Method relocate

libraries/asmjit/asmjit/base/codeholder.cpp:563–691

TODO: Support multiple sections, this only relocates the first. TODO: This should go to Runtime as it's responsible for relocating the code, CodeHolder should just hold it.

// TODO: This should go to Runtime as it's responsible for relocating the
//       code, CodeHolder should just hold it.
size_t CodeHolder::relocate(void* _dst, uint64_t baseAddress) const noexcept {
  SectionEntry* section = _sections[0];
  ASMJIT_ASSERT(section != nullptr);

  uint8_t* dst = static_cast<uint8_t*>(_dst);
  if (baseAddress == Globals::kNoBaseAddress)
    baseAddress = static_cast<uint64_t>((uintptr_t)dst);

#if !defined(ASMJIT_DISABLE_LOGGING)
  Logger* logger = getLogger();
#endif // ASMJIT_DISABLE_LOGGING

  size_t minCodeSize = section->getBuffer().getLength(); // Minimum code size.
  size_t maxCodeSize = getCodeSize();                    // Includes all possible trampolines.

  // We will copy the exact size of the generated code. Extra code for trampolines
  // is generated on-the-fly by the relocator (this code doesn't exist at the moment).
  ::memcpy(dst, section->_buffer._data, minCodeSize);

  // Trampoline offset from the beginning of dst/baseAddress.
  size_t trampOffset = minCodeSize;

  // Relocate all recorded locations.
  size_t numRelocs = _relocations.getLength();
  const RelocEntry* const* reArray = _relocations.getData();

  for (size_t i = 0; i < numRelocs; i++) {
    const RelocEntry* re = reArray[i];

    // Possibly deleted or optimized out relocation entry.
    if (re->getType() == RelocEntry::kTypeNone)
      continue;

    uint64_t ptr = re->getData();
    size_t codeOffset = static_cast<size_t>(re->getSourceOffset());

    // Make sure that the `RelocEntry` is correct, we don't want to write
    // out of bounds in `dst`.
    if (ASMJIT_UNLIKELY(codeOffset + re->getSize() > maxCodeSize))
      return DebugUtils::errored(kErrorInvalidRelocEntry);

    // Whether to use trampoline, can be only used if relocation type is `kRelocTrampoline`.
    bool useTrampoline = false;

    switch (re->getType()) {
      case RelocEntry::kTypeAbsToAbs: {
        break;
      }

      case RelocEntry::kTypeRelToAbs: {
        ptr += baseAddress;
        break;
      }

      case RelocEntry::kTypeAbsToRel: {
        ptr -= baseAddress + re->getSourceOffset() + re->getSize();
        break;
      }