specializeGenericTypes.h

/*
Copyright 2020 VMware, 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 FRONTENDS_P4_SPECIALIZEGENERICTYPES_H_
#define FRONTENDS_P4_SPECIALIZEGENERICTYPES_H_
 
#include "frontends/common/resolveReferences/referenceMap.h"
#include "frontends/p4/typeChecking/typeChecker.h"
#include "ir/ir.h"
 
namespace P4 {
 
struct TypeSpecialization : public IHasDbPrint {
    cstring name;
    const IR::Type_Specialized *specialized;
    const IR::Type_Declaration *declaration;
    const IR::Type_StructLike *replacement;
    const IR::Node *insertion;
    const IR::Vector<IR::Type> *argumentTypes;
 
    TypeSpecialization(cstring name, const IR::Type_Specialized *specialized,
                       const IR::Type_Declaration *decl, const IR::Node *insertion,
                       const IR::Vector<IR::Type> *argTypes)
        : name(name),
          specialized(specialized),
          declaration(decl),
          replacement(nullptr),
          insertion(insertion),
          argumentTypes(argTypes) {
        CHECK_NULL(specialized);
        CHECK_NULL(decl);
        CHECK_NULL(insertion);
        CHECK_NULL(argTypes);
    }
    void dbprint(std::ostream &out) const override {
        out << "Specializing:" << dbp(specialized) << " from " << dbp(declaration) << " as "
            << dbp(replacement) << " inserted at " << dbp(insertion);
    }
};
 
struct TypeSpecializationMap : public IHasDbPrint {
    TypeMap *typeMap;
    // The map can have multiple keys pointing to the same value
    ordered_map<const IR::Type_Specialized *, TypeSpecialization *> map;
    // Keep track of the values in the above map which are already
    // inserted in the program.
    std::set<TypeSpecialization *> inserted;
 
    void add(const IR::Type_Specialized *t, const IR::Type_StructLike *decl,
             const IR::Node *insertion, NameGenerator *nameGen);
    TypeSpecialization *get(const IR::Type_Specialized *t) const;
    bool same(const TypeSpecialization *left, const IR::Type_Specialized *right) const;
    void dbprint(std::ostream &out) const override {
        for (auto it : map) {
            out << dbp(it.first) << " => " << it.second << std::endl;
        }
    }
    IR::Vector<IR::Node> *getSpecializations(const IR::Node *insertionPoint) {
        IR::Vector<IR::Node> *result = nullptr;
        for (auto s : map) {
            if (inserted.find(s.second) != inserted.end()) continue;
            if (s.second->insertion == insertionPoint) {
                if (result == nullptr) result = new IR::Vector<IR::Node>();
                LOG2("Will insert " << dbp(s.second->replacement) << " before "
                                    << dbp(insertionPoint));
                result->push_back(s.second->replacement);
                inserted.emplace(s.second);
            }
        }
        return result;
    }
};

class FindTypeSpecializations : public Inspector {
    TypeSpecializationMap *specMap;
    MinimalNameGenerator nameGen;
 
 public:
    explicit FindTypeSpecializations(TypeSpecializationMap *specMap) : specMap(specMap) {
        CHECK_NULL(specMap);
        setName("FindTypeSpecializations");
    }
 
    void postorder(const IR::Type_Specialized *type) override;
    profile_t init_apply(const IR::Node *node) override;
};

class CreateSpecializedTypes : public Transform {
    TypeSpecializationMap *specMap;
 
 public:
    explicit CreateSpecializedTypes(TypeSpecializationMap *specMap) : specMap(specMap) {
        CHECK_NULL(specMap);
        setName("CreateSpecializedTypes");
    }
 
    const IR::Node *insert(const IR::Node *before);
    const IR::Node *postorder(IR::Type_Declaration *type) override;
    const IR::Node *postorder(IR::Declaration *decl) override { return insert(decl); }
};

class ReplaceTypeUses : public Transform {
    TypeSpecializationMap *specMap;
 
 public:
    explicit ReplaceTypeUses(TypeSpecializationMap *specMap) : specMap(specMap) {
        setName("ReplaceTypeUses");
        CHECK_NULL(specMap);
    }
    const IR::Node *postorder(IR::Type_Specialized *type) override;
    const IR::Node *postorder(IR::StructExpression *expresison) override;
};

class SpecializeGenericTypes : public PassRepeated {
    TypeSpecializationMap specMap;
 
 public:
    explicit SpecializeGenericTypes(TypeMap *typeMap) {
        passes.emplace_back(new PassRepeated({
            new TypeChecking(nullptr, typeMap),
            new FindTypeSpecializations(&specMap),
            new CreateSpecializedTypes(&specMap),
            // The previous pass has mutated some struct types
            new ClearTypeMap(typeMap, true),
        }));
        passes.emplace_back(new TypeChecking(nullptr, typeMap));
        passes.emplace_back(new ReplaceTypeUses(&specMap));
        // The previous pass has invalidated the types of struct expressions
        passes.emplace_back(new ClearTypeMap(typeMap, true));
        specMap.typeMap = typeMap;
        setName("SpecializeGenericTypes");
        setStopOnError(true);
    }
};

//  Note: this pass is currently not used, but some
//  back-ends may find it useful.
class RemoveGenericTypes : public Transform {
 public:
    const IR::Node *postorder(IR::Type_StructLike *type) override {
        if (!type->typeParameters->empty()) return nullptr;
        return type;
    }
    const IR::Node *postorder(IR::Type_Stack *type) override {
        if (type->elementType->is<IR::Type_Specialized>()) return nullptr;
        return type;
    }
};
 
}  // namespace P4
 
#endif /* FRONTENDS_P4_SPECIALIZEGENERICTYPES_H_ */