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From: Jan Hubicka <hubicka@ucw.cz>
To: "sergos.gnu at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
Cc: gcc-bugs@gcc.gnu.org
Subject: Re: [Bug tree-optimization/54717] [4.8 Regression] Runtime regression: polyhedron test "rnflow" degraded
Date: Wed, 14 Nov 2012 19:42:00 -0000 [thread overview]
Message-ID: <20121114194241.GB13739@atrey.karlin.mff.cuni.cz> (raw)
In-Reply-To: <bug-54717-4-E0Y07b6dLY@http.gcc.gnu.org/bugzilla/>
> So for the loop that starting at bb 28 you can see the xxtrt_46 access was not
> put into pretemp. Possible reason is exactly as it was mentioned by Richard -
> there were extra candidates collected and this one become less anticipatable
>
> Skipping partial partial redundancy for expression
> {array_ref<pretmp_8,0,4>,mem_ref<0B>,xxtrt_46(D)}@.MEM_30(D) (0165)
> not partially anticipated on any to be optimized for speed edges
> -----------------------------------------------------------------------
> Found partial partial redundancy for expression
> {array_ref<pretmp_8,0,4>,mem_ref<0B>,xxtrt_46(D)}@.MEM_30(D) (0165)
> Created phi prephitmp_237 = PHI <_88(90), _85(29)>
> in block 30
Hmm, interesting, what is the edge resonsible?
I would expect it to be the loopback edge and its frequency is:
;; basic block 28, loop depth 0, count 0, freq 1998, maybe hot
;; prev block 92, next block 94, flags: (NEW, REACHABLE)
;; pred: 92 [100.0%, 180] (FALLTHRU)
;; 96 [100.0%, 1818] (FALLTHRU,DFS_BACK)
# ival2_136 = PHI <ival2_62(92), ival2_144(96)>
# ival2_140 = PHI <ival2_80(92), ival2_146(96)>
_137 = (integer(kind=8)) ival2_136;
_138 = _137 + -1;
_139 = *xxtrt_25(D)[_138];
_141 = (integer(kind=8)) ival2_140;
_142 = _141 + -1;
_143 = *xxtrt_25(D)[_142];
if (_139 < _143)
goto <bb 29>;
else
goto <bb 94>;
1818 that should be still hot. Or isn't the heuristic backwards? I.e. I would expect
the partial anticipance to sit on edge 92->28 (with freq 180) where we need to insert
the computation to get the other path hot.
Honza
next prev parent reply other threads:[~2012-11-14 19:42 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-26 12:54 [Bug tree-optimization/54717] New: " sergos.gnu at gmail dot com
2012-09-26 13:17 ` [Bug tree-optimization/54717] " ubizjak at gmail dot com
2012-09-26 14:17 ` [Bug tree-optimization/54717] [4.8 Regression] " rguenth at gcc dot gnu.org
2012-09-26 15:12 ` sergos.gnu at gmail dot com
2012-09-26 15:41 ` dominiq at lps dot ens.fr
2012-09-26 20:07 ` sergos.gnu at gmail dot com
2012-09-27 9:28 ` rguenth at gcc dot gnu.org
2012-09-27 10:43 ` rguenth at gcc dot gnu.org
2012-10-02 20:24 ` dominiq at lps dot ens.fr
2012-10-08 8:55 ` sergos.gnu at gmail dot com
2012-11-13 18:40 ` ubizjak at gmail dot com
2012-11-13 18:54 ` dominiq at lps dot ens.fr
2012-11-14 18:56 ` sergos.gnu at gmail dot com
2012-11-14 19:42 ` Jan Hubicka [this message]
2012-11-14 19:43 ` hubicka at ucw dot cz
2012-11-14 20:11 ` hubicka at gcc dot gnu.org
2012-11-15 10:28 ` hubicka at gcc dot gnu.org
2012-11-15 10:52 ` hubicka at gcc dot gnu.org
2012-11-15 15:07 ` dominiq at lps dot ens.fr
2012-11-16 10:37 ` hubicka at gcc dot gnu.org
2012-12-06 16:51 ` rguenth at gcc dot gnu.org
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