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[Bug fortran/41137] inefficient zeroing of an array
- From: "burnus at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 21 Jun 2010 17:00:12 -0000
- Subject: [Bug fortran/41137] inefficient zeroing of an array
- References: <bug-41137-6642@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #10 from burnus at gcc dot gnu dot org 2010-06-21 17:00 -------
(In reply to comment #9)
> (In reply to comment #7)
> > I cannot reproduce the factor of 10 results, however.
> Here this still is the case (so might depend on the precise architecture):
OK, I was using -fwhole-file out of habit - thus the difference is that small
(all optimization levels, including -O0). Otherwise, I also get the same
factor-of-10 difference. If one splits it in two files, one needs to use "-O3
-flto" to get a fast program.
For comparison, using two files, ifort also shows a factor of 2 to 5 difference
(and is at -O0 ten times slower than gfortran; at -O2 it is twice as fast as
gfortran).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41137