header_stack.h

 
#ifndef BF_P4C_COMMON_HEADER_STACK_H_
#define BF_P4C_COMMON_HEADER_STACK_H_
 
#include "ir/ir.h"
#include "ir/pass_manager.h"
#include "lib/map.h"
 
using namespace P4;
 
class PhvInfo;

struct CollectHeaderStackInfo : public Modifier {
    CollectHeaderStackInfo();
 
 private:
    Visitor::profile_t init_apply(const IR::Node *root) override;
    void postorder(IR::HeaderStack *stack) override;
    void postorder(IR::MAU::Primitive *primitive) override;
    void postorder(IR::BFN::Pipe *pipe) override;
 
    BFN::HeaderStackInfo *stacks;
};

class ElimUnusedHeaderStackInfo : public PassManager {
    ordered_set<cstring> unused;
 
    // Find unused headers.
    struct Find : public Inspector {
        ElimUnusedHeaderStackInfo &self;
        const BFN::HeaderStackInfo *stacks = nullptr;
        ordered_set<cstring> used;
 
        explicit Find(ElimUnusedHeaderStackInfo &self) : self(self) {}
 
        Visitor::profile_t init_apply(const IR::Node *root) override {
            self.unused.clear();
            used.clear();
            return Inspector::init_apply(root);
        }
 
        bool preorder(const IR::BFN::Pipe *pipe) override {
            BUG_CHECK(pipe->headerStackInfo != nullptr,
                      "Running ElimUnusedHeaderStackInfo without running "
                      "CollectHeaderStackInfo first?");
            stacks = pipe->headerStackInfo;
            return true;
        }
 
        void postorder(const IR::HeaderStack *stack) override;
        void end_apply() override;
    };
 
    // Remove from pipe->headerStackInfo.
    struct Elim : public Modifier {
        ElimUnusedHeaderStackInfo &self;
        explicit Elim(ElimUnusedHeaderStackInfo &self) : self(self) {}
 
        void postorder(IR::BFN::Pipe *pipe) override;
    };
 
 public:
    ElimUnusedHeaderStackInfo() { addPasses({new Find(*this), new Elim(*this)}); }
};
 
namespace BFN {

struct HeaderStackInfo {
    struct Info {
        cstring name;

        bool inThread[2] = {true, true};

        int size = 0;

        int maxpush = 0;

        int maxpop = 0;
    };
 
 private:
    friend struct ::CollectHeaderStackInfo;
    friend class ::ElimUnusedHeaderStackInfo;
    ordered_map<cstring, Info> info;
 
 public:
    auto begin() const -> decltype(Values(info).begin()) { return Values(info).begin(); }
    auto begin() -> decltype(Values(info).begin()) { return Values(info).begin(); }
    auto end() const -> decltype(Values(info).end()) { return Values(info).end(); }
    auto end() -> decltype(Values(info).end()) { return Values(info).end(); }
    auto at(cstring n) const -> decltype(info.at(n)) { return info.at(n); }
    auto at(cstring n) -> decltype(info.at(n)) { return info.at(n); }
    auto count(cstring n) const -> decltype(info.count(n)) { return info.count(n); }
    const Info *get(cstring n) const {
        if (auto it = info.find(n); it != info.end()) return &it->second;
        return nullptr;
    }
};
}  // namespace BFN

class RemovePushInitialization : public Transform {
    IR::Node *preorder(IR::MAU::Action *act) override;
 
 public:
    RemovePushInitialization() {}
};

class ValidToStkvalid : public Transform {
    struct BFN::HeaderStackInfo *stack_info_ = nullptr;
 
    // Populate stack_info_.
    IR::Node *preorder(IR::BFN::Pipe *pipe) override;
 
    // Replace uses of stk[x].$valid with stk.$stkvalid[y:y], where the latter
    // corresponds to the validity bit in $stkvalid of element x of stk.
    IR::Node *postorder(IR::Member *member) override;
 
    // Replace extractions to slices of $stkvalid with equivalent extractions
    // to the entire field.  Eg. extract(stk.$stkvalid, 0x4) instead of
    // extract(stk.$stkvalid[2:2], 0x1).
    //
    // TODO: This is because Brig doesn't currently support extracting
    // constants to field slices in the parser (see BRIG-584).  As a result,
    // this removes the AliasSlice node and hence loses the aliasing
    // information.  However, as parser extracts aren't exposed to the control
    // plane, this should be fine.
    IR::Node *postorder(IR::BFN::Extract *extract) override;
 
 public:
    explicit ValidToStkvalid(PhvInfo &) {}
};
 
#endif /* BF_P4C_COMMON_HEADER_STACK_H_ */