cpu: Fix bi-mode branch predictor thresholds

[gem5.git] / src / cpu / pred / tournament.hh

diff --git a/src/cpu/pred/tournament.hh b/src/cpu/pred/tournament.hh
index 35cfd8455ae587ab9f025f89b69bc5ee6e3c77ff..c4c09268791583c4637fe510f77cbbe12ed8ac5f 100644 (file)
--- a/src/cpu/pred/tournament.hh
+++ b/src/cpu/pred/tournament.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011 ARM Limited
+ * Copyright (c) 2011, 2014 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -38,40 +38,35 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * Authors: Kevin Lim
+ *          Timothy M. Jones
+ *          Nilay Vaish
  */
 
-#ifndef __CPU_O3_TOURNAMENT_PRED_HH__
-#define __CPU_O3_TOURNAMENT_PRED_HH__
+#ifndef __CPU_PRED_TOURNAMENT_PRED_HH__
+#define __CPU_PRED_TOURNAMENT_PRED_HH__
 
 #include <vector>
 
 #include "base/types.hh"
-#include "cpu/o3/sat_counter.hh"
+#include "cpu/pred/bpred_unit.hh"
+#include "cpu/pred/sat_counter.hh"
+#include "params/TournamentBP.hh"
 
 /**
  * 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.
+ * predictor chooses between the two.  Both the global history register
+ * and the selected local history are speculatively updated.
  */
-class TournamentBP
+class TournamentBP : public BPredUnit
 {
   public:
     /**
      * Default branch predictor constructor.
      */
-    TournamentBP(unsigned localCtrBits,
-                 unsigned localHistoryTableSize,
-                 unsigned localHistoryBits,
-                 unsigned globalPredictorSize,
-                 unsigned globalHistoryBits,
-                 unsigned globalCtrBits,
-                 unsigned choicePredictorSize,
-                 unsigned choiceCtrBits,
-                 unsigned instShiftAmt);
+    TournamentBP(const TournamentBPParams *params);
 
     /**
      * Looks up the given address in the branch predictor and returns
@@ -81,7 +76,7 @@ class TournamentBP
      * @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
@@ -89,7 +84,7 @@ class TournamentBP
      * global history stored in it.
      * @param bp_history Pointer that will be set to the BPHistory object.
      */
-    void uncondBr(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.
@@ -97,7 +92,7 @@ class TournamentBP
      * @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.
@@ -107,17 +102,17 @@ class TournamentBP
      * @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);
 
     /**
      * 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);
 
-    /** Returns the global history. */
-    inline unsigned readGlobalHist() { return globalHistory; }
+    unsigned getGHR(ThreadID tid, void *bp_history) const;
 
   private:
     /**
@@ -134,10 +129,10 @@ class TournamentBP
     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.
@@ -169,6 +164,7 @@ class TournamentBP
         static int newCount;
 #endif
         unsigned globalHistory;
+        unsigned localHistoryIdx;
         unsigned localHistory;
         bool localPredTaken;
         bool globalPredTaken;
@@ -210,7 +206,7 @@ class TournamentBP
     /** 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. */
@@ -237,11 +233,6 @@ class TournamentBP
     /** Number of bits in the choice predictor's counters. */
     unsigned choiceCtrBits;
 
-    /** Number of bits to shift the instruction over to get rid of the word
-     *  offset.
-     */
-    unsigned instShiftAmt;
-
     /** Thresholds for the counter value; above the threshold is taken,
      *  equal to or below the threshold is not taken.
      */
@@ -250,4 +241,4 @@ class TournamentBP
     unsigned choiceThreshold;
 };
 
-#endif // __CPU_O3_TOURNAMENT_PRED_HH__
+#endif // __CPU_PRED_TOURNAMENT_PRED_HH__