| From: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | John Naylor <john(dot)naylor(at)enterprisedb(dot)com>, John Naylor <jcnaylor(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: optimize lookups in snapshot [sub]xip arrays |
| Date: | 2022-08-03 20:25:40 |
| Message-ID: | 20220803202540.GA1088968@nathanxps13 |
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| Thread: | |
| Lists: | pgsql-hackers |
On Wed, Aug 03, 2022 at 11:06:58AM -0700, Andres Freund wrote:
> On 2022-08-02 16:43:57 -0700, Nathan Bossart wrote:
>> >> +#ifdef USE_SSE2
>> >> +pg_attribute_no_sanitize_alignment()
>> >> +#endif
>> >
>> > What's the deal with this annotation? Needs a comment.
>>
>> Will do. c.h suggests that this should only be used for x86-specific code.
>
> What I'm asking is why the annotation is needed at all?
Upon further inspection, I don't think this is needed. I originally
borrowed it from the SSE version of the CRC code, but while it is trivial
to produce alignment failures with the CRC code, I haven't been able to
generate any with my patches. Looking at the code, I'm not sure why I was
worried about this in the first place. Please pardon the brain fade.
Here is a new patch set without the annotation.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
| Attachment | Content-Type | Size |
|---|---|---|
| v6-0001-Support-SSE2-intrinsics-where-available.patch | text/x-diff | 2.1 KB |
| v6-0002-Introduce-optimized-routine-for-linear-searches-t.patch | text/x-diff | 3.1 KB |
| v6-0003-Optimize-linear-searches-in-XidInMVCCSnapshot.patch | text/x-diff | 2.8 KB |
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