From 813d6db9c42ae27854356c87f0fa16b0f9079118 Mon Sep 17 00:00:00 2001 From: Martin Liska Date: Tue, 23 Jan 2018 16:43:59 +0100 Subject: [PATCH] Remove predictors that are unrealiable. 2018-01-23 Martin Liska * predict.def (PRED_INDIR_CALL): Set probability to PROB_EVEN in order to ignore the predictor. (PRED_POLYMORPHIC_CALL): Likewise. (PRED_RECURSIVE_CALL): Likewise. From-SVN: r256988 --- gcc/ChangeLog | 7 +++++++ gcc/predict.c | 2 +- gcc/predict.def | 14 +++++--------- 3 files changed, 13 insertions(+), 10 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index fd93bc8a426..3238e70f63e 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2018-01-23 Martin Liska + + * predict.def (PRED_INDIR_CALL): Set probability to PROB_EVEN in + order to ignore the predictor. + (PRED_POLYMORPHIC_CALL): Likewise. + (PRED_RECURSIVE_CALL): Likewise. + 2018-01-23 Martin Liska * tree-profile.c (tree_profiling): Print function header to diff --git a/gcc/predict.c b/gcc/predict.c index 724ba458db9..2d932e9fd11 100644 --- a/gcc/predict.c +++ b/gcc/predict.c @@ -4216,7 +4216,7 @@ test_prediction_value_range () continue; unsigned p = 100 * predictors[i].probability / REG_BR_PROB_BASE; - ASSERT_TRUE (p > 50 && p <= 100); + ASSERT_TRUE (p >= 50 && p <= 100); } } diff --git a/gcc/predict.def b/gcc/predict.def index fe72080d5bd..4ed97ed165c 100644 --- a/gcc/predict.def +++ b/gcc/predict.def @@ -118,15 +118,11 @@ DEF_PREDICTOR (PRED_TREE_FPOPCODE, "fp_opcode (on trees)", HITRATE (90), 0) /* Branch guarding call is probably taken. */ DEF_PREDICTOR (PRED_CALL, "call", HITRATE (67), 0) -/* PRED_CALL is not very reliable predictor and it turns out to be even - 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 (86), 0) -DEF_PREDICTOR (PRED_POLYMORPHIC_CALL, "polymorphic call", HITRATE (59), 0) - -/* Recursive calls are usually not taken or the function will recurse - indefinitely. */ -DEF_PREDICTOR (PRED_RECURSIVE_CALL, "recursive call", HITRATE (75), 0) +/* Call predictors are for now ignored, lets leave the predictor + to measure its benefit. */ +DEF_PREDICTOR (PRED_INDIR_CALL, "indirect call", PROB_EVEN, 0) +DEF_PREDICTOR (PRED_POLYMORPHIC_CALL, "polymorphic call", PROB_EVEN, 0) +DEF_PREDICTOR (PRED_RECURSIVE_CALL, "recursive call", PROB_EVEN, 0) /* Branch causing function to terminate is probably not taken. */ DEF_PREDICTOR (PRED_TREE_EARLY_RETURN, "early return (on trees)", HITRATE (66), -- 2.30.2