[PATCH 2/3] bpf: md: fix "*movsi" to generate wN regs [PR124688]

[Vineet Gupta]

On 4/3/26 9:09 AM, David Faust wrote:
>>> BUT, I am confused.  This test passes on my system compiled with
>>> gcc trunk.  After the call, we emit a movs32 when moving the return value
>>> to a different register, which is enough for the verifier to know the
>>> value is restricted to signed integer range.
>>>
>>> Are you seeing this with trunk or with the PROMOTE_MODE or some other
>>> change applied?
>> Yeah it's specifically with PROMOTE_MODE part of the ABI change, w/o
>> touching target hooks.
> I see.
>
> At this point it seems clear that there is no correctness issue with the
> moves currently generated by gcc trunk.
>
> Rather, the question is about the verifiability of the resulting code.
> But verifier issues raised here also do not reproduce with gcc trunk.
>
> Can you please send a reduced example showing precisely what code is
> being rejected by the verifier (despite being semantically correct)
> _as generated by gcc trunk_ ?
>
> If these issues only appear with a patched gcc, then this patch to
> address those issues should be part of a patchset including all other
> changes which would necessitate this fix.

Yeah that's what I concluded as well on this thread and IRC.

> You are introducing a lot of confusion by sending a patch against
> issues that do not seem to exist in trunk.

Yep.

-Vineet