diff options
author | Kevin Lim <ktlim@umich.edu> | 2006-05-30 14:17:41 -0400 |
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committer | Kevin Lim <ktlim@umich.edu> | 2006-05-30 14:17:41 -0400 |
commit | 4a5b51b516853c9fcaabc44caacdd7e8e93dc0ef (patch) | |
tree | 4b7d92408a2b74a16ae6f7b4167ded00079355ef /src/cpu/o3/bpred_unit.hh | |
parent | d308055afc1ace1f321b76e8a85a9a45165da2ce (diff) | |
parent | f1fab2a4469d6cb2e55ebac15da02f8c1fcb7055 (diff) | |
download | gem5-4a5b51b516853c9fcaabc44caacdd7e8e93dc0ef.tar.xz |
Merge ktlim@zizzer:/bk/m5
into zamp.eecs.umich.edu:/z/ktlim2/clean/newmem
SConstruct:
src/SConscript:
src/arch/SConscript:
src/arch/alpha/faults.cc:
src/arch/alpha/tlb.cc:
src/base/traceflags.py:
src/cpu/SConscript:
src/cpu/base.cc:
src/cpu/base.hh:
src/cpu/base_dyn_inst.cc:
src/cpu/cpu_exec_context.cc:
src/cpu/cpu_exec_context.hh:
src/cpu/exec_context.hh:
src/cpu/o3/alpha_cpu.hh:
src/cpu/o3/alpha_cpu_impl.hh:
src/cpu/o3/alpha_dyn_inst.hh:
src/cpu/o3/cpu.cc:
src/cpu/o3/cpu.hh:
src/cpu/o3/regfile.hh:
src/cpu/ozone/cpu.hh:
src/cpu/simple/base.cc:
src/cpu/base_dyn_inst.hh:
src/cpu/o3/2bit_local_pred.cc:
src/cpu/o3/2bit_local_pred.hh:
src/cpu/o3/alpha_cpu.cc:
src/cpu/o3/alpha_cpu_builder.cc:
src/cpu/o3/alpha_dyn_inst.cc:
src/cpu/o3/alpha_dyn_inst_impl.hh:
src/cpu/o3/alpha_impl.hh:
src/cpu/o3/alpha_params.hh:
src/cpu/o3/bpred_unit.cc:
src/cpu/o3/bpred_unit.hh:
src/cpu/o3/bpred_unit_impl.hh:
src/cpu/o3/btb.cc:
src/cpu/o3/btb.hh:
src/cpu/o3/comm.hh:
src/cpu/o3/commit.cc:
src/cpu/o3/commit.hh:
src/cpu/o3/commit_impl.hh:
src/cpu/o3/cpu_policy.hh:
src/cpu/o3/decode.cc:
src/cpu/o3/decode.hh:
src/cpu/o3/decode_impl.hh:
src/cpu/o3/fetch.cc:
src/cpu/o3/fetch.hh:
src/cpu/o3/fetch_impl.hh:
src/cpu/o3/free_list.cc:
src/cpu/o3/free_list.hh:
src/cpu/o3/iew.cc:
src/cpu/o3/iew.hh:
src/cpu/o3/iew_impl.hh:
src/cpu/o3/inst_queue.cc:
src/cpu/o3/inst_queue.hh:
src/cpu/o3/inst_queue_impl.hh:
src/cpu/o3/mem_dep_unit.cc:
src/cpu/o3/mem_dep_unit.hh:
src/cpu/o3/mem_dep_unit_impl.hh:
src/cpu/o3/ras.cc:
src/cpu/o3/ras.hh:
src/cpu/o3/rename.cc:
src/cpu/o3/rename.hh:
src/cpu/o3/rename_impl.hh:
src/cpu/o3/rename_map.cc:
src/cpu/o3/rename_map.hh:
src/cpu/o3/rob.cc:
src/cpu/o3/rob.hh:
src/cpu/o3/rob_impl.hh:
src/cpu/o3/sat_counter.cc:
src/cpu/o3/sat_counter.hh:
src/cpu/o3/store_set.cc:
src/cpu/o3/store_set.hh:
src/cpu/o3/tournament_pred.cc:
src/cpu/o3/tournament_pred.hh:
Hand merges.
--HG--
rename : build/SConstruct => SConstruct
rename : SConscript => src/SConscript
rename : arch/alpha/ev5.cc => src/arch/alpha/ev5.cc
rename : arch/alpha/isa/decoder.isa => src/arch/alpha/isa/decoder.isa
rename : arch/alpha/isa/pal.isa => src/arch/alpha/isa/pal.isa
rename : base/traceflags.py => src/base/traceflags.py
rename : cpu/SConscript => src/cpu/SConscript
rename : cpu/base.cc => src/cpu/base.cc
rename : cpu/base.hh => src/cpu/base.hh
rename : cpu/base_dyn_inst.cc => src/cpu/base_dyn_inst.cc
rename : cpu/base_dyn_inst.hh => src/cpu/base_dyn_inst.hh
rename : cpu/cpu_exec_context.cc => src/cpu/cpu_exec_context.cc
rename : cpu/cpu_exec_context.hh => src/cpu/cpu_exec_context.hh
rename : cpu/cpu_models.py => src/cpu/cpu_models.py
rename : cpu/exec_context.hh => src/cpu/exec_context.hh
rename : cpu/exetrace.cc => src/cpu/exetrace.cc
rename : cpu/exetrace.hh => src/cpu/exetrace.hh
rename : cpu/inst_seq.hh => src/cpu/inst_seq.hh
rename : cpu/o3/2bit_local_pred.cc => src/cpu/o3/2bit_local_pred.cc
rename : cpu/o3/2bit_local_pred.hh => src/cpu/o3/2bit_local_pred.hh
rename : cpu/o3/alpha_cpu.hh => src/cpu/o3/alpha_cpu.hh
rename : cpu/o3/alpha_cpu_builder.cc => src/cpu/o3/alpha_cpu_builder.cc
rename : cpu/o3/alpha_cpu_impl.hh => src/cpu/o3/alpha_cpu_impl.hh
rename : cpu/o3/alpha_dyn_inst.hh => src/cpu/o3/alpha_dyn_inst.hh
rename : cpu/o3/alpha_dyn_inst_impl.hh => src/cpu/o3/alpha_dyn_inst_impl.hh
rename : cpu/o3/alpha_impl.hh => src/cpu/o3/alpha_impl.hh
rename : cpu/o3/alpha_params.hh => src/cpu/o3/alpha_params.hh
rename : cpu/o3/bpred_unit.cc => src/cpu/o3/bpred_unit.cc
rename : cpu/o3/bpred_unit.hh => src/cpu/o3/bpred_unit.hh
rename : cpu/o3/bpred_unit_impl.hh => src/cpu/o3/bpred_unit_impl.hh
rename : cpu/o3/btb.cc => src/cpu/o3/btb.cc
rename : cpu/o3/btb.hh => src/cpu/o3/btb.hh
rename : cpu/o3/comm.hh => src/cpu/o3/comm.hh
rename : cpu/o3/commit.cc => src/cpu/o3/commit.cc
rename : cpu/o3/commit.hh => src/cpu/o3/commit.hh
rename : cpu/o3/commit_impl.hh => src/cpu/o3/commit_impl.hh
rename : cpu/o3/cpu.cc => src/cpu/o3/cpu.cc
rename : cpu/o3/cpu.hh => src/cpu/o3/cpu.hh
rename : cpu/o3/cpu_policy.hh => src/cpu/o3/cpu_policy.hh
rename : cpu/o3/decode.cc => src/cpu/o3/decode.cc
rename : cpu/o3/decode.hh => src/cpu/o3/decode.hh
rename : cpu/o3/decode_impl.hh => src/cpu/o3/decode_impl.hh
rename : cpu/o3/fetch.cc => src/cpu/o3/fetch.cc
rename : cpu/o3/fetch.hh => src/cpu/o3/fetch.hh
rename : cpu/o3/fetch_impl.hh => src/cpu/o3/fetch_impl.hh
rename : cpu/o3/free_list.cc => src/cpu/o3/free_list.cc
rename : cpu/o3/free_list.hh => src/cpu/o3/free_list.hh
rename : cpu/o3/iew.cc => src/cpu/o3/iew.cc
rename : cpu/o3/iew.hh => src/cpu/o3/iew.hh
rename : cpu/o3/iew_impl.hh => src/cpu/o3/iew_impl.hh
rename : cpu/o3/inst_queue.cc => src/cpu/o3/inst_queue.cc
rename : cpu/o3/inst_queue.hh => src/cpu/o3/inst_queue.hh
rename : cpu/o3/inst_queue_impl.hh => src/cpu/o3/inst_queue_impl.hh
rename : cpu/o3/mem_dep_unit.cc => src/cpu/o3/mem_dep_unit.cc
rename : cpu/o3/mem_dep_unit.hh => src/cpu/o3/mem_dep_unit.hh
rename : cpu/o3/mem_dep_unit_impl.hh => src/cpu/o3/mem_dep_unit_impl.hh
rename : cpu/o3/ras.cc => src/cpu/o3/ras.cc
rename : cpu/o3/ras.hh => src/cpu/o3/ras.hh
rename : cpu/o3/regfile.hh => src/cpu/o3/regfile.hh
rename : cpu/o3/rename.cc => src/cpu/o3/rename.cc
rename : cpu/o3/rename.hh => src/cpu/o3/rename.hh
rename : cpu/o3/rename_impl.hh => src/cpu/o3/rename_impl.hh
rename : cpu/o3/rename_map.cc => src/cpu/o3/rename_map.cc
rename : cpu/o3/rename_map.hh => src/cpu/o3/rename_map.hh
rename : cpu/o3/rob.hh => src/cpu/o3/rob.hh
rename : cpu/o3/rob_impl.hh => src/cpu/o3/rob_impl.hh
rename : cpu/o3/sat_counter.hh => src/cpu/o3/sat_counter.hh
rename : cpu/o3/store_set.cc => src/cpu/o3/store_set.cc
rename : cpu/o3/store_set.hh => src/cpu/o3/store_set.hh
rename : cpu/o3/tournament_pred.cc => src/cpu/o3/tournament_pred.cc
rename : cpu/o3/tournament_pred.hh => src/cpu/o3/tournament_pred.hh
rename : cpu/ozone/cpu.cc => src/cpu/ozone/cpu.cc
rename : cpu/ozone/cpu.hh => src/cpu/ozone/cpu.hh
rename : cpu/ozone/cpu_impl.hh => src/cpu/ozone/cpu_impl.hh
rename : cpu/static_inst.hh => src/cpu/static_inst.hh
rename : kern/system_events.cc => src/kern/system_events.cc
rename : kern/tru64/tru64.hh => src/kern/tru64/tru64.hh
rename : python/m5/objects/AlphaFullCPU.py => src/python/m5/objects/AlphaFullCPU.py
rename : sim/pseudo_inst.cc => src/sim/pseudo_inst.cc
extra : convert_revision : ff351fc0e3a7c0f23e59fdbec33d8209eb9280be
Diffstat (limited to 'src/cpu/o3/bpred_unit.hh')
-rw-r--r-- | src/cpu/o3/bpred_unit.hh | 161 |
1 files changed, 127 insertions, 34 deletions
diff --git a/src/cpu/o3/bpred_unit.hh b/src/cpu/o3/bpred_unit.hh index 2725684f7..b7814b2e9 100644 --- a/src/cpu/o3/bpred_unit.hh +++ b/src/cpu/o3/bpred_unit.hh @@ -26,8 +26,8 @@ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ -#ifndef __BPRED_UNIT_HH__ -#define __BPRED_UNIT_HH__ +#ifndef __CPU_O3_BPRED_UNIT_HH__ +#define __CPU_O3_BPRED_UNIT_HH__ // For Addr type. #include "arch/isa_traits.hh" @@ -35,20 +35,15 @@ #include "cpu/inst_seq.hh" #include "cpu/o3/2bit_local_pred.hh" -#include "cpu/o3/tournament_pred.hh" #include "cpu/o3/btb.hh" #include "cpu/o3/ras.hh" +#include "cpu/o3/tournament_pred.hh" #include <list> /** * Basically a wrapper class to hold both the branch predictor - * and the BTB. Right now I'm unsure of the implementation; it would - * be nicer to have something closer to the CPUPolicy or the Impl where - * this is just typedefs, but it forces the upper level stages to be - * aware of the constructors of the BP and the BTB. The nicer thing - * to do is have this templated on the Impl, accept the usual Params - * object, and be able to call the constructors on the BP and BTB. + * and the BTB. */ template<class Impl> class TwobitBPredUnit @@ -57,77 +52,175 @@ class TwobitBPredUnit typedef typename Impl::Params Params; typedef typename Impl::DynInstPtr DynInstPtr; - TwobitBPredUnit(Params ¶ms); + /** + * @param params The params object, that has the size of the BP and BTB. + */ + TwobitBPredUnit(Params *params); + /** + * Registers statistics. + */ void regStats(); - bool predict(DynInstPtr &inst, Addr &PC); - - void update(const InstSeqNum &done_sn); - - void squash(const InstSeqNum &squashed_sn); - + void switchOut(); + + void takeOverFrom(); + + /** + * Predicts whether or not the instruction is a taken branch, and the + * target of the branch if it is taken. + * @param inst The branch instruction. + * @param PC The predicted PC is passed back through this parameter. + * @param tid The thread id. + * @return Returns if the branch is taken or not. + */ + bool predict(DynInstPtr &inst, Addr &PC, unsigned tid); + + /** + * Tells the branch predictor to commit any updates until the given + * sequence number. + * @param done_sn The sequence number to commit any older updates up until. + * @param tid The thread id. + */ + void update(const InstSeqNum &done_sn, unsigned tid); + + /** + * Squashes all outstanding updates until a given sequence number. + * @param squashed_sn The sequence number to squash any younger updates up + * until. + * @param tid The thread id. + */ + void squash(const InstSeqNum &squashed_sn, unsigned tid); + + /** + * Squashes all outstanding updates until a given sequence number, and + * corrects that sn's update with the proper address and taken/not taken. + * @param squashed_sn The sequence number to squash any younger updates up + * until. + * @param corr_target The correct branch target. + * @param actually_taken The correct branch direction. + * @param tid The thread id. + */ void squash(const InstSeqNum &squashed_sn, const Addr &corr_target, - bool actually_taken); + bool actually_taken, unsigned tid); + /** + * 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. + * @return Whether the branch is taken or not taken. + */ bool BPLookup(Addr &inst_PC) { return BP.lookup(inst_PC); } + /** + * Looks up a given PC in the BTB to see if a matching entry exists. + * @param inst_PC The PC to look up. + * @return Whether the BTB contains the given PC. + */ bool BTBValid(Addr &inst_PC) - { return BTB.valid(inst_PC); } + { return BTB.valid(inst_PC, 0); } + /** + * Looks up a given PC in the BTB to get the predicted target. + * @param inst_PC The PC to look up. + * @return The address of the target of the branch. + */ Addr BTBLookup(Addr &inst_PC) - { return BTB.lookup(inst_PC); } - - // Will want to include global history. + { return BTB.lookup(inst_PC, 0); } + + /** + * 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. + * @todo Make this update flexible enough to handle a global predictor. + */ void BPUpdate(Addr &inst_PC, bool taken) { BP.update(inst_PC, taken); } + /** + * Updates the BTB with the target of a branch. + * @param inst_PC The branch's PC that will be updated. + * @param target_PC The branch's target that will be added to the BTB. + */ void BTBUpdate(Addr &inst_PC, Addr &target_PC) - { BTB.update(inst_PC, target_PC); } + { BTB.update(inst_PC, target_PC,0); } 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. + */ PredictorHistory(const InstSeqNum &seq_num, const Addr &inst_PC, - const bool pred_taken) - : seqNum(seq_num), PC(inst_PC), predTaken(pred_taken), - globalHistory(0), usedRAS(0), wasCall(0), RASIndex(0), - RASTarget(0) + const bool pred_taken, const unsigned _tid) + : seqNum(seq_num), PC(inst_PC), RASTarget(0), globalHistory(0), + RASIndex(0), tid(_tid), predTaken(pred_taken), usedRAS(0), + wasCall(0) { } + /** The sequence number for the predictor history entry. */ InstSeqNum seqNum; + /** The PC associated with the sequence number. */ Addr PC; - bool predTaken; + /** The RAS target (only valid if a return). */ + Addr RASTarget; + /** The global history at the time this entry was created. */ unsigned globalHistory; - bool usedRAS; + /** The RAS index of the instruction (only valid if a call). */ + unsigned RASIndex; - bool wasCall; + /** The thread id. */ + unsigned tid; - unsigned RASIndex; + /** Whether or not it was predicted taken. */ + bool predTaken; - Addr RASTarget; + /** Whether or not the RAS was used. */ + bool usedRAS; + + /** Whether or not the instruction was a call. */ + bool wasCall; }; - std::list<PredictorHistory> predHist; + typedef std::list<PredictorHistory> History; + + /** + * The per-thread predictor history. This is used to update the predictor + * as instructions are committed, or restore it to the proper state after + * a squash. + */ + History predHist[Impl::MaxThreads]; + /** The branch predictor. */ DefaultBP BP; + /** The BTB. */ DefaultBTB BTB; - ReturnAddrStack RAS; + /** The per-thread return address stack. */ + ReturnAddrStack RAS[Impl::MaxThreads]; + /** Stat for number of BP lookups. */ Stats::Scalar<> lookups; + /** Stat for number of conditional branches predicted. */ Stats::Scalar<> condPredicted; + /** Stat for number of conditional branches predicted incorrectly. */ Stats::Scalar<> condIncorrect; + /** Stat for number of BTB lookups. */ Stats::Scalar<> BTBLookups; + /** Stat for number of BTB hits. */ Stats::Scalar<> BTBHits; + /** Stat for number of times the BTB is correct. */ Stats::Scalar<> BTBCorrect; + /** Stat for number of times the RAS is used to get a target. */ Stats::Scalar<> usedRAS; + /** Stat for number of times the RAS is incorrect. */ Stats::Scalar<> RASIncorrect; }; -#endif // __BPRED_UNIT_HH__ +#endif // __CPU_O3_BPRED_UNIT_HH__ |