+    *
+    * While in GLSL ES 1.0 specification, chapter 8 "Built-in Functions":
+    *
+    * "User code can overload the built-in functions but cannot redefine
+    * them."
+    */
+   if (state->es_shader && state->language_version >= 300) {
+      /* Local shader has no exact candidates; check the built-ins. */
+      _mesa_glsl_initialize_builtin_functions();
+      if (_mesa_glsl_find_builtin_function_by_name(name)) {
+         YYLTYPE loc = this->get_location();
+         _mesa_glsl_error(& loc, state,
+                          "A shader cannot redefine or overload built-in "
+                          "function `%s' in GLSL ES 3.00", name);
+         return NULL;
+      }
+   }
+
+   /* Verify that this function's signature either doesn't match a previously
+    * seen signature for a function with the same name, or, if a match is found,
+    * that the previously seen signature does not have an associated definition.
+    */
+   if (state->es_shader || f->has_user_signature()) {
+      sig = f->exact_matching_signature(state, &hir_parameters);
+      if (sig != NULL) {
+         const char *badvar = sig->qualifiers_match(&hir_parameters);
+         if (badvar != NULL) {
+            YYLTYPE loc = this->get_location();
+
+            _mesa_glsl_error(&loc, state, "function `%s' parameter `%s' "
+                             "qualifiers don't match prototype", name, badvar);
+         }
+
+         if (sig->return_type != return_type) {
+            YYLTYPE loc = this->get_location();
+
+            _mesa_glsl_error(&loc, state, "function `%s' return type doesn't "
+                             "match prototype", name);
+         }
+
+         if (sig->is_defined) {
+            if (is_definition) {
+               YYLTYPE loc = this->get_location();
+               _mesa_glsl_error(& loc, state, "function `%s' redefined", name);
+            } else {
+               /* We just encountered a prototype that exactly matches a
+                * function that's already been defined.  This is redundant,
+                * and we should ignore it.
+                */
+               return NULL;
+            }
+         }
+      }
+   }
+
+   /* Verify the return type of main() */
+   if (strcmp(name, "main") == 0) {
+      if (! return_type->is_void()) {
+         YYLTYPE loc = this->get_location();
+
+         _mesa_glsl_error(& loc, state, "main() must return void");
+      }
+
+      if (!hir_parameters.is_empty()) {
+         YYLTYPE loc = this->get_location();
+
+         _mesa_glsl_error(& loc, state, "main() must not take any parameters");
+      }
+   }
+
+   /* Finish storing the information about this new function in its signature.
+    */
+   if (sig == NULL) {
+      sig = new(ctx) ir_function_signature(return_type);
+      f->add_signature(sig);
+   }
+
+   sig->replace_parameters(&hir_parameters);
+   signature = sig;
+
+   if (this->return_type->qualifier.flags.q.subroutine_def) {
+      int idx;
+
+      if (this->return_type->qualifier.flags.q.explicit_index) {
+         unsigned qual_index;
+         if (process_qualifier_constant(state, &loc, "index",
+                                        this->return_type->qualifier.index,
+                                        &qual_index)) {
+            if (!state->has_explicit_uniform_location()) {
+               _mesa_glsl_error(&loc, state, "subroutine index requires "
+                                "GL_ARB_explicit_uniform_location or "
+                                "GLSL 4.30");
+            } else if (qual_index >= MAX_SUBROUTINES) {
+               _mesa_glsl_error(&loc, state,
+                                "invalid subroutine index (%d) index must "
+                                "be a number between 0 and "
+                                "GL_MAX_SUBROUTINES - 1 (%d)", qual_index,
+                                MAX_SUBROUTINES - 1);
+            } else {
+               f->subroutine_index = qual_index;
+            }
+         }
+      }
+
+      f->num_subroutine_types = this->return_type->qualifier.subroutine_list->declarations.length();
+      f->subroutine_types = ralloc_array(state, const struct glsl_type *,
+                                         f->num_subroutine_types);
+      idx = 0;
+      foreach_list_typed(ast_declaration, decl, link, &this->return_type->qualifier.subroutine_list->declarations) {
+         const struct glsl_type *type;
+         /* the subroutine type must be already declared */
+         type = state->symbols->get_type(decl->identifier);
+         if (!type) {
+            _mesa_glsl_error(& loc, state, "unknown type '%s' in subroutine function definition", decl->identifier);
+         }
+         f->subroutine_types[idx++] = type;
+      }
+      state->subroutines = (ir_function **)reralloc(state, state->subroutines,
+                                                    ir_function *,
+                                                    state->num_subroutines + 1);
+      state->subroutines[state->num_subroutines] = f;
+      state->num_subroutines++;
+
+   }
+
+   if (this->return_type->qualifier.flags.q.subroutine) {
+      if (!state->symbols->add_type(this->identifier, glsl_type::get_subroutine_instance(this->identifier))) {
+         _mesa_glsl_error(& loc, state, "type '%s' previously defined", this->identifier);
+         return NULL;
+      }
+      state->subroutine_types = (ir_function **)reralloc(state, state->subroutine_types,
+                                                         ir_function *,
+                                                         state->num_subroutine_types + 1);
+      state->subroutine_types[state->num_subroutine_types] = f;
+      state->num_subroutine_types++;
+
+      f->is_subroutine = true;
+   }
+
+   /* Function declarations (prototypes) do not have r-values.
+    */
+   return NULL;
+}
+
+
+ir_rvalue *
+ast_function_definition::hir(exec_list *instructions,
+                             struct _mesa_glsl_parse_state *state)
+{
+   prototype->is_definition = true;
+   prototype->hir(instructions, state);
+
+   ir_function_signature *signature = prototype->signature;
+   if (signature == NULL)
+      return NULL;
+
+   assert(state->current_function == NULL);
+   state->current_function = signature;
+   state->found_return = false;
+
+   /* Duplicate parameters declared in the prototype as concrete variables.
+    * Add these to the symbol table.
+    */
+   state->symbols->push_scope();
+   foreach_in_list(ir_variable, var, &signature->parameters) {
+      assert(var->as_variable() != NULL);
+
+      /* The only way a parameter would "exist" is if two parameters have
+       * the same name.
+       */
+      if (state->symbols->name_declared_this_scope(var->name)) {
+         YYLTYPE loc = this->get_location();
+
+         _mesa_glsl_error(& loc, state, "parameter `%s' redeclared", var->name);
+      } else {
+         state->symbols->add_variable(var);
+      }
+   }
+
+   /* Convert the body of the function to HIR. */
+   this->body->hir(&signature->body, state);
+   signature->is_defined = true;
+
+   state->symbols->pop_scope();
+
+   assert(state->current_function == signature);
+   state->current_function = NULL;
+
+   if (!signature->return_type->is_void() && !state->found_return) {
+      YYLTYPE loc = this->get_location();
+      _mesa_glsl_error(& loc, state, "function `%s' has non-void return type "
+                       "%s, but no return statement",
+                       signature->function_name(),
+                       signature->return_type->name);
+   }
+
+   /* Function definitions do not have r-values.
+    */
+   return NULL;
+}
+
+
+ir_rvalue *
+ast_jump_statement::hir(exec_list *instructions,
+                        struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = state;
+
+   switch (mode) {
+   case ast_return: {
+      ir_return *inst;
+      assert(state->current_function);
+
+      if (opt_return_value) {
+         ir_rvalue *ret = opt_return_value->hir(instructions, state);
+
+         /* The value of the return type can be NULL if the shader says
+          * 'return foo();' and foo() is a function that returns void.
+          *
+          * NOTE: The GLSL spec doesn't say that this is an error.  The type
+          * of the return value is void.  If the return type of the function is
+          * also void, then this should compile without error.  Seriously.
+          */
+         const glsl_type *const ret_type =
+            (ret == NULL) ? glsl_type::void_type : ret->type;
+
+         /* Implicit conversions are not allowed for return values prior to
+          * ARB_shading_language_420pack.
+          */
+         if (state->current_function->return_type != ret_type) {
+            YYLTYPE loc = this->get_location();
+
+            if (state->has_420pack()) {
+               if (!apply_implicit_conversion(state->current_function->return_type,
+                                              ret, state)) {
+                  _mesa_glsl_error(& loc, state,
+                                   "could not implicitly convert return value "
+                                   "to %s, in function `%s'",
+                                   state->current_function->return_type->name,
+                                   state->current_function->function_name());
+               }
+            } else {
+               _mesa_glsl_error(& loc, state,
+                                "`return' with wrong type %s, in function `%s' "
+                                "returning %s",
+                                ret_type->name,
+                                state->current_function->function_name(),
+                                state->current_function->return_type->name);
+            }
+         } else if (state->current_function->return_type->base_type ==
+                    GLSL_TYPE_VOID) {
+            YYLTYPE loc = this->get_location();
+
+            /* The ARB_shading_language_420pack, GLSL ES 3.0, and GLSL 4.20
+             * specs add a clarification:
+             *
+             *    "A void function can only use return without a return argument, even if
+             *     the return argument has void type. Return statements only accept values:
+             *
+             *         void func1() { }
+             *         void func2() { return func1(); } // illegal return statement"
+             */
+            _mesa_glsl_error(& loc, state,
+                             "void functions can only use `return' without a "
+                             "return argument");
+         }
+
+         inst = new(ctx) ir_return(ret);
+      } else {
+         if (state->current_function->return_type->base_type !=
+             GLSL_TYPE_VOID) {
+            YYLTYPE loc = this->get_location();
+
+            _mesa_glsl_error(& loc, state,
+                             "`return' with no value, in function %s returning "
+                             "non-void",
+            state->current_function->function_name());
+         }
+         inst = new(ctx) ir_return;
+      }
+
+      state->found_return = true;
+      instructions->push_tail(inst);
+      break;
+   }
+
+   case ast_discard:
+      if (state->stage != MESA_SHADER_FRAGMENT) {
+         YYLTYPE loc = this->get_location();
+
+         _mesa_glsl_error(& loc, state,
+                          "`discard' may only appear in a fragment shader");
+      }
+      instructions->push_tail(new(ctx) ir_discard);
+      break;
+
+   case ast_break:
+   case ast_continue:
+      if (mode == ast_continue &&
+          state->loop_nesting_ast == NULL) {
+         YYLTYPE loc = this->get_location();
+
+         _mesa_glsl_error(& loc, state, "continue may only appear in a loop");
+      } else if (mode == ast_break &&
+         state->loop_nesting_ast == NULL &&
+         state->switch_state.switch_nesting_ast == NULL) {
+         YYLTYPE loc = this->get_location();
+
+         _mesa_glsl_error(& loc, state,
+                          "break may only appear in a loop or a switch");
+      } else {
+         /* For a loop, inline the for loop expression again, since we don't
+          * know where near the end of the loop body the normal copy of it is
+          * going to be placed.  Same goes for the condition for a do-while
+          * loop.
+          */
+         if (state->loop_nesting_ast != NULL &&
+             mode == ast_continue && !state->switch_state.is_switch_innermost) {
+            if (state->loop_nesting_ast->rest_expression) {
+               state->loop_nesting_ast->rest_expression->hir(instructions,
+                                                             state);
+            }
+            if (state->loop_nesting_ast->mode ==
+                ast_iteration_statement::ast_do_while) {
+               state->loop_nesting_ast->condition_to_hir(instructions, state);
+            }
+         }
+
+         if (state->switch_state.is_switch_innermost &&
+             mode == ast_continue) {
+            /* Set 'continue_inside' to true. */
+            ir_rvalue *const true_val = new (ctx) ir_constant(true);
+            ir_dereference_variable *deref_continue_inside_var =
+               new(ctx) ir_dereference_variable(state->switch_state.continue_inside);
+            instructions->push_tail(new(ctx) ir_assignment(deref_continue_inside_var,
+                                                           true_val));
+
+            /* Break out from the switch, continue for the loop will
+             * be called right after switch. */
+            ir_loop_jump *const jump =
+               new(ctx) ir_loop_jump(ir_loop_jump::jump_break);
+            instructions->push_tail(jump);
+
+         } else if (state->switch_state.is_switch_innermost &&
+             mode == ast_break) {
+            /* Force break out of switch by inserting a break. */
+            ir_loop_jump *const jump =
+               new(ctx) ir_loop_jump(ir_loop_jump::jump_break);
+            instructions->push_tail(jump);
+         } else {
+            ir_loop_jump *const jump =
+               new(ctx) ir_loop_jump((mode == ast_break)
+                  ? ir_loop_jump::jump_break
+                  : ir_loop_jump::jump_continue);
+            instructions->push_tail(jump);
+         }
+      }
+
+      break;
+   }
+
+   /* Jump instructions do not have r-values.
+    */
+   return NULL;
+}
+
+
+ir_rvalue *
+ast_selection_statement::hir(exec_list *instructions,
+                             struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = state;
+
+   ir_rvalue *const condition = this->condition->hir(instructions, state);
+
+   /* From page 66 (page 72 of the PDF) of the GLSL 1.50 spec:
+    *
+    *    "Any expression whose type evaluates to a Boolean can be used as the
+    *    conditional expression bool-expression. Vector types are not accepted
+    *    as the expression to if."
+    *
+    * The checks are separated so that higher quality diagnostics can be
+    * generated for cases where both rules are violated.
+    */
+   if (!condition->type->is_boolean() || !condition->type->is_scalar()) {
+      YYLTYPE loc = this->condition->get_location();
+
+      _mesa_glsl_error(& loc, state, "if-statement condition must be scalar "
+                       "boolean");
+   }
+
+   ir_if *const stmt = new(ctx) ir_if(condition);
+
+   if (then_statement != NULL) {
+      state->symbols->push_scope();
+      then_statement->hir(& stmt->then_instructions, state);
+      state->symbols->pop_scope();
+   }
+
+   if (else_statement != NULL) {
+      state->symbols->push_scope();
+      else_statement->hir(& stmt->else_instructions, state);
+      state->symbols->pop_scope();
+   }
+
+   instructions->push_tail(stmt);
+
+   /* if-statements do not have r-values.
+    */
+   return NULL;
+}
+
+
+ir_rvalue *
+ast_switch_statement::hir(exec_list *instructions,
+                          struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = state;
+
+   ir_rvalue *const test_expression =
+      this->test_expression->hir(instructions, state);
+
+   /* From page 66 (page 55 of the PDF) of the GLSL 1.50 spec:
+    *
+    *    "The type of init-expression in a switch statement must be a
+    *     scalar integer."
+    */
+   if (!test_expression->type->is_scalar() ||
+       !test_expression->type->is_integer()) {
+      YYLTYPE loc = this->test_expression->get_location();
+
+      _mesa_glsl_error(& loc,
+                       state,
+                       "switch-statement expression must be scalar "
+                       "integer");
+   }
+
+   /* Track the switch-statement nesting in a stack-like manner.
+    */
+   struct glsl_switch_state saved = state->switch_state;
+
+   state->switch_state.is_switch_innermost = true;
+   state->switch_state.switch_nesting_ast = this;
+   state->switch_state.labels_ht = hash_table_ctor(0, hash_table_pointer_hash,
+						   hash_table_pointer_compare);
+   state->switch_state.previous_default = NULL;
+
+   /* Initalize is_fallthru state to false.
+    */
+   ir_rvalue *const is_fallthru_val = new (ctx) ir_constant(false);
+   state->switch_state.is_fallthru_var =
+      new(ctx) ir_variable(glsl_type::bool_type,
+                           "switch_is_fallthru_tmp",
+                           ir_var_temporary);
+   instructions->push_tail(state->switch_state.is_fallthru_var);
+
+   ir_dereference_variable *deref_is_fallthru_var =
+      new(ctx) ir_dereference_variable(state->switch_state.is_fallthru_var);
+   instructions->push_tail(new(ctx) ir_assignment(deref_is_fallthru_var,
+                                                  is_fallthru_val));
+
+   /* Initialize continue_inside state to false.
+    */
+   state->switch_state.continue_inside =
+      new(ctx) ir_variable(glsl_type::bool_type,
+                           "continue_inside_tmp",
+                           ir_var_temporary);
+   instructions->push_tail(state->switch_state.continue_inside);
+
+   ir_rvalue *const false_val = new (ctx) ir_constant(false);
+   ir_dereference_variable *deref_continue_inside_var =
+      new(ctx) ir_dereference_variable(state->switch_state.continue_inside);
+   instructions->push_tail(new(ctx) ir_assignment(deref_continue_inside_var,
+                                                  false_val));
+
+   state->switch_state.run_default =
+      new(ctx) ir_variable(glsl_type::bool_type,
+                             "run_default_tmp",
+                             ir_var_temporary);
+   instructions->push_tail(state->switch_state.run_default);
+
+   /* Loop around the switch is used for flow control. */
+   ir_loop * loop = new(ctx) ir_loop();
+   instructions->push_tail(loop);
+
+   /* Cache test expression.
+    */
+   test_to_hir(&loop->body_instructions, state);
+
+   /* Emit code for body of switch stmt.
+    */
+   body->hir(&loop->body_instructions, state);
+
+   /* Insert a break at the end to exit loop. */
+   ir_loop_jump *jump = new(ctx) ir_loop_jump(ir_loop_jump::jump_break);
+   loop->body_instructions.push_tail(jump);
+
+   /* If we are inside loop, check if continue got called inside switch. */
+   if (state->loop_nesting_ast != NULL) {
+      ir_dereference_variable *deref_continue_inside =
+         new(ctx) ir_dereference_variable(state->switch_state.continue_inside);
+      ir_if *irif = new(ctx) ir_if(deref_continue_inside);
+      ir_loop_jump *jump = new(ctx) ir_loop_jump(ir_loop_jump::jump_continue);
+
+      if (state->loop_nesting_ast != NULL) {
+         if (state->loop_nesting_ast->rest_expression) {
+            state->loop_nesting_ast->rest_expression->hir(&irif->then_instructions,
+                                                          state);
+         }
+         if (state->loop_nesting_ast->mode ==
+             ast_iteration_statement::ast_do_while) {
+            state->loop_nesting_ast->condition_to_hir(&irif->then_instructions, state);
+         }
+      }
+      irif->then_instructions.push_tail(jump);
+      instructions->push_tail(irif);
+   }
+
+   hash_table_dtor(state->switch_state.labels_ht);
+
+   state->switch_state = saved;
+
+   /* Switch statements do not have r-values. */
+   return NULL;
+}
+
+
+void
+ast_switch_statement::test_to_hir(exec_list *instructions,
+                                  struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = state;
+
+   /* Cache value of test expression. */
+   ir_rvalue *const test_val =
+      test_expression->hir(instructions,
+			   state);
+
+   state->switch_state.test_var = new(ctx) ir_variable(test_val->type,
+                                                       "switch_test_tmp",
+                                                       ir_var_temporary);
+   ir_dereference_variable *deref_test_var =
+      new(ctx) ir_dereference_variable(state->switch_state.test_var);
+
+   instructions->push_tail(state->switch_state.test_var);
+   instructions->push_tail(new(ctx) ir_assignment(deref_test_var, test_val));
+}
+
+
+ir_rvalue *
+ast_switch_body::hir(exec_list *instructions,
+                     struct _mesa_glsl_parse_state *state)
+{
+   if (stmts != NULL)
+      stmts->hir(instructions, state);
+
+   /* Switch bodies do not have r-values. */
+   return NULL;
+}
+
+ir_rvalue *
+ast_case_statement_list::hir(exec_list *instructions,
+                             struct _mesa_glsl_parse_state *state)
+{
+   exec_list default_case, after_default, tmp;
+
+   foreach_list_typed (ast_case_statement, case_stmt, link, & this->cases) {
+      case_stmt->hir(&tmp, state);
+
+      /* Default case. */
+      if (state->switch_state.previous_default && default_case.is_empty()) {
+         default_case.append_list(&tmp);
+         continue;
+      }
+
+      /* If default case found, append 'after_default' list. */
+      if (!default_case.is_empty())
+         after_default.append_list(&tmp);
+      else
+         instructions->append_list(&tmp);
+   }
+
+   /* Handle the default case. This is done here because default might not be
+    * the last case. We need to add checks against following cases first to see
+    * if default should be chosen or not.
+    */
+   if (!default_case.is_empty()) {
+
+      ir_rvalue *const true_val = new (state) ir_constant(true);
+      ir_dereference_variable *deref_run_default_var =
+         new(state) ir_dereference_variable(state->switch_state.run_default);
+
+      /* Choose to run default case initially, following conditional
+       * assignments might change this.
+       */
+      ir_assignment *const init_var =
+         new(state) ir_assignment(deref_run_default_var, true_val);
+      instructions->push_tail(init_var);
+
+      /* Default case was the last one, no checks required. */
+      if (after_default.is_empty()) {
+         instructions->append_list(&default_case);
+         return NULL;
+      }
+
+      foreach_in_list(ir_instruction, ir, &after_default) {
+         ir_assignment *assign = ir->as_assignment();
+
+         if (!assign)
+            continue;
+
+         /* Clone the check between case label and init expression. */
+         ir_expression *exp = (ir_expression*) assign->condition;
+         ir_expression *clone = exp->clone(state, NULL);
+
+         ir_dereference_variable *deref_var =
+            new(state) ir_dereference_variable(state->switch_state.run_default);
+         ir_rvalue *const false_val = new (state) ir_constant(false);
+
+         ir_assignment *const set_false =
+            new(state) ir_assignment(deref_var, false_val, clone);
+
+         instructions->push_tail(set_false);
+      }
+
+      /* Append default case and all cases after it. */
+      instructions->append_list(&default_case);
+      instructions->append_list(&after_default);
+   }
+
+   /* Case statements do not have r-values. */
+   return NULL;
+}
+
+ir_rvalue *
+ast_case_statement::hir(exec_list *instructions,
+                        struct _mesa_glsl_parse_state *state)
+{
+   labels->hir(instructions, state);
+
+   /* Guard case statements depending on fallthru state. */
+   ir_dereference_variable *const deref_fallthru_guard =
+      new(state) ir_dereference_variable(state->switch_state.is_fallthru_var);
+   ir_if *const test_fallthru = new(state) ir_if(deref_fallthru_guard);
+
+   foreach_list_typed (ast_node, stmt, link, & this->stmts)
+      stmt->hir(& test_fallthru->then_instructions, state);
+
+   instructions->push_tail(test_fallthru);
+
+   /* Case statements do not have r-values. */
+   return NULL;
+}
+
+
+ir_rvalue *
+ast_case_label_list::hir(exec_list *instructions,
+                         struct _mesa_glsl_parse_state *state)
+{
+   foreach_list_typed (ast_case_label, label, link, & this->labels)
+      label->hir(instructions, state);
+
+   /* Case labels do not have r-values. */
+   return NULL;
+}
+
+ir_rvalue *
+ast_case_label::hir(exec_list *instructions,
+                    struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = state;
+
+   ir_dereference_variable *deref_fallthru_var =
+      new(ctx) ir_dereference_variable(state->switch_state.is_fallthru_var);
+
+   ir_rvalue *const true_val = new(ctx) ir_constant(true);
+
+   /* If not default case, ... */
+   if (this->test_value != NULL) {
+      /* Conditionally set fallthru state based on
+       * comparison of cached test expression value to case label.
+       */
+      ir_rvalue *const label_rval = this->test_value->hir(instructions, state);
+      ir_constant *label_const = label_rval->constant_expression_value();
+
+      if (!label_const) {
+         YYLTYPE loc = this->test_value->get_location();
+
+         _mesa_glsl_error(& loc, state,
+                          "switch statement case label must be a "
+                          "constant expression");
+
+         /* Stuff a dummy value in to allow processing to continue. */
+         label_const = new(ctx) ir_constant(0);
+      } else {
+         ast_expression *previous_label = (ast_expression *)
+         hash_table_find(state->switch_state.labels_ht,
+                         (void *)(uintptr_t)label_const->value.u[0]);
+
+         if (previous_label) {
+            YYLTYPE loc = this->test_value->get_location();
+            _mesa_glsl_error(& loc, state, "duplicate case value");
+
+            loc = previous_label->get_location();
+            _mesa_glsl_error(& loc, state, "this is the previous case label");
+         } else {
+            hash_table_insert(state->switch_state.labels_ht,
+                              this->test_value,
+                              (void *)(uintptr_t)label_const->value.u[0]);
+         }
+      }
+
+      ir_dereference_variable *deref_test_var =
+         new(ctx) ir_dereference_variable(state->switch_state.test_var);
+
+      ir_expression *test_cond = new(ctx) ir_expression(ir_binop_all_equal,
+                                                        label_const,
+                                                        deref_test_var);
+
+      /*
+       * From GLSL 4.40 specification section 6.2 ("Selection"):
+       *
+       *     "The type of the init-expression value in a switch statement must
+       *     be a scalar int or uint. The type of the constant-expression value
+       *     in a case label also must be a scalar int or uint. When any pair
+       *     of these values is tested for "equal value" and the types do not
+       *     match, an implicit conversion will be done to convert the int to a
+       *     uint (see section 4.1.10 “Implicit Conversions”) before the compare
+       *     is done."
+       */
+      if (label_const->type != state->switch_state.test_var->type) {
+         YYLTYPE loc = this->test_value->get_location();
+
+         const glsl_type *type_a = label_const->type;
+         const glsl_type *type_b = state->switch_state.test_var->type;
+
+         /* Check if int->uint implicit conversion is supported. */
+         bool integer_conversion_supported =
+            glsl_type::int_type->can_implicitly_convert_to(glsl_type::uint_type,
+                                                           state);
+
+         if ((!type_a->is_integer() || !type_b->is_integer()) ||
+              !integer_conversion_supported) {
+            _mesa_glsl_error(&loc, state, "type mismatch with switch "
+                             "init-expression and case label (%s != %s)",
+                             type_a->name, type_b->name);
+         } else {
+            /* Conversion of the case label. */
+            if (type_a->base_type == GLSL_TYPE_INT) {
+               if (!apply_implicit_conversion(glsl_type::uint_type,
+                                              test_cond->operands[0], state))
+                  _mesa_glsl_error(&loc, state, "implicit type conversion error");
+            } else {
+               /* Conversion of the init-expression value. */
+               if (!apply_implicit_conversion(glsl_type::uint_type,
+                                              test_cond->operands[1], state))
+                  _mesa_glsl_error(&loc, state, "implicit type conversion error");
+            }
+         }
+      }
+
+      ir_assignment *set_fallthru_on_test =
+         new(ctx) ir_assignment(deref_fallthru_var, true_val, test_cond);
+
+      instructions->push_tail(set_fallthru_on_test);
+   } else { /* default case */
+      if (state->switch_state.previous_default) {
+         YYLTYPE loc = this->get_location();
+         _mesa_glsl_error(& loc, state,
+                          "multiple default labels in one switch");
+
+         loc = state->switch_state.previous_default->get_location();
+         _mesa_glsl_error(& loc, state, "this is the first default label");
+      }
+      state->switch_state.previous_default = this;
+
+      /* Set fallthru condition on 'run_default' bool. */
+      ir_dereference_variable *deref_run_default =
+         new(ctx) ir_dereference_variable(state->switch_state.run_default);
+      ir_rvalue *const cond_true = new(ctx) ir_constant(true);
+      ir_expression *test_cond = new(ctx) ir_expression(ir_binop_all_equal,
+                                                        cond_true,
+                                                        deref_run_default);
+
+      /* Set falltrhu state. */
+      ir_assignment *set_fallthru =
+         new(ctx) ir_assignment(deref_fallthru_var, true_val, test_cond);
+
+      instructions->push_tail(set_fallthru);
+   }
+
+   /* Case statements do not have r-values. */
+   return NULL;
+}
+
+void
+ast_iteration_statement::condition_to_hir(exec_list *instructions,
+                                          struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = state;
+
+   if (condition != NULL) {
+      ir_rvalue *const cond =
+         condition->hir(instructions, state);
+
+      if ((cond == NULL)
+          || !cond->type->is_boolean() || !cond->type->is_scalar()) {
+         YYLTYPE loc = condition->get_location();
+
+         _mesa_glsl_error(& loc, state,
+                          "loop condition must be scalar boolean");
+      } else {
+         /* As the first code in the loop body, generate a block that looks
+          * like 'if (!condition) break;' as the loop termination condition.
+          */
+         ir_rvalue *const not_cond =
+            new(ctx) ir_expression(ir_unop_logic_not, cond);
+
+         ir_if *const if_stmt = new(ctx) ir_if(not_cond);
+
+         ir_jump *const break_stmt =
+            new(ctx) ir_loop_jump(ir_loop_jump::jump_break);
+
+         if_stmt->then_instructions.push_tail(break_stmt);
+         instructions->push_tail(if_stmt);
+      }
+   }
+}
+
+
+ir_rvalue *
+ast_iteration_statement::hir(exec_list *instructions,
+                             struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = state;
+
+   /* For-loops and while-loops start a new scope, but do-while loops do not.
+    */
+   if (mode != ast_do_while)
+      state->symbols->push_scope();
+
+   if (init_statement != NULL)
+      init_statement->hir(instructions, state);
+
+   ir_loop *const stmt = new(ctx) ir_loop();
+   instructions->push_tail(stmt);
+
+   /* Track the current loop nesting. */
+   ast_iteration_statement *nesting_ast = state->loop_nesting_ast;
+
+   state->loop_nesting_ast = this;
+
+   /* Likewise, indicate that following code is closest to a loop,
+    * NOT closest to a switch.
+    */
+   bool saved_is_switch_innermost = state->switch_state.is_switch_innermost;
+   state->switch_state.is_switch_innermost = false;
+
+   if (mode != ast_do_while)
+      condition_to_hir(&stmt->body_instructions, state);
+
+   if (body != NULL)
+      body->hir(& stmt->body_instructions, state);
+
+   if (rest_expression != NULL)
+      rest_expression->hir(& stmt->body_instructions, state);
+
+   if (mode == ast_do_while)
+      condition_to_hir(&stmt->body_instructions, state);
+
+   if (mode != ast_do_while)
+      state->symbols->pop_scope();
+
+   /* Restore previous nesting before returning. */
+   state->loop_nesting_ast = nesting_ast;
+   state->switch_state.is_switch_innermost = saved_is_switch_innermost;
+
+   /* Loops do not have r-values.
+    */
+   return NULL;
+}
+
+
+/**
+ * Determine if the given type is valid for establishing a default precision
+ * qualifier.
+ *
+ * From GLSL ES 3.00 section 4.5.4 ("Default Precision Qualifiers"):
+ *
+ *     "The precision statement
+ *
+ *         precision precision-qualifier type;
+ *
+ *     can be used to establish a default precision qualifier. The type field
+ *     can be either int or float or any of the sampler types, and the
+ *     precision-qualifier can be lowp, mediump, or highp."
+ *
+ * GLSL ES 1.00 has similar language.  GLSL 1.30 doesn't allow precision
+ * qualifiers on sampler types, but this seems like an oversight (since the
+ * intention of including these in GLSL 1.30 is to allow compatibility with ES
+ * shaders).  So we allow int, float, and all sampler types regardless of GLSL
+ * version.
+ */
+static bool
+is_valid_default_precision_type(const struct glsl_type *const type)
+{
+   if (type == NULL)
+      return false;
+
+   switch (type->base_type) {
+   case GLSL_TYPE_INT:
+   case GLSL_TYPE_FLOAT:
+      /* "int" and "float" are valid, but vectors and matrices are not. */
+      return type->vector_elements == 1 && type->matrix_columns == 1;
+   case GLSL_TYPE_SAMPLER:
+   case GLSL_TYPE_IMAGE:
+   case GLSL_TYPE_ATOMIC_UINT:
+      return true;
+   default:
+      return false;
+   }
+}
+
+
+ir_rvalue *
+ast_type_specifier::hir(exec_list *instructions,
+                        struct _mesa_glsl_parse_state *state)
+{
+   if (this->default_precision == ast_precision_none && this->structure == NULL)
+      return NULL;
+
+   YYLTYPE loc = this->get_location();
+
+   /* If this is a precision statement, check that the type to which it is
+    * applied is either float or int.
+    *
+    * From section 4.5.3 of the GLSL 1.30 spec:
+    *    "The precision statement
+    *       precision precision-qualifier type;
+    *    can be used to establish a default precision qualifier. The type
+    *    field can be either int or float [...].  Any other types or
+    *    qualifiers will result in an error.
+    */
+   if (this->default_precision != ast_precision_none) {
+      if (!state->check_precision_qualifiers_allowed(&loc))
+         return NULL;
+
+      if (this->structure != NULL) {
+         _mesa_glsl_error(&loc, state,
+                          "precision qualifiers do not apply to structures");
+         return NULL;
+      }
+
+      if (this->array_specifier != NULL) {
+         _mesa_glsl_error(&loc, state,
+                          "default precision statements do not apply to "
+                          "arrays");
+         return NULL;
+      }
+
+      const struct glsl_type *const type =
+         state->symbols->get_type(this->type_name);
+      if (!is_valid_default_precision_type(type)) {
+         _mesa_glsl_error(&loc, state,
+                          "default precision statements apply only to "
+                          "float, int, and opaque types");
+         return NULL;
+      }
+
+      if (state->es_shader) {
+         /* Section 4.5.3 (Default Precision Qualifiers) of the GLSL ES 1.00
+          * spec says:
+          *
+          *     "Non-precision qualified declarations will use the precision
+          *     qualifier specified in the most recent precision statement
+          *     that is still in scope. The precision statement has the same
+          *     scoping rules as variable declarations. If it is declared
+          *     inside a compound statement, its effect stops at the end of
+          *     the innermost statement it was declared in. Precision
+          *     statements in nested scopes override precision statements in
+          *     outer scopes. Multiple precision statements for the same basic
+          *     type can appear inside the same scope, with later statements
+          *     overriding earlier statements within that scope."
+          *
+          * Default precision specifications follow the same scope rules as
+          * variables.  So, we can track the state of the default precision
+          * qualifiers in the symbol table, and the rules will just work.  This
+          * is a slight abuse of the symbol table, but it has the semantics
+          * that we want.
+          */
+         state->symbols->add_default_precision_qualifier(this->type_name,
+                                                         this->default_precision);
+      }
+
+      /* FINISHME: Translate precision statements into IR. */
+      return NULL;
+   }
+
+   /* _mesa_ast_set_aggregate_type() sets the <structure> field so that
+    * process_record_constructor() can do type-checking on C-style initializer
+    * expressions of structs, but ast_struct_specifier should only be translated
+    * to HIR if it is declaring the type of a structure.
+    *
+    * The ->is_declaration field is false for initializers of variables
+    * declared separately from the struct's type definition.
+    *
+    *    struct S { ... };              (is_declaration = true)
+    *    struct T { ... } t = { ... };  (is_declaration = true)
+    *    S s = { ... };                 (is_declaration = false)
+    */
+   if (this->structure != NULL && this->structure->is_declaration)
+      return this->structure->hir(instructions, state);
+
+   return NULL;
+}
+
+
+/**
+ * Process a structure or interface block tree into an array of structure fields
+ *
+ * After parsing, where there are some syntax differnces, structures and
+ * interface blocks are almost identical.  They are similar enough that the
+ * AST for each can be processed the same way into a set of
+ * \c glsl_struct_field to describe the members.
+ *
+ * If we're processing an interface block, var_mode should be the type of the
+ * interface block (ir_var_shader_in, ir_var_shader_out, ir_var_uniform or
+ * ir_var_shader_storage).  If we're processing a structure, var_mode should be
+ * ir_var_auto.
+ *
+ * \return
+ * The number of fields processed.  A pointer to the array structure fields is
+ * stored in \c *fields_ret.
+ */
+static unsigned
+ast_process_struct_or_iface_block_members(exec_list *instructions,
+                                          struct _mesa_glsl_parse_state *state,
+                                          exec_list *declarations,
+                                          glsl_struct_field **fields_ret,
+                                          bool is_interface,
+                                          enum glsl_matrix_layout matrix_layout,
+                                          bool allow_reserved_names,
+                                          ir_variable_mode var_mode,
+                                          ast_type_qualifier *layout,
+                                          unsigned block_stream,
+                                          unsigned expl_location)
+{
+   unsigned decl_count = 0;
+
+   /* Make an initial pass over the list of fields to determine how
+    * many there are.  Each element in this list is an ast_declarator_list.
+    * This means that we actually need to count the number of elements in the
+    * 'declarations' list in each of the elements.
+    */
+   foreach_list_typed (ast_declarator_list, decl_list, link, declarations) {
+      decl_count += decl_list->declarations.length();
+   }
+
+   /* Allocate storage for the fields and process the field
+    * declarations.  As the declarations are processed, try to also convert
+    * the types to HIR.  This ensures that structure definitions embedded in
+    * other structure definitions or in interface blocks are processed.
+    */
+   glsl_struct_field *const fields = ralloc_array(state, glsl_struct_field,
+                                                  decl_count);
+
+   bool first_member = true;
+   bool first_member_has_explicit_location;
+
+   unsigned i = 0;
+   foreach_list_typed (ast_declarator_list, decl_list, link, declarations) {
+      const char *type_name;
+      YYLTYPE loc = decl_list->get_location();
+
+      decl_list->type->specifier->hir(instructions, state);
+
+      /* Section 10.9 of the GLSL ES 1.00 specification states that
+       * embedded structure definitions have been removed from the language.
+       */
+      if (state->es_shader && decl_list->type->specifier->structure != NULL) {
+         _mesa_glsl_error(&loc, state, "embedded structure definitions are "
+                          "not allowed in GLSL ES 1.00");
+      }
+
+      const glsl_type *decl_type =
+         decl_list->type->glsl_type(& type_name, state);
+
+      const struct ast_type_qualifier *const qual =
+         &decl_list->type->qualifier;
+
+      /* From section 4.3.9 of the GLSL 4.40 spec:
+       *
+       *    "[In interface blocks] opaque types are not allowed."
+       *
+       * It should be impossible for decl_type to be NULL here.  Cases that
+       * might naturally lead to decl_type being NULL, especially for the
+       * is_interface case, will have resulted in compilation having
+       * already halted due to a syntax error.
+       */
+      assert(decl_type);
+
+      if (is_interface && decl_type->contains_opaque()) {
+         _mesa_glsl_error(&loc, state,
+                          "uniform/buffer in non-default interface block contains "
+                          "opaque variable");
+      }
+
+      if (decl_type->contains_atomic()) {
+         /* From section 4.1.7.3 of the GLSL 4.40 spec:
+          *
+          *    "Members of structures cannot be declared as atomic counter
+          *     types."
+          */
+         _mesa_glsl_error(&loc, state, "atomic counter in structure, "
+                          "shader storage block or uniform block");
+      }
+
+      if (decl_type->contains_image()) {
+         /* FINISHME: Same problem as with atomic counters.
+          * FINISHME: Request clarification from Khronos and add
+          * FINISHME: spec quotation here.
+          */
+         _mesa_glsl_error(&loc, state,
+                          "image in structure, shader storage block or "
+                          "uniform block");
+      }
+
+      if (qual->flags.q.explicit_binding) {
+         _mesa_glsl_error(&loc, state,
+                          "binding layout qualifier cannot be applied "
+                          "to struct or interface block members");
+      }
+
+      if (is_interface) {
+         if (!first_member) {
+            if (!layout->flags.q.explicit_location &&
+                ((first_member_has_explicit_location &&
+                  !qual->flags.q.explicit_location) ||
+                 (!first_member_has_explicit_location &&
+                  qual->flags.q.explicit_location))) {
+               _mesa_glsl_error(&loc, state,
+                                "when block-level location layout qualifier "
+                                "is not supplied either all members must "
+                                "have a location layout qualifier or all "
+                                "members must not have a location layout "
+                                "qualifier");
+            }
+         } else {
+            first_member = false;
+            first_member_has_explicit_location =
+               qual->flags.q.explicit_location;
+         }
+      }
+
+      if (qual->flags.q.std140 ||
+          qual->flags.q.std430 ||
+          qual->flags.q.packed ||
+          qual->flags.q.shared) {
+         _mesa_glsl_error(&loc, state,
+                          "uniform/shader storage block layout qualifiers "
+                          "std140, std430, packed, and shared can only be "
+                          "applied to uniform/shader storage blocks, not "
+                          "members");
+      }
+
+      if (qual->flags.q.constant) {
+         _mesa_glsl_error(&loc, state,
+                          "const storage qualifier cannot be applied "
+                          "to struct or interface block members");
+      }
+
+      /* From Section 4.4.2.3 (Geometry Outputs) of the GLSL 4.50 spec:
+       *
+       *   "A block member may be declared with a stream identifier, but
+       *   the specified stream must match the stream associated with the
+       *   containing block."
+       */
+      if (qual->flags.q.explicit_stream) {
+         unsigned qual_stream;
+         if (process_qualifier_constant(state, &loc, "stream",
+                                        qual->stream, &qual_stream) &&
+             qual_stream != block_stream) {
+            _mesa_glsl_error(&loc, state, "stream layout qualifier on "
+                             "interface block member does not match "
+                             "the interface block (%u vs %u)", qual_stream,
+                             block_stream);
+         }
+      }
+
+      if (qual->flags.q.uniform && qual->has_interpolation()) {
+         _mesa_glsl_error(&loc, state,
+                          "interpolation qualifiers cannot be used "
+                          "with uniform interface blocks");
+      }
+
+      if ((qual->flags.q.uniform || !is_interface) &&
+          qual->has_auxiliary_storage()) {
+         _mesa_glsl_error(&loc, state,
+                          "auxiliary storage qualifiers cannot be used "
+                          "in uniform blocks or structures.");
+      }
+
+      if (qual->flags.q.row_major || qual->flags.q.column_major) {
+         if (!qual->flags.q.uniform && !qual->flags.q.buffer) {
+            _mesa_glsl_error(&loc, state,
+                             "row_major and column_major can only be "
+                             "applied to interface blocks");
+         } else
+            validate_matrix_layout_for_type(state, &loc, decl_type, NULL);
+      }
+
+      if (qual->flags.q.read_only && qual->flags.q.write_only) {
+         _mesa_glsl_error(&loc, state, "buffer variable can't be both "
+                          "readonly and writeonly.");
+      }
+
+      foreach_list_typed (ast_declaration, decl, link,
+                          &decl_list->declarations) {
+         YYLTYPE loc = decl->get_location();
+
+         if (!allow_reserved_names)
+            validate_identifier(decl->identifier, loc, state);
+
+         const struct glsl_type *field_type =
+            process_array_type(&loc, decl_type, decl->array_specifier, state);
+         validate_array_dimensions(field_type, state, &loc);
+         fields[i].type = field_type;
+         fields[i].name = decl->identifier;
+         fields[i].interpolation =
+            interpret_interpolation_qualifier(qual, var_mode, state, &loc);
+         fields[i].centroid = qual->flags.q.centroid ? 1 : 0;
+         fields[i].sample = qual->flags.q.sample ? 1 : 0;
+         fields[i].patch = qual->flags.q.patch ? 1 : 0;
+         fields[i].precision = qual->precision;
+
+         if (qual->flags.q.explicit_location) {
+            unsigned qual_location;
+            if (process_qualifier_constant(state, &loc, "location",
+                                           qual->location, &qual_location)) {
+               fields[i].location = VARYING_SLOT_VAR0 + qual_location;
+               expl_location = fields[i].location +
+                  fields[i].type->count_attribute_slots(false);
+            }
+         } else {
+            if (layout && layout->flags.q.explicit_location) {
+               fields[i].location = expl_location;
+               expl_location += fields[i].type->count_attribute_slots(false);
+            } else {
+               fields[i].location = -1;
+            }
+         }
+
+         /* Propogate row- / column-major information down the fields of the
+          * structure or interface block.  Structures need this data because
+          * the structure may contain a structure that contains ... a matrix
+          * that need the proper layout.
+          */
+         if (field_type->without_array()->is_matrix()
+             || field_type->without_array()->is_record()) {
+            /* If no layout is specified for the field, inherit the layout
+             * from the block.
+             */
+            fields[i].matrix_layout = matrix_layout;
+
+            if (qual->flags.q.row_major)
+               fields[i].matrix_layout = GLSL_MATRIX_LAYOUT_ROW_MAJOR;
+            else if (qual->flags.q.column_major)
+               fields[i].matrix_layout = GLSL_MATRIX_LAYOUT_COLUMN_MAJOR;
+
+            /* If we're processing an interface block, the matrix layout must
+             * be decided by this point.
+             */
+            assert(!is_interface
+                   || fields[i].matrix_layout == GLSL_MATRIX_LAYOUT_ROW_MAJOR
+                   || fields[i].matrix_layout == GLSL_MATRIX_LAYOUT_COLUMN_MAJOR);
+         }
+
+         /* Image qualifiers are allowed on buffer variables, which can only
+          * be defined inside shader storage buffer objects
+          */
+         if (layout && var_mode == ir_var_shader_storage) {
+            /* For readonly and writeonly qualifiers the field definition,
+             * if set, overwrites the layout qualifier.
+             */
+            if (qual->flags.q.read_only) {
+               fields[i].image_read_only = true;
+               fields[i].image_write_only = false;
+            } else if (qual->flags.q.write_only) {
+               fields[i].image_read_only = false;
+               fields[i].image_write_only = true;
+            } else {
+               fields[i].image_read_only = layout->flags.q.read_only;
+               fields[i].image_write_only = layout->flags.q.write_only;
+            }
+
+            /* For other qualifiers, we set the flag if either the layout
+             * qualifier or the field qualifier are set
+             */
+            fields[i].image_coherent = qual->flags.q.coherent ||
+                                        layout->flags.q.coherent;
+            fields[i].image_volatile = qual->flags.q._volatile ||
+                                        layout->flags.q._volatile;
+            fields[i].image_restrict = qual->flags.q.restrict_flag ||
+                                        layout->flags.q.restrict_flag;
+         }
+
+         i++;
+      }
+   }
+
+   assert(i == decl_count);
+
+   *fields_ret = fields;
+   return decl_count;
+}
+
+
+ir_rvalue *
+ast_struct_specifier::hir(exec_list *instructions,
+                          struct _mesa_glsl_parse_state *state)
+{
+   YYLTYPE loc = this->get_location();
+
+   /* Section 4.1.8 (Structures) of the GLSL 1.10 spec says:
+    *
+    *     "Anonymous structures are not supported; so embedded structures must
+    *     have a declarator. A name given to an embedded struct is scoped at
+    *     the same level as the struct it is embedded in."
+    *
+    * The same section of the  GLSL 1.20 spec says:
+    *
+    *     "Anonymous structures are not supported. Embedded structures are not
+    *     supported.
+    *
+    *         struct S { float f; };
+    *         struct T {
+    *             S;              // Error: anonymous structures disallowed
+    *             struct { ... }; // Error: embedded structures disallowed
+    *             S s;            // Okay: nested structures with name are allowed
+    *         };"
+    *
+    * The GLSL ES 1.00 and 3.00 specs have similar langauge and examples.  So,
+    * we allow embedded structures in 1.10 only.
+    */
+   if (state->language_version != 110 && state->struct_specifier_depth != 0)
+      _mesa_glsl_error(&loc, state,
+		       "embedded structure declarations are not allowed");
+
+   state->struct_specifier_depth++;
+
+   unsigned expl_location = 0;
+   if (layout && layout->flags.q.explicit_location) {
+      if (!process_qualifier_constant(state, &loc, "location",
+                                      layout->location, &expl_location)) {
+         return NULL;
+      } else {
+         expl_location = VARYING_SLOT_VAR0 + expl_location;
+      }
+   }
+
+   glsl_struct_field *fields;
+   unsigned decl_count =
+      ast_process_struct_or_iface_block_members(instructions,
+                                                state,
+                                                &this->declarations,
+                                                &fields,
+                                                false,
+                                                GLSL_MATRIX_LAYOUT_INHERITED,
+                                                false /* allow_reserved_names */,
+                                                ir_var_auto,
+                                                layout,
+                                                0, /* for interface only */
+                                                expl_location);
+
+   validate_identifier(this->name, loc, state);
+
+   const glsl_type *t =
+      glsl_type::get_record_instance(fields, decl_count, this->name);
+
+   if (!state->symbols->add_type(name, t)) {
+      _mesa_glsl_error(& loc, state, "struct `%s' previously defined", name);
+   } else {
+      const glsl_type **s = reralloc(state, state->user_structures,
+                                     const glsl_type *,
+                                     state->num_user_structures + 1);
+      if (s != NULL) {
+         s[state->num_user_structures] = t;
+         state->user_structures = s;
+         state->num_user_structures++;
+      }
+   }
+
+   state->struct_specifier_depth--;
+
+   /* Structure type definitions do not have r-values.
+    */
+   return NULL;
+}
+
+
+/**
+ * Visitor class which detects whether a given interface block has been used.
+ */
+class interface_block_usage_visitor : public ir_hierarchical_visitor
+{
+public:
+   interface_block_usage_visitor(ir_variable_mode mode, const glsl_type *block)
+      : mode(mode), block(block), found(false)
+   {
+   }
+
+   virtual ir_visitor_status visit(ir_dereference_variable *ir)
+   {
+      if (ir->var->data.mode == mode && ir->var->get_interface_type() == block) {
+         found = true;
+         return visit_stop;
+      }
+      return visit_continue;
+   }
+
+   bool usage_found() const
+   {
+      return this->found;
+   }
+
+private:
+   ir_variable_mode mode;
+   const glsl_type *block;
+   bool found;
+};
+
+static bool
+is_unsized_array_last_element(ir_variable *v)
+{
+   const glsl_type *interface_type = v->get_interface_type();
+   int length = interface_type->length;
+
+   assert(v->type->is_unsized_array());
+
+   /* Check if it is the last element of the interface */
+   if (strcmp(interface_type->fields.structure[length-1].name, v->name) == 0)
+      return true;
+   return false;
+}
+
+ir_rvalue *
+ast_interface_block::hir(exec_list *instructions,
+                         struct _mesa_glsl_parse_state *state)
+{
+   YYLTYPE loc = this->get_location();
+
+   /* Interface blocks must be declared at global scope */
+   if (state->current_function != NULL) {
+      _mesa_glsl_error(&loc, state,
+                       "Interface block `%s' must be declared "
+                       "at global scope",
+                       this->block_name);
+   }
+
+   if (!this->layout.flags.q.buffer &&
+       this->layout.flags.q.std430) {
+      _mesa_glsl_error(&loc, state,
+                       "std430 storage block layout qualifier is supported "
+                       "only for shader storage blocks");
+   }
+
+   /* The ast_interface_block has a list of ast_declarator_lists.  We
+    * need to turn those into ir_variables with an association
+    * with this uniform block.
+    */
+   enum glsl_interface_packing packing;
+   if (this->layout.flags.q.shared) {
+      packing = GLSL_INTERFACE_PACKING_SHARED;
+   } else if (this->layout.flags.q.packed) {
+      packing = GLSL_INTERFACE_PACKING_PACKED;
+   } else if (this->layout.flags.q.std430) {
+      packing = GLSL_INTERFACE_PACKING_STD430;
+   } else {
+      /* The default layout is std140.
+       */
+      packing = GLSL_INTERFACE_PACKING_STD140;
+   }
+
+   ir_variable_mode var_mode;
+   const char *iface_type_name;
+   if (this->layout.flags.q.in) {
+      var_mode = ir_var_shader_in;
+      iface_type_name = "in";
+   } else if (this->layout.flags.q.out) {
+      var_mode = ir_var_shader_out;
+      iface_type_name = "out";
+   } else if (this->layout.flags.q.uniform) {
+      var_mode = ir_var_uniform;
+      iface_type_name = "uniform";
+   } else if (this->layout.flags.q.buffer) {
+      var_mode = ir_var_shader_storage;
+      iface_type_name = "buffer";
+   } else {
+      var_mode = ir_var_auto;
+      iface_type_name = "UNKNOWN";
+      assert(!"interface block layout qualifier not found!");
+   }
+
+   enum glsl_matrix_layout matrix_layout = GLSL_MATRIX_LAYOUT_INHERITED;
+   if (this->layout.flags.q.row_major)
+      matrix_layout = GLSL_MATRIX_LAYOUT_ROW_MAJOR;
+   else if (this->layout.flags.q.column_major)
+      matrix_layout = GLSL_MATRIX_LAYOUT_COLUMN_MAJOR;
+
+   bool redeclaring_per_vertex = strcmp(this->block_name, "gl_PerVertex") == 0;
+   exec_list declared_variables;
+   glsl_struct_field *fields;
+
+   /* Treat an interface block as one level of nesting, so that embedded struct
+    * specifiers will be disallowed.
+    */
+   state->struct_specifier_depth++;
+
+   /* For blocks that accept memory qualifiers (i.e. shader storage), verify
+    * that we don't have incompatible qualifiers
+    */
+   if (this->layout.flags.q.read_only && this->layout.flags.q.write_only) {
+      _mesa_glsl_error(&loc, state,
+                       "Interface block sets both readonly and writeonly");
+   }
+
+   unsigned qual_stream;
+   if (!process_qualifier_constant(state, &loc, "stream", this->layout.stream,
+                                   &qual_stream) ||
+       !validate_stream_qualifier(&loc, state, qual_stream)) {
+      /* If the stream qualifier is invalid it doesn't make sense to continue
+       * on and try to compare stream layouts on member variables against it
+       * so just return early.
+       */
+      return NULL;
+   }
+
+   unsigned expl_location = 0;
+   if (layout.flags.q.explicit_location) {
+      if (!process_qualifier_constant(state, &loc, "location",
+                                      layout.location, &expl_location)) {
+         return NULL;
+      } else {
+         expl_location = VARYING_SLOT_VAR0 + expl_location;
+      }
+   }
+
+   unsigned int num_variables =
+      ast_process_struct_or_iface_block_members(&declared_variables,
+                                                state,
+                                                &this->declarations,
+                                                &fields,
+                                                true,
+                                                matrix_layout,
+                                                redeclaring_per_vertex,
+                                                var_mode,
+                                                &this->layout,
+                                                qual_stream,
+                                                expl_location);
+
+   state->struct_specifier_depth--;
+
+   if (!redeclaring_per_vertex) {
+      validate_identifier(this->block_name, loc, state);
+
+      /* From section 4.3.9 ("Interface Blocks") of the GLSL 4.50 spec:
+       *
+       *     "Block names have no other use within a shader beyond interface
+       *     matching; it is a compile-time error to use a block name at global
+       *     scope for anything other than as a block name."
+       */
+      ir_variable *var = state->symbols->get_variable(this->block_name);
+      if (var && !var->type->is_interface()) {
+         _mesa_glsl_error(&loc, state, "Block name `%s' is "
+                          "already used in the scope.",
+                          this->block_name);
+      }
+   }
+
+   const glsl_type *earlier_per_vertex = NULL;
+   if (redeclaring_per_vertex) {
+      /* Find the previous declaration of gl_PerVertex.  If we're redeclaring
+       * the named interface block gl_in, we can find it by looking at the
+       * previous declaration of gl_in.  Otherwise we can find it by looking
+       * at the previous decalartion of any of the built-in outputs,
+       * e.g. gl_Position.
+       *
+       * Also check that the instance name and array-ness of the redeclaration
+       * are correct.
+       */
+      switch (var_mode) {
+      case ir_var_shader_in:
+         if (ir_variable *earlier_gl_in =
+             state->symbols->get_variable("gl_in")) {
+            earlier_per_vertex = earlier_gl_in->get_interface_type();
+         } else {
+            _mesa_glsl_error(&loc, state,
+                             "redeclaration of gl_PerVertex input not allowed "
+                             "in the %s shader",
+                             _mesa_shader_stage_to_string(state->stage));
+         }
+         if (this->instance_name == NULL ||
+             strcmp(this->instance_name, "gl_in") != 0 || this->array_specifier == NULL ||
+             !this->array_specifier->is_single_dimension()) {
+            _mesa_glsl_error(&loc, state,
+                             "gl_PerVertex input must be redeclared as "
+                             "gl_in[]");
+         }
+         break;
+      case ir_var_shader_out:
+         if (ir_variable *earlier_gl_Position =
+             state->symbols->get_variable("gl_Position")) {
+            earlier_per_vertex = earlier_gl_Position->get_interface_type();
+         } else if (ir_variable *earlier_gl_out =
+               state->symbols->get_variable("gl_out")) {
+            earlier_per_vertex = earlier_gl_out->get_interface_type();
+         } else {
+            _mesa_glsl_error(&loc, state,
+                             "redeclaration of gl_PerVertex output not "
+                             "allowed in the %s shader",
+                             _mesa_shader_stage_to_string(state->stage));
+         }
+         if (state->stage == MESA_SHADER_TESS_CTRL) {
+            if (this->instance_name == NULL ||
+                strcmp(this->instance_name, "gl_out") != 0 || this->array_specifier == NULL) {
+               _mesa_glsl_error(&loc, state,
+                                "gl_PerVertex output must be redeclared as "
+                                "gl_out[]");
+            }
+         } else {
+            if (this->instance_name != NULL) {
+               _mesa_glsl_error(&loc, state,
+                                "gl_PerVertex output may not be redeclared with "
+                                "an instance name");
+            }
+         }
+         break;
+      default:
+         _mesa_glsl_error(&loc, state,
+                          "gl_PerVertex must be declared as an input or an "
+                          "output");
+         break;
+      }
+
+      if (earlier_per_vertex == NULL) {
+         /* An error has already been reported.  Bail out to avoid null
+          * dereferences later in this function.
+          */
+         return NULL;
+      }
+
+      /* Copy locations from the old gl_PerVertex interface block. */
+      for (unsigned i = 0; i < num_variables; i++) {
+         int j = earlier_per_vertex->field_index(fields[i].name);
+         if (j == -1) {
+            _mesa_glsl_error(&loc, state,
+                             "redeclaration of gl_PerVertex must be a subset "
+                             "of the built-in members of gl_PerVertex");
+         } else {
+            fields[i].location =
+               earlier_per_vertex->fields.structure[j].location;
+            fields[i].interpolation =
+               earlier_per_vertex->fields.structure[j].interpolation;
+            fields[i].centroid =
+               earlier_per_vertex->fields.structure[j].centroid;
+            fields[i].sample =
+               earlier_per_vertex->fields.structure[j].sample;
+            fields[i].patch =
+               earlier_per_vertex->fields.structure[j].patch;
+            fields[i].precision =
+               earlier_per_vertex->fields.structure[j].precision;
+         }
+      }
+
+      /* From section 7.1 ("Built-in Language Variables") of the GLSL 4.10
+       * spec:
+       *
+       *     If a built-in interface block is redeclared, it must appear in
+       *     the shader before any use of any member included in the built-in
+       *     declaration, or a compilation error will result.
+       *
+       * This appears to be a clarification to the behaviour established for
+       * gl_PerVertex by GLSL 1.50, therefore we implement this behaviour
+       * regardless of GLSL version.
+       */
+      interface_block_usage_visitor v(var_mode, earlier_per_vertex);
+      v.run(instructions);
+      if (v.usage_found()) {
+         _mesa_glsl_error(&loc, state,
+                          "redeclaration of a built-in interface block must "
+                          "appear before any use of any member of the "
+                          "interface block");
+      }
+   }
+
+   const glsl_type *block_type =
+      glsl_type::get_interface_instance(fields,
+                                        num_variables,
+                                        packing,
+                                        this->block_name);
+
+   if (!state->symbols->add_interface(block_type->name, block_type, var_mode)) {
+      YYLTYPE loc = this->get_location();
+      _mesa_glsl_error(&loc, state, "interface block `%s' with type `%s' "
+                       "already taken in the current scope",
+                       this->block_name, iface_type_name);
+   }
+
+   /* Since interface blocks cannot contain statements, it should be
+    * impossible for the block to generate any instructions.
+    */
+   assert(declared_variables.is_empty());
+
+   /* From section 4.3.4 (Inputs) of the GLSL 1.50 spec:
+    *
+    *     Geometry shader input variables get the per-vertex values written
+    *     out by vertex shader output variables of the same names. Since a
+    *     geometry shader operates on a set of vertices, each input varying
+    *     variable (or input block, see interface blocks below) needs to be
+    *     declared as an array.
+    */
+   if (state->stage == MESA_SHADER_GEOMETRY && this->array_specifier == NULL &&
+       var_mode == ir_var_shader_in) {
+      _mesa_glsl_error(&loc, state, "geometry shader inputs must be arrays");
+   } else if ((state->stage == MESA_SHADER_TESS_CTRL ||
+               state->stage == MESA_SHADER_TESS_EVAL) &&
+              this->array_specifier == NULL &&
+              var_mode == ir_var_shader_in) {
+      _mesa_glsl_error(&loc, state, "per-vertex tessellation shader inputs must be arrays");
+   } else if (state->stage == MESA_SHADER_TESS_CTRL &&
+              this->array_specifier == NULL &&
+              var_mode == ir_var_shader_out) {
+      _mesa_glsl_error(&loc, state, "tessellation control shader outputs must be arrays");
+   }
+
+
+   /* Page 39 (page 45 of the PDF) of section 4.3.7 in the GLSL ES 3.00 spec
+    * says:
+    *
+    *     "If an instance name (instance-name) is used, then it puts all the
+    *     members inside a scope within its own name space, accessed with the
+    *     field selector ( . ) operator (analogously to structures)."
+    */
+   if (this->instance_name) {
+      if (redeclaring_per_vertex) {
+         /* When a built-in in an unnamed interface block is redeclared,
+          * get_variable_being_redeclared() calls
+          * check_builtin_array_max_size() to make sure that built-in array
+          * variables aren't redeclared to illegal sizes.  But we're looking
+          * at a redeclaration of a named built-in interface block.  So we
+          * have to manually call check_builtin_array_max_size() for all parts
+          * of the interface that are arrays.
+          */
+         for (unsigned i = 0; i < num_variables; i++) {
+            if (fields[i].type->is_array()) {
+               const unsigned size = fields[i].type->array_size();
+               check_builtin_array_max_size(fields[i].name, size, loc, state);
+            }
+         }
+      } else {
+         validate_identifier(this->instance_name, loc, state);
+      }
+
+      ir_variable *var;
+
+      if (this->array_specifier != NULL) {
+         const glsl_type *block_array_type =
+            process_array_type(&loc, block_type, this->array_specifier, state);
+
+         /* Section 4.3.7 (Interface Blocks) of the GLSL 1.50 spec says:
+          *
+          *     For uniform blocks declared an array, each individual array
+          *     element corresponds to a separate buffer object backing one
+          *     instance of the block. As the array size indicates the number
+          *     of buffer objects needed, uniform block array declarations
+          *     must specify an array size.
+          *
+          * And a few paragraphs later:
+          *
+          *     Geometry shader input blocks must be declared as arrays and
+          *     follow the array declaration and linking rules for all
+          *     geometry shader inputs. All other input and output block
+          *     arrays must specify an array size.
+          *
+          * The same applies to tessellation shaders.
+          *
+          * The upshot of this is that the only circumstance where an
+          * interface array size *doesn't* need to be specified is on a
+          * geometry shader input, tessellation control shader input,
+          * tessellation control shader output, and tessellation evaluation
+          * shader input.
+          */
+         if (block_array_type->is_unsized_array()) {
+            bool allow_inputs = state->stage == MESA_SHADER_GEOMETRY ||
+                                state->stage == MESA_SHADER_TESS_CTRL ||
+                                state->stage == MESA_SHADER_TESS_EVAL;
+            bool allow_outputs = state->stage == MESA_SHADER_TESS_CTRL;
+
+            if (this->layout.flags.q.in) {
+               if (!allow_inputs)
+                  _mesa_glsl_error(&loc, state,
+                                   "unsized input block arrays not allowed in "
+                                   "%s shader",
+                                   _mesa_shader_stage_to_string(state->stage));
+            } else if (this->layout.flags.q.out) {
+               if (!allow_outputs)
+                  _mesa_glsl_error(&loc, state,
+                                   "unsized output block arrays not allowed in "
+                                   "%s shader",
+                                   _mesa_shader_stage_to_string(state->stage));
+            } else {
+               /* by elimination, this is a uniform block array */
+               _mesa_glsl_error(&loc, state,
+                                "unsized uniform block arrays not allowed in "
+                                "%s shader",
+                                _mesa_shader_stage_to_string(state->stage));
+            }
+         }
+
+         /* From section 4.3.9 (Interface Blocks) of the GLSL ES 3.10 spec:
+          *
+          *     * Arrays of arrays of blocks are not allowed
+          */
+         if (state->es_shader && block_array_type->is_array() &&
+             block_array_type->fields.array->is_array()) {
+            _mesa_glsl_error(&loc, state,
+                             "arrays of arrays interface blocks are "
+                             "not allowed");
+         }
+
+         var = new(state) ir_variable(block_array_type,
+                                      this->instance_name,
+                                      var_mode);
+      } else {
+         var = new(state) ir_variable(block_type,
+                                      this->instance_name,
+                                      var_mode);
+      }
+
+      var->data.matrix_layout = matrix_layout == GLSL_MATRIX_LAYOUT_INHERITED
+         ? GLSL_MATRIX_LAYOUT_COLUMN_MAJOR : matrix_layout;
+
+      if (var_mode == ir_var_shader_in || var_mode == ir_var_uniform)
+         var->data.read_only = true;
+
+      if (state->stage == MESA_SHADER_GEOMETRY && var_mode == ir_var_shader_in)
+         handle_geometry_shader_input_decl(state, loc, var);
+      else if ((state->stage == MESA_SHADER_TESS_CTRL ||
+           state->stage == MESA_SHADER_TESS_EVAL) && var_mode == ir_var_shader_in)
+         handle_tess_shader_input_decl(state, loc, var);
+      else if (state->stage == MESA_SHADER_TESS_CTRL && var_mode == ir_var_shader_out)
+         handle_tess_ctrl_shader_output_decl(state, loc, var);
+
+      for (unsigned i = 0; i < num_variables; i++) {
+         if (fields[i].type->is_unsized_array()) {
+            if (var_mode == ir_var_shader_storage) {
+               if (i != (num_variables - 1)) {
+                  _mesa_glsl_error(&loc, state, "unsized array `%s' definition: "
+                                   "only last member of a shader storage block "
+                                   "can be defined as unsized array",
+                                   fields[i].name);
+               }
+            } else {
+               /* From GLSL ES 3.10 spec, section 4.1.9 "Arrays":
+               *
+               * "If an array is declared as the last member of a shader storage
+               * block and the size is not specified at compile-time, it is
+               * sized at run-time. In all other cases, arrays are sized only
+               * at compile-time."
+               */
+               if (state->es_shader) {
+                  _mesa_glsl_error(&loc, state, "unsized array `%s' definition: "
+                                 "only last member of a shader storage block "
+                                 "can be defined as unsized array",
+                                 fields[i].name);
+               }
+            }
+         }
+      }
+
+      if (ir_variable *earlier =
+          state->symbols->get_variable(this->instance_name)) {
+         if (!redeclaring_per_vertex) {
+            _mesa_glsl_error(&loc, state, "`%s' redeclared",
+                             this->instance_name);
+         }
+         earlier->data.how_declared = ir_var_declared_normally;
+         earlier->type = var->type;
+         earlier->reinit_interface_type(block_type);
+         delete var;
+      } else {
+         if (this->layout.flags.q.explicit_binding) {
+            apply_explicit_binding(state, &loc, var, var->type,
+                                   &this->layout);
+         }
+
+         var->data.stream = qual_stream;
+         if (layout.flags.q.explicit_location) {
+            var->data.location = expl_location;
+            var->data.explicit_location = true;
+         }
+
+         state->symbols->add_variable(var);
+         instructions->push_tail(var);
+      }
+   } else {
+      /* In order to have an array size, the block must also be declared with
+       * an instance name.
+       */
+      assert(this->array_specifier == NULL);
+
+      for (unsigned i = 0; i < num_variables; i++) {
+         ir_variable *var =
+            new(state) ir_variable(fields[i].type,
+                                   ralloc_strdup(state, fields[i].name),
+                                   var_mode);
+         var->data.interpolation = fields[i].interpolation;
+         var->data.centroid = fields[i].centroid;
+         var->data.sample = fields[i].sample;
+         var->data.patch = fields[i].patch;
+         var->data.stream = qual_stream;
+         var->data.location = fields[i].location;
+         if (fields[i].location != -1)
+            var->data.explicit_location = true;
+         var->init_interface_type(block_type);
+
+         if (var_mode == ir_var_shader_in || var_mode == ir_var_uniform)
+            var->data.read_only = true;
+
+         /* Precision qualifiers do not have any meaning in Desktop GLSL */
+         if (state->es_shader) {
+            var->data.precision =
+               select_gles_precision(fields[i].precision, fields[i].type,
+                                     state, &loc);
+         }
+
+         if (fields[i].matrix_layout == GLSL_MATRIX_LAYOUT_INHERITED) {
+            var->data.matrix_layout = matrix_layout == GLSL_MATRIX_LAYOUT_INHERITED
+               ? GLSL_MATRIX_LAYOUT_COLUMN_MAJOR : matrix_layout;
+         } else {
+            var->data.matrix_layout = fields[i].matrix_layout;
+         }
+
+         if (var->data.mode == ir_var_shader_storage) {
+            var->data.image_read_only = fields[i].image_read_only;
+            var->data.image_write_only = fields[i].image_write_only;
+            var->data.image_coherent = fields[i].image_coherent;
+            var->data.image_volatile = fields[i].image_volatile;
+            var->data.image_restrict = fields[i].image_restrict;
+         }
+
+         /* Examine var name here since var may get deleted in the next call */
+         bool var_is_gl_id = is_gl_identifier(var->name);
+
+         if (redeclaring_per_vertex) {
+            ir_variable *earlier =
+               get_variable_being_redeclared(var, loc, state,
+                                             true /* allow_all_redeclarations */);
+            if (!var_is_gl_id || earlier == NULL) {
+               _mesa_glsl_error(&loc, state,
+                                "redeclaration of gl_PerVertex can only "
+                                "include built-in variables");
+            } else if (earlier->data.how_declared == ir_var_declared_normally) {
+               _mesa_glsl_error(&loc, state,
+                                "`%s' has already been redeclared",
+                                earlier->name);
+            } else {
+               earlier->data.how_declared = ir_var_declared_in_block;
+               earlier->reinit_interface_type(block_type);
+            }
+            continue;
+         }
+
+         if (state->symbols->get_variable(var->name) != NULL)
+            _mesa_glsl_error(&loc, state, "`%s' redeclared", var->name);
+
+         /* Propagate the "binding" keyword into this UBO/SSBO's fields.
+          * The UBO declaration itself doesn't get an ir_variable unless it
+          * has an instance name.  This is ugly.
+          */
+         if (this->layout.flags.q.explicit_binding) {
+            apply_explicit_binding(state, &loc, var,
+                                   var->get_interface_type(), &this->layout);
+         }
+
+         if (var->type->is_unsized_array()) {
+            if (var->is_in_shader_storage_block()) {
+               if (!is_unsized_array_last_element(var)) {
+                  _mesa_glsl_error(&loc, state, "unsized array `%s' definition: "
+                                   "only last member of a shader storage block "
+                                   "can be defined as unsized array",
+                                   var->name);
+               }
+               var->data.from_ssbo_unsized_array = true;
+            } else {
+               /* From GLSL ES 3.10 spec, section 4.1.9 "Arrays":
+               *
+               * "If an array is declared as the last member of a shader storage
+               * block and the size is not specified at compile-time, it is
+               * sized at run-time. In all other cases, arrays are sized only
+               * at compile-time."
+               */
+               if (state->es_shader) {
+                  _mesa_glsl_error(&loc, state, "unsized array `%s' definition: "
+                                 "only last member of a shader storage block "
+                                 "can be defined as unsized array",
+                                 var->name);
+               }
+            }
+         }
+
+         state->symbols->add_variable(var);
+         instructions->push_tail(var);
+      }
+
+      if (redeclaring_per_vertex && block_type != earlier_per_vertex) {
+         /* From section 7.1 ("Built-in Language Variables") of the GLSL 4.10 spec:
+          *
+          *     It is also a compilation error ... to redeclare a built-in
+          *     block and then use a member from that built-in block that was
+          *     not included in the redeclaration.
+          *
+          * This appears to be a clarification to the behaviour established
+          * for gl_PerVertex by GLSL 1.50, therefore we implement this
+          * behaviour regardless of GLSL version.
+          *
+          * To prevent the shader from using a member that was not included in
+          * the redeclaration, we disable any ir_variables that are still
+          * associated with the old declaration of gl_PerVertex (since we've
+          * already updated all of the variables contained in the new
+          * gl_PerVertex to point to it).
+          *
+          * As a side effect this will prevent
+          * validate_intrastage_interface_blocks() from getting confused and
+          * thinking there are conflicting definitions of gl_PerVertex in the
+          * shader.
+          */
+         foreach_in_list_safe(ir_instruction, node, instructions) {
+            ir_variable *const var = node->as_variable();
+            if (var != NULL &&
+                var->get_interface_type() == earlier_per_vertex &&
+                var->data.mode == var_mode) {
+               if (var->data.how_declared == ir_var_declared_normally) {
+                  _mesa_glsl_error(&loc, state,
+                                   "redeclaration of gl_PerVertex cannot "
+                                   "follow a redeclaration of `%s'",
+                                   var->name);
+               }
+               state->symbols->disable_variable(var->name);
+               var->remove();
+            }
+         }
+      }
+   }
+
+   return NULL;
+}
+
+
+ir_rvalue *
+ast_tcs_output_layout::hir(exec_list *instructions,
+			  struct _mesa_glsl_parse_state *state)
+{
+   YYLTYPE loc = this->get_location();
+
+   unsigned num_vertices;
+   if (!state->out_qualifier->vertices->
+          process_qualifier_constant(state, "vertices", &num_vertices,
+                                     false)) {
+      /* return here to stop cascading incorrect error messages */
+     return NULL;
+   }
+
+   /* If any shader outputs occurred before this declaration and specified an
+    * array size, make sure the size they specified is consistent with the
+    * primitive type.
+    */
+   if (state->tcs_output_size != 0 && state->tcs_output_size != num_vertices) {
+      _mesa_glsl_error(&loc, state,
+		       "this tessellation control shader output layout "
+		       "specifies %u vertices, but a previous output "
+		       "is declared with size %u",
+		       num_vertices, state->tcs_output_size);
+      return NULL;
+   }
+
+   state->tcs_output_vertices_specified = true;
+
+   /* If any shader outputs occurred before this declaration and did not
+    * specify an array size, their size is determined now.
+    */
+   foreach_in_list (ir_instruction, node, instructions) {
+      ir_variable *var = node->as_variable();
+      if (var == NULL || var->data.mode != ir_var_shader_out)
+	 continue;
+
+      /* Note: Not all tessellation control shader output are arrays. */
+      if (!var->type->is_unsized_array() || var->data.patch)
+         continue;
+
+      if (var->data.max_array_access >= num_vertices) {
+	 _mesa_glsl_error(&loc, state,
+			  "this tessellation control shader output layout "
+			  "specifies %u vertices, but an access to element "
+			  "%u of output `%s' already exists", num_vertices,
+			  var->data.max_array_access, var->name);
+      } else {
+	 var->type = glsl_type::get_array_instance(var->type->fields.array,
+						   num_vertices);
+      }
+   }
+
+   return NULL;
+}
+
+
+ir_rvalue *
+ast_gs_input_layout::hir(exec_list *instructions,
+                         struct _mesa_glsl_parse_state *state)
+{
+   YYLTYPE loc = this->get_location();
+
+   /* If any geometry input layout declaration preceded this one, make sure it
+    * was consistent with this one.
+    */
+   if (state->gs_input_prim_type_specified &&
+       state->in_qualifier->prim_type != this->prim_type) {
+      _mesa_glsl_error(&loc, state,
+                       "geometry shader input layout does not match"
+                       " previous declaration");
+      return NULL;
+   }
+
+   /* If any shader inputs occurred before this declaration and specified an
+    * array size, make sure the size they specified is consistent with the
+    * primitive type.
+    */
+   unsigned num_vertices = vertices_per_prim(this->prim_type);
+   if (state->gs_input_size != 0 && state->gs_input_size != num_vertices) {
+      _mesa_glsl_error(&loc, state,
+                       "this geometry shader input layout implies %u vertices"
+                       " per primitive, but a previous input is declared"
+                       " with size %u", num_vertices, state->gs_input_size);
+      return NULL;
+   }
+
+   state->gs_input_prim_type_specified = true;
+
+   /* If any shader inputs occurred before this declaration and did not
+    * specify an array size, their size is determined now.
+    */
+   foreach_in_list(ir_instruction, node, instructions) {
+      ir_variable *var = node->as_variable();
+      if (var == NULL || var->data.mode != ir_var_shader_in)
+         continue;
+
+      /* Note: gl_PrimitiveIDIn has mode ir_var_shader_in, but it's not an
+       * array; skip it.
+       */
+
+      if (var->type->is_unsized_array()) {
+         if (var->data.max_array_access >= num_vertices) {
+            _mesa_glsl_error(&loc, state,
+                             "this geometry shader input layout implies %u"
+                             " vertices, but an access to element %u of input"
+                             " `%s' already exists", num_vertices,
+                             var->data.max_array_access, var->name);
+         } else {
+            var->type = glsl_type::get_array_instance(var->type->fields.array,
+                                                      num_vertices);
+         }
+      }
+   }
+
+   return NULL;
+}
+
+
+ir_rvalue *
+ast_cs_input_layout::hir(exec_list *instructions,
+                         struct _mesa_glsl_parse_state *state)
+{
+   YYLTYPE loc = this->get_location();
+
+   /* From the ARB_compute_shader specification:
+    *
+    *     If the local size of the shader in any dimension is greater
+    *     than the maximum size supported by the implementation for that
+    *     dimension, a compile-time error results.
+    *
+    * It is not clear from the spec how the error should be reported if
+    * the total size of the work group exceeds
+    * MAX_COMPUTE_WORK_GROUP_INVOCATIONS, but it seems reasonable to
+    * report it at compile time as well.
+    */
+   GLuint64 total_invocations = 1;
+   unsigned qual_local_size[3];
+   for (int i = 0; i < 3; i++) {
+
+      char *local_size_str = ralloc_asprintf(NULL, "invalid local_size_%c",
+                                             'x' + i);
+      /* Infer a local_size of 1 for unspecified dimensions */
+      if (this->local_size[i] == NULL) {
+         qual_local_size[i] = 1;
+      } else if (!this->local_size[i]->
+             process_qualifier_constant(state, local_size_str,
+                                        &qual_local_size[i], false)) {
+         ralloc_free(local_size_str);
+         return NULL;
+      }
+      ralloc_free(local_size_str);
+
+      if (qual_local_size[i] > state->ctx->Const.MaxComputeWorkGroupSize[i]) {
+         _mesa_glsl_error(&loc, state,
+                          "local_size_%c exceeds MAX_COMPUTE_WORK_GROUP_SIZE"
+                          " (%d)", 'x' + i,
+                          state->ctx->Const.MaxComputeWorkGroupSize[i]);
+         break;
+      }
+      total_invocations *= qual_local_size[i];
+      if (total_invocations >
+          state->ctx->Const.MaxComputeWorkGroupInvocations) {
+         _mesa_glsl_error(&loc, state,
+                          "product of local_sizes exceeds "
+                          "MAX_COMPUTE_WORK_GROUP_INVOCATIONS (%d)",
+                          state->ctx->Const.MaxComputeWorkGroupInvocations);
+         break;
+      }
+   }
+
+   /* If any compute input layout declaration preceded this one, make sure it
+    * was consistent with this one.
+    */
+   if (state->cs_input_local_size_specified) {
+      for (int i = 0; i < 3; i++) {
+         if (state->cs_input_local_size[i] != qual_local_size[i]) {
+            _mesa_glsl_error(&loc, state,
+                             "compute shader input layout does not match"
+                             " previous declaration");
+            return NULL;
+         }
+      }
+   }
+
+   state->cs_input_local_size_specified = true;
+   for (int i = 0; i < 3; i++)
+      state->cs_input_local_size[i] = qual_local_size[i];
+
+   /* We may now declare the built-in constant gl_WorkGroupSize (see
+    * builtin_variable_generator::generate_constants() for why we didn't
+    * declare it earlier).
+    */
+   ir_variable *var = new(state->symbols)
+      ir_variable(glsl_type::uvec3_type, "gl_WorkGroupSize", ir_var_auto);
+   var->data.how_declared = ir_var_declared_implicitly;
+   var->data.read_only = true;
+   instructions->push_tail(var);
+   state->symbols->add_variable(var);
+   ir_constant_data data;
+   memset(&data, 0, sizeof(data));
+   for (int i = 0; i < 3; i++)
+      data.u[i] = qual_local_size[i];
+   var->constant_value = new(var) ir_constant(glsl_type::uvec3_type, &data);
+   var->constant_initializer =
+      new(var) ir_constant(glsl_type::uvec3_type, &data);
+   var->data.has_initializer = true;
+
+   return NULL;
+}
+
+
+static void
+detect_conflicting_assignments(struct _mesa_glsl_parse_state *state,
+                               exec_list *instructions)
+{
+   bool gl_FragColor_assigned = false;
+   bool gl_FragData_assigned = false;
+   bool gl_FragSecondaryColor_assigned = false;
+   bool gl_FragSecondaryData_assigned = false;
+   bool user_defined_fs_output_assigned = false;
+   ir_variable *user_defined_fs_output = NULL;
+
+   /* It would be nice to have proper location information. */
+   YYLTYPE loc;
+   memset(&loc, 0, sizeof(loc));
+
+   foreach_in_list(ir_instruction, node, instructions) {
+      ir_variable *var = node->as_variable();
+
+      if (!var || !var->data.assigned)
+         continue;
+
+      if (strcmp(var->name, "gl_FragColor") == 0)
+         gl_FragColor_assigned = true;
+      else if (strcmp(var->name, "gl_FragData") == 0)
+         gl_FragData_assigned = true;
+	else if (strcmp(var->name, "gl_SecondaryFragColorEXT") == 0)
+         gl_FragSecondaryColor_assigned = true;
+	else if (strcmp(var->name, "gl_SecondaryFragDataEXT") == 0)
+         gl_FragSecondaryData_assigned = true;
+      else if (!is_gl_identifier(var->name)) {
+         if (state->stage == MESA_SHADER_FRAGMENT &&
+             var->data.mode == ir_var_shader_out) {
+            user_defined_fs_output_assigned = true;
+            user_defined_fs_output = var;
+         }
+      }
+   }
+
+   /* From the GLSL 1.30 spec:
+    *
+    *     "If a shader statically assigns a value to gl_FragColor, it
+    *      may not assign a value to any element of gl_FragData. If a
+    *      shader statically writes a value to any element of
+    *      gl_FragData, it may not assign a value to
+    *      gl_FragColor. That is, a shader may assign values to either
+    *      gl_FragColor or gl_FragData, but not both. Multiple shaders
+    *      linked together must also consistently write just one of
+    *      these variables.  Similarly, if user declared output
+    *      variables are in use (statically assigned to), then the
+    *      built-in variables gl_FragColor and gl_FragData may not be
+    *      assigned to. These incorrect usages all generate compile
+    *      time errors."
+    */
+   if (gl_FragColor_assigned && gl_FragData_assigned) {
+      _mesa_glsl_error(&loc, state, "fragment shader writes to both "
+                       "`gl_FragColor' and `gl_FragData'");
+   } else if (gl_FragColor_assigned && user_defined_fs_output_assigned) {
+      _mesa_glsl_error(&loc, state, "fragment shader writes to both "
+                       "`gl_FragColor' and `%s'",
+                       user_defined_fs_output->name);
+   } else if (gl_FragSecondaryColor_assigned && gl_FragSecondaryData_assigned) {
+      _mesa_glsl_error(&loc, state, "fragment shader writes to both "
+                       "`gl_FragSecondaryColorEXT' and"
+                       " `gl_FragSecondaryDataEXT'");
+   } else if (gl_FragColor_assigned && gl_FragSecondaryData_assigned) {
+      _mesa_glsl_error(&loc, state, "fragment shader writes to both "
+                       "`gl_FragColor' and"
+                       " `gl_FragSecondaryDataEXT'");
+   } else if (gl_FragData_assigned && gl_FragSecondaryColor_assigned) {
+      _mesa_glsl_error(&loc, state, "fragment shader writes to both "
+                       "`gl_FragData' and"
+                       " `gl_FragSecondaryColorEXT'");
+   } else if (gl_FragData_assigned && user_defined_fs_output_assigned) {
+      _mesa_glsl_error(&loc, state, "fragment shader writes to both "
+                       "`gl_FragData' and `%s'",
+                       user_defined_fs_output->name);
+   }
+
+   if ((gl_FragSecondaryColor_assigned || gl_FragSecondaryData_assigned) &&
+       !state->EXT_blend_func_extended_enable) {
+      _mesa_glsl_error(&loc, state,
+                       "Dual source blending requires EXT_blend_func_extended");
+   }
+}
+
+
+static void
+remove_per_vertex_blocks(exec_list *instructions,
+                         _mesa_glsl_parse_state *state, ir_variable_mode mode)
+{
+   /* Find the gl_PerVertex interface block of the appropriate (in/out) mode,
+    * if it exists in this shader type.
+    */
+   const glsl_type *per_vertex = NULL;
+   switch (mode) {
+   case ir_var_shader_in:
+      if (ir_variable *gl_in = state->symbols->get_variable("gl_in"))
+         per_vertex = gl_in->get_interface_type();
+      break;
+   case ir_var_shader_out:
+      if (ir_variable *gl_Position =
+          state->symbols->get_variable("gl_Position")) {
+         per_vertex = gl_Position->get_interface_type();
+      }
+      break;
+   default:
+      assert(!"Unexpected mode");
+      break;
+   }
+
+   /* If we didn't find a built-in gl_PerVertex interface block, then we don't
+    * need to do anything.
+    */
+   if (per_vertex == NULL)
+      return;
+
+   /* If the interface block is used by the shader, then we don't need to do
+    * anything.
+    */
+   interface_block_usage_visitor v(mode, per_vertex);
+   v.run(instructions);
+   if (v.usage_found())
+      return;
+
+   /* Remove any ir_variable declarations that refer to the interface block
+    * we're removing.
+    */
+   foreach_in_list_safe(ir_instruction, node, instructions) {
+      ir_variable *const var = node->as_variable();
+      if (var != NULL && var->get_interface_type() == per_vertex &&
+          var->data.mode == mode) {
+         state->symbols->disable_variable(var->name);
+         var->remove();
+      }
+   }
+}