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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.
//
// RunAtTheEndOfShader.cpp: Add code to be run at the end of the shader. In case main() contains a
// return statement, this is done by replacing the main() function with another function that calls
// the old main, like this:
//
// void main() { body }
// =>
// void main0() { body }
// void main()
// {
// main0();
// codeToRun
// }
//
// This way the code will get run even if the return statement inside main is executed.
//
#include "compiler/translator/RunAtTheEndOfShader.h"
#include "compiler/translator/FindMain.h"
#include "compiler/translator/IntermNode.h"
#include "compiler/translator/IntermNode_util.h"
#include "compiler/translator/IntermTraverse.h"
#include "compiler/translator/SymbolTable.h"
namespace sh
{
namespace
{
class ContainsReturnTraverser : public TIntermTraverser
{
public:
ContainsReturnTraverser() : TIntermTraverser(true, false, false), mContainsReturn(false) {}
bool visitBranch(Visit visit, TIntermBranch *node) override
{
if (node->getFlowOp() == EOpReturn)
{
mContainsReturn = true;
}
return false;
}
bool containsReturn() { return mContainsReturn; }
private:
bool mContainsReturn;
};
bool ContainsReturn(TIntermNode *node)
{
ContainsReturnTraverser traverser;
node->traverse(&traverser);
return traverser.containsReturn();
}
void WrapMainAndAppend(TIntermBlock *root,
TIntermFunctionDefinition *main,
TIntermNode *codeToRun,
TSymbolTable *symbolTable)
{
// Replace main() with main0() with the same body.
TSymbolUniqueId oldMainId(symbolTable);
std::stringstream oldMainName;
oldMainName << "main" << oldMainId.get();
TIntermFunctionDefinition *oldMain = CreateInternalFunctionDefinitionNode(
TType(EbtVoid), oldMainName.str().c_str(), main->getBody(), oldMainId);
bool replaced = root->replaceChildNode(main, oldMain);
ASSERT(replaced);
// void main()
TIntermFunctionPrototype *newMainProto = new TIntermFunctionPrototype(
TType(EbtVoid), main->getFunctionPrototype()->getFunctionSymbolInfo()->getId());
newMainProto->getFunctionSymbolInfo()->setName("main");
// {
// main0();
// codeToRun
// }
TIntermBlock *newMainBody = new TIntermBlock();
TIntermAggregate *oldMainCall = CreateInternalFunctionCallNode(
TType(EbtVoid), oldMainName.str().c_str(), oldMainId, new TIntermSequence());
newMainBody->appendStatement(oldMainCall);
newMainBody->appendStatement(codeToRun);
// Add the new main() to the root node.
TIntermFunctionDefinition *newMain = new TIntermFunctionDefinition(newMainProto, newMainBody);
root->appendStatement(newMain);
}
} // anonymous namespace
void RunAtTheEndOfShader(TIntermBlock *root, TIntermNode *codeToRun, TSymbolTable *symbolTable)
{
TIntermFunctionDefinition *main = FindMain(root);
if (!ContainsReturn(main))
{
main->getBody()->appendStatement(codeToRun);
return;
}
WrapMainAndAppend(root, main, codeToRun, symbolTable);
}
} // namespace sh
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