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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.
//
// DeferGlobalInitializers is an AST traverser that moves global initializers into a function, and
// adds a function call to that function in the beginning of main().
// This enables initialization of globals with uniforms or non-constant globals, as allowed by
// the WebGL spec. Some initializers referencing non-constants may need to be unfolded into if
// statements in HLSL - this kind of steps should be done after DeferGlobalInitializers is run.
//
#include "compiler/translator/DeferGlobalInitializers.h"
#include "compiler/translator/IntermNode.h"
#include "compiler/translator/SymbolTable.h"
namespace
{
void SetInternalFunctionName(TIntermAggregate *functionNode, const char *name)
{
TString nameStr(name);
nameStr = TFunction::mangleName(nameStr);
TName nameObj(nameStr);
nameObj.setInternal(true);
functionNode->setNameObj(nameObj);
}
TIntermAggregate *CreateFunctionPrototypeNode(const char *name, const int functionId)
{
TIntermAggregate *functionNode = new TIntermAggregate(EOpPrototype);
SetInternalFunctionName(functionNode, name);
TType returnType(EbtVoid);
functionNode->setType(returnType);
functionNode->setFunctionId(functionId);
return functionNode;
}
TIntermAggregate *CreateFunctionDefinitionNode(const char *name,
TIntermAggregate *functionBody,
const int functionId)
{
TIntermAggregate *functionNode = new TIntermAggregate(EOpFunction);
TIntermAggregate *paramsNode = new TIntermAggregate(EOpParameters);
functionNode->getSequence()->push_back(paramsNode);
functionNode->getSequence()->push_back(functionBody);
SetInternalFunctionName(functionNode, name);
TType returnType(EbtVoid);
functionNode->setType(returnType);
functionNode->setFunctionId(functionId);
return functionNode;
}
TIntermAggregate *CreateFunctionCallNode(const char *name, const int functionId)
{
TIntermAggregate *functionNode = new TIntermAggregate(EOpFunctionCall);
functionNode->setUserDefined();
SetInternalFunctionName(functionNode, name);
TType returnType(EbtVoid);
functionNode->setType(returnType);
functionNode->setFunctionId(functionId);
return functionNode;
}
class DeferGlobalInitializersTraverser : public TIntermTraverser
{
public:
DeferGlobalInitializersTraverser();
bool visitBinary(Visit visit, TIntermBinary *node) override;
void insertInitFunction(TIntermNode *root);
private:
TIntermSequence mDeferredInitializers;
};
DeferGlobalInitializersTraverser::DeferGlobalInitializersTraverser()
: TIntermTraverser(true, false, false)
{
}
bool DeferGlobalInitializersTraverser::visitBinary(Visit visit, TIntermBinary *node)
{
if (node->getOp() == EOpInitialize)
{
TIntermSymbol *symbolNode = node->getLeft()->getAsSymbolNode();
ASSERT(symbolNode);
TIntermTyped *expression = node->getRight();
if (mInGlobalScope && (expression->getQualifier() != EvqConst ||
(expression->getAsConstantUnion() == nullptr &&
!expression->isConstructorWithOnlyConstantUnionParameters())))
{
// For variables which are not constant, defer their real initialization until
// after we initialize uniforms.
// Deferral is done also in any cases where the variable has not been constant folded,
// since otherwise there's a chance that HLSL output will generate extra statements
// from the initializer expression.
TIntermBinary *deferredInit = new TIntermBinary(EOpAssign);
deferredInit->setLeft(symbolNode->deepCopy());
deferredInit->setRight(node->getRight());
deferredInit->setType(node->getType());
mDeferredInitializers.push_back(deferredInit);
// Change const global to a regular global if its initialization is deferred.
// This can happen if ANGLE has not been able to fold the constant expression used
// as an initializer.
ASSERT(symbolNode->getQualifier() == EvqConst ||
symbolNode->getQualifier() == EvqGlobal);
if (symbolNode->getQualifier() == EvqConst)
{
// All of the siblings in the same declaration need to have consistent qualifiers.
auto *siblings = getParentNode()->getAsAggregate()->getSequence();
for (TIntermNode *siblingNode : *siblings)
{
TIntermBinary *siblingBinary = siblingNode->getAsBinaryNode();
if (siblingBinary)
{
ASSERT(siblingBinary->getOp() == EOpInitialize);
siblingBinary->getLeft()->getTypePointer()->setQualifier(EvqGlobal);
}
siblingNode->getAsTyped()->getTypePointer()->setQualifier(EvqGlobal);
}
// This node is one of the siblings.
ASSERT(symbolNode->getQualifier() == EvqGlobal);
}
// Remove the initializer from the global scope and just declare the global instead.
queueReplacement(node, symbolNode, OriginalNode::IS_DROPPED);
}
}
return false;
}
void DeferGlobalInitializersTraverser::insertInitFunction(TIntermNode *root)
{
if (mDeferredInitializers.empty())
{
return;
}
const int initFunctionId = TSymbolTable::nextUniqueId();
TIntermAggregate *rootAgg = root->getAsAggregate();
ASSERT(rootAgg != nullptr && rootAgg->getOp() == EOpSequence);
const char *functionName = "initializeDeferredGlobals";
// Add function prototype to the beginning of the shader
TIntermAggregate *functionPrototypeNode =
CreateFunctionPrototypeNode(functionName, initFunctionId);
rootAgg->getSequence()->insert(rootAgg->getSequence()->begin(), functionPrototypeNode);
// Add function definition to the end of the shader
TIntermAggregate *functionBodyNode = new TIntermAggregate(EOpSequence);
TIntermSequence *functionBody = functionBodyNode->getSequence();
for (const auto &deferredInit : mDeferredInitializers)
{
functionBody->push_back(deferredInit);
}
TIntermAggregate *functionDefinition =
CreateFunctionDefinitionNode(functionName, functionBodyNode, initFunctionId);
rootAgg->getSequence()->push_back(functionDefinition);
// Insert call into main function
for (TIntermNode *node : *rootAgg->getSequence())
{
TIntermAggregate *nodeAgg = node->getAsAggregate();
if (nodeAgg != nullptr && nodeAgg->getOp() == EOpFunction &&
TFunction::unmangleName(nodeAgg->getName()) == "main")
{
TIntermAggregate *functionCallNode =
CreateFunctionCallNode(functionName, initFunctionId);
TIntermNode *mainBody = nodeAgg->getSequence()->back();
TIntermAggregate *mainBodyAgg = mainBody->getAsAggregate();
ASSERT(mainBodyAgg != nullptr && mainBodyAgg->getOp() == EOpSequence);
mainBodyAgg->getSequence()->insert(mainBodyAgg->getSequence()->begin(),
functionCallNode);
}
}
}
} // namespace
void DeferGlobalInitializers(TIntermNode *root)
{
DeferGlobalInitializersTraverser traverser;
root->traverse(&traverser);
// Replace the initializers of the global variables.
traverser.updateTree();
// Add the function with initialization and the call to that.
traverser.insertInitFunction(root);
}
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