expr_uses.h

/*
 * Copyright 2013-present Barefoot Networks, Inc.
 * SPDX-FileCopyrightText: 2013 Barefoot Networks, Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef MIDEND_EXPR_USES_H_
#define MIDEND_EXPR_USES_H_
 
#include "ir/ir.h"
 
namespace P4 {
 
/* Should this be a method on IR::Expression? */

class exprUses : public Inspector {
    cstring look_for;
    const char *search_tail = nullptr;  // pointer into look_for for partial match
    bool result = false;
    bool preorder(const IR::Path *p) override {
        if (look_for.startsWith(p->name.name)) {
            search_tail = look_for.c_str() + p->name.name.size();
            if (*search_tail == 0 || *search_tail == '.' || *search_tail == '[') result = true;
        }
        return !result;
    }
    bool preorder(const IR::Primitive *p) override {
        if (p->name == look_for) result = true;
        return !result;
    }
    bool preorder(const IR::Expression *) override { return !result; }
 
    void postorder(const IR::Member *m) override {
        if (result && search_tail && *search_tail) {
            if (*search_tail == '.') search_tail++;
            if (cstring(search_tail).startsWith(m->member.name)) {
                search_tail += m->member.name.size();
                if (*search_tail == 0 || *search_tail == '.' || *search_tail == '[') return;
            }
            search_tail = nullptr;
            if (!m->expr->type->is<IR::Type_HeaderUnion>()) {
                result = false;
            }
        }
    }
    void postorder(const IR::ArrayIndex *m) override {
        if (result && search_tail && *search_tail) {
            if (*search_tail == '.' || *search_tail == '[') search_tail++;
            if (isdigit(*search_tail)) {
                int idx = strtol(search_tail, const_cast<char **>(&search_tail), 10);
                if (*search_tail == ']') search_tail++;
                if (auto k = m->right->to<IR::Constant>()) {
                    if (k->asInt() == idx) return;
                } else {
                    return;
                }
            }
            result = false;
            search_tail = nullptr;
        }
    }
    void postorder(const IR::PathExpression *) override {}
    void postorder(const IR::Expression *) override { search_tail = nullptr; }
 
 public:
    exprUses(const IR::Expression *e, cstring n) : look_for(n) {
        visitDagOnce = false;
        e->apply(*this);
    }
    explicit operator bool() const { return result; }
};
 
}  // namespace P4
 
#endif /* MIDEND_EXPR_USES_H_ */