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

Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> On 2013-01-11 15:52:19 -0500, Tom Lane wrote:
>> 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.

> Well, why use it at all then and not just rely on
> __builtin_unreachable() in any recent gcc (and llvm fwiw) and abort()
> otherwise? Then the code is small for anything recent (gcc 4.4 afair)
> and always consistently buggy.

Uh ... because it's *not* unreachable if elevel < ERROR. Otherwise we'd
just mark errfinish as __attribute((noreturn)) and be done. Of course,
that's a gcc-ism too.

regards, tom lane