DeferGlobalInitializers.cpp

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Author : Stuart Morgan
Date : 2019-08-14 12:25:12
Hash : 9d737966
Message : Standardize copyright notices to project style For all "ANGLE Project" copyrights, standardize to the format specified by the style guide. Changes: - "Copyright (c)" and "Copyright(c)" changed to just "Copyright". - Removed the second half of date ranges ("Y1Y1-Y2Y2"->"Y1Y1"). - Fixed a small number of files that had no copyright date using the initial commit year from the version control history. - Fixed one instance of copyright being "The ANGLE Project" rather than "The ANGLE Project Authors" These changes are applied both to the copyright of source file, and where applicable to copyright statements that are generated by templates. BUG=angleproject:3811 Change-Id: I973dd65e4ef9deeba232d5be74c768256a0eb2e5 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1754397 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>

src/compiler/translator/tree_ops/DeferGlobalInitializers.cpp

//
// Copyright 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 separate
// function that is called 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. Note that it's important that the function definition
// is at the end of the shader, as some globals may be declared after main().
//
// It can also initialize all uninitialized globals.
//

#include "compiler/translator/tree_ops/DeferGlobalInitializers.h"

#include <vector>

#include "compiler/translator/IntermNode.h"
#include "compiler/translator/StaticType.h"
#include "compiler/translator/SymbolTable.h"
#include "compiler/translator/tree_ops/InitializeVariables.h"
#include "compiler/translator/tree_util/FindMain.h"
#include "compiler/translator/tree_util/IntermNode_util.h"
#include "compiler/translator/tree_util/ReplaceVariable.h"

namespace sh
{

namespace
{

constexpr const ImmutableString kInitGlobalsString("initGlobals");

void GetDeferredInitializers(TIntermDeclaration *declaration,
                             bool initializeUninitializedGlobals,
                             bool canUseLoopsToInitialize,
                             bool highPrecisionSupported,
                             TIntermSequence *deferredInitializersOut,
                             std::vector<const TVariable *> *variablesToReplaceOut,
                             TSymbolTable *symbolTable)
{
    // SeparateDeclarations should have already been run.
    ASSERT(declaration->getSequence()->size() == 1);

    TIntermNode *declarator = declaration->getSequence()->back();
    TIntermBinary *init     = declarator->getAsBinaryNode();
    if (init)
    {
        TIntermSymbol *symbolNode = init->getLeft()->getAsSymbolNode();
        ASSERT(symbolNode);
        TIntermTyped *expression = init->getRight();

        if (expression->getQualifier() != EvqConst || !expression->hasConstantValue())
        {
            // 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 can not be converted to a
            // constant union, since otherwise there's a chance that HLSL output will generate extra
            // statements from the initializer expression.

            // 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)
            {
                variablesToReplaceOut->push_back(&symbolNode->variable());
            }

            TIntermBinary *deferredInit =
                new TIntermBinary(EOpAssign, symbolNode->deepCopy(), init->getRight());
            deferredInitializersOut->push_back(deferredInit);

            // Remove the initializer from the global scope and just declare the global instead.
            declaration->replaceChildNode(init, symbolNode);
        }
    }
    else if (initializeUninitializedGlobals)
    {
        TIntermSymbol *symbolNode = declarator->getAsSymbolNode();
        ASSERT(symbolNode);

        // Ignore ANGLE internal variables and nameless declarations.
        if (symbolNode->variable().symbolType() == SymbolType::AngleInternal ||
            symbolNode->variable().symbolType() == SymbolType::Empty)
            return;

        if (symbolNode->getQualifier() == EvqGlobal)
        {
            TIntermSequence *initCode = CreateInitCode(symbolNode, canUseLoopsToInitialize,
                                                       highPrecisionSupported, symbolTable);
            deferredInitializersOut->insert(deferredInitializersOut->end(), initCode->begin(),
                                            initCode->end());
        }
    }
}

void InsertInitCallToMain(TIntermBlock *root,
                          TIntermSequence *deferredInitializers,
                          TSymbolTable *symbolTable)
{
    TIntermBlock *initGlobalsBlock = new TIntermBlock();
    initGlobalsBlock->getSequence()->swap(*deferredInitializers);

    TFunction *initGlobalsFunction =
        new TFunction(symbolTable, kInitGlobalsString, SymbolType::AngleInternal,
                      StaticType::GetBasic<EbtVoid>(), false);

    TIntermFunctionPrototype *initGlobalsFunctionPrototype =
        CreateInternalFunctionPrototypeNode(*initGlobalsFunction);
    root->getSequence()->insert(root->getSequence()->begin(), initGlobalsFunctionPrototype);
    TIntermFunctionDefinition *initGlobalsFunctionDefinition =
        CreateInternalFunctionDefinitionNode(*initGlobalsFunction, initGlobalsBlock);
    root->appendStatement(initGlobalsFunctionDefinition);

    TIntermAggregate *initGlobalsCall =
        TIntermAggregate::CreateFunctionCall(*initGlobalsFunction, new TIntermSequence());

    TIntermBlock *mainBody = FindMainBody(root);
    mainBody->getSequence()->insert(mainBody->getSequence()->begin(), initGlobalsCall);
}

}  // namespace

void DeferGlobalInitializers(TIntermBlock *root,
                             bool initializeUninitializedGlobals,
                             bool canUseLoopsToInitialize,
                             bool highPrecisionSupported,
                             TSymbolTable *symbolTable)
{
    TIntermSequence *deferredInitializers = new TIntermSequence();
    std::vector<const TVariable *> variablesToReplace;

    // Loop over all global statements and process the declarations. This is simpler than using a
    // traverser.
    for (TIntermNode *statement : *root->getSequence())
    {
        TIntermDeclaration *declaration = statement->getAsDeclarationNode();
        if (declaration)
        {
            GetDeferredInitializers(declaration, initializeUninitializedGlobals,
                                    canUseLoopsToInitialize, highPrecisionSupported,
                                    deferredInitializers, &variablesToReplace, symbolTable);
        }
    }

    // Add the function with initialization and the call to that.
    if (!deferredInitializers->empty())
    {
        InsertInitCallToMain(root, deferredInitializers, symbolTable);
    }

    // Replace constant variables with non-constant global variables.
    for (const TVariable *var : variablesToReplace)
    {
        TType *replacementType = new TType(var->getType());
        replacementType->setQualifier(EvqGlobal);
        TVariable *replacement =
            new TVariable(symbolTable, var->name(), replacementType, var->symbolType());
        ReplaceVariable(root, var, replacement);
    }
}

}  // namespace sh

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

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