| Issue |
132926
|
| Summary |
Non-deterministic results from MemorySSAUpdater due to iteration order
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
mikaelholmen
|
llvm commit: 6e66cfeeaec6
Build opt with and without LLVM_ENABLE_REVERSE_ITERATION and then do:
```
build-all/bin/opt "-passes=loop-mssa(licm<no-allowspeculation>,loop-rotate<header-duplication;no-prepare-for-lto>,licm<allowspeculation>)" bbi-104167.ll -o bbi-104167.norev.ll -S
build-all-reverse/bin/opt "-passes=loop-mssa(licm<no-allowspeculation>,loop-rotate<header-duplication;no-prepare-for-lto>,licm<allowspeculation>)" bbi-104167.ll -o bbi-104167.rev.ll -S
```
Then if we diff the two output files:
```
diff bbi-104167.norev.ll bbi-104167.rev.ll
```
we get
```
11d10
< %0 = load ptr, ptr @ao, align 1
15c14
< %1 = load volatile i32, ptr null, align 1
---
> %0 = load volatile i32, ptr null, align 1
42c41
< %2 = load volatile i16, ptr null, align 1
---
> %1 = load volatile i16, ptr null, align 1
77c76,77
< store double 0.000000e+00, ptr %0, align 1
---
> %2 = load ptr, ptr @ao, align 1
> store double 0.000000e+00, ptr %2, align 1
```
[bbi-104167.ll.gz](https://github.com/user-attachments/files/19447973/bbi-104167.ll.gz)
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