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, 252 insertions, 0 deletions

diff --git a/src/compiler/glsl/lower_if_to_cond_assign.cpp b/src/compiler/glsl/lower_if_to_cond_assign.cpp
new file mode 100644
index 00000000000..6a7034794b2
--- /dev/null
+++ b/src/compiler/glsl/lower_if_to_cond_assign.cpp
@@ -0,0 +1,252 @@
+/*
+ * 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 lower_if_to_cond_assign.cpp
+ *
+ * This attempts to flatten if-statements to conditional assignments for
+ * GPUs with limited or no flow control support.
+ *
+ * It can't handle other control flow being inside of its block, such
+ * as calls or loops.  Hopefully loop unrolling and inlining will take
+ * care of those.
+ *
+ * Drivers for GPUs with no control flow support should simply call
+ *
+ *    lower_if_to_cond_assign(instructions)
+ *
+ * to attempt to flatten all if-statements.
+ *
+ * Some GPUs (such as i965 prior to gen6) do support control flow, but have a
+ * maximum nesting depth N.  Drivers for such hardware can call
+ *
+ *    lower_if_to_cond_assign(instructions, N)
+ *
+ * to attempt to flatten any if-statements appearing at depth > N.
+ */
+
+#include "compiler/glsl_types.h"
+#include "ir.h"
+#include "program/hash_table.h"
+
+namespace {
+
+class ir_if_to_cond_assign_visitor : public ir_hierarchical_visitor {
+public:
+   ir_if_to_cond_assign_visitor(unsigned max_depth)
+   {
+      this->progress = false;
+      this->max_depth = max_depth;
+      this->depth = 0;
+
+      this->condition_variables = hash_table_ctor(0, hash_table_pointer_hash,
+						  hash_table_pointer_compare);
+   }
+
+   ~ir_if_to_cond_assign_visitor()
+   {
+      hash_table_dtor(this->condition_variables);
+   }
+
+   ir_visitor_status visit_enter(ir_if *);
+   ir_visitor_status visit_leave(ir_if *);
+
+   bool progress;
+   unsigned max_depth;
+   unsigned depth;
+
+   struct hash_table *condition_variables;
+};
+
+} /* anonymous namespace */
+
+bool
+lower_if_to_cond_assign(exec_list *instructions, unsigned max_depth)
+{
+   if (max_depth == UINT_MAX)
+      return false;
+
+   ir_if_to_cond_assign_visitor v(max_depth);
+
+   visit_list_elements(&v, instructions);
+
+   return v.progress;
+}
+
+void
+check_control_flow(ir_instruction *ir, void *data)
+{
+   bool *found_control_flow = (bool *)data;
+   switch (ir->ir_type) {
+   case ir_type_call:
+   case ir_type_discard:
+   case ir_type_loop:
+   case ir_type_loop_jump:
+   case ir_type_return:
+      *found_control_flow = true;
+      break;
+   default:
+      break;
+   }
+}
+
+void
+move_block_to_cond_assign(void *mem_ctx,
+			  ir_if *if_ir, ir_rvalue *cond_expr,
+			  exec_list *instructions,
+			  struct hash_table *ht)
+{
+   foreach_in_list_safe(ir_instruction, ir, instructions) {
+      if (ir->ir_type == ir_type_assignment) {
+	 ir_assignment *assign = (ir_assignment *)ir;
+
+	 if (hash_table_find(ht, assign) == NULL) {
+	    hash_table_insert(ht, assign, assign);
+
+	    /* If the LHS of the assignment is a condition variable that was
+	     * previously added, insert an additional assignment of false to
+	     * the variable.
+	     */
+	    const bool assign_to_cv =
+	       hash_table_find(ht, assign->lhs->variable_referenced()) != NULL;
+
+	    if (!assign->condition) {
+	       if (assign_to_cv) {
+		  assign->rhs =
+		     new(mem_ctx) ir_expression(ir_binop_logic_and,
+						glsl_type::bool_type,
+						cond_expr->clone(mem_ctx, NULL),
+						assign->rhs);
+	       } else {
+		  assign->condition = cond_expr->clone(mem_ctx, NULL);
+	       }
+	    } else {
+	       assign->condition =
+		  new(mem_ctx) ir_expression(ir_binop_logic_and,
+					     glsl_type::bool_type,
+					     cond_expr->clone(mem_ctx, NULL),
+					     assign->condition);
+	    }
+	 }
+      }
+
+      /* Now, move from the if block to the block surrounding it. */
+      ir->remove();
+      if_ir->insert_before(ir);
+   }
+}
+
+ir_visitor_status
+ir_if_to_cond_assign_visitor::visit_enter(ir_if *ir)
+{
+   (void) ir;
+   this->depth++;
+
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_if_to_cond_assign_visitor::visit_leave(ir_if *ir)
+{
+   /* Only flatten when beyond the GPU's maximum supported nesting depth. */
+   if (this->depth-- <= this->max_depth)
+      return visit_continue;
+
+   bool found_control_flow = false;
+   ir_assignment *assign;
+
+   /* Check that both blocks don't contain anything we can't support. */
+   foreach_in_list(ir_instruction, then_ir, &ir->then_instructions) {
+      visit_tree(then_ir, check_control_flow, &found_control_flow);
+   }
+   foreach_in_list(ir_instruction, else_ir, &ir->else_instructions) {
+      visit_tree(else_ir, check_control_flow, &found_control_flow);
+   }
+   if (found_control_flow)
+      return visit_continue;
+
+   void *mem_ctx = ralloc_parent(ir);
+
+   /* Store the condition to a variable.  Move all of the instructions from
+    * the then-clause of the if-statement.  Use the condition variable as a
+    * condition for all assignments.
+    */
+   ir_variable *const then_var =
+      new(mem_ctx) ir_variable(glsl_type::bool_type,
+			       "if_to_cond_assign_then",
+			       ir_var_temporary);
+   ir->insert_before(then_var);
+
+   ir_dereference_variable *then_cond =
+      new(mem_ctx) ir_dereference_variable(then_var);
+
+   assign = new(mem_ctx) ir_assignment(then_cond, ir->condition);
+   ir->insert_before(assign);
+
+   move_block_to_cond_assign(mem_ctx, ir, then_cond,
+			     &ir->then_instructions,
+			     this->condition_variables);
+
+   /* Add the new condition variable to the hash table.  This allows us to
+    * find this variable when lowering other (enclosing) if-statements.
+    */
+   hash_table_insert(this->condition_variables, then_var, then_var);
+
+   /* If there are instructions in the else-clause, store the inverse of the
+    * condition to a variable.  Move all of the instructions from the
+    * else-clause if the if-statement.  Use the (inverse) condition variable
+    * as a condition for all assignments.
+    */
+   if (!ir->else_instructions.is_empty()) {
+      ir_variable *const else_var =
+	 new(mem_ctx) ir_variable(glsl_type::bool_type,
+				  "if_to_cond_assign_else",
+				  ir_var_temporary);
+      ir->insert_before(else_var);
+
+      ir_dereference_variable *else_cond =
+	 new(mem_ctx) ir_dereference_variable(else_var);
+
+      ir_rvalue *inverse =
+	 new(mem_ctx) ir_expression(ir_unop_logic_not,
+				    then_cond->clone(mem_ctx, NULL));
+
+      assign = new(mem_ctx) ir_assignment(else_cond, inverse);
+      ir->insert_before(assign);
+
+      move_block_to_cond_assign(mem_ctx, ir, else_cond,
+				&ir->else_instructions,
+				this->condition_variables);
+
+      /* Add the new condition variable to the hash table.  This allows us to
+       * find this variable when lowering other (enclosing) if-statements.
+       */
+      hash_table_insert(this->condition_variables, else_var, else_var);
+   }
+
+   ir->remove();
+
+   this->progress = true;
+
+   return visit_continue;
+}