[lldb] Add support for recognizing swift ast sections in object files

[bulbazord]

Summary

In Apple's downstream fork, there is support for understanding the swift
AST sections in various binaries. Even though the lldb on llvm.org does
not have support for debugging swift, I think it makes sense to move
support for recognizing swift ast sections upstream.

[kastiglione]

lldb/source/Core/Section.cpp

153

I wonder if this should be "swiftmodules". I have never seen it spelled with a hyphen.

[compnerd]

LGTM with @kastiglione's comments addressed.

lldb/source/Core/Section.cpp

153

Is it actually more than one module? If not, swift-module would make sense given the DWARF cases - it is a "Swift Module" converted to lower kebab case.

[bulbazord]

lldb/source/Core/Section.cpp

153

I added a hyphen to match the previous section types, but I'm not tied to the naming scheme.
I don't know if there is more than one module, but the enum case is plural so I made the string plural too.

[bulbazord]

It seems like there is consensus for actually implementing this functionality but that there were some questions about the actual string. I hope everyone finds my reasoning understandable. If nobody has a strong objection to the actual string, I will land this tomorrow morning or afternoon.

lldb/include/lldb/lldb-enumerations.h

enum SectionType {
   eSectionTypeDWARFDebugStrDwo,
   eSectionTypeDWARFDebugStrOffsetsDwo,
   eSectionTypeDWARFDebugTypesDwo,
   eSectionTypeDWARFDebugRngListsDwo,
   eSectionTypeDWARFDebugLocDwo,
   eSectionTypeDWARFDebugLocListsDwo,
   eSectionTypeDWARFDebugTuIndex,
   eSectionTypeCTF,
+  eSectionTypeSwiftModules,
 };
 
 FLAGS_ENUM(EmulateInstructionOptions){
     eEmulateInstructionOptionNone = (0u),
     eEmulateInstructionOptionAutoAdvancePC = (1u << 0),
     eEmulateInstructionOptionIgnoreConditions = (1u << 1)};
 
 FLAGS_ENUM(FunctionNameType){

lldb/source/Core/Section.cpp

const char *Section::GetTypeAsCString() const {
   case eSectionTypeAbsoluteAddress:
     return "absolute";
   case eSectionTypeDWARFGNUDebugAltLink:
     return "dwarf-gnu-debugaltlink";
   case eSectionTypeCTF:
     return "ctf";
   case eSectionTypeOther:
     return "regular";
+  case eSectionTypeSwiftModules:
+    return "swift-modules";
   }
   return "unknown";
 }
 
 Section::Section(const ModuleSP &module_sp, ObjectFile *obj_file,
                  user_id_t sect_id, ConstString name,
                  SectionType sect_type, addr_t file_addr, addr_t byte_size,
                  lldb::offset_t file_offset, lldb::offset_t file_size,
bool Section::ContainsOnlyDebugInfo() const {
   case eSectionTypeDWARFDebugTypesDwo:
   case eSectionTypeDWARFDebugNames:
   case eSectionTypeDWARFAppleNames:
   case eSectionTypeDWARFAppleTypes:
   case eSectionTypeDWARFAppleNamespaces:
   case eSectionTypeDWARFAppleObjC:
   case eSectionTypeDWARFGNUDebugAltLink:
   case eSectionTypeCTF:
+  case eSectionTypeSwiftModules:
     return true;
   }
   return false;
 }
 
 
 #pragma mark SectionList
 

lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

return llvm::StringSwitch<SectionType>(Name)
       .Case(".ARM.extab", eSectionTypeARMextab)
       .Cases(".bss", ".tbss", eSectionTypeZeroFill)
       .Case(".ctf", eSectionTypeDebug)
       .Cases(".data", ".tdata", eSectionTypeData)
       .Case(".eh_frame", eSectionTypeEHFrame)
       .Case(".gnu_debugaltlink", eSectionTypeDWARFGNUDebugAltLink)
       .Case(".gosymtab", eSectionTypeGoSymtab)
       .Case(".text", eSectionTypeCode)
+      .Case(".swift_ast", eSectionTypeSwiftModules)
       .Default(eSectionTypeOther);
 }
 
 SectionType ObjectFileELF::GetSectionType(const ELFSectionHeaderInfo &H) const {
   switch (H.sh_type) {
   case SHT_PROGBITS:
     if (H.sh_flags & SHF_EXECINSTR)
       return eSectionTypeCode;

lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp

if (symbol->ValueIsAddress()) {
         case eSectionTypeDWARFDebugTypes:
         case eSectionTypeDWARFDebugTypesDwo:
         case eSectionTypeDWARFAppleNames:
         case eSectionTypeDWARFAppleTypes:
         case eSectionTypeDWARFAppleNamespaces:
         case eSectionTypeDWARFAppleObjC:
         case eSectionTypeDWARFGNUDebugAltLink:
         case eSectionTypeCTF:
+        case eSectionTypeSwiftModules:
           return AddressClass::eDebug;
 
         case eSectionTypeEHFrame:
         case eSectionTypeARMexidx:
         case eSectionTypeARMextab:
         case eSectionTypeCompactUnwind:
           return AddressClass::eRuntime;
 
static lldb::SectionType GetSectionType(uint32_t flags,
   static ConstString g_sect_name_dwarf_apple_namespaces("__apple_namespac");
   static ConstString g_sect_name_dwarf_apple_objc("__apple_objc");
   static ConstString g_sect_name_eh_frame("__eh_frame");
   static ConstString g_sect_name_compact_unwind("__unwind_info");
   static ConstString g_sect_name_text("__text");
   static ConstString g_sect_name_data("__data");
   static ConstString g_sect_name_go_symtab("__gosymtab");
   static ConstString g_sect_name_ctf("__ctf");
+  static ConstString g_sect_name_swift_ast("__swift_ast");
 
   if (section_name == g_sect_name_dwarf_debug_abbrev)
     return eSectionTypeDWARFDebugAbbrev;
   if (section_name == g_sect_name_dwarf_debug_abbrev_dwo)
     return eSectionTypeDWARFDebugAbbrevDwo;
   if (section_name == g_sect_name_dwarf_debug_addr)
     return eSectionTypeDWARFDebugAddr;
   if (section_name == g_sect_name_dwarf_debug_aranges)
static lldb::SectionType GetSectionType(uint32_t flags,
   if (section_name == g_sect_name_compact_unwind)
     return eSectionTypeCompactUnwind;
   if (section_name == g_sect_name_cfstring)
     return eSectionTypeDataObjCCFStrings;
   if (section_name == g_sect_name_go_symtab)
     return eSectionTypeGoSymtab;
   if (section_name == g_sect_name_ctf)
     return eSectionTypeCTF;
+  if (section_name == g_sect_name_swift_ast)
+    return eSectionTypeSwiftModules;
   if (section_name == g_sect_name_objc_data ||
       section_name == g_sect_name_objc_classrefs ||
       section_name == g_sect_name_objc_superrefs ||
       section_name == g_sect_name_objc_const ||
       section_name == g_sect_name_objc_classlist) {
     return eSectionTypeDataPointers;
   }
 

lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp

SectionType section_type =
           .Case(".debug_pubnames", eSectionTypeDWARFDebugPubNames)
           .Case(".debug_pubtypes", eSectionTypeDWARFDebugPubTypes)
           .Case(".debug_ranges", eSectionTypeDWARFDebugRanges)
           .Case(".debug_str", eSectionTypeDWARFDebugStr)
           .Case(".debug_types", eSectionTypeDWARFDebugTypes)
           // .eh_frame can be truncated to 8 chars.
           .Cases(".eh_frame", ".eh_fram", eSectionTypeEHFrame)
           .Case(".gosymtab", eSectionTypeGoSymtab)
+          .Case("swiftast", eSectionTypeSwiftModules)
           .Default(eSectionTypeInvalid);
   if (section_type != eSectionTypeInvalid)
     return section_type;
 
   if (sect.flags & llvm::COFF::IMAGE_SCN_CNT_CODE)
     return eSectionTypeCode;
   if (sect.flags & llvm::COFF::IMAGE_SCN_CNT_INITIALIZED_DATA)
     return eSectionTypeData;

lldb/source/Symbol/ObjectFile.cpp

if (symbol) {
           case eSectionTypeDWARFDebugTypes:
           case eSectionTypeDWARFDebugTypesDwo:
           case eSectionTypeDWARFAppleNames:
           case eSectionTypeDWARFAppleTypes:
           case eSectionTypeDWARFAppleNamespaces:
           case eSectionTypeDWARFAppleObjC:
           case eSectionTypeDWARFGNUDebugAltLink:
           case eSectionTypeCTF:
+          case eSectionTypeSwiftModules:
             return AddressClass::eDebug;
           case eSectionTypeEHFrame:
           case eSectionTypeARMexidx:
           case eSectionTypeARMextab:
           case eSectionTypeCompactUnwind:
             return AddressClass::eRuntime;
           case eSectionTypeELFSymbolTable:
           case eSectionTypeELFDynamicSymbols: