From: Rico Amslinger <rico.amslinger@informatik.uni-augsburg.de>
Date: Thu, 24 Aug 2017 13:07:44 +0000 (+0200)
Subject: cpu: Fix bi-mode branch predictor thresholds
X-Git-Tag: v19.0.0.0~2639
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=725b19a8154fa557ab3057f07d7cd3c6d798789d;p=gem5.git

cpu: Fix bi-mode branch predictor thresholds

When different sizes were set for the choice and global saturation
counter (e.g. ex5_big), the threshold calculation used the wrong
size. Thus the branch predictor always predicted "not taken" for
choice > global.

Change-Id: I076549ff1482e2280cef24a0d16b7bb2122d4110
Reviewed-on: https://gem5-review.googlesource.com/4560
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
---

diff --git a/src/cpu/pred/bi_mode.cc b/src/cpu/pred/bi_mode.cc
index 69af4584a..e8fda7387 100644
--- a/src/cpu/pred/bi_mode.cc
+++ b/src/cpu/pred/bi_mode.cc
@@ -68,8 +68,8 @@ BiModeBP::BiModeBP(const BiModeBPParams *params)
     globalHistoryMask = globalPredictorSize - 1;
 
     choiceThreshold = (ULL(1) << (choiceCtrBits - 1)) - 1;
-    takenThreshold = (ULL(1) << (choiceCtrBits - 1)) - 1;
-    notTakenThreshold = (ULL(1) << (choiceCtrBits - 1)) - 1;
+    takenThreshold = (ULL(1) << (globalCtrBits - 1)) - 1;
+    notTakenThreshold = (ULL(1) << (globalCtrBits - 1)) - 1;
 }
 
 /*