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[Bug rtl-optimization/37571] New: Performance regression with -mtune=core2
- From: "Joey dot ye at intel dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 18 Sep 2008 15:59:01 -0000
- Subject: [Bug rtl-optimization/37571] New: Performance regression with -mtune=core2
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
On Core2 ix86 machine following case (reduced from cpu2000.mcf) runs 50% slower
if compiled with trunk -mtune=core2 -O2
unsigned int g_i,g_j;
unsigned int g_a=1,g_b;
void __attribute__((noinline)) foo()
{
do {
if (g_a & g_i)
{g_i++;}
else
{g_j++;}
} while (g_b--);
}
int main()
{
int i;
for (i=0; i<4; i++)
{
g_b=0x7fffffff;
foo();
}
return 0;
}
--
Summary: Performance regression with -mtune=core2
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: Joey dot ye at intel dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37571