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[Bug target/43884] [4.4/4.5/4.6 Regression] Performance degradation for simple fibonacci numbers calculation
- From: "hubicka at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Sat, 22 Jan 2011 21:46:38 +0000
- Subject: [Bug target/43884] [4.4/4.5/4.6 Regression] Performance degradation for simple fibonacci numbers calculation
- Auto-submitted: auto-generated
- References: <bug-43884-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43884
--- Comment #20 from Jan Hubicka <hubicka at gcc dot gnu.org> 2011-01-22 21:45:23 UTC ---
Patch posted http://gcc.gnu.org/ml/gcc-patches/2011-01/msg01597.html
I tested that is seems to bring us back to the 4.3 speed
jh@gcc10:~/trunk/build/gcc$ time ./a.out 45
fib(45)=1134903170
real 0m7.978s
user 0m7.976s
sys 0m0.000s
jh@gcc10:~/trunk/build/gcc$ gcc-4.3
Display all 708 possibilities? (y or n)
jh@gcc10:~/trunk/build/gcc$ gcc-4.3 -O3 tt.c
jh@gcc10:~/trunk/build/gcc$ time ./a.out 45
fib(45)=1134903170
real 0m7.902s
user 0m7.888s
sys 0m0.000s
and before patch
jh@gcc10:~/trunk/build2/gcc$ time ./a.out 45
fib(45)=1134903170
real 0m8.222s
user 0m8.213s
sys 0m0.000s