derek/gem5
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

o3: Fix a couple of issues with the local predictor.

Browse Source 
Fix some issues with the local predictor and the way it's indexed.
This commit is contained in:
Mrinmoy Ghosh
2012-11-02 11:32:00 -05:00
parent 7e25052fee
commit 4440332bdd
1 changed files with 15 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
src/cpu/pred/tournament.cc
View File

@@ -167,7 +167,7 @@ TournamentBP::BTBUpdate(Addr &branch_addr, void * &bp_history)
globalHistory = globalHistory & (globalHistoryMask - 1);
//Update Local History to Not Taken
localHistoryTable[local_history_idx] =
localHistoryTable[local_history_idx] & (localPredictorMask - 1);
localHistoryTable[local_history_idx] & (localPredictorMask & ~ULL(1));
}
bool
@@ -263,8 +263,14 @@ TournamentBP::update(Addr &branch_addr, bool taken, void *bp_history,
// Update may also be called if the Branch target is incorrect even if
// the prediction is correct. In that case do not update the counters.
bool historyPred = false;
unsigned old_local_pred_index = history->localHistory
& localPredictorMask;
unsigned old_local_pred_index = history->localHistory &
localPredictorMask;
bool old_local_pred_valid = history->localHistory !=
invalidPredictorIndex;
assert(old_local_pred_index < localPredictorSize);
if (history->globalUsed) {
historyPred = history->globalPredTaken;
} else {
@@ -291,12 +297,12 @@ TournamentBP::update(Addr &branch_addr, bool taken, void *bp_history,
// need to be updated.
if (taken) {
globalCtrs[history->globalHistory].increment();
if (old_local_pred_index != invalidPredictorIndex) {
if (old_local_pred_valid) {
localCtrs[old_local_pred_index].increment();
}
} else {
globalCtrs[history->globalHistory].decrement();
if (old_local_pred_index != invalidPredictorIndex) {
if (old_local_pred_valid) {
localCtrs[old_local_pred_index].decrement();
}
}
@@ -305,15 +311,15 @@ TournamentBP::update(Addr &branch_addr, bool taken, void *bp_history,
if (taken) {
globalHistory = (history->globalHistory << 1) | 1;
globalHistory = globalHistory & globalHistoryMask;
if (old_local_pred_index != invalidPredictorIndex) {
localHistoryTable[old_local_pred_index] =
if (old_local_pred_valid) {
localHistoryTable[local_history_idx] =
(history->localHistory << 1) | 1;
}
} else {
globalHistory = (history->globalHistory << 1);
globalHistory = globalHistory & globalHistoryMask;
if (old_local_pred_index != invalidPredictorIndex) {
localHistoryTable[old_local_pred_index] =
if (old_local_pred_valid) {
localHistoryTable[local_history_idx] =
history->localHistory << 1;
}
}