ValidateBarrierFunctionCall.cpp

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//

// Copyright 2020 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.

//

// ValidateBarrierFunctionCalls:

//   Runs compilation checks related to the "barrier built-in function.

#include "compiler/translator/ValidateBarrierFunctionCall.h"

#include "compiler/translator/Diagnostics.h"

#include "compiler/translator/SymbolTable.h"

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

namespace sh

namespace

class Traverser : public TIntermTraverser

  public:

    Traverser(TDiagnostics *diagnostics)

        : TIntermTraverser(true, false, true), mDiagnostics(diagnostics)

{}

    bool visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *node) override

        if (!node->getFunction()->isMain())

            return false;

        mInMain = visit == PreVisit;

        return true;

    bool visitBranch(Visit visit, TIntermBranch *branch) override

        if (branch->getFlowOp() == EOpReturn)

            mSeenReturn = true;

        return true;

    bool visitAggregate(Visit visit, TIntermAggregate *node) override

        if (node->getOp() != EOpBarrierTCS)

            return true;

        if (mSeenReturn)

            mDiagnostics->error(node->getLine(),

                                "barrier() may not be called at any point after a return statement "

                                "in the function main().",

                                "barrier");

            mValid = false;

            return false;

        // TODO(anglebug.com/5557): Determine if we should check loops as well.

        if (mBranchCount > 0)

            mDiagnostics->error(

                node->getLine(),

                "barrier() may not be called in potentially divergent flow control.", "barrier");

            mValid = false;

            return false;

        return true;

    bool visitIfElse(Visit visit, TIntermIfElse *node) override

        mBranchCount += ((visit == PreVisit) ? 1 : -1);

        return true;

    bool valid() const { return mValid; }

  private:

    TDiagnostics *mDiagnostics = nullptr;

    bool mInMain               = false;

    bool mSeenReturn           = false;

    bool mValid                = true;

    uint32_t mBranchCount      = 0;

};

}  // anonymous namespace

bool ValidateBarrierFunctionCall(TIntermBlock *root, TDiagnostics *diagnostics)

    Traverser traverser(diagnostics);

    root->traverse(&traverser);

    return traverser.valid();

}  // namespace sh