src/compiler/translator/IntermNode.cpp

//
// Copyright (c) 2002-2014 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.
//

//
// Build the intermediate representation.
//

#include <float.h>
#include <limits.h>
#include <math.h>
#include <stdlib.h>
#include <algorithm>
#include <vector>

#include "common/mathutil.h"
#include "common/matrix_utils.h"
#include "compiler/translator/Diagnostics.h"
#include "compiler/translator/HashNames.h"
#include "compiler/translator/IntermNode.h"
#include "compiler/translator/SymbolTable.h"
#include "compiler/translator/util.h"

namespace
{

const float kPi = 3.14159265358979323846f;
const float kDegreesToRadiansMultiplier = kPi / 180.0f;
const float kRadiansToDegreesMultiplier = 180.0f / kPi;

TPrecision GetHigherPrecision(TPrecision left, TPrecision right)
{
    return left > right ? left : right;
}

TConstantUnion *Vectorize(const TConstantUnion &constant, size_t size)
{
    TConstantUnion *constUnion = new TConstantUnion[size];
    for (unsigned int i = 0; i < size; ++i)
        constUnion[i] = constant;

    return constUnion;
}

void UndefinedConstantFoldingError(const TSourceLoc &loc,
                                   TOperator op,
                                   TBasicType basicType,
                                   TDiagnostics *diagnostics,
                                   TConstantUnion *result)
{
    diagnostics->warning(loc, "operation result is undefined for the values passed in",
                         GetOperatorString(op), "");

    switch (basicType)
    {
      case EbtFloat :
        result->setFConst(0.0f);
        break;
      case EbtInt:
        result->setIConst(0);
        break;
      case EbtUInt:
        result->setUConst(0u);
        break;
      case EbtBool:
        result->setBConst(false);
        break;
      default:
        break;
    }
}

float VectorLength(const TConstantUnion *paramArray, size_t paramArraySize)
{
    float result = 0.0f;
    for (size_t i = 0; i < paramArraySize; i++)
    {
        float f = paramArray[i].getFConst();
        result += f * f;
    }
    return sqrtf(result);
}

float VectorDotProduct(const TConstantUnion *paramArray1,
                       const TConstantUnion *paramArray2,
                       size_t paramArraySize)
{
    float result = 0.0f;
    for (size_t i = 0; i < paramArraySize; i++)
        result += paramArray1[i].getFConst() * paramArray2[i].getFConst();
    return result;
}

TIntermTyped *CreateFoldedNode(TConstantUnion *constArray,
                               const TIntermTyped *originalNode,
                               TQualifier qualifier)
{
    if (constArray == nullptr)
    {
        return nullptr;
    }
    TIntermTyped *folded = new TIntermConstantUnion(constArray, originalNode->getType());
    folded->getTypePointer()->setQualifier(qualifier);
    folded->setLine(originalNode->getLine());
    return folded;
}

angle::Matrix<float> GetMatrix(const TConstantUnion *paramArray,
                               const unsigned int &rows,
                               const unsigned int &cols)
{
    std::vector<float> elements;
    for (size_t i = 0; i < rows * cols; i++)
        elements.push_back(paramArray[i].getFConst());
    // Transpose is used since the Matrix constructor expects arguments in row-major order,
    // whereas the paramArray is in column-major order. Rows/cols parameters are also flipped below
    // so that the created matrix will have the expected dimensions after the transpose.
    return angle::Matrix<float>(elements, cols, rows).transpose();
}

angle::Matrix<float> GetMatrix(const TConstantUnion *paramArray, const unsigned int &size)
{
    std::vector<float> elements;
    for (size_t i = 0; i < size * size; i++)
        elements.push_back(paramArray[i].getFConst());
    // Transpose is used since the Matrix constructor expects arguments in row-major order,
    // whereas the paramArray is in column-major order.
    return angle::Matrix<float>(elements, size).transpose();
}

void SetUnionArrayFromMatrix(const angle::Matrix<float> &m, TConstantUnion *resultArray)
{
    // Transpose is used since the input Matrix is in row-major order,
    // whereas the actual result should be in column-major order.
    angle::Matrix<float> result = m.transpose();
    std::vector<float> resultElements = result.elements();
    for (size_t i = 0; i < resultElements.size(); i++)
        resultArray[i].setFConst(resultElements[i]);
}

}  // namespace anonymous


////////////////////////////////////////////////////////////////
//
// Member functions of the nodes used for building the tree.
//
////////////////////////////////////////////////////////////////

void TIntermTyped::setTypePreservePrecision(const TType &t)
{
    TPrecision precision = getPrecision();
    mType = t;
    ASSERT(mType.getBasicType() != EbtBool || precision == EbpUndefined);
    mType.setPrecision(precision);
}

#define REPLACE_IF_IS(node, type, original, replacement) \
    if (node == original) { \
        node = static_cast<type *>(replacement); \
        return true; \
    }

bool TIntermLoop::replaceChildNode(
    TIntermNode *original, TIntermNode *replacement)
{
    ASSERT(original != nullptr);  // This risks replacing multiple children.
    REPLACE_IF_IS(mInit, TIntermNode, original, replacement);
    REPLACE_IF_IS(mCond, TIntermTyped, original, replacement);
    REPLACE_IF_IS(mExpr, TIntermTyped, original, replacement);
    REPLACE_IF_IS(mBody, TIntermAggregate, original, replacement);
    return false;
}

bool TIntermBranch::replaceChildNode(
    TIntermNode *original, TIntermNode *replacement)
{
    REPLACE_IF_IS(mExpression, TIntermTyped, original, replacement);
    return false;
}

bool TIntermBinary::replaceChildNode(
    TIntermNode *original, TIntermNode *replacement)
{
    REPLACE_IF_IS(mLeft, TIntermTyped, original, replacement);
    REPLACE_IF_IS(mRight, TIntermTyped, original, replacement);
    return false;
}

bool TIntermUnary::replaceChildNode(
    TIntermNode *original, TIntermNode *replacement)
{
    REPLACE_IF_IS(mOperand, TIntermTyped, original, replacement);
    return false;
}

bool TIntermAggregate::replaceChildNode(
    TIntermNode *original, TIntermNode *replacement)
{
    for (size_t ii = 0; ii < mSequence.size(); ++ii)
    {
        REPLACE_IF_IS(mSequence[ii], TIntermNode, original, replacement);
    }
    return false;
}

bool TIntermAggregate::replaceChildNodeWithMultiple(TIntermNode *original, TIntermSequence replacements)
{
    for (auto it = mSequence.begin(); it < mSequence.end(); ++it)
    {
        if (*it == original)
        {
            it = mSequence.erase(it);
            mSequence.insert(it, replacements.begin(), replacements.end());
            return true;
        }
    }
    return false;
}

bool TIntermAggregate::insertChildNodes(TIntermSequence::size_type position, TIntermSequence insertions)
{
    if (position > mSequence.size())
    {
        return false;
    }
    auto it = mSequence.begin() + position;
    mSequence.insert(it, insertions.begin(), insertions.end());
    return true;
}

bool TIntermAggregate::areChildrenConstQualified()
{
    for (TIntermNode *&child : mSequence)
    {
        TIntermTyped *typed = child->getAsTyped();
        if (typed && typed->getQualifier() != EvqConst)
        {
            return false;
        }
    }
    return true;
}

void TIntermAggregate::setPrecisionFromChildren()
{
    mGotPrecisionFromChildren = true;
    if (getBasicType() == EbtBool)
    {
        mType.setPrecision(EbpUndefined);
        return;
    }

    TPrecision precision = EbpUndefined;
    TIntermSequence::iterator childIter = mSequence.begin();
    while (childIter != mSequence.end())
    {
        TIntermTyped *typed = (*childIter)->getAsTyped();
        if (typed)
            precision = GetHigherPrecision(typed->getPrecision(), precision);
        ++childIter;
    }
    mType.setPrecision(precision);
}

void TIntermAggregate::setBuiltInFunctionPrecision()
{
    // All built-ins returning bool should be handled as ops, not functions.
    ASSERT(getBasicType() != EbtBool);

    TPrecision precision = EbpUndefined;
    TIntermSequence::iterator childIter = mSequence.begin();
    while (childIter != mSequence.end())
    {
        TIntermTyped *typed = (*childIter)->getAsTyped();
        // ESSL spec section 8: texture functions get their precision from the sampler.
        if (typed && IsSampler(typed->getBasicType()))
        {
            precision = typed->getPrecision();
            break;
        }
        ++childIter;
    }
    // ESSL 3.0 spec section 8: textureSize always gets highp precision.
    // All other functions that take a sampler are assumed to be texture functions.
    if (mName.getString().find("textureSize") == 0)
        mType.setPrecision(EbpHigh);
    else
        mType.setPrecision(precision);
}

bool TIntermSelection::replaceChildNode(
    TIntermNode *original, TIntermNode *replacement)
{
    REPLACE_IF_IS(mCondition, TIntermTyped, original, replacement);
    REPLACE_IF_IS(mTrueBlock, TIntermNode, original, replacement);
    REPLACE_IF_IS(mFalseBlock, TIntermNode, original, replacement);
    return false;
}

bool TIntermSwitch::replaceChildNode(
    TIntermNode *original, TIntermNode *replacement)
{
    REPLACE_IF_IS(mInit, TIntermTyped, original, replacement);
    REPLACE_IF_IS(mStatementList, TIntermAggregate, original, replacement);
    return false;
}

bool TIntermCase::replaceChildNode(
    TIntermNode *original, TIntermNode *replacement)
{
    REPLACE_IF_IS(mCondition, TIntermTyped, original, replacement);
    return false;
}

TIntermTyped::TIntermTyped(const TIntermTyped &node) : TIntermNode(), mType(node.mType)
{
    // Copy constructor is disallowed for TIntermNode in order to disallow it for subclasses that
    // don't explicitly allow it, so normal TIntermNode constructor is used to construct the copy.
    // We need to manually copy any fields of TIntermNode besides handling fields in TIntermTyped.
    mLine = node.mLine;
}

bool TIntermTyped::isConstructorWithOnlyConstantUnionParameters()
{
    TIntermAggregate *constructor = getAsAggregate();
    if (!constructor || !constructor->isConstructor())
    {
        return false;
    }
    for (TIntermNode *&node : *constructor->getSequence())
    {
        if (!node->getAsConstantUnion())
            return false;
    }
    return true;
}

// static
TIntermTyped *TIntermTyped::CreateIndexNode(int index)
{
    TConstantUnion *u = new TConstantUnion[1];
    u[0].setIConst(index);

    TType type(EbtInt, EbpUndefined, EvqConst, 1);
    TIntermConstantUnion *node = new TIntermConstantUnion(u, type);
    return node;
}

// static
TIntermTyped *TIntermTyped::CreateZero(const TType &type)
{
    TType constType(type);
    constType.setQualifier(EvqConst);

    if (!type.isArray() && type.getBasicType() != EbtStruct)
    {
        ASSERT(type.isScalar() || type.isVector() || type.isMatrix());

        size_t size       = constType.getObjectSize();
        TConstantUnion *u = new TConstantUnion[size];
        for (size_t i = 0; i < size; ++i)
        {
            switch (type.getBasicType())
            {
                case EbtFloat:
                    u[i].setFConst(0.0f);
                    break;
                case EbtInt:
                    u[i].setIConst(0);
                    break;
                case EbtUInt:
                    u[i].setUConst(0u);
                    break;
                case EbtBool:
                    u[i].setBConst(false);
                    break;
                default:
                    UNREACHABLE();
                    return nullptr;
            }
        }

        TIntermConstantUnion *node = new TIntermConstantUnion(u, constType);
        return node;
    }

    TIntermAggregate *constructor = new TIntermAggregate(sh::TypeToConstructorOperator(type));
    constructor->setType(constType);

    if (type.isArray())
    {
        TType elementType(type);
        elementType.clearArrayness();

        size_t arraySize = type.getArraySize();
        for (size_t i = 0; i < arraySize; ++i)
        {
            constructor->getSequence()->push_back(CreateZero(elementType));
        }
    }
    else
    {
        ASSERT(type.getBasicType() == EbtStruct);

        TStructure *structure = type.getStruct();
        for (const auto &field : structure->fields())
        {
            constructor->getSequence()->push_back(CreateZero(*field->type()));
        }
    }

    return constructor;
}

TIntermConstantUnion::TIntermConstantUnion(const TIntermConstantUnion &node) : TIntermTyped(node)
{
    mUnionArrayPointer = node.mUnionArrayPointer;
}

TIntermAggregate::TIntermAggregate(const TIntermAggregate &node)
    : TIntermOperator(node),
      mName(node.mName),
      mUserDefined(node.mUserDefined),
      mFunctionId(node.mFunctionId),
      mUseEmulatedFunction(node.mUseEmulatedFunction),
      mGotPrecisionFromChildren(node.mGotPrecisionFromChildren)
{
    for (TIntermNode *child : node.mSequence)
    {
        TIntermTyped *typedChild = child->getAsTyped();
        ASSERT(typedChild != nullptr);
        TIntermTyped *childCopy = typedChild->deepCopy();
        mSequence.push_back(childCopy);
    }
}

TIntermBinary::TIntermBinary(const TIntermBinary &node)
    : TIntermOperator(node), mAddIndexClamp(node.mAddIndexClamp)
{
    TIntermTyped *leftCopy  = node.mLeft->deepCopy();
    TIntermTyped *rightCopy = node.mRight->deepCopy();
    ASSERT(leftCopy != nullptr && rightCopy != nullptr);
    mLeft  = leftCopy;
    mRight = rightCopy;
}

TIntermUnary::TIntermUnary(const TIntermUnary &node)
    : TIntermOperator(node), mUseEmulatedFunction(node.mUseEmulatedFunction)
{
    TIntermTyped *operandCopy = node.mOperand->deepCopy();
    ASSERT(operandCopy != nullptr);
    mOperand = operandCopy;
}

TIntermSelection::TIntermSelection(const TIntermSelection &node) : TIntermTyped(node)
{
    // Only supported for ternary nodes, not if statements.
    TIntermTyped *trueTyped  = node.mTrueBlock->getAsTyped();
    TIntermTyped *falseTyped = node.mFalseBlock->getAsTyped();
    ASSERT(trueTyped != nullptr);
    ASSERT(falseTyped != nullptr);
    TIntermTyped *conditionCopy = node.mCondition->deepCopy();
    TIntermTyped *trueCopy      = trueTyped->deepCopy();
    TIntermTyped *falseCopy = falseTyped->deepCopy();
    ASSERT(conditionCopy != nullptr && trueCopy != nullptr && falseCopy != nullptr);
    mCondition  = conditionCopy;
    mTrueBlock  = trueCopy;
    mFalseBlock = falseCopy;
}

bool TIntermOperator::isAssignment() const
{
    return IsAssignment(mOp);
}

bool TIntermOperator::isMultiplication() const
{
    switch (mOp)
    {
      case EOpMul:
      case EOpMatrixTimesMatrix:
      case EOpMatrixTimesVector:
      case EOpMatrixTimesScalar:
      case EOpVectorTimesMatrix:
      case EOpVectorTimesScalar:
        return true;
      default:
        return false;
    }
}

//
// returns true if the operator is for one of the constructors
//
bool TIntermOperator::isConstructor() const
{
    switch (mOp)
    {
      case EOpConstructVec2:
      case EOpConstructVec3:
      case EOpConstructVec4:
      case EOpConstructMat2:
      case EOpConstructMat2x3:
      case EOpConstructMat2x4:
      case EOpConstructMat3x2:
      case EOpConstructMat3:
      case EOpConstructMat3x4:
      case EOpConstructMat4x2:
      case EOpConstructMat4x3:
      case EOpConstructMat4:
      case EOpConstructFloat:
      case EOpConstructIVec2:
      case EOpConstructIVec3:
      case EOpConstructIVec4:
      case EOpConstructInt:
      case EOpConstructUVec2:
      case EOpConstructUVec3:
      case EOpConstructUVec4:
      case EOpConstructUInt:
      case EOpConstructBVec2:
      case EOpConstructBVec3:
      case EOpConstructBVec4:
      case EOpConstructBool:
      case EOpConstructStruct:
        return true;
      default:
        return false;
    }
}

TOperator TIntermBinary::GetMulOpBasedOnOperands(const TType &left, const TType &right)
{
    if (left.isMatrix())
    {
        if (right.isMatrix())
        {
            return EOpMatrixTimesMatrix;
        }
        else
        {
            if (right.isVector())
            {
                return EOpMatrixTimesVector;
            }
            else
            {
                return EOpMatrixTimesScalar;
            }
        }
    }
    else
    {
        if (right.isMatrix())
        {
            if (left.isVector())
            {
                return EOpVectorTimesMatrix;
            }
            else
            {
                return EOpMatrixTimesScalar;
            }
        }
        else
        {
            // Neither operand is a matrix.
            if (left.isVector() == right.isVector())
            {
                // Leave as component product.
                return EOpMul;
            }
            else
            {
                return EOpVectorTimesScalar;
            }
        }
    }
}

TOperator TIntermBinary::GetMulAssignOpBasedOnOperands(const TType &left, const TType &right)
{
    if (left.isMatrix())
    {
        if (right.isMatrix())
        {
            return EOpMatrixTimesMatrixAssign;
        }
        else
        {
            // right should be scalar, but this may not be validated yet.
            return EOpMatrixTimesScalarAssign;
        }
    }
    else
    {
        if (right.isMatrix())
        {
            // Left should be a vector, but this may not be validated yet.
            return EOpVectorTimesMatrixAssign;
        }
        else
        {
            // Neither operand is a matrix.
            if (left.isVector() == right.isVector())
            {
                // Leave as component product.
                return EOpMulAssign;
            }
            else
            {
                // left should be vector and right should be scalar, but this may not be validated
                // yet.
                return EOpVectorTimesScalarAssign;
            }
        }
    }
}

//
// Make sure the type of a unary operator is appropriate for its
// combination of operation and operand type.
//
void TIntermUnary::promote(const TType *funcReturnType)
{
    switch (mOp)
    {
      case EOpFloatBitsToInt:
      case EOpFloatBitsToUint:
      case EOpIntBitsToFloat:
      case EOpUintBitsToFloat:
      case EOpPackSnorm2x16:
      case EOpPackUnorm2x16:
      case EOpPackHalf2x16:
      case EOpUnpackSnorm2x16:
      case EOpUnpackUnorm2x16:
        mType.setPrecision(EbpHigh);
        break;
      case EOpUnpackHalf2x16:
        mType.setPrecision(EbpMedium);
        break;
      default:
        setType(mOperand->getType());
    }

    if (funcReturnType != nullptr)
    {
        if (funcReturnType->getBasicType() == EbtBool)
        {
            // Bool types should not have precision.
            setType(*funcReturnType);
        }
        else
        {
            // Precision of the node has been set based on the operand.
            setTypePreservePrecision(*funcReturnType);
        }
    }

    if (mOperand->getQualifier() == EvqConst)
        mType.setQualifier(EvqConst);
    else
        mType.setQualifier(EvqTemporary);
}

TIntermBinary::TIntermBinary(TOperator op, TIntermTyped *left, TIntermTyped *right)
    : TIntermOperator(op), mLeft(left), mRight(right), mAddIndexClamp(false)
{
    promote();
}

//
// Establishes the type of the resultant operation, as well as
// makes the operator the correct one for the operands.
//
// For lots of operations it should already be established that the operand
// combination is valid, but returns false if operator can't work on operands.
//
void TIntermBinary::promote()
{
    ASSERT(mLeft->isArray() == mRight->isArray());

    ASSERT(!isMultiplication() ||
           mOp == GetMulOpBasedOnOperands(mLeft->getType(), mRight->getType()));

    // Base assumption:  just make the type the same as the left
    // operand.  Then only deviations from this need be coded.
    setType(mLeft->getType());

    // The result gets promoted to the highest precision.
    TPrecision higherPrecision = GetHigherPrecision(
        mLeft->getPrecision(), mRight->getPrecision());
    getTypePointer()->setPrecision(higherPrecision);

    TQualifier resultQualifier = EvqConst;
    // Binary operations results in temporary variables unless both
    // operands are const.
    if (mLeft->getQualifier() != EvqConst || mRight->getQualifier() != EvqConst)
    {
        resultQualifier = EvqTemporary;
        getTypePointer()->setQualifier(EvqTemporary);
    }

    const int nominalSize =
        std::max(mLeft->getNominalSize(), mRight->getNominalSize());

    //
    // All scalars or structs. Code after this test assumes this case is removed!
    //
    if (nominalSize == 1)
    {
        switch (mOp)
        {
          //
          // Promote to conditional
          //
          case EOpEqual:
          case EOpNotEqual:
          case EOpLessThan:
          case EOpGreaterThan:
          case EOpLessThanEqual:
          case EOpGreaterThanEqual:
            setType(TType(EbtBool, EbpUndefined, resultQualifier));
            break;

          //
          // And and Or operate on conditionals
          //
          case EOpLogicalAnd:
          case EOpLogicalXor:
          case EOpLogicalOr:
            ASSERT(mLeft->getBasicType() == EbtBool && mRight->getBasicType() == EbtBool);
            setType(TType(EbtBool, EbpUndefined, resultQualifier));
            break;

          default:
            break;
        }
        return;
    }

    // If we reach here, at least one of the operands is vector or matrix.
    // The other operand could be a scalar, vector, or matrix.
    TBasicType basicType = mLeft->getBasicType();

    switch (mOp)
    {
        case EOpMul:
            break;
        case EOpMatrixTimesScalar:
            if (mRight->isMatrix())
            {
                setType(TType(basicType, higherPrecision, resultQualifier,
                              static_cast<unsigned char>(mRight->getCols()),
                              static_cast<unsigned char>(mRight->getRows())));
            }
            break;
        case EOpMatrixTimesVector:
            setType(TType(basicType, higherPrecision, resultQualifier,
                          static_cast<unsigned char>(mLeft->getRows()), 1));
            break;
        case EOpMatrixTimesMatrix:
            setType(TType(basicType, higherPrecision, resultQualifier,
                          static_cast<unsigned char>(mRight->getCols()),
                          static_cast<unsigned char>(mLeft->getRows())));
            break;
        case EOpVectorTimesScalar:
            setType(TType(basicType, higherPrecision, resultQualifier,
                          static_cast<unsigned char>(nominalSize), 1));
            break;
        case EOpVectorTimesMatrix:
            setType(TType(basicType, higherPrecision, resultQualifier,
                          static_cast<unsigned char>(mRight->getCols()), 1));
            break;
        case EOpMulAssign:
        case EOpVectorTimesScalarAssign:
        case EOpVectorTimesMatrixAssign:
        case EOpMatrixTimesScalarAssign:
        case EOpMatrixTimesMatrixAssign:
            ASSERT(mOp == GetMulAssignOpBasedOnOperands(mLeft->getType(), mRight->getType()));
            break;
        case EOpAssign:
        case EOpInitialize:
            ASSERT((mLeft->getNominalSize() == mRight->getNominalSize()) &&
                   (mLeft->getSecondarySize() == mRight->getSecondarySize()));
            break;
        case EOpAdd:
        case EOpSub:
        case EOpDiv:
        case EOpIMod:
        case EOpBitShiftLeft:
        case EOpBitShiftRight:
        case EOpBitwiseAnd:
        case EOpBitwiseXor:
        case EOpBitwiseOr:
        case EOpAddAssign:
        case EOpSubAssign:
        case EOpDivAssign:
        case EOpIModAssign:
        case EOpBitShiftLeftAssign:
        case EOpBitShiftRightAssign:
        case EOpBitwiseAndAssign:
        case EOpBitwiseXorAssign:
        case EOpBitwiseOrAssign:
        {
            const int secondarySize =
                std::max(mLeft->getSecondarySize(), mRight->getSecondarySize());
            setType(TType(basicType, higherPrecision, resultQualifier,
                          static_cast<unsigned char>(nominalSize),
                          static_cast<unsigned char>(secondarySize)));
            ASSERT(!mLeft->isArray() && !mRight->isArray());
            break;
        }
        case EOpEqual:
        case EOpNotEqual:
        case EOpLessThan:
        case EOpGreaterThan:
        case EOpLessThanEqual:
        case EOpGreaterThanEqual:
            ASSERT((mLeft->getNominalSize() == mRight->getNominalSize()) &&
                   (mLeft->getSecondarySize() == mRight->getSecondarySize()));
            setType(TType(EbtBool, EbpUndefined, resultQualifier));
            break;

        case EOpIndexDirect:
        case EOpIndexIndirect:
        case EOpIndexDirectInterfaceBlock:
        case EOpIndexDirectStruct:
            // TODO (oetuaho): These ops could be handled here as well (should be done closer to the
            // top of the function).
            UNREACHABLE();
            break;
        default:
            UNREACHABLE();
            break;
    }
}

TIntermTyped *TIntermBinary::fold(TDiagnostics *diagnostics)
{
    TIntermConstantUnion *leftConstant = mLeft->getAsConstantUnion();
    TIntermConstantUnion *rightConstant = mRight->getAsConstantUnion();
    if (leftConstant == nullptr || rightConstant == nullptr)
    {
        return nullptr;
    }
    TConstantUnion *constArray = leftConstant->foldBinary(mOp, rightConstant, diagnostics);

    // Nodes may be constant folded without being qualified as constant.
    return CreateFoldedNode(constArray, this, mType.getQualifier());
}

TIntermTyped *TIntermUnary::fold(TDiagnostics *diagnostics)
{
    TIntermConstantUnion *operandConstant = mOperand->getAsConstantUnion();
    if (operandConstant == nullptr)
    {
        return nullptr;
    }

    TConstantUnion *constArray = nullptr;
    switch (mOp)
    {
      case EOpAny:
      case EOpAll:
      case EOpLength:
      case EOpTranspose:
      case EOpDeterminant:
      case EOpInverse:
      case EOpPackSnorm2x16:
      case EOpUnpackSnorm2x16:
      case EOpPackUnorm2x16:
      case EOpUnpackUnorm2x16:
      case EOpPackHalf2x16:
      case EOpUnpackHalf2x16:
          constArray = operandConstant->foldUnaryNonComponentWise(mOp);
          break;
      default:
          constArray = operandConstant->foldUnaryComponentWise(mOp, diagnostics);
          break;
    }

    // Nodes may be constant folded without being qualified as constant.
    return CreateFoldedNode(constArray, this, mType.getQualifier());
}

TIntermTyped *TIntermAggregate::fold(TDiagnostics *diagnostics)
{
    // Make sure that all params are constant before actual constant folding.
    for (auto *param : *getSequence())
    {
        if (param->getAsConstantUnion() == nullptr)
        {
            return nullptr;
        }
    }
    TConstantUnion *constArray = nullptr;
    if (isConstructor())
        constArray = TIntermConstantUnion::FoldAggregateConstructor(this);
    else
        constArray = TIntermConstantUnion::FoldAggregateBuiltIn(this, diagnostics);

    // Nodes may be constant folded without being qualified as constant.
    TQualifier resultQualifier = areChildrenConstQualified() ? EvqConst : EvqTemporary;
    return CreateFoldedNode(constArray, this, resultQualifier);
}

//
// The fold functions see if an operation on a constant can be done in place,
// without generating run-time code.
//
// Returns the constant value to keep using or nullptr.
//
TConstantUnion *TIntermConstantUnion::foldBinary(TOperator op,
                                                 TIntermConstantUnion *rightNode,
                                                 TDiagnostics *diagnostics)
{
    const TConstantUnion *leftArray  = getUnionArrayPointer();
    const TConstantUnion *rightArray = rightNode->getUnionArrayPointer();

    ASSERT(leftArray && rightArray);

    size_t objectSize = getType().getObjectSize();

    // for a case like float f = vec4(2, 3, 4, 5) + 1.2;
    if (rightNode->getType().getObjectSize() == 1 && objectSize > 1)
    {
        rightArray = Vectorize(*rightNode->getUnionArrayPointer(), objectSize);
    }
    else if (rightNode->getType().getObjectSize() > 1 && objectSize == 1)
    {
        // for a case like float f = 1.2 + vec4(2, 3, 4, 5);
        leftArray = Vectorize(*getUnionArrayPointer(), rightNode->getType().getObjectSize());
        objectSize = rightNode->getType().getObjectSize();
    }

    TConstantUnion *resultArray = nullptr;

    switch(op)
    {
      case EOpAdd:
        resultArray = new TConstantUnion[objectSize];
        for (size_t i = 0; i < objectSize; i++)
            resultArray[i] = leftArray[i] + rightArray[i];
        break;
      case EOpSub:
        resultArray = new TConstantUnion[objectSize];
        for (size_t i = 0; i < objectSize; i++)
            resultArray[i] = leftArray[i] - rightArray[i];
        break;

      case EOpMul:
      case EOpVectorTimesScalar:
      case EOpMatrixTimesScalar:
        resultArray = new TConstantUnion[objectSize];
        for (size_t i = 0; i < objectSize; i++)
            resultArray[i] = leftArray[i] * rightArray[i];
        break;

      case EOpMatrixTimesMatrix:
        {
            ASSERT(getType().getBasicType() == EbtFloat && rightNode->getBasicType() == EbtFloat);

            const int leftCols = getCols();
            const int leftRows = getRows();
            const int rightCols = rightNode->getType().getCols();
            const int rightRows = rightNode->getType().getRows();
            const int resultCols = rightCols;
            const int resultRows = leftRows;

            resultArray = new TConstantUnion[resultCols * resultRows];
            for (int row = 0; row < resultRows; row++)
            {
                for (int column = 0; column < resultCols; column++)
                {
                    resultArray[resultRows * column + row].setFConst(0.0f);
                    for (int i = 0; i < leftCols; i++)
                    {
                        resultArray[resultRows * column + row].setFConst(
                            resultArray[resultRows * column + row].getFConst() +
                            leftArray[i * leftRows + row].getFConst() *
                            rightArray[column * rightRows + i].getFConst());
                    }
                }
            }
        }
        break;

      case EOpDiv:
      case EOpIMod:
        {
            resultArray = new TConstantUnion[objectSize];
            for (size_t i = 0; i < objectSize; i++)
            {
                switch (getType().getBasicType())
                {
                  case EbtFloat:
                    if (rightArray[i] == 0.0f)
                    {
                        diagnostics->warning(
                            getLine(), "Divide by zero error during constant folding", "/", "");
                        resultArray[i].setFConst(leftArray[i].getFConst() < 0 ? -FLT_MAX : FLT_MAX);
                    }
                    else
                    {
                        ASSERT(op == EOpDiv);
                        resultArray[i].setFConst(leftArray[i].getFConst() / rightArray[i].getFConst());
                    }
                    break;

                  case EbtInt:
                    if (rightArray[i] == 0)
                    {
                        diagnostics->warning(
                            getLine(), "Divide by zero error during constant folding", "/", "");
                        resultArray[i].setIConst(INT_MAX);
                    }
                    else
                    {
                        if (op == EOpDiv)
                        {
                            resultArray[i].setIConst(leftArray[i].getIConst() / rightArray[i].getIConst());
                        }
                        else
                        {
                            ASSERT(op == EOpIMod);
                            resultArray[i].setIConst(leftArray[i].getIConst() % rightArray[i].getIConst());
                        }
                    }
                    break;

                  case EbtUInt:
                    if (rightArray[i] == 0)
                    {
                        diagnostics->warning(
                            getLine(), "Divide by zero error during constant folding", "/", "");
                        resultArray[i].setUConst(UINT_MAX);
                    }
                    else
                    {
                        if (op == EOpDiv)
                        {
                            resultArray[i].setUConst(leftArray[i].getUConst() / rightArray[i].getUConst());
                        }
                        else
                        {
                            ASSERT(op == EOpIMod);
                            resultArray[i].setUConst(leftArray[i].getUConst() % rightArray[i].getUConst());
                        }
                    }
                    break;

                  default:
                      UNREACHABLE();
                      return nullptr;
                }
            }
        }
        break;

      case EOpMatrixTimesVector:
        {
            ASSERT(rightNode->getBasicType() == EbtFloat);

            const int matrixCols = getCols();
            const int matrixRows = getRows();

            resultArray = new TConstantUnion[matrixRows];

            for (int matrixRow = 0; matrixRow < matrixRows; matrixRow++)
            {
                resultArray[matrixRow].setFConst(0.0f);
                for (int col = 0; col < matrixCols; col++)
                {
                    resultArray[matrixRow].setFConst(resultArray[matrixRow].getFConst() +
                                                     leftArray[col * matrixRows + matrixRow].getFConst() *
                                                     rightArray[col].getFConst());
                }
            }
        }
        break;

      case EOpVectorTimesMatrix:
        {
            ASSERT(getType().getBasicType() == EbtFloat);

            const int matrixCols = rightNode->getType().getCols();
            const int matrixRows = rightNode->getType().getRows();

            resultArray = new TConstantUnion[matrixCols];

            for (int matrixCol = 0; matrixCol < matrixCols; matrixCol++)
            {
                resultArray[matrixCol].setFConst(0.0f);
                for (int matrixRow = 0; matrixRow < matrixRows; matrixRow++)
                {
                    resultArray[matrixCol].setFConst(resultArray[matrixCol].getFConst() +
                                                     leftArray[matrixRow].getFConst() *
                                                     rightArray[matrixCol * matrixRows + matrixRow].getFConst());
                }
            }
        }
        break;

      case EOpLogicalAnd:
        {
            resultArray = new TConstantUnion[objectSize];
            for (size_t i = 0; i < objectSize; i++)
            {
                resultArray[i] = leftArray[i] && rightArray[i];
            }
        }
        break;

      case EOpLogicalOr:
        {
            resultArray = new TConstantUnion[objectSize];
            for (size_t i = 0; i < objectSize; i++)
            {
                resultArray[i] = leftArray[i] || rightArray[i];
            }
        }
        break;

      case EOpLogicalXor:
        {
            ASSERT(getType().getBasicType() == EbtBool);
            resultArray = new TConstantUnion[objectSize];
            for (size_t i = 0; i < objectSize; i++)
            {
                resultArray[i].setBConst(leftArray[i] != rightArray[i]);
            }
        }
        break;

      case EOpBitwiseAnd:
        resultArray = new TConstantUnion[objectSize];
        for (size_t i = 0; i < objectSize; i++)
            resultArray[i] = leftArray[i] & rightArray[i];
        break;
      case EOpBitwiseXor:
        resultArray = new TConstantUnion[objectSize];
        for (size_t i = 0; i < objectSize; i++)
            resultArray[i] = leftArray[i] ^ rightArray[i];
        break;
      case EOpBitwiseOr:
        resultArray = new TConstantUnion[objectSize];
        for (size_t i = 0; i < objectSize; i++)
            resultArray[i] = leftArray[i] | rightArray[i];
        break;
      case EOpBitShiftLeft:
        resultArray = new TConstantUnion[objectSize];
        for (size_t i = 0; i < objectSize; i++)
            resultArray[i] = leftArray[i] << rightArray[i];
        break;
      case EOpBitShiftRight:
        resultArray = new TConstantUnion[objectSize];
        for (size_t i = 0; i < objectSize; i++)
            resultArray[i] = leftArray[i] >> rightArray[i];
        break;

      case EOpLessThan:
        ASSERT(objectSize == 1);
        resultArray = new TConstantUnion[1];
        resultArray->setBConst(*leftArray < *rightArray);
        break;

      case EOpGreaterThan:
        ASSERT(objectSize == 1);
        resultArray = new TConstantUnion[1];
        resultArray->setBConst(*leftArray > *rightArray);
        break;

      case EOpLessThanEqual:
        ASSERT(objectSize == 1);
        resultArray = new TConstantUnion[1];
        resultArray->setBConst(!(*leftArray > *rightArray));
        break;

      case EOpGreaterThanEqual:
        ASSERT(objectSize == 1);
        resultArray = new TConstantUnion[1];
        resultArray->setBConst(!(*leftArray < *rightArray));
        break;

      case EOpEqual:
      case EOpNotEqual:
        {
            resultArray = new TConstantUnion[1];
            bool equal = true;
            for (size_t i = 0; i < objectSize; i++)
            {
                if (leftArray[i] != rightArray[i])
                {
                    equal = false;
                    break;  // break out of for loop
                }
            }
            if (op == EOpEqual)
            {
                resultArray->setBConst(equal);
            }
            else
            {
                resultArray->setBConst(!equal);
            }
        }
        break;

      default:
          UNREACHABLE();
          return nullptr;
    }
    return resultArray;
}

// The fold functions do operations on a constant at GLSL compile time, without generating run-time
// code. Returns the constant value to keep using. Nullptr should not be returned.
TConstantUnion *TIntermConstantUnion::foldUnaryNonComponentWise(TOperator op)
{
    // Do operations where the return type may have a different number of components compared to the
    // operand type.

    const TConstantUnion *operandArray = getUnionArrayPointer();
    ASSERT(operandArray);

    size_t objectSize = getType().getObjectSize();
    TConstantUnion *resultArray = nullptr;
    switch (op)
    {
        case EOpAny:
            ASSERT(getType().getBasicType() == EbtBool);
            resultArray = new TConstantUnion();
            resultArray->setBConst(false);
            for (size_t i = 0; i < objectSize; i++)
            {
                if (operandArray[i].getBConst())
                {
                    resultArray->setBConst(true);
                    break;
                }
            }
            break;

        case EOpAll:
            ASSERT(getType().getBasicType() == EbtBool);
            resultArray = new TConstantUnion();
            resultArray->setBConst(true);
            for (size_t i = 0; i < objectSize; i++)
            {
                if (!operandArray[i].getBConst())
                {
                    resultArray->setBConst(false);
                    break;
                }
            }
            break;

        case EOpLength:
            ASSERT(getType().getBasicType() == EbtFloat);
            resultArray = new TConstantUnion();
            resultArray->setFConst(VectorLength(operandArray, objectSize));
            break;

        case EOpTranspose:
        {
            ASSERT(getType().getBasicType() == EbtFloat);
            resultArray = new TConstantUnion[objectSize];
            angle::Matrix<float> result =
                GetMatrix(operandArray, getType().getRows(), getType().getCols()).transpose();
            SetUnionArrayFromMatrix(result, resultArray);
            break;
        }

        case EOpDeterminant:
        {
            ASSERT(getType().getBasicType() == EbtFloat);
            unsigned int size = getType().getNominalSize();
            ASSERT(size >= 2 && size <= 4);
            resultArray = new TConstantUnion();
            resultArray->setFConst(GetMatrix(operandArray, size).determinant());
            break;
        }

        case EOpInverse:
        {
            ASSERT(getType().getBasicType() == EbtFloat);
            unsigned int size = getType().getNominalSize();
            ASSERT(size >= 2 && size <= 4);
            resultArray                 = new TConstantUnion[objectSize];
            angle::Matrix<float> result = GetMatrix(operandArray, size).inverse();
            SetUnionArrayFromMatrix(result, resultArray);
            break;
        }

        case EOpPackSnorm2x16:
            ASSERT(getType().getBasicType() == EbtFloat);
            ASSERT(getType().getNominalSize() == 2);
            resultArray = new TConstantUnion();
            resultArray->setUConst(
                gl::packSnorm2x16(operandArray[0].getFConst(), operandArray[1].getFConst()));
            break;

        case EOpUnpackSnorm2x16:
        {
            ASSERT(getType().getBasicType() == EbtUInt);
            resultArray = new TConstantUnion[2];
            float f1, f2;
            gl::unpackSnorm2x16(operandArray[0].getUConst(), &f1, &f2);
            resultArray[0].setFConst(f1);
            resultArray[1].setFConst(f2);
            break;
        }

        case EOpPackUnorm2x16:
            ASSERT(getType().getBasicType() == EbtFloat);
            ASSERT(getType().getNominalSize() == 2);
            resultArray = new TConstantUnion();
            resultArray->setUConst(
                gl::packUnorm2x16(operandArray[0].getFConst(), operandArray[1].getFConst()));
            break;

        case EOpUnpackUnorm2x16:
        {
            ASSERT(getType().getBasicType() == EbtUInt);
            resultArray = new TConstantUnion[2];
            float f1, f2;
            gl::unpackUnorm2x16(operandArray[0].getUConst(), &f1, &f2);
            resultArray[0].setFConst(f1);
            resultArray[1].setFConst(f2);
            break;
        }

        case EOpPackHalf2x16:
            ASSERT(getType().getBasicType() == EbtFloat);
            ASSERT(getType().getNominalSize() == 2);
            resultArray = new TConstantUnion();
            resultArray->setUConst(
                gl::packHalf2x16(operandArray[0].getFConst(), operandArray[1].getFConst()));
            break;

        case EOpUnpackHalf2x16:
        {
            ASSERT(getType().getBasicType() == EbtUInt);
            resultArray = new TConstantUnion[2];
            float f1, f2;
            gl::unpackHalf2x16(operandArray[0].getUConst(), &f1, &f2);
            resultArray[0].setFConst(f1);
            resultArray[1].setFConst(f2);
            break;
        }

        default:
            UNREACHABLE();
            break;
    }

    return resultArray;
}

TConstantUnion *TIntermConstantUnion::foldUnaryComponentWise(TOperator op,
                                                             TDiagnostics *diagnostics)
{
    // Do unary operations where each component of the result is computed based on the corresponding
    // component of the operand. Also folds normalize, though the divisor in that case takes all
    // components into account.

    const TConstantUnion *operandArray = getUnionArrayPointer();
    ASSERT(operandArray);

    size_t objectSize = getType().getObjectSize();

    TConstantUnion *resultArray = new TConstantUnion[objectSize];
    for (size_t i = 0; i < objectSize; i++)
    {
        switch(op)
        {
            case EOpNegative:
                switch (getType().getBasicType())
                {
                    case EbtFloat:
                        resultArray[i].setFConst(-operandArray[i].getFConst());
                        break;
                    case EbtInt:
                        resultArray[i].setIConst(-operandArray[i].getIConst());
                        break;
                    case EbtUInt:
                        resultArray[i].setUConst(static_cast<unsigned int>(
                            -static_cast<int>(operandArray[i].getUConst())));
                        break;
                    default:
                        UNREACHABLE();
                        return nullptr;
                }
                break;

            case EOpPositive:
                switch (getType().getBasicType())
                {
                    case EbtFloat:
                        resultArray[i].setFConst(operandArray[i].getFConst());
                        break;
                    case EbtInt:
                        resultArray[i].setIConst(operandArray[i].getIConst());
                        break;
                    case EbtUInt:
                        resultArray[i].setUConst(static_cast<unsigned int>(
                            static_cast<int>(operandArray[i].getUConst())));
                        break;
                    default:
                        UNREACHABLE();
                        return nullptr;
                }
                break;

            case EOpLogicalNot:
                switch (getType().getBasicType())
                {
                    case EbtBool:
                        resultArray[i].setBConst(!operandArray[i].getBConst());
                        break;
                    default:
                        UNREACHABLE();
                        return nullptr;
                }
                break;

            case EOpBitwiseNot:
                switch (getType().getBasicType())
                {
                    case EbtInt:
                        resultArray[i].setIConst(~operandArray[i].getIConst());
                        break;
                    case EbtUInt:
                        resultArray[i].setUConst(~operandArray[i].getUConst());
                        break;
                    default:
                        UNREACHABLE();
                        return nullptr;
                }
                break;

            case EOpRadians:
                ASSERT(getType().getBasicType() == EbtFloat);
                resultArray[i].setFConst(kDegreesToRadiansMultiplier * operandArray[i].getFConst());
                break;

            case EOpDegrees:
                ASSERT(getType().getBasicType() == EbtFloat);
                resultArray[i].setFConst(kRadiansToDegreesMultiplier * operandArray[i].getFConst());
                break;

            case EOpSin:
                foldFloatTypeUnary(operandArray[i], &sinf, &resultArray[i]);
                break;

            case EOpCos:
                foldFloatTypeUnary(operandArray[i], &cosf, &resultArray[i]);
                break;

            case EOpTan:
                foldFloatTypeUnary(operandArray[i], &tanf, &resultArray[i]);
                break;

            case EOpAsin:
                // For asin(x), results are undefined if |x| > 1, we are choosing to set result to
                // 0.
                if (fabsf(operandArray[i].getFConst()) > 1.0f)
                    UndefinedConstantFoldingError(getLine(), op, getType().getBasicType(),
                                                  diagnostics, &resultArray[i]);
                else
                    foldFloatTypeUnary(operandArray[i], &asinf, &resultArray[i]);
                break;

            case EOpAcos:
                // For acos(x), results are undefined if |x| > 1, we are choosing to set result to
                // 0.
                if (fabsf(operandArray[i].getFConst()) > 1.0f)
                    UndefinedConstantFoldingError(getLine(), op, getType().getBasicType(),
                                                  diagnostics, &resultArray[i]);
                else
                    foldFloatTypeUnary(operandArray[i], &acosf, &resultArray[i]);
                break;

            case EOpAtan:
                foldFloatTypeUnary(operandArray[i], &atanf, &resultArray[i]);
                break;

            case EOpSinh:
                foldFloatTypeUnary(operandArray[i], &sinhf, &resultArray[i]);
                break;

            case EOpCosh:
                foldFloatTypeUnary(operandArray[i], &coshf, &resultArray[i]);
                break;

            case EOpTanh:
                foldFloatTypeUnary(operandArray[i], &tanhf, &resultArray[i]);
                break;

            case EOpAsinh:
                foldFloatTypeUnary(operandArray[i], &asinhf, &resultArray[i]);
                break;

            case EOpAcosh:
                // For acosh(x), results are undefined if x < 1, we are choosing to set result to 0.
                if (operandArray[i].getFConst() < 1.0f)
                    UndefinedConstantFoldingError(getLine(), op, getType().getBasicType(),
                                                  diagnostics, &resultArray[i]);
                else
                    foldFloatTypeUnary(operandArray[i], &acoshf, &resultArray[i]);
                break;

            case EOpAtanh:
                // For atanh(x), results are undefined if |x| >= 1, we are choosing to set result to
                // 0.
                if (fabsf(operandArray[i].getFConst()) >= 1.0f)
                    UndefinedConstantFoldingError(getLine(), op, getType().getBasicType(),
                                                  diagnostics, &resultArray[i]);
                else
                    foldFloatTypeUnary(operandArray[i], &atanhf, &resultArray[i]);
                break;

            case EOpAbs:
                switch (getType().getBasicType())
                {
                    case EbtFloat:
                        resultArray[i].setFConst(fabsf(operandArray[i].getFConst()));
                        break;
                    case EbtInt:
                        resultArray[i].setIConst(abs(operandArray[i].getIConst()));
                        break;
                    default:
                        UNREACHABLE();
                        return nullptr;
                }
                break;

            case EOpSign:
                switch (getType().getBasicType())
                {
                    case EbtFloat:
                    {
                        float fConst  = operandArray[i].getFConst();
                        float fResult = 0.0f;
                        if (fConst > 0.0f)
                            fResult = 1.0f;
                        else if (fConst < 0.0f)
                            fResult = -1.0f;
                        resultArray[i].setFConst(fResult);
                        break;
                    }
                    case EbtInt:
                    {
                        int iConst  = operandArray[i].getIConst();
                        int iResult = 0;
                        if (iConst > 0)
                            iResult = 1;
                        else if (iConst < 0)
                            iResult = -1;
                        resultArray[i].setIConst(iResult);
                        break;
                    }
                    default:
                        UNREACHABLE();
                        return nullptr;
                }
                break;

            case EOpFloor:
                foldFloatTypeUnary(operandArray[i], &floorf, &resultArray[i]);
                break;

            case EOpTrunc:
                foldFloatTypeUnary(operandArray[i], &truncf, &resultArray[i]);
                break;

            case EOpRound:
                foldFloatTypeUnary(operandArray[i], &roundf, &resultArray[i]);
                break;

            case EOpRoundEven:
            {
                ASSERT(getType().getBasicType() == EbtFloat);
                float x = operandArray[i].getFConst();
                float result;
                float fractPart = modff(x, &result);
                if (fabsf(fractPart) == 0.5f)
                    result = 2.0f * roundf(x / 2.0f);
                else
                    result = roundf(x);
                resultArray[i].setFConst(result);
                break;
            }

            case EOpCeil:
                foldFloatTypeUnary(operandArray[i], &ceilf, &resultArray[i]);
                break;

            case EOpFract:
            {
                ASSERT(getType().getBasicType() == EbtFloat);
                float x = operandArray[i].getFConst();
                resultArray[i].setFConst(x - floorf(x));
                break;
            }

            case EOpIsNan:
                ASSERT(getType().getBasicType() == EbtFloat);
                resultArray[i].setBConst(gl::isNaN(operandArray[0].getFConst()));
                break;

            case EOpIsInf:
                ASSERT(getType().getBasicType() == EbtFloat);
                resultArray[i].setBConst(gl::isInf(operandArray[0].getFConst()));
                break;

            case EOpFloatBitsToInt:
                ASSERT(getType().getBasicType() == EbtFloat);
                resultArray[i].setIConst(gl::bitCast<int32_t>(operandArray[0].getFConst()));
                break;

            case EOpFloatBitsToUint:
                ASSERT(getType().getBasicType() == EbtFloat);
                resultArray[i].setUConst(gl::bitCast<uint32_t>(operandArray[0].getFConst()));
                break;

            case EOpIntBitsToFloat:
                ASSERT(getType().getBasicType() == EbtInt);
                resultArray[i].setFConst(gl::bitCast<float>(operandArray[0].getIConst()));
                break;

            case EOpUintBitsToFloat:
                ASSERT(getType().getBasicType() == EbtUInt);
                resultArray[i].setFConst(gl::bitCast<float>(operandArray[0].getUConst()));
                break;

            case EOpExp:
                foldFloatTypeUnary(operandArray[i], &expf, &resultArray[i]);
                break;

            case EOpLog:
                // For log(x), results are undefined if x <= 0, we are choosing to set result to 0.
                if (operandArray[i].getFConst() <= 0.0f)
                    UndefinedConstantFoldingError(getLine(), op, getType().getBasicType(),
                                                  diagnostics, &resultArray[i]);
                else
                    foldFloatTypeUnary(operandArray[i], &logf, &resultArray[i]);
                break;

            case EOpExp2:
                foldFloatTypeUnary(operandArray[i], &exp2f, &resultArray[i]);
                break;

            case EOpLog2:
                // For log2(x), results are undefined if x <= 0, we are choosing to set result to 0.
                // And log2f is not available on some plarforms like old android, so just using
                // log(x)/log(2) here.
                if (operandArray[i].getFConst() <= 0.0f)
                    UndefinedConstantFoldingError(getLine(), op, getType().getBasicType(),
                                                  diagnostics, &resultArray[i]);
                else
                {
                    foldFloatTypeUnary(operandArray[i], &logf, &resultArray[i]);
                    resultArray[i].setFConst(resultArray[i].getFConst() / logf(2.0f));
                }
                break;

            case EOpSqrt:
                // For sqrt(x), results are undefined if x < 0, we are choosing to set result to 0.
                if (operandArray[i].getFConst() < 0.0f)
                    UndefinedConstantFoldingError(getLine(), op, getType().getBasicType(),
                                                  diagnostics, &resultArray[i]);
                else
                    foldFloatTypeUnary(operandArray[i], &sqrtf, &resultArray[i]);
                break;

            case EOpInverseSqrt:
                // There is no stdlib built-in function equavalent for GLES built-in inversesqrt(),
                // so getting the square root first using builtin function sqrt() and then taking
                // its inverse.
                // Also, for inversesqrt(x), results are undefined if x <= 0, we are choosing to set
                // result to 0.
                if (operandArray[i].getFConst() <= 0.0f)
                    UndefinedConstantFoldingError(getLine(), op, getType().getBasicType(),
                                                  diagnostics, &resultArray[i]);
                else
                {
                    foldFloatTypeUnary(operandArray[i], &sqrtf, &resultArray[i]);
                    resultArray[i].setFConst(1.0f / resultArray[i].getFConst());
                }
                break;

            case EOpVectorLogicalNot:
                ASSERT(getType().getBasicType() == EbtBool);
                resultArray[i].setBConst(!operandArray[i].getBConst());
                break;

            case EOpNormalize:
            {
                ASSERT(getType().getBasicType() == EbtFloat);
                float x      = operandArray[i].getFConst();
                float length = VectorLength(operandArray, objectSize);
                if (length)
                    resultArray[i].setFConst(x / length);
                else
                    UndefinedConstantFoldingError(getLine(), op, getType().getBasicType(),
                                                  diagnostics, &resultArray[i]);
                break;
            }

            case EOpDFdx:
            case EOpDFdy:
            case EOpFwidth:
                ASSERT(getType().getBasicType() == EbtFloat);
                // Derivatives of constant arguments should be 0.
                resultArray[i].setFConst(0.0f);
                break;

            default:
                return nullptr;
        }
    }

    return resultArray;
}

void TIntermConstantUnion::foldFloatTypeUnary(const TConstantUnion &parameter,
                                              FloatTypeUnaryFunc builtinFunc,
                                              TConstantUnion *result) const
{
    ASSERT(builtinFunc);

    ASSERT(getType().getBasicType() == EbtFloat);
    result->setFConst(builtinFunc(parameter.getFConst()));
}

// static
TConstantUnion *TIntermConstantUnion::FoldAggregateConstructor(TIntermAggregate *aggregate)
{
    ASSERT(aggregate->getSequence()->size() > 0u);
    size_t resultSize           = aggregate->getType().getObjectSize();
    TConstantUnion *resultArray = new TConstantUnion[resultSize];
    TBasicType basicType        = aggregate->getBasicType();

    size_t resultIndex = 0u;

    if (aggregate->getSequence()->size() == 1u)
    {
        TIntermNode *argument                    = aggregate->getSequence()->front();
        TIntermConstantUnion *argumentConstant   = argument->getAsConstantUnion();
        const TConstantUnion *argumentUnionArray = argumentConstant->getUnionArrayPointer();
        // Check the special case of constructing a matrix diagonal from a single scalar,
        // or a vector from a single scalar.
        if (argumentConstant->getType().getObjectSize() == 1u)
        {
            if (aggregate->isMatrix())
            {
                int resultCols = aggregate->getType().getCols();
                int resultRows = aggregate->getType().getRows();
                for (int col = 0; col < resultCols; ++col)
                {
                    for (int row = 0; row < resultRows; ++row)
                    {
                        if (col == row)
                        {
                            resultArray[resultIndex].cast(basicType, argumentUnionArray[0]);
                        }
                        else
                        {
                            resultArray[resultIndex].setFConst(0.0f);
                        }
                        ++resultIndex;
                    }
                }
            }
            else
            {
                while (resultIndex < resultSize)
                {
                    resultArray[resultIndex].cast(basicType, argumentUnionArray[0]);
                    ++resultIndex;
                }
            }
            ASSERT(resultIndex == resultSize);
            return resultArray;
        }
        else if (aggregate->isMatrix() && argumentConstant->isMatrix())
        {
            // The special case of constructing a matrix from a matrix.
            int argumentCols = argumentConstant->getType().getCols();
            int argumentRows = argumentConstant->getType().getRows();
            int resultCols   = aggregate->getType().getCols();
            int resultRows = aggregate->getType().getRows();
            for (int col = 0; col < resultCols; ++col)
            {
                for (int row = 0; row < resultRows; ++row)
                {
                    if (col < argumentCols && row < argumentRows)
                    {
                        resultArray[resultIndex].cast(basicType,
                                                      argumentUnionArray[col * argumentRows + row]);
                    }
                    else if (col == row)
                    {
                        resultArray[resultIndex].setFConst(1.0f);
                    }
                    else
                    {
                        resultArray[resultIndex].setFConst(0.0f);
                    }
                    ++resultIndex;
                }
            }
            ASSERT(resultIndex == resultSize);
            return resultArray;
        }
    }

    for (TIntermNode *&argument : *aggregate->getSequence())
    {
        TIntermConstantUnion *argumentConstant   = argument->getAsConstantUnion();
        size_t argumentSize                      = argumentConstant->getType().getObjectSize();
        const TConstantUnion *argumentUnionArray = argumentConstant->getUnionArrayPointer();
        for (size_t i = 0u; i < argumentSize; ++i)
        {
            if (resultIndex >= resultSize)
                break;
            resultArray[resultIndex].cast(basicType, argumentUnionArray[i]);
            ++resultIndex;
        }
    }
    ASSERT(resultIndex == resultSize);
    return resultArray;
}

// static
TConstantUnion *TIntermConstantUnion::FoldAggregateBuiltIn(TIntermAggregate *aggregate,
                                                           TDiagnostics *diagnostics)
{
    TOperator op = aggregate->getOp();
    TIntermSequence *sequence = aggregate->getSequence();
    unsigned int paramsCount = static_cast<unsigned int>(sequence->size());
    std::vector<const TConstantUnion *> unionArrays(paramsCount);
    std::vector<size_t> objectSizes(paramsCount);
    size_t maxObjectSize = 0;
    TBasicType basicType = EbtVoid;
    TSourceLoc loc;
    for (unsigned int i = 0; i < paramsCount; i++)
    {
        TIntermConstantUnion *paramConstant = (*sequence)[i]->getAsConstantUnion();
        ASSERT(paramConstant != nullptr); // Should be checked already.

        if (i == 0)
        {
            basicType = paramConstant->getType().getBasicType();
            loc = paramConstant->getLine();
        }
        unionArrays[i] = paramConstant->getUnionArrayPointer();
        objectSizes[i] = paramConstant->getType().getObjectSize();
        if (objectSizes[i] > maxObjectSize)
            maxObjectSize = objectSizes[i];
    }

    if (!(*sequence)[0]->getAsTyped()->isMatrix() && aggregate->getOp() != EOpOuterProduct)
    {
        for (unsigned int i = 0; i < paramsCount; i++)
            if (objectSizes[i] != maxObjectSize)
                unionArrays[i] = Vectorize(*unionArrays[i], maxObjectSize);
    }

    TConstantUnion *resultArray = nullptr;
    if (paramsCount == 2)
    {
        //
        // Binary built-in
        //
        switch (op)
        {
            case EOpAtan:
            {
                ASSERT(basicType == EbtFloat);
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    float y = unionArrays[0][i].getFConst();
                    float x = unionArrays[1][i].getFConst();
                    // Results are undefined if x and y are both 0.
                    if (x == 0.0f && y == 0.0f)
                        UndefinedConstantFoldingError(loc, op, basicType, diagnostics,
                                                      &resultArray[i]);
                    else
                        resultArray[i].setFConst(atan2f(y, x));
                }
                break;
            }

            case EOpPow:
            {
                ASSERT(basicType == EbtFloat);
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    float x = unionArrays[0][i].getFConst();
                    float y = unionArrays[1][i].getFConst();
                    // Results are undefined if x < 0.
                    // Results are undefined if x = 0 and y <= 0.
                    if (x < 0.0f)
                        UndefinedConstantFoldingError(loc, op, basicType, diagnostics,
                                                      &resultArray[i]);
                    else if (x == 0.0f && y <= 0.0f)
                        UndefinedConstantFoldingError(loc, op, basicType, diagnostics,
                                                      &resultArray[i]);
                    else
                        resultArray[i].setFConst(powf(x, y));
                }
                break;
            }

            case EOpMod:
            {
                ASSERT(basicType == EbtFloat);
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    float x = unionArrays[0][i].getFConst();
                    float y = unionArrays[1][i].getFConst();
                    resultArray[i].setFConst(x - y * floorf(x / y));
                }
                break;
            }

            case EOpMin:
            {
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    switch (basicType)
                    {
                        case EbtFloat:
                            resultArray[i].setFConst(std::min(unionArrays[0][i].getFConst(),
                                                              unionArrays[1][i].getFConst()));
                            break;
                        case EbtInt:
                            resultArray[i].setIConst(std::min(unionArrays[0][i].getIConst(),
                                                              unionArrays[1][i].getIConst()));
                            break;
                        case EbtUInt:
                            resultArray[i].setUConst(std::min(unionArrays[0][i].getUConst(),
                                                              unionArrays[1][i].getUConst()));
                            break;
                        default:
                            UNREACHABLE();
                            break;
                    }
                }
                break;
            }

            case EOpMax:
            {
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    switch (basicType)
                    {
                        case EbtFloat:
                            resultArray[i].setFConst(std::max(unionArrays[0][i].getFConst(),
                                                              unionArrays[1][i].getFConst()));
                            break;
                        case EbtInt:
                            resultArray[i].setIConst(std::max(unionArrays[0][i].getIConst(),
                                                              unionArrays[1][i].getIConst()));
                            break;
                        case EbtUInt:
                            resultArray[i].setUConst(std::max(unionArrays[0][i].getUConst(),
                                                              unionArrays[1][i].getUConst()));
                            break;
                        default:
                            UNREACHABLE();
                            break;
                    }
                }
                break;
            }

            case EOpStep:
            {
                ASSERT(basicType == EbtFloat);
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                    resultArray[i].setFConst(
                        unionArrays[1][i].getFConst() < unionArrays[0][i].getFConst() ? 0.0f
                                                                                      : 1.0f);
                break;
            }

            case EOpLessThan:
            {
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    switch (basicType)
                    {
                        case EbtFloat:
                            resultArray[i].setBConst(unionArrays[0][i].getFConst() <
                                                     unionArrays[1][i].getFConst());
                            break;
                        case EbtInt:
                            resultArray[i].setBConst(unionArrays[0][i].getIConst() <
                                                     unionArrays[1][i].getIConst());
                            break;
                        case EbtUInt:
                            resultArray[i].setBConst(unionArrays[0][i].getUConst() <
                                                     unionArrays[1][i].getUConst());
                            break;
                        default:
                            UNREACHABLE();
                            break;
                    }
                }
                break;
            }

            case EOpLessThanEqual:
            {
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    switch (basicType)
                    {
                        case EbtFloat:
                            resultArray[i].setBConst(unionArrays[0][i].getFConst() <=
                                                     unionArrays[1][i].getFConst());
                            break;
                        case EbtInt:
                            resultArray[i].setBConst(unionArrays[0][i].getIConst() <=
                                                     unionArrays[1][i].getIConst());
                            break;
                        case EbtUInt:
                            resultArray[i].setBConst(unionArrays[0][i].getUConst() <=
                                                     unionArrays[1][i].getUConst());
                            break;
                        default:
                            UNREACHABLE();
                            break;
                    }
                }
                break;
            }

            case EOpGreaterThan:
            {
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    switch (basicType)
                    {
                        case EbtFloat:
                            resultArray[i].setBConst(unionArrays[0][i].getFConst() >
                                                     unionArrays[1][i].getFConst());
                            break;
                        case EbtInt:
                            resultArray[i].setBConst(unionArrays[0][i].getIConst() >
                                                     unionArrays[1][i].getIConst());
                            break;
                        case EbtUInt:
                            resultArray[i].setBConst(unionArrays[0][i].getUConst() >
                                                     unionArrays[1][i].getUConst());
                            break;
                        default:
                            UNREACHABLE();
                            break;
                    }
                }
                break;
            }
            case EOpGreaterThanEqual:
            {
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    switch (basicType)
                    {
                        case EbtFloat:
                            resultArray[i].setBConst(unionArrays[0][i].getFConst() >=
                                                     unionArrays[1][i].getFConst());
                            break;
                        case EbtInt:
                            resultArray[i].setBConst(unionArrays[0][i].getIConst() >=
                                                     unionArrays[1][i].getIConst());
                            break;
                        case EbtUInt:
                            resultArray[i].setBConst(unionArrays[0][i].getUConst() >=
                                                     unionArrays[1][i].getUConst());
                            break;
                        default:
                            UNREACHABLE();
                            break;
                    }
                }
            }
            break;

            case EOpVectorEqual:
            {
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    switch (basicType)
                    {
                        case EbtFloat:
                            resultArray[i].setBConst(unionArrays[0][i].getFConst() ==
                                                     unionArrays[1][i].getFConst());
                            break;
                        case EbtInt:
                            resultArray[i].setBConst(unionArrays[0][i].getIConst() ==
                                                     unionArrays[1][i].getIConst());
                            break;
                        case EbtUInt:
                            resultArray[i].setBConst(unionArrays[0][i].getUConst() ==
                                                     unionArrays[1][i].getUConst());
                            break;
                        case EbtBool:
                            resultArray[i].setBConst(unionArrays[0][i].getBConst() ==
                                                     unionArrays[1][i].getBConst());
                            break;
                        default:
                            UNREACHABLE();
                            break;
                    }
                }
                break;
            }

            case EOpVectorNotEqual:
            {
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    switch (basicType)
                    {
                        case EbtFloat:
                            resultArray[i].setBConst(unionArrays[0][i].getFConst() !=
                                                     unionArrays[1][i].getFConst());
                            break;
                        case EbtInt:
                            resultArray[i].setBConst(unionArrays[0][i].getIConst() !=
                                                     unionArrays[1][i].getIConst());
                            break;
                        case EbtUInt:
                            resultArray[i].setBConst(unionArrays[0][i].getUConst() !=
                                                     unionArrays[1][i].getUConst());
                            break;
                        case EbtBool:
                            resultArray[i].setBConst(unionArrays[0][i].getBConst() !=
                                                     unionArrays[1][i].getBConst());
                            break;
                        default:
                            UNREACHABLE();
                            break;
                    }
                }
                break;
            }

            case EOpDistance:
            {
                ASSERT(basicType == EbtFloat);
                TConstantUnion *distanceArray = new TConstantUnion[maxObjectSize];
                resultArray                   = new TConstantUnion();
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    float x = unionArrays[0][i].getFConst();
                    float y = unionArrays[1][i].getFConst();
                    distanceArray[i].setFConst(x - y);
                }
                resultArray->setFConst(VectorLength(distanceArray, maxObjectSize));
                break;
            }

            case EOpDot:
                ASSERT(basicType == EbtFloat);
                resultArray = new TConstantUnion();
                resultArray->setFConst(
                    VectorDotProduct(unionArrays[0], unionArrays[1], maxObjectSize));
                break;

            case EOpCross:
            {
                ASSERT(basicType == EbtFloat && maxObjectSize == 3);
                resultArray = new TConstantUnion[maxObjectSize];
                float x0    = unionArrays[0][0].getFConst();
                float x1    = unionArrays[0][1].getFConst();
                float x2    = unionArrays[0][2].getFConst();
                float y0    = unionArrays[1][0].getFConst();
                float y1    = unionArrays[1][1].getFConst();
                float y2    = unionArrays[1][2].getFConst();
                resultArray[0].setFConst(x1 * y2 - y1 * x2);
                resultArray[1].setFConst(x2 * y0 - y2 * x0);
                resultArray[2].setFConst(x0 * y1 - y0 * x1);
                break;
            }

            case EOpReflect:
            {
                ASSERT(basicType == EbtFloat);
                // genType reflect (genType I, genType N) :
                //     For the incident vector I and surface orientation N, returns the reflection
                //     direction:
                //     I - 2 * dot(N, I) * N.
                resultArray      = new TConstantUnion[maxObjectSize];
                float dotProduct = VectorDotProduct(unionArrays[1], unionArrays[0], maxObjectSize);
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    float result = unionArrays[0][i].getFConst() -
                                   2.0f * dotProduct * unionArrays[1][i].getFConst();
                    resultArray[i].setFConst(result);
                }
                break;
            }

            case EOpMul:
            {
                ASSERT(basicType == EbtFloat && (*sequence)[0]->getAsTyped()->isMatrix() &&
                       (*sequence)[1]->getAsTyped()->isMatrix());
                // Perform component-wise matrix multiplication.
                resultArray = new TConstantUnion[maxObjectSize];
                int size    = (*sequence)[0]->getAsTyped()->getNominalSize();
                angle::Matrix<float> result =
                    GetMatrix(unionArrays[0], size).compMult(GetMatrix(unionArrays[1], size));
                SetUnionArrayFromMatrix(result, resultArray);
                break;
            }

            case EOpOuterProduct:
            {
                ASSERT(basicType == EbtFloat);
                size_t numRows = (*sequence)[0]->getAsTyped()->getType().getObjectSize();
                size_t numCols = (*sequence)[1]->getAsTyped()->getType().getObjectSize();
                resultArray    = new TConstantUnion[numRows * numCols];
                angle::Matrix<float> result =
                    GetMatrix(unionArrays[0], static_cast<int>(numRows), 1)
                        .outerProduct(GetMatrix(unionArrays[1], 1, static_cast<int>(numCols)));
                SetUnionArrayFromMatrix(result, resultArray);
                break;
            }

            default:
                UNREACHABLE();
                // TODO: Add constant folding support for other built-in operations that take 2
                // parameters and not handled above.
                return nullptr;
        }
    }
    else if (paramsCount == 3)
    {
        //
        // Ternary built-in
        //
        switch (op)
        {
            case EOpClamp:
            {
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    switch (basicType)
                    {
                        case EbtFloat:
                        {
                            float x   = unionArrays[0][i].getFConst();
                            float min = unionArrays[1][i].getFConst();
                            float max = unionArrays[2][i].getFConst();
                            // Results are undefined if min > max.
                            if (min > max)
                                UndefinedConstantFoldingError(loc, op, basicType, diagnostics,
                                                              &resultArray[i]);
                            else
                                resultArray[i].setFConst(gl::clamp(x, min, max));
                            break;
                        }

                        case EbtInt:
                        {
                            int x   = unionArrays[0][i].getIConst();
                            int min = unionArrays[1][i].getIConst();
                            int max = unionArrays[2][i].getIConst();
                            // Results are undefined if min > max.
                            if (min > max)
                                UndefinedConstantFoldingError(loc, op, basicType, diagnostics,
                                                              &resultArray[i]);
                            else
                                resultArray[i].setIConst(gl::clamp(x, min, max));
                            break;
                        }
                        case EbtUInt:
                        {
                            unsigned int x   = unionArrays[0][i].getUConst();
                            unsigned int min = unionArrays[1][i].getUConst();
                            unsigned int max = unionArrays[2][i].getUConst();
                            // Results are undefined if min > max.
                            if (min > max)
                                UndefinedConstantFoldingError(loc, op, basicType, diagnostics,
                                                              &resultArray[i]);
                            else
                                resultArray[i].setUConst(gl::clamp(x, min, max));
                            break;
                        }
                        default:
                            UNREACHABLE();
                            break;
                    }
                }
                break;
            }

            case EOpMix:
            {
                ASSERT(basicType == EbtFloat);
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    float x         = unionArrays[0][i].getFConst();
                    float y         = unionArrays[1][i].getFConst();
                    TBasicType type = (*sequence)[2]->getAsTyped()->getType().getBasicType();
                    if (type == EbtFloat)
                    {
                        // Returns the linear blend of x and y, i.e., x * (1 - a) + y * a.
                        float a = unionArrays[2][i].getFConst();
                        resultArray[i].setFConst(x * (1.0f - a) + y * a);
                    }
                    else  // 3rd parameter is EbtBool
                    {
                        ASSERT(type == EbtBool);
                        // Selects which vector each returned component comes from.
                        // For a component of a that is false, the corresponding component of x is
                        // returned.
                        // For a component of a that is true, the corresponding component of y is
                        // returned.
                        bool a = unionArrays[2][i].getBConst();
                        resultArray[i].setFConst(a ? y : x);
                    }
                }
                break;
            }

            case EOpSmoothStep:
            {
                ASSERT(basicType == EbtFloat);
                resultArray = new TConstantUnion[maxObjectSize];
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    float edge0 = unionArrays[0][i].getFConst();
                    float edge1 = unionArrays[1][i].getFConst();
                    float x     = unionArrays[2][i].getFConst();
                    // Results are undefined if edge0 >= edge1.
                    if (edge0 >= edge1)
                    {
                        UndefinedConstantFoldingError(loc, op, basicType, diagnostics,
                                                      &resultArray[i]);
                    }
                    else
                    {
                        // Returns 0.0 if x <= edge0 and 1.0 if x >= edge1 and performs smooth
                        // Hermite interpolation between 0 and 1 when edge0 < x < edge1.
                        float t = gl::clamp((x - edge0) / (edge1 - edge0), 0.0f, 1.0f);
                        resultArray[i].setFConst(t * t * (3.0f - 2.0f * t));
                    }
                }
                break;
            }

            case EOpFaceForward:
            {
                ASSERT(basicType == EbtFloat);
                // genType faceforward(genType N, genType I, genType Nref) :
                //     If dot(Nref, I) < 0 return N, otherwise return -N.
                resultArray      = new TConstantUnion[maxObjectSize];
                float dotProduct = VectorDotProduct(unionArrays[2], unionArrays[1], maxObjectSize);
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    if (dotProduct < 0)
                        resultArray[i].setFConst(unionArrays[0][i].getFConst());
                    else
                        resultArray[i].setFConst(-unionArrays[0][i].getFConst());
                }
                break;
            }

            case EOpRefract:
            {
                ASSERT(basicType == EbtFloat);
                // genType refract(genType I, genType N, float eta) :
                //     For the incident vector I and surface normal N, and the ratio of indices of
                //     refraction eta,
                //     return the refraction vector. The result is computed by
                //         k = 1.0 - eta * eta * (1.0 - dot(N, I) * dot(N, I))
                //         if (k < 0.0)
                //             return genType(0.0)
                //         else
                //             return eta * I - (eta * dot(N, I) + sqrt(k)) * N
                resultArray      = new TConstantUnion[maxObjectSize];
                float dotProduct = VectorDotProduct(unionArrays[1], unionArrays[0], maxObjectSize);
                for (size_t i = 0; i < maxObjectSize; i++)
                {
                    float eta = unionArrays[2][i].getFConst();
                    float k   = 1.0f - eta * eta * (1.0f - dotProduct * dotProduct);
                    if (k < 0.0f)
                        resultArray[i].setFConst(0.0f);
                    else
                        resultArray[i].setFConst(eta * unionArrays[0][i].getFConst() -
                                                 (eta * dotProduct + sqrtf(k)) *
                                                     unionArrays[1][i].getFConst());
                }
                break;
            }

            default:
                UNREACHABLE();
                // TODO: Add constant folding support for other built-in operations that take 3
                // parameters and not handled above.
                return nullptr;
        }
    }
    return resultArray;
}

// static
TString TIntermTraverser::hash(const TString &name, ShHashFunction64 hashFunction)
{
    if (hashFunction == NULL || name.empty())
        return name;
    khronos_uint64_t number = (*hashFunction)(name.c_str(), name.length());
    TStringStream stream;
    stream << HASHED_NAME_PREFIX << std::hex << number;
    TString hashedName = stream.str();
    return hashedName;
}

void TIntermTraverser::updateTree()
{
    for (size_t ii = 0; ii < mInsertions.size(); ++ii)
    {
        const NodeInsertMultipleEntry &insertion = mInsertions[ii];
        ASSERT(insertion.parent);
        if (!insertion.insertionsAfter.empty())
        {
            bool inserted = insertion.parent->insertChildNodes(insertion.position + 1,
                                                               insertion.insertionsAfter);
            ASSERT(inserted);
            UNUSED_ASSERTION_VARIABLE(inserted);
        }
        if (!insertion.insertionsBefore.empty())
        {
            bool inserted =
                insertion.parent->insertChildNodes(insertion.position, insertion.insertionsBefore);
            ASSERT(inserted);
            UNUSED_ASSERTION_VARIABLE(inserted);
        }
    }
    for (size_t ii = 0; ii < mReplacements.size(); ++ii)
    {
        const NodeUpdateEntry &replacement = mReplacements[ii];
        ASSERT(replacement.parent);
        bool replaced = replacement.parent->replaceChildNode(
            replacement.original, replacement.replacement);
        ASSERT(replaced);
        UNUSED_ASSERTION_VARIABLE(replaced);

        if (!replacement.originalBecomesChildOfReplacement)
        {
            // In AST traversing, a parent is visited before its children.
            // After we replace a node, if its immediate child is to
            // be replaced, we need to make sure we don't update the replaced
            // node; instead, we update the replacement node.
            for (size_t jj = ii + 1; jj < mReplacements.size(); ++jj)
            {
                NodeUpdateEntry &replacement2 = mReplacements[jj];
                if (replacement2.parent == replacement.original)
                    replacement2.parent = replacement.replacement;
            }
        }
    }
    for (size_t ii = 0; ii < mMultiReplacements.size(); ++ii)
    {
        const NodeReplaceWithMultipleEntry &replacement = mMultiReplacements[ii];
        ASSERT(replacement.parent);
        bool replaced = replacement.parent->replaceChildNodeWithMultiple(
            replacement.original, replacement.replacements);
        ASSERT(replaced);
        UNUSED_ASSERTION_VARIABLE(replaced);
    }

    clearReplacementQueue();
}

void TIntermTraverser::clearReplacementQueue()
{
    mReplacements.clear();
    mMultiReplacements.clear();
    mInsertions.clear();
}

void TIntermTraverser::queueReplacement(TIntermNode *original,
                                        TIntermNode *replacement,
                                        OriginalNode originalStatus)
{
    queueReplacementWithParent(getParentNode(), original, replacement, originalStatus);
}

void TIntermTraverser::queueReplacementWithParent(TIntermNode *parent,
                                                  TIntermNode *original,
                                                  TIntermNode *replacement,
                                                  OriginalNode originalStatus)
{
    bool originalBecomesChild = (originalStatus == OriginalNode::BECOMES_CHILD);
    mReplacements.push_back(NodeUpdateEntry(parent, original, replacement, originalBecomesChild));
}