kc3-lang/angle/src/compiler/translator/RewriteElseBlocks.cpp

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• Hash : 5796127e
  Author :
  Date : 2016-09-14T13:57:46
  

  Rename TIntermSelection to TIntermIfElse
  
  Now that ternary nodes are not represented by TIntermSelection any
  more, TIntermIfElse is an easier name to understand for newcomers to
  the code.
  
  BUG=angleproject:1490
  TEST=angle_unittests
  
  Change-Id: Ia1e04e356ab93409400245092a84533d7dfd129d
  Reviewed-on: https://chromium-review.googlesource.com/385416
  Reviewed-by: Corentin Wallez <cwallez@chromium.org>
  Reviewed-by: Jamie Madill <jmadill@chromium.org>
  Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
  

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• src/compiler/translator/RewriteElseBlocks.cpp

• //
  // Copyright (c) 2014 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  // RewriteElseBlocks.cpp: Implementation for tree transform to change
  //   all if-else blocks to if-if blocks.
  //
  
  #include "compiler/translator/RewriteElseBlocks.h"
  #include "compiler/translator/NodeSearch.h"
  #include "compiler/translator/SymbolTable.h"
  
  namespace sh
  {
  
  namespace
  {
  
  class ElseBlockRewriter : public TIntermTraverser
  {
    public:
      ElseBlockRewriter();
  
    protected:
      bool visitAggregate(Visit visit, TIntermAggregate *aggregate) override;
  
    private:
      const TType *mFunctionType;
  
      TIntermNode *rewriteIfElse(TIntermIfElse *ifElse);
  };
  
  ElseBlockRewriter::ElseBlockRewriter()
      : TIntermTraverser(true, false, true),
        mFunctionType(NULL)
  {}
  
  bool ElseBlockRewriter::visitAggregate(Visit visit, TIntermAggregate *node)
  {
      switch (node->getOp())
      {
        case EOpSequence:
          if (visit == PostVisit)
          {
              for (size_t statementIndex = 0; statementIndex != node->getSequence()->size(); statementIndex++)
              {
                  TIntermNode *statement = (*node->getSequence())[statementIndex];
                  TIntermIfElse *ifElse  = statement->getAsIfElseNode();
                  if (ifElse && ifElse->getFalseBlock() != nullptr)
                  {
                      // Check for if / else if
                      TIntermIfElse *elseIfBranch = ifElse->getFalseBlock()->getAsIfElseNode();
                      if (elseIfBranch)
                      {
                          ifElse->replaceChildNode(elseIfBranch, rewriteIfElse(elseIfBranch));
                          delete elseIfBranch;
                      }
  
                      (*node->getSequence())[statementIndex] = rewriteIfElse(ifElse);
                      delete ifElse;
                  }
              }
          }
          break;
  
        case EOpFunction:
          // Store the current function context (see comment below)
          mFunctionType = ((visit == PreVisit) ? &node->getType() : NULL);
          break;
  
        default: break;
      }
  
      return true;
  }
  
  TIntermNode *ElseBlockRewriter::rewriteIfElse(TIntermIfElse *ifElse)
  {
      ASSERT(ifElse != nullptr);
  
      nextTemporaryIndex();
  
      TIntermTyped *typedCondition     = ifElse->getCondition()->getAsTyped();
      TIntermAggregate *storeCondition = createTempInitDeclaration(typedCondition);
  
      TIntermIfElse *falseBlock = nullptr;
  
      TType boolType(EbtBool, EbpUndefined, EvqTemporary);
  
      if (ifElse->getFalseBlock())
      {
          TIntermAggregate *negatedElse = nullptr;
          // crbug.com/346463
          // D3D generates error messages claiming a function has no return value, when rewriting
          // an if-else clause that returns something non-void in a function. By appending dummy
          // returns (that are unreachable) we can silence this compile error.
          if (mFunctionType && mFunctionType->getBasicType() != EbtVoid)
          {
              TString typeString = mFunctionType->getStruct() ? mFunctionType->getStruct()->name() :
                  mFunctionType->getBasicString();
              TString rawText = "return (" + typeString + ")0";
              TIntermRaw *returnNode = new TIntermRaw(*mFunctionType, rawText);
              negatedElse = new TIntermAggregate(EOpSequence);
              negatedElse->getSequence()->push_back(returnNode);
          }
  
          TIntermSymbol *conditionSymbolElse = createTempSymbol(boolType);
          TIntermUnary *negatedCondition     = new TIntermUnary(EOpLogicalNot, conditionSymbolElse);
          falseBlock = new TIntermIfElse(negatedCondition, ifElse->getFalseBlock(), negatedElse);
      }
  
      TIntermSymbol *conditionSymbolSel = createTempSymbol(boolType);
      TIntermIfElse *newIfElse =
          new TIntermIfElse(conditionSymbolSel, ifElse->getTrueBlock(), falseBlock);
  
      TIntermAggregate *block = new TIntermAggregate(EOpSequence);
      block->getSequence()->push_back(storeCondition);
      block->getSequence()->push_back(newIfElse);
  
      return block;
  }
  
  }
  
  void RewriteElseBlocks(TIntermNode *node, unsigned int *temporaryIndex)
  {
      ElseBlockRewriter rewriter;
      rewriter.useTemporaryIndex(temporaryIndex);
      node->traverse(&rewriter);
  }
  
  }
  

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