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

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• Hash : 32aab01d
  Author :
  Date : 2015-01-27T14:12:26
  

  Use a stack for OutputHLSL info log output.
  
  Previously we would always reference mBody in several intermediate
  output methods. This made using these traversals from within the
  header, or for utility methods, very difficult. Instead, use a stack
  where we write to the top InfoLog, and can push/pop from the stack.
  This gives us more flexibility.
  
  BUG=angle:878
  
  Change-Id: I8a6c0382bad18b44d75158274c701db13d4d4e65
  Reviewed-on: https://chromium-review.googlesource.com/243580
  Tested-by: Jamie Madill <jmadill@chromium.org>
  Reviewed-by: Zhenyao Mo <zmo@chromium.org>
  

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• 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(TParseContext &context, OutputHLSL *outputHLSL) : mContext(context), 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++;
  }
  }
  

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