Get the bit-field offset & size for ObjC ivars that are bitfields.

<rdar://problem/10535460> lldb expression evaluation doesn't handle bit fields in ObjC classes properly

llvm-svn: 146134

lldb/source/Symbol/ClangASTContext.cpp

@@ -3458,7 +3458,7 @@ ClangASTContext::GetChildClangTypeAtIndex
                             {
                                 if (child_idx == idx)
                                 {
-                                    const ObjCIvarDecl* ivar_decl = *ivar_pos;
+                                    ObjCIvarDecl* ivar_decl = *ivar_pos;
                                     
                                     QualType ivar_qual_type(ivar_decl->getType());
 
@@ -3487,12 +3487,26 @@ ClangASTContext::GetChildClangTypeAtIndex
                                         }
                                     }
                                     
+                                    // Setting this to UINT32_MAX to make sure we don't compute it twice...
+                                    bit_offset = UINT32_MAX;
+                                    
                                     if (child_byte_offset == LLDB_INVALID_IVAR_OFFSET)
                                     {
                                         bit_offset = interface_layout.getFieldOffset (child_idx - superclass_idx);
                                         child_byte_offset = bit_offset / 8;
                                     }
-
+                                    
+                                    // Note, the ObjC Ivar Byte offset is just that, it doesn't account for the bit offset
+                                    // of a bitfield within its containing object.  So regardless of where we get the byte
+                                    // offset from, we still need to get the bit offset for bitfields from the layout.
+                                    
+                                    if (ClangASTContext::FieldIsBitfield (ast, ivar_decl, child_bitfield_bit_size))
+                                    {
+                                        if (bit_offset == UINT32_MAX)
+                                            bit_offset = interface_layout.getFieldOffset (child_idx - superclass_idx);
+                                            
+                                        child_bitfield_bit_offset = bit_offset % 8;
+                                    }
                                     return ivar_qual_type.getAsOpaquePtr();
                                 }
                                 ++child_idx;

lldb/test/lang/objc/objc-ivar-offsets/TestObjCIvarOffsets.py

@@ -56,18 +56,34 @@ class TestObjCIvarOffsets(TestBase):
         
         # Test the value object value for BaseClass->_backed_int
 
+        error = lldb.SBError()
+
         mine_backed_int = mine.GetChildMemberWithName ("_backed_int")
         self.assertTrue(mine_backed_int, "Found mine->backed_int local variable.")
-        backed_value = int (mine_backed_int.GetValue (), 0)
+        backed_value = mine_backed_int.GetValueAsSigned (error)
+        self.assertTrue (error.Success())
         self.assertTrue (backed_value == 1111)
         
         # Test the value object value for DerivedClass->_derived_backed_int
 
         mine_derived_backed_int = mine.GetChildMemberWithName ("_derived_backed_int")
         self.assertTrue(mine_derived_backed_int, "Found mine->derived_backed_int local variable.")
-        derived_backed_value = int (mine_derived_backed_int.GetValue (), 0)
+        derived_backed_value = mine_derived_backed_int.GetValueAsSigned (error)
+        self.assertTrue (error.Success())
         self.assertTrue (derived_backed_value == 3333)
-                                    
+
+        # Make sure we also get bit-field offsets correct:
+
+        mine_flag2 = mine.GetChildMemberWithName ("flag2")
+        self.assertTrue(mine_flag2, "Found mine->flag2 local variable.")
+        flag2_value = int (mine_flag2.GetValue (), 0)
+        self.assertTrue (flag2_value == 7)
+
+        # GetValueAsUnsigned fails for bit-fields:
+#        flag2_value = mine_flag2.GetValueAsUnsigned (error)
+#        self.assertTrue (error.Success())
+#        self.assertTrue (flag2_value == 7)
+        
 if __name__ == '__main__':
     import atexit
     lldb.SBDebugger.Initialize()

lldb/test/lang/objc/objc-ivar-offsets/main.m

@@ -8,6 +8,8 @@ main ()
   mine.unbacked_int = 2222;
   mine.derived_backed_int = 3333;
   mine.derived_unbacked_int = 4444;
+  mine->flag1 = 1;
+  mine->flag2 = 7;
 
   return 0;  // Set breakpoint here.
 }

lldb/test/lang/objc/objc-ivar-offsets/objc-ivar-offsets.h

@@ -17,7 +17,11 @@
 #if !__OBJC2__
   int _derived_unbacked_int;
 #endif
+  @public
+  uint32_t flag1 : 1;
+  uint32_t flag2 : 3;
 }
+
 @property int derived_backed_int;
 @property int derived_unbacked_int;
 @end