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From: "steven at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/42906] [4.5 Regression] Empty loop not removed Date: Sat, 30 Jan 2010 16:37:00 -0000 [thread overview] Message-ID: <20100130163737.12628.qmail@sourceware.org> (raw) In-Reply-To: <bug-42906-10053@http.gcc.gnu.org/bugzilla/> ------- Comment #1 from steven at gcc dot gnu dot org 2010-01-30 16:37 ------- The loop is deemed necessary because the loop block (bb 6) is control dependent on itself (?!): (gdb) mark_control_dependent_edges_necessary (bb=0x7ffff7f264e0, el=0x142c5d0) at ../../trunk/gcc/tree-ssa-dce.c:388 388 EXECUTE_IF_CONTROL_DEPENDENT (bi, bb->index, edge_number) (gdb) 391 basic_block cd_bb = INDEX_EDGE_PRED_BB (el, edge_number); (gdb) 393 if (TEST_BIT (last_stmt_necessary, cd_bb->index)) (gdb) p debug_bb(cd_bb) ;; basic block 6, loop depth 1, count 0 ;; prev block 3, next block 5 ;; pred: 4 [100.0%] (fallthru) 3 (fallthru,dfs_back,exec) ;; succ: 3 (true,exec) 5 (false,exec) <bb 6>: # i_2 = PHI <i_8(4), i_6(3)> if (i_2 <= 999) goto <bb 3>; else goto <bb 5>; $22 = void (gdb) p debug_bb(bb) ;; basic block 6, loop depth 1, count 0 ;; prev block 3, next block 5 ;; pred: 4 [100.0%] (fallthru) 3 (fallthru,dfs_back,exec) ;; succ: 3 (true,exec) 5 (false,exec) <bb 6>: # i_2 = PHI <i_8(4), i_6(3)> if (i_2 <= 999) goto <bb 3>; else goto <bb 5>; $23 = void (gdb) -- steven at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Ever Confirmed|0 |1 Last reconfirmed|0000-00-00 00:00:00 |2010-01-30 16:37:37 date| | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42906
next prev parent reply other threads:[~2010-01-30 16:37 UTC|newest] Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2010-01-30 16:06 [Bug tree-optimization/42906] New: " rguenth at gcc dot gnu dot org 2010-01-30 16:06 ` [Bug tree-optimization/42906] " rguenth at gcc dot gnu dot org 2010-01-30 16:37 ` steven at gcc dot gnu dot org [this message] 2010-01-30 16:42 ` steven at gcc dot gnu dot org 2010-01-30 16:46 ` steven at gcc dot gnu dot org 2010-01-30 16:51 ` steven at gcc dot gnu dot org 2010-01-30 16:53 ` rguenth at gcc dot gnu dot org 2010-01-30 16:55 ` rguenth at gcc dot gnu dot org 2010-01-30 16:58 ` rguenth at gcc dot gnu dot org 2010-01-30 16:58 ` rguenth at gcc dot gnu dot org 2010-01-30 17:31 ` steven at gcc dot gnu dot org 2010-01-30 20:32 ` steven at gcc dot gnu dot org 2010-01-30 20:56 ` rguenth at gcc dot gnu dot org 2010-01-30 21:12 ` rguenth at gcc dot gnu dot org 2010-01-30 23:04 ` rguenth at gcc dot gnu dot org 2010-01-30 23:15 ` steven at gcc dot gnu dot org 2010-02-02 13:31 ` rguenth at gcc dot gnu dot org 2010-02-16 19:54 ` changpeng dot fang at amd dot com 2010-02-16 19:57 ` pinskia at gcc dot gnu dot org 2010-03-17 0:19 ` changpeng dot fang at amd dot com 2010-03-17 0:22 ` changpeng dot fang at amd dot com 2010-03-17 10:01 ` rguenther at suse dot de 2010-03-18 17:24 ` changpeng dot fang at amd dot com 2010-03-18 17:30 ` rguenther at suse dot de 2010-03-24 18:18 ` hubicka at gcc dot gnu dot org 2010-03-24 19:02 ` hubicka at gcc dot gnu dot org 2010-03-25 17:23 ` hubicka at ucw dot cz 2010-03-27 18:31 ` hubicka at gcc dot gnu dot org 2010-04-06 11:26 ` rguenth at gcc dot gnu dot org 2010-04-06 11:38 ` hubicka at ucw dot cz 2010-04-06 15:19 ` hubicka at gcc dot gnu dot org 2010-07-31 9:35 ` rguenth at gcc dot gnu dot org [not found] <bug-42906-4@http.gcc.gnu.org/bugzilla/> 2010-12-16 13:05 ` rguenth at gcc dot gnu.org 2011-04-28 15:15 ` rguenth at gcc dot gnu.org 2012-03-23 15:34 ` hubicka at gcc dot gnu.org 2012-07-02 10:29 ` rguenth at gcc dot gnu.org
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