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 automatic function inlining, where we want to take
  31  * an expression containing a call and move the call out to its own
  32  * assignment so that we can inline it at the appropriate place in the
  33  * instruction stream.
  34  */
  35
  36 #define NULL 0
  37 #include "ir.h"
  38 #include "ir_visitor.h"
  39 #include "ir_expression_flattening.h"
  40 #include "glsl_types.h"
  41
  42 class ir_expression_flattening_visitor : public ir_hierarchical_visitor {
  43 public:
  44    ir_expression_flattening_visitor(ir_instruction *base_ir,
  45                                     bool (*predicate)(ir_instruction *ir))
  46    {
  47       this->base_ir = base_ir;
  48       this->predicate = predicate;
  49    }
  50
  51    virtual ~ir_expression_flattening_visitor()
  52    {
  53       /* empty */
  54    }
  55
  56    virtual ir_visitor_status visit_enter(ir_call *);
  57    virtual ir_visitor_status visit_enter(ir_return *);
  58    virtual ir_visitor_status visit_enter(ir_function_signature *);
  59    virtual ir_visitor_status visit_enter(ir_if *);
  60    virtual ir_visitor_status visit_enter(ir_loop *);
  61    virtual ir_visitor_status visit_leave(ir_expression *);
  62    virtual ir_visitor_status visit_leave(ir_swizzle *);
  63
  64    bool (*predicate)(ir_instruction *ir);
  65    ir_instruction *base_ir;
  66 };
  67
  68 void
  69 do_expression_flattening(exec_list *instructions,
  70                          bool (*predicate)(ir_instruction *ir))
  71 {
  72    foreach_iter(exec_list_iterator, iter, *instructions) {
  73       ir_instruction *ir = (ir_instruction *)iter.get();
  74
  75       ir_expression_flattening_visitor v(ir, predicate);
  76       ir->accept(&v);
  77    }
  78 }
  79
  80
  81 static ir_rvalue *
  82 operand_to_temp(ir_instruction *base_ir, ir_rvalue *ir)
  83 {
  84    ir_variable *var;
  85    ir_assignment *assign;
  86
  87    var = new ir_variable(ir->type, "flattening_tmp");
  88    base_ir->insert_before(var);
  89
  90    assign = new ir_assignment(new ir_dereference_variable(var),
  91                               ir,
  92                               NULL);
  93    base_ir->insert_before(assign);
  94
  95    return new ir_dereference_variable(var);
  96 }
  97
  98 ir_visitor_status
  99 ir_expression_flattening_visitor::visit_enter(ir_function_signature *ir)
 100 {
 101    do_expression_flattening(&ir->body, this->predicate);
 102
 103    return visit_continue_with_parent;
 104 }
 105
 106 ir_visitor_status
 107 ir_expression_flattening_visitor::visit_enter(ir_loop *ir)
 108 {
 109    do_expression_flattening(&ir->body_instructions, this->predicate);
 110
 111    return visit_continue_with_parent;
 112 }
 113
 114 ir_visitor_status
 115 ir_expression_flattening_visitor::visit_enter(ir_if *ir)
 116 {
 117    ir->condition->accept(this);
 118
 119    do_expression_flattening(&ir->then_instructions, this->predicate);
 120    do_expression_flattening(&ir->else_instructions, this->predicate);
 121
 122    return visit_continue_with_parent;
 123 }
 124
 125 ir_visitor_status
 126 ir_expression_flattening_visitor::visit_leave(ir_expression *ir)
 127 {
 128    unsigned int operand;
 129
 130    for (operand = 0; operand < ir->get_num_operands(); operand++) {
 131       /* If the operand matches the predicate, then we'll assign its
 132        * value to a temporary and deref the temporary as the operand.
 133        */
 134       if (this->predicate(ir->operands[operand])) {
 135          ir->operands[operand] = operand_to_temp(base_ir,
 136                                                  ir->operands[operand]);
 137       }
 138    }
 139
 140    return visit_continue;
 141 }
 142
 143 ir_visitor_status
 144 ir_expression_flattening_visitor::visit_leave(ir_swizzle *ir)
 145 {
 146    if (this->predicate(ir->val)) {
 147       ir->val = operand_to_temp(this->base_ir, ir->val);
 148    }
 149
 150    return visit_continue;
 151 }
 152
 153 ir_visitor_status
 154 ir_expression_flattening_visitor::visit_enter(ir_call *ir)
 155 {
 156    /* FINISHME: Why not process the call parameters? (Same behavior as original
 157     * FINISHME: code.)
 158     */
 159    (void) ir;
 160    return visit_continue_with_parent;
 161 }
 162
 163
 164 ir_visitor_status
 165 ir_expression_flattening_visitor::visit_enter(ir_return *ir)
 166 {
 167    /* FINISHME: Why not process the return value? (Same behavior as original
 168     * FINISHME: code.)
 169     */
 170    (void) ir;
 171    return visit_continue_with_parent;
 172 }