Function lookupSymbol

src/e9tool/e9types.cpp:321–371

* Lookup a symbol from the cache. If no match is found, attempt to find the * optimal coercion to an existing symbol and cache the result. */

 * optimal coercion to an existing symbol and cache the result.
 */
intptr_t lookupSymbol(const ELF *elf, const char *name, TypeSig sig)
{
    Symbols &symbols = elf->symbols;
    if (symbols.size() == 0)
    {
        // Build symbol cache:
        for (const auto &entry: elf->dynsyms)
        {
            const Elf64_Sym *sym = entry.second;
            if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
                continue;
            intptr_t addr = elf->base + (intptr_t)sym->st_value;
            parseSymbol(symbols, entry.first, addr);
        }
    }

    Symbol key(name, sig);
    auto i = symbols.find(key);
    if (i != symbols.end())
    {
        intptr_t addr = i->second;
        if (addr == INTPTR_MIN)
            return addr;        // Missing
        if (addr < 0)
            return -addr;       // Derived
        else
            return addr;        // Original
    }

    // Attempt to find the optimal coercion:
    Symbol min(name, TYPESIG_MIN), max(name, TYPESIG_MAX);
    auto j = symbols.lower_bound(min);
    auto jend = symbols.upper_bound(max);
    long score = LONG_MAX;
    intptr_t addr = INTPTR_MIN;
    for (; j != jend; j++)
    {
        long nscore = coercible(sig, j->first.sig);
        if (nscore < 0)
            continue;       // Not coercible.
        if (j->second != INTPTR_MIN && nscore < score)
        {
            score = nscore;
            addr  = std::abs(j->second);
        }
    }

    // Add result to cache (note: INTPTR_MIN is a valid value):
    insertSymbol(symbols, name, sig, (addr > 0? -addr: addr));
    return addr;
}

/*
 * Print warning for symbol mismatch.