kc3-lang/angle/src/compiler/translator/tree_ops/d3d/RewriteElseBlocks.cpp

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• Hash : 382bf288
  Author :
  Date : 2020-12-24T23:56:39
  

  Organize AST transforms per backend
  
  Most of the AST transforms are written as a workaround to an issue that
  affects a single backend.  This change identifies such transforms and
  organizes them by backend.  They are then only built if the respective
  backend is.
  
  Additionally, about half of the GL transforms are due to mac
  workarounds, including the large RewriteRowMajorMatrices transform.
  Mac-specific workarounds are additionally only built on said platform.
  
  This change reduces the ANGLE binary size:
  
  - 106KB in a Vulkan-only build on Linux
  - 27KB in a GL-only build on Android (60KB on Linux)
  
  Bug: chromium:1084580
  Bug: chromium:1161513
  Change-Id: I64b334332c0d4f848756c6538af0d8d96864c7e9
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2601346
  Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
  Reviewed-by: Jamie Madill <jmadill@chromium.org>
  Reviewed-by: Tim Van Patten <timvp@google.com>
  

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• src/compiler/translator/tree_ops/d3d/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/d3d/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 mock
          // 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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