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From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/62173] [5.0 regression] 64bit Arch can't ivopt while 32bit Arch can Date: Mon, 26 Jan 2015 14:53:00 -0000 [thread overview] Message-ID: <bug-62173-4-63CyYovANR@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-62173-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62173 --- Comment #22 from rguenther at suse dot de <rguenther at suse dot de> --- On Mon, 26 Jan 2015, amker at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62173 > > --- Comment #20 from amker at gcc dot gnu.org --- > (In reply to Richard Biener from comment #18) > > It's probably not correct to simply transfer range info from *idx to > > iv->base. > > Instead SCEV analysis needs to track the range of CHREC_LEFT when it analyzes > > the SSA use-def chain. That's of course a much bigger change :/ > > > > The patch may still help in some cases - I suppose the original testcase is > > reduced from sth else? > > I see it's a tricky problem, and I have to admit that I don't understand it > very well yet. The question is, is relax of POINTER_PLUS_EXPR constraint the > right way fixing this? I do remember some other PRs (other than this one or > bug 52563) are caused by this constraint according to your comments. Well, it's not sure that relaxing POINTER_PLUS_EXPR will help in the end... > Of course, take range information into consideration is always an improvement. > Actually I have another possible example in iv elimination. Curently GCC > simply rejects elimination of an iv use with a candidate if the cand is of > smaller type, but as long as we can prove value of iv use can be represented by > the smaller candidate, elimination is actually safe. But seems to me, fixing > this issue with value information is like a side-effect? Might be - but it's a matter of fixing the observable regression ;)
next prev parent reply other threads:[~2015-01-26 14:53 UTC|newest] Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-08-18 16:12 [Bug target/62173] New: [AArch64] Performance regression due to r213488 spop at gcc dot gnu.org 2014-08-18 16:39 ` [Bug target/62173] " pinskia at gcc dot gnu.org 2014-08-18 19:13 ` spop at gcc dot gnu.org 2014-08-19 1:37 ` amker at gcc dot gnu.org 2014-10-28 11:28 ` [Bug target/62173] [5.0 regression] " jiwang at gcc dot gnu.org 2014-11-14 9:37 ` jiwang at gcc dot gnu.org 2014-11-17 2:14 ` amker.cheng at gmail dot com 2014-11-24 12:15 ` jiwang at gcc dot gnu.org 2014-11-24 12:38 ` jiwang at gcc dot gnu.org 2014-11-24 13:06 ` rguenth at gcc dot gnu.org 2014-11-24 23:01 ` jiwang at gcc dot gnu.org 2014-11-26 10:54 ` [Bug target/62173] [5.0 regression] [AArch64] Can't ivopt array base address while ARM can jiwang at gcc dot gnu.org 2014-11-27 9:35 ` jiwang at gcc dot gnu.org 2014-11-27 12:00 ` [Bug tree-optimization/62173] [5.0 regression] 64bit Arch can't ivopt while 32bit Arch can rguenther at suse dot de 2014-11-27 12:16 ` rguenther at suse dot de 2014-11-27 13:34 ` jiwang at gcc dot gnu.org 2015-01-23 17:33 ` jiwang at gcc dot gnu.org 2015-01-26 10:30 ` rguenth at gcc dot gnu.org 2015-01-26 11:10 ` rguenth at gcc dot gnu.org 2015-01-26 13:48 ` ramana at gcc dot gnu.org 2015-01-26 14:19 ` amker at gcc dot gnu.org 2015-01-26 14:51 ` rguenther at suse dot de 2015-01-26 14:53 ` rguenther at suse dot de [this message] 2015-01-26 15:03 ` amker at gcc dot gnu.org 2015-01-26 15:38 ` jiwang at gcc dot gnu.org 2015-01-27 3:21 ` amker at gcc dot gnu.org 2015-01-27 7:56 ` amker at gcc dot gnu.org 2015-01-27 9:11 ` rguenther at suse dot de 2015-01-28 18:26 ` LpSolit at netscape dot net 2015-01-29 6:48 ` amker at gcc dot gnu.org 2015-01-30 6:42 ` amker at gcc dot gnu.org 2015-01-30 12:32 ` rguenth at gcc dot gnu.org 2015-02-05 7:27 ` amker at gcc dot gnu.org 2015-03-11 17:30 ` [Bug tree-optimization/62173] [5 Regression] " jiwang at gcc dot gnu.org 2015-03-11 17:46 ` jiwang at gcc dot gnu.org 2015-03-11 17:52 ` [Bug tree-optimization/62173] [5/6 " jakub at gcc dot gnu.org 2015-03-13 8:34 ` amker at gcc dot gnu.org 2015-06-02 3:34 ` amker at gcc dot gnu.org 2015-06-03 3:56 ` amker at gcc dot gnu.org 2015-07-22 11:44 ` jiwang at gcc dot gnu.org
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