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

2 files changed, 17 insertions, 13 deletions

diff --git a/lldb/include/lldb/Core/MappedHash.h b/lldb/include/lldb/Core/MappedHash.h
index 76070761efb..32d8d7ba8e3 100644
--- a/lldb/include/lldb/Core/MappedHash.h
+++ b/lldb/include/lldb/Core/MappedHash.h
@@ -353,7 +353,11 @@ public:
     bool IsValid() const {
       return m_header.version == 1 &&
              m_header.hash_function == eHashFunctionDJB &&
-             m_header.bucket_count > 0 && m_header.hashes_count > 0;
+             m_header.bucket_count > 0;
+    }
+
+    bool HasContent() const {
+        return IsValid() && m_header.hashes_count > 0;
     }
 
     uint32_t GetHashIndex(uint32_t bucket_idx) const {
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index 856c371636d..40064de100b 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -448,19 +448,19 @@ void SymbolFileDWARF::InitializeObject() {
   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 @@ void SymbolFileDWARF::InitializeObject() {
     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;
   }
 }