diff options
Diffstat (limited to 'src/cpu/o3/bpred_unit.hh')
-rw-r--r-- | src/cpu/o3/bpred_unit.hh | 64 |
1 files changed, 46 insertions, 18 deletions
diff --git a/src/cpu/o3/bpred_unit.hh b/src/cpu/o3/bpred_unit.hh index 39a88a3ce..2c0a39565 100644 --- a/src/cpu/o3/bpred_unit.hh +++ b/src/cpu/o3/bpred_unit.hh @@ -48,16 +48,25 @@ * and the BTB. */ template<class Impl> -class TwobitBPredUnit +class BPredUnit { - public: + private: typedef typename Impl::Params Params; typedef typename Impl::DynInstPtr DynInstPtr; + enum PredType { + Local, + Tournament + }; + + PredType predictor; + + public: + /** * @param params The params object, that has the size of the BP and BTB. */ - TwobitBPredUnit(Params *params); + BPredUnit(Params *params); /** * Registers statistics. @@ -78,6 +87,9 @@ class TwobitBPredUnit */ bool predict(DynInstPtr &inst, Addr &PC, unsigned tid); + // @todo: Rename this function. + void BPUncond(void * &bp_history); + /** * Tells the branch predictor to commit any updates until the given * sequence number. @@ -107,12 +119,19 @@ class TwobitBPredUnit bool actually_taken, unsigned tid); /** + * @param bp_history Pointer to the history object. The predictor + * will need to update any state and delete the object. + */ + void BPSquash(void *bp_history); + + /** * Looks up a given PC in the BP to see if it is taken or not taken. * @param inst_PC The PC to look up. + * @param bp_history Pointer that will be set to an object that + * has the branch predictor state associated with the lookup. * @return Whether the branch is taken or not taken. */ - bool BPLookup(Addr &inst_PC) - { return BP.lookup(inst_PC); } + bool BPLookup(Addr &inst_PC, void * &bp_history); /** * Looks up a given PC in the BTB to see if a matching entry exists. @@ -134,10 +153,11 @@ class TwobitBPredUnit * Updates the BP with taken/not taken information. * @param inst_PC The branch's PC that will be updated. * @param taken Whether the branch was taken or not taken. + * @param bp_history Pointer to the branch predictor state that is + * associated with the branch lookup that is being updated. * @todo Make this update flexible enough to handle a global predictor. */ - void BPUpdate(Addr &inst_PC, bool taken) - { BP.update(inst_PC, taken); } + void BPUpdate(Addr &inst_PC, bool taken, void *bp_history); /** * Updates the BTB with the target of a branch. @@ -147,18 +167,20 @@ class TwobitBPredUnit void BTBUpdate(Addr &inst_PC, Addr &target_PC) { BTB.update(inst_PC, target_PC,0); } + void dump(); + private: struct PredictorHistory { /** - * Makes a predictor history struct that contains a sequence number, - * the PC of its instruction, and whether or not it was predicted - * taken. + * Makes a predictor history struct that contains any + * information needed to update the predictor, BTB, and RAS. */ PredictorHistory(const InstSeqNum &seq_num, const Addr &inst_PC, - const bool pred_taken, const unsigned _tid) - : seqNum(seq_num), PC(inst_PC), RASTarget(0), globalHistory(0), + const bool pred_taken, void *bp_history, + const unsigned _tid) + : seqNum(seq_num), PC(inst_PC), RASTarget(0), RASIndex(0), tid(_tid), predTaken(pred_taken), usedRAS(0), - wasCall(0) + wasCall(0), bpHistory(bp_history) { } /** The sequence number for the predictor history entry. */ @@ -170,9 +192,6 @@ class TwobitBPredUnit /** The RAS target (only valid if a return). */ Addr RASTarget; - /** The global history at the time this entry was created. */ - unsigned globalHistory; - /** The RAS index of the instruction (only valid if a call). */ unsigned RASIndex; @@ -187,6 +206,12 @@ class TwobitBPredUnit /** Whether or not the instruction was a call. */ bool wasCall; + + /** Pointer to the history object passed back from the branch + * predictor. It is used to update or restore state of the + * branch predictor. + */ + void *bpHistory; }; typedef std::list<PredictorHistory> History; @@ -198,8 +223,11 @@ class TwobitBPredUnit */ History predHist[Impl::MaxThreads]; - /** The branch predictor. */ - DefaultBP BP; + /** The local branch predictor. */ + LocalBP *localBP; + + /** The tournament branch predictor. */ + TournamentBP *tournamentBP; /** The BTB. */ DefaultBTB BTB; |