[llvm] [DebugInfo] Support to get TU for hash from .debug_types.dwo section in DWARF4. (PR #161067)

[Liu Ke via llvm-commits]

================
@@ -161,17 +161,24 @@ DWARFUnit *DWARFUnitVector::getUnitForOffset(uint64_t Offset) const {
   return nullptr;
 }
 
-DWARFUnit *
-DWARFUnitVector::getUnitForIndexEntry(const DWARFUnitIndex::Entry &E) {
-  const auto *CUOff = E.getContribution(DW_SECT_INFO);
+DWARFUnit *DWARFUnitVector::getUnitForIndexEntry(const DWARFUnitIndex::Entry &E,
+                                                 DWARFSectionKind Sec,
+                                                 const DWARFSection *Section) {
+  const auto *CUOff = E.getContribution(Sec);
   if (!CUOff)
     return nullptr;
 
   uint64_t Offset = CUOff->getOffset();
-  auto end = begin() + getNumInfoUnits();
+  auto begin = this->begin();
+  auto end = begin + getNumInfoUnits();
+
+  if (Sec == DW_SECT_EXT_TYPES) {
+    begin = end;
----------------
Sockke wrote:

For DWARF4 TUs are stored after CUs in DWOUnits vector:
```
  /// Get units from .debug_types.dwo in the DWO context.
  unit_iterator_range dwo_types_section_units() {
    DWARFUnitVector &DWOUnits = State->getDWOUnits();
    return unit_iterator_range(DWOUnits.begin() + DWOUnits.getNumInfoUnits(),
                               DWOUnits.end());
  }
```
`DW_SECT_EXT_TYPES` indicates that DWARF4 .debug_types is being processed.


https://github.com/llvm/llvm-project/pull/161067