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//
// Copyright (c) 2002-2015 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.
//
// The ArrayReturnValueToOutParameter function changes return values of an array type to out parameters in
// function definitions, prototypes, and call sites.
#include "compiler/translator/ArrayReturnValueToOutParameter.h"
#include "compiler/translator/IntermNode.h"
namespace
{
void CopyAggregateChildren(TIntermAggregate *from, TIntermAggregate *to)
{
const TIntermSequence *fromSequence = from->getSequence();
for (size_t ii = 0; ii < fromSequence->size(); ++ii)
{
to->getSequence()->push_back(fromSequence->at(ii));
}
}
TIntermSymbol *CreateReturnValueSymbol(const TType &type)
{
TIntermSymbol *node = new TIntermSymbol(0, "angle_return", type);
node->setInternal(true);
return node;
}
TIntermSymbol *CreateReturnValueOutSymbol(const TType &type)
{
TType outType(type);
outType.setQualifier(EvqOut);
return CreateReturnValueSymbol(outType);
}
TIntermAggregate *CreateReplacementCall(TIntermAggregate *originalCall, TIntermTyped *returnValueTarget)
{
TIntermAggregate *replacementCall = new TIntermAggregate(EOpFunctionCall);
replacementCall->setType(TType(EbtVoid));
replacementCall->setUserDefined();
replacementCall->setNameObj(originalCall->getNameObj());
replacementCall->setFunctionId(originalCall->getFunctionId());
replacementCall->setLine(originalCall->getLine());
TIntermSequence *replacementParameters = replacementCall->getSequence();
TIntermSequence *originalParameters = originalCall->getSequence();
for (auto ¶m : *originalParameters)
{
replacementParameters->push_back(param);
}
replacementParameters->push_back(returnValueTarget);
return replacementCall;
}
class ArrayReturnValueToOutParameterTraverser : private TIntermTraverser
{
public:
static void apply(TIntermNode *root, unsigned int *temporaryIndex);
private:
ArrayReturnValueToOutParameterTraverser();
bool visitAggregate(Visit visit, TIntermAggregate *node) override;
bool visitBranch(Visit visit, TIntermBranch *node) override;
bool visitBinary(Visit visit, TIntermBinary *node) override;
bool mInFunctionWithArrayReturnValue;
};
void ArrayReturnValueToOutParameterTraverser::apply(TIntermNode *root, unsigned int *temporaryIndex)
{
ArrayReturnValueToOutParameterTraverser arrayReturnValueToOutParam;
arrayReturnValueToOutParam.useTemporaryIndex(temporaryIndex);
root->traverse(&arrayReturnValueToOutParam);
arrayReturnValueToOutParam.updateTree();
}
ArrayReturnValueToOutParameterTraverser::ArrayReturnValueToOutParameterTraverser()
: TIntermTraverser(true, false, true),
mInFunctionWithArrayReturnValue(false)
{
}
bool ArrayReturnValueToOutParameterTraverser::visitAggregate(Visit visit, TIntermAggregate *node)
{
if (visit == PreVisit)
{
if (node->isArray())
{
if (node->getOp() == EOpFunction)
{
// Replace the parameters child node of the function definition with another node
// that has the out parameter added.
// Also set the function to return void.
TIntermAggregate *params = node->getSequence()->front()->getAsAggregate();
ASSERT(params != nullptr && params->getOp() == EOpParameters);
TIntermAggregate *replacementParams = new TIntermAggregate;
replacementParams->setOp(EOpParameters);
CopyAggregateChildren(params, replacementParams);
replacementParams->getSequence()->push_back(CreateReturnValueOutSymbol(node->getType()));
replacementParams->setLine(params->getLine());
mReplacements.push_back(NodeUpdateEntry(node, params, replacementParams, false));
node->setType(TType(EbtVoid));
mInFunctionWithArrayReturnValue = true;
}
else if (node->getOp() == EOpPrototype)
{
// Replace the whole prototype node with another node that has the out parameter added.
TIntermAggregate *replacement = new TIntermAggregate;
replacement->setOp(EOpPrototype);
CopyAggregateChildren(node, replacement);
replacement->getSequence()->push_back(CreateReturnValueOutSymbol(node->getType()));
replacement->setUserDefined();
replacement->setNameObj(node->getNameObj());
replacement->setFunctionId(node->getFunctionId());
replacement->setLine(node->getLine());
replacement->setType(TType(EbtVoid));
mReplacements.push_back(NodeUpdateEntry(getParentNode(), node, replacement, false));
}
else if (node->getOp() == EOpFunctionCall)
{
// Handle call sites where the returned array is not assigned.
// Examples where f() is a function returning an array:
// 1. f();
// 2. another_array == f();
// 3. another_function(f());
// 4. return f();
// Cases 2 to 4 are already converted to simpler cases by SeparateExpressionsReturningArrays, so we
// only need to worry about the case where a function call returning an array forms an expression by
// itself.
TIntermAggregate *parentAgg = getParentNode()->getAsAggregate();
if (parentAgg != nullptr && parentAgg->getOp() == EOpSequence)
{
nextTemporaryIndex();
TIntermSequence replacements;
replacements.push_back(createTempDeclaration(node->getType()));
TIntermSymbol *returnSymbol = createTempSymbol(node->getType());
replacements.push_back(CreateReplacementCall(node, returnSymbol));
mMultiReplacements.push_back(NodeReplaceWithMultipleEntry(parentAgg, node, replacements));
}
return false;
}
}
}
else if (visit == PostVisit)
{
if (node->getOp() == EOpFunction)
{
mInFunctionWithArrayReturnValue = false;
}
}
return true;
}
bool ArrayReturnValueToOutParameterTraverser::visitBranch(Visit visit, TIntermBranch *node)
{
if (mInFunctionWithArrayReturnValue && node->getFlowOp() == EOpReturn)
{
// Instead of returning a value, assign to the out parameter and then return.
TIntermSequence replacements;
TIntermBinary *replacementAssignment = new TIntermBinary(EOpAssign);
TIntermTyped *expression = node->getExpression();
ASSERT(expression != nullptr);
replacementAssignment->setLeft(CreateReturnValueSymbol(expression->getType()));
replacementAssignment->setRight(node->getExpression());
replacementAssignment->setType(expression->getType());
replacementAssignment->setLine(expression->getLine());
replacements.push_back(replacementAssignment);
TIntermBranch *replacementBranch = new TIntermBranch(EOpReturn, nullptr);
replacementBranch->setLine(node->getLine());
replacements.push_back(replacementBranch);
mMultiReplacements.push_back(NodeReplaceWithMultipleEntry(getParentNode()->getAsAggregate(), node, replacements));
}
return false;
}
bool ArrayReturnValueToOutParameterTraverser::visitBinary(Visit visit, TIntermBinary *node)
{
if (node->getOp() == EOpAssign && node->getLeft()->isArray())
{
TIntermAggregate *rightAgg = node->getRight()->getAsAggregate();
if (rightAgg != nullptr && rightAgg->getOp() == EOpFunctionCall && rightAgg->isUserDefined())
{
TIntermAggregate *replacementCall = CreateReplacementCall(rightAgg, node->getLeft());
mReplacements.push_back(NodeUpdateEntry(getParentNode(), node, replacementCall, false));
}
}
return false;
}
} // namespace
void ArrayReturnValueToOutParameter(TIntermNode *root, unsigned int *temporaryIndex)
{
ArrayReturnValueToOutParameterTraverser::apply(root, temporaryIndex);
}
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