convertEnums.h

/*
 * Copyright 2016 VMware, Inc.
 * SPDX-FileCopyrightText: 2016 VMware, Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef MIDEND_CONVERTENUMS_H_
#define MIDEND_CONVERTENUMS_H_
 
#include "frontends/p4/typeChecking/typeChecker.h"
#include "ir/ir.h"
 
namespace P4 {

class ChooseEnumRepresentation {
 public:
    virtual ~ChooseEnumRepresentation() {}
    // If true this type has to be converted.
    virtual bool convert(const IR::Type_Enum *type) const = 0;
    // Returns the value to be assigned to the enum Constant.
    // Maps to the index of member in the enum by default.
    virtual unsigned encoding(const IR::Type_Enum *, unsigned n) const { return n; }
    // enumCount is the number of different enum values.
    // The returned value is the width of Type_Bits used
    // to represent the enum.  Obviously, we must have
    // 2^(return) >= enumCount.
    virtual unsigned enumSize(unsigned enumCount) const = 0;
};
 
class EnumRepresentation {
    string_map<unsigned> repr;
 
 public:
    const IR::Type_Bits *type;
 
    EnumRepresentation(Util::SourceInfo srcInfo, unsigned width) {
        type = IR::Type_Bits::get(srcInfo, width, false);
    }
    void add(cstring decl) { repr.emplace(decl, repr.size()); }
    unsigned get(cstring decl) const { return ::P4::get(repr, decl); }
 
    auto begin() { return repr.begin(); }
    auto begin() const { return repr.begin(); }
    auto end() { return repr.end(); }
    auto end() const { return repr.end(); }
};

class DoConvertEnums : public Transform {
    friend class ConvertEnums;
 
    ordered_map<const IR::Type_Enum *, EnumRepresentation *> repr;
    ChooseEnumRepresentation *policy;
    TypeMap *typeMap;
 
 public:
    DoConvertEnums(ChooseEnumRepresentation *policy, TypeMap *typeMap)
        : policy(policy), typeMap(typeMap) {
        CHECK_NULL(policy);
        CHECK_NULL(typeMap);
        setName("DoConvertEnums");
    }
    const IR::Node *preorder(IR::Type_Enum *type) override;
    const IR::Node *postorder(IR::Type_Name *type) override;
    const IR::Node *postorder(IR::Member *expression) override;
};
 
class ConvertEnums : public PassManager {
    DoConvertEnums *convertEnums{nullptr};
 
 public:
    using EnumMapping = decltype(DoConvertEnums::repr);
    ConvertEnums(TypeMap *typeMap, ChooseEnumRepresentation *policy,
                 TypeChecking *typeChecking = nullptr)
        : convertEnums(new DoConvertEnums(policy, typeMap)) {
        if (!typeChecking) typeChecking = new TypeChecking(nullptr, typeMap);
        passes.push_back(typeChecking);
        passes.push_back(convertEnums);
        passes.push_back(new ClearTypeMap(typeMap));
        setName("ConvertEnums");
    }
 
    EnumMapping getEnumMapping() const { return convertEnums->repr; }
};

class EnumOn32Bits : public P4::ChooseEnumRepresentation {
    bool convert(const IR::Type_Enum *type) const override {
        if (type->srcInfo.isValid()) {
            return true;
        }
        return true;
    }
    unsigned enumSize(unsigned) const override { return 32; }
};
 
}  // namespace P4
 
#endif /* MIDEND_CONVERTENUMS_H_ */