[Bug tree-optimization/50204] [4.5/4.6/4.7 Regression] Missed fully redundant load found in crafty (SPEC 2k)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 --- Comment #10 from Richard Guenther 2011-10-11 11:57:28 UTC --- Author: rguenth Date: Tue Oct 11 11:57:23 2011 New Revision: 179799 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=179799 Log: 2011-10-11 Richard Guenther PR tree-optimization/50204 * tree-ssa-alias.c (get_continuation_for_phi_1): Split out two argument handling from ... (get_continuation_for_phi): ... here. Handle arbitrary number of PHI args. * gcc.dg/tree-ssa/ssa-fre-36.c: New testcase. Added: trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-36.c Modified: trunk/gcc/ChangeLog trunk/gcc/testsuite/ChangeLog trunk/gcc/tree-ssa-alias.c
[Bug tree-optimization/50204] [4.5/4.6/4.7 Regression] Missed fully redundant load found in crafty (SPEC 2k)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 Richard Guenther changed: What|Removed |Added Status|NEW |ASSIGNED AssignedTo|unassigned at gcc dot |rguenth at gcc dot gnu.org |gnu.org | --- Comment #9 from Richard Guenther 2011-10-11 09:01:47 UTC --- Mine.
[Bug tree-optimization/50204] [4.5/4.6/4.7 Regression] Missed fully redundant load found in crafty (SPEC 2k)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 --- Comment #8 from Andrew Pinski 2011-10-10 20:51:11 UTC --- (In reply to comment #7) > Do you mind if I take over the patch? No I don't mind at all.
[Bug tree-optimization/50204] [4.5/4.6/4.7 Regression] Missed fully redundant load found in crafty (SPEC 2k)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 --- Comment #7 from rguenther at suse dot de 2011-10-10 20:48:40 UTC --- On Mon, 10 Oct 2011, pinskia at gcc dot gnu.org wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 > > --- Comment #6 from Andrew Pinski 2011-10-10 > 19:58:32 UTC --- > (In reply to comment #5) > > Ping? It would be nice to have this patch in 4.7 ... > > I cannot officially submit it until Cavium's assignment has been fully > submitted. Do you mind if I take over the patch?
[Bug tree-optimization/50204] [4.5/4.6/4.7 Regression] Missed fully redundant load found in crafty (SPEC 2k)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 --- Comment #6 from Andrew Pinski 2011-10-10 19:58:32 UTC --- (In reply to comment #5) > Ping? It would be nice to have this patch in 4.7 ... I cannot officially submit it until Cavium's assignment has been fully submitted.
[Bug tree-optimization/50204] [4.5/4.6/4.7 Regression] Missed fully redundant load found in crafty (SPEC 2k)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 --- Comment #5 from Richard Guenther 2011-10-10 12:28:19 UTC --- Ping? It would be nice to have this patch in 4.7 ...
[Bug tree-optimization/50204] [4.5/4.6/4.7 Regression] Missed fully redundant load found in crafty (SPEC 2k)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 --- Comment #4 from Richard Guenther 2011-08-29 07:57:29 UTC --- On a 2nd thought the work should be still linear, even for N PHI args the way the merging is constructed (one arg has to dominate the other - the only exception is the diamond case which has a constant cost of two). So with some cleanup (essentially peel the first iteration of the loop) the patch should be ok as-is.
[Bug tree-optimization/50204] [4.5/4.6/4.7 Regression] Missed fully redundant load found in crafty (SPEC 2k)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 --- Comment #3 from Richard Guenther 2011-08-29 07:29:57 UTC --- The loop over PHI args is a little hard to follow, but yeah, that's how it should work. Eventually we can put this in with a new --param telling the maximum number of PHI args to consider (and defaulting it to two). I'd probably keep the n == 1 handling in the main function separately instead of trying to handle it via the loop. Then I'd pre-seed the first arg which should make the loop a little easier to follow.
[Bug tree-optimization/50204] [4.5/4.6/4.7 Regression] Missed fully redundant load found in crafty (SPEC 2k)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 --- Comment #2 from Andrew Pinski 2011-08-29 03:00:48 UTC --- Created attachment 25124 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25124 Patch which was tested on x86_64 without any regressions Note I am going to add this patch here as the copyright assignment for Cavium is not completed yet (though it is in the process of clearing up). This implements what is mentioned in comment #1 and was tested on x86_64-linux-gnu with no regressions. I don't know what the compile time slow down that happens yet and have not added any testcases but it works on the testcase attached to the bug. I also have not checked what the performance increase on SPEC would be.
[Bug tree-optimization/50204] [4.5/4.6/4.7 Regression] Missed fully redundant load found in crafty (SPEC 2k)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 Richard Guenther changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2011-08-27 CC||rguenth at gcc dot gnu.org Ever Confirmed|0 |1 --- Comment #1 from Richard Guenther 2011-08-27 08:13:12 UTC --- This is because we have, for the 2nd load : # .MEM_4 = PHI <.MEM_7(3), .MEM_6(D)(4), .MEM_8(5)> # VUSE <.MEM_4> opening.0_3 = opening; if (opening.0_3 != 4) Thus three incoming edges. The walker in SCCVN does not try to handle more than two, see tree-ssa-alias.c:get_continuation_for_phi (). In principle one can handle N PHI arguments by reducing them to N - 1 PHI arguments by handling two of them and reducing them to the dominating continuation. And then iterate. But the idea of get_continuation_for_phi () is to make this walk linear which it wouldn't be for this case. Confirmed anyway. I suppose it's not performance critical for crafty to see this redundant load?
[Bug tree-optimization/50204] [4.5/4.6/4.7 Regression] Missed fully redundant load found in crafty (SPEC 2k)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50204 Andrew Pinski changed: What|Removed |Added Keywords||missed-optimization Known to work||4.3.3 Target Milestone|--- |4.5.4 Known to fail||4.5.4, 4.6.1, 4.7.0
