https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125579
Drea Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2026-06-03
Ever confirmed|0 |1
--- Comment #2 from Drea Pinski <pinskia at gcc dot gnu.org> ---
Confirmed. I think it is trying to delete a stmt it already deleted earlier.
Before backprop we have:
```
<bb 2> [local count: 118111600]:
a.0_1 = a;
if (a.0_1 != 0)
goto <bb 3>; [50.00%]
else
goto <bb 5>; [50.00%]
<bb 3> [local count: 59055800]:
_2 = 0 / 0;
e_3 = -_2;
goto <bb 5>; [100.00%]
<bb 4> [local count: 955630224]:
// predicted unlikely by continue predictor.
goto <bb 6>; [100.00%]
<bb 5> [local count: 118111600]:
# e_7 = PHI <0(2), e_3(3)>
<bb 6> [local count: 1073741824]:
# e_4 = PHI <e_7(5), e_4(4)>
a.1_6 = a;
if (a.1_6 != 0)
goto <bb 4>; [89.00%]
else
goto <bb 7>; [11.00%]
```
Notice how e_4 is used in e_4.
```
Uses of e_7 will be replaced by e_9
Replacing e_7 = PHI <0(2), e_3(3)>
with e_9 = PHI <0(2), _2(3)>
Uses of e_4 will be replaced by e_8
Replacing e_4 = PHI <e_7(4), e_4(7)>
with e_8 = PHI <e_9(4), e_8(7)>
Deleting e_8 = PHI <e_9(4), e_8(7)>
Uses of e_4 will be replaced by e_9
Deleting e_9 = PHI <0(2), _2(3)>
```
We deleted e_8 and e_9 and I think it is trying to delete e_8 phi again.
