Merge branch 'glsl2-head' into glsl2

This brings in the standalone GLSL compiler that we are planning on
replacing the existing Mesa GLSL compiler.  It currently targets GLSL
1.20 and the Mesa IR.

1 files changed, 2453 insertions, 0 deletions

diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
new file mode 100644
index 00000000000..33eb27533fd
--- /dev/null
+++ b/src/glsl/ast_to_hir.cpp
@@ -0,0 +1,2453 @@
+/*
+ * 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 "main/imports.h"
+#include "glsl_symbol_table.h"
+#include "glsl_parser_extras.h"
+#include "ast.h"
+#include "glsl_types.h"
+#include "ir.h"
+
+void
+_mesa_ast_to_hir(exec_list *instructions, struct _mesa_glsl_parse_state *state)
+{
+   _mesa_glsl_initialize_variables(instructions, state);
+   _mesa_glsl_initialize_constructors(instructions, state);
+   _mesa_glsl_initialize_functions(instructions, state);
+
+   state->current_function = NULL;
+
+   foreach_list_typed (ast_node, ast, link, & state->translation_unit)
+      ast->hir(instructions, state);
+}
+
+
+/**
+ * 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.
+ */
+static bool
+apply_implicit_conversion(const glsl_type *to, ir_rvalue * &from,
+			  struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = talloc_parent(state);
+   if (to->base_type == from->type->base_type)
+      return true;
+
+   /* This conversion was added in GLSL 1.20.  If the compilation mode is
+    * GLSL 1.10, the conversion is skipped.
+    */
+   if (state->language_version < 120)
+      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. There are no implicit conversions between
+    *    signed and unsigned integers."
+    */
+   /* FINISHME: The above comment is partially a lie.  There is int/uint
+    * FINISHME: conversion for immediate constants.
+    */
+   if (!to->is_float() || !from->type->is_numeric())
+      return false;
+
+   switch (from->type->base_type) {
+   case GLSL_TYPE_INT:
+      from = new(ctx) ir_expression(ir_unop_i2f, to, from, NULL);
+      break;
+   case GLSL_TYPE_UINT:
+      from = new(ctx) ir_expression(ir_unop_u2f, to, from, NULL);
+      break;
+   case GLSL_TYPE_BOOL:
+      from = new(ctx) ir_expression(ir_unop_b2f, to, from, NULL);
+      break;
+   default:
+      assert(0);
+   }
+
+   return true;
+}
+
+
+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);
+   assert(type_b->base_type == GLSL_TYPE_FLOAT);
+
+   /*   "* 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 {
+      if (type_a->is_matrix() && type_b->is_matrix()) {
+	 /* Matrix multiply.  The columns of A must match the rows of B.  Given
+	  * the other previously tested constraints, this means the vector type
+	  * of a row from A must be the same as the vector type of a column from
+	  * B.
+	  */
+	 if (type_a->row_type() == type_b->column_type()) {
+	    /* The resulting matrix has the number of columns of matrix B and
+	     * the number of rows of matrix A.  We get the row count of A by
+	     * looking at the size of a vector that makes up a column.  The
+	     * transpose (size of a row) is done for B.
+	     */
+	    const glsl_type *const type =
+	       glsl_type::get_instance(type_a->base_type,
+				       type_a->column_type()->vector_elements,
+				       type_b->row_type()->vector_elements);
+	    assert(type != glsl_type::error_type);
+
+	    return type;
+	 }
+      } else if (type_a->is_matrix()) {
+	 /* A is a matrix and B is a column vector.  Columns of A must match
+	  * rows of B.  Given the other previously tested constraints, this
+	  * means the vector type of a row from A must be the same as the
+	  * vector the type of B.
+	  */
+	 if (type_a->row_type() == type_b)
+	    return type_b;
+      } else {
+	 assert(type_b->is_matrix());
+
+	 /* A is a row vector and B is a matrix.  Columns of A must match rows
+	  * of B.  Given the other previously tested constraints, this means
+	  * the type of A must be the same as the vector type of a column from
+	  * B.
+	  */
+	 if (type_a == type_b->column_type())
+	    return type_a;
+      }
+
+      _mesa_glsl_error(loc, state, "size mismatch for matrix multiplication");
+      return glsl_type::error_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;
+}
+
+
+static const struct glsl_type *
+modulus_result_type(const struct glsl_type *type_a,
+		    const struct glsl_type *type_b,
+		    struct _mesa_glsl_parse_state *state, YYLTYPE *loc)
+{
+   /* From GLSL 1.50 spec, page 56:
+    *    "The operator modulus (%) operates on signed or unsigned integers or
+    *    integer vectors. The operand types must both be signed or both be
+    *    unsigned."
+    */
+   if (!type_a->is_integer() || !type_b->is_integer()
+       || (type_a->base_type != type_b->base_type)) {
+      _mesa_glsl_error(loc, state, "type mismatch");
+      return glsl_type::error_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;
+}
+
+
+/**
+ * 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.
+ */
+ir_rvalue *
+validate_assignment(struct _mesa_glsl_parse_state *state,
+		    const glsl_type *lhs_type, ir_rvalue *rhs)
+{
+   const glsl_type *rhs_type = rhs->type;
+
+   /* 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;
+
+   /* 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 size of the LHS is zero,
+    * the assignment is okay.
+    *
+    * Note: Whole-array assignments are not permitted in GLSL 1.10, but this
+    * is handled by ir_dereference::is_lvalue.
+    */
+   if (lhs_type->is_array() && rhs->type->is_array()
+       && (lhs_type->element_type() == rhs->type->element_type())
+       && (lhs_type->array_size() == 0)) {
+      return rhs;
+   }
+
+   /* Check for implicit conversion in GLSL 1.20 */
+   if (apply_implicit_conversion(lhs_type, rhs, state)) {
+      rhs_type = rhs->type;
+      if (rhs_type == lhs_type)
+	 return rhs;
+   }
+
+   return NULL;
+}
+
+ir_rvalue *
+do_assignment(exec_list *instructions, struct _mesa_glsl_parse_state *state,
+	      ir_rvalue *lhs, ir_rvalue *rhs,
+	      YYLTYPE lhs_loc)
+{
+   void *ctx = talloc_parent(state);
+   bool error_emitted = (lhs->type->is_error() || rhs->type->is_error());
+
+   if (!error_emitted) {
+      /* FINISHME: This does not handle 'foo.bar.a.b.c[5].d = 5' */
+      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->type, rhs);
+   if (new_rhs == NULL) {
+      _mesa_glsl_error(& lhs_loc, state, "type mismatch");
+   } else {
+      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->array_size() == 0) {
+	 ir_dereference *const d = lhs->as_dereference();
+
+	 assert(d != NULL);
+
+	 ir_variable *const var = d->variable_referenced();
+
+	 assert(var != NULL);
+
+	 if (var->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->max_array_access);
+	 }
+
+	 var->type = glsl_type::get_array_instance(state,
+						   lhs->type->element_type(),
+						   rhs->type->array_size());
+      }
+   }
+
+   /* 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;
+    *
+    * So we always just store the computed value being assigned to a
+    * temporary and return a deref of that temporary.  If the rvalue
+    * ends up not being used, the temp will get copy-propagated out.
+    */
+   ir_variable *var = new(ctx) ir_variable(rhs->type, "assignment_tmp");
+   ir_dereference_variable *deref_var = new(ctx) ir_dereference_variable(var);
+   instructions->push_tail(var);
+   instructions->push_tail(new(ctx) ir_assignment(deref_var,
+						  rhs,
+						  NULL));
+   deref_var = new(ctx) ir_dereference_variable(var);
+
+   instructions->push_tail(new(ctx) ir_assignment(lhs,
+						  deref_var,
+						  NULL));
+
+   return new(ctx) ir_dereference_variable(var);
+}
+
+
+/**
+ * Generate a new temporary and add its declaration to the instruction stream
+ */
+static ir_variable *
+generate_temporary(const glsl_type *type, exec_list *instructions,
+		   struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = talloc_parent(state);
+   char *name = (char *) malloc(sizeof(char) * 13);
+
+   snprintf(name, 13, "tmp_%08X", state->temp_index);
+   state->temp_index++;
+
+   ir_variable *const var = new(ctx) ir_variable(type, name);
+   instructions->push_tail(var);
+
+   return var;
+}
+
+
+static ir_rvalue *
+get_lvalue_copy(exec_list *instructions, ir_rvalue *lvalue)
+{
+   void *ctx = talloc_parent(lvalue);
+   ir_variable *var;
+
+   /* FINISHME: Give unique names to the temporaries. */
+   var = new(ctx) ir_variable(lvalue->type, "_post_incdec_tmp");
+   var->mode = ir_var_auto;
+
+   instructions->push_tail(new(ctx) ir_assignment(new(ctx) ir_dereference_variable(var),
+						  lvalue, NULL));
+
+   /* Once we've created this temporary, mark it read only so it's no
+    * longer considered an lvalue.
+    */
+   var->read_only = true;
+
+   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;
+}
+
+
+ir_rvalue *
+ast_expression::hir(exec_list *instructions,
+		    struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = talloc_parent(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_equal,
+      ir_binop_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[2];
+   const struct glsl_type *type = glsl_type::error_type;
+   bool error_emitted = false;
+   YYLTYPE loc;
+
+   loc = this->get_location();
+
+   switch (this->oper) {
+   case ast_assign: {
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+
+      result = do_assignment(instructions, state, op[0], op[1],
+			     this->subexpressions[0]->get_location());
+      error_emitted = result->type->is_error();
+      type = result->type;
+      break;
+   }
+
+   case ast_plus:
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+
+      error_emitted = op[0]->type->is_error();
+      if (type->is_error())
+	 op[0]->type = type;
+
+      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]->type, op[1]->type, 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:
+      _mesa_glsl_error(& loc, state, "FINISHME: implement bit-shift operators");
+      error_emitted = true;
+      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 ((!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 ((state->language_version <= 110)
+		 && (op[0]->type->is_array() || op[1]->type->is_array())) {
+	 _mesa_glsl_error(& loc, state, "array comparisons forbidden in "
+			  "GLSL 1.10");
+	 error_emitted = true;
+      }
+
+      result = new(ctx) ir_expression(operations[this->oper], glsl_type::bool_type,
+				      op[0], op[1]);
+      type = glsl_type::bool_type;
+
+      assert(result->type == glsl_type::bool_type);
+      break;
+
+   case ast_bit_and:
+   case ast_bit_xor:
+   case ast_bit_or:
+   case ast_bit_not:
+      _mesa_glsl_error(& loc, state, "FINISHME: implement bit-wise operators");
+      error_emitted = true;
+      break;
+
+   case ast_logic_and: {
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+
+      if (!op[0]->type->is_boolean() || !op[0]->type->is_scalar()) {
+	 YYLTYPE loc = this->subexpressions[0]->get_location();
+
+	 _mesa_glsl_error(& loc, state, "LHS of `%s' must be scalar boolean",
+			  operator_string(this->oper));
+	 error_emitted = true;
+      }
+
+      ir_constant *op0_const = op[0]->constant_expression_value();
+      if (op0_const) {
+	 if (op0_const->value.b[0]) {
+	    op[1] = this->subexpressions[1]->hir(instructions, state);
+
+	    if (!op[1]->type->is_boolean() || !op[1]->type->is_scalar()) {
+	       YYLTYPE loc = this->subexpressions[1]->get_location();
+
+	       _mesa_glsl_error(& loc, state,
+				"RHS of `%s' must be scalar boolean",
+				operator_string(this->oper));
+	       error_emitted = true;
+	    }
+	    result = op[1];
+	 } else {
+	    result = op0_const;
+	 }
+	 type = glsl_type::bool_type;
+      } else {
+	 ir_if *const stmt = new(ctx) ir_if(op[0]);
+	 instructions->push_tail(stmt);
+
+	 op[1] = this->subexpressions[1]->hir(&stmt->then_instructions, state);
+
+	 if (!op[1]->type->is_boolean() || !op[1]->type->is_scalar()) {
+	    YYLTYPE loc = this->subexpressions[1]->get_location();
+
+	    _mesa_glsl_error(& loc, state,
+			     "RHS of `%s' must be scalar boolean",
+			     operator_string(this->oper));
+	    error_emitted = true;
+	 }
+
+	 ir_variable *const tmp = generate_temporary(glsl_type::bool_type,
+						     instructions, state);
+
+	 ir_dereference *const then_deref = new(ctx) ir_dereference_variable(tmp);
+	 ir_assignment *const then_assign =
+	    new(ctx) ir_assignment(then_deref, op[1], NULL);
+	 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), NULL);
+	 stmt->else_instructions.push_tail(else_assign);
+
+	 result = new(ctx) ir_dereference_variable(tmp);
+	 type = tmp->type;
+      }
+      break;
+   }
+
+   case ast_logic_or: {
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+
+      if (!op[0]->type->is_boolean() || !op[0]->type->is_scalar()) {
+	 YYLTYPE loc = this->subexpressions[0]->get_location();
+
+	 _mesa_glsl_error(& loc, state, "LHS of `%s' must be scalar boolean",
+			  operator_string(this->oper));
+	 error_emitted = true;
+      }
+
+      ir_constant *op0_const = op[0]->constant_expression_value();
+      if (op0_const) {
+	 if (op0_const->value.b[0]) {
+	    result = op0_const;
+	 } else {
+	    op[1] = this->subexpressions[1]->hir(instructions, state);
+
+	    if (!op[1]->type->is_boolean() || !op[1]->type->is_scalar()) {
+	       YYLTYPE loc = this->subexpressions[1]->get_location();
+
+	       _mesa_glsl_error(& loc, state,
+				"RHS of `%s' must be scalar boolean",
+				operator_string(this->oper));
+	       error_emitted = true;
+	    }
+	    result = op[1];
+	 }
+	 type = glsl_type::bool_type;
+      } else {
+	 ir_if *const stmt = new(ctx) ir_if(op[0]);
+	 instructions->push_tail(stmt);
+
+	 ir_variable *const tmp = generate_temporary(glsl_type::bool_type,
+						     instructions, state);
+
+	 op[1] = this->subexpressions[1]->hir(&stmt->then_instructions, state);
+
+	 if (!op[1]->type->is_boolean() || !op[1]->type->is_scalar()) {
+	    YYLTYPE loc = this->subexpressions[1]->get_location();
+
+	    _mesa_glsl_error(& loc, state, "RHS of `%s' must be scalar boolean",
+			     operator_string(this->oper));
+	    error_emitted = true;
+	 }
+
+	 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), NULL);
+	 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, op[1], NULL);
+	 stmt->else_instructions.push_tail(else_assign);
+
+	 result = new(ctx) ir_dereference_variable(tmp);
+	 type = tmp->type;
+      }
+      break;
+   }
+
+   case ast_logic_xor:
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      op[1] = this->subexpressions[1]->hir(instructions, state);
+
+
+      result = new(ctx) ir_expression(operations[this->oper], glsl_type::bool_type,
+				      op[0], op[1]);
+      type = glsl_type::bool_type;
+      break;
+
+   case ast_logic_not:
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+
+      if (!op[0]->type->is_boolean() || !op[0]->type->is_scalar()) {
+	 YYLTYPE loc = this->subexpressions[0]->get_location();
+
+	 _mesa_glsl_error(& loc, state,
+			  "operand of `!' must be scalar boolean");
+	 error_emitted = true;
+      }
+
+      result = new(ctx) ir_expression(operations[this->oper], glsl_type::bool_type,
+				      op[0], NULL);
+      type = glsl_type::bool_type;
+      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]);
+
+      result = do_assignment(instructions, state,
+			     (ir_rvalue *)op[0]->clone(NULL), temp_rhs,
+			     this->subexpressions[0]->get_location());
+      type = result->type;
+      error_emitted = (op[0]->type->is_error());
+
+      /* 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]->type, op[1]->type, state, & loc);
+
+      assert(operations[this->oper] == ir_binop_mod);
+
+      struct ir_rvalue *temp_rhs;
+      temp_rhs = new(ctx) ir_expression(operations[this->oper], type,
+					op[0], op[1]);
+
+      result = do_assignment(instructions, state,
+			     (ir_rvalue *)op[0]->clone(NULL), temp_rhs,
+			     this->subexpressions[0]->get_location());
+      type = result->type;
+      error_emitted = type->is_error();
+      break;
+   }
+
+   case ast_ls_assign:
+   case ast_rs_assign:
+      _mesa_glsl_error(& loc, state,
+		       "FINISHME: implement bit-shift assignment operators");
+      error_emitted = true;
+      break;
+
+   case ast_and_assign:
+   case ast_xor_assign:
+   case ast_or_assign:
+      _mesa_glsl_error(& loc, state,
+		       "FINISHME: implement logic assignment operators");
+      error_emitted = true;
+      break;
+
+   case ast_conditional: {
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+
+      /* 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."
+       */
+      if (!op[0]->type->is_boolean() || !op[0]->type->is_scalar()) {
+	 YYLTYPE loc = this->subexpressions[0]->get_location();
+
+	 _mesa_glsl_error(& loc, state, "?: condition must be scalar boolean");
+	 error_emitted = true;
+      }
+
+      /* 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;
+      }
+
+      ir_constant *cond_val = op[0]->constant_expression_value();
+      ir_constant *then_val = op[1]->constant_expression_value();
+      ir_constant *else_val = op[2]->constant_expression_value();
+
+      if (then_instructions.is_empty()
+	  && else_instructions.is_empty()
+	  && (cond_val != NULL) && (then_val != NULL) && (else_val != NULL)) {
+	 result = (cond_val->value.b[0]) ? then_val : else_val;
+      } else {
+	 ir_variable *const tmp = generate_temporary(type,
+						     instructions, state);
+
+	 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], NULL);
+	 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], NULL);
+	 stmt->else_instructions.push_tail(else_assign);
+
+	 result = new(ctx) ir_dereference_variable(tmp);
+      }
+      break;
+   }
+
+   case ast_pre_inc:
+   case ast_pre_dec: {
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      if (op[0]->type->base_type == GLSL_TYPE_FLOAT)
+	 op[1] = new(ctx) ir_constant(1.0f);
+      else
+	 op[1] = new(ctx) ir_constant(1);
+
+      type = arithmetic_result_type(op[0], op[1], false, state, & loc);
+
+      struct ir_rvalue *temp_rhs;
+      temp_rhs = new(ctx) ir_expression(operations[this->oper], type,
+					op[0], op[1]);
+
+      result = do_assignment(instructions, state,
+			     (ir_rvalue *)op[0]->clone(NULL), temp_rhs,
+			     this->subexpressions[0]->get_location());
+      type = result->type;
+      error_emitted = op[0]->type->is_error();
+      break;
+   }
+
+   case ast_post_inc:
+   case ast_post_dec: {
+      op[0] = this->subexpressions[0]->hir(instructions, state);
+      if (op[0]->type->base_type == GLSL_TYPE_FLOAT)
+	 op[1] = new(ctx) ir_constant(1.0f);
+      else
+	 op[1] = new(ctx) ir_constant(1);
+
+      error_emitted = op[0]->type->is_error() || op[1]->type->is_error();
+
+      type = arithmetic_result_type(op[0], op[1], false, state, & loc);
+
+      struct 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, (ir_rvalue *)op[0]->clone(NULL));
+
+      (void)do_assignment(instructions, state,
+			  (ir_rvalue *)op[0]->clone(NULL), temp_rhs,
+			  this->subexpressions[0]->get_location());
+
+      type = result->type;
+      error_emitted = op[0]->type->is_error();
+      break;
+   }
+
+   case ast_field_selection:
+      result = _mesa_ast_field_selection_to_hir(this, instructions, state);
+      type = result->type;
+      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);
+
+      error_emitted = op[0]->type->is_error() || op[1]->type->is_error();
+
+      ir_rvalue *const array = op[0];
+
+      result = new(ctx) ir_dereference_array(op[0], op[1]);
+
+      /* Do not use op[0] after this point.  Use array.
+       */
+      op[0] = NULL;
+
+
+      if (error_emitted)
+	 break;
+
+      if (!array->type->is_array()
+	  && !array->type->is_matrix()
+	  && !array->type->is_vector()) {
+	 _mesa_glsl_error(& index_loc, state,
+			  "cannot dereference non-array / non-matrix / "
+			  "non-vector");
+	 error_emitted = true;
+      }
+
+      if (!op[1]->type->is_integer()) {
+	 _mesa_glsl_error(& index_loc, state,
+			  "array index must be integer type");
+	 error_emitted = true;
+      } else if (!op[1]->type->is_scalar()) {
+	 _mesa_glsl_error(& index_loc, state,
+			  "array index must be scalar");
+	 error_emitted = true;
+      }
+
+      /* If the array index is a constant expression and the array has a
+       * declared size, ensure that the access is in-bounds.  If the array
+       * index is not a constant expression, ensure that the array has a
+       * declared size.
+       */
+      ir_constant *const const_index = op[1]->constant_expression_value();
+      if (const_index != NULL) {
+	 const int idx = const_index->value.i[0];
+	 const char *type_name;
+	 unsigned bound = 0;
+
+	 if (array->type->is_matrix()) {
+	    type_name = "matrix";
+	 } else if (array->type->is_vector()) {
+	    type_name = "vector";
+	 } else {
+	    type_name = "array";
+	 }
+
+	 /* From page 24 (page 30 of the PDF) of the GLSL 1.50 spec:
+	  *
+	  *    "It is illegal to declare an array with a size, and then
+	  *    later (in the same shader) index the same array with an
+	  *    integral constant expression greater than or equal to the
+	  *    declared size. It is also illegal to index an array with a
+	  *    negative constant expression."
+	  */
+	 if (array->type->is_matrix()) {
+	    if (array->type->row_type()->vector_elements <= idx) {
+	       bound = array->type->row_type()->vector_elements;
+	    }
+	 } else if (array->type->is_vector()) {
+	    if (array->type->vector_elements <= idx) {
+	       bound = array->type->vector_elements;
+	    }
+	 } else {
+	    if ((array->type->array_size() > 0)
+		&& (array->type->array_size() <= idx)) {
+	       bound = array->type->array_size();
+	    }
+	 }
+
+	 if (bound > 0) {
+	    _mesa_glsl_error(& loc, state, "%s index must be < %u",
+			     type_name, bound);
+	    error_emitted = true;
+	 } else if (idx < 0) {
+	    _mesa_glsl_error(& loc, state, "%s index must be >= 0",
+			     type_name);
+	    error_emitted = true;
+	 }
+
+	 if (array->type->is_array()) {
+	    /* If the array is a variable dereference, it dereferences the
+	     * whole array, by definition.  Use this to get the variable.
+	     *
+	     * FINISHME: Should some methods for getting / setting / testing
+	     * FINISHME: array access limits be added to ir_dereference?
+	     */
+	    ir_variable *const v = array->whole_variable_referenced();
+	    if ((v != NULL) && (unsigned(idx) > v->max_array_access))
+	       v->max_array_access = idx;
+	 }
+      }
+
+      if (error_emitted)
+	 result->type = glsl_type::error_type;
+
+      type = result->type;
+      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);
+
+      result = new(ctx) ir_dereference_variable(var);
+
+      if (var != NULL) {
+	 type = result->type;
+      } else {
+	 _mesa_glsl_error(& loc, state, "`%s' undeclared",
+			  this->primary_expression.identifier);
+
+	 error_emitted = true;
+      }
+      break;
+   }
+
+   case ast_int_constant:
+      type = glsl_type::int_type;
+      result = new(ctx) ir_constant(this->primary_expression.int_constant);
+      break;
+
+   case ast_uint_constant:
+      type = glsl_type::uint_type;
+      result = new(ctx) ir_constant(this->primary_expression.uint_constant);
+      break;
+
+   case ast_float_constant:
+      type = glsl_type::float_type;
+      result = new(ctx) ir_constant(this->primary_expression.float_constant);
+      break;
+
+   case ast_bool_constant:
+      type = glsl_type::bool_type;
+      result = new(ctx) ir_constant(bool(this->primary_expression.bool_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.
+       */
+      foreach_list_typed (ast_node, ast, link, &this->expressions)
+	 result = ast->hir(instructions, state);
+
+      type = result->type;
+
+      /* Any errors should have already been emitted in the loop above.
+       */
+      error_emitted = true;
+      break;
+   }
+   }
+
+   if (type->is_error() && !error_emitted)
+      _mesa_glsl_error(& loc, state, "type mismatch");
+
+   return result;
+}
+
+
+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(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;
+}
+
+
+static const glsl_type *
+process_array_type(const glsl_type *base, ast_node *array_size,
+		   struct _mesa_glsl_parse_state *state)
+{
+   unsigned length = 0;
+
+   /* FINISHME: Reject delcarations of multidimensional arrays. */
+
+   if (array_size != NULL) {
+      exec_list dummy_instructions;
+      ir_rvalue *const ir = array_size->hir(& dummy_instructions, state);
+      YYLTYPE loc = array_size->get_location();
+
+      /* FINISHME: Verify that the grammar forbids side-effects in array
+       * FINISHME: sizes.   i.e., 'vec4 [x = 12] data'
+       */
+      assert(dummy_instructions.is_empty());
+
+      if (ir != NULL) {
+	 if (!ir->type->is_integer()) {
+	    _mesa_glsl_error(& loc, state, "array size must be integer type");
+	 } else if (!ir->type->is_scalar()) {
+	    _mesa_glsl_error(& loc, state, "array size must be scalar type");
+	 } else {
+	    ir_constant *const size = ir->constant_expression_value();
+
+	    if (size == NULL) {
+	       _mesa_glsl_error(& loc, state, "array size must be a "
+				"constant valued expression");
+	    } else if (size->value.i[0] <= 0) {
+	       _mesa_glsl_error(& loc, state, "array size must be > 0");
+	    } else {
+	       assert(size->type == ir->type);
+	       length = size->value.u[0];
+	    }
+	 }
+      }
+   }
+
+   return glsl_type::get_array_instance(state, base, length);
+}
+
+
+const glsl_type *
+ast_type_specifier::glsl_type(const char **name,
+			      struct _mesa_glsl_parse_state *state) const
+{
+   const struct glsl_type *type;
+
+   if ((this->type_specifier == ast_struct) && (this->type_name == NULL)) {
+      /* FINISHME: Handle annonymous structures. */
+      type = NULL;
+   } else {
+      type = state->symbols->get_type(this->type_name);
+      *name = this->type_name;
+
+      if (this->is_array) {
+	 type = process_array_type(type, this->array_size, state);
+      }
+   }
+
+   return type;
+}
+
+
+static void
+apply_type_qualifier_to_variable(const struct ast_type_qualifier *qual,
+				 struct ir_variable *var,
+				 struct _mesa_glsl_parse_state *state,
+				 YYLTYPE *loc)
+{
+   if (qual->invariant)
+      var->invariant = 1;
+
+   /* FINISHME: Mark 'in' variables at global scope as read-only. */
+   if (qual->constant || qual->attribute || qual->uniform
+       || (qual->varying && (state->target == fragment_shader)))
+      var->read_only = 1;
+
+   if (qual->centroid)
+      var->centroid = 1;
+
+   if (qual->attribute && state->target != vertex_shader) {
+      var->type = glsl_type::error_type;
+      _mesa_glsl_error(loc, state,
+		       "`attribute' variables may not be declared in the "
+		       "%s shader",
+		       _mesa_glsl_shader_target_name(state->target));
+   }
+
+   /* 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."
+    */
+   if (qual->varying) {
+      const glsl_type *non_array_type;
+
+      if (var->type && var->type->is_array())
+	 non_array_type = var->type->fields.array;
+      else
+	 non_array_type = var->type;
+
+      if (non_array_type && non_array_type->base_type != GLSL_TYPE_FLOAT) {
+	 var->type = glsl_type::error_type;
+	 _mesa_glsl_error(loc, state,
+			  "varying variables must be of base type float");
+      }
+   }
+
+   if (qual->in && qual->out)
+      var->mode = ir_var_inout;
+   else if (qual->attribute || qual->in
+	    || (qual->varying && (state->target == fragment_shader)))
+      var->mode = ir_var_in;
+   else if (qual->out || (qual->varying && (state->target == vertex_shader)))
+      var->mode = ir_var_out;
+   else if (qual->uniform)
+      var->mode = ir_var_uniform;
+   else
+      var->mode = ir_var_auto;
+
+   if (qual->uniform)
+      var->shader_in = true;
+
+   /* Any 'in' or 'inout' variables at global scope must be marked as being
+    * shader inputs.  Likewise, any 'out' or 'inout' variables at global scope
+    * must be marked as being shader outputs.
+    */
+   if (state->current_function == NULL) {
+      switch (var->mode) {
+      case ir_var_in:
+      case ir_var_uniform:
+	 var->shader_in = true;
+	 break;
+      case ir_var_out:
+	 var->shader_out = true;
+	 break;
+      case ir_var_inout:
+	 var->shader_in = true;
+	 var->shader_out = true;
+	 break;
+      default:
+	 break;
+      }
+   }
+
+   if (qual->flat)
+      var->interpolation = ir_var_flat;
+   else if (qual->noperspective)
+      var->interpolation = ir_var_noperspective;
+   else
+      var->interpolation = ir_var_smooth;
+
+   if (var->type->is_array() && (state->language_version >= 120)) {
+      var->array_lvalue = true;
+   }
+}
+
+
+ir_rvalue *
+ast_declarator_list::hir(exec_list *instructions,
+			 struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = talloc_parent(state);
+   const struct glsl_type *decl_type;
+   const char *type_name = NULL;
+   ir_rvalue *result = NULL;
+   YYLTYPE loc = this->get_location();
+
+   /* The type specifier may contain a structure definition.  Process that
+    * before any of the variable declarations.
+    */
+   (void) this->type->specifier->hir(instructions, state);
+
+   /* FINISHME: Handle vertex shader "invariant" declarations that do not
+    * FINISHME: include a type.  These re-declare built-in variables to be
+    * FINISHME: invariant.
+    */
+
+   decl_type = this->type->specifier->glsl_type(& type_name, state);
+   if (this->declarations.is_empty()) {
+      /* There are only two valid cases where the declaration list can be
+       * empty.
+       *
+       * 1. The declaration is setting the default precision of a built-in
+       *    type (e.g., 'precision highp vec4;').
+       *
+       * 2. Adding 'invariant' to an existing vertex shader output.
+       */
+
+      if (this->type->qualifier.invariant) {
+      } else if (decl_type != NULL) {
+      } else {
+	    _mesa_glsl_error(& loc, state, "incomplete declaration");
+      }
+   }
+
+   foreach_list_typed (ast_declaration, decl, link, &this->declarations) {
+      const struct glsl_type *var_type;
+      struct ir_variable *var;
+
+      /* 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 (decl->is_array) {
+	 var_type = process_array_type(decl_type, decl->array_size, state);
+      } else {
+	 var_type = decl_type;
+      }
+
+      var = new(ctx) ir_variable(var_type, 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, uni form, or varying. Only one may be
+       *     specified.
+       *
+       *     Local variables can only use the qualifier const."
+       *
+       * This is relaxed in GLSL 1.30.
+       */
+      if (state->language_version < 120) {
+	 if (this->type->qualifier.out) {
+	    _mesa_glsl_error(& loc, state,
+			     "`out' qualifier in declaration of `%s' "
+			     "only valid for function parameters in GLSL 1.10.",
+			     decl->identifier);
+	 }
+	 if (this->type->qualifier.in) {
+	    _mesa_glsl_error(& loc, state,
+			     "`in' qualifier in declaration of `%s' "
+			     "only valid for function parameters in GLSL 1.10.",
+			     decl->identifier);
+	 }
+	 /* FINISHME: Test for other invalid qualifiers. */
+      }
+
+      apply_type_qualifier_to_variable(& this->type->qualifier, var, state,
+				       & loc);
+
+      /* Attempt to add the variable to the symbol table.  If this fails, it
+       * means the variable has already been declared at this scope.  Arrays
+       * fudge this rule a little bit.
+       *
+       * 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 (state->symbols->name_declared_this_scope(decl->identifier)) {
+	 ir_variable *const earlier =
+	    state->symbols->get_variable(decl->identifier);
+
+	 if ((earlier != NULL)
+	     && (earlier->type->array_size() == 0)
+	     && var->type->is_array()
+	     && (var->type->element_type() == earlier->type->element_type())) {
+	    /* FINISHME: This doesn't match the qualifiers on the two
+	     * FINISHME: declarations.  It's not 100% clear whether this is
+	     * FINISHME: required or not.
+	     */
+
+	    if (var->type->array_size() <= (int)earlier->max_array_access) {
+	       YYLTYPE loc = this->get_location();
+
+	       _mesa_glsl_error(& loc, state, "array size must be > %u due to "
+				"previous access",
+				earlier->max_array_access);
+	    }
+
+	    earlier->type = var->type;
+	    delete var;
+	    var = NULL;
+	 } else {
+	    YYLTYPE loc = this->get_location();
+
+	    _mesa_glsl_error(& loc, state, "`%s' redeclared",
+			     decl->identifier);
+	 }
+
+	 continue;
+      }
+
+      /* 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 (strncmp(decl->identifier, "gl_", 3) == 0) {
+	 /* FINISHME: This should only trigger if we're not redefining
+	  * FINISHME: a builtin (to add a qualifier, for example).
+	  */
+	 _mesa_glsl_error(& loc, state,
+			  "identifier `%s' uses reserved `gl_' prefix",
+			  decl->identifier);
+      }
+
+      instructions->push_tail(var);
+
+      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.attribute) {
+	    mode = "attribute";
+	 } else if (this->type->qualifier.uniform) {
+	    mode = "uniform";
+	 } else if (this->type->qualifier.varying) {
+	    mode = "varying";
+	 } else if (this->type->qualifier.in) {
+	    mode = "in";
+	    extra = " or in function parameter list";
+	 } else if (this->type->qualifier.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->mode == ir_var_in) {
+	 if (state->target == vertex_shader) {
+	    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."
+	     */
+	    const glsl_type *check_type = var->type->is_array()
+	       ? var->type->fields.array : var->type;
+
+	    switch (check_type->base_type) {
+	    case GLSL_TYPE_FLOAT:
+	       break;
+	    case GLSL_TYPE_UINT:
+	    case GLSL_TYPE_INT:
+	       if (state->language_version > 120)
+		  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 && (state->language_version <= 130)
+		&& var->type->is_array()) {
+	       _mesa_glsl_error(& loc, state,
+				"vertex shader input / attribute cannot have "
+				"array type");
+	       error_emitted = true;
+	    }
+	 }
+      }
+
+      if (decl->initializer != 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 ((state->language_version <= 110)
+	     && (var->mode == ir_var_uniform)) {
+	    _mesa_glsl_error(& initializer_loc, state,
+			     "cannot initialize uniforms in GLSL 1.10");
+	 }
+
+	 if (var->type->is_sampler()) {
+	    _mesa_glsl_error(& initializer_loc, state,
+			     "cannot initialize samplers");
+	 }
+
+	 if ((var->mode == ir_var_in) && (state->current_function == NULL)) {
+	    _mesa_glsl_error(& initializer_loc, state,
+			     "cannot initialize %s shader input / %s",
+			     _mesa_glsl_shader_target_name(state->target),
+			     (state->target == vertex_shader)
+			     ? "attribute" : "varying");
+	 }
+
+	 ir_dereference *const lhs = new(ctx) ir_dereference_variable(var);
+	 ir_rvalue *rhs = decl->initializer->hir(instructions, state);
+
+	 /* Calculate the constant value if this is a const or uniform
+	  * declaration.
+	  */
+	 if (this->type->qualifier.constant || this->type->qualifier.uniform) {
+	    ir_constant *constant_value = rhs->constant_expression_value();
+	    if (!constant_value) {
+	       _mesa_glsl_error(& initializer_loc, state,
+				"initializer of %s variable `%s' must be a "
+				"constant expression",
+				(this->type->qualifier.constant)
+				? "const" : "uniform",
+				decl->identifier);
+	    } else {
+	       rhs = constant_value;
+	       var->constant_value = constant_value;
+	    }
+	 }
+
+	 if (rhs && !rhs->type->is_error()) {
+	    bool temp = var->read_only;
+	    if (this->type->qualifier.constant)
+	       var->read_only = false;
+
+	    /* Never emit code to initialize a uniform.
+	     */
+	    if (!this->type->qualifier.uniform)
+	       result = do_assignment(instructions, state, lhs, rhs,
+				      this->get_location());
+	    var->read_only = temp;
+	 }
+      }
+
+      /* 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.constant && decl->initializer == NULL) {
+	 _mesa_glsl_error(& loc, state,
+			  "const declaration of `%s' must be initialized");
+      }
+
+      /* Add the vairable to the symbol table after processing the initializer.
+       * 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."
+       */
+      const bool added_variable =
+	 state->symbols->add_variable(decl->identifier, var);
+      assert(added_variable);
+   }
+
+
+   /* 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 = talloc_parent(state);
+   const struct glsl_type *type;
+   const char *name = NULL;
+   YYLTYPE loc = this->get_location();
+
+   type = this->type->specifier->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;
+   }
+
+   is_void = false;
+   ir_variable *var = new(ctx) ir_variable(type, this->identifier);
+
+   /* FINISHME: Handle array declarations.  Note that this requires
+    * FINISHME: complete handling of constant expressions.
+    */
+
+   /* 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);
+   if (var->mode == ir_var_auto)
+      var->mode = ir_var_in;
+
+   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");
+   }
+}
+
+
+ir_rvalue *
+ast_function::hir(exec_list *instructions,
+		  struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = talloc_parent(state);
+   ir_function *f = NULL;
+   ir_function_signature *sig = NULL;
+   exec_list hir_parameters;
+
+
+   /* 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->specifier->glsl_type(& return_type_name, state);
+
+   assert(return_type != 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.
+    */
+   const char *const name = identifier;
+   f = state->symbols->get_function(name);
+   if (f != NULL) {
+      ir_function_signature *sig = f->exact_matching_signature(&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 (is_definition && sig->is_defined) {
+	    YYLTYPE loc = this->get_location();
+
+	    _mesa_glsl_error(& loc, state, "function `%s' redefined", name);
+	    sig = NULL;
+	 }
+      }
+   } else if (state->symbols->name_declared_this_scope(name)) {
+      /* 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);
+      sig = NULL;
+   } else {
+      f = new(ctx) ir_function(name);
+      state->symbols->add_function(f->name, f);
+
+      /* Emit the new function header */
+      instructions->push_tail(f);
+   }
+
+   /* 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;
+
+   /* 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;
+
+   assert(state->current_function == NULL);
+   state->current_function = signature;
+
+   /* Duplicate parameters declared in the prototype as concrete variables.
+    * Add these to the symbol table.
+    */
+   state->symbols->push_scope();
+   foreach_iter(exec_list_iterator, iter, signature->parameters) {
+      ir_variable *const var = ((ir_instruction *) iter.get())->as_variable();
+
+      assert(var != 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->name, 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;
+
+   /* 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 = talloc_parent(state);
+
+   switch (mode) {
+   case ast_return: {
+      ir_return *inst;
+      assert(state->current_function);
+
+      if (opt_return_value) {
+	 if (state->current_function->return_type->base_type ==
+	     GLSL_TYPE_VOID) {
+	    YYLTYPE loc = this->get_location();
+
+	    _mesa_glsl_error(& loc, state,
+			     "`return` with a value, in function `%s' "
+			     "returning void",
+			     state->current_function->function_name());
+	 }
+
+	 ir_expression *const ret = (ir_expression *)
+	    opt_return_value->hir(instructions, state);
+	 assert(ret != NULL);
+
+	 /* FINISHME: Make sure the type of the return value matches the return
+	  * FINISHME: type of the enclosing function.
+	  */
+
+	 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;
+      }
+
+      instructions->push_tail(inst);
+      break;
+   }
+
+   case ast_discard:
+      /* FINISHME: discard support */
+      if (state->target != fragment_shader) {
+	 YYLTYPE loc = this->get_location();
+
+	 _mesa_glsl_error(& loc, state,
+			  "`discard' may only appear in a fragment shader");
+      }
+      break;
+
+   case ast_break:
+   case ast_continue:
+      /* FINISHME: Handle switch-statements.  They cannot contain 'continue',
+       * FINISHME: and they use a different IR instruction for 'break'.
+       */
+      /* FINISHME: Correctly handle the nesting.  If a switch-statement is
+       * FINISHME: inside a loop, a 'continue' is valid and will bind to the
+       * FINISHME: loop.
+       */
+      if (state->loop_or_switch_nesting == NULL) {
+	 YYLTYPE loc = this->get_location();
+
+	 _mesa_glsl_error(& loc, state,
+			  "`%s' may only appear in a loop",
+			  (mode == ast_break) ? "break" : "continue");
+      } else {
+	 ir_loop *const loop = state->loop_or_switch_nesting->as_loop();
+
+	 if (loop != NULL) {
+	    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 = talloc_parent(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)
+      then_statement->hir(& stmt->then_instructions, state);
+
+   if (else_statement != NULL)
+      else_statement->hir(& stmt->else_instructions, state);
+
+   instructions->push_tail(stmt);
+
+   /* if-statements do not have r-values.
+    */
+   return NULL;
+}
+
+
+void
+ast_iteration_statement::condition_to_hir(ir_loop *stmt,
+					  struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = talloc_parent(state);
+
+   if (condition != NULL) {
+      ir_rvalue *const cond =
+	 condition->hir(& stmt->body_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, glsl_type::bool_type, cond,
+				   NULL);
+
+	 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);
+	 stmt->body_instructions.push_tail(if_stmt);
+      }
+   }
+}
+
+
+ir_rvalue *
+ast_iteration_statement::hir(exec_list *instructions,
+			     struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = talloc_parent(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 and / or switch-statement nesting.
+    */
+   ir_instruction *const nesting = state->loop_or_switch_nesting;
+   state->loop_or_switch_nesting = stmt;
+
+   if (mode != ast_do_while)
+      condition_to_hir(stmt, 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, state);
+
+   if (mode != ast_do_while)
+      state->symbols->pop_scope();
+
+   /* Restore previous nesting before returning.
+    */
+   state->loop_or_switch_nesting = nesting;
+
+   /* Loops do not have r-values.
+    */
+   return NULL;
+}
+
+
+ir_rvalue *
+ast_type_specifier::hir(exec_list *instructions,
+			  struct _mesa_glsl_parse_state *state)
+{
+   if (this->structure != NULL)
+      return this->structure->hir(instructions, state);
+
+   return NULL;
+}
+
+
+ir_rvalue *
+ast_struct_specifier::hir(exec_list *instructions,
+			  struct _mesa_glsl_parse_state *state)
+{
+   void *ctx = talloc_parent(state);
+   unsigned decl_count = 0;
+
+   /* Make an initial pass over the list of structure 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,
+		       &this->declarations) {
+      foreach_list_const (decl_ptr, & decl_list->declarations) {
+	 decl_count++;
+      }
+   }
+
+
+   /* Allocate storage for the structure 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 are processed.
+    */
+   glsl_struct_field *const fields = (glsl_struct_field *)
+      malloc(sizeof(*fields) * decl_count);
+
+   unsigned i = 0;
+   foreach_list_typed (ast_declarator_list, decl_list, link,
+		       &this->declarations) {
+      const char *type_name;
+
+      decl_list->type->specifier->hir(instructions, state);
+
+      const glsl_type *decl_type =
+	 decl_list->type->specifier->glsl_type(& type_name, state);
+
+      foreach_list_typed (ast_declaration, decl, link,
+			  &decl_list->declarations) {
+	 const struct glsl_type *const field_type =
+	    (decl->is_array)
+	    ? process_array_type(decl_type, decl->array_size, state)
+	    : decl_type;
+
+	 fields[i].type = (field_type != NULL)
+	    ? field_type : glsl_type::error_type;
+	 fields[i].name = decl->identifier;
+	 i++;
+      }
+   }
+
+   assert(i == decl_count);
+
+   const char *name;
+   if (this->name == NULL) {
+      static unsigned anon_count = 1;
+      char buf[32];
+
+      snprintf(buf, sizeof(buf), "#anon_struct_%04x", anon_count);
+      anon_count++;
+
+      name = strdup(buf);
+   } else {
+      name = this->name;
+   }
+
+   glsl_type *t = new(ctx) glsl_type(fields, decl_count, name);
+
+   YYLTYPE loc = this->get_location();
+   if (!state->symbols->add_type(name, t)) {
+      _mesa_glsl_error(& loc, state, "struct `%s' previously defined", name);
+   } else {
+      /* This logic is a bit tricky.  It is an error to declare a structure at
+       * global scope if there is also a function with the same name.
+       */
+      if ((state->current_function == NULL)
+	  && (state->symbols->get_function(name) != NULL)) {
+	 _mesa_glsl_error(& loc, state, "name `%s' previously defined", name);
+      } else {
+	 t->generate_constructor(state->symbols);
+      }
+
+      const glsl_type **s = (const glsl_type **)
+	 realloc(state->user_structures,
+		 sizeof(state->user_structures[0]) *
+		 (state->num_user_structures + 1));
+      if (s != NULL) {
+	 s[state->num_user_structures] = t;
+	 state->user_structures = s;
+	 state->num_user_structures++;
+      }
+   }
+
+   /* Structure type definitions do not have r-values.
+    */
+   return NULL;
+}