Re: [PATCH] unified frontend support for pg_malloc et al and palloc/pfree mulation (was xlogreader-v4)

Andres Freund <andres@2ndquadrant.com> writes:
> On 2013-01-11 15:05:54 -0500, Tom Lane wrote:
>> And another thing: what if the elevel argument isn't safe for multiple
>> evaluation?  No such hazard ever existed before these patches, so I'm
>> not very comfortable with adding one.  (Even if all our own code is
>> safe, there's third-party code to worry about.)

> Hm. I am not really too scared about those dangers I have to admit.

I agree the scenario doesn't seem all that probable, but what scares me
here is that if we use "__builtin_constant_p(elevel) && (elevel) >= ERROR"
in some builds, and just "(elevel) >= ERROR" in others, then if there is
any code with a multiple-evaluation hazard, it is only buggy in the
latter builds.  That's sufficiently nasty that I'm willing to give up
an optimization that we never had before 9.3 anyway.

> I dislike the latter somewhat as it would mean not to give that
> information at all to msvc and others which seems a bit sad. But I don't
> feel particularly strongly.

It's not like our code isn't rather gcc-biased anyway.  I'd keep the
optimization for other compilers if possible, but not at the cost of
introducing bugs that occur only on those compilers.
        regards, tom lane