Third part changes predictors values:
1) PRED_LOOP_EXIT: no dominant branch; value simply taken from statistics
2) PRED_LOOP_EXIT_WITH_RECURSION: there are 4 dominant edges; value taken w/o
these edges
3) PRED_LOOP_EXTRA_EXIT: there's one really dominant edge; value taken w/o the
edge; note that
coverage of the predictor is quite small
4) PRED_OPCODE_POSITIVE: no dominant branch; value simply taken from statistics
5) PRED_CONST_RETURN: there are 4 dominant edges, value taken w/o these edges
6) PRED_NULL_RETURN: one dominant edge, value taken w/o these edges
7) PRED_LOOP_IV_COMPARE_GUESS: very fragile predictor (according how is
identified in predict.c);
has a dominant edge; value taken w/o these edges; in future I plan to
investigate it
8) PRED_LOOP_GUARD: adjusted based on numbers without a one dominant edge
Martin
>From 960f16a6e3e916524d8881f53913c15a3c2ec2ae Mon Sep 17 00:00:00 2001
From: marxin <mli...@suse.cz>
Date: Thu, 28 Dec 2017 10:13:50 +0100
Subject: [PATCH 3/5] Adjust predictor values according to SPEC2006 and
SPEC2017.
gcc/ChangeLog:
2017-12-28 Martin Liska <mli...@suse.cz>
* predict.def (PRED_LOOP_EXIT): Change from 85 to 89.
(PRED_LOOP_EXIT_WITH_RECURSION): Change from 72 to 78.
(PRED_LOOP_EXTRA_EXIT): Change from 83 to 67.
(PRED_OPCODE_POSITIVE): Change from 64 to 59.
(PRED_TREE_OPCODE_POSITIVE): Change from 64 to 59.
(PRED_CONST_RETURN): Change from 69 to 65.
(PRED_NULL_RETURN): Change from 91 to 71.
(PRED_LOOP_IV_COMPARE_GUESS): Change from 98 to 64.
(PRED_LOOP_GUARD): Change from 66 to 73.
---
gcc/predict.def | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/gcc/predict.def b/gcc/predict.def
index 390b9a35fa7..fe72080d5bd 100644
--- a/gcc/predict.def
+++ b/gcc/predict.def
@@ -89,16 +89,16 @@ DEF_PREDICTOR (PRED_COLD_FUNCTION, "cold function call", PROB_VERY_LIKELY,
PRED_FLAG_FIRST_MATCH)
/* Edge causing loop to terminate is probably not taken. */
-DEF_PREDICTOR (PRED_LOOP_EXIT, "loop exit", HITRATE (85),
+DEF_PREDICTOR (PRED_LOOP_EXIT, "loop exit", HITRATE (89),
PRED_FLAG_FIRST_MATCH)
/* Same as LOOP_EXIT but for loops containing recursive call. */
DEF_PREDICTOR (PRED_LOOP_EXIT_WITH_RECURSION, "loop exit with recursion",
- HITRATE (72), PRED_FLAG_FIRST_MATCH)
+ HITRATE (78), PRED_FLAG_FIRST_MATCH)
/* Edge causing loop to terminate by computing value used by later
conditional. */
-DEF_PREDICTOR (PRED_LOOP_EXTRA_EXIT, "extra loop exit", HITRATE (83),
+DEF_PREDICTOR (PRED_LOOP_EXTRA_EXIT, "extra loop exit", HITRATE (67),
PRED_FLAG_FIRST_MATCH)
/* Pointers are usually not NULL. */
@@ -106,11 +106,11 @@ DEF_PREDICTOR (PRED_POINTER, "pointer", HITRATE (70), 0)
DEF_PREDICTOR (PRED_TREE_POINTER, "pointer (on trees)", HITRATE (70), 0)
/* NE is probable, EQ not etc... */
-DEF_PREDICTOR (PRED_OPCODE_POSITIVE, "opcode values positive", HITRATE (64), 0)
+DEF_PREDICTOR (PRED_OPCODE_POSITIVE, "opcode values positive", HITRATE (59), 0)
DEF_PREDICTOR (PRED_OPCODE_NONEQUAL, "opcode values nonequal", HITRATE (66), 0)
DEF_PREDICTOR (PRED_FPOPCODE, "fp_opcode", HITRATE (90), 0)
DEF_PREDICTOR (PRED_TREE_OPCODE_POSITIVE, "opcode values positive (on trees)",
- HITRATE (64), 0)
+ HITRATE (59), 0)
DEF_PREDICTOR (PRED_TREE_OPCODE_NONEQUAL, "opcode values nonequal (on trees)",
HITRATE (66), 0)
DEF_PREDICTOR (PRED_TREE_FPOPCODE, "fp_opcode (on trees)", HITRATE (90), 0)
@@ -136,18 +136,18 @@ DEF_PREDICTOR (PRED_TREE_EARLY_RETURN, "early return (on trees)", HITRATE (66),
DEF_PREDICTOR (PRED_GOTO, "goto", HITRATE (66), 0)
/* Branch ending with return constant is probably not taken. */
-DEF_PREDICTOR (PRED_CONST_RETURN, "const return", HITRATE (69), 0)
+DEF_PREDICTOR (PRED_CONST_RETURN, "const return", HITRATE (65), 0)
/* Branch ending with return negative constant is probably not taken. */
DEF_PREDICTOR (PRED_NEGATIVE_RETURN, "negative return", HITRATE (98), 0)
/* Branch ending with return; is probably not taken */
-DEF_PREDICTOR (PRED_NULL_RETURN, "null return", HITRATE (91), 0)
+DEF_PREDICTOR (PRED_NULL_RETURN, "null return", HITRATE (71), 0)
/* Branches to compare induction variable to a loop bound is
extremely likely. */
DEF_PREDICTOR (PRED_LOOP_IV_COMPARE_GUESS, "guess loop iv compare",
- HITRATE (98), 0)
+ HITRATE (64), 0)
/* Use number of loop iterations determined by # of iterations analysis
to set probability of branches that compares IV to loop bound variable. */
@@ -160,7 +160,7 @@ DEF_PREDICTOR (PRED_LOOP_IV_COMPARE, "loop iv compare", PROB_UNINITIALIZED,
for (loop2)
body;
guess that cond is unlikely. */
-DEF_PREDICTOR (PRED_LOOP_GUARD, "loop guard", HITRATE (66), 0)
+DEF_PREDICTOR (PRED_LOOP_GUARD, "loop guard", HITRATE (73), 0)
/* Same but for loops containing recursion. */
DEF_PREDICTOR (PRED_LOOP_GUARD_WITH_RECURSION, "loop guard with recursion",
--
2.14.3
