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

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• Author : Olli Etuaho
  Date : 2015-02-13 13:12:22
  Hash : a3a5cc6a
  Message : Expose the IntermNode tree generated in the compiler for testing This refactoring makes it possible for tests to access the IntermNode tree produced by compilation by calling compileTree(). Removing ParseContext usage from OutputHLSL has the additional benefit of better separation between parsing and output. BUG=angle:916 Change-Id: Ib40954832316328772a5c1dcbbe6b46b238e4e65 Reviewed-on: https://chromium-review.googlesource.com/249723 Reviewed-by: Olli Etuaho <oetuaho@nvidia.com> Tested-by: Olli Etuaho <oetuaho@nvidia.com>

• src/compiler/translator/UnfoldShortCircuit.cpp

• //
  // Copyright (c) 2002-2013 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.
  //
  // UnfoldShortCircuit is an AST traverser to output short-circuiting operators as 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/UnfoldShortCircuit.h"
  
  #include "compiler/translator/InfoSink.h"
  #include "compiler/translator/OutputHLSL.h"
  #include "compiler/translator/UtilsHLSL.h"
  
  namespace sh
  {
  UnfoldShortCircuit::UnfoldShortCircuit(OutputHLSL *outputHLSL) : mOutputHLSL(outputHLSL)
  {
      mTemporaryIndex = 0;
  }
  
  void UnfoldShortCircuit::traverse(TIntermNode *node)
  {
      int rewindIndex = mTemporaryIndex;
      node->traverse(this);
      mTemporaryIndex = rewindIndex;
  }
  
  bool UnfoldShortCircuit::visitBinary(Visit visit, TIntermBinary *node)
  {
      TInfoSinkBase &out = mOutputHLSL->getInfoSink();
  
      // 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)
      if (!node->getRight()->hasSideEffects())
      {
          return 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;".
          {
              int i = mTemporaryIndex;
  
              out << "bool s" << i << ";\n";
  
              out << "{\n";
  
              mTemporaryIndex = i + 1;
              node->getLeft()->traverse(this);
              out << "s" << i << " = ";
              mTemporaryIndex = i + 1;
              node->getLeft()->traverse(mOutputHLSL);
              out << ";\n";
              out << "if (!s" << i << ")\n"
                     "{\n";
              mTemporaryIndex = i + 1;
              node->getRight()->traverse(this);
              out << "    s" << i << " = ";
              mTemporaryIndex = i + 1;
              node->getRight()->traverse(mOutputHLSL);
              out << ";\n"
                     "}\n";
  
              out << "}\n";
  
              mTemporaryIndex = i + 1;
          }
          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;".
          {
              int i = mTemporaryIndex;
  
              out << "bool s" << i << ";\n";
  
              out << "{\n";
  
              mTemporaryIndex = i + 1;
              node->getLeft()->traverse(this);
              out << "s" << i << " = ";
              mTemporaryIndex = i + 1;
              node->getLeft()->traverse(mOutputHLSL);
              out << ";\n";
              out << "if (s" << i << ")\n"
                     "{\n";
              mTemporaryIndex = i + 1;
              node->getRight()->traverse(this);
              out << "    s" << i << " = ";
              mTemporaryIndex = i + 1;
              node->getRight()->traverse(mOutputHLSL);
              out << ";\n"
                     "}\n";
  
              out << "}\n";
  
              mTemporaryIndex = i + 1;
          }
          return false;
        default:
          return true;
      }
  }
  
  bool UnfoldShortCircuit::visitSelection(Visit visit, TIntermSelection *node)
  {
      TInfoSinkBase &out = mOutputHLSL->getInfoSink();
  
      // Unfold "b ? x : y" into "type s; if(b) s = x; else s = y;"
      if (node->usesTernaryOperator())
      {
          int i = mTemporaryIndex;
  
          out << TypeString(node->getType()) << " s" << i << ";\n";
  
          out << "{\n";
  
          mTemporaryIndex = i + 1;
          node->getCondition()->traverse(this);
          out << "if (";
          mTemporaryIndex = i + 1;
          node->getCondition()->traverse(mOutputHLSL);
          out << ")\n"
                 "{\n";
          mTemporaryIndex = i + 1;
          node->getTrueBlock()->traverse(this);
          out << "    s" << i << " = ";
          mTemporaryIndex = i + 1;
          node->getTrueBlock()->traverse(mOutputHLSL);
          out << ";\n"
                 "}\n"
                 "else\n"
                 "{\n";
          mTemporaryIndex = i + 1;
          node->getFalseBlock()->traverse(this);
          out << "    s" << i << " = ";
          mTemporaryIndex = i + 1;
          node->getFalseBlock()->traverse(mOutputHLSL);
          out << ";\n"
                 "}\n";
  
          out << "}\n";
  
          mTemporaryIndex = i + 1;
      }
  
      return false;
  }
  
  bool UnfoldShortCircuit::visitLoop(Visit visit, TIntermLoop *node)
  {
      int rewindIndex = mTemporaryIndex;
  
      if (node->getInit())
      {
          node->getInit()->traverse(this);
      }
      
      if (node->getCondition())
      {
          node->getCondition()->traverse(this);
      }
  
      if (node->getExpression())
      {
          node->getExpression()->traverse(this);
      }
  
      mTemporaryIndex = rewindIndex;
  
      return false;
  }
  
  int UnfoldShortCircuit::getNextTemporaryIndex()
  {
      return mTemporaryIndex++;
  }
  }