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From: "krebbel at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/101523] Huge number of combine attempts Date: Tue, 20 Jul 2021 09:41:38 +0000 [thread overview] Message-ID: <bug-101523-4-Ep4nnCR1uk@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-101523-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101523 --- Comment #1 from Andreas Krebbel <krebbel at gcc dot gnu.org> --- This appears to be triggered by try_combine unnecessarily setting back the position by returning the i2 insn. When 866 is inserted into 973 866 still needs to be kept around for other users. So try_combine first merges the two sets into a parallel and immediately notices that this can't be recognized. Because none of the sets is a trivial move it is split again into two separate insns. Although the new i2 pattern exactly matches the input i2 combine considers this to be a new insn and triggers all the scanning log link creation and eventually returns it what let's the combine start all over at 866. Due to that combine tries many of the substitutions more than 400x. Trying 866 -> 973: 866: r22393:DI=r22391:DI+r22392:DI 973: r22499:DF=r22498:DF*[r22393:DI] REG_DEAD r22498:DF Failed to match this instruction: (parallel [ (set (reg:DF 22499) (mult:DF (reg:DF 22498) (mem:DF (plus:DI (reg/f:DI 22391 [ _85085 ]) (reg:DI 22392 [ _85086 ])) [17 *_85087+0 S8 A64]))) (set (reg/f:DI 22393 [ _85087 ]) (plus:DI (reg/f:DI 22391 [ _85085 ]) (reg:DI 22392 [ _85086 ]))) ]) Failed to match this instruction: (parallel [ (set (reg:DF 22499) (mult:DF (reg:DF 22498) (mem:DF (plus:DI (reg/f:DI 22391 [ _85085 ]) (reg:DI 22392 [ _85086 ])) [17 *_85087+0 S8 A64]))) (set (reg/f:DI 22393 [ _85087 ]) (plus:DI (reg/f:DI 22391 [ _85085 ]) (reg:DI 22392 [ _85086 ]))) ]) Successfully matched this instruction: (set (reg/f:DI 22393 [ _85087 ]) (plus:DI (reg/f:DI 22391 [ _85085 ]) (reg:DI 22392 [ _85086 ]))) Successfully matched this instruction: (set (reg:DF 22499) (mult:DF (reg:DF 22498) (mem:DF (plus:DI (reg/f:DI 22391 [ _85085 ]) (reg:DI 22392 [ _85086 ])) [17 *_85087+0 S8 A64]))) allowing combination of insns 866 and 973 original costs 4 + 4 = 8 replacement costs 4 + 4 = 8 modifying insn i2 866: r22393:DI=r22391:DI+r22392:DI deferring rescan insn with uid = 866. modifying insn i3 973: r22499:DF=r22498:DF*[r22391:DI+r22392:DI] REG_DEAD r22498:DF deferring rescan insn with uid = 973.
next prev parent reply other threads:[~2021-07-20 9:41 UTC|newest] Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-20 9:35 [Bug rtl-optimization/101523] New: " krebbel at gcc dot gnu.org 2021-07-20 9:41 ` krebbel at gcc dot gnu.org [this message] 2021-07-20 9:42 ` [Bug rtl-optimization/101523] " krebbel at gcc dot gnu.org 2021-07-20 21:27 ` segher at gcc dot gnu.org 2024-02-24 5:45 ` krebbel at gcc dot gnu.org 2024-02-25 10:53 ` segher at gcc dot gnu.org 2024-02-25 15:06 ` segher at gcc dot gnu.org 2024-03-02 18:43 ` sarah.kriesch at opensuse dot org 2024-03-02 21:04 ` sjames at gcc dot gnu.org 2024-03-03 19:32 ` segher at gcc dot gnu.org 2024-03-04 8:18 ` krebbel at gcc dot gnu.org 2024-03-04 16:31 ` segher at gcc dot gnu.org 2024-03-04 16:49 ` sarah.kriesch at opensuse dot org 2024-03-04 21:26 ` segher at gcc dot gnu.org 2024-03-05 7:31 ` krebbel at gcc dot gnu.org 2024-03-05 10:36 ` sarah.kriesch at opensuse dot org 2024-03-06 22:49 ` segher at gcc dot gnu.org 2024-03-06 22:53 ` segher at gcc dot gnu.org 2024-03-06 23:15 ` pinskia at gcc dot gnu.org 2024-03-07 9:26 ` krebbel at gcc dot gnu.org 2024-03-07 9:28 ` krebbel at gcc dot gnu.org 2024-03-07 9:34 ` krebbel at gcc dot gnu.org 2024-03-07 15:51 ` krebbel at gcc dot gnu.org 2024-03-07 15:52 ` krebbel at gcc dot gnu.org 2024-03-07 16:11 ` segher at gcc dot gnu.org 2024-03-07 16:19 ` segher at gcc dot gnu.org 2024-03-07 16:53 ` pinskia at gcc dot gnu.org 2024-03-07 16:57 ` pinskia at gcc dot gnu.org 2024-03-07 18:15 ` segher at gcc dot gnu.org 2024-03-07 19:42 ` segher at gcc dot gnu.org 2024-03-07 19:45 ` jakub at gcc dot gnu.org 2024-03-07 20:10 ` segher at gcc dot gnu.org 2024-03-07 20:17 ` krebbel at gcc dot gnu.org 2024-03-07 20:53 ` krebbel at gcc dot gnu.org 2024-03-20 11:53 ` [Bug target/101523] " rguenth at gcc dot gnu.org 2024-03-21 7:56 ` segher at gcc dot gnu.org 2024-03-21 8:15 ` rguenth at gcc dot gnu.org 2024-03-21 8:27 ` rguenth at gcc dot gnu.org 2024-03-21 12:57 ` segher at gcc dot gnu.org 2024-03-21 12:58 ` segher at gcc dot gnu.org 2024-03-21 13:15 ` rguenth at gcc dot gnu.org 2024-03-21 13:22 ` rguenth at gcc dot gnu.org 2024-03-22 8:07 ` rguenth at gcc dot gnu.org 2024-03-22 9:41 ` rguenth at gcc dot gnu.org 2024-03-22 9:42 ` sjames at gcc dot gnu.org 2024-03-22 9:42 ` sjames at gcc dot gnu.org 2024-03-22 9:52 ` rguenth at gcc dot gnu.org 2024-03-22 12:17 ` rguenth at gcc dot gnu.org 2024-03-22 12:38 ` rguenth at gcc dot gnu.org 2024-03-27 14:35 ` sarah.kriesch at opensuse dot org 2024-03-27 16:10 ` [Bug rtl-optimization/101523] " cvs-commit at gcc dot gnu.org 2024-03-27 16:53 ` segher at gcc dot gnu.org 2024-03-27 16:55 ` segher at gcc dot gnu.org 2024-04-03 10:58 ` rguenth at gcc dot gnu.org 2024-04-05 11:48 ` segher at gcc dot gnu.org 2024-04-05 12:20 ` rguenth at gcc dot gnu.org 2024-04-10 6:02 ` rguenth at gcc dot gnu.org 2024-04-10 15:51 ` segher at gcc dot gnu.org 2024-04-10 15:57 ` jakub at gcc dot gnu.org 2024-04-10 17:03 ` rguenth at gcc dot gnu.org 2024-04-10 17:45 ` sarah.kriesch at opensuse dot org 2024-05-04 6:00 ` segher at gcc dot gnu.org 2024-05-04 13:14 ` sarah.kriesch at opensuse dot org 2024-05-04 17:30 ` segher at gcc dot gnu.org 2024-05-06 9:21 ` rguenther at suse dot de 2024-05-06 9:40 ` segher at kernel dot crashing.org 2024-05-06 9:42 ` segher at gcc dot gnu.org 2024-05-06 9:46 ` rguenth at gcc dot gnu.org
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