ir: IRAssignable add helper property to give a sorted list of all uses (read or write) of the value

compiler/ir.py

@@ -128,6 +128,15 @@ class IRAssignable(IRValue, metaclass=abc.ABCMeta):
         super().__init__(location)
         self.writers: list[IRAction] = []
 
+    @property
+    def sorted_users(self) -> list[IRAction]:
+        assert all((x.ir_location.line != -1 for x in self.readers))
+        assert all((x.ir_location.line != -1 for x in self.writers))
+
+        users = self.readers + self.writers
+        users.sort(key=lambda user: user.ir_location)
+        return users
+
     def __str__(self):
         return self.codegen()