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[Bug target/50182] Performance degradation from gcc 4.1 (x86_64)
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 25 Aug 2011 08:55:42 +0000
- Subject: [Bug target/50182] Performance degradation from gcc 4.1 (x86_64)
- Auto-submitted: auto-generated
- References: <bug-50182-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50182
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jakub at gcc dot gnu.org
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-25 08:55:42 UTC ---
The bugreport is incomplete, I don't see anywhere where you'd state what g++
options were meassured, what CPU was it on, is it -m32 or -m64, etc.
For me, on i7-2600 CPU 4.6.0 (both Fedora 4.6.0-10 and 20110727 4.6 branch
snapshot) is actually much faster than current trunk with -O3 -m64:
4.6.* gives roughly
0 "int8_t constant add" 0.84 sec 1904.76 M 1.00
while trunk
0 "int8_t constant add" 1.26 sec 1269.84 M 1.00
4.4.* gives also
0 "int8_t constant add" 1.26 sec 1269.84 M 1.00
4.3.* gives
0 "int8_t constant add" 1.26 sec 1269.84 M 1.00
4.2.* gives
0 "int8_t constant add" 0.84 sec 1904.76 M 1.00
and 4.1.* doesn't compile, because the source has been preprocessed and STL is
dependent on the compiler version.