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From: "Joost.VandeVondele at pci dot uzh.ch" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/38306] [4.4/4.5/4.6/4.7 Regression] 15% slowdown w.r.t. 4.3 of computational kernel on some architectures
Date: Fri, 09 Sep 2011 19:11:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38306

Joost VandeVondele <Joost.VandeVondele at pci dot uzh.ch> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2011-02-20 19:01:16         |2011-09-09 19:01:16

--- Comment #24 from Joost VandeVondele <Joost.VandeVondele at pci dot uzh.ch> 2011-09-09 19:06:50 UTC ---
checked again current trunk, the situation remains that -O2 is much faster than
-O3:

> gfortran -O2 -march=native -funroll-loops  -ffast-math  -ftree-vectorize pr38306.f90  ; ./a.out
Time for evaluation [s]:                        2.830

> gfortran -O3 -march=native -funroll-loops  -ffast-math  -ftree-vectorize pr38306.f90  ; ./a.out
Time for evaluation [s]:                        4.593

The issue is that at -O3 the subroutine PD2VAL is not vectorized, while it is
at -O2.