| Issue |
175729
|
| Summary |
indvars miscompile
|
| Labels |
|
| Assignees |
|
| Reporter |
mikaelholmen
|
llvm commit: 4ef3f8dbc1c
Reproduce with:
```opt -passes=indvars bbi-113977.ll -S -o -```
Result:
```
define i16 @main() {
entry:
br label %vector.body
vector.body: ; preds = %vector.body, %entry
br i1 false, label %if.then, label %vector.body
if.then: ; preds = %vector.body
ret i16 0
}
```
Notice the infinite ```vector.body``` loop.
If we remove the "nuw" from the add
```%vec.next = add nuw i32 %vec, 4```
we instead get the correct result
```
define i16 @main() {
entry:
br label %vector.body
vector.body: ; preds = %vector.body, %entry
br i1 true, label %if.then, label %vector.body
if.then: ; preds = %vector.body
ret i16 0
}
```
But the result of the add is only used in a phi, which in turn is only used in the add, so it shouldn't matter.
This seems to be very old.
https://godbolt.org/z/Tbqc6Mv8a
[bbi-113977.ll.gz](https://github.com/user-attachments/files/24585344/bbi-113977.ll.gz)
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