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1 | ;;; -*-lisp-*- |
2 | ;;; | |
3 | ;;; Code generator for effective methods | |
4 | ;;; | |
5 | ;;; (c) 2009 Straylight/Edgeware | |
6 | ;;; | |
7 | ||
8 | ;;;----- Licensing notice --------------------------------------------------- | |
9 | ;;; | |
10 | ;;; This file is part of the Simple Object Definition system. | |
11 | ;;; | |
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. | |
16 | ;;; | |
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. | |
21 | ;;; | |
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. | |
25 | ||
26 | (cl:in-package #:sod) | |
27 | ||
28 | ;;;-------------------------------------------------------------------------- | |
29 | ;;; Temporary names. | |
30 | ||
31 | (defclass temporary-name () | |
32 | ((tag :initarg :tag :reader temp-tag)) | |
33 | (:documentation | |
34 | "Base class for temporary variable and argument names.")) | |
35 | ||
36 | (defclass temporary-argument (temporary-name) ()) | |
37 | (defclass temporary-function (temporary-name) ()) | |
38 | ||
39 | (defclass temporary-variable (temporary-name) | |
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40 | ((in-use-p :initarg :in-use-p :initform nil |
41 | :type boolean :accessor var-in-use-p))) | |
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42 | |
43 | (defmethod var-in-use-p ((var t)) | |
44 | "Non-temporary variables are always in use." | |
45 | t) | |
46 | ||
47 | (defmethod commentify-argument-name ((name temporary-name)) | |
48 | nil) | |
49 | ||
50 | (defparameter *temporary-index* 0 | |
51 | "Index for temporary name generation. | |
52 | ||
53 | This is automatically reset to zero before the output functions are | |
54 | invoked to write a file. This way, we can ensure that the same output | |
55 | file is always produced from the same input.") | |
56 | ||
57 | (defun temporary-function () | |
58 | "Return a temporary function name." | |
59 | (make-instance 'temporary-function | |
60 | :tag (prog1 *temporary-index* (incf *temporary-index*)))) | |
61 | ||
62 | (defgeneric format-temporary-name (var stream) | |
63 | (:method ((var temporary-name) stream) | |
64 | (format stream "~A" (temp-tag var))) | |
65 | (:method ((var temporary-argument) stream) | |
66 | (format stream "sod__a~A" (temp-tag var))) | |
67 | (:method ((var temporary-variable) stream) | |
68 | (format stream "sod__v~A" (temp-tag var))) | |
69 | (:method ((var temporary-function) stream) | |
70 | (format stream "sod__f~A" (temp-tag var)))) | |
71 | ||
72 | (defmethod print-object ((var temporary-name) stream) | |
73 | (if *print-escape* | |
74 | (print-unreadable-object (var stream :type t) | |
75 | (prin1 (temp-tag var) stream)) | |
76 | (format-temporary-name var stream))) | |
77 | ||
78 | (defparameter *sod-ap* | |
79 | (make-instance 'temporary-name :tag "sod__ap")) | |
80 | (defparameter *sod-master-ap* | |
81 | (make-instance 'temporary-name :tag "sod__master_ap")) | |
82 | ||
83 | ;;;-------------------------------------------------------------------------- | |
84 | ;;; Instructions. | |
85 | ||
86 | (defclass inst () () | |
87 | (:documentation | |
88 | "A base class for instructions. | |
89 | ||
90 | An `instruction' is anything which might be useful to string into a code | |
91 | generator. Both statements and expressions map can be represented by | |
92 | trees of instructions. The DEFINST macro is a convenient way of defining | |
93 | new instructions. | |
94 | ||
95 | The only important protocol for instructions is output, which is achieved | |
96 | by calling PRINT-OBJECT with *PRINT-ESCAPE* nil. | |
97 | ||
98 | This doesn't really do very much, but it acts as a handy marker for | |
99 | instruction subclasses.")) | |
100 | ||
101 | (defgeneric inst-metric (inst) | |
102 | (:documentation | |
103 | "Returns a `metric' describing how complicated INST is. | |
104 | ||
105 | The default metric of an inst node is simply 1; INST subclasses generated | |
106 | by DEFINST (q.v.) have an automatically generated method which returns one | |
107 | plus the sum of the metrics of the node's children. | |
108 | ||
109 | This isn't intended to be a particularly rigorous definition. Its purpose | |
110 | is to allow code generators to make decisions about inlining or calling | |
111 | code fairly simply.") | |
112 | (:method (inst) 1)) | |
113 | ||
114 | (defmacro definst (code (streamvar) args &body body) | |
115 | "Define an instruction type and describe how to output it. | |
116 | ||
117 | An INST can represent any structured piece of output syntax: a statement, | |
118 | expression or declaration, for example. This macro defines the following | |
119 | things: | |
120 | ||
121 | * A class CODE-INST to represent the instruction. | |
122 | ||
123 | * Instance slots named after the ARGS, with matching keyword initargs, | |
124 | and INST-ARG readers. | |
125 | ||
126 | * A constructor MAKE-CODE-INST which accepts the ARGS (in order, not | |
127 | with keywords) as arguments and returns a fresh instance. | |
128 | ||
129 | * A print method, which prints a diagnostic dump if *PRINT-ESCAPE* is | |
130 | set, or invokes the BODY (with STREAMVAR bound to the output stream) | |
131 | otherwise. The BODY is expected to produce target code at this | |
132 | point." | |
133 | ||
134 | (let ((inst-var (gensym "INST")) | |
135 | (class-name (symbolicate code '-inst)) | |
136 | (keys (mapcar (lambda (arg) (intern (symbol-name arg) :keyword)) | |
137 | args))) | |
138 | `(progn | |
139 | (defclass ,class-name (inst) | |
140 | ,(mapcar (lambda (arg key) | |
141 | `(,arg :initarg ,key :reader ,(symbolicate 'inst- arg))) | |
142 | args keys)) | |
143 | (defun ,(symbolicate 'make- code '-inst) (,@args) | |
144 | (make-instance ',class-name ,@(mappend #'list keys args))) | |
145 | (defmethod inst-metric ((,inst-var ,class-name)) | |
146 | (with-slots (,@args) ,inst-var | |
147 | (+ 1 ,@(mapcar (lambda (arg) `(inst-metric ,arg)) args)))) | |
148 | (defmethod print-object ((,inst-var ,class-name) ,streamvar) | |
149 | (with-slots (,@args) ,inst-var | |
150 | (if *print-escape* | |
151 | (print-unreadable-object (,inst-var ,streamvar :type t) | |
152 | (format stream "~@<~@{~S ~@_~S~^ ~_~}~:>" | |
153 | ,@(mappend #'list keys args))) | |
154 | (progn ,@body))))))) | |
155 | ||
156 | (defun format-compound-statement* (stream child morep thunk) | |
157 | "Underlying function for FORMAT-COMPOUND-STATEMENT." | |
158 | (cond ((typep child 'block-inst) | |
159 | (funcall thunk stream) | |
160 | (write-char #\space stream) | |
161 | (princ child stream) | |
162 | (when morep (write-char #\space stream))) | |
163 | (t | |
164 | (pprint-logical-block (stream nil) | |
165 | (funcall thunk stream) | |
166 | (write-char #\space stream) | |
167 | (pprint-indent :block 2 stream) | |
168 | (pprint-newline :linear stream) | |
169 | (princ child stream) | |
170 | (pprint-indent :block 0 stream) | |
171 | (case morep | |
172 | (:space | |
173 | (write-char #\space stream) | |
174 | (pprint-newline :linear stream)) | |
175 | (t | |
176 | (pprint-newline :mandatory stream))))))) | |
177 | ||
178 | (defmacro format-compound-statement | |
179 | ((stream child &optional morep) &body body) | |
180 | "Format a compound statement to STREAM. | |
181 | ||
182 | The introductory material is printed by BODY. The CHILD is formatted | |
183 | properly according to whether it's a BLOCK-INST. If MOREP is true, then | |
184 | allow for more stuff following the child." | |
185 | `(format-compound-statement* ,stream ,child ,morep | |
186 | (lambda (,stream) ,@body))) | |
187 | ||
188 | ;;;-------------------------------------------------------------------------- | |
189 | ;;; Instruction types. | |
190 | ||
191 | ;; Compound statements. | |
192 | ||
193 | (definst block (stream) (decls body) | |
194 | (format stream "{~:@_~@< ~2I~@[~{~A;~:@_~}~:@_~]~{~A~^~:@_~}~:>~:@_}" | |
195 | decls body)) | |
196 | ||
197 | (definst if (stream) (condition consequent alternative) | |
198 | (format-compound-statement (stream consequent alternative) | |
199 | (format stream "if (~A)" condition)) | |
200 | (when alternative | |
201 | (format-compound-statement (stream alternative) | |
202 | (write-string "else" stream)))) | |
203 | ||
204 | (definst while (stream) (condition body) | |
205 | (format-compound-statement (stream body) | |
206 | (format stream "while (~A)" condition))) | |
207 | ||
208 | (definst do-while (stream) (body condition) | |
209 | (format-compound-statement (stream body :space) | |
210 | (write-string "do" stream)) | |
211 | (format stream "while (~A);" condition)) | |
212 | ||
213 | ;; Simple statements. | |
214 | ||
215 | (definst set (stream) (var expr) | |
216 | (format stream "~@<~A = ~@_~2I~A;~:>" var expr)) | |
217 | ||
218 | (definst return (stream) (expr) | |
219 | (format stream "return~@[ (~A)~];" expr)) | |
220 | ||
221 | (definst expr (stream) (expr) | |
222 | (format stream "~A;" expr)) | |
223 | ||
224 | ;; Special varargs hacks. | |
225 | ||
226 | (definst va-start (stream) (ap arg) | |
227 | (format stream "va_start(~@<~A, ~_~A~:>);" ap arg)) | |
228 | ||
229 | (definst va-copy (stream) (to from) | |
230 | (format stream "va_copy(~@<~A, ~_~A~:>);" to from)) | |
231 | ||
232 | (definst va-end (stream) (ap) | |
233 | (format stream "va_end(~A);" ap)) | |
234 | ||
235 | ;; Declarations. These should appear at the heads of BLOCK-INSTs. | |
236 | ||
237 | (definst var (stream) (name type init) | |
238 | (pprint-c-type type stream name) | |
239 | (when init | |
240 | (format stream " = ~A" init))) | |
241 | ||
242 | ;; Expressions. | |
243 | ||
244 | (definst call (stream) (func args) | |
245 | (format stream "~A(~@<~{~A~^, ~_~}~:>)" func args)) | |
246 | ||
247 | ;; Top level things. | |
248 | ||
249 | (definst function (stream) (name type body) | |
250 | (pprint-logical-block (stream nil) | |
251 | (pprint-c-type type stream name) | |
252 | (format stream "~:@_~A~:@_~:@_" body))) | |
253 | ||
254 | ;;;-------------------------------------------------------------------------- | |
255 | ;;; Code generator objects. | |
256 | ||
257 | (defclass basic-codegen () | |
258 | ((vars :initarg :vars :initform nil :type list :accessor codegen-vars) | |
259 | (insts :initarg :insts :initform nil :type list :accessor codegen-insts) | |
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260 | (temp-index :initarg :temp-index :initform 0 |
261 | :type fixnum :accessor codegen-temp-index)) | |
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262 | (:documentation |
263 | "Base class for code generator state. | |
264 | ||
265 | This contains the bare essentials for supporting the EMIT-INST and | |
266 | ENSURE-VAR protocols; see the documentation for those generic functions | |
267 | for more details. | |
268 | ||
269 | This class isn't abstract. A full CODEGEN object uses instances of this | |
270 | to keep track of pending functions which haven't been completed yet. | |
271 | ||
272 | Just in case that wasn't clear enough: this is nothing to do with the | |
273 | BASIC language.")) | |
274 | ||
275 | (defgeneric emit-inst (codegen inst) | |
276 | (:documentation | |
277 | "Add INST to the end of CODEGEN's list of instructions.") | |
278 | (:method ((codegen basic-codegen) inst) | |
279 | (push inst (codegen-insts codegen)))) | |
280 | ||
281 | (defgeneric emit-insts (codegen insts) | |
282 | (:documentation | |
283 | "Add a list of INSTS to the end of CODEGEN's list of instructions.") | |
284 | (:method ((codegen basic-codegen) insts) | |
285 | (setf (codegen-insts codegen) | |
286 | (revappend insts (codegen-insts codegen))))) | |
287 | ||
288 | (defgeneric ensure-var (codegen name type &optional init) | |
289 | (:documentation | |
290 | "Add a variable to CODEGEN's list. | |
291 | ||
292 | The variable is called NAME (which should be comparable using EQUAL and | |
293 | print to an identifier) and has the given TYPE. If INIT is present and | |
294 | non-nil it is an expression INST used to provide the variable with an | |
295 | initial value.") | |
296 | (:method ((codegen basic-codegen) name type &optional init) | |
297 | (let* ((vars (codegen-vars codegen)) | |
298 | (var (find name vars :key #'inst-name :test #'equal))) | |
299 | (cond ((not var) | |
300 | (setf (codegen-vars codegen) | |
301 | (cons (make-var-inst name type init) vars))) | |
302 | ((not (c-type-equal-p type (inst-type var))) | |
303 | (error "(Internal) Redefining type for variable ~A." name))) | |
304 | name))) | |
305 | ||
306 | (defclass codegen (basic-codegen) | |
307 | ((functions :initform nil :type list :accessor codegen-functions) | |
308 | (stack :initform nil :type list :accessor codegen-stack)) | |
309 | (:documentation | |
310 | "A full-fat code generator which can generate and track functions. | |
311 | ||
312 | This is the real deal. Subclasses may which to attach additional state | |
313 | for convenience's sake, but this class is self-contained. It supports the | |
314 | CODEGEN-PUSH, CODEGEN-POP and CODEGEN-POP-FUNCTION protocols.")) | |
315 | ||
316 | (defgeneric codegen-push (codegen) | |
317 | (:documentation | |
318 | "Pushes the current code generation state onto a stack. | |
319 | ||
320 | The state consists of the accumulated variables and instructions, i.e., | |
321 | what is representable by a BASIC-CODEGEN.") | |
322 | (:method ((codegen codegen)) | |
323 | (with-slots (vars insts temp-index stack) codegen | |
324 | (push (make-instance 'basic-codegen | |
325 | :vars vars | |
326 | :insts insts | |
327 | :temp-index temp-index) | |
328 | stack) | |
329 | (setf vars nil insts nil temp-index 0)))) | |
330 | ||
331 | (defgeneric codegen-pop (codegen) | |
332 | (:documentation | |
333 | "Pops a saved state off of the CODEGEN's stack. | |
334 | ||
335 | Returns the newly accumulated variables and instructions as lists, as | |
336 | separate values.") | |
337 | (:method ((codegen codegen)) | |
338 | (with-slots (vars insts temp-index stack) codegen | |
339 | (multiple-value-prog1 | |
340 | (values (nreverse vars) (nreverse insts)) | |
341 | (let ((sub (pop stack))) | |
342 | (setf vars (codegen-vars sub) | |
343 | insts (codegen-insts sub) | |
344 | temp-index (codegen-temp-index sub))))))) | |
345 | ||
346 | (defgeneric codegen-add-function (codegen function) | |
347 | (:documentation | |
348 | "Adds a function to CODEGEN's list. | |
349 | ||
350 | Actually, we're not picky: FUNCTION can be any kind of object that you're | |
351 | willing to find in the list returned by CODEGEN-FUNCTIONS.") | |
352 | (:method ((codegen codegen) function) | |
353 | (with-slots (functions) codegen | |
354 | (setf functions (nconc functions (list function)))))) | |
355 | ||
356 | (defun codegen-build-function (codegen name type vars insts) | |
357 | "Build a function and add it to CODEGEN's list. | |
358 | ||
359 | Returns the function's name." | |
360 | (codegen-add-function codegen | |
361 | (make-function-inst name type | |
362 | (make-block-inst vars insts))) | |
363 | name) | |
364 | ||
365 | (defgeneric codegen-pop-function (codegen name type) | |
366 | (:documentation | |
367 | "Makes a function out of the completed code in CODEGEN. | |
368 | ||
369 | The NAME can be any object you like. The TYPE should be a function type | |
370 | object which includes argument names. The return value is the NAME.") | |
371 | (:method ((codegen codegen) name type) | |
372 | (multiple-value-bind (vars insts) (codegen-pop codegen) | |
373 | (codegen-build-function codegen name type vars insts)))) | |
374 | ||
375 | (defgeneric temporary-var (codegen type) | |
376 | (:documentation | |
377 | "Return the name of a temporary variable. | |
378 | ||
379 | The temporary variable will have the given TYPE, and will be marked | |
380 | in-use. You should clear the in-use flag explicitly when you've finished | |
381 | with the variable -- or, better, use WITH-TEMPORARY-VAR to do the cleanup | |
382 | automatically.")) | |
383 | ||
384 | (defmethod temporary-var ((codegen basic-codegen) type) | |
385 | (with-slots (vars temp-index) codegen | |
386 | (or (find-if (lambda (var) | |
387 | (and (not (var-in-use-p (inst-name var))) | |
388 | (c-type-equal-p type (inst-type var)))) | |
389 | vars) | |
390 | (let* ((name (make-instance 'temporary-variable | |
391 | :tag (prog1 temp-index | |
392 | (incf temp-index))))) | |
393 | (push (make-var-inst name type nil) vars) | |
394 | name)))) | |
395 | ||
396 | (defmacro with-temporary-var ((codegen var type) &body body) | |
397 | "Evaluate BODY with VAR bound to a temporary variable name. | |
398 | ||
399 | During BODY, VAR will be marked in-use; when BODY ends, VAR will be marked | |
400 | available for re-use." | |
401 | `(let ((,var (temporary-var ,codegen ,type))) | |
402 | (unwind-protect | |
403 | (progn ,@body) | |
404 | (setf (var-in-use-p ,var) nil)))) | |
405 | ||
406 | ;;;-------------------------------------------------------------------------- | |
407 | ;;; Code generation idioms. | |
408 | ||
409 | (defun deliver-expr (codegen target expr) | |
410 | "Emit code to deliver the value of EXPR to the TARGET. | |
411 | ||
412 | The TARGET may be one of the following. | |
413 | ||
414 | * :VOID, indicating that the value is to be discarded. The expression | |
415 | will still be evaluated. | |
416 | ||
417 | * :VOID-RETURN, indicating that the value is to be discarded (as for | |
418 | :VOID) and furthermore a `return' from the current function should be | |
419 | forced after computing the value. | |
420 | ||
421 | * :RETURN, indicating that the value is to be returned from the current | |
422 | function. | |
423 | ||
424 | * A variable name, indicating that the value is to be stored in the | |
425 | variable. | |
426 | ||
427 | In the cases of :RETURN, :VOID and :VOID-RETURN targets, it is valid for | |
428 | EXPR to be nil; this signifies that no computation needs to be performed. | |
429 | Variable-name targets require an expression." | |
430 | ||
431 | (case target | |
432 | (:return (emit-inst codegen (make-return-inst expr))) | |
433 | (:void (when expr (emit-inst codegen (make-expr-inst expr)))) | |
434 | (:void-return (when expr (emit-inst codegen (make-expr-inst expr))) | |
435 | (emit-inst codegen (make-return-inst nil))) | |
436 | (t (emit-inst codegen (make-set-inst target expr))))) | |
437 | ||
438 | (defun convert-stmts (codegen target type func) | |
439 | "Invoke FUNC to deliver a value to a non-:RETURN target. | |
440 | ||
441 | FUNC is a function which accepts a single argument, a non-:RETURN target, | |
442 | and generates statements which deliver a value (see DELIVER-EXPR) of the | |
443 | specified TYPE to this target. In general, the generated code will have | |
444 | the form | |
445 | ||
446 | setup instructions... | |
447 | (DELIVER-EXPR CODEGEN TARGET (compute value...)) | |
448 | cleanup instructions... | |
449 | ||
450 | where the cleanup instructions are essential to the proper working of the | |
451 | generated program. | |
452 | ||
453 | CONVERT-STMTS will call FUNC to generate code, and arrange that its value | |
454 | is correctly delivered to TARGET, regardless of what the TARGET is -- | |
455 | i.e., it lifts the restriction to non-:RETURN targets. It does this by | |
456 | inventing a new temporary variable." | |
457 | ||
458 | (case target | |
459 | (:return (with-temporary-var (codegen var type) | |
460 | (funcall func var) | |
461 | (deliver-expr codegen target var))) | |
462 | (:void-return (funcall func :void) | |
463 | (emit-inst codegen (make-return-inst nil))) | |
464 | (t (funcall func target)))) | |
465 | ||
466 | ;;;----- That's all, folks -------------------------------------------------- |