This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Fix direction of polymorphic call predictor
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: gcc-patches at gcc dot gnu dot org
- Date: Fri, 6 Jan 2017 17:11:51 +0100
- Subject: Fix direction of polymorphic call predictor
- Authentication-results: sourceware.org; auth=none
Hi,
this is next patch to tweak call predictors. It fixes bug in the direction of
predictor (like normal calls, polymorphic calls are usually not taken when
there is if guariding them) and feeds in correct data from Martin's table.
Bootstrapped/regtested x86_64-linux, comitted.
I will fix the indirect call predictor next after periodic testers pick up the
change.
Honza
Index: ChangeLog
===================================================================
--- ChangeLog (revision 244166)
+++ ChangeLog (working copy)
@@ -1,3 +1,10 @@
+2017-01-01 Jan Hubicka <hubicka@ucw.cz>
+
+ PR middle-end/77484
+ * predict.def (PRED_POLYMORPHIC_CALL): Set to 58
+ * predict.c (tree_estimate_probability_bb): Reverse direction of
+ polymorphic call predictor.
+
2017-01-06 David Malcolm <dmalcolm@redhat.com>
* passes.c (execute_one_pass): Split out pass-skipping logic
Index: predict.c
===================================================================
--- predict.c (revision 244166)
+++ predict.c (working copy)
@@ -2789,7 +2789,7 @@ tree_estimate_probability_bb (basic_bloc
if (gimple_call_fndecl (stmt))
predict_edge_def (e, PRED_CALL, NOT_TAKEN);
else if (virtual_method_call_p (gimple_call_fn (stmt)))
- predict_edge_def (e, PRED_POLYMORPHIC_CALL, TAKEN);
+ predict_edge_def (e, PRED_POLYMORPHIC_CALL, NOT_TAKEN);
else
predict_edge_def (e, PRED_INDIR_CALL, TAKEN);
break;
Index: predict.def
===================================================================
--- predict.def (revision 244166)
+++ predict.def (working copy)
@@ -122,7 +122,7 @@ DEF_PREDICTOR (PRED_CALL, "call", HITRAT
less reliable for indirect calls and polymorphic calls. For spec2k6
the predictio nis slightly in the direction of taking the call. */
DEF_PREDICTOR (PRED_INDIR_CALL, "indirect call", HITRATE (51), 0)
-DEF_PREDICTOR (PRED_POLYMORPHIC_CALL, "polymorphic call", HITRATE (58), 0)
+DEF_PREDICTOR (PRED_POLYMORPHIC_CALL, "polymorphic call", HITRATE (59), 0)
/* Recursive calls are usually not taken or the function will recurse
indefinitely. */