resolveReferences.h

/*
Copyright 2013-present Barefoot Networks, Inc.
 
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
 
    http://www.apache.org/licenses/LICENSE-2.0
 
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
 
#ifndef COMMON_RESOLVEREFERENCES_RESOLVEREFERENCES_H_
#define COMMON_RESOLVEREFERENCES_RESOLVEREFERENCES_H_
 
#include "absl/container/flat_hash_map.h"
#include "absl/container/inlined_vector.h"
#include "frontends/common/parser_options.h"
#include "ir/ir.h"
#include "ir/pass_manager.h"
#include "lib/cstring.h"
#include "lib/iterator_range.h"
#include "referenceMap.h"
 
namespace P4 {

enum class ResolutionType { Any, Type, TypeVariable };

class ResolutionContext : virtual public Visitor, public DeclarationLookup {
 private:
    // Returns a vector of the decls that exist in the given namespace, and caches the result
    // for future lookups.
    const std::vector<const IR::IDeclaration *> &memoizeDeclarations(
        const IR::INamespace *ns) const;
 
    using DeclsVector = absl::InlinedVector<const IR::IDeclaration *, 2>;
    using NamespaceDeclsByName = absl::flat_hash_map<cstring, DeclsVector, Util::Hash>;
 
    // Returns a mapping from name -> decl for the given namespace, and caches the result for
    // future lookups.
    NamespaceDeclsByName &memoizeDeclsByName(const IR::INamespace *ns) const;
 
    mutable absl::flat_hash_map<const IR::INamespace *, std::vector<const IR::IDeclaration *>,
                                Util::Hash>
        namespaceDecls;
    mutable absl::flat_hash_map<const IR::INamespace *, NamespaceDeclsByName, Util::Hash>
        namespaceDeclNames;
 
 protected:
    // Note that all errors have been merged by the parser into
    // a single error { } namespace.
    std::vector<const IR::IDeclaration *> lookup(const IR::INamespace *ns, const IR::ID &name,
                                                 ResolutionType type) const;
 
    // match kinds exist in their own special namespace, made from all the match_kind
    // declarations in the global scope.  Unlike errors, we don't merge those scopes in
    // the parser, so we have to find them and scan them here.
    std::vector<const IR::IDeclaration *> lookupMatchKind(const IR::ID &name) const;
 
    // P4_14 allows things to be used before their declaration while P4_16 (generally)
    // does not, so we will resolve names to things declared later only when translating
    // from P4_14 or Type_Vars or ParserStates, or after code transforms that may reorder
    // the code.
    bool anyOrder = false;
 
    ResolutionContext();
    explicit ResolutionContext(bool ao) : anyOrder(ao) {}

    const IR::Vector<IR::Argument> *methodArguments(cstring name) const;
 
 public:
    std::vector<const IR::IDeclaration *> resolve(const IR::ID &name, ResolutionType type) const;

    const IR::IDeclaration *resolveUnique(const IR::ID &name, ResolutionType type,
                                          const IR::INamespace * = nullptr) const;

    virtual const IR::IDeclaration *resolvePath(const IR::Path *path, bool isType) const;

    const IR::Type *resolveType(const IR::Type *type) const;
 
    const IR::IDeclaration *getDeclaration(const IR::Path *path,
                                           bool notNull = false) const override;
    const IR::IDeclaration *getDeclaration(const IR::This *, bool notNull = false) const override;

    auto getDeclarations(const IR::INamespace *ns) const {
        auto nsIt = namespaceDecls.find(ns);
        const auto &decls = nsIt != namespaceDecls.end() ? nsIt->second : memoizeDeclarations(ns);
        return Util::iterator_range(decls);
    }

    auto getDeclsByName(const IR::INamespace *ns, cstring name) const {
        auto nsIt = namespaceDeclNames.find(ns);
        const auto &namesToDecls =
            nsIt != namespaceDeclNames.end() ? nsIt->second : memoizeDeclsByName(ns);
 
        auto decls = namesToDecls.find(name);
        if (decls == namesToDecls.end())
            return Util::Enumerator<const IR::IDeclaration *>::emptyEnumerator();
        return Util::enumerate(decls->second);
    }
};

class ResolveReferences : public Inspector, private ResolutionContext {
    ReferenceMap *refMap;

    bool checkShadow;
 
 private:
    const IR::IDeclaration *resolvePath(const IR::Path *path, bool isType) const override;
 
 public:
    explicit ResolveReferences(/* out */ P4::ReferenceMap *refMap, bool checkShadow = false);
 
    Visitor::profile_t init_apply(const IR::Node *node) override;
    void end_apply(const IR::Node *node) override;
 
    bool preorder(const IR::Type_Name *type) override;
    bool preorder(const IR::PathExpression *path) override;
    bool preorder(const IR::KeyElement *path) override;
    bool preorder(const IR::This *pointer) override;
    bool preorder(const IR::Declaration_Instance *decl) override;
 
    bool preorder(const IR::P4Program *t) override;
    void postorder(const IR::P4Program *t) override;
    bool preorder(const IR::P4Control *t) override;
    bool preorder(const IR::P4Parser *t) override;
    bool preorder(const IR::P4Action *t) override;
    bool preorder(const IR::Function *t) override;
    bool preorder(const IR::TableProperties *t) override;
    bool preorder(const IR::Type_Method *t) override;
    bool preorder(const IR::ParserState *t) override;
    bool preorder(const IR::Type_Extern *t) override;
    bool preorder(const IR::Type_ArchBlock *t) override;
    void postorder(const IR::Type_ArchBlock *t) override;
    bool preorder(const IR::Type_StructLike *t) override;
    bool preorder(const IR::BlockStatement *t) override;
 
    bool preorder(const IR::P4Table *table) override;
    bool preorder(const IR::Declaration *d) override {
        refMap->usedName(d->getName().name);
        return true;
    }
    bool preorder(const IR::Type_Declaration *d) override {
        refMap->usedName(d->getName().name);
        return true;
    }
 
    void checkShadowing(const IR::INamespace *ns) const;
};
 
class CheckShadowing : public PassManager {
    ReferenceMap refMap;
 
 public:
    CheckShadowing() {
        refMap.setIsV1(P4CContext::get().options().isv1());
 
        addPasses({new ResolveReferences(&refMap, /* checkShadow */ true)});
        setName("CheckShadowing");
    }
};
 
}  // namespace P4
 
#endif /* COMMON_RESOLVEREFERENCES_RESOLVEREFERENCES_H_ */