[petsc-users] How to change optimization flags?

Satish Balay balay at mcs.anl.gov
Wed Mar 7 14:38:45 CST 2018

COPTFLAGS is meant for optimization flags but CFLAGS should also work.
However since each of them have their own defaults - you would use the
correct one to override the defaults.

If the option you specify is not picked up - mostlikely petsc
configure attempted to use it - and configure rejected it.

You'll have to send us configure.log to figureout why they were rejected.


On Wed, 7 Mar 2018, Lucas Clemente Vella wrote:

> Despite documentation and output from "./configure --help", PETSC
> disregards completely all of the below:
> --CFLAGS=<string>
> --CXXFLAGS=<string>
> --FFLAGS=<string>
> --COPTFLAGS=<string>
> --FOPTFLAGS=<string>
> --CXXOPTFLAGS=<string>
> And also the customary environment variables CFLAGS and CXXFLAGS.
> How can I set special optimization flags, like enabling of SIMD
> instructions?

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