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From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/41004] missed merge of basic blocks Date: Sat, 08 Aug 2009 10:36:00 -0000 [thread overview] Message-ID: <20090808103619.26500.qmail@sourceware.org> (raw) In-Reply-To: <bug-41004-17659@http.gcc.gnu.org/bugzilla/> ------- Comment #3 from rguenth at gcc dot gnu dot org 2009-08-08 10:36 ------- I would suggest to closely look at SSA expansion as well. There is I think still the regression from pre-SSA expand that it doesn't expand PHI nodes optimally at -Os (pre-SSA expand split common PHI args into extra blocks to minimize copy instructions which is something that can be done as a tree level transform). Like BB5: # a_1 = PHI <a_2(2), a_2(3), b_3(4)> to BB6: # tmp_4 = PHI <a_2(2), a_2(3)> BB5: # a_1 = PHI <tmp_4(6), b_3(4)> which we usually don't want and in fact undo during mergephi. But it needs one less copy if a_2 and tmp_4 can be coalesced together. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41004
next prev parent reply other threads:[~2009-08-08 10:36 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-08-08 0:10 [Bug target/41004] New: " carrot at google dot com 2009-08-08 0:10 ` [Bug target/41004] " carrot at google dot com 2009-08-08 9:07 ` steven at gcc dot gnu dot org 2009-08-08 10:07 ` [Bug middle-end/41004] " steven at gcc dot gnu dot org 2009-08-08 10:36 ` rguenth at gcc dot gnu dot org [this message] 2009-08-19 21:55 ` carrot at google dot com 2009-08-19 23:07 ` rth at gcc dot gnu dot org 2010-01-11 9:36 ` steven at gcc dot gnu dot org [not found] <bug-41004-4@http.gcc.gnu.org/bugzilla/> 2012-02-04 3:01 ` pinskia at gcc dot gnu.org 2012-03-17 0:02 ` steven at gcc dot gnu.org 2012-11-08 23:07 ` steven at gcc dot gnu.org 2012-11-09 21:38 ` steven at gcc dot gnu.org
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