Re: AIX support - alignment issues

Hi,

On 2022-07-05 08:13:21 +0200, Peter Eisentraut wrote:
> On 05.07.22 07:31, Andres Freund wrote:
> > On 2022-07-02 11:33:54 -0700, Andres Freund wrote:
> > > If we decide we want to continue supporting AIX we should bite the bullet and
> > > add a 64bit-int TYPALIGN_*. It might be worth to translate that to bytes when
> > > building tupledescs, so we don't need more branches (reducing them compared to
> > > today).
> >
> > I just thought an easier way - why don't we introduce a 'catalog_double'
> > that's defined to be pg_attribute_aligned(whatever-we-need) on AIX? Then we
> > can get rid of the manually enforced alignedness and we don't need to contort
> > catalog order.
>
> Isn't the problem that on AIX, double and int64 have different alignment
> requirements, and we just check the one for double and apply it to int64?
> That ought to be fixable by two separate alignment checks in configure and a
> new alignment letter for pg_type.

Except that that's quite a bit of work to get right, particularly without
regressing the performance on all platforms. The attalign switches during
tuple deforming are already quite hot.

Greetings,

Andres Freund