src/third_party/angle/src/compiler/translator/RewriteElseBlocks.cpp

   1 //
   2 // Copyright (c) 2014 The ANGLE Project Authors. All rights reserved.
   3 // Use of this source code is governed by a BSD-style license that can be
   4 // found in the LICENSE file.
   5 //
   6 // RewriteElseBlocks.cpp: Implementation for tree transform to change
   7 //   all if-else blocks to if-if blocks.
   8 //
   9
  10 #include "compiler/translator/RewriteElseBlocks.h"
  11 #include "compiler/translator/NodeSearch.h"
  12 #include "compiler/translator/SymbolTable.h"
  13
  14 namespace sh
  15 {
  16
  17 TIntermSymbol *MakeNewTemporary(const TString &name, TBasicType type)
  18 {
  19     TType variableType(type, EbpHigh, EvqInternal);
  20     return new TIntermSymbol(-1, name, variableType);
  21 }
  22
  23 TIntermBinary *MakeNewBinary(TOperator op, TIntermTyped *left, TIntermTyped *right, const TType &resultType)
  24 {
  25     TIntermBinary *binary = new TIntermBinary(op);
  26     binary->setLeft(left);
  27     binary->setRight(right);
  28     binary->setType(resultType);
  29     return binary;
  30 }
  31
  32 TIntermUnary *MakeNewUnary(TOperator op, TIntermTyped *operand)
  33 {
  34     TIntermUnary *unary = new TIntermUnary(op, operand->getType());
  35     unary->setOperand(operand);
  36     return unary;
  37 }
  38
  39 bool ElseBlockRewriter::visitAggregate(Visit visit, TIntermAggregate *node)
  40 {
  41     switch (node->getOp())
  42     {
  43       case EOpSequence:
  44         {
  45             for (size_t statementIndex = 0; statementIndex != node->getSequence().size(); statementIndex++)
  46             {
  47                 TIntermNode *statement = node->getSequence()[statementIndex];
  48                 TIntermSelection *selection = statement->getAsSelectionNode();
  49                 if (selection && selection->getFalseBlock() != NULL)
  50                 {
  51                     node->getSequence()[statementIndex] = rewriteSelection(selection);
  52                     delete selection;
  53                 }
  54             }
  55         }
  56         break;
  57
  58       default: break;
  59     }
  60
  61     return true;
  62 }
  63
  64 TIntermNode *ElseBlockRewriter::rewriteSelection(TIntermSelection *selection)
  65 {
  66     ASSERT(selection->getFalseBlock() != NULL);
  67
  68     TString temporaryName = "cond_" + str(mTemporaryIndex++);
  69     TIntermTyped *typedCondition = selection->getCondition()->getAsTyped();
  70     TType resultType(EbtBool, EbpUndefined);
  71     TIntermSymbol *conditionSymbolA = MakeNewTemporary(temporaryName, EbtBool);
  72     TIntermSymbol *conditionSymbolB = MakeNewTemporary(temporaryName, EbtBool);
  73     TIntermSymbol *conditionSymbolC = MakeNewTemporary(temporaryName, EbtBool);
  74     TIntermBinary *storeCondition = MakeNewBinary(EOpInitialize, conditionSymbolA,
  75                                                   typedCondition, resultType);
  76     TIntermUnary *negatedCondition = MakeNewUnary(EOpLogicalNot, conditionSymbolB);
  77     TIntermSelection *falseBlock = new TIntermSelection(negatedCondition,
  78                                                         selection->getFalseBlock(), NULL);
  79     TIntermSelection *newIfElse = new TIntermSelection(conditionSymbolC,
  80                                                        selection->getTrueBlock(), falseBlock);
  81
  82     TIntermAggregate *declaration = new TIntermAggregate(EOpDeclaration);
  83     declaration->getSequence().push_back(storeCondition);
  84
  85     TIntermAggregate *block = new TIntermAggregate(EOpSequence);
  86     block->getSequence().push_back(declaration);
  87     block->getSequence().push_back(newIfElse);
  88
  89     return block;
  90 }
  91
  92 void RewriteElseBlocks(TIntermNode *node)
  93 {
  94     ElseBlockRewriter rewriter;
  95     node->traverse(&rewriter);
  96 }
  97
  98 }