ir_constant_expression.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_expression.cpp
  26  * Evaluate and process constant valued expressions
  27  *
  28  * In GLSL, constant valued expressions are used in several places.  These
  29  * must be processed and evaluated very early in the compilation process.
  30  *
  31  *    * Sizes of arrays
  32  *    * Initializers for uniforms
  33  *    * Initializers for \c const variables
  34  */
  35
  36 #define NULL 0
  37 #include "ir.h"
  38 #include "ir_visitor.h"
  39
  40 /**
  41  * Visitor class for evaluating constant expressions
  42  */
  43 class ir_constant_visitor : public ir_visitor {
  44 public:
  45    ir_constant_visitor()
  46       : value(NULL)
  47    {
  48       /* empty */
  49    }
  50
  51    virtual ~ir_constant_visitor()
  52    {
  53       /* empty */
  54    }
  55
  56    /**
  57     * \name Visit methods
  58     *
  59     * As typical for the visitor pattern, there must be one \c visit method for
  60     * each concrete subclass of \c ir_instruction.  Virtual base classes within
  61     * the hierarchy should not have \c visit methods.
  62     */
  63    /*@{*/
  64    virtual void visit(ir_variable *);
  65    virtual void visit(ir_label *);
  66    virtual void visit(ir_function_signature *);
  67    virtual void visit(ir_function *);
  68    virtual void visit(ir_expression *);
  69    virtual void visit(ir_swizzle *);
  70    virtual void visit(ir_dereference *);
  71    virtual void visit(ir_assignment *);
  72    virtual void visit(ir_constant *);
  73    virtual void visit(ir_call *);
  74    virtual void visit(ir_return *);
  75    virtual void visit(ir_if *);
  76    /*@}*/
  77
  78    /**
  79     * Value of the constant expression.
  80     *
  81     * \note
  82     * This field will be \c NULL if the expression is not constant valued.
  83     */
  84    /* FINIHSME: This cannot hold values for constant arrays or structures. */
  85    ir_constant *value;
  86 };
  87
  88
  89 ir_constant *
  90 ir_instruction::constant_expression_value()
  91 {
  92    ir_constant_visitor visitor;
  93
  94    this->accept(& visitor);
  95    return visitor.value;
  96 }
  97
  98
  99 void
 100 ir_constant_visitor::visit(ir_variable *ir)
 101 {
 102    (void) ir;
 103    value = NULL;
 104 }
 105
 106
 107 void
 108 ir_constant_visitor::visit(ir_label *ir)
 109 {
 110    (void) ir;
 111    value = NULL;
 112 }
 113
 114
 115 void
 116 ir_constant_visitor::visit(ir_function_signature *ir)
 117 {
 118    (void) ir;
 119    value = NULL;
 120 }
 121
 122
 123 void
 124 ir_constant_visitor::visit(ir_function *ir)
 125 {
 126    (void) ir;
 127    value = NULL;
 128 }
 129
 130
 131 void
 132 ir_constant_visitor::visit(ir_expression *ir)
 133 {
 134    (void) ir;
 135    value = NULL;
 136 }
 137
 138
 139 void
 140 ir_constant_visitor::visit(ir_swizzle *ir)
 141 {
 142    (void) ir;
 143    value = NULL;
 144 }
 145
 146
 147 void
 148 ir_constant_visitor::visit(ir_dereference *ir)
 149 {
 150    (void) ir;
 151    value = NULL;
 152 }
 153
 154
 155 void
 156 ir_constant_visitor::visit(ir_assignment *ir)
 157 {
 158    (void) ir;
 159    value = NULL;
 160 }
 161
 162
 163 void
 164 ir_constant_visitor::visit(ir_constant *ir)
 165 {
 166    value = ir;
 167 }
 168
 169
 170 void
 171 ir_constant_visitor::visit(ir_call *ir)
 172 {
 173    (void) ir;
 174    value = NULL;
 175 }
 176
 177
 178 void
 179 ir_constant_visitor::visit(ir_return *ir)
 180 {
 181    (void) ir;
 182    value = NULL;
 183 }
 184
 185
 186 void
 187 ir_constant_visitor::visit(ir_if *ir)
 188 {
 189    (void) ir;
 190    value = NULL;
 191 }