[Bug fortran/47495] .mod files: File modification time - Makefile build issue

[Joost.VandeVondele at pci dot uzh.ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47495

--- Comment #9 from Joost VandeVondele <Joost.VandeVondele at pci dot uzh.ch> 2011-01-29 12:36:01 UTC ---
BTW, there is one thing I would still like to add, but I have not yet tried.

gfortran -fsyntax-only test.f90

will generate all .mod files 'defined' by test.f90

This seems like a great way to speedup parallel builds. Right now, make -j X
often serializes at '-O3 ....' because code generation is slow. Using a two
stage compile

test.mod: test.f90
      gfortran -fsyntax-only test.f90

test.o: test.f90 test.mod
      gfortran -c -O3 test.f90

could speed things up for large parallel projects since the next file can be
compiled (modded ?) as soon as the .mod of the previous one has been generated,
there is no need to wait for the .o.