Add a distinction in an apple accelerator table between IsValid and
HasContent.  If we have a valid accelerator table which has no
content, we want to depend on that (empty) table as the authoritative
source instead of reading through all the debug info for lookups.
<rdar://problem/30867462> 

llvm-svn: 297441
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index 856c371..40064de 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -448,19 +448,19 @@
   if (m_data_apple_names.m_data.GetByteSize() > 0) {
     m_apple_names_ap.reset(new DWARFMappedHash::MemoryTable(
         m_data_apple_names.m_data, get_debug_str_data(), ".apple_names"));
-    if (m_apple_names_ap->IsValid())
-      m_using_apple_tables = true;
-    else
+    if (!m_apple_names_ap->IsValid())
       m_apple_names_ap.reset();
+    if (m_apple_names_ap->HasContent())
+      m_using_apple_tables = true;
   }
   get_apple_types_data();
   if (m_data_apple_types.m_data.GetByteSize() > 0) {
     m_apple_types_ap.reset(new DWARFMappedHash::MemoryTable(
         m_data_apple_types.m_data, get_debug_str_data(), ".apple_types"));
-    if (m_apple_types_ap->IsValid())
-      m_using_apple_tables = true;
-    else
+    if (!m_apple_types_ap->IsValid())
       m_apple_types_ap.reset();
+    if (m_apple_types_ap->HasContent())
+      m_using_apple_tables = true;
   }
 
   get_apple_namespaces_data();
@@ -468,20 +468,20 @@
     m_apple_namespaces_ap.reset(new DWARFMappedHash::MemoryTable(
         m_data_apple_namespaces.m_data, get_debug_str_data(),
         ".apple_namespaces"));
-    if (m_apple_namespaces_ap->IsValid())
-      m_using_apple_tables = true;
-    else
+    if (!m_apple_namespaces_ap->IsValid())
       m_apple_namespaces_ap.reset();
+    if (m_apple_namespaces_ap->HasContent())
+      m_using_apple_tables = true;
   }
 
   get_apple_objc_data();
   if (m_data_apple_objc.m_data.GetByteSize() > 0) {
     m_apple_objc_ap.reset(new DWARFMappedHash::MemoryTable(
         m_data_apple_objc.m_data, get_debug_str_data(), ".apple_objc"));
-    if (m_apple_objc_ap->IsValid())
-      m_using_apple_tables = true;
-    else
+    if (!m_apple_objc_ap->IsValid())
       m_apple_objc_ap.reset();
+    if (m_apple_objc_ap->HasContent())
+      m_using_apple_tables = true;
   }
 }