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From: "ebotcazou at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/37377] [4.4 Regression] Bootstrap failure compiling libgcc Date: Mon, 08 Sep 2008 15:27:00 -0000 [thread overview] Message-ID: <20080908152544.17188.qmail@sourceware.org> (raw) In-Reply-To: <bug-37377-226@http.gcc.gnu.org/bugzilla/> ------- Comment #12 from ebotcazou at gcc dot gnu dot org 2008-09-08 15:25 ------- > Eric, thanks a lot for your analysis. It was very helpful. You're welcome! > IRA uses live ranges to find conflicts for spill slots during reload. Live > ranges for r376 were wrong after IR flattening. We have the following loop > structure for the case > > l8->l7->l0 > ^ > l24->l22-| > > and we remove mem<-reg coping allocno values from l8 to l0 because allocnos > corresponding to r376 are not modified in the loops. Allocno for r376 in l0 > got live ranges only from l8 and l7 but not from l22 ... Therefore IRA does > not find conflicts with another allocno (r90) in l22 and l24. Yes, my understanding was that the flattening code currently assumes that the moves are always generated at the borders. > I'll send a patch to solve the problem today. Just removing the optimization > (removing unnecessary mem<-reg) is not wise because it has significant impact > on the generated code performance. OK, thanks for the explanation. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37377
next prev parent reply other threads:[~2008-09-08 15:27 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2008-09-04 20:23 [Bug rtl-optimization/37377] New: " ebotcazou at gcc dot gnu dot org 2008-09-04 20:31 ` [Bug rtl-optimization/37377] " ebotcazou at gcc dot gnu dot org 2008-09-04 20:33 ` ebotcazou at gcc dot gnu dot org 2008-09-04 20:37 ` ebotcazou at gcc dot gnu dot org 2008-09-04 20:47 ` ebotcazou at gcc dot gnu dot org 2008-09-05 4:48 ` hjl dot tools at gmail dot com 2008-09-05 6:25 ` ebotcazou at gcc dot gnu dot org 2008-09-05 13:48 ` hjl dot tools at gmail dot com 2008-09-07 14:00 ` ebotcazou at gcc dot gnu dot org 2008-09-07 15:47 ` ebotcazou at gcc dot gnu dot org 2008-09-07 16:02 ` ebotcazou at gcc dot gnu dot org 2008-09-08 14:12 ` vmakarov at redhat dot com 2008-09-08 15:27 ` ebotcazou at gcc dot gnu dot org [this message] 2008-09-09 0:04 ` hjl at gcc dot gnu dot org 2008-09-12 22:58 ` vmakarov at gcc dot gnu dot org 2008-09-13 8:52 ` ebotcazou at gcc dot gnu dot org 2008-09-18 19:58 ` pinskia at gcc dot gnu dot org 2009-04-11 19:48 ` tkoenig at gcc dot gnu dot org
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