https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100801
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|ipa |tree-optimization
Keywords| |diagnostic,
| |missed-optimization
Status|UNCONFIRMED |ASSIGNED
Ever confirmed|0 |1
Last reconfirmed| |2021-05-28
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot
gnu.org
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed. We're warning on the obviously unreachable loop since:
<bb 4> [local count: 1073741824]:
_35 = 12;
if (_35 != 12)
goto <bb 7>; [75.00%]
else
goto <bb 6>; [25.00%]
$3 = <basic_block 0x7ffff434b680 (4)>
since we apply final value replacement to 'i' in sccp but do not propagate it
before the next number of iteration analysis in ivcanon:
NEXT_PASS (pass_tree_loop_init);
NEXT_PASS (pass_tree_unswitch);
NEXT_PASS (pass_scev_cprop); <<<< final value repl.
NEXT_PASS (pass_loop_split);
NEXT_PASS (pass_loop_versioning);
NEXT_PASS (pass_loop_jam);
/* All unswitching, final value replacement and splitting can expose
empty loops. Remove them now. */
NEXT_PASS (pass_cd_dce, false /* update_address_taken_p */);
NEXT_PASS (pass_iv_canon); <<<<< warning
NEXT_PASS (pass_loop_distribution);
NEXT_PASS (pass_linterchange);
NEXT_PASS (pass_copy_prop); <<<<<< propagation
IIRC final value replacement used to propagate and fold but I(?) removed this
at some point.
