expandLookahead.h

/*
Copyright 2016 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 MIDEND_EXPANDLOOKAHEAD_H_
#define MIDEND_EXPANDLOOKAHEAD_H_
 
#include "frontends/common/resolveReferences/resolveReferences.h"
#include "frontends/p4/typeChecking/typeChecker.h"
#include "frontends/p4/typeMap.h"
#include "ir/ir.h"
 
namespace P4 {
 
class DoExpandLookahead : public Transform, public ResolutionContext {
    MinimalNameGenerator nameGen;
    P4::TypeMap *typeMap;
    IR::IndexedVector<IR::Declaration> newDecls;
    bool expandHeader = true;
 
    struct ExpansionInfo {
        const IR::Statement *statement;
        unsigned width;
        const IR::Type *origType;
        const IR::PathExpression *tmp;  // temporary used for result
    };
 
    void expand(const IR::PathExpression *bitvector, const IR::Type *type, unsigned *offset,
                const IR::Expression *destination, IR::IndexedVector<IR::StatOrDecl> *output);
    ExpansionInfo *convertLookahead(const IR::MethodCallExpression *expression);
 
 public:
    explicit DoExpandLookahead(TypeMap *typeMap, bool expandHeader = true)
        : typeMap(typeMap), expandHeader(expandHeader) {
        CHECK_NULL(typeMap);
        setName("DoExpandLookahead");
    }
    Visitor::profile_t init_apply(const IR::Node *node) override {
        auto rv = Transform::init_apply(node);
        node->apply(nameGen);
 
        return rv;
    }
 
    const IR::Node *postorder(IR::AssignmentStatement *statement) override;
    const IR::Node *postorder(IR::MethodCallStatement *statement) override;
    const IR::Node *preorder(IR::P4Control *control) override {
        prune();
        return control;
    }
    const IR::Node *preorder(IR::P4Parser *parser) override {
        newDecls.clear();
        return parser;
    }
    const IR::Node *postorder(IR::P4Parser *parser) override {
        if (!newDecls.empty()) parser->parserLocals.append(newDecls);
        return parser;
    }
};
 
class ExpandLookahead : public PassManager {
 public:
    explicit ExpandLookahead(TypeMap *typeMap, TypeChecking *typeChecking = nullptr,
                             bool expandHeader = true) {
        if (!typeChecking) typeChecking = new TypeChecking(nullptr, typeMap);
        passes.push_back(typeChecking);
        passes.push_back(new DoExpandLookahead(typeMap, expandHeader));
        setName("ExpandLookahead");
    }
};
 
}  // namespace P4
 
#endif /* MIDEND_EXPANDLOOKAHEAD_H_ */