https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100145
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|tree-optimization |ipa
Keywords| |missed-optimization
Ever confirmed|0 |1
Last reconfirmed| |2021-04-20
CC| |hubicka at gcc dot gnu.org,
| |marxin at gcc dot gnu.org,
| |rguenth at gcc dot gnu.org
Status|UNCONFIRMED |NEW
Version|unknown |11.0
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
At -O2 we optimize things in thread3, at -O3 we have a PHI less there and thus
do no backwards threading which is because 'c' wasn't PREd for some reason
(-fno-tree-vectorize or -fno-tree-partial-pre do not help)
int main ()
{
- int D.2001;
- int b.1_7;
- int prephitmp_16;
+ int _1;
+ int b.1_6;
<bb 2> [local count: 1073741824]:
c = 0;
- b.1_7 = b;
- if (b.1_7 != 0)
+ b.1_6 = b;
+ if (b.1_6 != 0)
goto <bb 3>; [34.00%]
else
goto <bb 4>; [66.00%]
- <bb 3> [local count: 3318838410]:
+ <bb 3> [local count: 365072224]:
c = 1;
<bb 4> [local count: 1073741824]:
- # prephitmp_16 = PHI <0(2), 1(3)>
d = 1;
- if (prephitmp_16 > 100)
+ _1 = c;
+ if (_1 > 100)
goto <bb 5>; [33.00%]
else
goto <bb 6>; [67.00%]
the issue seems to be the guessed profile (but BB counts are the same!):
+Skipping partial redundancy for expression {mem_ref<0B>,addr_expr<&c>}@.MEM_7
(
0001), no redundancy on to be optimized for speed edge
so that leaves the "global" hot count we IPA compute somehow? Honza?
