https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97225
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2020-09-28
Component|c |tree-optimization
Keywords| |missed-optimization
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think we've seen a duplicate report for this.
Confirmed. late phiopt sees (we need hoisting to get rid of the loads
in the two if arms):
<bb 2> [local count: 1073741824]:
_1 = vec_6(D)->size;
pretmp_9 = vec_6(D)->data;
if (_1 == 0)
goto <bb 4>; [34.00%]
else
goto <bb 3>; [66.00%]
<bb 3> [local count: 708669601]:
_3 = _1 * 4;
_7 = pretmp_9 + _3;
<bb 4> [local count: 1073741824]:
# _4 = PHI <_7(3), pretmp_9(2)>
return _4;
where it misses the value-conversion, possibly either based on lack
of handling the mult+add or because of consideration of making the
not infrequent path more expensive. Later if-converting this anyway
on RTL shows a disconnect in cost then.
