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

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• Hash : 472c74c6
  Author :
  Date : 2019-08-19T16:32:13
  

  Translator: Allow tree validation in children of TCompiler
  
  This is to be able to perform validation inside TranslatorVulkan, even
  if it's through ASSERTs.
  
  Additionally, every transformation is changed such that they do their
  validation themselves.  TIntermTraverser::updateTree() performs the
  validation, which indirectly validates many of three tree
  transformations.  Some of the more ancient transformations that don't
  use this function directly call TCompiler::validateAST.
  
  Bug: angleproject:2733
  Change-Id: Ie4af029d34e053c5ad1dc8c2c2568eecd625d344
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1761149
  Reviewed-by: Geoff Lang <geofflang@chromium.org>
  Reviewed-by: Jamie Madill <jmadill@chromium.org>
  Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
  

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• src/compiler/translator/tree_ops/RewriteElseBlocks.cpp

• //
  // Copyright 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/tree_ops/RewriteElseBlocks.h"
  
  #include "compiler/translator/Compiler.h"
  #include "compiler/translator/IntermNode.h"
  #include "compiler/translator/SymbolTable.h"
  #include "compiler/translator/tree_util/IntermNode_util.h"
  #include "compiler/translator/tree_util/NodeSearch.h"
  
  namespace sh
  {
  
  namespace
  {
  
  class ElseBlockRewriter : public TIntermTraverser
  {
    public:
      ElseBlockRewriter(TSymbolTable *symbolTable);
  
    protected:
      bool visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *aggregate) override;
      bool visitBlock(Visit visit, TIntermBlock *block) override;
  
    private:
      TIntermNode *rewriteIfElse(TIntermIfElse *ifElse);
  
      const TType *mFunctionType;
  };
  
  ElseBlockRewriter::ElseBlockRewriter(TSymbolTable *symbolTable)
      : TIntermTraverser(true, false, true, symbolTable), 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);
  
      TIntermDeclaration *storeCondition = nullptr;
      TVariable *conditionVariable =
          DeclareTempVariable(mSymbolTable, ifElse->getCondition(), EvqTemporary, &storeCondition);
  
      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, CreateZeroNode(*mFunctionType));
              negatedElse             = new TIntermBlock();
              negatedElse->appendStatement(returnNode);
          }
  
          TIntermSymbol *conditionSymbolElse = CreateTempSymbolNode(conditionVariable);
          TIntermUnary *negatedCondition =
              new TIntermUnary(EOpLogicalNot, conditionSymbolElse, nullptr);
          TIntermIfElse *falseIfElse =
              new TIntermIfElse(negatedCondition, ifElse->getFalseBlock(), negatedElse);
          falseBlock = EnsureBlock(falseIfElse);
      }
  
      TIntermSymbol *conditionSymbolSel = CreateTempSymbolNode(conditionVariable);
      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
  
  bool RewriteElseBlocks(TCompiler *compiler, TIntermNode *node, TSymbolTable *symbolTable)
  {
      ElseBlockRewriter rewriter(symbolTable);
      node->traverse(&rewriter);
  
      return compiler->validateAST(node);
  }
  
  }  // namespace sh
  

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