Re: Detecting pointer misalignment (was Re: pgsql: Implementation of subscripting for jsonb)

On Mon, Feb 8, 2021 at 7:49 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I wrote:
> > After digging in gcc's release history, it seems they invented
> > "-fsanitize=alignment" in GCC 5, so we can make this work for gcc
> > by writing
> > #if __GNUC__ >= 5
> > (the likely() macro already uses a similar approach). Can't say
> > if that's close enough for clang too.
>
> Ugh, no it isn't: even pretty recent clang releases only define
> __GNUC__ as 4. It looks like we need a separate test on clang's
> version. I looked at their version history and sanitizers seem
> to have come in around clang 7, so I propose the attached (where
> I worked a bit harder on the comment, too).

Looks good to me. Thank you for revising!

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Regards,
Alexander Korotkov