RewriteUnaryMinusOperatorInt.cpp

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//

// 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.

//

// Implementation of evaluating unary integer variable bug workaround.

// See header for more info.

#include "compiler/translator/tree_ops/d3d/RewriteUnaryMinusOperatorInt.h"

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

namespace sh

namespace

class Traverser : public TIntermTraverser

  public:

    [[nodiscard]] static bool Apply(TCompiler *compiler, TIntermNode *root);

  private:

    Traverser();

    bool visitUnary(Visit visit, TIntermUnary *node) override;

    void nextIteration();

    bool mFound = false;

};

// static

bool Traverser::Apply(TCompiler *compiler, TIntermNode *root)

    Traverser traverser;

do

        traverser.nextIteration();

        root->traverse(&traverser);

        if (traverser.mFound)

            if (!traverser.updateTree(compiler, root))

                return false;

    } while (traverser.mFound);

    return true;

Traverser::Traverser() : TIntermTraverser(true, false, false) {}

void Traverser::nextIteration()

    mFound = false;

bool Traverser::visitUnary(Visit visit, TIntermUnary *node)

    if (mFound)

        return false;

    // Decide if the current unary operator is unary minus.

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

        return true;

    // Decide if the current operand is an integer variable.

    TIntermTyped *opr = node->getOperand();

    if (!opr->getType().isScalarInt())

        return true;

    // Potential problem case detected, apply workaround: -(int) -> ~(int) + 1.

    // ~(int)

    TIntermUnary *bitwiseNot = new TIntermUnary(EOpBitwiseNot, opr, nullptr);

    bitwiseNot->setLine(opr->getLine());

    // Constant 1 (or 1u)

    TConstantUnion *one = new TConstantUnion();

    if (opr->getType().getBasicType() == EbtInt)

        one->setIConst(1);

    else

        one->setUConst(1u);

    TType *oneType = new TType(opr->getType());

    oneType->setQualifier(EvqConst);

    TIntermConstantUnion *oneNode = new TIntermConstantUnion(one, *oneType);

    oneNode->setLine(opr->getLine());

    // ~(int) + 1

    TIntermBinary *add = new TIntermBinary(EOpAdd, bitwiseNot, oneNode);

    add->setLine(opr->getLine());

    queueReplacement(add, OriginalNode::IS_DROPPED);

    mFound = true;

    return false;

}  // anonymous namespace

bool RewriteUnaryMinusOperatorInt(TCompiler *compiler, TIntermNode *root)

    return Traverser::Apply(compiler, root);

}  // namespace sh