src/compiler/glsl/ir_expression_flattening.cpp

/*
 * Copyright © 2010 Intel Corporation
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 * The above copyright notice and this permission notice (including the next
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 * Software.
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 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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/**
 * \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_rvalue_visitor.h"
#include "ir_expression_flattening.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_in_list(ir_instruction, ir, instructions) {
      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);
}