| Issue |
178644
|
| Summary |
[AArch64] llvm.experimental.cttz.elts.i64.v4i1 appears to be lowered incorrectly with SVE
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
fhahn
|
The IR snippet in https://godbolt.org/z/j9h98rcKT produces incorrect results with `-mcpu=neoverse-v2`, but works correctly with plain NEON. It looks like the major difference is that `llvm.experimental.cttz.elts.i64.v4i1 ` is lowered to SVE instructions, so I suspect this lowering is does not match the definition of the intrinsic.
To reproduce end-to-end, check out [aac5f40ab2fe91418e8727d4276bdcb5b08e1a70 from
](https://github.com/llvm/llvm-test-suite/commit/aac5f40ab2fe91418e8727d4276bdcb5b08e1a70) and build with `-mcpu=neoverse-v2` + run `SingleSource/UnitTests/Vectorizer/early-exit`
This should print a mismatch:
```
Checking early_exit_find_step_1
Miscompare for interleave-forced: 4 != 8
```
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