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//
// Copyright (c) 2016 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.
//
// Implementation of evaluating unary integer variable bug workaround.
// See header for more info.
#include "compiler/translator/RewriteUnaryMinusOperatorInt.h"
#include "compiler/translator/IntermTraverse.h"
namespace sh
{
namespace
{
class Traverser : public TIntermTraverser
{
public:
static void Apply(TIntermNode *root);
private:
Traverser();
bool visitUnary(Visit visit, TIntermUnary *node) override;
void nextIteration();
bool mFound = false;
};
// static
void Traverser::Apply(TIntermNode *root)
{
Traverser traverser;
do
{
traverser.nextIteration();
root->traverse(&traverser);
if (traverser.mFound)
{
traverser.updateTree();
}
} while (traverser.mFound);
}
Traverser::Traverser() : TIntermTraverser(true, false, false)
{
}
void Traverser::nextIteration()
{
mFound = false;
}
bool Traverser::visitUnary(Visit visit, TIntermUnary *node)
{
if (mFound)
{
return false;
}
// Decide if the current unary operator is unary minus.
if (node->getOp() != EOpNegative)
{
return true;
}
// Decide if the current operand is an integer variable.
TIntermTyped *opr = node->getOperand();
if (!opr->getType().isScalarInt())
{
return true;
}
// Potential problem case detected, apply workaround: -(int) -> ~(int) + 1.
// ~(int)
TIntermUnary *bitwiseNot = new TIntermUnary(EOpBitwiseNot, opr);
bitwiseNot->setLine(opr->getLine());
// Constant 1 (or 1u)
TConstantUnion *one = new TConstantUnion();
if (opr->getType().getBasicType() == EbtInt)
{
one->setIConst(1);
}
else
{
one->setUConst(1u);
}
TIntermConstantUnion *oneNode = new TIntermConstantUnion(one, opr->getType());
oneNode->getTypePointer()->setQualifier(EvqConst);
oneNode->setLine(opr->getLine());
// ~(int) + 1
TIntermBinary *add = new TIntermBinary(EOpAdd, bitwiseNot, oneNode);
add->setLine(opr->getLine());
queueReplacement(add, OriginalNode::IS_DROPPED);
mFound = true;
return false;
}
} // anonymous namespace
void RewriteUnaryMinusOperatorInt(TIntermNode *root)
{
Traverser::Apply(root);
}
} // namespace sh
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