[Bug target/118976] [12/13/14/15 regression] Correctness Issue: SVE vectorization results in data corruption when cpu has 128bit vectors but compiled with -mcpu=neoverse-v1 (which is only for 256bit vector cpus)

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118976

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |rsandifo at gcc dot gnu.org
             Target|                            |aarch64

--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
But with -mcpu=neoverse-v1 you are still specifying the number of SVE bits to
256, so don't do that if the machine you run on behaves differently.

IMO this bug should be closed as INVALID (on x86 with AVX10 we might now run
into similar issues with 256bit vs 512bit implementations and models not only
being taken as a set of features).

So case in point this makes -mcpu a lot more fragile to users.

As I read it -msve-vector-bits=scalable is supposed to wipe any knowledge of
SVE vector bits?  If that doesn't work then it should be fixed.