[Lldb-commits] [PATCH] D14631: [dwarf] Handle DWARF forms for address other than DW_FORM_GNU_addr_index and DW_FORM_addr.

Greg Clayton via lldb-commits lldb-commits at lists.llvm.org
Fri Nov 13 09:58:55 PST 2015

clayborg requested changes to this revision.
clayborg added a comment.
This revision now requires changes to proceed.

This is not the right fix. Compilers that emit addresses with DW_FORM_data* forms are saying that this address is an offset from the DW_AT_low_pc so this function will not return a valid address, but it will now return an offset. If you have a compiler that is actually emitting addresses incorrectly using DW_FORM_data* when the values are not offsets, the compiler should be fixed.

There are two solutions to this:
1 - modify DWARFFormValue::Address() to return LLDB_INVALID_ADDRESS if the form is not DW_FORM_addr or DW_FORM_GNU_addr_index.
2 - modify DWARFFormValue::Address() to take an lldb::addr_t that is the base address that the DW_FORM_data* would be relative to. This argument could be defaulted:

  DWARFFormValue::Address(lldb::addr_t base_addr = LLDB_INVALID_ADDRESS) const

Then in the code we would do:

  DWARFFormValue::Address(lldb::addr_t base_addr) const
      switch (m_form)
      case DW_FORM_addr:
          return Unsigned();
      case DW_FORM_GNU_addr_index:
          if (m_cu)
              SymbolFileDWARF* symbol_file = m_cu->GetSymbolFileDWARF();
              if (symbol_file)
                  uint32_t index_size = m_cu->GetAddressByteSize();
                  dw_offset_t addr_base = m_cu->GetAddrBase();
                  lldb::offset_t offset = addr_base + m_value.value.uval * index_size;
                  return symbol_file->get_debug_addr_data().GetMaxU64(&offset, index_size);
       case DW_FORM_data1:
       case DW_FORM_data2:
       case DW_FORM_data4:
       case DW_FORM_data8:
       case DW_FORM_sdata:
       case DW_FORM_udata:
           if (base_addr != LLDB_INVALID_ADDRESS)
              return base_addr + Unsigned();



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