[Bug target/41279] New: [4.5 Regression] 252.eon performance regression

[Bug target/41279] New: [4.5 Regression] 252.eon performance regression

[rguenth at gcc dot gnu dot org]

Happened between revs 151305 (good) and 151347 (bad).  This range includes
the VTA merge and the SRA useless transformation fix.


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           Summary: [4.5 Regression] 252.eon performance regression
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rguenth at gcc dot gnu dot org
GCC target triplet: ia64-*-*


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2009-09-05 16:07 -------
Likewise effects in SPEC FP.  My guess would be scheduler effects of the VTA
changes there.  While compare-debug tests code generation is the same with
-g vs. -g0 nothing checks code generation differences caused by the VTA
"fixes".


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[rguenth at gcc dot gnu dot org]

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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2009-09-05 16:14 -------
I'll revert the SRA fix on the tester to rule out that change for tonight.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2009-09-06 10:17 -------
Most of the eon regression was due to the SRA patch.  Other changes weren't
affected by the SRA patch and so have to be attributed to VTA.

See http://gcc.opensuse.org/SPEC/CFP/sb-terbium-head-64/recent.html
and http://gcc.opensuse.org/SPEC/CINT/sb-terbium-head-64/recent.html

and the bumps around Sep 3rd.  I guess VTA wasn't supposed to change code
generation at all.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[jamborm at gcc dot gnu dot org]

------- Comment #4 from jamborm at gcc dot gnu dot org  2009-09-07 12:05 -------
Hm, I wonder how come we did not come across this when testing the
patch for exactly these kinds of problems in July.  Anyway, I will
have a look at it.

Nevertheless, I believe we should split this bug in two so that we can
track the SRA and VTA regressions separately.  So unless someone
objects or I realize the fix is so trivial it does not really deserve
its own PR, I'll create a new Pr for the SRA issue when I come across
something interesting.


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jamborm at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|mjambor at suse dot cz      |jamborm at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[jamborm at gcc dot gnu dot org]

------- Comment #5 from jamborm at gcc dot gnu dot org  2009-09-08 11:58 -------
I tried to reproduce this manually (on thallium:/abuild/mjambor/) but
couldn't.  I just get the same execution times with or without that
patch reverted... I am not sure what this means or how to proceed from
here.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[jakub at gcc dot gnu dot org]

------- Comment #6 from jakub at gcc dot gnu dot org  2009-09-29 21:42 -------
I've looked at what code generation changes the jump from r151310 to r151312
(aka VTA merge) and on eon.cc at -O3 -funroll-loops -fpeel-loops on ia64-linux
the difference is that r151310 unroll something that r151312 does not.
The change that caused this is in num_loop_insns:
@@ -176,8 +176,8 @@ num_loop_insns (const struct loop *loop)
     {
       bb = bbs[i];
       ninsns++;
-      for (insn = BB_HEAD (bb); insn != BB_END (bb); insn = NEXT_INSN (insn))
-       if (INSN_P (insn))
+      FOR_BB_INSNS (bb, insn)
+       if (NONDEBUG_INSN_P (insn))
          ninsns++;
     }
   free(bbs);

Note that before we didn't count BB_END (bb) insn (well, it is probably counted
in that ninsns++ before the loop), but now we do.  Similar change to
average_num_loop_insns changed binsns = 1; before the loop to binsns = 0;, so I
think that:
--- cfgloopanal.c.xx    2009-09-29 17:19:59.000000000 +0200
+++ cfgloopanal.c       2009-09-29 23:30:26.000000000 +0200
@@ -175,12 +175,11 @@ num_loop_insns (const struct loop *loop)
   for (i = 0; i < loop->num_nodes; i++)
     {
       bb = bbs[i];
-      ninsns++;
       FOR_BB_INSNS (bb, insn)
        if (NONDEBUG_INSN_P (insn))
          ninsns++;
     }
-  free(bbs);
+  free (bbs);

   return ninsns;
 }
is a correct change.  No idea whether 252.eon's hot loop is in eon.cc or
elsewhere though.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[jakub at gcc dot gnu dot org]

------- Comment #7 from jakub at gcc dot gnu dot org  2009-09-30 09:58 -------
Subject: Bug 41279

Author: jakub
Date: Wed Sep 30 09:57:56 2009
New Revision: 152324

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=152324
Log:
        PR target/41279
        * cfgloopanal.c (num_loop_insns): Don't increment ninsns for each bb
        before insn counting loop now that BB_END (bb) is counted.  Ensure
        the return value isn't zero.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/cfgloopanal.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[sje at cup dot hp dot com]

------- Comment #8 from sje at cup dot hp dot com  2009-10-30 20:42 -------
It looks like a patch has been checked in to fix this bug, is there any reason
we can't close this defect?


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sje at cup dot hp dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sje at cup dot hp dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[rguenth at gcc dot gnu dot org]

------- Comment #9 from rguenth at gcc dot gnu dot org  2009-10-30 22:10 -------
It didn't have any effect on the regression.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279

[Bug target/41279] [4.5 Regression] 252.eon performance regression

[rguenth at gcc dot gnu dot org]

------- Comment #10 from rguenth at gcc dot gnu dot org  2009-12-16 22:48 -------
Seems to be fixed now.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41279