| Issue |
90020
|
| Summary |
[InstCombine] Failure to infer nuw for mul nsw of non-negative
|
| Labels |
llvm:instcombine,
missed-optimization
|
| Assignees |
nikic
|
| Reporter |
nikic
|
We currently fail to infer mul nuw if we have mul nsw and the operands are non-negative.
https://alive2.llvm.org/ce/z/2Dz9Uu
```llvm
define i8 @src(i8 %x, i8 %y) {
%x.nneg = icmp sge i8 %x, 0
call void @llvm.assume(i1 %x.nneg)
%y.nneg = icmp sge i8 %y, 0
call void @llvm.assume(i1 %y.nneg)
%mul = mul nsw i8 %x, %y
ret i8 %mul
}
define i8 @tgt(i8 %x, i8 %y) {
%mul = mul nuw i8 %x, %y
ret i8 %mul
}
```
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