split transforms into post-parsing and pre-compilation

Any program rewriting and optimization now happens in compiler-hook.

Author: stylewarning

src/cl-quil.lisp

@@ -5,9 +5,9 @@
 
 (in-package #:cl-quil.frontend)
 
-(defvar *standard-post-process-transforms*
-  '(validate-defgate-loops expand-circuits type-check simplify-individual-instructions)
-  "The standard transforms that are applied by PARSE-QUIL.")
+(defvar *standard-post-parsing-transforms*
+  '(validate-defgate-loops expand-circuits type-check)
+  "The standard transforms that are applied by PARSE-QUIL after parsing. (See also: *STANDARD-PRE-COMPILATION-TRANSFORMS*)")
 
 (define-condition ambiguous-definition-condition ()
   ((instruction :initarg :instruction
@@ -118,8 +118,9 @@ This also signals ambiguous definitions, which may be handled as needed."
 2. PARSER-EXTENSIONS is a list of parser functions which PARSE-PROGRAM-LINES may dispatch to.
 3. LEXER-EXTENSIONS is a list of lexer functions which LINE-LEXER may dispatch to."
   (handler-bind
-      ;; We disallow multiple declarations of the same memory region (even if equivalent).
-      ;; Otherwise, for gate or circuit definitions, the default choice is to "accept the mystery."
+      ;; We disallow multiple declarations of the same memory region
+      ;; (even if equivalent). Otherwise, for gate or circuit
+      ;; definitions, the default choice is to "accept the mystery."
       ((ambiguous-definition-condition (a:disjoin
                                         #'error-on-ambiguous-memory-declaration
                                         ambiguous-definition-handler)))
@@ -163,7 +164,7 @@ This also signals ambiguous definitions, which may be handled as needed."
                (return nil)))))))
 
 (defun parse (string &key originating-file
-                       (transforms *standard-post-process-transforms*)
+                       (transforms *standard-post-parsing-transforms*)
                        (ambiguous-definition-handler #'continue))
   "Parse the input STRING which can be either Quil or OpenQASM code."
   (if (%check-for-qasm-header string)
@@ -174,7 +175,7 @@ This also signals ambiguous definitions, which may be handled as needed."
                   :ambiguous-definition-handler ambiguous-definition-handler)))
 
 (defun parse-quil (string &key originating-file
-                            (transforms *standard-post-process-transforms*)
+                            (transforms *standard-post-parsing-transforms*)
                             (ambiguous-definition-handler #'continue))
   "Parse and process the Quil string STRING, which originated from the file ORIGINATING-FILE. Transforms in TRANSFORMS are applied in-order to the processed Quil string.
 
@@ -263,7 +264,7 @@ In the presence of multiple definitions with a common signature, a signal is rai
           (read-it filename)))))
 
 (defun safely-parse-quil (string &key originating-file
-                                   (transforms *standard-post-process-transforms*)
+                                   (transforms *standard-post-parsing-transforms*)
                                    (ambiguous-definition-handler #'continue))
   "Safely parse a Quil string STRING."
   (flet ((parse-it (string)

src/compiler-hook.lisp

@@ -11,6 +11,11 @@
 ;;;; For historical reasons, this entry point has been called
 ;;;; "COMPILER-HOOK".
 
+
+(defvar *standard-pre-compilation-transforms*
+  '(simplify-individual-instructions)
+  "The standard transforms that are applied by COMPILER-HOOK before compilation. (See also: *STANDARD-POST-PARSING-TRANSFORMS*)")
+
 ;; Forward declaration from compressor.lisp
 (declaim (special *compressor-passes*))
 
@@ -22,6 +27,7 @@
                       &key
                         (protoquil nil)
                         (rewiring-type (prog-initial-rewiring-heuristic parsed-program chip-specification))
+                        (transforms *standard-pre-compilation-transforms*)
                         (destructive nil))
   "Runs a full compiler pass on a parsed-program object.
 
@@ -55,8 +61,15 @@ Returns a value list: (processed-program, of type parsed-program
              (> (qubits-needed parsed-program)
                 (length (chip-spec-live-qubits chip-specification)))
              (not (parsed-program-has-preserve-blocks-p parsed-program)))
+    (format-noise "COMPILER-HOOK: Compressing qubits.")
     (setf parsed-program (compress-qubits parsed-program)))
 
+  ;; Apply transforms
+  (dolist (xform transforms)
+    (format-noise "COMPILER-HOOK: Applying transform ~A." xform)
+    (setf parsed-program (transform xform parsed-program)))
+  
+  ;; Warm the lookup cache
   (warm-chip-spec-lookup-cache chip-specification)
 
   ;; we disallow compilation of programs that use memory aliasing