DeferGlobalInitializers.cpp

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Author : Shahbaz Youssefi
Date : 2019-08-19 16:32:13
Hash : 472c74c6
Message : Translator: Allow tree validation in children of TCompiler This is to be able to perform validation inside TranslatorVulkan, even if it's through ASSERTs. Additionally, every transformation is changed such that they do their validation themselves. TIntermTraverser::updateTree() performs the validation, which indirectly validates many of three tree transformations. Some of the more ancient transformations that don't use this function directly call TCompiler::validateAST. Bug: angleproject:2733 Change-Id: Ie4af029d34e053c5ad1dc8c2c2568eecd625d344 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1761149 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@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/Compiler.h"
#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

bool DeferGlobalInitializers(TCompiler *compiler,
                             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());
        if (!ReplaceVariable(compiler, root, var, replacement))
        {
            return false;
        }
    }

    return true;
}

}  // 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