http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57511
Bug ID: 57511
Summary: [4.8/4.9 Regression] Missing SCEV final value
replacement
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: amonakov at gcc dot gnu.org
The following simple loop is no longer optimized out with 4.8 and 4.9:
int main(int argc, char* argv[])
{
int i, a = 0;
for (i=0; i < 10000; i++)
a += i + 0xff00ff;
return a;
}
$ gcc-4.7.2 -O2 -S main.c -o-
main:
.LFB0:
.cfi_startproc
movl $-334379544, %eax
ret
$ gcc-4.8.0 -O2 -S main.c -o-
main:
.LFB0:
.cfi_startproc
movl $16711935, %edx
xorl %eax, %eax
.p2align 4,,10
.p2align 3
.L3:
addl %edx, %eax
addl $1, %edx
cmpl $16721935, %edx
jne .L3
rep ret
