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[ConstantRange] Simplify makeGNWR implementation; NFC
Compute results in more direct ways, avoid subset intersect operations. Extract the core code for computing mul nowrap ranges into separate static functions, so they can be reused. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@360189 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nikita Popov
parent
b81da4406f
commit
91e043f327
@ -180,132 +180,96 @@ bool ConstantRange::getEquivalentICmp(CmpInst::Predicate &Pred,
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return Success;
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}
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/// Exact mul nuw region for single element RHS.
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static ConstantRange makeExactMulNUWRegion(const APInt &V) {
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unsigned BitWidth = V.getBitWidth();
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if (V == 0)
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return ConstantRange::getFull(V.getBitWidth());
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return ConstantRange::getNonEmpty(
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APIntOps::RoundingUDiv(APInt::getMinValue(BitWidth), V,
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APInt::Rounding::UP),
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APIntOps::RoundingUDiv(APInt::getMaxValue(BitWidth), V,
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APInt::Rounding::DOWN) + 1);
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}
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/// Exact mul nsw region for single element RHS.
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static ConstantRange makeExactMulNSWRegion(const APInt &V) {
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// Handle special case for 0, -1 and 1. See the last for reason why we
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// specialize -1 and 1.
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unsigned BitWidth = V.getBitWidth();
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if (V == 0 || V.isOneValue())
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return ConstantRange::getFull(BitWidth);
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APInt MinValue = APInt::getSignedMinValue(BitWidth);
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APInt MaxValue = APInt::getSignedMaxValue(BitWidth);
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// e.g. Returning [-127, 127], represented as [-127, -128).
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if (V.isAllOnesValue())
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return ConstantRange(-MaxValue, MinValue);
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APInt Lower, Upper;
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if (V.isNegative()) {
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Lower = APIntOps::RoundingSDiv(MaxValue, V, APInt::Rounding::UP);
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Upper = APIntOps::RoundingSDiv(MinValue, V, APInt::Rounding::DOWN);
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} else {
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Lower = APIntOps::RoundingSDiv(MinValue, V, APInt::Rounding::UP);
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Upper = APIntOps::RoundingSDiv(MaxValue, V, APInt::Rounding::DOWN);
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}
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// ConstantRange ctor take a half inclusive interval [Lower, Upper + 1).
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// Upper + 1 is guaranteed not to overflow, because |divisor| > 1. 0, -1,
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// and 1 are already handled as special cases.
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return ConstantRange(Lower, Upper + 1);
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}
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ConstantRange
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ConstantRange::makeGuaranteedNoWrapRegion(Instruction::BinaryOps BinOp,
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const ConstantRange &Other,
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unsigned NoWrapKind) {
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using OBO = OverflowingBinaryOperator;
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// Computes the intersection of CR0 and CR1. It is different from
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// intersectWith in that the ConstantRange returned will only contain elements
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// in both CR0 and CR1 (i.e. SubsetIntersect(X, Y) is a *subset*, proper or
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// not, of both X and Y).
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auto SubsetIntersect =
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[](const ConstantRange &CR0, const ConstantRange &CR1) {
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return CR0.inverse().unionWith(CR1.inverse()).inverse();
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};
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assert(Instruction::isBinaryOp(BinOp) && "Binary operators only!");
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assert((NoWrapKind == OBO::NoSignedWrap ||
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NoWrapKind == OBO::NoUnsignedWrap) &&
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"NoWrapKind invalid!");
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bool Unsigned = NoWrapKind == OBO::NoUnsignedWrap;
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unsigned BitWidth = Other.getBitWidth();
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ConstantRange Result(BitWidth, /* full */ true);
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switch (BinOp) {
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default:
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// Conservative answer: empty set
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return getEmpty(BitWidth);
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case Instruction::Add:
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if (auto *C = Other.getSingleElement())
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if (C->isNullValue())
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// Full set: nothing signed / unsigned wraps when added to 0.
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return getFull(BitWidth);
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if (NoWrapKind == OBO::NoUnsignedWrap)
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return ConstantRange(APInt::getNullValue(BitWidth),
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-Other.getUnsignedMax());
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if (NoWrapKind == OBO::NoSignedWrap) {
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const APInt &SignedMin = Other.getSignedMin();
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const APInt &SignedMax = Other.getSignedMax();
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if (SignedMax.isStrictlyPositive())
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Result = SubsetIntersect(
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Result,
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ConstantRange(APInt::getSignedMinValue(BitWidth),
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APInt::getSignedMinValue(BitWidth) - SignedMax));
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if (SignedMin.isNegative())
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Result = SubsetIntersect(
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Result,
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ConstantRange(APInt::getSignedMinValue(BitWidth) - SignedMin,
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APInt::getSignedMinValue(BitWidth)));
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}
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return Result;
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case Instruction::Sub:
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if (auto *C = Other.getSingleElement())
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if (C->isNullValue())
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// Full set: nothing signed / unsigned wraps when subtracting 0.
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return getFull(BitWidth);
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if (NoWrapKind == OBO::NoUnsignedWrap)
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return ConstantRange(Other.getUnsignedMax(),
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APInt::getMinValue(BitWidth));
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if (NoWrapKind == OBO::NoSignedWrap) {
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const APInt &SignedMin = Other.getSignedMin();
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const APInt &SignedMax = Other.getSignedMax();
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if (SignedMax.isStrictlyPositive())
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Result = SubsetIntersect(
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Result,
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ConstantRange(APInt::getSignedMinValue(BitWidth) + SignedMax,
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APInt::getSignedMinValue(BitWidth)));
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if (SignedMin.isNegative())
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Result = SubsetIntersect(
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Result,
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ConstantRange(APInt::getSignedMinValue(BitWidth),
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APInt::getSignedMinValue(BitWidth) + SignedMin));
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}
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return Result;
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case Instruction::Mul: {
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// Equivalent to calling makeGuaranteedNoWrapRegion() on [V, V+1).
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const bool Unsigned = NoWrapKind == OBO::NoUnsignedWrap;
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const auto makeSingleValueRegion = [Unsigned,
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BitWidth](APInt V) -> ConstantRange {
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// Handle special case for 0, -1 and 1. See the last for reason why we
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// specialize -1 and 1.
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if (V == 0 || V.isOneValue())
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return getFull(BitWidth);
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APInt MinValue, MaxValue;
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if (Unsigned) {
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MinValue = APInt::getMinValue(BitWidth);
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MaxValue = APInt::getMaxValue(BitWidth);
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} else {
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MinValue = APInt::getSignedMinValue(BitWidth);
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MaxValue = APInt::getSignedMaxValue(BitWidth);
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}
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// e.g. Returning [-127, 127], represented as [-127, -128).
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if (!Unsigned && V.isAllOnesValue())
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return ConstantRange(-MaxValue, MinValue);
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APInt Lower, Upper;
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if (!Unsigned && V.isNegative()) {
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Lower = APIntOps::RoundingSDiv(MaxValue, V, APInt::Rounding::UP);
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Upper = APIntOps::RoundingSDiv(MinValue, V, APInt::Rounding::DOWN);
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} else if (Unsigned) {
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Lower = APIntOps::RoundingUDiv(MinValue, V, APInt::Rounding::UP);
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Upper = APIntOps::RoundingUDiv(MaxValue, V, APInt::Rounding::DOWN);
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} else {
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Lower = APIntOps::RoundingSDiv(MinValue, V, APInt::Rounding::UP);
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Upper = APIntOps::RoundingSDiv(MaxValue, V, APInt::Rounding::DOWN);
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}
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// ConstantRange ctor take a half inclusive interval [Lower, Upper + 1).
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// Upper + 1 is guanranteed not to overflow, because |divisor| > 1. 0, -1,
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// and 1 are already handled as special cases.
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return ConstantRange(Lower, Upper + 1);
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};
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case Instruction::Add: {
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if (Unsigned)
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return makeSingleValueRegion(Other.getUnsignedMax());
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return getNonEmpty(APInt::getNullValue(BitWidth),
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-Other.getUnsignedMax());
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return SubsetIntersect(makeSingleValueRegion(Other.getSignedMin()),
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makeSingleValueRegion(Other.getSignedMax()));
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APInt SignedMinVal = APInt::getSignedMinValue(BitWidth);
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APInt SMin = Other.getSignedMin(), SMax = Other.getSignedMax();
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return getNonEmpty(
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SMin.isNegative() ? SignedMinVal - SMin : SignedMinVal,
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SMax.isStrictlyPositive() ? SignedMinVal - SMax : SignedMinVal);
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}
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case Instruction::Sub: {
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if (Unsigned)
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return getNonEmpty(Other.getUnsignedMax(), APInt::getMinValue(BitWidth));
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APInt SignedMinVal = APInt::getSignedMinValue(BitWidth);
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APInt SMin = Other.getSignedMin(), SMax = Other.getSignedMax();
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return getNonEmpty(
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SMax.isStrictlyPositive() ? SignedMinVal + SMax : SignedMinVal,
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SMin.isNegative() ? SignedMinVal + SMin : SignedMinVal);
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}
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case Instruction::Mul:
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if (Unsigned)
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return makeExactMulNUWRegion(Other.getUnsignedMax());
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return makeExactMulNSWRegion(Other.getSignedMin())
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.intersectWith(makeExactMulNSWRegion(Other.getSignedMax()));
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}
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}
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