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[Bug middle-end/47298] -O3 destroys beautifully vectorized code obtained at -O2
- 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: Fri, 14 Jan 2011 20:52:58 +0000
- Subject: [Bug middle-end/47298] -O3 destroys beautifully vectorized code obtained at -O2
- Auto-submitted: auto-generated
- References: <bug-47298-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47298
--- Comment #2 from Joost VandeVondele <Joost.VandeVondele at pci dot uzh.ch> 2011-01-14 20:52:54 UTC ---
(In reply to comment #1)
> It's faster for me with -O3 (Athlon64, using -march=native).
well not on
model name : Intel(R) Xeon(R) CPU X5550 @ 2.67GHz
stepping : 5
I have 8Gflops with -O2 and somewhat more than 4 with -O3
BTW, the proper test program is
> cat test_compare.f90
REAL(KIND=8), DIMENSION(12,12) :: A,B,C
A=0 ; B=0 ; C=0
DO I=1,10000000
CALL HARD_NN_12_12_12(C,A,B)
ENDDO
END