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added comments to the "ext_used_syms" function

master
_xeroxz 2 months ago
parent
commit
632f6d66e6
  1. 27
      src/decomp/decomp.cpp

27
src/decomp/decomp.cpp

@ -219,39 +219,62 @@ std::uint32_t decomp_t::next_sym(coff::image_t* img,
}
std::uint32_t decomp_t::ext_used_syms(const std::string&& entry_sym) {
// start with the entry point symbol...
std::optional<sym_data_t> entry = get_symbol(entry_sym.data());
// if the entry point symbol cant be found simply return 0 (for 0 symbols
// extracted)...
if (!entry.has_value())
return 0u;
// little memoization for perf boost... :^)
std::set<coff::symbol_t*> cache;
const auto finding_syms = [&]() -> bool {
// for all the symbols...
for (auto itr = m_used_syms.begin(); itr != m_used_syms.end(); ++itr) {
auto [img, sym, size] = *itr;
// if the symbol has a section and its not already in the cache...
if (sym->has_section() && !cache.count(sym) && size) {
auto scn = img->get_section(sym->section_index - 1);
auto num_relocs = scn->num_relocs;
auto relocs = reinterpret_cast<coff::reloc_t*>(
scn->ptr_relocs + reinterpret_cast<std::uint8_t*>(img));
// see if there are any relocations inside of the symbol...
for (auto idx = 0u; idx < num_relocs; ++idx) {
auto reloc = &relocs[idx];
// if the reloc is inside of the current symbol...
if (reloc->virtual_address >= sym->value &&
reloc->virtual_address < sym->value + size) {
// get the symbol for the relocation and add it to the m_used_symbol
// vector...
auto reloc_sym = img->get_symbol(reloc->symbol_index);
auto sym_name = symbol_t::name(img, reloc_sym);
entry = get_symbol(sym_name);
// if the symbol already exists in the m_used_syms vector then we
// return out of this function and continue looping over all symbols
// recursively...
if (m_used_syms.emplace(entry.value()).second)
return true;
return true; // returns to the for loop below this lambda. the
// return true here means we added yet another
// symbol to the "m_used_syms" vector...
}
}
// cache the symbol so we dont need to process it again...
cache.emplace(sym);
}
}
return false;
return false; // only ever returns false here when every single symbol
// inside of m_used_syms has been looked at to see if all of
// its relocation symbols are included in the m_used_syms
// vector (meaning we got all the used symbols...)
};
// add the entry point symbol...
m_used_syms.emplace(entry.value());
// keep recursively adding symbols until we found them all..
for (m_used_syms.emplace(entry.value()); finding_syms();)
;

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