| From: | Greg Stark <gsstark(at)mit(dot)edu> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Stephen Frost <sfrost(at)snowman(dot)net>, Jeremy Kerr <jk(at)ozlabs(dot)org>, "<pgsql-hackers(at)postgresql(dot)org>" <pgsql-hackers(at)postgresql(dot)org>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>, Gurjeet Singh <singh(dot)gurjeet(at)gmail(dot)com> |
| Subject: | Re: [PATCH] backend: compare word-at-a-time in bcTruelen |
| Date: | 2009-06-16 12:38:17 |
| Message-ID: | 407d949e0906160538i69444dafh45d16fec9987423e@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Jun 16, 2009 at 1:03 PM, Robert Haas<robertmhaas(at)gmail(dot)com> wrote:
> I see that... but I don't think the test in the first loop is correct.
> It's based on the value of i % 4, but I'm not convinced that you know
> anything about the alignment at the point where i == 0.
That's correct. To check the alignment you would have to look at the
actual pointer. I would suggest using the existing macros to handle
alignment. Hm, though the only one I see offhand which is relevant is
the moderately silly PointerIsAligned(). Still it would make the code
clearer even if it's pretty simple.
Incidentally, the char foo[4] = {' ',' ',' ',' '} suggestion is, I
think, bogus. There would be no alignment guarantee on that array.
Personally I'm find with 0x20202020 with a comment explaining what it
is.
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