[Bug middle-end/41743] New: Missing loop optimisation
segher at kernel dot crashing dot org
gcc-bugzilla@gcc.gnu.org
Sun Oct 18 14:00:00 GMT 2009
Take the following example code:
void *memset(void *b, int c, unsigned long len)
{
unsigned long i;
for (i = 0; i < len; i++)
((unsigned char *)b)[i] = c;
return b;
}
-O2 generates:
memset:
cmpwi 0,5,0
beqlr 0
mtctr 5
rlwinm 4,4,0,0xff
li 9,0
.p2align 4,,15
.L3:
stbx 4,3,9
addi 9,9,1
bdnz .L3
blr
The use of GPR9 is unnecessary, the loop could increment
GPR3 instead.
--
Summary: Missing loop optimisation
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: segher at kernel dot crashing dot org
GCC target triplet: powerpc-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41743
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