Fixes to the Objective-C V2 runtime:

- Only read the statically-defined isa table in the
  shared cache once.  Only the dynamically-constructed
  isa table can change.

- Ignore the statically-defined isa table if its
  version isn't what we expect.

llvm-svn: 166856

lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp

@@ -113,7 +113,8 @@ AppleObjCRuntimeV2::AppleObjCRuntimeV2 (Process *process,
     m_type_vendor_ap (),
     m_isa_hash_table_ptr (LLDB_INVALID_ADDRESS),
     m_hash_signature (),
-    m_has_object_getClass (false)
+    m_has_object_getClass (false),
+    m_loaded_objc_opt (false)
 {
     static const ConstString g_gdb_object_getClass("gdb_object_getClass");
     m_has_object_getClass = (objc_module_sp->FindFirstSymbolWithNameAndType(g_gdb_object_getClass, eSymbolTypeCode) != NULL);
@@ -736,6 +737,9 @@ public:
         m_version = m_process->ReadUnsignedIntegerFromMemory(cursor, sizeof(uint32_t), 0, err);
         cursor += sizeof(uint32_t);
         
+        if (!IsValid())
+            return;
+        
         // int32_t selopt_offset;
         cursor += sizeof(int32_t);
         
@@ -750,9 +754,6 @@ public:
             cursor += sizeof(int32_t);
         }
         
-        if (m_version != 12)
-            return;
-        
         m_clsopt_ptr = load_addr + m_clsopt_offset;
         
         cursor = m_clsopt_ptr;
@@ -913,6 +914,9 @@ public:
     
     const_iterator begin ()
     {
+        if (!IsValid())
+            return m_end_iterator;
+        else
             return const_iterator(*this, (int64_t)m_capacity + (int64_t)m_duplicateCount);
     }
     
@@ -922,6 +926,11 @@ public:
     }
     
 private:
+    bool IsValid()
+    {
+        return (m_version == 12);
+    }
+    
     // contents of objc_opt struct
     uint32_t m_version;
     int32_t m_clsopt_offset;
@@ -1756,6 +1765,10 @@ AppleObjCRuntimeV2::UpdateISAToDescriptorMapIfNeeded()
                     m_isa_to_descriptor_cache[elt.second] = descriptor_sp;
                 }
                 
+                if (!m_loaded_objc_opt)
+                {
+                    m_loaded_objc_opt = true;
+                    
                     ObjectFile *objc_object = objc_module_sp->GetObjectFile();
                     
                     if (objc_object)
@@ -1799,6 +1812,7 @@ AppleObjCRuntimeV2::UpdateISAToDescriptorMapIfNeeded()
                 }
             }
         }
+    }
     else
     {
         m_isa_to_descriptor_cache_stop_id = UINT32_MAX;

lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.h

@@ -142,6 +142,7 @@ private:
     lldb::addr_t                        m_isa_hash_table_ptr;
     HashTableSignature                  m_hash_signature;
     bool                                m_has_object_getClass;
+    bool                                m_loaded_objc_opt;
     
     static const char *g_find_class_name_function_name;
     static const char *g_find_class_name_function_body;