Function ProcessDescriptors

system/lib/libunwind/src/Unwind-EHABI.cpp:73–167

};

_Unwind_Reason_Code ProcessDescriptors(
    _Unwind_State state,
    _Unwind_Control_Block* ucbp,
    struct _Unwind_Context* context,
    Descriptor::Format format,
    const char* descriptorStart,
    uint32_t flags) {

  // EHT is inlined in the index using compact form. No descriptors. #5
  if (flags & 0x1)
    return _URC_CONTINUE_UNWIND;

  // TODO: We should check the state here, and determine whether we need to
  // perform phase1 or phase2 unwinding.
  (void)state;

  const char* descriptor = descriptorStart;
  uint32_t descriptorWord;
  getNextWord(descriptor, &descriptorWord);
  while (descriptorWord) {
    // Read descriptor based on # 9.2.
    uint32_t length;
    uint32_t offset;
    switch (format) {
      case Descriptor::LU32:
        descriptor = getNextWord(descriptor, &length);
        descriptor = getNextWord(descriptor, &offset);
        break;
      case Descriptor::LU16:
        descriptor = getNextNibble(descriptor, &length);
        descriptor = getNextNibble(descriptor, &offset);
        break;
      default:
        assert(false);
        return _URC_FAILURE;
    }

    // See # 9.2 table for decoding the kind of descriptor. It's a 2-bit value.
    Descriptor::Kind kind =
        static_cast<Descriptor::Kind>((length & 0x1) | ((offset & 0x1) << 1));

    // Clear off flag from last bit.
    length &= ~1u;
    offset &= ~1u;
    uintptr_t scopeStart = ucbp->pr_cache.fnstart + offset;
    uintptr_t scopeEnd = scopeStart + length;
    uintptr_t pc = _Unwind_GetIP(context);
    bool isInScope = (scopeStart <= pc) && (pc < scopeEnd);

    switch (kind) {
      case Descriptor::CLEANUP: {
        // TODO(ajwong): Handle cleanup descriptors.
        break;
      }
      case Descriptor::FUNC: {
        // TODO(ajwong): Handle function descriptors.
        break;
      }