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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 <map>
#include "compiler/translator/IntermTraverse.h"
#include "compiler/translator/SymbolTable.h"
namespace sh
{
namespace
{
void CopyAggregateChildren(TIntermAggregateBase *from, TIntermAggregateBase *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 TSymbolUniqueId &id, const TType &type)
{
TIntermSymbol *node = new TIntermSymbol(id, "angle_return", type);
node->setInternal(true);
node->getTypePointer()->setQualifier(EvqOut);
return node;
}
TIntermAggregate *CreateReplacementCall(TIntermAggregate *originalCall,
TIntermTyped *returnValueTarget)
{
TIntermSequence *replacementArguments = new TIntermSequence();
TIntermSequence *originalArguments = originalCall->getSequence();
for (auto &arg : *originalArguments)
{
replacementArguments->push_back(arg);
}
replacementArguments->push_back(returnValueTarget);
TIntermAggregate *replacementCall = TIntermAggregate::CreateFunctionCall(
TType(EbtVoid), originalCall->getFunctionSymbolInfo()->getId(),
originalCall->getFunctionSymbolInfo()->getNameObj(), replacementArguments);
replacementCall->setLine(originalCall->getLine());
return replacementCall;
}
class ArrayReturnValueToOutParameterTraverser : private TIntermTraverser
{
public:
static void apply(TIntermNode *root, TSymbolTable *symbolTable);
private:
ArrayReturnValueToOutParameterTraverser(TSymbolTable *symbolTable);
bool visitFunctionPrototype(Visit visit, TIntermFunctionPrototype *node) override;
bool visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *node) override;
bool visitAggregate(Visit visit, TIntermAggregate *node) override;
bool visitBranch(Visit visit, TIntermBranch *node) override;
bool visitBinary(Visit visit, TIntermBinary *node) override;
// Set when traversal is inside a function with array return value.
TIntermFunctionDefinition *mFunctionWithArrayReturnValue;
// Map from function symbol ids to array return value ids.
std::map<int, TSymbolUniqueId *> mReturnValueIds;
};
void ArrayReturnValueToOutParameterTraverser::apply(TIntermNode *root, TSymbolTable *symbolTable)
{
ArrayReturnValueToOutParameterTraverser arrayReturnValueToOutParam(symbolTable);
root->traverse(&arrayReturnValueToOutParam);
arrayReturnValueToOutParam.updateTree();
}
ArrayReturnValueToOutParameterTraverser::ArrayReturnValueToOutParameterTraverser(
TSymbolTable *symbolTable)
: TIntermTraverser(true, false, true, symbolTable), mFunctionWithArrayReturnValue(nullptr)
{
}
bool ArrayReturnValueToOutParameterTraverser::visitFunctionDefinition(
Visit visit,
TIntermFunctionDefinition *node)
{
if (node->getFunctionPrototype()->isArray() && visit == PreVisit)
{
// Replacing the function header is done on visitFunctionPrototype().
mFunctionWithArrayReturnValue = node;
}
if (visit == PostVisit)
{
mFunctionWithArrayReturnValue = nullptr;
}
return true;
}
bool ArrayReturnValueToOutParameterTraverser::visitFunctionPrototype(Visit visit,
TIntermFunctionPrototype *node)
{
if (visit == PreVisit && node->isArray())
{
// Replace the whole prototype node with another node that has the out parameter
// added. Also set the function to return void.
TIntermFunctionPrototype *replacement =
new TIntermFunctionPrototype(TType(EbtVoid), node->getFunctionSymbolInfo()->getId());
CopyAggregateChildren(node, replacement);
const TSymbolUniqueId &functionId = node->getFunctionSymbolInfo()->getId();
if (mReturnValueIds.find(functionId.get()) == mReturnValueIds.end())
{
mReturnValueIds[functionId.get()] = new TSymbolUniqueId(mSymbolTable);
}
replacement->getSequence()->push_back(
CreateReturnValueSymbol(*mReturnValueIds[functionId.get()], node->getType()));
*replacement->getFunctionSymbolInfo() = *node->getFunctionSymbolInfo();
replacement->setLine(node->getLine());
queueReplacement(replacement, OriginalNode::IS_DROPPED);
}
return false;
}
bool ArrayReturnValueToOutParameterTraverser::visitAggregate(Visit visit, TIntermAggregate *node)
{
ASSERT(!node->isArray() || node->getOp() != EOpCallInternalRawFunction);
if (visit == PreVisit && node->isArray() && node->getOp() == EOpCallFunctionInAST)
{
// 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.
TIntermBlock *parentBlock = getParentNode()->getAsBlock();
if (parentBlock)
{
nextTemporaryId();
TIntermSequence replacements;
replacements.push_back(createTempDeclaration(node->getType()));
TIntermSymbol *returnSymbol = createTempSymbol(node->getType());
replacements.push_back(CreateReplacementCall(node, returnSymbol));
mMultiReplacements.push_back(
NodeReplaceWithMultipleEntry(parentBlock, node, replacements));
}
return false;
}
return true;
}
bool ArrayReturnValueToOutParameterTraverser::visitBranch(Visit visit, TIntermBranch *node)
{
if (mFunctionWithArrayReturnValue && node->getFlowOp() == EOpReturn)
{
// Instead of returning a value, assign to the out parameter and then return.
TIntermSequence replacements;
TIntermTyped *expression = node->getExpression();
ASSERT(expression != nullptr);
const TSymbolUniqueId &functionId =
mFunctionWithArrayReturnValue->getFunctionSymbolInfo()->getId();
ASSERT(mReturnValueIds.find(functionId.get()) != mReturnValueIds.end());
const TSymbolUniqueId &returnValueId = *mReturnValueIds[functionId.get()];
TIntermSymbol *returnValueSymbol =
CreateReturnValueSymbol(returnValueId, expression->getType());
TIntermBinary *replacementAssignment =
new TIntermBinary(EOpAssign, returnValueSymbol, expression);
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()->getAsBlock(), node, replacements));
}
return false;
}
bool ArrayReturnValueToOutParameterTraverser::visitBinary(Visit visit, TIntermBinary *node)
{
if (node->getOp() == EOpAssign && node->getLeft()->isArray())
{
TIntermAggregate *rightAgg = node->getRight()->getAsAggregate();
ASSERT(rightAgg == nullptr || rightAgg->getOp() != EOpCallInternalRawFunction);
if (rightAgg != nullptr && rightAgg->getOp() == EOpCallFunctionInAST)
{
TIntermAggregate *replacementCall = CreateReplacementCall(rightAgg, node->getLeft());
queueReplacement(replacementCall, OriginalNode::IS_DROPPED);
}
}
return false;
}
} // namespace
void ArrayReturnValueToOutParameter(TIntermNode *root, TSymbolTable *symbolTable)
{
ArrayReturnValueToOutParameterTraverser::apply(root, symbolTable);
}
} // namespace sh
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