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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/97225] Failure to optimize out conditional addition of zero Date: Mon, 28 Sep 2020 11:18:31 +0000 [thread overview] Message-ID: <bug-97225-4-Fs7A73i7EQ@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-97225-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97225 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2020-09-28 Component|c |tree-optimization Keywords| |missed-optimization Ever confirmed|0 |1 Status|UNCONFIRMED |NEW --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- I think we've seen a duplicate report for this. Confirmed. late phiopt sees (we need hoisting to get rid of the loads in the two if arms): <bb 2> [local count: 1073741824]: _1 = vec_6(D)->size; pretmp_9 = vec_6(D)->data; if (_1 == 0) goto <bb 4>; [34.00%] else goto <bb 3>; [66.00%] <bb 3> [local count: 708669601]: _3 = _1 * 4; _7 = pretmp_9 + _3; <bb 4> [local count: 1073741824]: # _4 = PHI <_7(3), pretmp_9(2)> return _4; where it misses the value-conversion, possibly either based on lack of handling the mult+add or because of consideration of making the not infrequent path more expensive. Later if-converting this anyway on RTL shows a disconnect in cost then.
next prev parent reply other threads:[~2020-09-28 11:18 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-09-28 10:22 [Bug c/97225] New: " osandov at osandov dot com 2020-09-28 11:18 ` rguenth at gcc dot gnu.org [this message] 2020-09-30 16:36 ` [Bug tree-optimization/97225] " pinskia at gcc dot gnu.org 2023-08-04 22:28 ` pinskia at gcc dot gnu.org
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