Re: MAXIMUM_ALIGNOF on Windows-32 - Mailing list pgsql-hackers

From Pavan Deolasee
Subject Re: MAXIMUM_ALIGNOF on Windows-32
Date
Msg-id 2e78013d0707201042w22150b65o9a6add4956c77956@mail.gmail.com
Whole thread Raw
In response to Re: MAXIMUM_ALIGNOF on Windows-32  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers


On 7/20/07, Tom Lane <tgl@sss.pgh.pa.us> wrote:
"Pavan Deolasee" <pavan.deolasee@gmail.com> writes:
> The MAXIMUM_ALIGNOF value is set to 8 bytes in a Windows- 32-bit
> environment. I have very little knowledge about Windows, but at
> the face of it, this looks strange. Any idea why is this required ?

It's not entirely unreasonable.  The same thing happens on HPPA,
which is nominally a 32-bit architecture but the hardware requires
8-byte alignment of doubles (and maybe int64 too, I forget).
On newer Intel hardware it'd make sense to pad to avoid misaligned
fetches.

Anyway, we detect this directly based on the C compiler's behavior,
and you can't argue with the compiler about it.  Whatever it's
doing is right by definition.



Ah, that makes sense. I was confusing myself with 64-bit architectures
and alignments.

Thanks,
Pavan


--
Pavan Deolasee
EnterpriseDB     http://www.enterprisedb.com

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