[Bug fortran/30367] gfortran compile times excessive with -Wall

[Bil dot Kleb at NASA dot gov]

------- Comment #3 from Bil dot Kleb at NASA dot gov  2007-01-13 12:35 -------
I've just tried to duplicate the compile time difference with -Wall and found
that the -Wall was a red herring -- it always takes 169 minutes to compile our
code with gfortran, -Wall or not.

This is about 8 times longer than any other compiler, even with the SGI
compiler running on hardware that is an order of magnitude slower than the
hardware gfortran is running on.

Our current compiler guantlet includes: Absoft-10.0.3, NAG-5.1.282, g95-0.91,
PGI-6.2.4, Sun-8.3.35_2, gfortran-20070103, ifort-9.1.040, SGI-7.41,
LaheyX-6.10a, and LaheyX-8.00a.  (Where -O0 is the only compiler option
specified for all compilers.)

Gfortran's compilation time is mainly due to a three routines that take on the
order of 1/2 hour each. These routines are long (~10KLOC) and compute large
Jacobian matrices formed from many temporary variables.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30367