Fix an issue where LLDB was not masking enough bits off of objc classes data() pointers, effectively rendering us unable to generate descriptors for some classes

Fixes rdar://27758358

llvm-svn: 281282

1 files changed, 14 insertions, 1 deletions

diff --git a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.cpp b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.cpp
index 477f4df655e..131f31f69a9 100644
--- a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.cpp
+++ b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.cpp
@@ -28,6 +28,19 @@ bool ClassDescriptorV2::Read_objc_class(
   return ret;
 }
 
+static lldb::addr_t GetClassDataMask(Process *process) {
+  switch (process->GetAddressByteSize()) {
+  case 4:
+    return 0xfffffffcUL;
+  case 8:
+    return 0x00007ffffffffff8UL;
+  default:
+    break;
+  }
+
+  return LLDB_INVALID_ADDRESS;
+}
+
 bool ClassDescriptorV2::objc_class_t::Read(Process *process,
                                            lldb::addr_t addr) {
   size_t ptr_size = process->GetAddressByteSize();
@@ -60,7 +73,7 @@ bool ClassDescriptorV2::objc_class_t::Read(Process *process,
       extractor.GetAddress_unchecked(&cursor); // uintptr_t data_NEVER_USE;
 
   m_flags = (uint8_t)(data_NEVER_USE & (lldb::addr_t)3);
-  m_data_ptr = data_NEVER_USE & ~(lldb::addr_t)3;
+  m_data_ptr = data_NEVER_USE & GetClassDataMask(process);
 
   return true;
 }