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[Bug target/19672] [3.4/4.0/4.1 Regression] Performance regression in simple loop code
- From: "dank at kegel dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 27 Jun 2005 06:59:22 -0000
- Subject: [Bug target/19672] [3.4/4.0/4.1 Regression] Performance regression in simple loop code
- References: <20050128162036.19672.stephan.bergmann@sun.com>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From dank at kegel dot com 2005-06-27 06:59 -------
I just reproduced this on two flavors of pentium 4 using -O3 -mtune=pentium.
The regression is worse, sometimes much worse, with -fPIC.
Times for gcc-2.95.3, gcc-3.4.3, gcc-4.0.0, gcc-4.1-20050603:
test run 1:
/proc/cpuinfo: cpu family 15, model 2, Intel Pentium 4 CPU 2.80GHz.
no -fPIC: 2.2, 2.7. 0.6. 0.6 seconds
with fPIC: 2.2, 2.9, 2.9, 2.9 seconds
test run 2:
/proc/cpuinfo: cpu family 15, model 4, Intel Pentium 4 CPU 3.20GHz
no -fPIC: 1.9, 3.2, 0.5, n/a seconds
with fPIC: 1.9, 3.6, 3.6, n/a seconds
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19672