Re: Fortran flags

[John W. Eaton]

On 10-May-2011, Jordi Gutiérrez Hermoso wrote:

| On 10 May 2011 15:08, Dmitri A. Sergatskov <address@hidden> wrote:
| > 2011/5/10 Thomas Weber <address@hidden>:
| >> On Tue, May 10, 2011 at 11:20:45AM -0500, Jordi Gutiérrez Hermoso wrote:
| >>> On 10 May 2011 10:12, Daniel Kraft <address@hidden> wrote:
| >>>
| >>> > Usually, -O2 should be a good thing for gfortran.  And in general, 
please
| >>> > report any "problems" -O2 causes as gfortran bug.
| >>>
| >>> I was wondering why it's not enabled in the default Fortran flags.
| >>> Instead we merely use -O. I thought the option enabled other
| >>> optimisation flags that caused problems. Red Hat for example broke ABI
| >>> compatibility by compiling with -O2:
| >>>
| >>>      https://bugzilla.redhat.com/show_bug.cgi?id=478856
| >>
| >> Maybe I don't get it, but I don't see anything in that bug report that
| >> even says someting about optimization flags?
| >>
| >>        Thomas
| >>
| >
| > I suspect he meant this bug:
| >
| > https://bugzilla.redhat.com/show_bug.cgi?id=520518#c0
| >
| > (and few ones related)
| > which showed up in all other distributions as well...
| > (It was not really RedHat specific).
| 
| Yes, thank you, about compilation Fortran flags. I read the first
| report too quickly.

We no longer include LAPACK sources in Octave, so I don't see how
setting FFLAGS to -O2 when building Octave could result in
miscompiling DLAMCH now.

jwe