kc3-lang/angle/src/compiler/translator/tree_ops/hlsl/UnfoldShortCircuitToIf.cpp

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• Hash : 9b63700b
  Author :
  Date : 2023-07-11T10:25:40
  

  Translator: Reorganize files
  
  This change makes the translator files more organized by:
  
  - Grouping files that are specific to a certain output under their own
    directory,
  - Moving transformations under tree_ops
  - Removing Direct from metal translation now that that SPIR-V Cross path
    is removed
  
  Bug: angleproject:6394
  Change-Id: Iaf5bb8d5604b84748dece029821b1f77b2813967
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4678780
  Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
  Reviewed-by: Geoff Lang <geofflang@chromium.org>
  

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• src/compiler/translator/tree_ops/hlsl/UnfoldShortCircuitToIf.cpp

• //
  // Copyright 2002 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.
  //
  // UnfoldShortCircuitToIf is an AST traverser to convert short-circuiting operators to if-else
  // statements.
  // The results are assigned to s# temporaries, which are used by the main translator instead of
  // the original expression.
  //
  
  #include "compiler/translator/tree_ops/hlsl/UnfoldShortCircuitToIf.h"
  
  #include "compiler/translator/StaticType.h"
  #include "compiler/translator/tree_util/IntermNodePatternMatcher.h"
  #include "compiler/translator/tree_util/IntermNode_util.h"
  #include "compiler/translator/tree_util/IntermTraverse.h"
  
  namespace sh
  {
  
  namespace
  {
  
  // Traverser that unfolds one short-circuiting operation at a time.
  class UnfoldShortCircuitTraverser : public TIntermTraverser
  {
    public:
      UnfoldShortCircuitTraverser(TSymbolTable *symbolTable);
  
      bool visitBinary(Visit visit, TIntermBinary *node) override;
      bool visitTernary(Visit visit, TIntermTernary *node) override;
  
      void nextIteration();
      bool foundShortCircuit() const { return mFoundShortCircuit; }
  
    protected:
      // Marked to true once an operation that needs to be unfolded has been found.
      // After that, no more unfolding is performed on that traversal.
      bool mFoundShortCircuit;
  
      IntermNodePatternMatcher mPatternToUnfoldMatcher;
  };
  
  UnfoldShortCircuitTraverser::UnfoldShortCircuitTraverser(TSymbolTable *symbolTable)
      : TIntermTraverser(true, false, true, symbolTable),
        mFoundShortCircuit(false),
        mPatternToUnfoldMatcher(IntermNodePatternMatcher::kUnfoldedShortCircuitExpression)
  {}
  
  bool UnfoldShortCircuitTraverser::visitBinary(Visit visit, TIntermBinary *node)
  {
      if (mFoundShortCircuit)
          return false;
  
      if (visit != PreVisit)
          return true;
  
      if (!mPatternToUnfoldMatcher.match(node, getParentNode()))
          return true;
  
      // If our right node doesn't have side effects, we know we don't need to unfold this
      // expression: there will be no short-circuiting side effects to avoid
      // (note: unfolding doesn't depend on the left node -- it will always be evaluated)
      ASSERT(node->getRight()->hasSideEffects());
  
      mFoundShortCircuit = true;
  
      switch (node->getOp())
      {
          case EOpLogicalOr:
          {
              // "x || y" is equivalent to "x ? true : y", which unfolds to "bool s; if(x) s = true;
              // else s = y;",
              // and then further simplifies down to "bool s = x; if(!s) s = y;".
  
              TIntermSequence insertions;
              const TType *boolType = StaticType::Get<EbtBool, EbpUndefined, EvqTemporary, 1, 1>();
              TVariable *resultVariable = CreateTempVariable(mSymbolTable, boolType);
  
              ASSERT(node->getLeft()->getType() == *boolType);
              insertions.push_back(CreateTempInitDeclarationNode(resultVariable, node->getLeft()));
  
              TIntermBlock *assignRightBlock = new TIntermBlock();
              ASSERT(node->getRight()->getType() == *boolType);
              assignRightBlock->getSequence()->push_back(
                  CreateTempAssignmentNode(resultVariable, node->getRight()));
  
              TIntermUnary *notTempSymbol =
                  new TIntermUnary(EOpLogicalNot, CreateTempSymbolNode(resultVariable), nullptr);
              TIntermIfElse *ifNode = new TIntermIfElse(notTempSymbol, assignRightBlock, nullptr);
              insertions.push_back(ifNode);
  
              insertStatementsInParentBlock(insertions);
  
              queueReplacement(CreateTempSymbolNode(resultVariable), OriginalNode::IS_DROPPED);
              return false;
          }
          case EOpLogicalAnd:
          {
              // "x && y" is equivalent to "x ? y : false", which unfolds to "bool s; if(x) s = y;
              // else s = false;",
              // and then further simplifies down to "bool s = x; if(s) s = y;".
              TIntermSequence insertions;
              const TType *boolType = StaticType::Get<EbtBool, EbpUndefined, EvqTemporary, 1, 1>();
              TVariable *resultVariable = CreateTempVariable(mSymbolTable, boolType);
  
              ASSERT(node->getLeft()->getType() == *boolType);
              insertions.push_back(CreateTempInitDeclarationNode(resultVariable, node->getLeft()));
  
              TIntermBlock *assignRightBlock = new TIntermBlock();
              ASSERT(node->getRight()->getType() == *boolType);
              assignRightBlock->getSequence()->push_back(
                  CreateTempAssignmentNode(resultVariable, node->getRight()));
  
              TIntermIfElse *ifNode =
                  new TIntermIfElse(CreateTempSymbolNode(resultVariable), assignRightBlock, nullptr);
              insertions.push_back(ifNode);
  
              insertStatementsInParentBlock(insertions);
  
              queueReplacement(CreateTempSymbolNode(resultVariable), OriginalNode::IS_DROPPED);
              return false;
          }
          default:
              UNREACHABLE();
              return true;
      }
  }
  
  bool UnfoldShortCircuitTraverser::visitTernary(Visit visit, TIntermTernary *node)
  {
      if (mFoundShortCircuit)
          return false;
  
      if (visit != PreVisit)
          return true;
  
      if (!mPatternToUnfoldMatcher.match(node))
          return true;
  
      mFoundShortCircuit = true;
  
      // Unfold "b ? x : y" into "type s; if(b) s = x; else s = y;"
      TIntermSequence insertions;
      TIntermDeclaration *tempDeclaration = nullptr;
      TVariable *resultVariable = DeclareTempVariable(mSymbolTable, new TType(node->getType()),
                                                      EvqTemporary, &tempDeclaration);
      insertions.push_back(tempDeclaration);
  
      TIntermBlock *trueBlock = new TIntermBlock();
      TIntermBinary *trueAssignment =
          CreateTempAssignmentNode(resultVariable, node->getTrueExpression());
      trueBlock->getSequence()->push_back(trueAssignment);
  
      TIntermBlock *falseBlock = new TIntermBlock();
      TIntermBinary *falseAssignment =
          CreateTempAssignmentNode(resultVariable, node->getFalseExpression());
      falseBlock->getSequence()->push_back(falseAssignment);
  
      TIntermIfElse *ifNode =
          new TIntermIfElse(node->getCondition()->getAsTyped(), trueBlock, falseBlock);
      insertions.push_back(ifNode);
  
      insertStatementsInParentBlock(insertions);
  
      TIntermSymbol *ternaryResult = CreateTempSymbolNode(resultVariable);
      queueReplacement(ternaryResult, OriginalNode::IS_DROPPED);
  
      return false;
  }
  
  void UnfoldShortCircuitTraverser::nextIteration()
  {
      mFoundShortCircuit = false;
  }
  
  }  // namespace
  
  bool UnfoldShortCircuitToIf(TCompiler *compiler, TIntermNode *root, TSymbolTable *symbolTable)
  {
      UnfoldShortCircuitTraverser traverser(symbolTable);
      // Unfold one operator at a time, and reset the traverser between iterations.
      do
      {
          traverser.nextIteration();
          root->traverse(&traverser);
          if (traverser.foundShortCircuit())
          {
              if (!traverser.updateTree(compiler, root))
              {
                  return false;
              }
          }
      } while (traverser.foundShortCircuit());
  
      return true;
  }
  
  }  // namespace sh
  

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