Update debug printers for Arc.

src/etc/gdb_providers.py

@@ -168,7 +168,16 @@ def __init__(self, valobj, is_atomic=False):
         self.ptr = unwrap_unique_or_non_null(valobj["ptr"])
         self.value = self.ptr["data" if is_atomic else "value"]
         self.strong = self.ptr["strong"]["v" if is_atomic else "value"]["value"]
-        self.weak = self.ptr["weak"]["v" if is_atomic else "value"]["value"] - 1
+        self.weak = self.ptr["weak"]["v" if is_atomic else "value"]["value"]
+        if is_atomic:
+            if self.weak % 2 == 1:
+                self.weak = 0
+            elif self.weak > 0:
+                self.weak >>= 1
+                self.weak -= 1
+            self.strong >>= 2
+        else:
+            self.weak -= 1
 
     def to_string(self):
         if self.is_atomic:

src/etc/lldb_providers.py

@@ -610,6 +610,8 @@ def __init__(self, valobj, dict, is_atomic=False):
 
         self.value_builder = ValueBuilder(valobj)
 
+        self.is_atomic = is_atomic
+
         self.update()
 
     def num_children(self):
@@ -641,7 +643,16 @@ def get_child_at_index(self, index):
     def update(self):
         # type: () -> None
         self.strong_count = self.strong.GetValueAsUnsigned()
-        self.weak_count = self.weak.GetValueAsUnsigned() - 1
+        self.weak_count = self.weak.GetValueAsUnsigned()
+        if self.is_atomic:
+            if self.weak_count % 2 == 1:
+                self.weak_count = 0
+            elif self.weak_count > 0:
+                self.weak_count >>= 1
+                self.weak_count -= 1
+            self.strong_count >>= 2
+        else:
+            self.weak_count -= 1
 
     def has_children(self):
         # type: () -> bool