[Lldb-commits] [lldb] [lldb] Fix a crash when using .dwp files and make type lookup reliable with the index cache (PR #79544)

[via lldb-commits]

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@@ -81,27 +81,88 @@ void DWARFDebugInfo::ParseUnitsFor(DIERef::Section section) {
                                 : m_context.getOrLoadDebugInfoData();
   lldb::offset_t offset = 0;
   while (data.ValidOffset(offset)) {
-    llvm::Expected<DWARFUnitSP> unit_sp = DWARFUnit::extract(
+    llvm::Expected<DWARFUnitSP> expected_unit_sp = DWARFUnit::extract(
         m_dwarf, m_units.size(), data, section, &offset);
 
-    if (!unit_sp) {
+    if (!expected_unit_sp) {
       // FIXME: Propagate this error up.
-      llvm::consumeError(unit_sp.takeError());
+      llvm::consumeError(expected_unit_sp.takeError());
       return;
     }
 
+    DWARFUnitSP unit_sp = *expected_unit_sp;
+
     // If it didn't return an error, then it should be returning a valid Unit.
-    assert(*unit_sp);
-    m_units.push_back(*unit_sp);
-    offset = (*unit_sp)->GetNextUnitOffset();
+    assert((bool)unit_sp);
+
+    // Keep a map of DWO ID back to the skeleton units. Sometimes accelerator
+    // table lookups can cause the DWO files to be accessed before the skeleton
+    // compile unit is parsed, so we keep a map to allow us to match up the DWO
+    // file to the back to the skeleton compile units.
+    if (unit_sp->GetUnitType() == lldb_private::dwarf::DW_UT_skeleton) {
+      if (std::optional<uint64_t> unit_dwo_id = unit_sp->GetHeaderDWOId())
+        m_dwarf5_dwo_id_to_skeleton_unit[*unit_dwo_id] = unit_sp.get();
+    }
 
-    if (auto *type_unit = llvm::dyn_cast<DWARFTypeUnit>(unit_sp->get())) {
+    m_units.push_back(unit_sp);
+    offset = unit_sp->GetNextUnitOffset();
+
+    if (auto *type_unit = llvm::dyn_cast<DWARFTypeUnit>(unit_sp.get())) {
       m_type_hash_to_unit_index.emplace_back(type_unit->GetTypeHash(),
-                                             unit_sp.get()->GetID());
+                                             unit_sp->GetID());
     }
   }
 }
 
+DWARFUnit *DWARFDebugInfo::GetSkeletonUnit(DWARFUnit *dwo_unit) {
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jeffreytan81 wrote:

Maybe return a `llvm::optional<DWARFUnit>` instead of raw pointer to force caller to handle null case explicitly.

https://github.com/llvm/llvm-project/pull/79544