simplifyKey.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_SIMPLIFYKEY_H_
#define MIDEND_SIMPLIFYKEY_H_
 
#include "frontends/common/resolveReferences/resolveReferences.h"
#include "frontends/p4/sideEffects.h"
#include "frontends/p4/typeChecking/typeChecker.h"
#include "ir/ir.h"
 
namespace P4 {
 
class KeyIsSimple {
 public:
    virtual ~KeyIsSimple() {}
    virtual bool isSimple(const IR::Expression *expression, const Visitor::Context *) = 0;
};
 
class IsLikeLeftValue : public KeyIsSimple, public Inspector {
 protected:
    bool simple = false;
 
 public:
    IsLikeLeftValue() { setName("IsLikeLeftValue"); }
 
    void postorder(const IR::Expression *) override {
        // all other expressions are complicated
        simple = false;
    }
    void postorder(const IR::Member *) override {}
    void postorder(const IR::PathExpression *) override {}
    void postorder(const IR::ArrayIndex *) override {}
    profile_t init_apply(const IR::Node *root) override {
        simple = true;
        return Inspector::init_apply(root);
    }
 
    bool isSimple(const IR::Expression *expression, const Visitor::Context *) override {
        (void)expression->apply(*this);
        return simple;
    }
};
 
class IsValid : public KeyIsSimple, public Inspector, public ResolutionContext {
    TypeMap *typeMap;
 
 public:
    explicit IsValid(TypeMap *typeMap) : typeMap(typeMap) { CHECK_NULL(typeMap); }
    bool isSimple(const IR::Expression *expression, const Visitor::Context *ctxt);
};
 
class IsMask : public IsLikeLeftValue {
 public:
    bool isSimple(const IR::Expression *expression, const Visitor::Context *ctxt) {
        if (auto mask = expression->to<IR::BAnd>()) {
            if (mask->right->is<IR::Constant>())
                expression = mask->left;
            else if (mask->left->is<IR::Constant>())
                expression = mask->right;
        }
        return IsLikeLeftValue::isSimple(expression, ctxt);
    }
};
 
class OrPolicy : public KeyIsSimple {
    KeyIsSimple *left;
    KeyIsSimple *right;
 
 public:
    OrPolicy(KeyIsSimple *left, KeyIsSimple *right) : left(left), right(right) {
        CHECK_NULL(left);
        CHECK_NULL(right);
    }
    bool isSimple(const IR::Expression *expression, const Visitor::Context *ctxt) {
        return left->isSimple(expression, ctxt) || right->isSimple(expression, ctxt);
    }
};
 
class DoSimplifyKey : public Transform {
    MinimalNameGenerator nameGen;
    TypeMap *typeMap;
    KeyIsSimple *key_policy;
    std::map<const IR::P4Table *, TableInsertions *> toInsert;
 
 public:
    DoSimplifyKey(TypeMap *typeMap, KeyIsSimple *key_policy)
        : typeMap(typeMap), key_policy(key_policy) {
        CHECK_NULL(typeMap);
        CHECK_NULL(key_policy);
        setName("DoSimplifyKey");
    }
 
    Visitor::profile_t init_apply(const IR::Node *node) override {
        auto rv = Transform::init_apply(node);
        node->apply(nameGen);
 
        return rv;
    }
 
    const IR::Node *doStatement(const IR::Statement *statement, const IR::Expression *expression);
 
    // These should be all kinds of statements that may contain a table apply
    // after the program has been simplified
    const IR::Node *postorder(IR::MethodCallStatement *statement) override {
        return doStatement(statement, statement->methodCall);
    }
    const IR::Node *postorder(IR::IfStatement *statement) override {
        return doStatement(statement, statement->condition);
    }
    const IR::Node *postorder(IR::SwitchStatement *statement) override {
        return doStatement(statement, statement->expression);
    }
    const IR::Node *postorder(IR::AssignmentStatement *statement) override {
        return doStatement(statement, statement->right);
    }
    const IR::Node *postorder(IR::KeyElement *element) override;
    const IR::Node *postorder(IR::P4Table *table) override;
};
 
class SimplifyKey : public PassManager {
 public:
    SimplifyKey(TypeMap *typeMap, KeyIsSimple *key_policy, TypeChecking *typeChecking = nullptr) {
        if (!typeChecking) typeChecking = new TypeChecking(nullptr, typeMap);
        passes.push_back(typeChecking);
        passes.push_back(new DoSimplifyKey(typeMap, key_policy));
        setName("SimplifyKey");
    }
};
 
}  // namespace P4
 
#endif /* MIDEND_SIMPLIFYKEY_H_ */