Compiler Optimization Override

[Aron Ahmadia]

Dear Tim,

I was just in Ireland a few weeks ago, had a great time climbing
Carantouhil and the Pilgrim's Path :D

Have you tried declaring a new $PETSC_ARCH and then overriding the
optimization flags in ./conf/configure?  PETSc likes to use the
$PETSC_ARCH flag to maintain all local builds under the same directory
structure instead of the -prefix flags common to autoconf-style
builds.

Ideally you'd do something like this...

declare -x PETSC_ARCH=petsc_linux_o3
cd $PETSC_DIR
./config/configure.py --COPTFLAGS=-O3
make

If you want to build a debugging version as well, then type:
declare -x PETSC_ARCH=petsc_debug
./config/configure.py --with-debugging=1

you'll then be able to use PETSc makefiles to build your code as long
as you declare your PETSC_ARCH and PETSC_DIR variables ahead of time.

Let me know if this works!
~Aron

On 6/27/07, Tim Stitt <timothy.stitt at ichec.ie> wrote:
> Hi PETSc Users/Developers,
>
> Could someone explain how I can override the default optimization level that
> comes with my PETSc build (currently -O). I want to set a more aggressive
> optimization level (e.g. -O3) for my compiler (PathScale).
>
> Ideally I would prefer a solution which doesn't involve rebuilding PETSc each
> time I want to switch the optimization level. I tried to add the switch to
> the petscrules file but it always defaulted to the first (lower?)
> optimization switch that appeared in the application compile command line
> which seems to be built into PETSc.
>
> Any help gratefully received.
>
> Regards,
>
> Tim.
>
> --
> Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie>
> HPC Application Consultant - ICHEC (www.ichec.ie)
>
> Dublin Institute for Advanced Studies
> 5 Merrion Square - Dublin 2 - Ireland
>
> +353-1-6621333 (tel) / +353-1-6621477 (fax) / +353-874195427 (mobile)
>
>