https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105991
Bug ID: 105991
Summary: rldicl+sldi+add generated instead of rldimi
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: mpolacek at gcc dot gnu.org
Target Milestone: ---
Starting with r12-2731-g96146e61cd7aee, this code (on ppc64le)
unsigned long long
foo (unsigned long long value)
{
value &= 0xffffffff;
value |= value << 32;
return value;
}
compiled with -O2 generates
rldicl 9,3,0,32
sldi 3,3,32
add 3,3,9
blr
while previously it was just
rldimi 3,3,32,0
blr
It doesn't look like a wrong code problem, but it seems more optimal to use
rldimi (rotate left, mask insert) rather than rotate left by 0 bits, AND with a
mask, shift left, and add.
