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.
ATB,
Mark.
--
Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
http://www.siriusit.co.uk
t: +44 870 608 0063
Sirius Labs: http://www.siriusit.co.uk/labs
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