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author | Kevin Lim <ktlim@umich.edu> | 2005-03-10 15:53:27 -0500 |
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committer | Kevin Lim <ktlim@umich.edu> | 2005-03-10 15:53:27 -0500 |
commit | c12a665c3120b61ed4e09da5d8a52c57406763d5 (patch) | |
tree | b5176be0d526ea24cafcd6f615058651f2b34dfb /cpu/beta_cpu/tournament_pred.hh | |
parent | aa8c9db159422a313f6dfc9a76fd827515b32126 (diff) | |
parent | 51108a8c0a3a42702f49a945f8a4dac776a8d189 (diff) | |
download | gem5-c12a665c3120b61ed4e09da5d8a52c57406763d5.tar.xz |
Merge ktlim@zizzer.eecs.umich.edu:/bk/m5
into zamp.eecs.umich.edu:/z/ktlim2/m5
--HG--
extra : convert_revision : a58535776cf5a3d17f8d9f65144cdf8db54289aa
Diffstat (limited to 'cpu/beta_cpu/tournament_pred.hh')
-rw-r--r-- | cpu/beta_cpu/tournament_pred.hh | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/cpu/beta_cpu/tournament_pred.hh b/cpu/beta_cpu/tournament_pred.hh new file mode 100644 index 000000000..1512abc78 --- /dev/null +++ b/cpu/beta_cpu/tournament_pred.hh @@ -0,0 +1,115 @@ +#ifndef __CPU_BETA_CPU_TOURNAMENT_PRED_HH__ +#define __CPU_BETA_CPU_TOURNAMENT_PRED_HH__ + +// For Addr type. +#include "arch/alpha/isa_traits.hh" +#include "cpu/beta_cpu/sat_counter.hh" + +class TournamentBP +{ + public: + /** + * Default branch predictor constructor. + */ + TournamentBP(unsigned local_predictor_size, + unsigned local_ctr_bits, + unsigned local_history_table_size, + unsigned local_history_bits, + unsigned global_predictor_size, + unsigned global_history_bits, + unsigned global_ctr_bits, + unsigned choice_predictor_size, + unsigned choice_ctr_bits, + unsigned instShiftAmt); + + /** + * Looks up the given address in the branch predictor and returns + * a true/false value as to whether it is taken. + * @param branch_addr The address of the branch to look up. + * @return Whether or not the branch is taken. + */ + bool lookup(Addr &branch_addr); + + /** + * 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. + */ + void update(Addr &branch_addr, unsigned global_history, bool taken); + + inline unsigned readGlobalHist() { return global_history; } + + private: + + inline bool getPrediction(uint8_t &count); + + inline unsigned calcLocHistIdx(Addr &branch_addr); + + inline void updateHistoriesTaken(unsigned local_history_idx); + + inline void updateHistoriesNotTaken(unsigned local_history_idx); + + /** Local counters. */ + SatCounter *local_ctrs; + + /** Size of the local predictor. */ + unsigned local_predictor_size; + + /** Number of bits of the local predictor's counters. */ + unsigned local_ctr_bits; + + /** Array of local history table entries. */ + unsigned *local_history_table; + + /** Size of the local history table. */ + unsigned local_history_table_size; + + /** Number of bits for each entry of the local history table. + * @todo Doesn't this come from the size of the local predictor? + */ + unsigned local_history_bits; + + /** Mask to get the proper local history. */ + unsigned localHistoryMask; + + + /** Array of counters that make up the global predictor. */ + SatCounter *global_ctrs; + + /** Size of the global predictor. */ + unsigned global_predictor_size; + + /** Number of bits of the global predictor's counters. */ + unsigned global_ctr_bits; + + /** Global history register. */ + unsigned global_history; + + /** Number of bits for the global history. */ + unsigned global_history_bits; + + /** Mask to get the proper global history. */ + unsigned globalHistoryMask; + + + /** Array of counters that make up the choice predictor. */ + SatCounter *choice_ctrs; + + /** Size of the choice predictor (identical to the global predictor). */ + unsigned choice_predictor_size; + + /** Number of bits of the choice predictor's counters. */ + unsigned choice_ctr_bits; + + /** Number of bits to shift the instruction over to get rid of the word + * offset. + */ + unsigned instShiftAmt; + + /** Threshold for the counter value; above the threshold is taken, + * equal to or below the threshold is not taken. + */ + unsigned threshold; +}; + +#endif // __CPU_BETA_CPU_TOURNAMENT_PRED_HH__ |