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//
// Copyright (c) 2017 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.
//
// RemoveArrayLengthMethod.cpp:
// Fold array length expressions, including cases where the "this" node has side effects.
// Example:
// int i = (a = b).length();
// int j = (func()).length();
// becomes:
// (a = b);
// int i = <constant array length>;
// func();
// int j = <constant array length>;
//
// Must be run after SplitSequenceOperator, SimplifyLoopConditions and SeparateDeclarations steps
// have been done to expressions containing calls of the array length method.
//
// Does nothing to length method calls done on runtime-sized arrays.
#include "compiler/translator/RemoveArrayLengthMethod.h"
#include "compiler/translator/IntermNode.h"
#include "compiler/translator/IntermTraverse.h"
namespace sh
{
namespace
{
class RemoveArrayLengthTraverser : public TIntermTraverser
{
public:
RemoveArrayLengthTraverser() : TIntermTraverser(true, false, false), mFoundArrayLength(false) {}
bool visitUnary(Visit visit, TIntermUnary *node) override;
void nextIteration() { mFoundArrayLength = false; }
bool foundArrayLength() const { return mFoundArrayLength; }
private:
bool mFoundArrayLength;
};
bool RemoveArrayLengthTraverser::visitUnary(Visit visit, TIntermUnary *node)
{
// The only case where we leave array length() in place is for runtime-sized arrays.
if (node->getOp() == EOpArrayLength && !node->getOperand()->getType().isUnsizedArray())
{
mFoundArrayLength = true;
if (!node->getOperand()->hasSideEffects())
{
queueReplacement(node->fold(nullptr), OriginalNode::IS_DROPPED);
return false;
}
insertStatementInParentBlock(node->getOperand()->deepCopy());
TConstantUnion *constArray = new TConstantUnion[1];
constArray->setIConst(node->getOperand()->getOutermostArraySize());
queueReplacement(new TIntermConstantUnion(constArray, node->getType()),
OriginalNode::IS_DROPPED);
return false;
}
return true;
}
} // anonymous namespace
void RemoveArrayLengthMethod(TIntermBlock *root)
{
RemoveArrayLengthTraverser traverser;
do
{
traverser.nextIteration();
root->traverse(&traverser);
if (traverser.foundArrayLength())
traverser.updateTree();
} while (traverser.foundArrayLength());
}
} // namespace sh
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