diff options
Diffstat (limited to 'cpu/o3/2bit_local_pred.hh')
| -rw-r--r-- | cpu/o3/2bit_local_pred.hh | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/cpu/o3/2bit_local_pred.hh b/cpu/o3/2bit_local_pred.hh index cd65978ca..02595702b 100644 --- a/cpu/o3/2bit_local_pred.hh +++ b/cpu/o3/2bit_local_pred.hh @@ -35,7 +35,14 @@ #include <vector> -class DefaultBP +/** + * Implements a local predictor that uses the PC to index into a table of + * counters. Note that any time a pointer to the bp_history is given, it + * should be NULL using this predictor because it does not have any branch + * predictor state that needs to be recorded or updated; the update can be + * determined solely by the branch being taken or not taken. + */ +class LocalBP { public: /** @@ -44,28 +51,31 @@ class DefaultBP * @param localCtrBits Number of bits per counter. * @param instShiftAmt Offset amount for instructions to ignore alignment. */ - DefaultBP(unsigned localPredictorSize, unsigned localCtrBits, - unsigned instShiftAmt); + LocalBP(unsigned localPredictorSize, unsigned localCtrBits, + 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. + * @param bp_history Pointer to any bp history state. * @return Whether or not the branch is taken. */ - bool lookup(Addr &branch_addr); + bool lookup(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. * @param taken Whether or not the branch was taken. */ - void update(Addr &branch_addr, bool taken); + void update(Addr &branch_addr, bool taken, void *bp_history); + + void squash(void *bp_history) + { assert(bp_history == NULL); } void reset(); private: - /** * Returns the taken/not taken prediction given the value of the * counter. |