Horton

Re: Keep elog(ERROR) and ereport(ERROR) calls in the cold path

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: David Rowley <dgrowleyml@gmail.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Andres Freund <andres@anarazel.de>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2020-11-24T21:11:59Z
Lists: pgsql-hackers 
Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> On 2020-Nov-24, Tom Lane wrote:
>> I'd make any such fix as narrow as possible (ie MINGW64 only, based on
>> present evidence).  It'd be nice to have a compiler version upper bound
>> too, in the hopes that they'd fix it in future.  Maybe something like
>> "#if defined(__MINGW64__) && defined(__GNUC__) && __GNUC__ <= 8" ?

> Apparently the bug was fixed days after it was reported,
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86048
> but they haven't made a release containing the fix yet.

Ah, great sleuthing!  So that says it occurs in 8.1 only, meaning
the version test could be like

#if defined(__MINGW64__) && __GNUC__ == 8 && __GNUC_MINOR__ == 1
// lobotomized code here
#else ...

It's not entirely clear from that bug report whether it can manifest on
gcc 8.1 on other platforms; maybe we should test for x86 in general
not __MINGW64__.

			regards, tom lane

Commits

  1. Stop gap fix for __attribute__((cold)) compiler bug in MinGW 8.1

  2. Tidy up definitions of pg_attribute_hot and pg_attribute_cold

  3. Fix unportable usage of __has_attribute

  4. Improve compiler code layout in elog/ereport ERROR calls

  5. Define pg_attribute_cold and pg_attribute_hot macros