ir_constant_folding.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_constant_folding.cpp
  26  * Replace constant-valued expressions with references to constant values.
  27  */
  28
  29 #include "ir.h"
  30 #include "ir_visitor.h"
  31 #include "ir_optimization.h"
  32 #include "glsl_types.h"
  33
  34 /**
  35  * Visitor class for replacing expressions with ir_constant values.
  36  */
  37
  38 class ir_constant_folding_visitor : public ir_visitor {
  39 public:
  40    ir_constant_folding_visitor()
  41    {
  42       /* empty */
  43    }
  44
  45    virtual ~ir_constant_folding_visitor()
  46    {
  47       /* empty */
  48    }
  49
  50    /**
  51     * \name Visit methods
  52     *
  53     * As typical for the visitor pattern, there must be one \c visit method for
  54     * each concrete subclass of \c ir_instruction.  Virtual base classes within
  55     * the hierarchy should not have \c visit methods.
  56     */
  57    /*@{*/
  58    virtual void visit(ir_variable *);
  59    virtual void visit(ir_function_signature *);
  60    virtual void visit(ir_function *);
  61    virtual void visit(ir_expression *);
  62    virtual void visit(ir_texture *);
  63    virtual void visit(ir_swizzle *);
  64    virtual void visit(ir_dereference_variable *);
  65    virtual void visit(ir_dereference_array *);
  66    virtual void visit(ir_dereference_record *);
  67    virtual void visit(ir_assignment *);
  68    virtual void visit(ir_constant *);
  69    virtual void visit(ir_call *);
  70    virtual void visit(ir_return *);
  71    virtual void visit(ir_if *);
  72    virtual void visit(ir_loop *);
  73    virtual void visit(ir_loop_jump *);
  74    /*@}*/
  75 };
  76
  77 void
  78 ir_constant_folding_visitor::visit(ir_variable *ir)
  79 {
  80    (void) ir;
  81 }
  82
  83
  84 void
  85 ir_constant_folding_visitor::visit(ir_function_signature *ir)
  86 {
  87    visit_exec_list(&ir->body, this);
  88 }
  89
  90
  91 void
  92 ir_constant_folding_visitor::visit(ir_function *ir)
  93 {
  94    foreach_iter(exec_list_iterator, iter, *ir) {
  95       ir_function_signature *const sig = (ir_function_signature *) iter.get();
  96       sig->accept(this);
  97    }
  98 }
  99
 100 void
 101 ir_constant_folding_visitor::visit(ir_expression *ir)
 102 {
 103    ir_constant *op[2];
 104    unsigned int operand;
 105
 106    for (operand = 0; operand < ir->get_num_operands(); operand++) {
 107       op[operand] = ir->operands[operand]->constant_expression_value();
 108       if (op[operand]) {
 109          ir->operands[operand] = op[operand];
 110       } else {
 111          ir->operands[operand]->accept(this);
 112       }
 113    }
 114 }
 115
 116
 117 void
 118 ir_constant_folding_visitor::visit(ir_texture *ir)
 119 {
 120    // FINISHME: Do stuff with texture lookups
 121    (void) ir;
 122 }
 123
 124
 125 void
 126 ir_constant_folding_visitor::visit(ir_swizzle *ir)
 127 {
 128    ir->val->accept(this);
 129 }
 130
 131
 132 void
 133 ir_constant_folding_visitor::visit(ir_dereference_variable *ir)
 134 {
 135    (void) ir;
 136 }
 137
 138
 139 void
 140 ir_constant_folding_visitor::visit(ir_dereference_array *ir)
 141 {
 142    ir_constant *const_val =
 143       ir->array_index->constant_expression_value();
 144
 145    if (const_val)
 146       ir->array_index = const_val;
 147    else
 148       ir->array_index->accept(this);
 149
 150    ir->array->accept(this);
 151 }
 152
 153
 154 void
 155 ir_constant_folding_visitor::visit(ir_dereference_record *ir)
 156 {
 157    ir->record->accept(this);
 158 }
 159
 160
 161 void
 162 ir_constant_folding_visitor::visit(ir_assignment *ir)
 163 {
 164    ir_constant *const_val = ir->rhs->constant_expression_value();
 165    if (const_val)
 166       ir->rhs = const_val;
 167    else
 168       ir->rhs->accept(this);
 169 }
 170
 171
 172 void
 173 ir_constant_folding_visitor::visit(ir_constant *ir)
 174 {
 175    (void) ir;
 176 }
 177
 178
 179 void
 180 ir_constant_folding_visitor::visit(ir_call *ir)
 181 {
 182    (void) ir;
 183 }
 184
 185
 186 void
 187 ir_constant_folding_visitor::visit(ir_return *ir)
 188 {
 189    (void) ir;
 190 }
 191
 192
 193 void
 194 ir_constant_folding_visitor::visit(ir_if *ir)
 195 {
 196    ir_constant *const_val = ir->condition->constant_expression_value();
 197    if (const_val)
 198       ir->condition = const_val;
 199    else
 200       ir->condition->accept(this);
 201
 202    visit_exec_list(&ir->then_instructions, this);
 203    visit_exec_list(&ir->else_instructions, this);
 204 }
 205
 206
 207 void
 208 ir_constant_folding_visitor::visit(ir_loop *ir)
 209 {
 210    (void) ir;
 211 }
 212
 213
 214 void
 215 ir_constant_folding_visitor::visit(ir_loop_jump *ir)
 216 {
 217    (void) ir;
 218 }
 219
 220 bool
 221 do_constant_folding(exec_list *instructions)
 222 {
 223    ir_constant_folding_visitor constant_folding;
 224
 225    visit_exec_list(instructions, &constant_folding);
 226
 227    /* FINISHME: Return real progress. */
 228    return false;
 229 }