Re: Change GUC hashtable to use simplehash?

On Wed, Mar 20, 2024 at 11:01 PM Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
>
> > I found that adding __attribute__((no_sanitize_address)) to
> > fasthash_accum_cstring_aligned() passes CI. While this kind of
> > exception is warned against (for good reason), I think it's fine here
> > given that glibc and NetBSD, and probably others, do something
> > similar
> > for optimized strlen(). Before I write the proper macro for that, are
> > there any objections? Better ideas?
>
> It appears that the spelling no_sanitize_address is deprecated in
> clang[1] in favor of 'no_sanitize("address")'. It doesn't appear to be
> deprecated in gcc[2].

Thanks for the pointers! In v20-0001, I've drafted checking thes
spelling first, since pg_attribute_no_sanitize_alignment has a similar
version check. Then it checks for no_sanitize_address using
__has_attribute, which goes back to gcc 5. That's plenty for the
buildfarm and CI, and I'm not sure it's worth expending additional
effort to cover more cases. (A similar attribute exists for MSVC in
case it comes up.)

v21-0003 adds a new file hashfn_unstable.c for convenience functions
and converts all the duplicate frontend uses of hash_string_pointer.

This will be where a similar hash_string_with_len will live for
dynash/dshash, which I tested some time ago. I haven't decided whether
to merge that earlier work here or keep it in a separate patch, but
regardless of how 0003 ends up I'd like to push 0001/0002 shortly.