Implement a simple GetAddressClass for PECOFF

[sas]

Summary

This function apparently is called only by addresses that are valid.
We mainly need to use the ISA class whenever is needed.

Depends on D39315.

Change by Walter Erquinigo <[e-mail]>

source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.h

bool SetLoadAddress(lldb_private::Target &target, lldb::addr_t value,
                       bool value_is_offset) override;
 
   lldb::ByteOrder GetByteOrder() const override;
 
   bool IsExecutable() const override;
 
   uint32_t GetAddressByteSize() const override;
 
-  //    virtual lldb_private::AddressClass
-  //    GetAddressClass (lldb::addr_t file_addr);
+  lldb::AddressClass GetAddressClass(lldb::addr_t file_addr) override;
 
   lldb_private::Symtab *GetSymtab() override;
 
   bool IsStripped() override;
 
   void CreateSections(lldb_private::SectionList &unified_section_list) override;
 
   void Dump(lldb_private::Stream *s) override;

source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp

Symtab *ObjectFilePECOFF::GetSymtab() {
   return m_symtab_ap.get();
 }
 
 bool ObjectFilePECOFF::IsStripped() {
   // TODO: determine this for COFF
   return false;
 }
 
+lldb::AddressClass ObjectFilePECOFF::GetAddressClass(lldb::addr_t file_addr) {
+  auto address_class = ObjectFile::GetAddressClass(file_addr);
+  // Some addresses (e.g. from trampolines) are marked as eAddressClassUnknown.
+  if (address_class == eAddressClassCode ||
+      address_class == eAddressClassUnknown) {
+    ArchSpec header_arch;
+    GetArchitecture(header_arch);
+    if (header_arch.GetMachine() == llvm::Triple::arm) {
+      // The only PECOFF/ARM target we support, Windows Phone, requires all
+      // user code to be Thumb, so we can always return
+      // eAddressClassCodeAlternateISA.
+      return eAddressClassCodeAlternateISA;
+    }
+  }
+  return address_class;
+}
+
 void ObjectFilePECOFF::CreateSections(SectionList &unified_section_list) {
   if (!m_sections_ap.get()) {
     m_sections_ap.reset(new SectionList());
 
     ModuleSP module_sp(GetModule());
     if (module_sp) {
       std::lock_guard<std::recursive_mutex> guard(module_sp->GetMutex());
       const uint32_t nsects = m_sect_headers.size();