DeferGlobalInitializers.cpp

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Author : Olli Etuaho
Date : 2016-04-15 15:11:24
Hash : d4f4c11b
Message : Fix deferring global array initialization The initial implementation of DeferGlobalInitializers did not take HLSL corner cases into account. In particular, in case there was a const-qualified array variable with an initializer that contained elements that weren't constant folded, initialization would not be deferred and the global scope of HLSL output would contain a call to angle_construct_into_*(). On the other hand, deferring global initializers was also done in cases where it wasn't necessary. Initializers of non-const qualified array variables that could be written as HLSL literals by HLSL output were unnecessarily deferred. This patch fixes both of these issues: Now all global initializers are potential candidates for deferral instead of just those where the symbol has the EvqGlobal qualifier, and initializers that are constructors taking only constant unions as parameters are not unnecessarily deferred. BUG=angleproject:1205 BUG=541551 TEST=angle_end2end_tests Change-Id: I4027059e0e5f39c8a5a48b5c97a3fceaac6b6f8a Reviewed-on: https://chromium-review.googlesource.com/339201 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>

src/compiler/translator/DeferGlobalInitializers.cpp

//
// 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.
            mReplacements.push_back(NodeUpdateEntry(getParentNode(), node, symbolNode, false));
        }
    }
    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);
}

kc3-lang/angle/src/compiler/translator/DeferGlobalInitializers.cpp

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kc3-lang/angle /src/compiler/translator/DeferGlobalInitializers.cpp