This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug libstdc++/66414] New: Regression: string::find ten times slower than strstr
- From: "neleai at seznam dot cz" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 04 Jun 2015 07:59:40 +0000
- Subject: [Bug libstdc++/66414] New: Regression: string::find ten times slower than strstr
- Auto-submitted: auto-generated
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66414
Bug ID: 66414
Summary: Regression: string::find ten times slower than strstr
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: neleai at seznam dot cz
Target Milestone: ---
Hi, as I seen bug with string::== being slower than using strcmp I decided to
check other functions for regressions. Here string::find doesn't simply call
optimized strstr and as result its ten times slower in following benchmark on
my sandy bridge.
#include <cstring>
#include <cstdlib>
#include <string>
using namespace std;
int
main()
{
int i;
char s[10000];
for (i = 0; i < 10000; i++)
s[i] = ((unsigned) rand() % 128) + 1;
s[9999] = 0;
int sum = 0;
std::string foo = s;
std::string bar;
char *needle = strdup("needle");
for (i = 0; i < 100000; i++)
{
needle[0] = ((unsigned) rand() % 128) + 1;
#ifdef STRSTR
sum += (long) strstr(s, needle);
#else
sum += foo.find(needle);
#endif
}
return sum;
}