[lldb] Remove DWARFDebugInfo DIERef footguns (#92894)

DWARFDebugInfo doesn't know how to resolve the "file_index" component of
a DIERef. This patch removes GetUnit (in favor of existing
GetUnitContainingDIEOffset) and changes GetDIE to take only the
components it actually uses.

Author: labath

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

@@ -222,10 +222,6 @@ DWARFUnit *DWARFDebugInfo::GetUnitAtOffset(DIERef::Section section,
   return result;
 }
 
-DWARFUnit *DWARFDebugInfo::GetUnit(const DIERef &die_ref) {
-  return GetUnitContainingDIEOffset(die_ref.section(), die_ref.die_offset());
-}
-
 DWARFUnit *
 DWARFDebugInfo::GetUnitContainingDIEOffset(DIERef::Section section,
                                            dw_offset_t die_offset) {
@@ -253,9 +249,8 @@ bool DWARFDebugInfo::ContainsTypeUnits() {
 //
 // Get the DIE (Debug Information Entry) with the specified offset.
 DWARFDIE
-DWARFDebugInfo::GetDIE(const DIERef &die_ref) {
-  DWARFUnit *cu = GetUnit(die_ref);
-  if (cu)
-    return cu->GetNonSkeletonUnit().GetDIE(die_ref.die_offset());
+DWARFDebugInfo::GetDIE(DIERef::Section section, dw_offset_t die_offset) {
+  if (DWARFUnit *cu = GetUnitContainingDIEOffset(section, die_offset))
+    return cu->GetNonSkeletonUnit().GetDIE(die_offset);
   return DWARFDIE(); // Not found
 }

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

@@ -38,11 +38,10 @@ class DWARFDebugInfo {
                              uint32_t *idx_ptr = nullptr);
   DWARFUnit *GetUnitContainingDIEOffset(DIERef::Section section,
                                         dw_offset_t die_offset);
-  DWARFUnit *GetUnit(const DIERef &die_ref);
   DWARFUnit *GetSkeletonUnit(DWARFUnit *dwo_unit);
   DWARFTypeUnit *GetTypeUnitForHash(uint64_t hash);
   bool ContainsTypeUnits();
-  DWARFDIE GetDIE(const DIERef &die_ref);
+  DWARFDIE GetDIE(DIERef::Section section, dw_offset_t die_offset);
 
   enum {
     eDumpFlag_Verbose = (1 << 0),  // Verbose dumping

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

@@ -1761,7 +1761,8 @@ SymbolFileDWARF::GetDIE(const DIERef &die_ref) {
     if (SymbolFileDWARFDebugMap *debug_map = GetDebugMapSymfile()) {
       symbol_file = debug_map->GetSymbolFileByOSOIndex(*file_index); // OSO case
       if (symbol_file)
-        return symbol_file->DebugInfo().GetDIE(die_ref);
+        return symbol_file->DebugInfo().GetDIE(die_ref.section(),
+                                               die_ref.die_offset());
       return DWARFDIE();
     }
 
@@ -1778,7 +1779,7 @@ SymbolFileDWARF::GetDIE(const DIERef &die_ref) {
   if (symbol_file)
     return symbol_file->GetDIE(die_ref);
 
-  return DebugInfo().GetDIE(die_ref);
+  return DebugInfo().GetDIE(die_ref.section(), die_ref.die_offset());
 }
 
 /// Return the DW_AT_(GNU_)dwo_id.
@@ -3786,7 +3787,7 @@ SymbolFileDWARF::FindBlockContainingSpecification(
   // Give the concrete function die specified by "func_die_offset", find the
   // concrete block whose DW_AT_specification or DW_AT_abstract_origin points
   // to "spec_block_die_offset"
-  return FindBlockContainingSpecification(DebugInfo().GetDIE(func_die_ref),
+  return FindBlockContainingSpecification(GetDIE(func_die_ref),
                                           spec_block_die_offset);
 }
 

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

@@ -145,7 +145,7 @@ SymbolFileDWARFDwo::GetTypeSystemForLanguage(LanguageType language) {
 DWARFDIE
 SymbolFileDWARFDwo::GetDIE(const DIERef &die_ref) {
   if (die_ref.file_index() == GetFileIndex())
-    return DebugInfo().GetDIE(die_ref);
+    return DebugInfo().GetDIE(die_ref.section(), die_ref.die_offset());
   return GetBaseSymbolFile().GetDIE(die_ref);
 }