michael@0: //
michael@0: // Copyright (c) 2002-2013 The ANGLE Project Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: //
michael@0: // UnfoldShortCircuit is an AST traverser to output short-circuiting operators as if-else statements.
michael@0: // The results are assigned to s# temporaries, which are used by the main translator instead of
michael@0: // the original expression.
michael@0: //
michael@0: 
michael@0: #include "compiler/UnfoldShortCircuit.h"
michael@0: 
michael@0: #include "compiler/InfoSink.h"
michael@0: #include "compiler/OutputHLSL.h"
michael@0: 
michael@0: namespace sh
michael@0: {
michael@0: UnfoldShortCircuit::UnfoldShortCircuit(TParseContext &context, OutputHLSL *outputHLSL) : mContext(context), mOutputHLSL(outputHLSL)
michael@0: {
michael@0:     mTemporaryIndex = 0;
michael@0: }
michael@0: 
michael@0: void UnfoldShortCircuit::traverse(TIntermNode *node)
michael@0: {
michael@0:     int rewindIndex = mTemporaryIndex;
michael@0:     node->traverse(this);
michael@0:     mTemporaryIndex = rewindIndex;
michael@0: }
michael@0: 
michael@0: bool UnfoldShortCircuit::visitBinary(Visit visit, TIntermBinary *node)
michael@0: {
michael@0:     TInfoSinkBase &out = mOutputHLSL->getBodyStream();
michael@0: 
michael@0:     switch (node->getOp())
michael@0:     {
michael@0:       case EOpLogicalOr:
michael@0:         // "x || y" is equivalent to "x ? true : y", which unfolds to "bool s; if(x) s = true; else s = y;",
michael@0:         // and then further simplifies down to "bool s = x; if(!s) s = y;".
michael@0:         {
michael@0:             int i = mTemporaryIndex;
michael@0: 
michael@0:             out << "bool s" << i << ";\n";
michael@0: 
michael@0:             out << "{\n";
michael@0: 
michael@0:             mTemporaryIndex = i + 1;
michael@0:             node->getLeft()->traverse(this);
michael@0:             out << "s" << i << " = ";
michael@0:             mTemporaryIndex = i + 1;
michael@0:             node->getLeft()->traverse(mOutputHLSL);
michael@0:             out << ";\n";
michael@0:             out << "if(!s" << i << ")\n"
michael@0:                    "{\n";
michael@0:             mTemporaryIndex = i + 1;
michael@0:             node->getRight()->traverse(this);
michael@0:             out << "    s" << i << " = ";
michael@0:             mTemporaryIndex = i + 1;
michael@0:             node->getRight()->traverse(mOutputHLSL);
michael@0:             out << ";\n"
michael@0:                    "}\n";
michael@0: 
michael@0:             out << "}\n";
michael@0: 
michael@0:             mTemporaryIndex = i + 1;
michael@0:         }
michael@0:         return false;
michael@0:       case EOpLogicalAnd:
michael@0:         // "x && y" is equivalent to "x ? y : false", which unfolds to "bool s; if(x) s = y; else s = false;",
michael@0:         // and then further simplifies down to "bool s = x; if(s) s = y;".
michael@0:         {
michael@0:             int i = mTemporaryIndex;
michael@0: 
michael@0:             out << "bool s" << i << ";\n";
michael@0: 
michael@0:             out << "{\n";
michael@0: 
michael@0:             mTemporaryIndex = i + 1;
michael@0:             node->getLeft()->traverse(this);
michael@0:             out << "s" << i << " = ";
michael@0:             mTemporaryIndex = i + 1;
michael@0:             node->getLeft()->traverse(mOutputHLSL);
michael@0:             out << ";\n";
michael@0:             out << "if(s" << i << ")\n"
michael@0:                    "{\n";
michael@0:             mTemporaryIndex = i + 1;
michael@0:             node->getRight()->traverse(this);
michael@0:             out << "    s" << i << " = ";
michael@0:             mTemporaryIndex = i + 1;
michael@0:             node->getRight()->traverse(mOutputHLSL);
michael@0:             out << ";\n"
michael@0:                    "}\n";
michael@0: 
michael@0:             out << "}\n";
michael@0: 
michael@0:             mTemporaryIndex = i + 1;
michael@0:         }
michael@0:         return false;
michael@0:       default:
michael@0:         return true;
michael@0:     }
michael@0: }
michael@0: 
michael@0: bool UnfoldShortCircuit::visitSelection(Visit visit, TIntermSelection *node)
michael@0: {
michael@0:     TInfoSinkBase &out = mOutputHLSL->getBodyStream();
michael@0: 
michael@0:     // Unfold "b ? x : y" into "type s; if(b) s = x; else s = y;"
michael@0:     if (node->usesTernaryOperator())
michael@0:     {
michael@0:         int i = mTemporaryIndex;
michael@0: 
michael@0:         out << mOutputHLSL->typeString(node->getType()) << " s" << i << ";\n";
michael@0: 
michael@0:         out << "{\n";
michael@0: 
michael@0:         mTemporaryIndex = i + 1;
michael@0:         node->getCondition()->traverse(this);
michael@0:         out << "if(";
michael@0:         mTemporaryIndex = i + 1;
michael@0:         node->getCondition()->traverse(mOutputHLSL);
michael@0:         out << ")\n"
michael@0:                "{\n";
michael@0:         mTemporaryIndex = i + 1;
michael@0:         node->getTrueBlock()->traverse(this);
michael@0:         out << "    s" << i << " = ";
michael@0:         mTemporaryIndex = i + 1;
michael@0:         node->getTrueBlock()->traverse(mOutputHLSL);
michael@0:         out << ";\n"
michael@0:                "}\n"
michael@0:                "else\n"
michael@0:                "{\n";
michael@0:         mTemporaryIndex = i + 1;
michael@0:         node->getFalseBlock()->traverse(this);
michael@0:         out << "    s" << i << " = ";
michael@0:         mTemporaryIndex = i + 1;
michael@0:         node->getFalseBlock()->traverse(mOutputHLSL);
michael@0:         out << ";\n"
michael@0:                "}\n";
michael@0: 
michael@0:         out << "}\n";
michael@0: 
michael@0:         mTemporaryIndex = i + 1;
michael@0:     }
michael@0: 
michael@0:     return false;
michael@0: }
michael@0: 
michael@0: bool UnfoldShortCircuit::visitLoop(Visit visit, TIntermLoop *node)
michael@0: {
michael@0:     int rewindIndex = mTemporaryIndex;
michael@0: 
michael@0:     if (node->getInit())
michael@0:     {
michael@0:         node->getInit()->traverse(this);
michael@0:     }
michael@0:     
michael@0:     if (node->getCondition())
michael@0:     {
michael@0:         node->getCondition()->traverse(this);
michael@0:     }
michael@0: 
michael@0:     if (node->getExpression())
michael@0:     {
michael@0:         node->getExpression()->traverse(this);
michael@0:     }
michael@0: 
michael@0:     mTemporaryIndex = rewindIndex;
michael@0: 
michael@0:     return false;
michael@0: }
michael@0: 
michael@0: int UnfoldShortCircuit::getNextTemporaryIndex()
michael@0: {
michael@0:     return mTemporaryIndex++;
michael@0: }
michael@0: }