Rico Amslinger has submitted this change and it was merged. (
https://gem5-review.googlesource.com/4560 )
Change subject: cpu: Fix bi-mode branch predictor thresholds
......................................................................
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 <[email protected]>
Maintainer: Jason Lowe-Power <[email protected]>
---
M src/cpu/pred/bi_mode.cc
1 file changed, 2 insertions(+), 2 deletions(-)
Approvals:
Curtis Dunham: Looks good to me, approved
Jason Lowe-Power: Looks good to me, approved
diff --git a/src/cpu/pred/bi_mode.cc b/src/cpu/pred/bi_mode.cc
index 69af458..e8fda73 100644
--- a/src/cpu/pred/bi_mode.cc
+++ b/src/cpu/pred/bi_mode.cc
@@ -68,8 +68,8 @@
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;
}
/*
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-MessageType: merged
Gerrit-Change-Id: I076549ff1482e2280cef24a0d16b7bb2122d4110
Gerrit-Change-Number: 4560
Gerrit-PatchSet: 2
Gerrit-Owner: Rico Amslinger <[email protected]>
Gerrit-Assignee: Curtis Dunham <[email protected]>
Gerrit-Reviewer: Curtis Dunham <[email protected]>
Gerrit-Reviewer: Jason Lowe-Power <[email protected]>
Gerrit-Reviewer: Rico Amslinger <[email protected]>
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