cpu: Implement per-thread GHRs
Branch predictors that use GHRs should index them on a per-thread basis. This makes that so.
This commit is contained in:
Curtis Dunham
parent
1578d2d0b6
commit
76ee011a12
8 changed files with 110 additions and 108 deletions
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@ -78,7 +78,7 @@ LocalBP::reset()
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}
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void
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LocalBP::btbUpdate(Addr branch_addr, void * &bp_history)
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LocalBP::btbUpdate(ThreadID tid, Addr branch_addr, void * &bp_history)
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{
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// Place holder for a function that is called to update predictor history when
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// a BTB entry is invalid or not found.
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@ -86,7 +86,7 @@ LocalBP::btbUpdate(Addr branch_addr, void * &bp_history)
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bool
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LocalBP::lookup(Addr branch_addr, void * &bp_history)
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LocalBP::lookup(ThreadID tid, Addr branch_addr, void * &bp_history)
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{
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bool taken;
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uint8_t counter_val;
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@ -117,7 +117,8 @@ LocalBP::lookup(Addr branch_addr, void * &bp_history)
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}
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void
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LocalBP::update(Addr branch_addr, bool taken, void *bp_history, bool squashed)
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LocalBP::update(ThreadID tid, Addr branch_addr, bool taken, void *bp_history,
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bool squashed)
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{
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assert(bp_history == NULL);
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unsigned local_predictor_idx;
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@ -152,7 +153,7 @@ LocalBP::getLocalIndex(Addr &branch_addr)
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}
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void
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LocalBP::uncondBranch(Addr pc, void *&bp_history)
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LocalBP::uncondBranch(ThreadID tid, Addr pc, void *&bp_history)
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{
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}
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@ -66,7 +66,7 @@ class LocalBP : public BPredUnit
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*/
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LocalBP(const LocalBPParams *params);
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virtual void uncondBranch(Addr pc, void * &bp_history);
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virtual void uncondBranch(ThreadID tid, Addr pc, void * &bp_history);
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/**
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* Looks up the given address in the branch predictor and returns
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@ -75,7 +75,7 @@ class LocalBP : public BPredUnit
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* @param bp_history Pointer to any bp history state.
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* @return Whether or not the branch is taken.
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*/
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bool lookup(Addr branch_addr, void * &bp_history);
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bool lookup(ThreadID tid, Addr branch_addr, void * &bp_history);
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/**
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* Updates the branch predictor to Not Taken if a BTB entry is
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@ -84,19 +84,20 @@ class LocalBP : public BPredUnit
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* @param bp_history Pointer to any bp history state.
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* @return Whether or not the branch is taken.
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*/
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void btbUpdate(Addr branch_addr, void * &bp_history);
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void btbUpdate(ThreadID tid, Addr branch_addr, void * &bp_history);
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/**
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* Updates the branch predictor with the actual result of a branch.
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* @param branch_addr The address of the branch to update.
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* @param taken Whether or not the branch was taken.
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*/
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void update(Addr branch_addr, bool taken, void *bp_history, bool squashed);
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void update(ThreadID tid, Addr branch_addr, bool taken, void *bp_history,
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bool squashed);
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void retireSquashed(void *bp_history)
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void retireSquashed(ThreadID tid, void *bp_history)
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{ assert(bp_history == NULL); }
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void squash(void *bp_history)
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void squash(ThreadID tid, void *bp_history)
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{ assert(bp_history == NULL); }
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void reset();
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@ -38,7 +38,7 @@
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BiModeBP::BiModeBP(const BiModeBPParams *params)
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: BPredUnit(params),
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globalHistoryReg(0),
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globalHistoryReg(params->numThreads, 0),
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globalHistoryBits(ceilLog2(params->globalPredictorSize)),
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choicePredictorSize(params->choicePredictorSize),
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choiceCtrBits(params->choiceCtrBits),
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@ -77,23 +77,23 @@ BiModeBP::BiModeBP(const BiModeBPParams *params)
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* chooses the taken array and the taken array predicts taken.
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*/
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void
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BiModeBP::uncondBranch(Addr pc, void * &bpHistory)
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BiModeBP::uncondBranch(ThreadID tid, Addr pc, void * &bpHistory)
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{
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BPHistory *history = new BPHistory;
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history->globalHistoryReg = globalHistoryReg;
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history->globalHistoryReg = globalHistoryReg[tid];
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history->takenUsed = true;
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history->takenPred = true;
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history->notTakenPred = true;
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history->finalPred = true;
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bpHistory = static_cast<void*>(history);
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updateGlobalHistReg(true);
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updateGlobalHistReg(tid, true);
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}
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void
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BiModeBP::squash(void *bpHistory)
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BiModeBP::squash(ThreadID tid, void *bpHistory)
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{
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BPHistory *history = static_cast<BPHistory*>(bpHistory);
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globalHistoryReg = history->globalHistoryReg;
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globalHistoryReg[tid] = history->globalHistoryReg;
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delete history;
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}
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@ -108,12 +108,12 @@ BiModeBP::squash(void *bpHistory)
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* direction predictors for the final branch prediction.
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*/
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bool
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BiModeBP::lookup(Addr branchAddr, void * &bpHistory)
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BiModeBP::lookup(ThreadID tid, Addr branchAddr, void * &bpHistory)
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{
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unsigned choiceHistoryIdx = ((branchAddr >> instShiftAmt)
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& choiceHistoryMask);
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unsigned globalHistoryIdx = (((branchAddr >> instShiftAmt)
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^ globalHistoryReg)
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^ globalHistoryReg[tid])
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& globalHistoryMask);
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assert(choiceHistoryIdx < choicePredictorSize);
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@ -128,7 +128,7 @@ BiModeBP::lookup(Addr branchAddr, void * &bpHistory)
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bool finalPrediction;
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BPHistory *history = new BPHistory;
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history->globalHistoryReg = globalHistoryReg;
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history->globalHistoryReg = globalHistoryReg[tid];
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history->takenUsed = choicePrediction;
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history->takenPred = takenGHBPrediction;
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history->notTakenPred = notTakenGHBPrediction;
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@ -141,15 +141,15 @@ BiModeBP::lookup(Addr branchAddr, void * &bpHistory)
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history->finalPred = finalPrediction;
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bpHistory = static_cast<void*>(history);
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updateGlobalHistReg(finalPrediction);
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updateGlobalHistReg(tid, finalPrediction);
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return finalPrediction;
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}
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void
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BiModeBP::btbUpdate(Addr branchAddr, void * &bpHistory)
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BiModeBP::btbUpdate(ThreadID tid, Addr branchAddr, void * &bpHistory)
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{
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globalHistoryReg &= (historyRegisterMask & ~ULL(1));
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globalHistoryReg[tid] &= (historyRegisterMask & ~ULL(1));
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}
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/* Only the selected direction predictor will be updated with the final
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@ -159,7 +159,8 @@ BiModeBP::btbUpdate(Addr branchAddr, void * &bpHistory)
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* the direction predictors makes a correct final prediction.
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*/
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void
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BiModeBP::update(Addr branchAddr, bool taken, void *bpHistory, bool squashed)
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BiModeBP::update(ThreadID tid, Addr branchAddr, bool taken, void *bpHistory,
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bool squashed)
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{
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if (bpHistory) {
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BPHistory *history = static_cast<BPHistory*>(bpHistory);
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@ -218,11 +219,11 @@ BiModeBP::update(Addr branchAddr, bool taken, void *bpHistory, bool squashed)
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if (squashed) {
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if (taken) {
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globalHistoryReg = (history->globalHistoryReg << 1) | 1;
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globalHistoryReg[tid] = (history->globalHistoryReg << 1) | 1;
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} else {
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globalHistoryReg = (history->globalHistoryReg << 1);
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globalHistoryReg[tid] = (history->globalHistoryReg << 1);
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}
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globalHistoryReg &= historyRegisterMask;
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globalHistoryReg[tid] &= historyRegisterMask;
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} else {
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delete history;
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}
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@ -230,24 +231,24 @@ BiModeBP::update(Addr branchAddr, bool taken, void *bpHistory, bool squashed)
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}
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void
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BiModeBP::retireSquashed(void *bp_history)
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BiModeBP::retireSquashed(ThreadID tid, void *bp_history)
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{
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BPHistory *history = static_cast<BPHistory*>(bp_history);
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delete history;
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}
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unsigned
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BiModeBP::getGHR(void *bp_history) const
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BiModeBP::getGHR(ThreadID tid, void *bp_history) const
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{
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return static_cast<BPHistory*>(bp_history)->globalHistoryReg;
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}
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void
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BiModeBP::updateGlobalHistReg(bool taken)
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BiModeBP::updateGlobalHistReg(ThreadID tid, bool taken)
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{
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globalHistoryReg = taken ? (globalHistoryReg << 1) | 1 :
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(globalHistoryReg << 1);
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globalHistoryReg &= historyRegisterMask;
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globalHistoryReg[tid] = taken ? (globalHistoryReg[tid] << 1) | 1 :
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(globalHistoryReg[tid] << 1);
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globalHistoryReg[tid] &= historyRegisterMask;
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}
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BiModeBP*
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@ -57,16 +57,17 @@ class BiModeBP : public BPredUnit
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{
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public:
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BiModeBP(const BiModeBPParams *params);
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void uncondBranch(Addr pc, void * &bp_history);
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void squash(void *bp_history);
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bool lookup(Addr branch_addr, void * &bp_history);
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void btbUpdate(Addr branch_addr, void * &bp_history);
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void update(Addr branch_addr, bool taken, void *bp_history, bool squashed);
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void retireSquashed(void *bp_history);
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unsigned getGHR(void *bp_history) const;
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void uncondBranch(ThreadID tid, Addr pc, void * &bp_history);
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void squash(ThreadID tid, void *bp_history);
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bool lookup(ThreadID tid, Addr branch_addr, void * &bp_history);
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void btbUpdate(ThreadID tid, Addr branch_addr, void * &bp_history);
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void update(ThreadID tid, Addr branch_addr, bool taken, void *bp_history,
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bool squashed);
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void retireSquashed(ThreadID tid, void *bp_history);
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unsigned getGHR(ThreadID tid, void *bp_history) const;
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private:
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void updateGlobalHistReg(bool taken);
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void updateGlobalHistReg(ThreadID tid, bool taken);
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struct BPHistory {
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unsigned globalHistoryReg;
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@ -95,7 +96,7 @@ class BiModeBP : public BPredUnit
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// not-taken direction predictors
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std::vector<SatCounter> notTakenCounters;
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unsigned globalHistoryReg;
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std::vector<unsigned> globalHistoryReg;
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unsigned globalHistoryBits;
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unsigned historyRegisterMask;
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@ -195,10 +195,10 @@ BPredUnit::predict(const StaticInstPtr &inst, const InstSeqNum &seqNum,
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DPRINTF(Branch, "[tid:%i]: Unconditional control.\n", tid);
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pred_taken = true;
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// Tell the BP there was an unconditional branch.
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uncondBranch(pc.instAddr(), bp_history);
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uncondBranch(tid, pc.instAddr(), bp_history);
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} else {
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++condPredicted;
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pred_taken = lookup(pc.instAddr(), bp_history);
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pred_taken = lookup(tid, pc.instAddr(), bp_history);
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DPRINTF(Branch, "[tid:%i]: [sn:%i] Branch predictor"
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" predicted %i for PC %s\n", tid, seqNum, pred_taken, pc);
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@ -265,7 +265,7 @@ BPredUnit::predict(const StaticInstPtr &inst, const InstSeqNum &seqNum,
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// because the BTB did not have an entry
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// The predictor needs to be updated accordingly
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if (!inst->isCall() && !inst->isReturn()) {
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btbUpdate(pc.instAddr(), bp_history);
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btbUpdate(tid, pc.instAddr(), bp_history);
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DPRINTF(Branch, "[tid:%i]:[sn:%i] btbUpdate"
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" called for %s\n", tid, seqNum, pc);
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} else if (inst->isCall() && !inst->isUncondCtrl()) {
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@ -278,8 +278,8 @@ BPredUnit::predict(const StaticInstPtr &inst, const InstSeqNum &seqNum,
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predict_record.wasIndirect = true;
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++indirectLookups;
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//Consult indirect predictor on indirect control
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if (iPred.lookup(pc.instAddr(), getGHR(bp_history), target,
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tid)) {
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if (iPred.lookup(pc.instAddr(), getGHR(tid, bp_history),
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target, tid)) {
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// Indirect predictor hit
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++indirectHits;
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DPRINTF(Branch, "[tid:%i]: Instruction %s predicted "
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@ -346,7 +346,7 @@ BPredUnit::predictInOrder(const StaticInstPtr &inst, const InstSeqNum &seqNum,
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DPRINTF(Branch, "[tid:%i] Unconditional control.\n", tid);
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pred_taken = true;
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// Tell the BP there was an unconditional branch.
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uncondBranch(instPC.instAddr(), bp_history);
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uncondBranch(tid, instPC.instAddr(), bp_history);
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if (inst->isReturn() && RAS[tid].empty()) {
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DPRINTF(Branch, "[tid:%i] RAS is empty, predicting "
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@ -356,7 +356,7 @@ BPredUnit::predictInOrder(const StaticInstPtr &inst, const InstSeqNum &seqNum,
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} else {
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++condPredicted;
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pred_taken = lookup(predPC.instAddr(), bp_history);
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pred_taken = lookup(tid, predPC.instAddr(), bp_history);
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}
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PredictorHistory predict_record(seqNum, predPC.instAddr(), pred_taken,
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@ -451,10 +451,11 @@ BPredUnit::update(const InstSeqNum &done_sn, ThreadID tid)
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predHist[tid].back().seqNum <= done_sn) {
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// Update the branch predictor with the correct results.
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if (!predHist[tid].back().wasSquashed) {
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update(predHist[tid].back().pc, predHist[tid].back().predTaken,
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update(tid, predHist[tid].back().pc,
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predHist[tid].back().predTaken,
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predHist[tid].back().bpHistory, false);
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} else {
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retireSquashed(predHist[tid].back().bpHistory);
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retireSquashed(tid, predHist[tid].back().bpHistory);
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}
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predHist[tid].pop_back();
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@ -485,7 +486,7 @@ BPredUnit::squash(const InstSeqNum &squashed_sn, ThreadID tid)
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}
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// This call should delete the bpHistory.
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squash(pred_hist.front().bpHistory);
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squash(tid, pred_hist.front().bpHistory);
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DPRINTF(Branch, "[tid:%i]: Removing history for [sn:%i] "
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"PC %s.\n", tid, pred_hist.front().seqNum,
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@ -550,9 +551,9 @@ BPredUnit::squash(const InstSeqNum &squashed_sn,
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}
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// Have to get GHR here because the update deletes bpHistory
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unsigned ghr = getGHR(hist_it->bpHistory);
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unsigned ghr = getGHR(tid, hist_it->bpHistory);
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update((*hist_it).pc, actually_taken,
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update(tid, (*hist_it).pc, actually_taken,
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pred_hist.front().bpHistory, true);
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hist_it->wasSquashed = true;
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@ -98,7 +98,7 @@ class BPredUnit : public SimObject
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TheISA::PCState &predPC, ThreadID tid);
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// @todo: Rename this function.
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virtual void uncondBranch(Addr pc, void * &bp_history) = 0;
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virtual void uncondBranch(ThreadID tid, Addr pc, void * &bp_history) = 0;
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/**
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* Tells the branch predictor to commit any updates until the given
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@ -133,7 +133,7 @@ class BPredUnit : public SimObject
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* @param bp_history Pointer to the history object. The predictor
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* will need to update any state and delete the object.
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*/
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virtual void squash(void *bp_history) = 0;
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virtual void squash(ThreadID tid, void *bp_history) = 0;
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/**
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* Looks up a given PC in the BP to see if it is taken or not taken.
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@ -142,7 +142,7 @@ class BPredUnit : public SimObject
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* has the branch predictor state associated with the lookup.
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* @return Whether the branch is taken or not taken.
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*/
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virtual bool lookup(Addr instPC, void * &bp_history) = 0;
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virtual bool lookup(ThreadID tid, Addr instPC, void * &bp_history) = 0;
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/**
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* If a branch is not taken, because the BTB address is invalid or missing,
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@ -152,7 +152,7 @@ class BPredUnit : public SimObject
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* @param bp_history Pointer that will be set to an object that
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* has the branch predictor state associated with the lookup.
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*/
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virtual void btbUpdate(Addr instPC, void * &bp_history) = 0;
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virtual void btbUpdate(ThreadID tid, Addr instPC, void * &bp_history) = 0;
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/**
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* Looks up a given PC in the BTB to see if a matching entry exists.
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@ -180,15 +180,15 @@ class BPredUnit : public SimObject
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* squash operation.
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* @todo Make this update flexible enough to handle a global predictor.
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*/
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virtual void update(Addr instPC, bool taken, void *bp_history,
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bool squashed) = 0;
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virtual void update(ThreadID tid, Addr instPC, bool taken,
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void *bp_history, bool squashed) = 0;
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/**
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* Deletes the associated history with a branch, performs no predictor
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* updates. Used for branches that mispredict and update tables but
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* are still speculative and later retire.
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* @param bp_history History to delete associated with this predictor
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*/
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virtual void retireSquashed(void *bp_history) = 0;
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virtual void retireSquashed(ThreadID tid, void *bp_history) = 0;
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/**
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* Updates the BTB with the target of a branch.
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@ -199,7 +199,7 @@ class BPredUnit : public SimObject
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{ BTB.update(instPC, target, 0); }
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virtual unsigned getGHR(void* bp_history) const { return 0; }
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virtual unsigned getGHR(ThreadID tid, void* bp_history) const { return 0; }
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void dump();
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@ -52,6 +52,7 @@ TournamentBP::TournamentBP(const TournamentBPParams *params)
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localHistoryBits(ceilLog2(params->localPredictorSize)),
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globalPredictorSize(params->globalPredictorSize),
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globalCtrBits(params->globalCtrBits),
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globalHistory(params->numThreads, 0),
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globalHistoryBits(
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ceilLog2(params->globalPredictorSize) >
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ceilLog2(params->choicePredictorSize) ?
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@ -92,8 +93,6 @@ TournamentBP::TournamentBP(const TournamentBPParams *params)
|
|||
for (int i = 0; i < globalPredictorSize; ++i)
|
||||
globalCtrs[i].setBits(globalCtrBits);
|
||||
|
||||
//Clear the global history
|
||||
globalHistory = 0;
|
||||
// Set up the global history mask
|
||||
// this is equivalent to mask(log2(globalPredictorSize)
|
||||
globalHistoryMask = globalPredictorSize - 1;
|
||||
|
|
@ -145,18 +144,18 @@ TournamentBP::calcLocHistIdx(Addr &branch_addr)
|
|||
|
||||
inline
|
||||
void
|
||||
TournamentBP::updateGlobalHistTaken()
|
||||
TournamentBP::updateGlobalHistTaken(ThreadID tid)
|
||||
{
|
||||
globalHistory = (globalHistory << 1) | 1;
|
||||
globalHistory = globalHistory & historyRegisterMask;
|
||||
globalHistory[tid] = (globalHistory[tid] << 1) | 1;
|
||||
globalHistory[tid] = globalHistory[tid] & historyRegisterMask;
|
||||
}
|
||||
|
||||
inline
|
||||
void
|
||||
TournamentBP::updateGlobalHistNotTaken()
|
||||
TournamentBP::updateGlobalHistNotTaken(ThreadID tid)
|
||||
{
|
||||
globalHistory = (globalHistory << 1);
|
||||
globalHistory = globalHistory & historyRegisterMask;
|
||||
globalHistory[tid] = (globalHistory[tid] << 1);
|
||||
globalHistory[tid] = globalHistory[tid] & historyRegisterMask;
|
||||
}
|
||||
|
||||
inline
|
||||
|
|
@ -177,18 +176,18 @@ TournamentBP::updateLocalHistNotTaken(unsigned local_history_idx)
|
|||
|
||||
|
||||
void
|
||||
TournamentBP::btbUpdate(Addr branch_addr, void * &bp_history)
|
||||
TournamentBP::btbUpdate(ThreadID tid, Addr branch_addr, void * &bp_history)
|
||||
{
|
||||
unsigned local_history_idx = calcLocHistIdx(branch_addr);
|
||||
//Update Global History to Not Taken (clear LSB)
|
||||
globalHistory &= (historyRegisterMask & ~ULL(1));
|
||||
globalHistory[tid] &= (historyRegisterMask & ~ULL(1));
|
||||
//Update Local History to Not Taken
|
||||
localHistoryTable[local_history_idx] =
|
||||
localHistoryTable[local_history_idx] & (localPredictorMask & ~ULL(1));
|
||||
}
|
||||
|
||||
bool
|
||||
TournamentBP::lookup(Addr branch_addr, void * &bp_history)
|
||||
TournamentBP::lookup(ThreadID tid, Addr branch_addr, void * &bp_history)
|
||||
{
|
||||
bool local_prediction;
|
||||
unsigned local_history_idx;
|
||||
|
|
@ -204,16 +203,16 @@ TournamentBP::lookup(Addr branch_addr, void * &bp_history)
|
|||
local_prediction = localCtrs[local_predictor_idx].read() > localThreshold;
|
||||
|
||||
//Lookup in the global predictor to get its branch prediction
|
||||
global_prediction =
|
||||
globalCtrs[globalHistory & globalHistoryMask].read() > globalThreshold;
|
||||
global_prediction = globalThreshold <
|
||||
globalCtrs[globalHistory[tid] & globalHistoryMask].read();
|
||||
|
||||
//Lookup in the choice predictor to see which one to use
|
||||
choice_prediction =
|
||||
choiceCtrs[globalHistory & choiceHistoryMask].read() > choiceThreshold;
|
||||
choice_prediction = choiceThreshold <
|
||||
choiceCtrs[globalHistory[tid] & choiceHistoryMask].read();
|
||||
|
||||
// Create BPHistory and pass it back to be recorded.
|
||||
BPHistory *history = new BPHistory;
|
||||
history->globalHistory = globalHistory;
|
||||
history->globalHistory = globalHistory[tid];
|
||||
history->localPredTaken = local_prediction;
|
||||
history->globalPredTaken = global_prediction;
|
||||
history->globalUsed = choice_prediction;
|
||||
|
|
@ -227,21 +226,21 @@ TournamentBP::lookup(Addr branch_addr, void * &bp_history)
|
|||
// all histories.
|
||||
if (choice_prediction) {
|
||||
if (global_prediction) {
|
||||
updateGlobalHistTaken();
|
||||
updateGlobalHistTaken(tid);
|
||||
updateLocalHistTaken(local_history_idx);
|
||||
return true;
|
||||
} else {
|
||||
updateGlobalHistNotTaken();
|
||||
updateGlobalHistNotTaken(tid);
|
||||
updateLocalHistNotTaken(local_history_idx);
|
||||
return false;
|
||||
}
|
||||
} else {
|
||||
if (local_prediction) {
|
||||
updateGlobalHistTaken();
|
||||
updateGlobalHistTaken(tid);
|
||||
updateLocalHistTaken(local_history_idx);
|
||||
return true;
|
||||
} else {
|
||||
updateGlobalHistNotTaken();
|
||||
updateGlobalHistNotTaken(tid);
|
||||
updateLocalHistNotTaken(local_history_idx);
|
||||
return false;
|
||||
}
|
||||
|
|
@ -249,11 +248,11 @@ TournamentBP::lookup(Addr branch_addr, void * &bp_history)
|
|||
}
|
||||
|
||||
void
|
||||
TournamentBP::uncondBranch(Addr pc, void * &bp_history)
|
||||
TournamentBP::uncondBranch(ThreadID tid, Addr pc, void * &bp_history)
|
||||
{
|
||||
// Create BPHistory and pass it back to be recorded.
|
||||
BPHistory *history = new BPHistory;
|
||||
history->globalHistory = globalHistory;
|
||||
history->globalHistory = globalHistory[tid];
|
||||
history->localPredTaken = true;
|
||||
history->globalPredTaken = true;
|
||||
history->globalUsed = true;
|
||||
|
|
@ -261,12 +260,12 @@ TournamentBP::uncondBranch(Addr pc, void * &bp_history)
|
|||
history->localHistory = invalidPredictorIndex;
|
||||
bp_history = static_cast<void *>(history);
|
||||
|
||||
updateGlobalHistTaken();
|
||||
updateGlobalHistTaken(tid);
|
||||
}
|
||||
|
||||
void
|
||||
TournamentBP::update(Addr branch_addr, bool taken, void *bp_history,
|
||||
bool squashed)
|
||||
TournamentBP::update(ThreadID tid, Addr branch_addr, bool taken,
|
||||
void *bp_history, bool squashed)
|
||||
{
|
||||
unsigned local_history_idx;
|
||||
unsigned local_predictor_idx M5_VAR_USED;
|
||||
|
|
@ -332,15 +331,15 @@ TournamentBP::update(Addr branch_addr, bool taken, void *bp_history,
|
|||
}
|
||||
if (squashed) {
|
||||
if (taken) {
|
||||
globalHistory = (history->globalHistory << 1) | 1;
|
||||
globalHistory = globalHistory & historyRegisterMask;
|
||||
globalHistory[tid] = (history->globalHistory << 1) | 1;
|
||||
globalHistory[tid] = globalHistory[tid] & historyRegisterMask;
|
||||
if (old_local_pred_valid) {
|
||||
localHistoryTable[local_history_idx] =
|
||||
(history->localHistory << 1) | 1;
|
||||
}
|
||||
} else {
|
||||
globalHistory = (history->globalHistory << 1);
|
||||
globalHistory = globalHistory & historyRegisterMask;
|
||||
globalHistory[tid] = (history->globalHistory << 1);
|
||||
globalHistory[tid] = globalHistory[tid] & historyRegisterMask;
|
||||
if (old_local_pred_valid) {
|
||||
localHistoryTable[local_history_idx] =
|
||||
history->localHistory << 1;
|
||||
|
|
@ -359,19 +358,19 @@ TournamentBP::update(Addr branch_addr, bool taken, void *bp_history,
|
|||
}
|
||||
|
||||
void
|
||||
TournamentBP::retireSquashed(void *bp_history)
|
||||
TournamentBP::retireSquashed(ThreadID tid, void *bp_history)
|
||||
{
|
||||
BPHistory *history = static_cast<BPHistory *>(bp_history);
|
||||
delete history;
|
||||
}
|
||||
|
||||
void
|
||||
TournamentBP::squash(void *bp_history)
|
||||
TournamentBP::squash(ThreadID tid, void *bp_history)
|
||||
{
|
||||
BPHistory *history = static_cast<BPHistory *>(bp_history);
|
||||
|
||||
// Restore global history to state prior to this branch.
|
||||
globalHistory = history->globalHistory;
|
||||
globalHistory[tid] = history->globalHistory;
|
||||
|
||||
// Restore local history
|
||||
if (history->localHistoryIdx != invalidPredictorIndex) {
|
||||
|
|
@ -389,7 +388,7 @@ TournamentBPParams::create()
|
|||
}
|
||||
|
||||
unsigned
|
||||
TournamentBP::getGHR(void *bp_history) const
|
||||
TournamentBP::getGHR(ThreadID tid, void *bp_history) const
|
||||
{
|
||||
return static_cast<BPHistory *>(bp_history)->globalHistory;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -77,7 +77,7 @@ class TournamentBP : public BPredUnit
|
|||
* @param bp_history Pointer that will be set to the BPHistory object.
|
||||
* @return Whether or not the branch is taken.
|
||||
*/
|
||||
bool lookup(Addr branch_addr, void * &bp_history);
|
||||
bool lookup(ThreadID tid, Addr branch_addr, void * &bp_history);
|
||||
|
||||
/**
|
||||
* Records that there was an unconditional branch, and modifies
|
||||
|
|
@ -85,7 +85,7 @@ class TournamentBP : public BPredUnit
|
|||
* global history stored in it.
|
||||
* @param bp_history Pointer that will be set to the BPHistory object.
|
||||
*/
|
||||
void uncondBranch(Addr pc, void * &bp_history);
|
||||
void uncondBranch(ThreadID tid, Addr pc, void * &bp_history);
|
||||
/**
|
||||
* Updates the branch predictor to Not Taken if a BTB entry is
|
||||
* invalid or not found.
|
||||
|
|
@ -93,7 +93,7 @@ class TournamentBP : public BPredUnit
|
|||
* @param bp_history Pointer to any bp history state.
|
||||
* @return Whether or not the branch is taken.
|
||||
*/
|
||||
void btbUpdate(Addr branch_addr, void * &bp_history);
|
||||
void btbUpdate(ThreadID tid, Addr branch_addr, void * &bp_history);
|
||||
/**
|
||||
* Updates the branch predictor with the actual result of a branch.
|
||||
* @param branch_addr The address of the branch to update.
|
||||
|
|
@ -103,21 +103,19 @@ class TournamentBP : public BPredUnit
|
|||
* @param squashed is set when this function is called during a squash
|
||||
* operation.
|
||||
*/
|
||||
void update(Addr branch_addr, bool taken, void *bp_history, bool squashed);
|
||||
void update(ThreadID tid, Addr branch_addr, bool taken, void *bp_history,
|
||||
bool squashed);
|
||||
|
||||
void retireSquashed(void *bp_history);
|
||||
void retireSquashed(ThreadID tid, void *bp_history);
|
||||
|
||||
/**
|
||||
* Restores the global branch history on a squash.
|
||||
* @param bp_history Pointer to the BPHistory object that has the
|
||||
* previous global branch history in it.
|
||||
*/
|
||||
void squash(void *bp_history);
|
||||
void squash(ThreadID tid, void *bp_history);
|
||||
|
||||
unsigned getGHR(void *bp_history) const;
|
||||
|
||||
/** Returns the global history. */
|
||||
inline unsigned readGlobalHist() { return globalHistory; }
|
||||
unsigned getGHR(ThreadID tid, void *bp_history) const;
|
||||
|
||||
private:
|
||||
/**
|
||||
|
|
@ -134,10 +132,10 @@ class TournamentBP : public BPredUnit
|
|||
inline unsigned calcLocHistIdx(Addr &branch_addr);
|
||||
|
||||
/** Updates global history as taken. */
|
||||
inline void updateGlobalHistTaken();
|
||||
inline void updateGlobalHistTaken(ThreadID tid);
|
||||
|
||||
/** Updates global history as not taken. */
|
||||
inline void updateGlobalHistNotTaken();
|
||||
inline void updateGlobalHistNotTaken(ThreadID tid);
|
||||
|
||||
/**
|
||||
* Updates local histories as taken.
|
||||
|
|
@ -211,7 +209,7 @@ class TournamentBP : public BPredUnit
|
|||
/** Global history register. Contains as much history as specified by
|
||||
* globalHistoryBits. Actual number of bits used is determined by
|
||||
* globalHistoryMask and choiceHistoryMask. */
|
||||
unsigned globalHistory;
|
||||
std::vector<unsigned> globalHistory;
|
||||
|
||||
/** Number of bits for the global history. Determines maximum number of
|
||||
entries in global and choice predictor tables. */
|
||||
|
|
|
|||
Loading…
Reference in a new issue