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authorKevin Lim <ktlim@umich.edu>2006-05-30 14:17:41 -0400
committerKevin Lim <ktlim@umich.edu>2006-05-30 14:17:41 -0400
commit4a5b51b516853c9fcaabc44caacdd7e8e93dc0ef (patch)
tree4b7d92408a2b74a16ae6f7b4167ded00079355ef /src/cpu/o3/bpred_unit.hh
parentd308055afc1ace1f321b76e8a85a9a45165da2ce (diff)
parentf1fab2a4469d6cb2e55ebac15da02f8c1fcb7055 (diff)
downloadgem5-4a5b51b516853c9fcaabc44caacdd7e8e93dc0ef.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.hh161
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 &params);
+ /**
+ * @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__