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//
// 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.
//
#include "compiler/translator/UnfoldShortCircuitAST.h"
namespace
{
// "x || y" is equivalent to "x ? true : y".
TIntermSelection *UnfoldOR(TIntermTyped *x, TIntermTyped *y)
{
const TType boolType(EbtBool, EbpUndefined);
ConstantUnion *u = new ConstantUnion;
u->setBConst(true);
TIntermConstantUnion *trueNode = new TIntermConstantUnion(
u, TType(EbtBool, EbpUndefined, EvqConst, 1));
return new TIntermSelection(x, trueNode, y, boolType);
}
// "x && y" is equivalent to "x ? y : false".
TIntermSelection *UnfoldAND(TIntermTyped *x, TIntermTyped *y)
{
const TType boolType(EbtBool, EbpUndefined);
ConstantUnion *u = new ConstantUnion;
u->setBConst(false);
TIntermConstantUnion *falseNode = new TIntermConstantUnion(
u, TType(EbtBool, EbpUndefined, EvqConst, 1));
return new TIntermSelection(x, y, falseNode, boolType);
}
} // namespace anonymous
bool UnfoldShortCircuitAST::visitBinary(Visit visit, TIntermBinary *node)
{
TIntermSelection *replacement = NULL;
switch (node->getOp())
{
case EOpLogicalOr:
replacement = UnfoldOR(node->getLeft(), node->getRight());
break;
case EOpLogicalAnd:
replacement = UnfoldAND(node->getLeft(), node->getRight());
break;
default:
break;
}
if (replacement)
{
replacements.push_back(
NodeUpdateEntry(getParentNode(), node, replacement));
}
return true;
}
void UnfoldShortCircuitAST::updateTree()
{
for (size_t ii = 0; ii < replacements.size(); ++ii)
{
const NodeUpdateEntry& entry = replacements[ii];
ASSERT(entry.parent);
bool replaced = entry.parent->replaceChildNode(
entry.original, entry.replacement);
ASSERT(replaced);
// In AST traversing, a parent is visited before its children.
// After we replace a node, if an immediate child is to
// be replaced, we need to make sure we don't update the replaced
// node; instead, we update the replacement node.
for (size_t jj = ii + 1; jj < replacements.size(); ++jj)
{
NodeUpdateEntry& entry2 = replacements[jj];
if (entry2.parent == entry.original)
entry2.parent = entry.replacement;
}
}
}
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