add_initialization.h

 
#ifndef BACKENDS_TOFINO_BF_P4C_PHV_ADD_INITIALIZATION_H_
#define BACKENDS_TOFINO_BF_P4C_PHV_ADD_INITIALIZATION_H_
 
#include "backends/tofino/bf-p4c/common/field_defuse.h"
#include "backends/tofino/bf-p4c/common/map_tables_to_actions.h"
#include "backends/tofino/bf-p4c/mau/add_always_run.h"
#include "backends/tofino/bf-p4c/mau/table_dependency_graph.h"
#include "backends/tofino/bf-p4c/mau/table_mutex.h"
#include "backends/tofino/bf-p4c/phv/analysis/meta_live_range.h"
#include "backends/tofino/bf-p4c/phv/finalize_stage_allocation.h"
#include "backends/tofino/bf-p4c/phv/phv_fields.h"
 
class MapFieldToExpr : public Inspector {
 private:
    const PhvInfo &phv;
    ordered_map<int, const IR::Expression *> fieldExpressions;
 
    profile_t init_apply(const IR::Node *root) override {
        fieldExpressions.clear();
        return Inspector::init_apply(root);
    }
 
    bool preorder(const IR::Expression *expr) override;
 
 public:
    explicit MapFieldToExpr(const PhvInfo &p) : phv(p) {}
 
    const IR::Expression *getExpr(const PHV::Field *field) const {
        BUG_CHECK(fieldExpressions.count(field->id), "Missing IR::Expression mapping of %1%",
                  field->name);
        return fieldExpressions.at(field->id)->clone();
    }
 
    const IR::MAU::Instruction *generateInitInstruction(const PHV::AllocSlice &slice) const;
 
    const IR::MAU::Instruction *generateInitInstruction(const PHV::AllocSlice &dest,
                                                        const PHV::AllocSlice &source) const;
};
 
class ComputeFieldsRequiringInit : public Visitor {
 private:
    const PhvInfo &phv;
 
    // Map of action names to the set of fields that must be initialized at that action.
    ordered_map<const IR::MAU::Action *, std::vector<PHV::AllocSlice>> actionInits;
 
    // Map of all fields that must be initialized (across all actions).
    ordered_set<PHV::FieldSlice> fieldsForInit;
 
    const IR::Node *apply_visitor(const IR::Node *root, const char * = nullptr) override;
 
 public:
    explicit ComputeFieldsRequiringInit(const PhvInfo &p) : phv(p) {}
 
    // @returns the set of all fields that must be initialized across all actions.
    const ordered_set<PHV::FieldSlice> &getSlicesRequiringInitialization() const {
        return fieldsForInit;
    }
 
    // @returns the map of all actions and the metadata fields to be initialized in those actions.
    const ordered_map<const IR::MAU::Action *, std::vector<PHV::AllocSlice>> &getAllActionInits()
        const {
        return actionInits;
    }
 
    // @returns the set of fields that must be initialized at action @act.
    const std::vector<PHV::AllocSlice> getInitsForAction(const IR::MAU::Action *act) const {
        std::vector<PHV::AllocSlice> empty;
        if (!actionInits.count(act)) return empty;
        return actionInits.at(act);
    }
};
 
class ComputeDarkInitialization : public Inspector {
 private:
    PhvInfo &phv;
    const MapTablesToActions &tableActionsMap;
    const MapFieldToExpr &fieldToExpr;
    const DependencyGraph &dg;
 
    ordered_map<cstring, ordered_set<const IR::MAU::Primitive *>> actionToInsertedInsts;
    ordered_map<const PHV::DarkInitEntry, IR::MAU::Table *> darkInitToARA;
 
    void computeInitInstruction(const PHV::AllocSlice &slice, const IR::MAU::Action *act);
 
    // Calculate the minStage for the ARA table moving a slice between
    // normal/dark PHVs
    //  Ths will need to be updated with more detailed analysis when
    //        the initialization injection stops using the dominator analysis
    int calcMinStage(const PHV::AllocSlice &sl_prev, const PHV::AllocSlice &sl_current,
                     int prior_max_stage, int post_min_stage, bool init_from_zero);
 
    // Check dest and src containers if they match with containers in
    // darkInitToARA AllocSlice's
    bool use_same_containers(PHV::AllocSlice alloc_sl, IR::MAU::Table *&ara_tbl);
 
    // Create new MOVE instruction and place it into new Action which
    // is added into new AlwaysRunAction Table. Use prior and post
    // Tables from @alloc_sl to set the minStage for the new AlwaysRunAction Table
    void createAlwaysRunTable(PHV::AllocSlice &alloc_sl);
 
    cstring getKey(const IR::MAU::Table *tbl, const IR::MAU::Action *act) const {
        return (tbl->name + "." + act->name);
    }
 
    profile_t init_apply(const IR::Node *root) override;
    void end_apply() override;
 
 public:
    // Increasing integer value used in AlwaysRunAction Table name
    static int ARA_table_id;
    explicit ComputeDarkInitialization(PhvInfo &p, const MapTablesToActions &m,
                                       const MapFieldToExpr &e, const DependencyGraph &g)
        : phv(p), tableActionsMap(m), fieldToExpr(e), dg(g) {}
 
    const ordered_set<const IR::MAU::Primitive *> getInitializationInstructions(
        const IR::MAU::Table *tbl, const IR::MAU::Action *act) const;
};
 
class ComputeDependencies : public Inspector {
 private:
    using TableExprRanges = FinalizeStageAllocation::TableExprRanges;
    using StageFieldEntry = FinalizeStageAllocation::StageFieldEntry;
    using StageFieldUse = FinalizeStageAllocation::StageFieldUse;
 
    PhvInfo &phv;
    const DependencyGraph &dg;
    const MapTablesToActions &actionsMap;
    const ComputeFieldsRequiringInit &fieldsForInit;
    const FieldDefUse &defuse;
    const MetadataLiveRange &liverange;
    const TablesMutuallyExclusive &tableMutex;
 
    ordered_set<cstring> initTableNames;
 
    profile_t init_apply(const IR::Node *root) override;
    void end_apply() override;
 
    // @fields: Map of a field being initialized to the overlapping fields.
    // @inits: Map of a field being initialized to the tables where the initialization is inserted.
    // Note down all the dependencies that would be induced because of the initialization.
    void noteDependencies(
        const ordered_map<PHV::AllocSlice, ordered_set<PHV::AllocSlice>> &slices,
        const ordered_map<PHV::AllocSlice, ordered_set<const IR::MAU::Table *>> &initNodes);
 
    void addDepsForDarkInitialization();
    void addDepsForSetsOfAllocSlices(const std::vector<PHV::AllocSlice> &alloc_slices,
                                     const StageFieldUse &fieldWrites,
                                     const StageFieldUse &fieldReads, bool checkBitsOverlap = true);
    // Given a @min_stage, a @max_stage, and a map @uses of the uses/defs of slice @alloc,
    // populate @tables with all the tables using that slice between the min and max stage
    // range.
    void accountUses(int min_stage, int max_stage, const PHV::AllocSlice &alloc,
                     const StageFieldUse &uses, ordered_set<const IR::MAU::Table *> &tables) const;
    void summarizeDarkInits(StageFieldUse &fieldWrites, StageFieldUse &fieldReads);
 
 public:
    ComputeDependencies(PhvInfo &p, const DependencyGraph &g, const MapTablesToActions &a,
                        const ComputeFieldsRequiringInit &i, const FieldDefUse &d,
                        const MetadataLiveRange &r, const TablesMutuallyExclusive &m)
        : phv(p), dg(g), actionsMap(a), fieldsForInit(i), defuse(d), liverange(r), tableMutex(m) {}
 
    bool isInitTable(const IR::MAU::Table *tbl) const { return initTableNames.count(tbl->name); }
};
 
class MarkDarkInitTables : public Transform {
    const ComputeDependencies &dep;
 
    IR::Node *preorder(IR::MAU::Table *tbl) override {
        if (dep.isInitTable(tbl)) {
            tbl->has_dark_init = true;
            LOG2("\tDark initialization table: " << tbl->name);
        }
        return tbl;
    }
 
 public:
    explicit MarkDarkInitTables(const ComputeDependencies &d) : dep(d) {}
};
 
class AddSliceInitialization : public PassManager {
 private:
    TablesMutuallyExclusive tableMutex;
    MapTablesToActions actionsMap;
    MapFieldToExpr fieldToExpr;
    ComputeFieldsRequiringInit init;
    ComputeDependencies dep;
    ComputeDarkInitialization computeDarkInit;
 
 public:
    explicit AddSliceInitialization(PhvInfo &p, FieldDefUse &d, const DependencyGraph &g,
                                    const MetadataLiveRange &r);
};
 
#endif /* BACKENDS_TOFINO_BF_P4C_PHV_ADD_INITIALIZATION_H_ */