Added NON_VOLATILE pragma

src/pragmas.lisp

@@ -138,6 +138,19 @@ Expected syntax: PRAGMA REWIRING_SEARCH [\"A*\"|\"GREEDY-QUBIT\"|\"GREEDY-PATH\"
   (:display-string
    (prin1-to-string (symbol-name swap-search-type))))
 
+
+(define-pragma "NON_VOLATILE" pragma-non-volatile
+  (:documentation "PRAGMA indicating that declared memory can be assumed to be non-volatile - it will not be modified outside of the Quil program in which it is declared.
+
+Expected syntax: PRAGMA NON_VOLATILE identifier")
+  (:global t)
+  (:slots (memory-name cl-quil::memory-name))
+  (:words (name string))
+  (:initialization
+   (setf memory-name (cl-quil::memory-name name)))
+  (:display-string
+   (princ-to-string (cl-quil::memory-name-region-name memory-name))))
+
 (defun parsed-program-has-pragma-p (parsed-program &optional (pragma-type 'pragma))
   "Return T if PARSED-PROGRAM's executable code contains any pragma. Optionally use PRAGMA-TYPE to restrict to a particular pragma type."
   (some (a:rcurry #'typep pragma-type)