[petsc-users] Using -ipo, -fast or -O3 during compilation of PETSc

[Satish Balay]

On Fri, 2 Mar 2012, Jed Brown wrote:

> On Fri, Mar 2, 2012 at 07:55, TAY wee-beng <zonexo at gmail.com> wrote:
> 
> > May I know if it is advisable to use -ipo, -fast or -O3 during compilation
> > of PETSc for the non debug mode?
> >
> > Will it be faster or will there be unpredictable errors?
> >
> 
> The only thing we can say for sure is that it will take longer to compile.
> 
> (It may be faster or slower, probably not by much. There should not be
> errors.)

The best way to see if it helps is to do a separate build of PETSc
with these options - and compare -log_summary for runs with and
without this option..

Note: Some compilers misbehave with '-fast' type options.. [not
returing error codes - when there are compile errors]. When this
happens - configure won't work properly..


Satish