[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

pb with -ffast-math

From: Alain Baeckeroot
Subject: pb with -ffast-math
Date: Tue, 14 Apr 2009 09:54:48 +0200
User-agent: KMail/1.9.9


i builded octave with additional optimisation flags
> FFLAGS = -O -mieee-fp -march=native 
> XTRA_CFLAGS =  -mieee-fp -march=native
> XTRA_CXXFLAGS =  -mieee-fp -march=native

Adding just -march=native is fine, and it seems that the build
is significantly faster (10-20%) than the one shipped with my distro
(debian lenny 32bit, on core2duo T5550)

All tests are OK (but 2 expected failures).

when i add the -ffast-math option, it builds, but segfault at runtime:

$ make 
Octave successfully built.  Now choose from the following:

   ./run-octave    - to run in place to test before installing
   make check      - to run the tests
   make install    - to install

make[1]: quittant le répertoire « /opt/octave-3.0.5 »

$ ./run-octave
 ** On entry to octave parameter number 13 had an illegal value
Erreur de segmentation

1/ Is it normal ?
2/ Are there some optimisation flags i should set to
improve speed. We have numerous independant short computations, and
need no precision (2 significant digit is good enought)
I thought to add -funsafe-math-optimizations -ffinite-math-only ,
but only after trying simpler stuff.

And this is really not important, i doubt we can get another 20%
speed improvement.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]