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[Bug lto/45810] 40% slowdown when using LTO for a single-file program


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45810

Jack Howarth <howarth at nitro dot med.uc.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |howarth at nitro dot
                   |                            |med.uc.edu

--- Comment #23 from Jack Howarth <howarth at nitro dot med.uc.edu> 2011-01-24 17:58:00 UTC ---
(In reply to comment #22)

> That FRE pass should be after pass_sra_early (certainly after
> pass_build_ealias).

Index: gcc/passes.c
===================================================================
--- gcc/passes.c    (revision 169145)
+++ gcc/passes.c    (working copy)
@@ -767,6 +767,7 @@ init_optimization_passes (void)
          locals into SSA form if possible.  */
       NEXT_PASS (pass_build_ealias);
       NEXT_PASS (pass_sra_early);
+          NEXT_PASS (pass_fre);
       NEXT_PASS (pass_copy_prop);
       NEXT_PASS (pass_merge_phi);
       NEXT_PASS (pass_cd_dce);

gives Elapsed CPU time  =     8.43600E+00 for

gfortran -O3 -ffast-math -funroll-loops -flto -fwhole-program fatigue.f90 -o
fatigue

and Elapsed CPU time  =     4.16600E+00 for

gfortran -O3 -ffast-math -funroll-loops -finline-limit=250 --param
large-function-growth=250 -flto -fwhole-program fatigue.f90 -o fatigue


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