3 ;;; Code generation protocol
5 ;;; (c) 2009 Straylight/Edgeware
8 ;;;----- Licensing notice ---------------------------------------------------
10 ;;; This file is part of the Sensible Object Design, an object system for C.
12 ;;; SOD is free software; you can redistribute it and/or modify
13 ;;; it under the terms of the GNU General Public License as published by
14 ;;; the Free Software Foundation; either version 2 of the License, or
15 ;;; (at your option) any later version.
17 ;;; SOD is distributed in the hope that it will be useful,
18 ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ;;; GNU General Public License for more details.
22 ;;; You should have received a copy of the GNU General Public License
23 ;;; along with SOD; if not, write to the Free Software Foundation,
24 ;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
28 ;;;--------------------------------------------------------------------------
33 (export 'format-temporary-name)
34 (defgeneric format-temporary-name (var stream)
36 "Write the name of a temporary variable VAR to STREAM."))
38 (export 'var-in-use-p)
39 (defgeneric var-in-use-p (var)
41 "Answer whether VAR is currently being used. See `with-temporary-var'.")
43 "Non-temporary variables are always in use."
44 (declare (ignore var))
46 (defgeneric (setf var-in-use-p) (value var)
48 "Record whether VAR is currently being used. See `with-temporary-var'."))
52 (export '(temporary-name temp-tag))
53 (defclass temporary-name ()
54 ((tag :initarg :tag :reader temp-tag))
56 "Base class for temporary variable and argument names."))
58 ;; Important temporary names.
60 (export '(*sod-ap* *sod-master-ap*))
61 (defparameter *sod-ap*
62 (make-instance 'temporary-name :tag "sod__ap"))
63 (defparameter *sod-master-ap*
64 (make-instance 'temporary-name :tag "sod__master_ap"))
65 (defparameter *sod-tmp-ap*
66 (make-instance 'temporary-name :tag "sod__tmp_ap"))
67 (defparameter *sod-tmp-val*
68 (make-instance 'temporary-name :tag "sod__t"))
70 (export '*null-pointer*)
71 (defparameter *null-pointer* "NULL")
73 ;;;--------------------------------------------------------------------------
81 "A base class for instructions.
83 An `instruction' is anything which might be useful to string into a code
84 generator. Both statements and expressions can be represented by trees of
85 instructions. The `definst' macro is a convenient way of defining new
88 The only important protocol for instructions is output, which is achieved
89 by calling `print-object' with `*print-escape*' nil.
91 This doesn't really do very much, but it acts as a handy marker for
92 instruction subclasses."))
95 (defgeneric inst-metric (inst)
97 "Returns a `metric' describing how complicated INST is.
99 The default metric of an inst node is simply 1; `inst' subclasses
100 generated by `definst' (q.v.) have an automatically generated method which
101 returns one plus the sum of the metrics of the node's children.
103 This isn't intended to be a particularly rigorous definition. Its purpose
104 is to allow code generators to make decisions about inlining or calling
105 code fairly simply.")
107 (declare (ignore inst))
109 (:method ((inst null))
110 (declare (ignore inst))
112 (:method ((inst list))
113 (reduce #'+ inst :key #'inst-metric)))
115 ;; Instruction definition.
118 (defmacro definst (code (streamvar &key export) args &body body)
119 "Define an instruction type and describe how to output it.
121 An `inst' can represent any structured piece of output syntax: a
122 statement, expression or declaration, for example. This macro defines the
125 * A class `CODE-inst' to represent the instruction.
127 * Instance slots named after the ARGS, with matching keyword initargs,
128 and `inst-ARG' readers.
130 * A constructor `make-CODE-inst' which accepts the ARGS (as an ordinary
131 BVL) as arguments and returns a fresh instance.
133 * A print method, which prints a diagnostic dump if `*print-escape*' is
134 set, or invokes the BODY (with STREAMVAR bound to the output stream)
135 otherwise. The BODY is expected to produce target code at this
138 If EXPORT is non-nil, then export the `CODE-inst' and `make-CODE-inst'
141 (let* ((inst-var (gensym "INST"))
142 (class-name (symbolicate code '-inst))
143 (constructor-name (symbolicate 'make- code '-inst))
144 (slots (mapcan (lambda (arg)
145 (if (listp arg) (list (car arg))
146 (let ((name (symbol-name arg)))
147 (if (and (plusp (length name))
148 (char/= (char name 0) #\&))
152 (keys (mapcar (lambda (arg) (intern (symbol-name arg) :keyword))
155 (defclass ,class-name (inst)
156 ,(mapcar (lambda (slot key)
157 `(,slot :initarg ,key
158 :reader ,(symbolicate 'inst- slot)))
160 (defun ,constructor-name (,@args)
161 (make-instance ',class-name ,@(mappend #'list keys slots)))
162 (defmethod inst-metric ((,inst-var ,class-name))
163 (with-slots (,@slots) ,inst-var
164 (+ 1 ,@(mapcar (lambda (slot) `(inst-metric ,slot)) slots))))
165 (defmethod print-object ((,inst-var ,class-name) ,streamvar)
166 (with-slots (,@slots) ,inst-var
168 (print-unreadable-object (,inst-var ,streamvar :type t)
169 (format stream "~@<~@{~S ~@_~S~^ ~_~}~:>"
170 ,@(mappend #'list keys slots)))
171 (block ,code ,@body))))
172 ,@(and export `((export '(,class-name ,constructor-name
173 ,@(mapcar (lambda (slot)
174 (symbolicate 'inst- slot))
178 ;; Formatting utilities.
180 (defun format-compound-statement* (stream child morep thunk)
181 "Underlying function for `format-compound-statement'."
182 (cond ((typep child 'block-inst)
183 (funcall thunk stream)
184 (write-char #\space stream)
186 (when morep (write-char #\space stream)))
188 (pprint-logical-block (stream nil)
189 (funcall thunk stream)
190 (write-char #\space stream)
191 (pprint-indent :block 2 stream)
192 (pprint-newline :linear stream)
194 (pprint-indent :block 0 stream)
197 (write-char #\space stream)
198 (pprint-newline :linear stream))
200 (pprint-newline :mandatory stream)))))))
202 (export 'format-compound-statement)
203 (defmacro format-compound-statement
204 ((stream child &optional morep) &body body)
205 "Format a compound statement to STREAM.
207 The introductory material is printed by BODY. The CHILD is formatted
208 properly according to whether it's a `block-inst'. If MOREP is true, then
209 allow for more stuff following the child."
210 `(format-compound-statement* ,stream ,child ,morep
211 (lambda (,stream) ,@body)))
213 ;; Important instruction classes.
215 ;; HACK: Some of the slot names we'd like to use are external symbols in our
216 ;; package or the `common-lisp' package. Use gensyms for these slot names to
217 ;; prevent them from leaking.
219 (definst var (stream :export t) (name #1=#:type &optional init)
220 (pprint-c-type #1# stream name)
222 (format stream " = ~A" init))
223 (write-char #\; stream))
225 (definst function (stream :export t) (name #1=#:type body)
226 (pprint-logical-block (stream nil)
227 (princ "static " stream)
228 (pprint-c-type #1# stream name)
229 (format stream "~:@_~A~:@_~:@_" body)))
231 ;; Expression statements.
232 (definst expr (stream :export t) (#1=#:expr)
233 (format stream "~A;" #1#))
234 (definst set (stream :export t) (var #1=#:expr)
235 (format stream "~@<~A = ~@_~2I~A;~:>" var #1#))
236 (definst update (stream :export t) (var op #1=#:expr)
237 (format stream "~@<~A ~A= ~@_~2I~A;~:>" var op #1#))
239 ;; Special kinds of expressions.
240 (definst call (stream :export t) (#1=#:func &rest args)
241 (format stream "~A(~@<~{~A~^, ~_~}~:>)" #1# args))
243 ;; Simple statements.
244 (definst return (stream :export t) (#1=#:expr)
245 (format stream "return~@[ (~A)~];" #1#))
246 (definst break (stream :export t) ()
247 (format stream "break;"))
248 (definst continue (stream :export t) ()
249 (format stream "continue;"))
251 ;; Compound statements.
253 (definst block (stream :export t) (decls body)
254 (format stream "{~:@_~@< ~2I~@[~{~A~:@_~}~:@_~]~{~A~^~:@_~}~:>~:@_}"
257 (definst if (stream :export t) (#1=#:cond conseq &optional alt)
259 (loop (format-compound-statement (stream conseq (if alt t nil))
260 (format stream "~A (~A)" stmt #1#))
263 (if-inst (setf stmt "else if"
265 conseq (inst-conseq alt)
267 (t (format-compound-statement (stream alt)
268 (format stream "else"))
271 (definst while (stream :export t) (#1=#:cond body)
272 (format-compound-statement (stream body)
273 (format stream "while (~A)" #1#)))
275 (definst do-while (stream :export t) (body #1=#:cond)
276 (format-compound-statement (stream body :space)
277 (write-string "do" stream))
278 (format stream "while (~A);" #1#))
280 ;;;--------------------------------------------------------------------------
285 (export 'codegen-functions)
286 (defgeneric codegen-functions (codegen)
288 "Return the list of `function-inst's of completed functions."))
291 (defgeneric ensure-var (codegen name type &optional init)
293 "Add a variable to CODEGEN's list.
295 The variable is called NAME (which should be comparable using `equal' and
296 print to an identifier) and has the given TYPE. If INIT is present and
297 non-nil it is an expression `inst' used to provide the variable with an
300 (export '(emit-inst emit-insts))
301 (defgeneric emit-inst (codegen inst)
303 "Add INST to the end of CODEGEN's list of instructions."))
304 (defgeneric emit-insts (codegen insts)
306 "Add a list of INSTS to the end of CODEGEN's list of instructions.")
307 (:method (codegen insts)
308 (dolist (inst insts) (emit-inst codegen inst))))
310 (export '(emit-decl emit-decls))
311 (defgeneric emit-decl (codegen inst)
313 "Add INST to the end of CODEGEN's list of declarations."))
314 (defgeneric emit-decls (codegen insts)
316 "Add a list of INSTS to the end of CODEGEN's list of declarations."))
318 (export 'codegen-push)
319 (defgeneric codegen-push (codegen)
321 "Pushes the current code generation state onto a stack.
323 The state consists of the accumulated variables and instructions."))
325 (export 'codegen-pop)
326 (defgeneric codegen-pop (codegen)
328 "Pops a saved state off of the CODEGEN's stack.
330 Returns the newly accumulated variables and instructions as lists, as
333 (export 'codegen-add-function)
334 (defgeneric codegen-add-function (codegen function)
336 "Adds a function to CODEGEN's list.
338 Actually, we're not picky: FUNCTION can be any kind of object that you're
339 willing to find in the list returned by `codegen-functions'."))
341 (export 'temporary-var)
342 (defgeneric temporary-var (codegen type)
344 "Return the name of a temporary variable.
346 The temporary variable will have the given TYPE, and will be marked
347 in-use. You should clear the in-use flag explicitly when you've finished
348 with the variable -- or, better, use `with-temporary-var' to do the
349 cleanup automatically."))
351 (export 'codegen-build-function)
352 (defun codegen-build-function (codegen name type vars insts)
353 "Build a function and add it to CODEGEN's list.
355 Returns the function's name."
356 (codegen-add-function codegen
357 (make-function-inst name type
358 (make-block-inst vars insts)))
361 (export 'codegen-pop-block)
362 (defgeneric codegen-pop-block (codegen)
364 "Makes a block (`block-inst') out of the completed code in CODEGEN.")
366 (multiple-value-bind (vars insts) (codegen-pop codegen)
367 (make-block-inst vars insts))))
369 (export 'codegen-pop-function)
370 (defgeneric codegen-pop-function (codegen name type)
372 "Makes a function out of the completed code in CODEGEN.
374 The NAME can be any object you like. The TYPE should be a function type
375 object which includes argument names. The return value is the NAME.")
376 (:method (codegen name type)
377 (multiple-value-bind (vars insts) (codegen-pop codegen)
378 (codegen-build-function codegen name type vars insts))))
380 (export 'with-temporary-var)
381 (defmacro with-temporary-var ((codegen var type) &body body)
382 "Evaluate BODY with VAR bound to a temporary variable name.
384 During BODY, VAR will be marked in-use; when BODY ends, VAR will be marked
385 available for re-use."
386 (multiple-value-bind (doc decls body) (parse-body body :docp nil)
387 (declare (ignore doc))
388 `(let ((,var (temporary-var ,codegen ,type)))
392 (setf (var-in-use-p ,var) nil)))))
394 ;;;--------------------------------------------------------------------------
395 ;;; Code generation idioms.
397 (export 'deliver-expr)
398 (defun deliver-expr (codegen target expr)
399 "Emit code to deliver the value of EXPR to the TARGET.
401 The TARGET may be one of the following.
403 * `:void', indicating that the value is to be discarded. The expression
404 will still be evaluated.
406 * `:void-return', indicating that the value is to be discarded (as for
407 `:void') and furthermore a `return' from the current function should
408 be forced after computing the value.
410 * `:return', indicating that the value is to be returned from the
413 * A variable name, indicating that the value is to be stored in the
416 In the cases of `:return', `:void' and `:void-return' targets, it is valid
417 for EXPR to be nil; this signifies that no computation needs to be
418 performed. Variable-name targets require an expression."
421 (:return (emit-inst codegen (make-return-inst expr)))
422 (:void (when expr (emit-inst codegen (make-expr-inst expr))))
423 (:void-return (when expr (emit-inst codegen (make-expr-inst expr)))
424 (emit-inst codegen (make-return-inst nil)))
425 (t (emit-inst codegen (make-set-inst target expr)))))
427 (export 'convert-stmts)
428 (defun convert-stmts (codegen target type func)
429 "Invoke FUNC to deliver a value to a non-`:return' target.
431 FUNC is a function which accepts a single argument, a non-`:return'
432 target, and generates statements which deliver a value (see
433 `deliver-expr') of the specified TYPE to this target. In general, the
434 generated code will have the form
436 setup instructions...
437 (deliver-expr CODEGEN TARGET (compute value...))
438 cleanup instructions...
440 where the cleanup instructions are essential to the proper working of the
443 The `convert-stmts' function will call FUNC to generate code, and arrange
444 that its value is correctly delivered to TARGET, regardless of what the
445 TARGET is -- i.e., it lifts the restriction to non-`:return' targets. It
446 does this by inventing a new temporary variable."
449 (:return (with-temporary-var (codegen var type)
451 (deliver-expr codegen target var)))
452 (:void-return (funcall func :void)
453 (emit-inst codegen (make-return-inst nil)))
454 (t (funcall func target))))
456 (export 'deliver-call)
457 (defun deliver-call (codegen target func &rest args)
458 "Emit a statement to call FUNC with ARGS and deliver the result to TARGET."
459 (deliver-expr codegen target (apply #'make-call-inst func args)))
461 ;;;----- That's all, folks --------------------------------------------------