| Issue |
113860
|
| Summary |
Wrong simplification of `or` and `icmp`s on a undefined value
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
bongjunj
|
Alive2 report: https://alive2.llvm.org/ce/z/gu_KaN
`(y >= (x | y)) | (x = 0) -> (x | y) = y`
```llvm
----------------------------------------
define i1 @ule_swap_or_min.2(i8 %x, i8 %y) {
#0:
%#1 = or i8 %x, %y
%cmp = icmp uge i8 %y, %#1
%cmpeq = icmp eq i8 %x, 0
%r = or i1 %cmp, %cmpeq
ret i1 %r
}
=>
define i1 @ule_swap_or_min.2(i8 %x, i8 %y) {
#0:
%#1 = or i8 %x, %y
%cmp = icmp eq i8 %#1, %y
ret i1 %cmp
}
Transformation doesn't verify!
ERROR: Target's return value is more undefined
Example:
i8 %x = #x00 (0)
i8 %y = undef
Source:
i8 %#1 = #x00 (0) [based on undef value]
i1 %cmp = #x1 (1)
i1 %cmpeq = #x1 (1)
i1 %r = #x1 (1)
Target:
i8 %#1 = #x00 (0)
i1 %cmp = #x0 (0)
Source value: #x1 (1)
Target value: #x0 (0)
Summary:
0 correct transformations
1 incorrect transformations
0 failed-to-prove transformations
0 Alive2 errors
```
![]()
_______________________________________________
llvm-bugs mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
