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authorKevin Lim <ktlim@umich.edu>2006-06-04 16:07:54 -0400
committerKevin Lim <ktlim@umich.edu>2006-06-04 16:07:54 -0400
commit984c2a4ff677803ff7687a178f1dceb1f0204c30 (patch)
tree10dc244225a4e29a65a94cc83305a2d18d150526 /src/cpu/o3/tournament_pred.hh
parent3156f601db2728d329d9eff272bfa324ebdb2a0c (diff)
parent8671d927d862cdbdf851e74cd07d131679faa7ed (diff)
downloadgem5-984c2a4ff677803ff7687a178f1dceb1f0204c30.tar.xz
Merge ktlim@zamp:/z/ktlim2/clean/m5-o3
into zamp.eecs.umich.edu:/z/ktlim2/clean/newmem-merge src/cpu/checker/o3_cpu_builder.cc: src/cpu/o3/alpha_cpu.hh: src/cpu/o3/alpha_cpu_impl.hh: src/cpu/o3/alpha_dyn_inst_impl.hh: src/cpu/o3/bpred_unit.cc: src/cpu/o3/commit.hh: src/cpu/o3/fetch_impl.hh: src/cpu/o3/lsq_unit.hh: src/cpu/o3/lsq_unit_impl.hh: src/cpu/o3/thread_state.hh: Hand merge. --HG-- rename : cpu/activity.cc => src/cpu/activity.cc rename : cpu/activity.hh => src/cpu/activity.hh rename : cpu/base_dyn_inst.cc => src/cpu/base_dyn_inst.cc rename : cpu/checker/cpu.hh => src/cpu/checker/cpu.hh rename : cpu/checker/cpu_builder.cc => src/cpu/checker/cpu_builder.cc rename : cpu/checker/exec_context.hh => src/cpu/checker/exec_context.hh rename : cpu/checker/o3_cpu_builder.cc => src/cpu/checker/o3_cpu_builder.cc 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_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/comm.hh => src/cpu/o3/comm.hh 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.hh => src/cpu/o3/cpu.hh rename : cpu/o3/cpu_policy.hh => src/cpu/o3/cpu_policy.hh 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/dep_graph.hh => src/cpu/o3/dep_graph.hh 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/fu_pool.cc => src/cpu/o3/fu_pool.cc rename : cpu/o3/fu_pool.hh => src/cpu/o3/fu_pool.hh 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.hh => src/cpu/o3/inst_queue.hh rename : cpu/o3/inst_queue_impl.hh => src/cpu/o3/inst_queue_impl.hh rename : cpu/o3/lsq.hh => src/cpu/o3/lsq.hh rename : cpu/o3/lsq_unit.hh => src/cpu/o3/lsq_unit.hh rename : cpu/o3/lsq_unit_impl.hh => src/cpu/o3/lsq_unit_impl.hh 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/rename.hh => src/cpu/o3/rename.hh rename : cpu/o3/rename_impl.hh => src/cpu/o3/rename_impl.hh 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/store_set.cc => src/cpu/o3/store_set.cc rename : cpu/o3/store_set.hh => src/cpu/o3/store_set.hh rename : cpu/o3/thread_state.hh => src/cpu/o3/thread_state.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_builder.cc => src/cpu/ozone/cpu_builder.cc rename : cpu/ozone/ozone_impl.hh => src/cpu/ozone/ozone_impl.hh rename : cpu/ozone/simple_impl.hh => src/cpu/ozone/simple_impl.hh rename : cpu/ozone/simple_params.hh => src/cpu/ozone/simple_params.hh rename : python/m5/objects/AlphaFullCPU.py => src/python/m5/objects/AlphaFullCPU.py rename : python/m5/objects/OzoneCPU.py => src/python/m5/objects/OzoneCPU.py extra : convert_revision : b7be30474dd03dd3970e737a9d0489aeb2ead84f
Diffstat (limited to 'src/cpu/o3/tournament_pred.hh')
-rw-r--r--src/cpu/o3/tournament_pred.hh90
1 files changed, 81 insertions, 9 deletions
diff --git a/src/cpu/o3/tournament_pred.hh b/src/cpu/o3/tournament_pred.hh
index e16600090..92402adc6 100644
--- a/src/cpu/o3/tournament_pred.hh
+++ b/src/cpu/o3/tournament_pred.hh
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2004-2005 The Regents of The University of Michigan
+ * Copyright (c) 2004-2006 The Regents of The University of Michigan
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -36,6 +36,15 @@
#include "cpu/o3/sat_counter.hh"
#include <vector>
+/**
+ * Implements a tournament branch predictor, hopefully identical to the one
+ * used in the 21264. It has a local predictor, which uses a local history
+ * table to index into a table of counters, and a global predictor, which
+ * uses a global history to index into a table of counters. A choice
+ * predictor chooses between the two. Only the global history register
+ * is speculatively updated, the rest are updated upon branches committing
+ * or misspeculating.
+ */
class TournamentBP
{
public:
@@ -55,30 +64,95 @@ class TournamentBP
/**
* Looks up the given address in the branch predictor and returns
- * a true/false value as to whether it is taken.
+ * a true/false value as to whether it is taken. Also creates a
+ * BPHistory object to store any state it will need on squash/update.
* @param branch_addr The address of the branch to look up.
+ * @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);
+ bool lookup(Addr &branch_addr, void * &bp_history);
+
+ /**
+ * Records that there was an unconditional branch, and modifies
+ * the bp history to point to an object that has the previous
+ * global history stored in it.
+ * @param bp_history Pointer that will be set to the BPHistory object.
+ */
+ void uncondBr(void * &bp_history);
/**
* Updates the branch predictor with the actual result of a branch.
* @param branch_addr The address of the branch to update.
* @param taken Whether or not the branch was taken.
+ * @param bp_history Pointer to the BPHistory object that was created
+ * when the branch was predicted.
+ */
+ void update(Addr &branch_addr, bool taken, 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 update(Addr &branch_addr, unsigned global_history, bool taken);
+ void squash(void *bp_history);
+ /** Returns the global history. */
inline unsigned readGlobalHist() { return globalHistory; }
private:
-
+ /**
+ * Returns if the branch should be taken or not, given a counter
+ * value.
+ * @param count The counter value.
+ */
inline bool getPrediction(uint8_t &count);
+ /**
+ * Returns the local history index, given a branch address.
+ * @param branch_addr The branch's PC address.
+ */
inline unsigned calcLocHistIdx(Addr &branch_addr);
- inline void updateHistoriesTaken(unsigned local_history_idx);
+ /** Updates global history as taken. */
+ inline void updateGlobalHistTaken();
- inline void updateHistoriesNotTaken(unsigned local_history_idx);
+ /** Updates global history as not taken. */
+ inline void updateGlobalHistNotTaken();
+
+ /**
+ * Updates local histories as taken.
+ * @param local_history_idx The local history table entry that
+ * will be updated.
+ */
+ inline void updateLocalHistTaken(unsigned local_history_idx);
+
+ /**
+ * Updates local histories as not taken.
+ * @param local_history_idx The local history table entry that
+ * will be updated.
+ */
+ inline void updateLocalHistNotTaken(unsigned local_history_idx);
+
+ /**
+ * The branch history information that is created upon predicting
+ * a branch. It will be passed back upon updating and squashing,
+ * when the BP can use this information to update/restore its
+ * state properly.
+ */
+ struct BPHistory {
+#ifdef DEBUG
+ BPHistory()
+ { newCount++; }
+ ~BPHistory()
+ { newCount--; }
+
+ static int newCount;
+#endif
+ unsigned globalHistory;
+ bool localPredTaken;
+ bool globalPredTaken;
+ bool globalUsed;
+ };
/** Local counters. */
std::vector<SatCounter> localCtrs;
@@ -103,7 +177,6 @@ class TournamentBP
/** Mask to get the proper local history. */
unsigned localHistoryMask;
-
/** Array of counters that make up the global predictor. */
std::vector<SatCounter> globalCtrs;
@@ -122,7 +195,6 @@ class TournamentBP
/** Mask to get the proper global history. */
unsigned globalHistoryMask;
-
/** Array of counters that make up the choice predictor. */
std::vector<SatCounter> choiceCtrs;