optimize_phv.h

 
#ifndef BF_P4C_PHV_OPTIMIZE_PHV_H_
#define BF_P4C_PHV_OPTIMIZE_PHV_H_
 
#include <optional>
 
#include "backends/tofino/bf-p4c/phv/allocate_phv.h"
#include "backends/tofino/bf-p4c/phv/phv_fields.h"
#include "backends/tofino/bf-p4c/phv/utils/utils.h"
 
struct TransactData {
    // Mapping table of Transaction -> SuperCluster
    std::unordered_map<PHV::Transaction *, PHV::SuperCluster *> tr_to_sc_i;
    // Mapping table of Transaction -> Unique Transaction ID
    std::unordered_map<PHV::Transaction *, int> tr_to_tr_id_i;
    // Ordered Mapping table of Unique Transaction ID -> Transaction
    std::map<int, PHV::Transaction *> tr_id_to_tr_i;
    // Ordered Mapping table of Container -> Set of Unique Transaction ID
    std::map<PHV::Container, std::set<int>> container_to_tr_ids_i;
    // Next Transaction ID to use. Removed Transaction ID are never re-used
    int next_tr_id = 0;
 
    // Mapping table of Unique Transaction ID -> Diff for logging purpose
    std::map<int, const cstring> tr_id_to_diff;
};
 
class BruteForceOptimizationStrategy {
    // Limit the number of dependant transactions when trying to replace a transaction.
    static constexpr int MAX_PRUNED_TRANSACTIONS = 16;
    // Limit the number of passes we spend on trying to optimize the solution. One pass is equal
    // to the number of transaction eligible to be replaced.
    static constexpr int MAX_OPT_PASS = 2;
    // Number of passes that try to optimize the solution without any dark spilling. This is to
    // help Table Allocation fitting.
    static constexpr int MAX_OPT_PASS_WO_DARK = 1;
    // Only apply this optimization process if the solution have at least 32 Transactions. This is
    // to avoid trying to optimize the pounding rounds except if that one is huge and have
    // potential to be swapped differently.
    static constexpr int MIN_TR_SIZE = 32;
    // Largest SuperCluster to optimize. If at least one SuperCluster is larger than that, cancel
    // the optimization process since we don't have much chance to find a solution.
    static constexpr size_t MAX_SC_BIT = 64;
    // Maximum number of bits to place through the optimization process.
    static constexpr size_t MAX_TOTAL_SC_BIT = 256;
 
    // Required to call the BruteForceAllocationStrategy allocation services.
    BruteForceAllocationStrategy &alloc_strategy_i;
    const std::list<PHV::ContainerGroup *> &container_groups_i;
    const ScoreContext &score_ctx_i;
 
    // Transaction Data that is continuously updated to increase the solution score.
    TransactData *data;
 
    // Build a sequence of Transaction In/Out if tr_id is removed.
    bool buildSeqWithout(int tr_id, std::list<int> &tr_in, std::list<int> &tr_out);
 
    // Play a sequence on top of a particular Transaction.
    BruteForceOptimizationStrategy playSeq(std::list<int> &tr_in, PHV::Transaction &partial_alloc);
 
 public:
    explicit BruteForceOptimizationStrategy(
        BruteForceAllocationStrategy &alloc_strategy_i,
        const std::list<PHV::ContainerGroup *> &container_groups, const ScoreContext &score_ctx)
        : alloc_strategy_i(alloc_strategy_i),
          container_groups_i(container_groups),
          score_ctx_i(score_ctx) {
        data = new TransactData();
    }
 
    // Insert a Transaction/SuperCluster to the optimization strategy.
    void addTransaction(PHV::Transaction &transaction, PHV::SuperCluster &sc, int tr_id = -1);
 
    // Start the optimization process.
    std::list<PHV::SuperCluster *> optimize(std::list<PHV::SuperCluster *> &unallocated_sc,
                                            PHV::Transaction &rst);
 
    // Print the Container to Transaction Dependencies.
    void printContDependency();
};
 
#endif /* BF_P4C_PHV_OPTIMIZE_PHV_H_ */