static ConstantRange makeSatisfyingICmpRegion(CmpInst::Predicate Pred,
const ConstantRange &Other);
- /// Return the largest range containing all X such that "X BinOpC C" does not
- /// wrap (overflow).
+ /// Return the largest range containing all X such that "X BinOpC C" is
+ /// guaranteed not to wrap (overflow).
+ ///
+ /// NB! The returned set does *not* contain **all** possible values of X for
+ /// which "X BinOpC C" does not wrap -- some viable values of X may be
+ /// missing, so you cannot use this to contrain X's range. E.g. in the last
+ /// example, "(-2) + 1" is both nsw and nuw (so the "X" could be -2), but (-2)
+ /// is not in the set returned.
///
/// Example:
/// typedef OverflowingBinaryOperator OBO;
/// makeNoWrapRegion(Add, i8 1, OBO::NoSignedWrap) == [-128, 127)
/// makeNoWrapRegion(Add, i8 1, OBO::NoUnsignedWrap) == [0, -1)
/// makeNoWrapRegion(Add, i8 0, OBO::NoUnsignedWrap) == Full Set
- static ConstantRange makeNoWrapRegion(Instruction::BinaryOps BinOp,
- const APInt &C, unsigned NoWrapKind);
+ /// makeNoWrapRegion(Add, i8 1, OBO::NoUnsignedWrap | OBO::NoSignedWrap) ==
+ /// [0,INT_MAX)
+ static ConstantRange makeGuaranteedNoWrapRegion(Instruction::BinaryOps BinOp,
+ const APInt &C,
+ unsigned NoWrapKind);
/// Return the lower value for this range.
///
const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
- auto NSWRegion =
- ConstantRange::makeNoWrapRegion(Instruction::Add, C, OBO::NoSignedWrap);
+ auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
+ Instruction::Add, C, OBO::NoSignedWrap);
if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
}
if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
- auto NUWRegion =
- ConstantRange::makeNoWrapRegion(Instruction::Add, C,
- OBO::NoUnsignedWrap);
+ auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
+ Instruction::Add, C, OBO::NoUnsignedWrap);
if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
}
.inverse();
}
-ConstantRange ConstantRange::makeNoWrapRegion(Instruction::BinaryOps BinOp,
- const APInt &C,
- unsigned NoWrapKind) {
+ConstantRange
+ConstantRange::makeGuaranteedNoWrapRegion(Instruction::BinaryOps BinOp,
+ const APInt &C, unsigned NoWrapKind) {
typedef OverflowingBinaryOperator OBO;
// Computes the intersection of CR0 and CR1. It is different from
for (int Const : {0, -1, -2, 1, 2, IntMin4Bits, IntMax4Bits}) {
APInt C(4, Const, true /* = isSigned */);
- auto NUWRegion =
- ConstantRange::makeNoWrapRegion(Instruction::Add, C, OBO::NoUnsignedWrap);
+ auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
+ Instruction::Add, C, OBO::NoUnsignedWrap);
EXPECT_FALSE(NUWRegion.isEmptySet());
- auto NSWRegion =
- ConstantRange::makeNoWrapRegion(Instruction::Add, C, OBO::NoSignedWrap);
+ auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
+ Instruction::Add, C, OBO::NoSignedWrap);
EXPECT_FALSE(NSWRegion.isEmptySet());
- auto NoWrapRegion = ConstantRange::makeNoWrapRegion(
+ auto NoWrapRegion = ConstantRange::makeGuaranteedNoWrapRegion(
Instruction::Add, C, OBO::NoSignedWrap | OBO::NoUnsignedWrap);
EXPECT_FALSE(NoWrapRegion.isEmptySet());