Re: Not-terribly-safe checks for CRC intrinsic support

John Naylor <johncnaylorls(at)gmail(dot)com> writes:
> On Sat, Mar 15, 2025 at 6:04 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> In short, I think we ought to apply and perhaps back-patch something
>> like the attached.

> Seems like reasonable defensive coding and consistency.

Thanks for looking at it.

> I'd be okay with keeping the original comment, though, since it seems
> to be explaining the choice well enough.

Okay.

>> BTW, it looks to me like PGAC_AVX512_POPCNT_INTRINSICS is at similar
>> hazard, but I'm not entirely sure how to fix that one.

> "buf" is the variable there that we're loading from, so that would be
> the one to make global.

Ah. I was confused by the "const" decoration, but we can remove that.

After thinking for a bit, I pushed this just to master rather than
back-patching. We can do a back-patch if anyone discovers that this
is a live issue on any current platform, but I rather suspect that
it isn't. Compiler not matched to platform is a situation that's
gone away for most people.

regards, tom lane