| Issue |
136650
|
| Summary |
[InstCombine] Poison safety violation in `foldLogicOfFCmps`
|
| Labels |
miscompilation,
llvm:instcombine
|
| Assignees |
dtcxzyw
|
| Reporter |
dtcxzyw
|
Reproducer: https://alive2.llvm.org/ce/z/Qcvvgi
```
----------------------------------------
define i1 @src(half %x, half %y) {
#0:
%copysign.x = copysign half %x, %y
%ord = fcmp ord half %x, 0x0000
%cmp = fcmp uge half %copysign.x, 0x7c00
%#1 = select i1 %ord, i1 %cmp, i1 0
ret i1 %#1
}
=>
define i1 @src(half %x, half %y) nofree willreturn memory(none) {
#0:
%copysign.x = copysign half %x, %y
%#1 = fcmp oeq half %copysign.x, 0x7c00
ret i1 %#1
}
Transformation doesn't verify!
ERROR: Target is more poisonous than source
Example:
half %x = #x7c02 (SNaN)
half %y = poison
Source:
half %copysign.x = poison
i1 %ord = #x0 (0)
i1 %cmp = poison
i1 %#1 = #x0 (0)
Target:
half %copysign.x = poison
i1 %#1 = poison
Source value: #x0 (0)
Target value: poison
Summary:
0 correct transformations
1 incorrect transformations
0 failed-to-prove transformations
0 Alive2 errors
```
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