https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84650
--- Comment #3 from amker at gcc dot gnu.org ---
So given below dump before sccp:
<bb 2> [local count: 14598063]:
<bb 3> [local count: 118111601]:
# eu_19 = PHI <0(2), eu_13(7)>
<bb 4> [local count: 955630224]:
# dj.1_18 = PHI <0(3), _1(8)>
_1 = dj.1_18 + 1;
if (_1 <= 1)
goto <bb 8>; [89.00%]
else
goto <bb 5>; [11.00%]
<bb 8> [local count: 850510900]:
goto <bb 4>; [100.00%]
<bb 5> [local count: 118111601]:
# _2 = PHI <_1(4)>
_4 = _2 != 3;
_5 = (unsigned int) _4;
_15 = 1 - _5;
eu_13 = _15 + eu_19;
if (eu_13 <= 1)
goto <bb 7>; [87.64%]
else
goto <bb 6>; [12.36%]
<bb 7> [local count: 103513538]:
goto <bb 3>; [100.00%]
<bb 6> [local count: 14598063]:
# _25 = PHI <_2(5)>
dj = _25;
return;
before sccp, e_13, _15 and e_19 was identified as:
e_13: {_15, _15}
_15 : _15
e_19: {0, _15}
During sccp, it proves _15 equals to 0 and thus:
e_13: 0
_15 : 0
e_19: {0, _15}
This information is cached and used in ivopts.
