If mpicc is providing a -On flag and the PETSc ./configure user provides a -Om flag should we generate a very useful error message telling them of the conflict?
Even generate an error? Barry On Jan 18, 2014, at 11:09 AM, Barry Smith <[email protected]> wrote: > > On Jan 18, 2014, at 10:43 AM, Jed Brown <[email protected]> wrote: > >> Barry Smith <[email protected]> writes: >>> Do people really set some of the above and not set the -O%d one at the >>> same time? >> >> I don't know. Sometimes the MPI wrapper adds the -O flag itself. The >> user might know that and thus not bother adding it themselves. I think >> it would be surprising for some special flags to cause such changes in >> behavior. I don't have a strong opinion on this point, but I think we >> should do something better than we have now. > > Summary > > The reason for the current model is that in the original plan > —with-debugging=0 would providing good compiler optimization flags (for each > system) without the user having to set them; if the user set them via > COPTFLAGS then we did set them ourselves. > > Observations > > 1) The “standard” for passing optimization flags to ./configure is > CFLAGS=“-O3 crap” we don’t support this and this confuses users > > 2) If we followed the standard and the user only set non-optimization > flags with CFLAGS we would not turn on optimization when user might expect it > (does this ever happen?) > > 3) We provide a different, “better" way of providing optimization flags > and other CFLAGS, but know one knows about it. > > 4) Our —with-debugging=0 optimization flags are pretty bad, we should > improve them > > So choices are > > A) follow standard > > B) Continue our way > > C) Hybrid that does not use our own flags if user provides optimization > flag. > > Request-assigned: Satish, if CLAGS contains a -O CXXFLAGS contains a -O > FFLAGS contains a -O then turn off PETSc generation of optimization flags for > that compiler > > Request-assigned: Satish, if mpicc, mpicxx, mpifc provide -O flags then turn > off PETSc generation of optimization flags > > Won’t completely satisfy anyone but me. > > Barry > > > >
