anchovy failing on 9.1 and earlier since using gcc 4.8

Hi,

Anchovy is failing on 9.1 and earlier for quite some time now:
http://pgbuildfarm.org/cgi-bin/show_history.pl?nm=anchovy&br=REL9_1_STABLE
The commit at that date looks rather unconspicuous. Looking at the
'config' section reveals the difference between the failing
http://pgbuildfarm.org/cgi-bin/show_log.pl?nm=anchovy&dt=2013-03-31%2023%3A23%3A01
and
http://pgbuildfarm.org/cgi-bin/show_log.pl?nm=anchovy&dt=2013-03-30%2000%3A23%3A01

2013-03-30: config:

configure:3244: checking for C compiler version
configure:3252: gcc --version >&5
gcc (GCC) 4.7.2

2013-03-31: config:

configure:3244: checking for C compiler version
configure:3252: gcc --version >&5
gcc (GCC) 4.8.0

(note that it's using 4.8.1 these days)

So, it started failing the day it switched to gcc 4.8.

Given that anchovy builds 9.2 and master happily and given that it is
the only gcc-4.8 animal in the buildfarm it seems quite possible that
there is some misoptimization issue in 9.1 and earlier with 4.8.

I seem to recall some discussions about whether to backpatch some
hardening against compiler optimizations, but I don't remember any
specifics.

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services