| Issue |
63896
|
| Summary |
Failure to optimize based on umax implication
|
| Labels |
llvm:optimizations,
missed-optimization
|
| Assignees |
|
| Reporter |
nikic
|
https://alive2.llvm.org/ce/z/o_8ch3
```llvm
define i1 @src(i8 %x, i8 %y) {
%max = call i8 @llvm.umax.i8(i8 %x, i8 1)
%cmp = icmp ugt i8 %y, %max
br i1 %cmp, label %if, label %end
if:
%cmp2 = icmp ugt i8 %y, %x
ret i1 %cmp2
end:
ret i1 false
}
define i1 @tgt(i8 %x, i8 %y) {
%max = call i8 @llvm.umax.i8(i8 %x, i8 1)
%cmp = icmp ugt i8 %y, %max
br i1 %cmp, label %if, label %end
if:
ret i1 true
end:
ret i1 false
}
declare i8 @llvm.umax.i8(i8, i8)
```
This might be either for ConstraintElimination or InstCombine.
For the case where `icmp ugt i8 %y, 1` is used, CVP/LVI could also handle this.
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