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

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• Hash : 4dd06d5d
  Author :
  Date : 2017-07-05T12:41:06
  

  Set proper symbol ids on temporary symbol nodes
  
  Temporary symbols used to all have symbol id 0. Now they get assigned
  unique symbol ids. This makes it possible to keep track of them
  according to the symbol id instead of their name, paving way to more
  robust AST handling in the future.
  
  BUG=angleproject:1490
  TEST=angle_unittests
  
  Change-Id: I292e2e483cc39173524fd30a30b48c4c808442e5
  Reviewed-on: https://chromium-review.googlesource.com/559335
  Reviewed-by: Jamie Madill <jmadill@chromium.org>
  Reviewed-by: Corentin Wallez <cwallez@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/Intermediate.h"
  #include "compiler/translator/NodeSearch.h"
  #include "compiler/translator/SymbolTable.h"
  
  namespace sh
  {
  
  namespace
  {
  
  class ElseBlockRewriter : public TIntermTraverser
  {
    public:
      ElseBlockRewriter();
  
    protected:
      bool visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *aggregate) override;
      bool visitBlock(Visit visit, TIntermBlock *block) override;
  
    private:
      const TType *mFunctionType;
  
      TIntermNode *rewriteIfElse(TIntermIfElse *ifElse);
  };
  
  ElseBlockRewriter::ElseBlockRewriter() : TIntermTraverser(true, false, true), mFunctionType(nullptr)
  {
  }
  
  bool ElseBlockRewriter::visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *node)
  {
      // Store the current function context (see comment below)
      mFunctionType = ((visit == PreVisit) ? &node->getFunctionPrototype()->getType() : nullptr);
      return true;
  }
  
  bool ElseBlockRewriter::visitBlock(Visit visit, TIntermBlock *node)
  {
      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)
              {
                  (*node->getSequence())[statementIndex] = rewriteIfElse(ifElse);
              }
          }
      }
      return true;
  }
  
  TIntermNode *ElseBlockRewriter::rewriteIfElse(TIntermIfElse *ifElse)
  {
      ASSERT(ifElse != nullptr);
  
      nextTemporaryId();
  
      TIntermDeclaration *storeCondition = createTempInitDeclaration(ifElse->getCondition());
  
      TIntermBlock *falseBlock = nullptr;
  
      TType boolType(EbtBool, EbpUndefined, EvqTemporary);
  
      if (ifElse->getFalseBlock())
      {
          TIntermBlock *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)
          {
              TIntermNode *returnNode =
                  new TIntermBranch(EOpReturn, TIntermTyped::CreateZero(*mFunctionType));
              negatedElse = new TIntermBlock();
              negatedElse->appendStatement(returnNode);
          }
  
          TIntermSymbol *conditionSymbolElse = createTempSymbol(boolType);
          TIntermUnary *negatedCondition     = new TIntermUnary(EOpLogicalNot, conditionSymbolElse);
          TIntermIfElse *falseIfElse =
              new TIntermIfElse(negatedCondition, ifElse->getFalseBlock(), negatedElse);
          falseBlock = TIntermediate::EnsureBlock(falseIfElse);
      }
  
      TIntermSymbol *conditionSymbolSel = createTempSymbol(boolType);
      TIntermIfElse *newIfElse =
          new TIntermIfElse(conditionSymbolSel, ifElse->getTrueBlock(), falseBlock);
  
      TIntermBlock *block = new TIntermBlock();
      block->getSequence()->push_back(storeCondition);
      block->getSequence()->push_back(newIfElse);
  
      return block;
  }
  
  }  // anonymous namespace
  
  void RewriteElseBlocks(TIntermNode *node, TSymbolUniqueId *temporaryId)
  {
      ElseBlockRewriter rewriter;
      rewriter.useTemporaryId(temporaryId);
      node->traverse(&rewriter);
  }
  
  }  // namespace sh
  

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