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[Bug lto/45810] 40% slowdown when using LTO for a single-file program
- From: "Joost.VandeVondele at pci dot uzh.ch" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 28 Sep 2010 13:58:19 +0000
- Subject: [Bug lto/45810] 40% slowdown when using LTO for a single-file program
- Auto-submitted: auto-generated
- References: <bug-45810-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45810
--- Comment #5 from Joost VandeVondele <Joost.VandeVondele at pci dot uzh.ch> 2010-09-28 13:58:18 UTC ---
(In reply to comment #4)
> Sure. As with all performance related bugs this needs analysis and is
> unlikely an "LTO" problem - LTO does not (not-)optimize, optimization
> passes do.
I'm wondering if there is any description on how to do this. For example, how
do I get the assembly of a function and the -fdump-tree-all files from a gold
based linking that goes as:
rm -f test.s test2.s test.o test2.o ;
gfortran -c -flto test.f90 ;
gfortran -c -flto test2.f90 ;
gfortran -O3 -march=native -fuse-linker-plugin -fwhopr=2 test.o test2.o
just using -S or -fdump-tree-all doesn't work.
Is 'objdump -d' the only tool ?