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From: "howarth at nitro dot med.uc.edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/46837] New: induct compiled with -ffast-math -fschedule-insns -fsched-pressure -O3 ~30% slower
Date: Tue, 07 Dec 2010 15:10:00 -0000 [thread overview]
Message-ID: <bug-46837-4@http.gcc.gnu.org/bugzilla/> (raw)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46837
Summary: induct compiled with -ffast-math -fschedule-insns
-fsched-pressure -O3 ~30% slower
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: howarth@nitro.med.uc.edu
The Polyhedron 2005 benchmark induct is 28% slower when compiled with
-ffast-math -fschedule-insns -fsched-pressure -O3 compared to -ffast-math -O3
(15.86 sec vs 12.43 sec) on x86_64-apple-darwin10 using -mtune=core2. This same
performance regression doesn't occur at -ffast-math -fschedule-insns
-fsched-pressure -O2 vs -ffast-math -O2.
The same effect is seen with both -mtune=generic (24%) as -mtune=core2 (28%) as
well as at
-m32 (33% with -mtune=core2 and 5% with -mtune=generic).
gfortran -ffast-math -O3 induct.f90 -o induct
tuning -mtune=core2
mtune=generic
------------------------------------
---------------------------------------
stock -fschedule-insns -fsched-pressure
stock -fschedule-insns -fsched-pressure
-m64 12.43s 15.86s
12.44s 15.57s
-m32 13.91s 18.63s
13.93s 14.69s
Using built-in specs.
COLLECT_GCC=gfortran
COLLECT_LTO_WRAPPER=/sw/lib/gcc4.6/libexec/gcc/x86_64-apple-darwin10.5.0/4.6.0/lto-wrapper
Target: x86_64-apple-darwin10.5.0
Configured with: ../gcc-4.6-20101206/configure --prefix=/sw
--prefix=/sw/lib/gcc4.6 --mandir=/sw/share/man --infodir=/sw/lib/gcc4.6/info
--enable-languages=c,c++,fortran,objc,obj-c++,java --with-gmp=/sw
--with-libiconv-prefix=/sw --with-ppl=/sw --with-cloog=/sw --with-mpc=/sw
--with-system-zlib --x-includes=/usr/X11R6/include --x-libraries=/usr/X11R6/lib
--program-suffix=-fsf-4.6 --enable-checking=yes --enable-cloog-backend=isl
Thread model: posix
gcc version 4.6.0 20101207 (experimental) (GCC)
r167525 with
next reply other threads:[~2010-12-07 15:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-07 15:10 howarth at nitro dot med.uc.edu [this message]
2010-12-07 16:23 ` [Bug middle-end/46837] " howarth at nitro dot med.uc.edu
2010-12-07 16:48 ` howarth at nitro dot med.uc.edu
2010-12-07 19:08 ` dominiq at lps dot ens.fr
2010-12-08 0:36 ` steven at gcc dot gnu.org
2012-12-12 16:59 ` howarth at nitro dot med.uc.edu
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