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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 tree-optimization/33604] [4.3 Regression] Revision 119502 causes significantly slower results with 4.3 compared to 4.2 Date: Wed, 07 Nov 2007 17:28:00 -0000 [thread overview] Message-ID: <20071107172811.10636.qmail@sourceware.org> (raw) In-Reply-To: <bug-33604-15171@http.gcc.gnu.org/bugzilla/> ------- Comment #20 from rguenth at gcc dot gnu dot org 2007-11-07 17:28 ------- Basically things like D.2196_13 = (struct Ref *) &D.2150.lhs; D.2196_13->m ={v} &I; where D.2150.lhs is const and thus there is a (not useless) cast from (const struct Ref *) to (struct Ref *). So what the code does is to store to "const" qualified memory: D.2150.lhs.m = &I; of course only as part of constructing it, so it is legal, but the middle-end cannot tell apart legal from illegal cases. So we can just declare all of them legal based on the fact that otherwise this would certainly invoke undefined behavior. In which case tree-level forwprop can be teached to disregard conversions that change constness only on address-forwarding. Something like a more careful Index: tree-ssa-forwprop.c =================================================================== --- tree-ssa-forwprop.c (revision 129897) +++ tree-ssa-forwprop.c (working copy) @@ -952,8 +952,14 @@ tree_ssa_forward_propagate_single_use_va continue; } - if (TREE_CODE (rhs) == ADDR_EXPR) + if (TREE_CODE (rhs) == ADDR_EXPR + || ((TREE_CODE (rhs) == NOP_EXPR + || TREE_CODE (rhs) == CONVERT_EXPR) + && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR + && (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (rhs))) + == TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (TREE_OPERAND (rhs, 0))))))) { + STRIP_NOPS (rhs); if (forward_propagate_addr_expr (lhs, rhs)) { release_defs (stmt); -- rguenth at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot |dot org |org Status|NEW |ASSIGNED Last reconfirmed|2007-11-07 13:09:53 |2007-11-07 17:28:11 date| | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33604
next prev parent reply other threads:[~2007-11-07 17:28 UTC|newest] Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top 2007-09-30 21:13 [Bug c++/33604] New: " michael dot olbrich at gmx dot net 2007-09-30 21:15 ` [Bug c++/33604] " michael dot olbrich at gmx dot net 2007-10-01 9:47 ` rguenth at gcc dot gnu dot org 2007-10-01 21:03 ` [Bug c++/33604] [4.3 Regression] Revision 119502 causes " hjl at lucon dot org 2007-10-01 21:04 ` hjl at lucon dot org 2007-10-01 21:07 ` Daniel Berlin 2007-10-01 21:07 ` dberlin at dberlin dot org 2007-10-22 8:33 ` pinskia at gcc dot gnu dot org 2007-11-05 1:47 ` mmitchel at gcc dot gnu dot org 2007-11-06 17:10 ` bonzini at gnu dot org 2007-11-06 18:55 ` michael dot olbrich at gmx dot net 2007-11-06 20:08 ` bonzini at gnu dot org 2007-11-06 21:01 ` michael dot olbrich at gmx dot net 2007-11-06 21:23 ` bonzini at gnu dot org 2007-11-06 21:51 ` [Bug tree-optimization/33604] " rguenth at gcc dot gnu dot org 2007-11-07 6:03 ` paolo dot bonzini at lu dot unisi dot ch 2007-11-07 12:14 ` dnovillo at google dot com 2007-11-07 13:09 ` bonzini at gnu dot org 2007-11-07 13:10 ` bonzini at gnu dot org 2007-11-07 14:22 ` bonzini at gnu dot org 2007-11-07 16:03 ` bonzini at gnu dot org 2007-11-07 16:26 ` bonzini at gnu dot org 2007-11-07 16:36 ` bonzini at gnu dot org 2007-11-07 17:28 ` rguenth at gcc dot gnu dot org [this message] 2007-11-07 20:59 ` jacob at math dot jussieu dot fr 2007-11-08 6:12 ` paolo dot bonzini at lu dot unisi dot ch 2007-11-09 12:32 ` rguenth at gcc dot gnu dot org 2007-11-09 12:33 ` rguenth at gcc dot gnu dot org 2007-11-09 12:49 ` jacob at math dot jussieu dot fr 2007-11-09 12:52 ` rguenther at suse dot de 2007-11-09 12:56 ` jacob at math dot jussieu dot fr 2007-12-04 10:56 ` michael dot olbrich at gmx dot net 2007-12-04 11:18 ` bonzini at gnu dot org 2007-12-04 11:21 ` rguenth at gcc dot gnu dot org 2007-12-04 12:17 ` michael dot olbrich at gmx dot net 2007-12-04 12:38 ` paolo dot bonzini at lu dot unisi dot ch 2008-01-02 11:17 ` rguenth at gcc dot gnu dot org 2008-02-27 16:36 ` [Bug tree-optimization/33604] [4.3/4.4 Regression] Revision 119502 causes significantly slower results with 4.3/4.4 " jacob at math dot jussieu dot fr 2008-02-27 16:44 ` [Bug target/33604] " pinskia at gcc dot gnu dot org 2008-02-27 16:59 ` jacob at math dot jussieu dot fr 2008-02-27 17:06 ` bonzini at gnu dot org 2008-03-02 12:15 ` michael dot olbrich at gmx dot net 2008-03-02 12:27 ` bonzini at gnu dot org 2008-03-02 14:01 ` rguenth at gcc dot gnu dot org 2008-03-14 17:03 ` rguenth at gcc dot gnu dot org 2008-06-06 15:00 ` rguenth at gcc dot gnu dot org 2008-08-27 22:05 ` jsm28 at gcc dot gnu dot org 2008-08-29 13:14 ` amonakov at gcc dot gnu dot org 2008-12-25 18:14 ` pinskia at gcc dot gnu dot org 2008-12-30 1:50 ` Joey dot ye at intel dot com 2008-12-30 8:04 ` bonzini at gnu dot org 2009-01-24 10:28 ` rguenth at gcc dot gnu dot org 2009-02-01 8:14 ` bonzini at gnu dot org 2009-02-01 10:45 ` rguenth at gcc dot gnu dot org
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