[nfc] [lldb] 1/2: Fix DW_AT_ranges DW_FORM_sec_offset not using DW_AT_rnglists_base (used by GCC)

[jankratochvil]

Summary

Refactor code only for D98289.

[clayborg]

Looks good as long as we fix to DWARFUnit::GetRnglist() to not return a full copy of the "llvm::Optional<llvm::DWARFDebugRnglistTable>" each time it is called.

lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp

503–505

Return "const llvm::Optional<llvm::DWARFDebugRnglistTable> &" to avoid making a copy.

[jankratochvil]

The patch now requires D99731.

[jankratochvil]

lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp

503–505

That was horrible, thanks for catching it.

lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h

public:
   /// Return a list of address ranges retrieved from an encoded range
   /// list whose offset is found via a table lookup given an index (DWARF v5
   /// and later).
   llvm::Expected<DWARFRangeList> FindRnglistFromIndex(uint32_t index);
 
   /// Return a rangelist's offset based on an index. The index designates
   /// an entry in the rangelist table's offset array and is supplied by
   /// DW_FORM_rnglistx.
-  llvm::Optional<uint64_t> GetRnglistOffset(uint32_t Index) const {
-    if (!m_rnglist_table)
-      return llvm::None;
-    if (llvm::Optional<uint64_t> off = m_rnglist_table->getOffsetEntry(
-            m_dwarf.GetDWARFContext().getOrLoadRngListsData().GetAsLLVM(),
-            Index))
-      return *off + m_ranges_base;
-    return llvm::None;
-  }
+  llvm::Optional<uint64_t> GetRnglistOffset(uint32_t Index);
 
   llvm::Optional<uint64_t> GetLoclistOffset(uint32_t Index) {
     if (!m_loclist_table_header)
       return llvm::None;
 
     llvm::Optional<uint64_t> Offset = m_loclist_table_header->getOffsetEntry(
         m_dwarf.GetDWARFContext().getOrLoadLocListsData().GetAsLLVM(), Index);
     if (!Offset)
protected:
   // Get all DWARF debug informration entries. Parse all DIEs if needed.
   const DWARFDebugInfoEntry *DIEPtr() {
     ExtractDIEsIfNeeded();
     if (m_die_array.empty())
       return NULL;
     return &m_die_array[0];
   }
 
+  const llvm::Optional<llvm::DWARFDebugRnglistTable> &GetRnglist();
+
   SymbolFileDWARF &m_dwarf;
   std::shared_ptr<DWARFUnit> m_dwo;
   DWARFUnitHeader m_header;
   const DWARFAbbreviationDeclarationSet *m_abbrevs = nullptr;
   void *m_user_data = nullptr;
   // The compile unit debug information entry item
   DWARFDebugInfoEntry::collection m_die_array;
   mutable llvm::sys::RWMutex m_die_array_mutex;

lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp

if (auto table_or_error = ParseListTableHeader<llvm::DWARFDebugRnglistTable>(
           ranges_base, DWARF32))
     m_rnglist_table = std::move(table_or_error.get());
   else
     GetSymbolFileDWARF().GetObjectFile()->GetModule()->ReportError(
         "Failed to extract range list table at offset 0x%" PRIx64 ": %s",
         ranges_base, toString(table_or_error.takeError()).c_str());
 }
 
+const llvm::Optional<llvm::DWARFDebugRnglistTable> &DWARFUnit::GetRnglist() {
+  return m_rnglist_table;
+}
+
+llvm::Optional<uint64_t> DWARFUnit::GetRnglistOffset(uint32_t Index) {
+  if (!GetRnglist())
+    return llvm::None;
+  if (llvm::Optional<uint64_t> off = GetRnglist()->getOffsetEntry(
+          m_dwarf.GetDWARFContext().getOrLoadRngListsData().GetAsLLVM(), Index))
+    return *off + m_ranges_base;
+  return llvm::None;
+}
+
 void DWARFUnit::SetStrOffsetsBase(dw_offset_t str_offsets_base) {
   m_str_offsets_base = str_offsets_base;
 }
 
 // It may be called only with m_die_array_mutex held R/W.
 void DWARFUnit::ClearDIEsRWLocked() {
   m_die_array.clear();
   m_die_array.shrink_to_fit();
if (GetVersion() <= 4) {
     if (!debug_ranges)
       return llvm::make_error<llvm::object::GenericBinaryError>(
           "No debug_ranges section");
     DWARFRangeList ranges;
     debug_ranges->FindRanges(this, offset, ranges);
     return ranges;
   }
 
-  if (!m_rnglist_table)
+  if (!GetRnglist())
     return llvm::createStringError(errc::invalid_argument,
                                    "missing or invalid range list table");
 
-  auto range_list_or_error = m_rnglist_table->findList(
+  auto range_list_or_error = GetRnglist()->findList(
       m_dwarf.GetDWARFContext().getOrLoadRngListsData().GetAsLLVM(), offset);
   if (!range_list_or_error)
     return range_list_or_error.takeError();
 
   llvm::Expected<llvm::DWARFAddressRangesVector> llvm_ranges =
       range_list_or_error->getAbsoluteRanges(
           llvm::object::SectionedAddress{GetBaseAddress()},
           GetAddressByteSize(), [&](uint32_t index) {
DWARFUnit::FindRnglistFromOffset(dw_offset_t offset) {
   }
   return ranges;
 }
 
 llvm::Expected<DWARFRangeList>
 DWARFUnit::FindRnglistFromIndex(uint32_t index) {
   if (llvm::Optional<uint64_t> offset = GetRnglistOffset(index))
     return FindRnglistFromOffset(*offset);
-  if (m_rnglist_table)
+  if (GetRnglist())
     return llvm::createStringError(errc::invalid_argument,
                                    "invalid range list table index %d", index);
 
   return llvm::createStringError(errc::invalid_argument,
                                  "missing or invalid range list table");
 }