localizeActions.h

/*
 * SPDX-FileCopyrightText: 2013 Barefoot Networks, Inc.
 * Copyright 2013-present Barefoot Networks, Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef FRONTENDS_P4_LOCALIZEACTIONS_H_
#define FRONTENDS_P4_LOCALIZEACTIONS_H_
 
#include "frontends/common/resolveReferences/referenceMap.h"
#include "frontends/common/resolveReferences/resolveReferences.h"
#include "frontends/p4/callGraph.h"
#include "frontends/p4/typeChecking/typeChecker.h"
#include "frontends/p4/unusedDeclarations.h"
#include "ir/ir.h"
#include "lib/ordered_set.h"
 
namespace P4 {
 
class GlobalActionReplacements {
 public:
    // For each control that uses an action and for each each global action
    // we create a replacement.
    std::map<const IR::P4Control *, ordered_map<const IR::P4Action *, const IR::P4Action *> *> repl;
 
    const IR::P4Action *getReplacement(const IR::P4Action *action,
                                       const IR::P4Control *control) const {
        auto map = ::P4::get(repl, control);
        if (map == nullptr) return nullptr;
        if (map->find(action) != map->end()) return (*map)[action];
        return nullptr;
    }
    void addReplacement(const IR::P4Action *action, const IR::P4Control *control,
                        const IR::P4Action *replacement) {
        LOG1("Cloning global " << dbp(action) << " into " << dbp(replacement) << " for "
                               << dbp(control));
        if (repl.find(control) == repl.end())
            repl[control] = new ordered_map<const IR::P4Action *, const IR::P4Action *>();
        (*repl[control])[action] = replacement;
    }
};
 
// Find global (i.e., declared at toplevel) actions and who uses them.
class FindGlobalActionUses : public Inspector, public ResolutionContext {
    MinimalNameGenerator nameGen;
    GlobalActionReplacements *repl;
    std::set<const IR::P4Action *> globalActions;
 
 public:
    explicit FindGlobalActionUses(GlobalActionReplacements *repl) : repl(repl) {
        CHECK_NULL(repl);
        setName("FindGlobalActionUses");
    }
    bool preorder(const IR::PathExpression *path) override;
    bool preorder(const IR::P4Action *action) override;
    profile_t init_apply(const IR::Node *node) override;
};
 
// Global actions are cloned into actions local to the
// control using them.  One action can produce many copies.
class LocalizeActions : public Transform, public ResolutionContext {
    GlobalActionReplacements *repl;
 
 public:
    explicit LocalizeActions(GlobalActionReplacements *repl) : repl(repl) {
        visitDagOnce = false;
        CHECK_NULL(repl);
        setName("LocalizeActions");
    }
    const IR::Node *postorder(IR::P4Control *control) override;
    const IR::Node *postorder(IR::PathExpression *expression) override;
};
 
class ActionReplacement {
 public:
    // For each action and each user the replacement action to use.
    // Node is either a P4Table or MethodCallExpression.
    std::map<const IR::P4Action *, ordered_map<const IR::Node *, const IR::P4Action *> *> toInsert;
    std::map<const IR::PathExpression *, const IR::P4Action *> repl;
    // For each action all replacements to insert
 
    const IR::P4Action *getActionUser(const IR::P4Action *action, const IR::Node *user) {
        if (toInsert.find(action) == toInsert.end()) return nullptr;
        auto map = toInsert[action];
        CHECK_NULL(map);
        if (map->find(user) == map->end()) return nullptr;
        return (*map)[user];
    }
    void createReplacement(const IR::P4Action *original, const IR::Node *user,
                           const IR::P4Action *replacement) {
        auto map = toInsert[original];
        if (map == nullptr) {
            map = new ordered_map<const IR::Node *, const IR::P4Action *>();
            toInsert[original] = map;
        }
        (*map)[user] = replacement;
    }
    // In the specified path replace the original with the replacement
    void setRefReplacement(const IR::PathExpression *path, const IR::P4Action *replacement) {
        LOG1("Adding replacement " << dbp(replacement) << " used by " << dbp(path));
        repl[path] = replacement;
    }
};
 
// Find actions that are invoked in multiple places; create a new
// copy for each invocation and store it in the repl map.  Ignores
// actions that are not in a control.
class FindRepeatedActionUses : public Inspector, public ResolutionContext {
    MinimalNameGenerator nameGen;
    ActionReplacement *repl;
 
 public:
    explicit FindRepeatedActionUses(ActionReplacement *repl) : repl(repl) {
        CHECK_NULL(repl);
        setName("FindRepeatedActionUses");
    }
    bool preorder(const IR::PathExpression *expression) override;
    profile_t init_apply(const IR::Node *node) override;
};
 
// Replicates actions for each different user.
// Should be run after LocalizeActions.
class DuplicateActions : public Transform {
    ActionReplacement *repl;
 
 public:
    explicit DuplicateActions(ActionReplacement *repl) : repl(repl) {
        visitDagOnce = false;
        CHECK_NULL(repl);
        setName("DuplicateActions");
    }
    const IR::Node *postorder(IR::PathExpression *expression) override;
    const IR::Node *postorder(IR::P4Control *control) override;
};
 
// Add a @name annotation on each global action that does not have one
class TagGlobalActions : public Transform {
 public:
    TagGlobalActions() { setName("TagGlobalActions"); }
    const IR::Node *preorder(IR::P4Action *action) override;
    const IR::Node *preorder(IR::P4Parser *parser) override {
        prune();
        return parser;
    }
    const IR::Node *preorder(IR::P4Control *control) override {
        prune();
        return control;
    }
};

class LocalizeAllActions : public PassManager {
    GlobalActionReplacements globalReplacements;
    ActionReplacement localReplacements;
 
 public:
    explicit LocalizeAllActions(const RemoveUnusedPolicy &policy) {
        passes.emplace_back(new TagGlobalActions());
        passes.emplace_back(new PassRepeated{
            new FindGlobalActionUses(&globalReplacements),
            new LocalizeActions(&globalReplacements),
        });
        passes.emplace_back(new FindRepeatedActionUses(&localReplacements));
        passes.emplace_back(new DuplicateActions(&localReplacements));
        passes.emplace_back(new RemoveAllUnusedDeclarations(policy));
        setName("LocalizeAllActions");
    }
};
 
}  // namespace P4
 
#endif /* FRONTENDS_P4_LOCALIZEACTIONS_H_ */