Re: gcc 3.4 and Octave/lapack problems

[John W. Eaton]

On 11-Nov-2004, Dmitri A. Sergatskov <address@hidden> wrote:

| John W. Eaton wrote:
| > On 11-Nov-2004, Dmitri A. Sergatskov <address@hidden> wrote:
| > 
| > | Also, if -ffloat-store indeed the must for lapack/octave, should we
| > | make it a default?
| > 
| > It seems like this might be a reasonable change to make.  We'll need a
| > configure check since -ffloat-store probably only makes sense for
| > gcc/g++/g77.
| 
| I guess one of the questions weather we shall pass it to g77 only
| (at the moment that looks sufficient), or to all three?
| I noticed that loop performance drops some 20% if I have
| it in CXXFLAGS. I do not see any difference if CFLAGS have
| it or not.
| 
| Any insights?

If we are going to use -ffloat-store for Fortran code because it
produces better results (or at least results that are more likely to
agree with what we would expect from 64-bit IEEE floating point
arithmetic) then it seems to me that we should use it for the C and
C++ code as well.  Or maybe you would prefer to have bad results
faster?  :-)

I've made changes to configure so that we check to see if the
compilers accept -ffloat-store, but only on x86 platforms when using
platforms when using the GNU compilers (individual checks are made for
each).

jwe