https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102402
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Component|target |tree-optimization
Last reconfirmed| |2021-09-18
Status|UNCONFIRMED |NEW
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed, note the best code is generated by:
void ClearModM1(struct MusicPlayerTrack *track, uint8_t modT)
{
int t =0;
if (track->modT == 0)
t = 3;
else
t = 12;
track->flags |= t;
}
This is then a gimple level issue where:
if (_1 == 0)
goto <bb 3>; [50.00%]
else
goto <bb 4>; [50.00%]
<bb 3> [local count: 536870913]:
_3 = pretmp_6 | 3;
goto <bb 5>; [100.00%]
<bb 4> [local count: 536870913]:
_5 = pretmp_6 | 12;
<bb 5> [local count: 1073741824]:
# cstore_12 = PHI <_3(3), _5(4)>
is not transformed into:
if (track->modT == 0)
t = 3;
else
t = 12;
cstore_12 = pretmp_6 | t;
There is also a sinking issue though I don't know if has a wider effect (and
does not matter in this case really).
Take:
void ClearModM1(struct MusicPlayerTrack *track, uint8_t modT)
{
int t =0;
int t2 = track->modT;
int t1 = track->flags;
if (t2 == 0)
t = 3;
else
t = 12;
track->flags = t1|t;
}
The load for track->flags is not sunk after the if.
