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[Bug c++/43884] New: Performance degradation of the simple example (fibonacci) 4.3.3->4.5.0
- From: "yuri at tsoft dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 25 Apr 2010 07:18:25 -0000
- Subject: [Bug c++/43884] New: Performance degradation of the simple example (fibonacci) 4.3.3->4.5.0
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
I ran this simple example with the argument 45 through various versions of gcc
(option -O3):
#include <stdlib.h>
#include <stdio.h>
int fib(int AnArg) {
if (AnArg <= 2) return (1);
return (fib(AnArg-1)+fib(AnArg-2));
}
int main(int argc, char* argv[]) {
int n = atoi(argv[1]);
printf("fib(%i)=%i\n", n, fib(n));
}
Here are the average runtimes I got:
version time
4.3.1 3.930s
4.3.2 3.500s
4.3.3 3.470s
4.4.1 3.930s
4.4.3 3.940s
4.5.0 3.860s
I ran ~10 samples so values are approximate, but it's quite obvious that 4.5.0
has very significant degradation compared to 4.3.3.
Is there a performance suite for gcc that is ran for each release, are results
available online?
This case is pretty simple, basic. I would expect gcc to produce quite optimal
code for it.
--
Summary: Performance degradation of the simple example
(fibonacci) 4.3.3->4.5.0
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: yuri at tsoft dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43884