xref: /external/chromium_org/third_party/mesa/src/src/glsl/ir_expression_flattening.cpp

/*
 * 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 ir_expression_flattening.cpp
 *
 * Takes the leaves of expression trees and makes them dereferences of
 * assignments of the leaves to temporaries, according to a predicate.
 *
 * This is used for breaking down matrix operations, where it's easier to
 * create a temporary and work on each of its vector components individually.
 */

#include "ir.h"
#include "ir_visitor.h"
#include "ir_rvalue_visitor.h"
#include "ir_expression_flattening.h"
#include "glsl_types.h"

class ir_expression_flattening_visitor : public ir_rvalue_visitor {
public:
   ir_expression_flattening_visitor(bool (*predicate)(ir_instruction *ir))
   {
      this->predicate = predicate;
   }

   virtual ~ir_expression_flattening_visitor()
   {
      /* empty */
   }

   void handle_rvalue(ir_rvalue **rvalue);
   bool (*predicate)(ir_instruction *ir);
};

void
do_expression_flattening(exec_list *instructions,
			 bool (*predicate)(ir_instruction *ir))
{
   ir_expression_flattening_visitor v(predicate);

   foreach_iter(exec_list_iterator, iter, *instructions) {
      ir_instruction *ir = (ir_instruction *)iter.get();

      ir->accept(&v);
   }
}

void
ir_expression_flattening_visitor::handle_rvalue(ir_rvalue **rvalue)
{
   ir_variable *var;
   ir_assignment *assign;
   ir_rvalue *ir = *rvalue;

   if (!ir || !this->predicate(ir))
      return;

   void *ctx = ralloc_parent(ir);

   var = new(ctx) ir_variable(ir->type, "flattening_tmp", ir_var_temporary);
   base_ir->insert_before(var);

   assign = new(ctx) ir_assignment(new(ctx) ir_dereference_variable(var),
				   ir,
				   NULL);
   base_ir->insert_before(assign);

   *rvalue = new(ctx) ir_dereference_variable(var);
}