[Bug fortran/44334] rnflow.f90 ~27% slower with -fwhole-program -flto after revision 159852

[burnus at gcc dot gnu dot org]

------- Comment #11 from burnus at gcc dot gnu dot org  2010-09-09 09:00 -------
[Move comment from IRC #gcc to bugzilla]

(In reply to comment #9)
> For what it is worth, on AMD Athlon 64 X2 4800+ / x86-64-linux, [...]
> That's a +16% increase in run-time with -fwhole-program.

(In reply to comment #10)
> So hot-bb-frequency-fraction solves the whole regression?

For me (cf. system above), --param hot-bb-frequency-fraction=2000 reduces the
slow down due to -fwhole-program from 16% to 3%. (The LTO version with and
without -fwhole-file is about 2% slower than the corresponding -fno-lto
version.)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44334