| Issue |
91178
|
| Summary |
[InstCombine] Miscompilation
|
| Labels |
miscompilation,
llvm:instcombine
|
| Assignees |
dtcxzyw
|
| Reporter |
dtcxzyw
|
Reduced test case: https://alive2.llvm.org/ce/z/_JyUGw
```
define i8 @func78(i1 %0, i8 %1) {
%3 = zext i1 %0 to i8
%4 = shl i8 %3, %1
%5 = freeze i8 %4
%6 = select i1 %0, i8 0, i8 %5
%7 = call i8 @llvm.fshr.i8(i8 0, i8 %5, i8 %6)
ret i8 %7
}
```
```
----------------------------------------
define i8 @func78(i1 %#0, i8 %#1) {
#2:
%#3 = zext i1 %#0 to i8
%#4 = shl i8 %#3, %#1
%#5 = freeze i8 %#4
%#6 = select i1 %#0, i8 0, i8 %#5
%#7 = fshr i8 0, i8 %#5, i8 %#6
ret i8 %#7
}
=>
define i8 @func78(i1 %#0, i8 %#1) nofree noundef willreturn memory(none) {
#2:
%#3 = zext i1 %#0 to i8
%#4 = shl nuw i8 %#3, %#1
%#5 = freeze i8 %#4
ret i8 %#5
}
Transformation doesn't verify!
ERROR: Value mismatch
Example:
i1 %#0 = #x0 (0)
i8 %#1 = #x08 (8)
Source:
i8 %#3 = #x00 (0)
i8 %#4 = poison
i8 %#5 = #x00 (0)
i8 %#6 = #x00 (0)
i8 %#7 = #x00 (0)
Target:
i8 %#3 = #x00 (0)
i8 %#4 = poison
i8 %#5 = #x9d (157, -99)
Source value: #x00 (0)
Target value: #x9d (157, -99)
Summary:
0 correct transformations
1 incorrect transformations
0 failed-to-prove transformations
0 Alive2 errors
```
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