On 14/12/11 13:59, Andrew Dunstan wrote:

Hmm. Yeah, if I remove -O0 and instead set CFLAGS to -ffloat-store the
error goes away.

So, would we want to use that just for this file, or for the whole build?

Well the latest documentation for gcc gives 2 options: -ffloat-store and -fexcess-precision=<style> which are documented at http://gcc.gnu.org/onlinedocs/gcc-4.6.2/gcc/Optimize-Options.html#Optimize-Options.

For PostGIS we only applied the flags for specific files, because of severe performance warnings in older versions of the gcc documentation such as this: http://www.delorie.com/gnu/docs/gcc/gcc_10.html. I have no idea whether these warnings still hold true or not for more modern compiler versions.

ISTM that the best solution would be to determine whether or not -fexcess-precision=standard does the right thing (and also determine the performance hit) or take a look at the "excess precision" notes in the older documentation to see if parts of the code can be rearranged to eliminate the effect.



Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
t: +44 870 608 0063

Sirius Labs: http://www.siriusit.co.uk/labs

Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:

Reply via email to