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

["jakub at gcc dot gnu dot org" <gcc-bugzilla 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.


-- 


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