DWARFContext: Return empty data extractors instead of null pointers

Summary:
There are several reasons for doing this:
- generally, there's no reason to differentiate between a section being
  absent and it being present, but empty
- it matches more closely what llvm DWARF parser is doing (which also
  doesn't differentiate the two cases)
- SymbolFileDWARF also doesn't differentiate the two cases, which makes
  porting the rest of sections easier
- it fixes a bug in how the return-null-if-empty logic was implemented
  (it returned nullptr only the second time we tried to get the
  debug_aranges section), which meant that we hit an assert when trying
  to parse an empty-but-present section

Reviewers: JDevlieghere, clayborg, aprantl

Subscribers: zturner, lldb-commits

Differential Revision: https://reviews.llvm.org/D61942

llvm-svn: 360874

1 files changed, 3 insertions, 6 deletions

diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp
index de4a48a2c06..0daf489f4d5 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp
@@ -44,13 +44,10 @@ llvm::Expected<DWARFDebugAranges &> DWARFDebugInfo::GetCompileUnitAranges() {
   assert(m_dwarf2Data);
 
   m_cu_aranges_up = llvm::make_unique<DWARFDebugAranges>();
-  const DWARFDataExtractor *debug_aranges_data =
+  const DWARFDataExtractor &debug_aranges_data =
       m_context.getOrLoadArangesData();
-  if (debug_aranges_data) {
-    llvm::Error error = m_cu_aranges_up->extract(*debug_aranges_data);
-    if (error)
-      return std::move(error);
-  }
+  if (llvm::Error error = m_cu_aranges_up->extract(debug_aranges_data))
+    return std::move(error);
 
   // Make a list of all CUs represented by the arange data in the file.
   std::set<dw_offset_t> cus_with_data;