RegenerateStructNames.cpp

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//

// Copyright 2002 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.

//

#include "compiler/translator/tree_ops/gl/RegenerateStructNames.h"

#include "common/debug.h"

#include "compiler/translator/Compiler.h"

#include "compiler/translator/ImmutableStringBuilder.h"

#include "compiler/translator/SymbolTable.h"

#include "compiler/translator/tree_util/IntermTraverse.h"

#include <set>

namespace sh

namespace

constexpr const ImmutableString kPrefix("_webgl_struct_");

}  // anonymous namespace

class RegenerateStructNamesTraverser : public TIntermTraverser

  public:

    RegenerateStructNamesTraverser(TSymbolTable *symbolTable)

        : TIntermTraverser(true, false, false, symbolTable), mScopeDepth(0)

{}

  protected:

    void visitSymbol(TIntermSymbol *) override;

    bool visitBlock(Visit, TIntermBlock *block) override;

  private:

    // Indicating the depth of the current scope.

    // The global scope is 1.

    int mScopeDepth;

    // If a struct is declared globally, push its ID in this set.

    std::set<int> mDeclaredGlobalStructs;

};

void RegenerateStructNamesTraverser::visitSymbol(TIntermSymbol *symbol)

    ASSERT(symbol);

    const TType &type          = symbol->getType();

    const TStructure *userType = type.getStruct();

    if (!userType)

        return;

    if (userType->symbolType() == SymbolType::BuiltIn ||

        userType->symbolType() == SymbolType::Empty)

        // Built-in struct or nameless struct, do not touch it.

        return;

    int uniqueId = userType->uniqueId().get();

    ASSERT(mScopeDepth > 0);

    if (mScopeDepth == 1)

        // If a struct is defined at global scope, we don't map its name.

        // This is because at global level, the struct might be used to

        // declare a uniform, so the same name needs to stay the same for

        // vertex/fragment shaders. However, our mapping uses internal ID,

        // which will be different for the same struct in vertex/fragment

        // shaders.

        // This is OK because names for any structs defined in other scopes

        // will begin with "_webgl", which is reserved. So there will be

        // no conflicts among unmapped struct names from global scope and

        // mapped struct names from other scopes.

        // However, we need to keep track of these global structs, so if a

        // variable is used in a local scope, we don't try to modify the

        // struct name through that variable.

        mDeclaredGlobalStructs.insert(uniqueId);

        return;

    if (mDeclaredGlobalStructs.count(uniqueId) > 0)

        return;

    // Map {name} to _webgl_struct_{uniqueId}_{name}.

    if (userType->name().beginsWith(kPrefix))

        // The name has already been regenerated.

        return;

    ImmutableStringBuilder tmp(kPrefix.length() + sizeof(uniqueId) * 2u + 1u +

                               userType->name().length());

    tmp << kPrefix;

    tmp.appendHex(uniqueId);

    tmp << '_' << userType->name();

    // TODO(oetuaho): Add another mechanism to change symbol names so that the const_cast is not

    // needed.

    const_cast<TStructure *>(userType)->setName(tmp);

bool RegenerateStructNamesTraverser::visitBlock(Visit, TIntermBlock *block)

    ++mScopeDepth;

    TIntermSequence &sequence = *(block->getSequence());

    for (TIntermNode *node : sequence)

        node->traverse(this);

    --mScopeDepth;

    return false;

bool RegenerateStructNames(TCompiler *compiler, TIntermBlock *root, TSymbolTable *symbolTable)

    RegenerateStructNamesTraverser traverser(symbolTable);

    root->traverse(&traverser);

    return compiler->validateAST(root);

}  // namespace sh