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

• //
  // Copyright 2017 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.
  //
  // WrapSwitchStatementsInBlocks.cpp: Wrap switch statements in blocks and declare all switch-scoped
  // variables there to make the AST compatible with HLSL output.
  //
  // switch (init)
  // {
  //     case 0:
  //         float f;
  //     default:
  //         f = 1.0;
  // }
  //
  // becomes
  //
  // {
  //     float f;
  //     switch (init)
  //     {
  //         case 0:
  //         default:
  //             f = 1.0;
  //     }
  // }
  
  #include "compiler/translator/tree_ops/d3d/WrapSwitchStatementsInBlocks.h"
  
  #include "compiler/translator/IntermNode.h"
  #include "compiler/translator/tree_util/IntermTraverse.h"
  
  namespace sh
  {
  
  namespace
  {
  
  class WrapSwitchStatementsInBlocksTraverser : public TIntermTraverser
  {
    public:
      WrapSwitchStatementsInBlocksTraverser() : TIntermTraverser(true, false, false) {}
  
      bool visitSwitch(Visit visit, TIntermSwitch *node) override;
  };
  
  bool WrapSwitchStatementsInBlocksTraverser::visitSwitch(Visit, TIntermSwitch *node)
  {
      std::vector<TIntermDeclaration *> declarations;
      TIntermSequence *statementList = node->getStatementList()->getSequence();
      for (TIntermNode *statement : *statementList)
      {
          TIntermDeclaration *asDeclaration = statement->getAsDeclarationNode();
          if (asDeclaration)
          {
              declarations.push_back(asDeclaration);
          }
      }
      if (declarations.empty())
      {
          // We don't need to wrap the switch if it doesn't contain declarations as its direct
          // descendants.
          return true;
      }
  
      TIntermBlock *wrapperBlock = new TIntermBlock();
      for (TIntermDeclaration *declaration : declarations)
      {
          // SeparateDeclarations should have already been run.
          ASSERT(declaration->getSequence()->size() == 1);
  
          TIntermDeclaration *declarationInBlock = new TIntermDeclaration();
          TIntermSymbol *declaratorAsSymbol = declaration->getSequence()->at(0)->getAsSymbolNode();
          if (declaratorAsSymbol)
          {
              // This is a simple declaration like: "float f;"
              // Remove the declaration from inside the switch and put it in the wrapping block.
              TIntermSequence emptyReplacement;
              mMultiReplacements.push_back(NodeReplaceWithMultipleEntry(
                  node->getStatementList(), declaration, emptyReplacement));
  
              declarationInBlock->appendDeclarator(declaratorAsSymbol->deepCopy());
              // The declaration can't be the last statement inside the switch since unused variables
              // should already have been pruned.
              ASSERT(declaration != statementList->back());
          }
          else
          {
              // This is an init declaration like: "float f = 0.0;"
              // Change the init declaration inside the switch into an assignment and put a plain
              // declaration in the wrapping block.
              TIntermBinary *declaratorAsBinary =
                  declaration->getSequence()->at(0)->getAsBinaryNode();
              ASSERT(declaratorAsBinary);
  
              TIntermBinary *initAssignment = new TIntermBinary(
                  EOpAssign, declaratorAsBinary->getLeft(), declaratorAsBinary->getRight());
  
              queueReplacementWithParent(node->getStatementList(), declaration, initAssignment,
                                         OriginalNode::IS_DROPPED);
  
              declarationInBlock->appendDeclarator(declaratorAsBinary->getLeft()->deepCopy());
          }
          wrapperBlock->appendStatement(declarationInBlock);
      }
  
      wrapperBlock->appendStatement(node);
      queueReplacement(wrapperBlock, OriginalNode::BECOMES_CHILD);
  
      // Should be fine to process multiple switch statements, even nesting ones in the same
      // traversal.
      return true;
  }
  
  }  // anonymous namespace
  
  // Wrap switch statements in the AST into blocks when needed.
  bool WrapSwitchStatementsInBlocks(TCompiler *compiler, TIntermBlock *root)
  {
      WrapSwitchStatementsInBlocksTraverser traverser;
      root->traverse(&traverser);
      return traverser.updateTree(compiler, root);
  }
  
  }  // namespace sh
  

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