Hi,
This patch adjusts the single target indirect call promotion heuristics.
(1) it uses bb counts (bb_all), instead of count "all" which only counts
the targets with the same modules as the caller.
(becaue __gcov_indirect_call_callee is file scope statics).
Using overall bb counts makes more sense here.
(2) use a prameter option to control the threshold.
(3) change the default threshold from 75% to 67%.
Tested with google internal benchmarks and gcc regression test.
Thanks,
-Rong
2013-01-04 Rong Xu <x...@google.com>
* gcc/value-prof.c (gimple_ic_transform_single_targ):
adjust the single_target i_call promotion heuristics.
* gcc/params.def.h: Add new parameter options.
Index: gcc/value-prof.c
===================================================================
--- gcc/value-prof.c (revision 194916)
+++ gcc/value-prof.c (working copy)
@@ -1491,16 +1491,20 @@ gimple_ic_transform_single_targ (gimple stmt, hist
gcov_type prob;
gimple modify;
struct cgraph_node *direct_call;
+ int perc_threshold, count_threshold;
val = histogram->hvalue.counters [0];
count = histogram->hvalue.counters [1];
all = histogram->hvalue.counters [2];
gimple_remove_histogram_value (cfun, stmt, histogram);
+ bb_all = gimple_bb (stmt)->count;
- if (4 * count <= 3 * all)
+ perc_threshold = PARAM_VALUE (PARAM_SINGLE_ICALL_PROMOTE_PERCENT_THRESHOLD);
+ count_threshold = PARAM_VALUE (PARAM_SINGLE_ICALL_PROMOTE_COUNT_THRESHOLD);
+
+ if (100 * count < bb_all * perc_threshold || count < count_threshold)
return false;
- bb_all = gimple_bb (stmt)->count;
/* The order of CHECK_COUNTER calls is important -
since check_counter can correct the third parameter
and we want to make count <= all <= bb_all. */
@@ -1508,6 +1512,7 @@ gimple_ic_transform_single_targ (gimple stmt, hist
|| check_counter (stmt, "ic", &count, &all, all))
return false;
+ all = bb_all;
if (all > 0)
prob = (count * REG_BR_PROB_BASE + all / 2) / all;
else
Index: gcc/params.def
===================================================================
--- gcc/params.def (revision 194916)
+++ gcc/params.def (working copy)
@@ -907,6 +907,7 @@ DEFPARAM (PARAM_LOOP_INVARIANT_MAX_BBS_IN_LOOP,
/* Promote indirect call to conditional direct call only
when the percentage of the target count over the total
indirect call count is no smaller than the threshold. */
+/* For multi-targ indirect_call. */
DEFPARAM (PARAM_ICALL_PROMOTE_PERCENT_THRESHOLD,
"icall-promote-target-percent-threshold",
"percentage threshold for direct call promotion"
@@ -919,6 +920,19 @@ DEFPARAM (PARAM_ICALL_PROMOTE_COUNT_THRESHOLD,
" of a callee target",
1, 0, 0)
+/* For single-targ indirect_call. */
+DEFPARAM (PARAM_SINGLE_ICALL_PROMOTE_PERCENT_THRESHOLD,
+ "single_icall-promote-target-percent-threshold",
+ "percentage threshold for direct call promotion"
+ " of a callee target",
+ 67, 0, 100)
+
+DEFPARAM (PARAM_SINGLE_ICALL_PROMOTE_COUNT_THRESHOLD,
+ "single_icall-promote-target_count-threshold",
+ "call count threshold for direct call promotion"
+ " of a callee target",
+ 1, 0, 0)
+
/* 0: do not always inline icall target:
other value: always inline icall target when call count
exceeds this value.
--
This patch is available for review at http://codereview.appspot.com/7059044
