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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/64164] [4.9/5 Regression] one more stack slot used due to one less inlining level Date: Wed, 03 Dec 2014 10:03:00 -0000 [thread overview] Message-ID: <bug-64164-4-dIk5C5mUZM@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-64164-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64164 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |missed-optimization Last reconfirmed|2014-12-03 00:00:00 | Component|middle-end |rtl-optimization Target Milestone|--- |4.9.3 --- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- The difference is in whether there are extra user-named variables in the end and thus SSA coalescing decision differences: stm_load (volatile stm_word_t * addr) { - stm_word_t l; - stm_word_t value; stm_word_t version; stm_word_t l; struct r_entry_t * r; - stm_word_t now; ... + size_t _32; + size_t _33; + size_t _34; ... Conflict graph: +1: 3 +3: 1 After sorting: Sorted Coalesce list: +(16610) _30 <-> _33 (651) _10 <-> _30 ... -Coalesce list: (10)_10 & (30)_30 [map: 1, 2] : Success -> 1 +Coalesce list: (30)_30 & (33)_33 [map: 2, 3] : Success -> 2 +Coalesce list: (10)_10 & (30)_30 [map: 1, 2] : Fail due to conflict So it turns out the different coalescing ends up generating worse code. It would be interesting to see why we decide that coalescing _30 and _33 is so much more beneficial than coalescing _10 and _30. Ah, it simply uses EDGE_FREQUENCY... and for some reason we predicted that _33 & 1 != 0 is 10% taken only. So ... the theory is that the version is faster on the important path?
next prev parent reply other threads:[~2014-12-03 10:03 UTC|newest] Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-12-03 9:33 [Bug ipa/64164] New: " patrick.marlier at gmail dot com 2014-12-03 9:44 ` [Bug middle-end/64164] " pinskia at gcc dot gnu.org 2014-12-03 9:45 ` pinskia at gcc dot gnu.org 2014-12-03 10:03 ` rguenth at gcc dot gnu.org [this message] 2014-12-03 10:06 ` [Bug rtl-optimization/64164] " rguenth at gcc dot gnu.org 2014-12-11 11:46 ` rguenth at gcc dot gnu.org 2014-12-17 11:38 ` patrick.marlier at gmail dot com 2015-03-17 18:19 ` law at redhat dot com 2015-03-17 19:55 ` amacleod at redhat dot com 2015-03-17 22:15 ` aoliva at gcc dot gnu.org 2015-03-17 22:18 ` aoliva at gcc dot gnu.org 2015-03-17 22:19 ` aoliva at gcc dot gnu.org 2015-03-17 23:01 ` aoliva at gcc dot gnu.org 2015-03-18 0:20 ` aoliva at gcc dot gnu.org 2015-03-18 5:48 ` law at redhat dot com 2015-03-18 9:02 ` rguenth at gcc dot gnu.org 2015-03-18 9:03 ` rguenth at gcc dot gnu.org 2015-03-18 9:19 ` rguenth at gcc dot gnu.org 2015-03-18 10:05 ` aoliva at gcc dot gnu.org 2015-03-18 10:16 ` rguenther at suse dot de 2015-03-18 10:18 ` aoliva at gcc dot gnu.org 2015-03-19 5:17 ` aoliva at gcc dot gnu.org 2015-03-20 8:07 ` law at redhat dot com 2015-03-20 10:03 ` rguenther at suse dot de 2015-03-20 20:44 ` law at redhat dot com 2015-03-27 18:26 ` aoliva at gcc dot gnu.org 2015-03-29 20:58 ` aoliva at gcc dot gnu.org 2015-03-30 23:06 ` patrick.marlier at gmail dot com 2015-03-30 23:09 ` law at redhat dot com 2015-03-30 23:34 ` law at redhat dot com 2015-03-31 12:21 ` rguenth at gcc dot gnu.org 2015-03-31 12:21 ` [Bug rtl-optimization/64164] [4.9/5/6 " rguenth at gcc dot gnu.org 2015-03-31 12:56 ` jakub at gcc dot gnu.org 2015-04-01 7:51 ` rguenth at gcc dot gnu.org 2015-06-09 5:06 ` aoliva at gcc dot gnu.org 2015-06-09 5:34 ` [Bug rtl-optimization/64164] [4.9/5 " aoliva at gcc dot gnu.org 2015-06-09 9:10 ` ebotcazou at gcc dot gnu.org 2015-06-09 16:35 ` dje at gcc dot gnu.org 2015-06-10 0:15 ` [Bug rtl-optimization/64164] [4.9/5/6 " aoliva at gcc dot gnu.org 2015-06-10 13:16 ` clyon at gcc dot gnu.org 2015-06-10 14:43 ` dje at gcc dot gnu.org 2015-06-10 14:45 ` dje at gcc dot gnu.org 2015-07-23 15:35 ` aoliva at gcc dot gnu.org 2015-07-24 10:37 ` schwab@linux-m68k.org 2015-07-24 10:51 ` schwab@linux-m68k.org 2015-07-24 16:57 ` sje at gcc dot gnu.org 2015-07-27 9:07 ` ro at gcc dot gnu.org 2015-07-30 18:20 ` aoliva at gcc dot gnu.org 2015-08-02 21:11 ` gary at intrepid dot com 2015-08-14 18:52 ` aoliva at gcc dot gnu.org 2015-08-15 2:24 ` aoliva at gcc dot gnu.org 2015-08-15 2:25 ` aoliva at gcc dot gnu.org 2015-08-15 2:25 ` aoliva at gcc dot gnu.org 2015-08-15 2:26 ` aoliva at gcc dot gnu.org 2015-08-15 2:26 ` aoliva at gcc dot gnu.org 2015-08-15 2:27 ` aoliva at gcc dot gnu.org 2015-08-19 17:01 ` aoliva at gcc dot gnu.org 2015-08-21 20:04 ` aoliva at gcc dot gnu.org 2015-08-21 20:05 ` aoliva at gcc dot gnu.org 2015-09-23 21:13 ` aoliva at gcc dot gnu.org 2015-09-27 9:03 ` aoliva at gcc dot gnu.org 2015-09-27 12:13 ` trippels at gcc dot gnu.org 2015-09-28 1:15 ` aoliva at gcc dot gnu.org 2015-09-28 1:16 ` aoliva at gcc dot gnu.org 2015-09-28 1:16 ` aoliva at gcc dot gnu.org 2015-10-09 12:21 ` aoliva at gcc dot gnu.org 2015-10-09 12:22 ` aoliva at gcc dot gnu.org
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