table_summary.h

 
#ifndef BF_P4C_MAU_TABLE_SUMMARY_H_
#define BF_P4C_MAU_TABLE_SUMMARY_H_
 
#include <iostream>
#include <map>
 
#include "backends/tofino/bf-p4c/device.h"
#include "backends/tofino/bf-p4c/mau/mau_visitor.h"
#include "backends/tofino/bf-p4c/mau/resource.h"
#include "backends/tofino/bf-p4c/mau/resource_estimate.h"
#include "backends/tofino/bf-p4c/mau/table_dependency_graph.h"
#include "backends/tofino/bf-p4c/mau/table_layout.h"
 
namespace Logging {
class FileLog;
}
 
using namespace P4;
 
struct PHVTrigger {
    // stopTableReplayFitting is only for alt-phv-alloc, if the heuristics for fixing problematic
    // table during table replay creates impossible phv constraints, fall back to ALT_FINALIZE_TABLE
    struct failure : public Backtrack::trigger {
        ordered_map<cstring, ordered_set<int>> tableAlloc;
        ordered_map<cstring, ordered_set<int>> internalTableAlloc;
        ordered_map<cstring, std::pair<cstring, cstring>> mergedGateways;
        bool metaInitDisable;
        bool ignorePackConflicts;
        bool firstRoundFit;
        bool stopTableReplayFitting;
        explicit failure(ordered_map<cstring, ordered_set<int>> tables,
                         ordered_map<cstring, ordered_set<int>> internalTables,
                         ordered_map<cstring, std::pair<cstring, cstring>> mergedGateways, bool fit,
                         bool pack = false, bool meta = false, bool stop = false)
            : trigger(OTHER),
              tableAlloc(tables),
              internalTableAlloc(internalTables),
              mergedGateways(mergedGateways),
              metaInitDisable(meta),
              ignorePackConflicts(pack),
              firstRoundFit(fit),
              stopTableReplayFitting(stop) {}
 
        DECLARE_TYPEINFO(failure);
    };
};
 
struct RerunTablePlacementTrigger {
    struct failure : public Backtrack::trigger {
        bool ignoreContainerConflicts = false;
        explicit failure(bool ig) : trigger(OTHER), ignoreContainerConflicts(ig) {}
 
        DECLARE_TYPEINFO(failure);
    };
};
 
/************************
 * Table Placement/PHV allocation backtracktracking and retries
 *
 * There are various possible reasons that PHV allocation and/or Table Placement can fail
 * in a way that requires backtracking to redo things and try alternatives to get a working
 * allocation and placement.  We track this with a 'state' in the TableSummary object which
 * tracks what we've tried so far, and will throw an appropriate Backtrack::trigger exception
 * to try something else.
 *
 * If the first attempt at PHV allocation and table placement succeeds, great! we're done.
 * If not, we redo table placement ignoring container conflicts.  After that, we'll redo
 * PHV allocation with flags based on whether the first round fit, the redo fit, and possibly
 * without metadata init.
 *
 * If that redo worked, we're good; otherwise we redo table placement ignoring container
 * conflicts (again) and then redo PHA allocation a third time.
 *
 * Final Placement is a special state we get into after table placement succeeded but needed
 * to allocate more PHV, which requires rerunning PHV then rerunning table placement.
 *
 *  INITIAL ---> NOCC_TRY1 ---> REDO_PHV1 ---> NOCC_TRY2 ---> REDO_PHV2 --> FAILURE
 *    |                             /                             |            ^
 *    \-----------> SUCCESS <------+------------------------------/            |
 *                                  \                                          |
 *                                   FINAL_PLACEMENT---------------------------+
 *
 *
 * In the alternative PHV allocation, AKA table placement first allocation, the workflow is
 * different. ALT_INITIAL does the trivial phv allocation, this phv allocation assumes there are
 * infinite numbers of phv containers. And every fieldslice is allocated to the smallest possible
 * container. And then it runs default table placement. If default table placement fails, it then
 * runs resource based table placement with backtracking. If table placement succeeds, it goes to
 * ALT_FINALIZE_TABLE_SAME_ORDER stage. In this stage, phv allocation has the information about
 * every fieldslice's live range based on previous table placement result. It redoes phv allocation
 * with liverange information. After phv allocation is finished, compiler will try to replay the
 * table placement result from the result round. If table replay fails, it goes to
 * ALT_FINALIZE_TABLE_SAME_ORDER_TABLE_FIXED. This stage finds the problematic table during table
 * replay and tries to fix them by adding pa_container_size pragma. And it can be done iteratively
 * to make table replay progress. After a finite number of attempts, if it still fails, compiler
 * goes to ALT_FINALIZE_TABLE with all added pa_container_size removed. During ALT_FINALIZE_TABLE,
 * it uses resource-based table placement with backtracking.
 *                                ALT_FINALIZE_TABLE_SAME_ORDER_TABLE_FIXED ------------------
 *                                              ^              |                     |       |
 *                                              |              |                     |       |
 *                  SUCCESS                     |              V                     V       |
 * ALT_INITIAL --------------------->  ALT_FINALIZE_TABLE_SAME_ORDER ------------> SUCCESS   |
 * (Trivial alloc)            ^   (with order suggested by previous round)                   |
 * ( + Default TP)            |                          |                                   |
 *    |                       |                          |                                   |
 *    |                       |                      (FAILURE) <------------------------------
 * (FAILURE)              (SUCCESS)                      |
 *    |                       |                          V
 *    |                       |                   ALT_FINALIZE_TABLE --> SUCCESS / FAILURE
 *    .------------> ALT_RETRY_ENHANCED_TP        ( Default TP
 *                   (Default TP + backtracki      + backtracking
 *                     ( + resource-based)         + resource-based)
 *                            |
 *                            |
 *                            .--> Go back to ALT_INITIAL and use physical stage instead of
 *                                 minstage in the smart packer. If that still end up in this
 *                                 state after that -> FAILURE
 *
 ******************************************************************************************/
// move the compilation state out of table summary
namespace State {
enum state_t {
    INITIAL,
    NOCC_TRY1,
    REDO_PHV1,
    NOCC_TRY2,
    REDO_PHV2,
    FINAL_PLACEMENT,
    FAILURE,
    SUCCESS,
    ALT_INITIAL,
    ALT_RETRY_ENHANCED_TP,
    ALT_FINALIZE_TABLE_SAME_ORDER,
    ALT_FINALIZE_TABLE_SAME_ORDER_TABLE_FIXED,
    ALT_FINALIZE_TABLE,
    FINAL,  // always keep as last state for bounds checking
};
}
 
class TableSummary : public MauInspector {
 public:
    static constexpr int NUM_LOGICAL_TABLES_PER_STAGE = 16;
    static constexpr int FIRST_ALT_RETRY_ENHANCED_TP_INVOCATION = 2;
 
    // This struct represents a placed table and its relevant info as necessary
    // for future table placement / phv allocation rounds. It can / should be
    // extended to add more info as required
    // TBD: Some of the info overlaps with other maps which should be eventually
    // depecrated to use the consolidated struct below
    struct PlacedTable {
        cstring tableName;
        cstring internalTableName;
        cstring gatewayName;
        cstring gatewayMergeCond;
 
        unsigned logicalId;
 
        int stage = -1;
        int min_stage = -1;
        int max_stage = -1;
        int entries = -1;
        int entries_req = -1;
        int srams = -1;
        int tcams = -1;
        int maprams = -1;
        int ways = -1;
        int key_size = -1;
 
        bool gateway_only = false;
 
        LayoutOption layout;
 
        ordered_map<cstring, int> attached_entries;
 
        PlacedTable(const IR::MAU::Table *t, State::state_t state, const DependencyGraph &dg);
        void add(const IR::MAU::Table *t, State::state_t state);
    };
    friend std::ostream &operator<<(std::ostream &out, const PlacedTable &pl);
    typedef enum {
        SUCC,
        FAIL_ON_ADB,    // failure due to action data bus allocation
        FAIL_ON_MEM,    // failure due to memory allocation
        FAIL_ON_IXBAR,  // failure due to input xbar allocation
        FAIL            // other failures
    } PlacementResult;
    friend std::ostream &operator<<(std::ostream &out, PlacementResult result) {
        if (result == SUCC)
            out << "SUCC";
        else if (result == FAIL)
            out << "FAIL";
        else if (result == FAIL_ON_ADB)
            out << "FAIL_ON_ADB";
        else if (result == FAIL_ON_MEM)
            out << "FAIL_ON_MEM";
        else
            out << "FAIL_ON_IXBAR";
        return out;
    }
 
 private:
    static constexpr int CRITICAL_PATH_THRESHOLD = 2;
    static constexpr int ALT_PHV_ALLOC_TABLE_FIX_THRESHOLD = 3;
    int numInvoked = 0;
    bool firstRoundFit = false;
    Logging::FileLog *tsLog = nullptr;
    // Save the previous state in case we have to rollback to this one.
    State::state_t prev_state = State::INITIAL;
    int maxStage = -1;
    int max_stages[3];
    bool ingressDone = false;
    bool egressDone = false;
    // error messages to output if we can't backtrack, stored in an ordered_map to suppress
    // duplicates.  Flag is true if the error should be output as an error and false if it
    // should just be a warning
    ordered_map<cstring, bool> tablePlacementErrors;
    bool no_errors_before_summary = true;
 
    int alt_phv_alloc_table_fixed = 0;
 
    int pipe_id;
    const DependencyGraph &deps;
    const PhvInfo &phv;
    State::state_t &state;
 
    ordered_map<cstring, ordered_set<int>> tableAlloc;
    ordered_map<cstring, ordered_set<int>> internalTableAlloc;
    ordered_map<cstring, std::pair<cstring, cstring>> mergedGateways;
    ordered_map<cstring, cstring> tableNames;
    ordered_map<cstring, cstring> tableINames;
    static ordered_map<cstring, std::set<const IR::MAU::Table *>> tblName2IRptr;
 
    // Map of Global ID (Stage + Logical Id) -> Placed Table
    std::map<int, PlacedTable *> placedTables;
 
    // alt-phv-alloc ONLY
    // trivial_tableAlloc, trivial_internalTableAlloc, trivial_mergedGateways and
    // trival_placedTables are copies of tableAlloc, internalTableAlloc, mergedGateways and
    // placedTables of table placement after trivial phv allocation. We save this information, so
    // that if the heuristic for fixing problematic tables during table replay does not work, we can
    // rollback to this checkpoint and table placement will go to ALT_FINALIZE_TABLE as normal.
    ordered_map<cstring, ordered_set<int>> trivial_tableAlloc;
    ordered_map<cstring, ordered_set<int>> trivial_internalTableAlloc;
    ordered_map<cstring, std::pair<cstring, cstring>> trivial_mergedGateways;
    std::map<int, PlacedTable *> trivial_placedTables;
    // number of sram blocks allocated per table per stage in first round of table placement
    ordered_map<int, ordered_map<cstring, int>> trivial_table_sram_alloc;
 
    PlacementResult table_replay_result = FAIL;
 
    ordered_map<int, const IR::MAU::Table *> trivial_table_info;
    // Map of Global ID -> Table
    std::map<int, const IR::MAU::Table *> order;
    // Map of Stage -> All Tables in stage
    std::map<int, std::set<const IR::MAU::Table *>> tables;
    // Map of Field Name -> Map of Field Slice -> Map of Stage -> No. of IXBar
    // Bytes
    // E.g.
    // { hdr.ipv4.dstAddr, {
    //      { (0:31), {   // For Slice 0..31
    //          { 1, 4 }, // Stage 1 has 4 bytes
    //          { 2, 4 }  // Stage 2 has 4 bytes
    //        }
    //      }, { (32:47), { // For Slice 32..47
    //          { 1, 2 },   // Stage 1 has 2 bytes
    //          { 2, 4 }    // Stage 2 has 4 bytes
    //         }
    //      }
    //   ...
    //  }
    std::map<cstring, std::map<le_bitrange, std::map<int, int>>> ixbarBytes;
    // For ixbar/memory/action_data_bus/imems:  Tofino 1/2 share the pipe between
    // ingress and egress, so every will be in the [0] element of these arrays.
    // Array of Map of Stage -> Input Xbar
    std::map<int, std::unique_ptr<IXBar>> ixbar[2];
    // Map of Stage -> Memories
    std::map<int, std::unique_ptr<Memories>> memory[2];
    // Map of Stage -> ActionDataBus
    std::map<int, std::unique_ptr<ActionDataBus>> action_data_bus[2];
    // Map of Stage -> InstructionMemory
    std::map<int, std::unique_ptr<InstructionMemory>> imems[2];
    // Map of Table Name -> logical id
    std::map<cstring, unsigned> logical_ids;
 
    StageUseEstimate allStages;
 
    // this is only used for alt-phv-alloc, it is a set of table candidates that can be the table
    // to fix so that table replay can progress.
    ordered_set<const IR::MAU::Table *> table_replay_fix_candidates;
    const IR::MAU::Table *table_replay_problematic_table = nullptr;
 
    profile_t init_apply(const IR::Node *root) override;
    bool preorder(const IR::MAU::Table *t) override;
    void postorder(const IR::BFN::Pipe *pipe) override;
    void end_apply() override;
 
    void printTablePlacement();
 
    void generateIxbarBytesInfo();
 
    // This function finds the problematic table during table replay. If table replay failed, it
    // returns three different failure reason FAIL_ON_ADB, FAIL_ON_IXBAR and FAIL_ON_MEM. For
    // different reasons, this function has different heuristics to select the problematic table.
    bool find_problematic_table();
 
    ordered_map<int, ordered_map<cstring, int>> collect_table_sram_alloc_info();
 
 public:
    explicit TableSummary(int pipe_id, const DependencyGraph &dg, const PhvInfo &phv,
                          State::state_t &state);
 
    static cstring getTableIName(const IR::MAU::Table *tbl);
 
    static cstring getTableName(const IR::MAU::Table *tbl);
 
    static void clearTblName2IRptr() { TableSummary::tblName2IRptr.clear(); }
 
    static std::set<const IR::MAU::Table *> getTablePtr(const cstring t_name);
 
    static void addTablePtr(const IR::MAU::Table *ptr);
 
    const ordered_set<int> stages(const IR::MAU::Table *tbl, bool internal = false) const;
 
    int maxStages() const { return maxStage; }
    int maxStages(gress_t gress) const { return max_stages[gress]; }
 
    const ordered_map<cstring, ordered_set<int>> &getTableAlloc(void) const { return tableAlloc; }
 
    // only called by TablePlacement
    void addPlacementError(cstring msg) { tablePlacementErrors[msg] = true; }
    void addPlacementWarnError(cstring msg) { tablePlacementErrors[msg] |= false; }
    void clearPlacementErrors() { tablePlacementErrors.clear(); }
    int placementErrorCount() { return tablePlacementErrors.size(); }
    void FinalizePlacement();
    const ordered_map<cstring, bool> &getPlacementError() { return tablePlacementErrors; }
    void setPlacementError(const ordered_map<cstring, bool> &tpe) { tablePlacementErrors = tpe; }
    void resetPlacement();
    State::state_t getActualState() const { return state; }
    void setPrevState() { state = prev_state; }
    cstring getActualStateStr() const;
    void setAllStagesResources(const StageUseEstimate &use) { allStages = use; }
    StageUseEstimate getAllStagesResources() const { return allStages; }
 
    std::map<int, PlacedTable *> &getPlacedTables() { return placedTables; }
 
    const IR::MAU::Table *get_table_replay_problematic_table() const {
        return table_replay_problematic_table;
    }
    int getNumInvoked() const { return numInvoked; }
 
    // Returns a map of stage and bytes used on ixbar in that stage
    // e.g. field f1 -
    // Stage 1     -> 2 bytes (Normal)
    // Stage 2 - 3 -> 1 byte  (Dark)
    // Stage 4     -> 3 byte  (Normal)
    // Map : {
    // --------------------------
    // Stage | No. of Ixbar Bytes
    // --------------------------
    //  1    |       2
    //  2    |       1
    //  3    |       1
    //  4    |       3
    // --------------------------
    // }
    std::map<int, int> findBytesOnIxbar(const PHV::FieldSlice &slice) const;
    cstring ixbarUsagesStr(const PhvInfo *phv = nullptr) const;
    void printPlacedTables() const;
    void set_table_replay_result(PlacementResult result) { table_replay_result = result; }
 
    PlacementResult get_table_replay_result() const { return table_replay_result; }
 
    friend std::ostream &operator<<(std::ostream &out, const TableSummary &ts);
    friend std::ostream &operator<<(std::ostream &out,
                                    ordered_map<int, const IR::MAU::Table *> &order);
    // this is only for alt-phv-alloc, if progressing table replay is impossible due to adding
    // phv constraints, stop it and backtrack with stopTableReplayFitting = true.
    void stop_table_replay_fitting() const {
        BUG_CHECK(state == State::ALT_FINALIZE_TABLE_SAME_ORDER_TABLE_FIXED,
                  "state is not intened for table replay fitting");
        throw PHVTrigger::failure(trivial_tableAlloc, trivial_internalTableAlloc,
                                  trivial_mergedGateways, firstRoundFit, false, false, true);
    }
    // this is only for alt-phv-alloc, some table summary info need to be cleared before going
    // through phv allocation and table allocation in ALT_FINALIZE_TABLE.
    void clear_table_alloc_info() {
        tableAlloc.clear();
        internalTableAlloc.clear();
        placedTables.clear();
    }
 
    bool is_table_replay() {
        return state == State::ALT_FINALIZE_TABLE_SAME_ORDER ||
               state == State::ALT_FINALIZE_TABLE_SAME_ORDER_TABLE_FIXED;
    }
};
 
#endif /* BF_P4C_MAU_TABLE_SUMMARY_H_ */