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llvm-mirror/lib/IR/ConstantRange.cpp
Nikita Popov 54bcf692a3 [ConstantRange] Add sdiv() support 
The implementation is conceptually simple: We separate the LHS and
RHS into positive and negative components and then also compute the
positive and negative components of the result, taking into account
that e.g. only pos/pos and neg/neg will give a positive result.

However, there's one significant complication: SignedMin / -1 is UB
for sdiv, and we can't just ignore it, because the APInt result of
SignedMin would break the sign segregation. Instead we drop SignedMin
or -1 from the corresponding ranges, taking into account some edge
cases with wrapped ranges.

Because of the sign segregation, the implementation ends up being
nearly fully precise even for wrapped ranges (the remaining
imprecision is due to ranges that are both signed and unsigned
wrapping and are divided by a trivial divisor like 1). This means
that the testing cannot just check the signed envelope as we
usually do. Instead we collect all possible results in a bitvector
and construct a better sign wrapped range (than the full envelope).

Differential Revision: https://reviews.llvm.org/D61238

llvm-svn: 362430
2019-06-03 18:19:54 +00:00

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//===- ConstantRange.cpp - ConstantRange implementation -------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Represent a range of possible values that may occur when the program is run
// for an integral value. This keeps track of a lower and upper bound for the
// constant, which MAY wrap around the end of the numeric range. To do this, it
// keeps track of a [lower, upper) bound, which specifies an interval just like
// STL iterators. When used with boolean values, the following are important
// ranges (other integral ranges use min/max values for special range values):
//
// [F, F) = {} = Empty set
// [T, F) = {T}
// [F, T) = {F}
// [T, T) = {F, T} = Full set
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/APInt.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Operator.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
using namespace llvm;
ConstantRange::ConstantRange(uint32_t BitWidth, bool Full)
: Lower(Full ? APInt::getMaxValue(BitWidth) : APInt::getMinValue(BitWidth)),
Upper(Lower) {}
ConstantRange::ConstantRange(APInt V)
: Lower(std::move(V)), Upper(Lower + 1) {}
ConstantRange::ConstantRange(APInt L, APInt U)
: Lower(std::move(L)), Upper(std::move(U)) {
assert(Lower.getBitWidth() == Upper.getBitWidth() &&
"ConstantRange with unequal bit widths");
assert((Lower != Upper || (Lower.isMaxValue() || Lower.isMinValue())) &&
"Lower == Upper, but they aren't min or max value!");
}
ConstantRange ConstantRange::fromKnownBits(const KnownBits &Known,
bool IsSigned) {
assert(!Known.hasConflict() && "Expected valid KnownBits");
if (Known.isUnknown())
return getFull(Known.getBitWidth());
// For unsigned ranges, or signed ranges with known sign bit, create a simple
// range between the smallest and largest possible value.
if (!IsSigned || Known.isNegative() || Known.isNonNegative())
return ConstantRange(Known.One, ~Known.Zero + 1);
// If we don't know the sign bit, pick the lower bound as a negative number
// and the upper bound as a non-negative one.
APInt Lower = Known.One, Upper = ~Known.Zero;
Lower.setSignBit();
Upper.clearSignBit();
return ConstantRange(Lower, Upper + 1);
}
ConstantRange ConstantRange::makeAllowedICmpRegion(CmpInst::Predicate Pred,
const ConstantRange &CR) {
if (CR.isEmptySet())
return CR;
uint32_t W = CR.getBitWidth();
switch (Pred) {
default:
llvm_unreachable("Invalid ICmp predicate to makeAllowedICmpRegion()");
case CmpInst::ICMP_EQ:
return CR;
case CmpInst::ICMP_NE:
if (CR.isSingleElement())
return ConstantRange(CR.getUpper(), CR.getLower());
return getFull(W);
case CmpInst::ICMP_ULT: {
APInt UMax(CR.getUnsignedMax());
if (UMax.isMinValue())
return getEmpty(W);
return ConstantRange(APInt::getMinValue(W), std::move(UMax));
}
case CmpInst::ICMP_SLT: {
APInt SMax(CR.getSignedMax());
if (SMax.isMinSignedValue())
return getEmpty(W);
return ConstantRange(APInt::getSignedMinValue(W), std::move(SMax));
}
case CmpInst::ICMP_ULE:
return getNonEmpty(APInt::getMinValue(W), CR.getUnsignedMax() + 1);
case CmpInst::ICMP_SLE:
return getNonEmpty(APInt::getSignedMinValue(W), CR.getSignedMax() + 1);
case CmpInst::ICMP_UGT: {
APInt UMin(CR.getUnsignedMin());
if (UMin.isMaxValue())
return getEmpty(W);
return ConstantRange(std::move(UMin) + 1, APInt::getNullValue(W));
}
case CmpInst::ICMP_SGT: {
APInt SMin(CR.getSignedMin());
if (SMin.isMaxSignedValue())
return getEmpty(W);
return ConstantRange(std::move(SMin) + 1, APInt::getSignedMinValue(W));
}
case CmpInst::ICMP_UGE:
return getNonEmpty(CR.getUnsignedMin(), APInt::getNullValue(W));
case CmpInst::ICMP_SGE:
return getNonEmpty(CR.getSignedMin(), APInt::getSignedMinValue(W));
}
}
ConstantRange ConstantRange::makeSatisfyingICmpRegion(CmpInst::Predicate Pred,
const ConstantRange &CR) {
// Follows from De-Morgan's laws:
//
// ~(~A union ~B) == A intersect B.
//
return makeAllowedICmpRegion(CmpInst::getInversePredicate(Pred), CR)
.inverse();
}
ConstantRange ConstantRange::makeExactICmpRegion(CmpInst::Predicate Pred,
const APInt &C) {
// Computes the exact range that is equal to both the constant ranges returned
// by makeAllowedICmpRegion and makeSatisfyingICmpRegion. This is always true
// when RHS is a singleton such as an APInt and so the assert is valid.
// However for non-singleton RHS, for example ult [2,5) makeAllowedICmpRegion
// returns [0,4) but makeSatisfyICmpRegion returns [0,2).
//
assert(makeAllowedICmpRegion(Pred, C) == makeSatisfyingICmpRegion(Pred, C));
return makeAllowedICmpRegion(Pred, C);
}
bool ConstantRange::getEquivalentICmp(CmpInst::Predicate &Pred,
APInt &RHS) const {
bool Success = false;
if (isFullSet() || isEmptySet()) {
Pred = isEmptySet() ? CmpInst::ICMP_ULT : CmpInst::ICMP_UGE;
RHS = APInt(getBitWidth(), 0);
Success = true;
} else if (auto *OnlyElt = getSingleElement()) {
Pred = CmpInst::ICMP_EQ;
RHS = *OnlyElt;
Success = true;
} else if (auto *OnlyMissingElt = getSingleMissingElement()) {
Pred = CmpInst::ICMP_NE;
RHS = *OnlyMissingElt;
Success = true;
} else if (getLower().isMinSignedValue() || getLower().isMinValue()) {
Pred =
getLower().isMinSignedValue() ? CmpInst::ICMP_SLT : CmpInst::ICMP_ULT;
RHS = getUpper();
Success = true;
} else if (getUpper().isMinSignedValue() || getUpper().isMinValue()) {
Pred =
getUpper().isMinSignedValue() ? CmpInst::ICMP_SGE : CmpInst::ICMP_UGE;
RHS = getLower();
Success = true;
}
assert((!Success || ConstantRange::makeExactICmpRegion(Pred, RHS) == *this) &&
"Bad result!");
return Success;
}
/// Exact mul nuw region for single element RHS.
static ConstantRange makeExactMulNUWRegion(const APInt &V) {
unsigned BitWidth = V.getBitWidth();
if (V == 0)
return ConstantRange::getFull(V.getBitWidth());
return ConstantRange::getNonEmpty(
APIntOps::RoundingUDiv(APInt::getMinValue(BitWidth), V,
APInt::Rounding::UP),
APIntOps::RoundingUDiv(APInt::getMaxValue(BitWidth), V,
APInt::Rounding::DOWN) + 1);
}
/// Exact mul nsw region for single element RHS.
static ConstantRange makeExactMulNSWRegion(const APInt &V) {
// Handle special case for 0, -1 and 1. See the last for reason why we
// specialize -1 and 1.
unsigned BitWidth = V.getBitWidth();
if (V == 0 || V.isOneValue())
return ConstantRange::getFull(BitWidth);
APInt MinValue = APInt::getSignedMinValue(BitWidth);
APInt MaxValue = APInt::getSignedMaxValue(BitWidth);
// e.g. Returning [-127, 127], represented as [-127, -128).
if (V.isAllOnesValue())
return ConstantRange(-MaxValue, MinValue);
APInt Lower, Upper;
if (V.isNegative()) {
Lower = APIntOps::RoundingSDiv(MaxValue, V, APInt::Rounding::UP);
Upper = APIntOps::RoundingSDiv(MinValue, V, APInt::Rounding::DOWN);
} else {
Lower = APIntOps::RoundingSDiv(MinValue, V, APInt::Rounding::UP);
Upper = APIntOps::RoundingSDiv(MaxValue, V, APInt::Rounding::DOWN);
}
// ConstantRange ctor take a half inclusive interval [Lower, Upper + 1).
// Upper + 1 is guaranteed not to overflow, because |divisor| > 1. 0, -1,
// and 1 are already handled as special cases.
return ConstantRange(Lower, Upper + 1);
}
ConstantRange
ConstantRange::makeGuaranteedNoWrapRegion(Instruction::BinaryOps BinOp,
const ConstantRange &Other,
unsigned NoWrapKind) {
using OBO = OverflowingBinaryOperator;
assert(Instruction::isBinaryOp(BinOp) && "Binary operators only!");
assert((NoWrapKind == OBO::NoSignedWrap ||
NoWrapKind == OBO::NoUnsignedWrap) &&
"NoWrapKind invalid!");
bool Unsigned = NoWrapKind == OBO::NoUnsignedWrap;
unsigned BitWidth = Other.getBitWidth();
switch (BinOp) {
default:
llvm_unreachable("Unsupported binary op");
case Instruction::Add: {
if (Unsigned)
return getNonEmpty(APInt::getNullValue(BitWidth),
-Other.getUnsignedMax());
APInt SignedMinVal = APInt::getSignedMinValue(BitWidth);
APInt SMin = Other.getSignedMin(), SMax = Other.getSignedMax();
return getNonEmpty(
SMin.isNegative() ? SignedMinVal - SMin : SignedMinVal,
SMax.isStrictlyPositive() ? SignedMinVal - SMax : SignedMinVal);
}
case Instruction::Sub: {
if (Unsigned)
return getNonEmpty(Other.getUnsignedMax(), APInt::getMinValue(BitWidth));
APInt SignedMinVal = APInt::getSignedMinValue(BitWidth);
APInt SMin = Other.getSignedMin(), SMax = Other.getSignedMax();
return getNonEmpty(
SMax.isStrictlyPositive() ? SignedMinVal + SMax : SignedMinVal,
SMin.isNegative() ? SignedMinVal + SMin : SignedMinVal);
}
case Instruction::Mul:
if (Unsigned)
return makeExactMulNUWRegion(Other.getUnsignedMax());
return makeExactMulNSWRegion(Other.getSignedMin())
.intersectWith(makeExactMulNSWRegion(Other.getSignedMax()));
}
}
ConstantRange ConstantRange::makeExactNoWrapRegion(Instruction::BinaryOps BinOp,
const APInt &Other,
unsigned NoWrapKind) {
// makeGuaranteedNoWrapRegion() is exact for single-element ranges, as
// "for all" and "for any" coincide in this case.
return makeGuaranteedNoWrapRegion(BinOp, ConstantRange(Other), NoWrapKind);
}
bool ConstantRange::isFullSet() const {
return Lower == Upper && Lower.isMaxValue();
}
bool ConstantRange::isEmptySet() const {
return Lower == Upper && Lower.isMinValue();
}
bool ConstantRange::isWrappedSet() const {
return Lower.ugt(Upper) && !Upper.isNullValue();
}
bool ConstantRange::isUpperWrapped() const {
return Lower.ugt(Upper);
}
bool ConstantRange::isSignWrappedSet() const {
return Lower.sgt(Upper) && !Upper.isMinSignedValue();
}
bool ConstantRange::isUpperSignWrapped() const {
return Lower.sgt(Upper);
}
bool
ConstantRange::isSizeStrictlySmallerThan(const ConstantRange &Other) const {
assert(getBitWidth() == Other.getBitWidth());
if (isFullSet())
return false;
if (Other.isFullSet())
return true;
return (Upper - Lower).ult(Other.Upper - Other.Lower);
}
bool
ConstantRange::isSizeLargerThan(uint64_t MaxSize) const {
assert(MaxSize && "MaxSize can't be 0.");
// If this a full set, we need special handling to avoid needing an extra bit
// to represent the size.
if (isFullSet())
return APInt::getMaxValue(getBitWidth()).ugt(MaxSize - 1);
return (Upper - Lower).ugt(MaxSize);
}
bool ConstantRange::isAllNegative() const {
// Empty set is all negative, full set is not.
if (isEmptySet())
return true;
if (isFullSet())
return false;
return !isUpperSignWrapped() && !Upper.isStrictlyPositive();
}
bool ConstantRange::isAllNonNegative() const {
// Empty and full set are automatically treated correctly.
return !isSignWrappedSet() && Lower.isNonNegative();
}
APInt ConstantRange::getUnsignedMax() const {
if (isFullSet() || isUpperWrapped())
return APInt::getMaxValue(getBitWidth());
return getUpper() - 1;
}
APInt ConstantRange::getUnsignedMin() const {
if (isFullSet() || isWrappedSet())
return APInt::getMinValue(getBitWidth());
return getLower();
}
APInt ConstantRange::getSignedMax() const {
if (isFullSet() || isUpperSignWrapped())
return APInt::getSignedMaxValue(getBitWidth());
return getUpper() - 1;
}
APInt ConstantRange::getSignedMin() const {
if (isFullSet() || isSignWrappedSet())
return APInt::getSignedMinValue(getBitWidth());
return getLower();
}
bool ConstantRange::contains(const APInt &V) const {
if (Lower == Upper)
return isFullSet();
if (!isUpperWrapped())
return Lower.ule(V) && V.ult(Upper);
return Lower.ule(V) || V.ult(Upper);
}
bool ConstantRange::contains(const ConstantRange &Other) const {
if (isFullSet() || Other.isEmptySet()) return true;
if (isEmptySet() || Other.isFullSet()) return false;
if (!isUpperWrapped()) {
if (Other.isUpperWrapped())
return false;
return Lower.ule(Other.getLower()) && Other.getUpper().ule(Upper);
}
if (!Other.isUpperWrapped())
return Other.getUpper().ule(Upper) ||
Lower.ule(Other.getLower());
return Other.getUpper().ule(Upper) && Lower.ule(Other.getLower());
}
ConstantRange ConstantRange::subtract(const APInt &Val) const {
assert(Val.getBitWidth() == getBitWidth() && "Wrong bit width");
// If the set is empty or full, don't modify the endpoints.
if (Lower == Upper)
return *this;
return ConstantRange(Lower - Val, Upper - Val);
}
ConstantRange ConstantRange::difference(const ConstantRange &CR) const {
return intersectWith(CR.inverse());
}
static ConstantRange getPreferredRange(
const ConstantRange &CR1, const ConstantRange &CR2,
ConstantRange::PreferredRangeType Type) {
if (Type == ConstantRange::Unsigned) {
if (!CR1.isWrappedSet() && CR2.isWrappedSet())
return CR1;
if (CR1.isWrappedSet() && !CR2.isWrappedSet())
return CR2;
} else if (Type == ConstantRange::Signed) {
if (!CR1.isSignWrappedSet() && CR2.isSignWrappedSet())
return CR1;
if (CR1.isSignWrappedSet() && !CR2.isSignWrappedSet())
return CR2;
}
if (CR1.isSizeStrictlySmallerThan(CR2))
return CR1;
return CR2;
}
ConstantRange ConstantRange::intersectWith(const ConstantRange &CR,
PreferredRangeType Type) const {
assert(getBitWidth() == CR.getBitWidth() &&
"ConstantRange types don't agree!");
// Handle common cases.
if ( isEmptySet() || CR.isFullSet()) return *this;
if (CR.isEmptySet() || isFullSet()) return CR;
if (!isUpperWrapped() && CR.isUpperWrapped())
return CR.intersectWith(*this, Type);
if (!isUpperWrapped() && !CR.isUpperWrapped()) {
if (Lower.ult(CR.Lower)) {
// L---U : this
// L---U : CR
if (Upper.ule(CR.Lower))
return getEmpty();
// L---U : this
// L---U : CR
if (Upper.ult(CR.Upper))
return ConstantRange(CR.Lower, Upper);
// L-------U : this
// L---U : CR
return CR;
}
// L---U : this
// L-------U : CR
if (Upper.ult(CR.Upper))
return *this;
// L-----U : this
// L-----U : CR
if (Lower.ult(CR.Upper))
return ConstantRange(Lower, CR.Upper);
// L---U : this
// L---U : CR
return getEmpty();
}
if (isUpperWrapped() && !CR.isUpperWrapped()) {
if (CR.Lower.ult(Upper)) {
// ------U L--- : this
// L--U : CR
if (CR.Upper.ult(Upper))
return CR;
// ------U L--- : this
// L------U : CR
if (CR.Upper.ule(Lower))
return ConstantRange(CR.Lower, Upper);
// ------U L--- : this
// L----------U : CR
return getPreferredRange(*this, CR, Type);
}
if (CR.Lower.ult(Lower)) {
// --U L---- : this
// L--U : CR
if (CR.Upper.ule(Lower))
return getEmpty();
// --U L---- : this
// L------U : CR
return ConstantRange(Lower, CR.Upper);
}
// --U L------ : this
// L--U : CR
return CR;
}
if (CR.Upper.ult(Upper)) {
// ------U L-- : this
// --U L------ : CR
if (CR.Lower.ult(Upper))
return getPreferredRange(*this, CR, Type);
// ----U L-- : this
// --U L---- : CR
if (CR.Lower.ult(Lower))
return ConstantRange(Lower, CR.Upper);
// ----U L---- : this
// --U L-- : CR
return CR;
}
if (CR.Upper.ule(Lower)) {
// --U L-- : this
// ----U L---- : CR
if (CR.Lower.ult(Lower))
return *this;
// --U L---- : this
// ----U L-- : CR
return ConstantRange(CR.Lower, Upper);
}
// --U L------ : this
// ------U L-- : CR
return getPreferredRange(*this, CR, Type);
}
ConstantRange ConstantRange::unionWith(const ConstantRange &CR,
PreferredRangeType Type) const {
assert(getBitWidth() == CR.getBitWidth() &&
"ConstantRange types don't agree!");
if ( isFullSet() || CR.isEmptySet()) return *this;
if (CR.isFullSet() || isEmptySet()) return CR;
if (!isUpperWrapped() && CR.isUpperWrapped())
return CR.unionWith(*this, Type);
if (!isUpperWrapped() && !CR.isUpperWrapped()) {
// L---U and L---U : this
// L---U L---U : CR
// result in one of
// L---------U
// -----U L-----
if (CR.Upper.ult(Lower) || Upper.ult(CR.Lower))
return getPreferredRange(
ConstantRange(Lower, CR.Upper), ConstantRange(CR.Lower, Upper), Type);
APInt L = CR.Lower.ult(Lower) ? CR.Lower : Lower;
APInt U = (CR.Upper - 1).ugt(Upper - 1) ? CR.Upper : Upper;
if (L.isNullValue() && U.isNullValue())
return getFull();
return ConstantRange(std::move(L), std::move(U));
}
if (!CR.isUpperWrapped()) {
// ------U L----- and ------U L----- : this
// L--U L--U : CR
if (CR.Upper.ule(Upper) || CR.Lower.uge(Lower))
return *this;
// ------U L----- : this
// L---------U : CR
if (CR.Lower.ule(Upper) && Lower.ule(CR.Upper))
return getFull();
// ----U L---- : this
// L---U : CR
// results in one of
// ----------U L----
// ----U L----------
if (Upper.ult(CR.Lower) && CR.Upper.ult(Lower))
return getPreferredRange(
ConstantRange(Lower, CR.Upper), ConstantRange(CR.Lower, Upper), Type);
// ----U L----- : this
// L----U : CR
if (Upper.ult(CR.Lower) && Lower.ule(CR.Upper))
return ConstantRange(CR.Lower, Upper);
// ------U L---- : this
// L-----U : CR
assert(CR.Lower.ule(Upper) && CR.Upper.ult(Lower) &&
"ConstantRange::unionWith missed a case with one range wrapped");
return ConstantRange(Lower, CR.Upper);
}
// ------U L---- and ------U L---- : this
// -U L----------- and ------------U L : CR
if (CR.Lower.ule(Upper) || Lower.ule(CR.Upper))
return getFull();
APInt L = CR.Lower.ult(Lower) ? CR.Lower : Lower;
APInt U = CR.Upper.ugt(Upper) ? CR.Upper : Upper;
return ConstantRange(std::move(L), std::move(U));
}
ConstantRange ConstantRange::castOp(Instruction::CastOps CastOp,
uint32_t ResultBitWidth) const {
switch (CastOp) {
default:
llvm_unreachable("unsupported cast type");
case Instruction::Trunc:
return truncate(ResultBitWidth);
case Instruction::SExt:
return signExtend(ResultBitWidth);
case Instruction::ZExt:
return zeroExtend(ResultBitWidth);
case Instruction::BitCast:
return *this;
case Instruction::FPToUI:
case Instruction::FPToSI:
if (getBitWidth() == ResultBitWidth)
return *this;
else
return getFull();
case Instruction::UIToFP: {
// TODO: use input range if available
auto BW = getBitWidth();
APInt Min = APInt::getMinValue(BW).zextOrSelf(ResultBitWidth);
APInt Max = APInt::getMaxValue(BW).zextOrSelf(ResultBitWidth);
return ConstantRange(std::move(Min), std::move(Max));
}
case Instruction::SIToFP: {
// TODO: use input range if available
auto BW = getBitWidth();
APInt SMin = APInt::getSignedMinValue(BW).sextOrSelf(ResultBitWidth);
APInt SMax = APInt::getSignedMaxValue(BW).sextOrSelf(ResultBitWidth);
return ConstantRange(std::move(SMin), std::move(SMax));
}
case Instruction::FPTrunc:
case Instruction::FPExt:
case Instruction::IntToPtr:
case Instruction::PtrToInt:
case Instruction::AddrSpaceCast:
// Conservatively return getFull set.
return getFull();
};
}
ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
if (isEmptySet()) return getEmpty(DstTySize);
unsigned SrcTySize = getBitWidth();
assert(SrcTySize < DstTySize && "Not a value extension");
if (isFullSet() || isUpperWrapped()) {
// Change into [0, 1 << src bit width)
APInt LowerExt(DstTySize, 0);
if (!Upper) // special case: [X, 0) -- not really wrapping around
LowerExt = Lower.zext(DstTySize);
return ConstantRange(std::move(LowerExt),
APInt::getOneBitSet(DstTySize, SrcTySize));
}
return ConstantRange(Lower.zext(DstTySize), Upper.zext(DstTySize));
}
ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
if (isEmptySet()) return getEmpty(DstTySize);
unsigned SrcTySize = getBitWidth();
assert(SrcTySize < DstTySize && "Not a value extension");
// special case: [X, INT_MIN) -- not really wrapping around
if (Upper.isMinSignedValue())
return ConstantRange(Lower.sext(DstTySize), Upper.zext(DstTySize));
if (isFullSet() || isSignWrappedSet()) {
return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1),
APInt::getLowBitsSet(DstTySize, SrcTySize-1) + 1);
}
return ConstantRange(Lower.sext(DstTySize), Upper.sext(DstTySize));
}
ConstantRange ConstantRange::truncate(uint32_t DstTySize) const {
assert(getBitWidth() > DstTySize && "Not a value truncation");
if (isEmptySet())
return getEmpty(DstTySize);
if (isFullSet())
return getFull(DstTySize);
APInt LowerDiv(Lower), UpperDiv(Upper);
ConstantRange Union(DstTySize, /*isFullSet=*/false);
// Analyze wrapped sets in their two parts: [0, Upper) \/ [Lower, MaxValue]
// We use the non-wrapped set code to analyze the [Lower, MaxValue) part, and
// then we do the union with [MaxValue, Upper)
if (isUpperWrapped()) {
// If Upper is greater than or equal to MaxValue(DstTy), it covers the whole
// truncated range.
if (Upper.getActiveBits() > DstTySize ||
Upper.countTrailingOnes() == DstTySize)
return getFull(DstTySize);
Union = ConstantRange(APInt::getMaxValue(DstTySize),Upper.trunc(DstTySize));
UpperDiv.setAllBits();
// Union covers the MaxValue case, so return if the remaining range is just
// MaxValue(DstTy).
if (LowerDiv == UpperDiv)
return Union;
}
// Chop off the most significant bits that are past the destination bitwidth.
if (LowerDiv.getActiveBits() > DstTySize) {
// Mask to just the signficant bits and subtract from LowerDiv/UpperDiv.
APInt Adjust = LowerDiv & APInt::getBitsSetFrom(getBitWidth(), DstTySize);
LowerDiv -= Adjust;
UpperDiv -= Adjust;
}
unsigned UpperDivWidth = UpperDiv.getActiveBits();
if (UpperDivWidth <= DstTySize)
return ConstantRange(LowerDiv.trunc(DstTySize),
UpperDiv.trunc(DstTySize)).unionWith(Union);
// The truncated value wraps around. Check if we can do better than fullset.
if (UpperDivWidth == DstTySize + 1) {
// Clear the MSB so that UpperDiv wraps around.
UpperDiv.clearBit(DstTySize);
if (UpperDiv.ult(LowerDiv))
return ConstantRange(LowerDiv.trunc(DstTySize),
UpperDiv.trunc(DstTySize)).unionWith(Union);
}
return getFull(DstTySize);
}
ConstantRange ConstantRange::zextOrTrunc(uint32_t DstTySize) const {
unsigned SrcTySize = getBitWidth();
if (SrcTySize > DstTySize)
return truncate(DstTySize);
if (SrcTySize < DstTySize)
return zeroExtend(DstTySize);
return *this;
}
ConstantRange ConstantRange::sextOrTrunc(uint32_t DstTySize) const {
unsigned SrcTySize = getBitWidth();
if (SrcTySize > DstTySize)
return truncate(DstTySize);
if (SrcTySize < DstTySize)
return signExtend(DstTySize);
return *this;
}
ConstantRange ConstantRange::binaryOp(Instruction::BinaryOps BinOp,
const ConstantRange &Other) const {
assert(Instruction::isBinaryOp(BinOp) && "Binary operators only!");
switch (BinOp) {
case Instruction::Add:
return add(Other);
case Instruction::Sub:
return sub(Other);
case Instruction::Mul:
return multiply(Other);
case Instruction::UDiv:
return udiv(Other);
case Instruction::SDiv:
return sdiv(Other);
case Instruction::URem:
return urem(Other);
case Instruction::SRem:
return srem(Other);
case Instruction::Shl:
return shl(Other);
case Instruction::LShr:
return lshr(Other);
case Instruction::AShr:
return ashr(Other);
case Instruction::And:
return binaryAnd(Other);
case Instruction::Or:
return binaryOr(Other);
// Note: floating point operations applied to abstract ranges are just
// ideal integer operations with a lossy representation
case Instruction::FAdd:
return add(Other);
case Instruction::FSub:
return sub(Other);
case Instruction::FMul:
return multiply(Other);
default:
// Conservatively return getFull set.
return getFull();
}
}
ConstantRange
ConstantRange::add(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
if (isFullSet() || Other.isFullSet())
return getFull();
APInt NewLower = getLower() + Other.getLower();
APInt NewUpper = getUpper() + Other.getUpper() - 1;
if (NewLower == NewUpper)
return getFull();
ConstantRange X = ConstantRange(std::move(NewLower), std::move(NewUpper));
if (X.isSizeStrictlySmallerThan(*this) ||
X.isSizeStrictlySmallerThan(Other))
// We've wrapped, therefore, full set.
return getFull();
return X;
}
ConstantRange ConstantRange::addWithNoSignedWrap(const APInt &Other) const {
// Calculate the subset of this range such that "X + Other" is
// guaranteed not to wrap (overflow) for all X in this subset.
auto NSWRange = ConstantRange::makeExactNoWrapRegion(
BinaryOperator::Add, Other, OverflowingBinaryOperator::NoSignedWrap);
auto NSWConstrainedRange = intersectWith(NSWRange);
return NSWConstrainedRange.add(ConstantRange(Other));
}
ConstantRange
ConstantRange::sub(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
if (isFullSet() || Other.isFullSet())
return getFull();
APInt NewLower = getLower() - Other.getUpper() + 1;
APInt NewUpper = getUpper() - Other.getLower();
if (NewLower == NewUpper)
return getFull();
ConstantRange X = ConstantRange(std::move(NewLower), std::move(NewUpper));
if (X.isSizeStrictlySmallerThan(*this) ||
X.isSizeStrictlySmallerThan(Other))
// We've wrapped, therefore, full set.
return getFull();
return X;
}
ConstantRange
ConstantRange::multiply(const ConstantRange &Other) const {
// TODO: If either operand is a single element and the multiply is known to
// be non-wrapping, round the result min and max value to the appropriate
// multiple of that element. If wrapping is possible, at least adjust the
// range according to the greatest power-of-two factor of the single element.
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
// Multiplication is signedness-independent. However different ranges can be
// obtained depending on how the input ranges are treated. These different
// ranges are all conservatively correct, but one might be better than the
// other. We calculate two ranges; one treating the inputs as unsigned
// and the other signed, then return the smallest of these ranges.
// Unsigned range first.
APInt this_min = getUnsignedMin().zext(getBitWidth() * 2);
APInt this_max = getUnsignedMax().zext(getBitWidth() * 2);
APInt Other_min = Other.getUnsignedMin().zext(getBitWidth() * 2);
APInt Other_max = Other.getUnsignedMax().zext(getBitWidth() * 2);
ConstantRange Result_zext = ConstantRange(this_min * Other_min,
this_max * Other_max + 1);
ConstantRange UR = Result_zext.truncate(getBitWidth());
// If the unsigned range doesn't wrap, and isn't negative then it's a range
// from one positive number to another which is as good as we can generate.
// In this case, skip the extra work of generating signed ranges which aren't
// going to be better than this range.
if (!UR.isUpperWrapped() &&
(UR.getUpper().isNonNegative() || UR.getUpper().isMinSignedValue()))
return UR;
// Now the signed range. Because we could be dealing with negative numbers
// here, the lower bound is the smallest of the cartesian product of the
// lower and upper ranges; for example:
// [-1,4) * [-2,3) = min(-1*-2, -1*2, 3*-2, 3*2) = -6.
// Similarly for the upper bound, swapping min for max.
this_min = getSignedMin().sext(getBitWidth() * 2);
this_max = getSignedMax().sext(getBitWidth() * 2);
Other_min = Other.getSignedMin().sext(getBitWidth() * 2);
Other_max = Other.getSignedMax().sext(getBitWidth() * 2);
auto L = {this_min * Other_min, this_min * Other_max,
this_max * Other_min, this_max * Other_max};
auto Compare = [](const APInt &A, const APInt &B) { return A.slt(B); };
ConstantRange Result_sext(std::min(L, Compare), std::max(L, Compare) + 1);
ConstantRange SR = Result_sext.truncate(getBitWidth());
return UR.isSizeStrictlySmallerThan(SR) ? UR : SR;
}
ConstantRange
ConstantRange::smax(const ConstantRange &Other) const {
// X smax Y is: range(smax(X_smin, Y_smin),
// smax(X_smax, Y_smax))
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
APInt NewL = APIntOps::smax(getSignedMin(), Other.getSignedMin());
APInt NewU = APIntOps::smax(getSignedMax(), Other.getSignedMax()) + 1;
return getNonEmpty(std::move(NewL), std::move(NewU));
}
ConstantRange
ConstantRange::umax(const ConstantRange &Other) const {
// X umax Y is: range(umax(X_umin, Y_umin),
// umax(X_umax, Y_umax))
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
APInt NewL = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
APInt NewU = APIntOps::umax(getUnsignedMax(), Other.getUnsignedMax()) + 1;
return getNonEmpty(std::move(NewL), std::move(NewU));
}
ConstantRange
ConstantRange::smin(const ConstantRange &Other) const {
// X smin Y is: range(smin(X_smin, Y_smin),
// smin(X_smax, Y_smax))
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
APInt NewL = APIntOps::smin(getSignedMin(), Other.getSignedMin());
APInt NewU = APIntOps::smin(getSignedMax(), Other.getSignedMax()) + 1;
return getNonEmpty(std::move(NewL), std::move(NewU));
}
ConstantRange
ConstantRange::umin(const ConstantRange &Other) const {
// X umin Y is: range(umin(X_umin, Y_umin),
// umin(X_umax, Y_umax))
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
APInt NewL = APIntOps::umin(getUnsignedMin(), Other.getUnsignedMin());
APInt NewU = APIntOps::umin(getUnsignedMax(), Other.getUnsignedMax()) + 1;
return getNonEmpty(std::move(NewL), std::move(NewU));
}
ConstantRange
ConstantRange::udiv(const ConstantRange &RHS) const {
if (isEmptySet() || RHS.isEmptySet() || RHS.getUnsignedMax().isNullValue())
return getEmpty();
APInt Lower = getUnsignedMin().udiv(RHS.getUnsignedMax());
APInt RHS_umin = RHS.getUnsignedMin();
if (RHS_umin.isNullValue()) {
// We want the lowest value in RHS excluding zero. Usually that would be 1
// except for a range in the form of [X, 1) in which case it would be X.
if (RHS.getUpper() == 1)
RHS_umin = RHS.getLower();
else
RHS_umin = 1;
}
APInt Upper = getUnsignedMax().udiv(RHS_umin) + 1;
return getNonEmpty(std::move(Lower), std::move(Upper));
}
ConstantRange ConstantRange::sdiv(const ConstantRange &RHS) const {
// We split up the LHS and RHS into positive and negative components
// and then also compute the positive and negative components of the result
// separately by combining division results with the appropriate signs.
APInt Zero = APInt::getNullValue(getBitWidth());
APInt SignedMin = APInt::getSignedMinValue(getBitWidth());
ConstantRange PosFilter(APInt(getBitWidth(), 1), SignedMin);
ConstantRange NegFilter(SignedMin, Zero);
ConstantRange PosL = intersectWith(PosFilter);
ConstantRange NegL = intersectWith(NegFilter);
ConstantRange PosR = RHS.intersectWith(PosFilter);
ConstantRange NegR = RHS.intersectWith(NegFilter);
ConstantRange PosRes = getEmpty();
if (!PosL.isEmptySet() && !PosR.isEmptySet())
// pos / pos = pos.
PosRes = ConstantRange(PosL.Lower.sdiv(PosR.Upper - 1),
(PosL.Upper - 1).sdiv(PosR.Lower) + 1);
if (!NegL.isEmptySet() && !NegR.isEmptySet()) {
// neg / neg = pos.
//
// We need to deal with one tricky case here: SignedMin / -1 is UB on the
// IR level, so we'll want to exclude this case when calculating bounds.
// (For APInts the operation is well-defined and yields SignedMin.) We
// handle this by dropping either SignedMin from the LHS or -1 from the RHS.
APInt Lo = (NegL.Upper - 1).sdiv(NegR.Lower);
if (NegL.Lower.isMinSignedValue() && NegR.Upper.isNullValue()) {
// Remove -1 from the LHS. Skip if it's the only element, as this would
// leave us with an empty set.
if (!NegR.Lower.isAllOnesValue()) {
APInt AdjNegRUpper;
if (RHS.Lower.isAllOnesValue())
// Negative part of [-1, X] without -1 is [SignedMin, X].
AdjNegRUpper = RHS.Upper;
else
// [X, -1] without -1 is [X, -2].
AdjNegRUpper = NegR.Upper - 1;
PosRes = PosRes.unionWith(
ConstantRange(Lo, NegL.Lower.sdiv(AdjNegRUpper - 1) + 1));
}
// Remove SignedMin from the RHS. Skip if it's the only element, as this
// would leave us with an empty set.
if (NegL.Upper != SignedMin + 1) {
APInt AdjNegLLower;
if (Upper == SignedMin + 1)
// Negative part of [X, SignedMin] without SignedMin is [X, -1].
AdjNegLLower = Lower;
else
// [SignedMin, X] without SignedMin is [SignedMin + 1, X].
AdjNegLLower = NegL.Lower + 1;
PosRes = PosRes.unionWith(
ConstantRange(std::move(Lo),
AdjNegLLower.sdiv(NegR.Upper - 1) + 1));
}
} else {
PosRes = PosRes.unionWith(
ConstantRange(std::move(Lo), NegL.Lower.sdiv(NegR.Upper - 1) + 1));
}
}
ConstantRange NegRes = getEmpty();
if (!PosL.isEmptySet() && !NegR.isEmptySet())
// pos / neg = neg.
NegRes = ConstantRange((PosL.Upper - 1).sdiv(NegR.Upper - 1),
PosL.Lower.sdiv(NegR.Lower) + 1);
if (!NegL.isEmptySet() && !PosR.isEmptySet())
// neg / pos = neg.
NegRes = NegRes.unionWith(
ConstantRange(NegL.Lower.sdiv(PosR.Lower),
(NegL.Upper - 1).sdiv(PosR.Upper - 1) + 1));
// Prefer a non-wrapping signed range here.
ConstantRange Res = NegRes.unionWith(PosRes, PreferredRangeType::Signed);
// Preserve the zero that we dropped when splitting the LHS by sign.
if (contains(Zero) && (!PosR.isEmptySet() || !NegR.isEmptySet()))
Res = Res.unionWith(ConstantRange(Zero));
return Res;
}
ConstantRange ConstantRange::urem(const ConstantRange &RHS) const {
if (isEmptySet() || RHS.isEmptySet() || RHS.getUnsignedMax().isNullValue())
return getEmpty();
// L % R for L < R is L.
if (getUnsignedMax().ult(RHS.getUnsignedMin()))
return *this;
// L % R is <= L and < R.
APInt Upper = APIntOps::umin(getUnsignedMax(), RHS.getUnsignedMax() - 1) + 1;
return getNonEmpty(APInt::getNullValue(getBitWidth()), std::move(Upper));
}
ConstantRange ConstantRange::srem(const ConstantRange &RHS) const {
if (isEmptySet() || RHS.isEmptySet())
return getEmpty();
ConstantRange AbsRHS = RHS.abs();
APInt MinAbsRHS = AbsRHS.getUnsignedMin();
APInt MaxAbsRHS = AbsRHS.getUnsignedMax();
// Modulus by zero is UB.
if (MaxAbsRHS.isNullValue())
return getEmpty();
if (MinAbsRHS.isNullValue())
++MinAbsRHS;
APInt MinLHS = getSignedMin(), MaxLHS = getSignedMax();
if (MinLHS.isNonNegative()) {
// L % R for L < R is L.
if (MaxLHS.ult(MinAbsRHS))
return *this;
// L % R is <= L and < R.
APInt Upper = APIntOps::umin(MaxLHS, MaxAbsRHS - 1) + 1;
return ConstantRange(APInt::getNullValue(getBitWidth()), std::move(Upper));
}
// Same basic logic as above, but the result is negative.
if (MaxLHS.isNegative()) {
if (MinLHS.ugt(-MinAbsRHS))
return *this;
APInt Lower = APIntOps::umax(MinLHS, -MaxAbsRHS + 1);
return ConstantRange(std::move(Lower), APInt(getBitWidth(), 1));
}
// LHS range crosses zero.
APInt Lower = APIntOps::umax(MinLHS, -MaxAbsRHS + 1);
APInt Upper = APIntOps::umin(MaxLHS, MaxAbsRHS - 1) + 1;
return ConstantRange(std::move(Lower), std::move(Upper));
}
ConstantRange
ConstantRange::binaryAnd(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
// TODO: replace this with something less conservative
APInt umin = APIntOps::umin(Other.getUnsignedMax(), getUnsignedMax());
return getNonEmpty(APInt::getNullValue(getBitWidth()), std::move(umin) + 1);
}
ConstantRange
ConstantRange::binaryOr(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
// TODO: replace this with something less conservative
APInt umax = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
return getNonEmpty(std::move(umax), APInt::getNullValue(getBitWidth()));
}
ConstantRange
ConstantRange::shl(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
APInt max = getUnsignedMax();
APInt Other_umax = Other.getUnsignedMax();
// If we are shifting by maximum amount of
// zero return return the original range.
if (Other_umax.isNullValue())
return *this;
// there's overflow!
if (Other_umax.ugt(max.countLeadingZeros()))
return getFull();
// FIXME: implement the other tricky cases
APInt min = getUnsignedMin();
min <<= Other.getUnsignedMin();
max <<= Other_umax;
return ConstantRange(std::move(min), std::move(max) + 1);
}
ConstantRange
ConstantRange::lshr(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
APInt max = getUnsignedMax().lshr(Other.getUnsignedMin()) + 1;
APInt min = getUnsignedMin().lshr(Other.getUnsignedMax());
return getNonEmpty(std::move(min), std::move(max));
}
ConstantRange
ConstantRange::ashr(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
// May straddle zero, so handle both positive and negative cases.
// 'PosMax' is the upper bound of the result of the ashr
// operation, when Upper of the LHS of ashr is a non-negative.
// number. Since ashr of a non-negative number will result in a
// smaller number, the Upper value of LHS is shifted right with
// the minimum value of 'Other' instead of the maximum value.
APInt PosMax = getSignedMax().ashr(Other.getUnsignedMin()) + 1;
// 'PosMin' is the lower bound of the result of the ashr
// operation, when Lower of the LHS is a non-negative number.
// Since ashr of a non-negative number will result in a smaller
// number, the Lower value of LHS is shifted right with the
// maximum value of 'Other'.
APInt PosMin = getSignedMin().ashr(Other.getUnsignedMax());
// 'NegMax' is the upper bound of the result of the ashr
// operation, when Upper of the LHS of ashr is a negative number.
// Since 'ashr' of a negative number will result in a bigger
// number, the Upper value of LHS is shifted right with the
// maximum value of 'Other'.
APInt NegMax = getSignedMax().ashr(Other.getUnsignedMax()) + 1;
// 'NegMin' is the lower bound of the result of the ashr
// operation, when Lower of the LHS of ashr is a negative number.
// Since 'ashr' of a negative number will result in a bigger
// number, the Lower value of LHS is shifted right with the
// minimum value of 'Other'.
APInt NegMin = getSignedMin().ashr(Other.getUnsignedMin());
APInt max, min;
if (getSignedMin().isNonNegative()) {
// Upper and Lower of LHS are non-negative.
min = PosMin;
max = PosMax;
} else if (getSignedMax().isNegative()) {
// Upper and Lower of LHS are negative.
min = NegMin;
max = NegMax;
} else {
// Upper is non-negative and Lower is negative.
min = NegMin;
max = PosMax;
}
return getNonEmpty(std::move(min), std::move(max));
}
ConstantRange ConstantRange::uadd_sat(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
APInt NewL = getUnsignedMin().uadd_sat(Other.getUnsignedMin());
APInt NewU = getUnsignedMax().uadd_sat(Other.getUnsignedMax()) + 1;
return getNonEmpty(std::move(NewL), std::move(NewU));
}
ConstantRange ConstantRange::sadd_sat(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
APInt NewL = getSignedMin().sadd_sat(Other.getSignedMin());
APInt NewU = getSignedMax().sadd_sat(Other.getSignedMax()) + 1;
return getNonEmpty(std::move(NewL), std::move(NewU));
}
ConstantRange ConstantRange::usub_sat(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
APInt NewL = getUnsignedMin().usub_sat(Other.getUnsignedMax());
APInt NewU = getUnsignedMax().usub_sat(Other.getUnsignedMin()) + 1;
return getNonEmpty(std::move(NewL), std::move(NewU));
}
ConstantRange ConstantRange::ssub_sat(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return getEmpty();
APInt NewL = getSignedMin().ssub_sat(Other.getSignedMax());
APInt NewU = getSignedMax().ssub_sat(Other.getSignedMin()) + 1;
return getNonEmpty(std::move(NewL), std::move(NewU));
}
ConstantRange ConstantRange::inverse() const {
if (isFullSet())
return getEmpty();
if (isEmptySet())
return getFull();
return ConstantRange(Upper, Lower);
}
ConstantRange ConstantRange::abs() const {
if (isEmptySet())
return getEmpty();
if (isSignWrappedSet()) {
APInt Lo;
// Check whether the range crosses zero.
if (Upper.isStrictlyPositive() || !Lower.isStrictlyPositive())
Lo = APInt::getNullValue(getBitWidth());
else
Lo = APIntOps::umin(Lower, -Upper + 1);
// SignedMin is included in the result range.
return ConstantRange(Lo, APInt::getSignedMinValue(getBitWidth()) + 1);
}
APInt SMin = getSignedMin(), SMax = getSignedMax();
// All non-negative.
if (SMin.isNonNegative())
return *this;
// All negative.
if (SMax.isNegative())
return ConstantRange(-SMax, -SMin + 1);
// Range crosses zero.
return ConstantRange(APInt::getNullValue(getBitWidth()),
APIntOps::umax(-SMin, SMax) + 1);
}
ConstantRange::OverflowResult ConstantRange::unsignedAddMayOverflow(
const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return OverflowResult::MayOverflow;
APInt Min = getUnsignedMin(), Max = getUnsignedMax();
APInt OtherMin = Other.getUnsignedMin(), OtherMax = Other.getUnsignedMax();
// a u+ b overflows high iff a u> ~b.
if (Min.ugt(~OtherMin))
return OverflowResult::AlwaysOverflowsHigh;
if (Max.ugt(~OtherMax))
return OverflowResult::MayOverflow;
return OverflowResult::NeverOverflows;
}
ConstantRange::OverflowResult ConstantRange::signedAddMayOverflow(
const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return OverflowResult::MayOverflow;
APInt Min = getSignedMin(), Max = getSignedMax();
APInt OtherMin = Other.getSignedMin(), OtherMax = Other.getSignedMax();
APInt SignedMin = APInt::getSignedMinValue(getBitWidth());
APInt SignedMax = APInt::getSignedMaxValue(getBitWidth());
// a s+ b overflows high iff a s>=0 && b s>= 0 && a s> smax - b.
// a s+ b overflows low iff a s< 0 && b s< 0 && a s< smin - b.
if (Min.isNonNegative() && OtherMin.isNonNegative() &&
Min.sgt(SignedMax - OtherMin))
return OverflowResult::AlwaysOverflowsHigh;
if (Max.isNegative() && OtherMax.isNegative() &&
Max.slt(SignedMin - OtherMax))
return OverflowResult::AlwaysOverflowsLow;
if (Max.isNonNegative() && OtherMax.isNonNegative() &&
Max.sgt(SignedMax - OtherMax))
return OverflowResult::MayOverflow;
if (Min.isNegative() && OtherMin.isNegative() &&
Min.slt(SignedMin - OtherMin))
return OverflowResult::MayOverflow;
return OverflowResult::NeverOverflows;
}
ConstantRange::OverflowResult ConstantRange::unsignedSubMayOverflow(
const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return OverflowResult::MayOverflow;
APInt Min = getUnsignedMin(), Max = getUnsignedMax();
APInt OtherMin = Other.getUnsignedMin(), OtherMax = Other.getUnsignedMax();
// a u- b overflows low iff a u< b.
if (Max.ult(OtherMin))
return OverflowResult::AlwaysOverflowsLow;
if (Min.ult(OtherMax))
return OverflowResult::MayOverflow;
return OverflowResult::NeverOverflows;
}
ConstantRange::OverflowResult ConstantRange::signedSubMayOverflow(
const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return OverflowResult::MayOverflow;
APInt Min = getSignedMin(), Max = getSignedMax();
APInt OtherMin = Other.getSignedMin(), OtherMax = Other.getSignedMax();
APInt SignedMin = APInt::getSignedMinValue(getBitWidth());
APInt SignedMax = APInt::getSignedMaxValue(getBitWidth());
// a s- b overflows high iff a s>=0 && b s< 0 && a s> smax + b.
// a s- b overflows low iff a s< 0 && b s>= 0 && a s< smin + b.
if (Min.isNonNegative() && OtherMax.isNegative() &&
Min.sgt(SignedMax + OtherMax))
return OverflowResult::AlwaysOverflowsHigh;
if (Max.isNegative() && OtherMin.isNonNegative() &&
Max.slt(SignedMin + OtherMin))
return OverflowResult::AlwaysOverflowsLow;
if (Max.isNonNegative() && OtherMin.isNegative() &&
Max.sgt(SignedMax + OtherMin))
return OverflowResult::MayOverflow;
if (Min.isNegative() && OtherMax.isNonNegative() &&
Min.slt(SignedMin + OtherMax))
return OverflowResult::MayOverflow;
return OverflowResult::NeverOverflows;
}
ConstantRange::OverflowResult ConstantRange::unsignedMulMayOverflow(
const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return OverflowResult::MayOverflow;
APInt Min = getUnsignedMin(), Max = getUnsignedMax();
APInt OtherMin = Other.getUnsignedMin(), OtherMax = Other.getUnsignedMax();
bool Overflow;
(void) Min.umul_ov(OtherMin, Overflow);
if (Overflow)
return OverflowResult::AlwaysOverflowsHigh;
(void) Max.umul_ov(OtherMax, Overflow);
if (Overflow)
return OverflowResult::MayOverflow;
return OverflowResult::NeverOverflows;
}
void ConstantRange::print(raw_ostream &OS) const {
if (isFullSet())
OS << "full-set";
else if (isEmptySet())
OS << "empty-set";
else
OS << "[" << Lower << "," << Upper << ")";
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void ConstantRange::dump() const {
print(dbgs());
}
#endif
ConstantRange llvm::getConstantRangeFromMetadata(const MDNode &Ranges) {
const unsigned NumRanges = Ranges.getNumOperands() / 2;
assert(NumRanges >= 1 && "Must have at least one range!");
assert(Ranges.getNumOperands() % 2 == 0 && "Must be a sequence of pairs");
auto *FirstLow = mdconst::extract<ConstantInt>(Ranges.getOperand(0));
auto *FirstHigh = mdconst::extract<ConstantInt>(Ranges.getOperand(1));
ConstantRange CR(FirstLow->getValue(), FirstHigh->getValue());
for (unsigned i = 1; i < NumRanges; ++i) {
auto *Low = mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 0));
auto *High = mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 1));
// Note: unionWith will potentially create a range that contains values not
// contained in any of the original N ranges.
CR = CR.unionWith(ConstantRange(Low->getValue(), High->getValue()));
}
return CR;
}
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