[petsc-users] petsc gcc intel and compilerflags

[Barry Smith]

  Manfred,

    ./configure is not smart enough to know what optimization flags are best for all compilers/systems. Thus we have relatively straightforward defaults. As Jed notes, if you know what flags are most appropriate for your build you must pass them in to ./configure

   Barry

On May 8, 2012, at 7:59 AM, Jed Brown wrote:

> On Tue, May 8, 2012 at 1:32 AM, Manfred Gratt <manfred.gratt at uibk.ac.at> wrote:
> when I compile petsc with --with-debugging=0 with gcc and icc in configure there are different optimization flags set depending on compiler. So is with gcc -O set wich means -O1 optimization. While with icc -O3 optimisation is set. Is there a reason only icc gets the high performance flag while gcc not? Are there any problems when some optimizations are activated on gcc?
> 
> I don't know why only -O1 is used with gcc, but you can pass COPTFLAGS='-O3 -march=native' or whatever you like to configure to make it use those instead.