| Issue |
136746
|
| Summary |
fshr-related miscompile by AArch64 backend
|
| Labels |
backend:AArch64,
llvm:codegen,
miscompilation
|
| Assignees |
|
| Reporter |
regehr
|
here's a function:
```llvm
; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i64 @llvm.fshr.i64(i64, i64, i64) #0
define i1 @f(i64 %0) {
%2 = or i64 1, %0
%3 = call i64 @llvm.fshr.i64(i64 %2, i64 %0, i64 0)
%4 = icmp uge i64 0, %3
ret i1 %4
}
attributes #0 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
```
the AArch64 backend lowers it as follows:
```
_f:
mov w0, wzr
ret
```
but `f(0)` should evaluate to 1 (and it does when compiled using Apple's latest clang)
(test case generated by @dtcxzyw's mutator)
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