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[ConstantRange] Fix sdiv() with one bit values (PR56333) 

Signed one bit values can only be -1 or 0, not positive. The code
was interpreting the 1 as -1 and intersecting with a full range
rather than an empty one.

Fixes https://github.com/llvm/llvm-project/issues/56333.
This commit is contained in:
Nikita Popov 2022-07-01 15:43:27 +02:00
parent 5166345f50
commit ba1e04b966
2 changed files with 7 additions and 1 deletions
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5
llvm/lib/IR/ConstantRange.cpp
View File

@ -1238,7 +1238,10 @@ ConstantRange ConstantRange::sdiv(const ConstantRange &RHS) const {
// separately by combining division results with the appropriate signs.
APInt Zero = APInt::getZero(getBitWidth());
APInt SignedMin = APInt::getSignedMinValue(getBitWidth());
ConstantRange PosFilter(APInt(getBitWidth(), 1), SignedMin);
// There are no positive 1-bit values. The 1 would get interpreted as -1.
ConstantRange PosFilter =
getBitWidth() == 1 ? getEmpty()
: ConstantRange(APInt(getBitWidth(), 1), SignedMin);
ConstantRange NegFilter(SignedMin, Zero);
ConstantRange PosL = intersectWith(PosFilter);
ConstantRange NegL = intersectWith(NegFilter);

3
llvm/unittests/IR/ConstantRangeTest.cpp
View File

@ -1259,6 +1259,9 @@ TEST_F(ConstantRangeTest, UDiv) {
}
TEST_F(ConstantRangeTest, SDiv) {
ConstantRange OneBit = ConstantRange::getFull(1);
EXPECT_EQ(OneBit.sdiv(OneBit), ConstantRange(APInt(1, 0)));
unsigned Bits = 4;
EnumerateTwoConstantRanges(Bits, [&](const ConstantRange &CR1,
const ConstantRange &CR2) {