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-rw-r--r--src/cpu/o3/store_set.hh40
1 files changed, 40 insertions, 0 deletions
diff --git a/src/cpu/o3/store_set.hh b/src/cpu/o3/store_set.hh
index 64255c51a..f5a44a1ac 100644
--- a/src/cpu/o3/store_set.hh
+++ b/src/cpu/o3/store_set.hh
@@ -46,58 +46,98 @@ struct ltseqnum {
}
};
+/**
+ * Implements a store set predictor for determining if memory
+ * instructions are dependent upon each other. See paper "Memory
+ * Dependence Prediction using Store Sets" by Chrysos and Emer. SSID
+ * stands for Store Set ID, SSIT stands for Store Set ID Table, and
+ * LFST is Last Fetched Store Table.
+ */
class StoreSet
{
public:
typedef unsigned SSID;
public:
+ /** Default constructor. init() must be called prior to use. */
StoreSet() { };
+ /** Creates store set predictor with given table sizes. */
StoreSet(int SSIT_size, int LFST_size);
+ /** Default destructor. */
~StoreSet();
+ /** Initializes the store set predictor with the given table sizes. */
void init(int SSIT_size, int LFST_size);
+ /** Records a memory ordering violation between the younger load
+ * and the older store. */
void violation(Addr store_PC, Addr load_PC);
+ /** Inserts a load into the store set predictor. This does nothing but
+ * is included in case other predictors require a similar function.
+ */
void insertLoad(Addr load_PC, InstSeqNum load_seq_num);
+ /** Inserts a store into the store set predictor. Updates the
+ * LFST if the store has a valid SSID. */
void insertStore(Addr store_PC, InstSeqNum store_seq_num,
unsigned tid);
+ /** Checks if the instruction with the given PC is dependent upon
+ * any store. @return Returns the sequence number of the store
+ * instruction this PC is dependent upon. Returns 0 if none.
+ */
InstSeqNum checkInst(Addr PC);
+ /** Records this PC/sequence number as issued. */
void issued(Addr issued_PC, InstSeqNum issued_seq_num, bool is_store);
+ /** Squashes for a specific thread until the given sequence number. */
void squash(InstSeqNum squashed_num, unsigned tid);
+ /** Resets all tables. */
void clear();
+ /** Debug function to dump the contents of the store list. */
+ void dump();
+
private:
+ /** Calculates the index into the SSIT based on the PC. */
inline int calcIndex(Addr PC)
{ return (PC >> offsetBits) & indexMask; }
+ /** Calculates a Store Set ID based on the PC. */
inline SSID calcSSID(Addr PC)
{ return ((PC ^ (PC >> 10)) % LFSTSize); }
+ /** The Store Set ID Table. */
std::vector<SSID> SSIT;
+ /** Bit vector to tell if the SSIT has a valid entry. */
std::vector<bool> validSSIT;
+ /** Last Fetched Store Table. */
std::vector<InstSeqNum> LFST;
+ /** Bit vector to tell if the LFST has a valid entry. */
std::vector<bool> validLFST;
+ /** Map of stores that have been inserted into the store set, but
+ * not yet issued or squashed.
+ */
std::map<InstSeqNum, int, ltseqnum> storeList;
typedef std::map<InstSeqNum, int, ltseqnum>::iterator SeqNumMapIt;
+ /** Store Set ID Table size, in entries. */
int SSITSize;
+ /** Last Fetched Store Table size, in entries. */
int LFSTSize;
+ /** Mask to obtain the index. */
int indexMask;
// HACK: Hardcoded for now.