DWARF: Make DIERefs always valid

Summary:
This patch makes the DIERef class always valid by default constructor
and operator bool. This allows one to express the validity of a DIERef
in the type system. Places which are working with potentially-invalid
DIERefs have been updated to use Optional<DIERef> instead.

The constructor taking a DWARFFormValue was not needed, as all places
which were constructing a DIERef this way were immediately converting it
into a DWARFDIE or a user_id. This can be done without constructing an
intermediate DIERef.

Reviewers: JDevlieghere, clayborg, aprantl

Subscribers: arphaman, lldb-commits

Differential Revision: https://reviews.llvm.org/D63399

llvm-svn: 363767

1 files changed, 8 insertions, 12 deletions

diff --git a/lldb/source/Plugins/SymbolFile/DWARF/HashedNameToDIE.cpp b/lldb/source/Plugins/SymbolFile/DWARF/HashedNameToDIE.cpp
index 2cd7c92f1ca..62b0ad37a9f 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/HashedNameToDIE.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/HashedNameToDIE.cpp
@@ -117,13 +117,9 @@ const char *DWARFMappedHash::GetAtomTypeName(uint16_t atom) {
   return "<invalid>";
 }
 
-DWARFMappedHash::DIEInfo::DIEInfo()
-    : tag(0), type_flags(0), qualified_name_hash(0) {}
-
-DWARFMappedHash::DIEInfo::DIEInfo(dw_offset_t c, dw_offset_t o, dw_tag_t t,
-                                  uint32_t f, uint32_t h)
-    : die_ref(DIERef::Section::DebugInfo, c, o), tag(t), type_flags(f),
-      qualified_name_hash(h) {}
+DWARFMappedHash::DIEInfo::DIEInfo(dw_offset_t o, dw_tag_t t, uint32_t f,
+                                  uint32_t h)
+    : die_offset(o), tag(t), type_flags(f), qualified_name_hash(h) {}
 
 DWARFMappedHash::Prologue::Prologue(dw_offset_t _die_base_offset)
     : die_base_offset(_die_base_offset), atoms(), atom_mask(0),
@@ -271,7 +267,7 @@ bool DWARFMappedHash::Header::Read(const lldb_private::DWARFDataExtractor &data,
 
     switch (header_data.atoms[i].type) {
     case eAtomTypeDIEOffset: // DIE offset, check form for encoding
-      hash_data.die_ref.die_offset =
+      hash_data.die_offset =
           DWARFFormValue::IsDataForm(form_value.Form())
               ? form_value.Unsigned()
               : form_value.Reference(header_data.die_base_offset);
@@ -294,7 +290,7 @@ bool DWARFMappedHash::Header::Read(const lldb_private::DWARFDataExtractor &data,
       break;
     }
   }
-  return true;
+  return hash_data.die_offset != DW_INVALID_OFFSET;
 }
 
 DWARFMappedHash::MemoryTable::MemoryTable(
@@ -506,10 +502,10 @@ size_t DWARFMappedHash::MemoryTable::AppendAllDIEsInRange(
       for (uint32_t i = 0; i < count; ++i) {
         DIEInfo die_info;
         if (m_header.Read(m_data, &hash_data_offset, die_info)) {
-          if (die_info.die_ref.die_offset == 0)
+          if (die_info.die_offset == 0)
             done = true;
-          if (die_offset_start <= die_info.die_ref.die_offset &&
-              die_info.die_ref.die_offset < die_offset_end)
+          if (die_offset_start <= die_info.die_offset &&
+              die_info.die_offset < die_offset_end)
             die_info_array.push_back(die_info);
         }
       }