| Issue |
115458
|
| Summary |
[InstCombine] miscompilation
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
bongjunj
|
Alive2 report: https://alive2.llvm.org/ce/z/GmGpRE
```llvm
----------------------------------------
define i8 @sext_multi_uses.2(i8 %a, i1 %b, i8 %x) {
#0:
%#1 = sext i1 %b to i8
%#2 = mul nsw i8 %a, %#1
%#3 = select i1 %b, i8 %#2, i8 %a
%#4 = sub i8 %#1, %#3
%f = mul nuw i8 %x, %#1
%r = add i8 %f, %#4
ret i8 %r
}
=>
define i8 @sext_multi_uses.2(i8 %a, i1 %b, i8 %x) {
#0:
%#1 = sub nsw i8 0, %a
%#2 = xor i8 %x, 255
%#3 = add i8 %a, %#2
%r = select i1 %b, i8 %#3, i8 %#1
ret i8 %r
}
Transformation doesn't verify!
ERROR: Target is more poisonous than source
Example:
i8 %a = #x80 (128, -128)
i1 %b = #x0 (0)
i8 %x = #x00 (0)
Source:
i8 %#1 = #x00 (0)
i8 %#2 = #x00 (0)
i8 %#3 = #x80 (128, -128)
i8 %#4 = #x80 (128, -128)
i8 %f = #x00 (0)
i8 %r = #x80 (128, -128)
Target:
i8 %#1 = poison
i8 %#2 = #xff (255, -1)
i8 %#3 = #x7f (127)
i8 %r = poison
Source value: #x80 (128, -128)
Target value: poison
Summary:
0 correct transformations
1 incorrect transformations
0 failed-to-prove transformations
0 Alive2 errors
```
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