src/glsl/ir_expression_flattening.cpp

   1 /*
   2  * Copyright © 2010 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 /**
  25  * \file ir_expression_flattening.cpp
  26  *
  27  * Takes the leaves of expression trees and makes them dereferences of
  28  * assignments of the leaves to temporaries, according to a predicate.
  29  *
  30  * This is used for breaking down matrix operations, where it's easier to
  31  * create a temporary and work on each of its vector components individually.
  32  */
  33
  34 #include "ir.h"
  35 #include "ir_visitor.h"
  36 #include "ir_rvalue_visitor.h"
  37 #include "ir_expression_flattening.h"
  38 #include "glsl_types.h"
  39
  40 class ir_expression_flattening_visitor : public ir_rvalue_visitor {
  41 public:
  42    ir_expression_flattening_visitor(bool (*predicate)(ir_instruction *ir))
  43    {
  44       this->predicate = predicate;
  45    }
  46
  47    virtual ~ir_expression_flattening_visitor()
  48    {
  49       /* empty */
  50    }
  51
  52    void handle_rvalue(ir_rvalue **rvalue);
  53    bool (*predicate)(ir_instruction *ir);
  54 };
  55
  56 void
  57 do_expression_flattening(exec_list *instructions,
  58                          bool (*predicate)(ir_instruction *ir))
  59 {
  60    ir_expression_flattening_visitor v(predicate);
  61
  62    foreach_list(n, instructions) {
  63       ir_instruction *ir = (ir_instruction *) n;
  64
  65       ir->accept(&v);
  66    }
  67 }
  68
  69 void
  70 ir_expression_flattening_visitor::handle_rvalue(ir_rvalue **rvalue)
  71 {
  72    ir_variable *var;
  73    ir_assignment *assign;
  74    ir_rvalue *ir = *rvalue;
  75
  76    if (!ir || !this->predicate(ir))
  77       return;
  78
  79    void *ctx = ralloc_parent(ir);
  80
  81    var = new(ctx) ir_variable(ir->type, "flattening_tmp", ir_var_temporary);
  82    base_ir->insert_before(var);
  83
  84    assign = new(ctx) ir_assignment(new(ctx) ir_dereference_variable(var),
  85                                    ir,
  86                                    NULL);
  87    base_ir->insert_before(assign);
  88
  89    *rvalue = new(ctx) ir_dereference_variable(var);
  90 }