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39605a34 | 1 | ;;; cconv.el --- Closure conversion for statically scoped Emacs lisp. -*- lexical-binding: t; coding: utf-8 -*- |
94d11cb5 | 2 | |
d779e73c SM |
3 | ;; Copyright (C) 2011 Free Software Foundation, Inc. |
4 | ||
5 | ;; Author: Igor Kuzmin <kzuminig@iro.umontreal.ca> | |
6 | ;; Maintainer: FSF | |
7 | ;; Keywords: lisp | |
8 | ;; Package: emacs | |
9 | ||
10 | ;; This file is part of GNU Emacs. | |
11 | ||
12 | ;; GNU Emacs 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 3 of the License, or | |
15 | ;; (at your option) any later version. | |
16 | ||
17 | ;; GNU Emacs 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 GNU Emacs. If not, see <http://www.gnu.org/licenses/>. | |
94d11cb5 IK |
24 | |
25 | ;;; Commentary: | |
26 | ||
27 | ;; This takes a piece of Elisp code, and eliminates all free variables from | |
28 | ;; lambda expressions. The user entry points are cconv-closure-convert and | |
c7015153 | 29 | ;; cconv-closure-convert-toplevel (for toplevel forms). |
d779e73c SM |
30 | ;; All macros should be expanded beforehand. |
31 | ;; | |
32 | ;; Here is a brief explanation how this code works. | |
c7015153 | 33 | ;; Firstly, we analyze the tree by calling cconv-analyse-form. |
d779e73c | 34 | ;; This function finds all mutated variables, all functions that are suitable |
94d11cb5 IK |
35 | ;; for lambda lifting and all variables captured by closure. It passes the tree |
36 | ;; once, returning a list of three lists. | |
d779e73c | 37 | ;; |
c7015153 | 38 | ;; Then we calculate the intersection of the first and third lists returned by |
d779e73c SM |
39 | ;; cconv-analyse form to find all mutated variables that are captured by |
40 | ;; closure. | |
94d11cb5 | 41 | |
d779e73c | 42 | ;; Armed with this data, we call cconv-closure-convert-rec, that rewrites the |
c7015153 | 43 | ;; tree recursively, lifting lambdas where possible, building closures where it |
94d11cb5 IK |
44 | ;; is needed and eliminating mutable variables used in closure. |
45 | ;; | |
46 | ;; We do following replacements : | |
47 | ;; (lambda (v1 ...) ... fv1 fv2 ...) => (lambda (v1 ... fv1 fv2 ) ... fv1 fv2 .) | |
48 | ;; if the function is suitable for lambda lifting (if all calls are known) | |
49 | ;; | |
876c194c SM |
50 | ;; (lambda (v0 ...) ... fv0 .. fv1 ...) => |
51 | ;; (internal-make-closure (v0 ...) (fv1 ...) | |
52 | ;; ... (internal-get-closed-var 0) ... (internal-get-closed-var 1) ...) | |
94d11cb5 IK |
53 | ;; |
54 | ;; If the function has no free variables, we don't do anything. | |
94d11cb5 | 55 | ;; |
d779e73c | 56 | ;; If a variable is mutated (updated by setq), and it is used in a closure |
876c194c | 57 | ;; we wrap its definition with list: (list val) and we also replace |
d779e73c SM |
58 | ;; var => (car var) wherever this variable is used, and also |
59 | ;; (setq var value) => (setcar var value) where it is updated. | |
94d11cb5 | 60 | ;; |
d779e73c SM |
61 | ;; If defun argument is closure mutable, we letbind it and wrap it's |
62 | ;; definition with list. | |
63 | ;; (defun foo (... mutable-arg ...) ...) => | |
64 | ;; (defun foo (... m-arg ...) (let ((m-arg (list m-arg))) ...)) | |
94d11cb5 IK |
65 | ;; |
66 | ;;; Code: | |
67 | ||
ca105506 | 68 | ;; TODO: (not just for cconv but also for the lexbind changes in general) |
ca105506 | 69 | ;; - let (e)debug find the value of lexical variables from the stack. |
7200d79c | 70 | ;; - make eval-region do the eval-sexp-add-defvars danse. |
e2abe5a1 | 71 | ;; - byte-optimize-form should be applied before cconv. |
ca105506 SM |
72 | ;; OTOH, the warnings emitted by cconv-analyze need to come before optimize |
73 | ;; since afterwards they can because obnoxious (warnings about an "unused | |
74 | ;; variable" should not be emitted when the variable use has simply been | |
75 | ;; optimized away). | |
7200d79c SM |
76 | ;; - turn defun and defmacro into macros (and remove special handling of |
77 | ;; `declare' afterwards). | |
78 | ;; - let macros specify that some let-bindings come from the same source, | |
79 | ;; so the unused warning takes all uses into account. | |
80 | ;; - let interactive specs return a function to build the args (to stash into | |
81 | ;; command-history). | |
cb9336bd SM |
82 | ;; - canonize code in macro-expand so we don't have to handle (let (var) body) |
83 | ;; and other oddities. | |
3e21b6a7 SM |
84 | ;; - new byte codes for unwind-protect, catch, and condition-case so that |
85 | ;; closures aren't needed at all. | |
7200d79c | 86 | ;; - inline source code of different binding mode by first compiling it. |
d032d5e7 SM |
87 | ;; - a reference to a var that is known statically to always hold a constant |
88 | ;; should be turned into a byte-constant rather than a byte-stack-ref. | |
e2abe5a1 SM |
89 | ;; Hmm... right, that's called constant propagation and could be done here, |
90 | ;; but when that constant is a function, we have to be careful to make sure | |
d032d5e7 SM |
91 | ;; the bytecomp only compiles it once. |
92 | ;; - Since we know here when a variable is not mutated, we could pass that | |
93 | ;; info to the byte-compiler, e.g. by using a new `immutable-let'. | |
e2abe5a1 | 94 | ;; - add tail-calls to bytecode.c and the byte compiler. |
29a4dcb0 | 95 | ;; - call known non-escaping functions with `goto' rather than `call'. |
6c075cd7 | 96 | ;; - optimize mapcar to a while loop. |
d032d5e7 SM |
97 | |
98 | ;; (defmacro dlet (binders &rest body) | |
99 | ;; ;; Works in both lexical and non-lexical mode. | |
100 | ;; `(progn | |
101 | ;; ,@(mapcar (lambda (binder) | |
102 | ;; `(defvar ,(if (consp binder) (car binder) binder))) | |
103 | ;; binders) | |
104 | ;; (let ,binders ,@body))) | |
105 | ||
106 | ;; (defmacro llet (binders &rest body) | |
107 | ;; ;; Only works in lexical-binding mode. | |
108 | ;; `(funcall | |
109 | ;; (lambda ,(mapcar (lambda (binder) (if (consp binder) (car binder) binder)) | |
110 | ;; binders) | |
111 | ;; ,@body) | |
112 | ;; ,@(mapcar (lambda (binder) (if (consp binder) (cadr binder))) | |
113 | ;; binders))) | |
114 | ||
94d11cb5 IK |
115 | (eval-when-compile (require 'cl)) |
116 | ||
d032d5e7 | 117 | (defconst cconv-liftwhen 6 |
d779e73c | 118 | "Try to do lambda lifting if the number of arguments + free variables |
94d11cb5 | 119 | is less than this number.") |
a9de04fa SM |
120 | ;; List of all the variables that are both captured by a closure |
121 | ;; and mutated. Each entry in the list takes the form | |
122 | ;; (BINDER . PARENTFORM) where BINDER is the (VAR VAL) that introduces the | |
123 | ;; variable (or is just (VAR) for variables not introduced by let). | |
124 | (defvar cconv-captured+mutated) | |
d779e73c | 125 | |
a9de04fa SM |
126 | ;; List of candidates for lambda lifting. |
127 | ;; Each candidate has the form (BINDER . PARENTFORM). A candidate | |
128 | ;; is a variable that is only passed to `funcall' or `apply'. | |
129 | (defvar cconv-lambda-candidates) | |
d779e73c | 130 | |
a9de04fa SM |
131 | ;; Alist associating to each function body the list of its free variables. |
132 | (defvar cconv-freevars-alist) | |
94d11cb5 IK |
133 | |
134 | ;;;###autoload | |
295fb2ac SM |
135 | (defun cconv-closure-convert (form) |
136 | "Main entry point for closure conversion. | |
94d11cb5 IK |
137 | -- FORM is a piece of Elisp code after macroexpansion. |
138 | -- TOPLEVEL(optional) is a boolean variable, true if we are at the root of AST | |
139 | ||
140 | Returns a form where all lambdas don't have any free variables." | |
b38b1ec0 | 141 | ;; (message "Entering cconv-closure-convert...") |
a9de04fa | 142 | (let ((cconv-freevars-alist '()) |
94d11cb5 | 143 | (cconv-lambda-candidates '()) |
d779e73c | 144 | (cconv-captured+mutated '())) |
c7015153 | 145 | ;; Analyze form - fill these variables with new information. |
a9de04fa SM |
146 | (cconv-analyse-form form '()) |
147 | (setq cconv-freevars-alist (nreverse cconv-freevars-alist)) | |
6c075cd7 | 148 | (cconv-convert form nil nil))) ; Env initially empty. |
94d11cb5 | 149 | |
295fb2ac | 150 | (defconst cconv--dummy-var (make-symbol "ignored")) |
b38b1ec0 SM |
151 | |
152 | (defun cconv--set-diff (s1 s2) | |
153 | "Return elements of set S1 that are not in set S2." | |
154 | (let ((res '())) | |
155 | (dolist (x s1) | |
156 | (unless (memq x s2) (push x res))) | |
157 | (nreverse res))) | |
158 | ||
159 | (defun cconv--set-diff-map (s m) | |
160 | "Return elements of set S that are not in Dom(M)." | |
161 | (let ((res '())) | |
162 | (dolist (x s) | |
163 | (unless (assq x m) (push x res))) | |
164 | (nreverse res))) | |
165 | ||
166 | (defun cconv--map-diff (m1 m2) | |
167 | "Return the submap of map M1 that has Dom(M2) removed." | |
168 | (let ((res '())) | |
169 | (dolist (x m1) | |
170 | (unless (assq (car x) m2) (push x res))) | |
171 | (nreverse res))) | |
172 | ||
173 | (defun cconv--map-diff-elem (m x) | |
174 | "Return the map M minus any mapping for X." | |
175 | ;; Here we assume that X appears at most once in M. | |
176 | (let* ((b (assq x m)) | |
177 | (res (if b (remq b m) m))) | |
178 | (assert (null (assq x res))) ;; Check the assumption was warranted. | |
179 | res)) | |
94d11cb5 | 180 | |
b38b1ec0 SM |
181 | (defun cconv--map-diff-set (m s) |
182 | "Return the map M minus any mapping for elements of S." | |
183 | ;; Here we assume that X appears at most once in M. | |
184 | (let ((res '())) | |
185 | (dolist (b m) | |
186 | (unless (memq (car b) s) (push b res))) | |
187 | (nreverse res))) | |
188 | ||
6c075cd7 SM |
189 | (defun cconv--convert-function (args body env parentform) |
190 | (assert (equal body (caar cconv-freevars-alist))) | |
191 | (let* ((fvs (cdr (pop cconv-freevars-alist))) | |
192 | (body-new '()) | |
a9de04fa | 193 | (letbind '()) |
6c075cd7 SM |
194 | (envector ()) |
195 | (i 0) | |
196 | (new-env ())) | |
197 | ;; Build the "formal and actual envs" for the closure-converted function. | |
198 | (dolist (fv fvs) | |
199 | (let ((exp (or (cdr (assq fv env)) fv))) | |
200 | (pcase exp | |
201 | ;; If `fv' is a variable that's wrapped in a cons-cell, | |
202 | ;; we want to put the cons-cell itself in the closure, | |
203 | ;; rather than just a copy of its current content. | |
204 | (`(car ,iexp . ,_) | |
205 | (push iexp envector) | |
206 | (push `(,fv . (car (internal-get-closed-var ,i))) new-env)) | |
207 | (_ | |
208 | (push exp envector) | |
209 | (push `(,fv . (internal-get-closed-var ,i)) new-env)))) | |
210 | (setq i (1+ i))) | |
211 | (setq envector (nreverse envector)) | |
212 | (setq new-env (nreverse new-env)) | |
213 | ||
214 | (dolist (arg args) | |
215 | (if (not (member (cons (list arg) parentform) cconv-captured+mutated)) | |
216 | (if (assq arg new-env) (push `(,arg) new-env)) | |
217 | (push `(,arg . (car ,arg)) new-env) | |
218 | (push `(,arg (list ,arg)) letbind))) | |
ca105506 | 219 | |
6c075cd7 SM |
220 | (setq body-new (mapcar (lambda (form) |
221 | (cconv-convert form new-env nil)) | |
222 | body)) | |
223 | ||
224 | (when letbind | |
225 | (let ((special-forms '())) | |
226 | ;; Keep special forms at the beginning of the body. | |
227 | (while (or (stringp (car body-new)) ;docstring. | |
228 | (memq (car-safe (car body-new)) '(interactive declare))) | |
229 | (push (pop body-new) special-forms)) | |
230 | (setq body-new | |
231 | `(,@(nreverse special-forms) (let ,letbind . ,body-new))))) | |
a9de04fa SM |
232 | |
233 | (cond | |
6c075cd7 SM |
234 | ((null envector) ;if no freevars - do nothing |
235 | `(function (lambda ,args . ,body-new))) | |
a9de04fa SM |
236 | (t |
237 | `(internal-make-closure | |
6c075cd7 | 238 | ,args ,envector . ,body-new))))) |
a9de04fa | 239 | |
6c075cd7 | 240 | (defun cconv-convert (form env extend) |
d779e73c | 241 | ;; This function actually rewrites the tree. |
6c075cd7 SM |
242 | "Return FORM with all its lambdas changed so they are closed. |
243 | ENV is a lexical environment mapping variables to the expression | |
244 | used to get its value. This is used for variables that are copied into | |
245 | closures, moved into cons cells, ... | |
246 | ENV is a list where each entry takes the shape either: | |
247 | (VAR . (car EXP)): VAR has been moved into the car of a cons-cell, and EXP | |
248 | is an expression that evaluates to this cons-cell. | |
249 | (VAR . (internal-get-closed-var N)): VAR has been copied into the closure | |
250 | environment's Nth slot. | |
251 | (VAR . (apply-partially F ARG1 ARG2 ..)): VAR has been λ-lifted and takes | |
252 | additional arguments ARGs. | |
253 | EXTEND is a list of variables which might need to be accessed even from places | |
254 | where they are shadowed, because some part of ENV causes them to be used at | |
255 | places where they originally did not directly appear." | |
256 | (assert (not (delq nil (mapcar (lambda (mapping) | |
257 | (if (eq (cadr mapping) 'apply-partially) | |
258 | (cconv--set-diff (cdr (cddr mapping)) | |
259 | extend))) | |
260 | env)))) | |
ca105506 | 261 | |
d779e73c | 262 | ;; What's the difference between fvrs and envs? |
94d11cb5 IK |
263 | ;; Suppose that we have the code |
264 | ;; (lambda (..) fvr (let ((fvr 1)) (+ fvr 1))) | |
d779e73c SM |
265 | ;; only the first occurrence of fvr should be replaced by |
266 | ;; (aref env ...). | |
94d11cb5 IK |
267 | ;; So initially envs and fvrs are the same thing, but when we descend to |
268 | ;; the 'let, we delete fvr from fvrs. Why we don't delete fvr from envs? | |
269 | ;; Because in envs the order of variables is important. We use this list | |
d779e73c SM |
270 | ;; to find the number of a specific variable in the environment vector, |
271 | ;; so we never touch it(unless we enter to the other closure). | |
272 | ;;(if (listp form) (print (car form)) form) | |
273 | (pcase form | |
6c075cd7 | 274 | (`(,(and letsym (or `let* `let)) ,binders . ,body) |
94d11cb5 IK |
275 | |
276 | ; let and let* special forms | |
6c075cd7 SM |
277 | (let ((binders-new '()) |
278 | (new-env env) | |
279 | (new-extend extend)) | |
d779e73c | 280 | |
295fb2ac SM |
281 | (dolist (binder binders) |
282 | (let* ((value nil) | |
283 | (var (if (not (consp binder)) | |
a9de04fa | 284 | (prog1 binder (setq binder (list binder))) |
295fb2ac SM |
285 | (setq value (cadr binder)) |
286 | (car binder))) | |
287 | (new-val | |
288 | (cond | |
289 | ;; Check if var is a candidate for lambda lifting. | |
6c075cd7 SM |
290 | ((and (member (cons binder form) cconv-lambda-candidates) |
291 | (progn | |
292 | (assert (and (eq (car value) 'function) | |
293 | (eq (car (cadr value)) 'lambda))) | |
294 | (assert (equal (cddr (cadr value)) | |
295 | (caar cconv-freevars-alist))) | |
296 | ;; Peek at the freevars to decide whether to λ-lift. | |
297 | (let* ((fvs (cdr (car cconv-freevars-alist))) | |
298 | (fun (cadr value)) | |
299 | (funargs (cadr fun)) | |
300 | (funcvars (append fvs funargs))) | |
94d11cb5 | 301 | ; lambda lifting condition |
6c075cd7 SM |
302 | (and fvs (>= cconv-liftwhen (length funcvars)))))) |
303 | ; Lift. | |
304 | (let* ((fvs (cdr (pop cconv-freevars-alist))) | |
305 | (fun (cadr value)) | |
306 | (funargs (cadr fun)) | |
307 | (funcvars (append fvs funargs)) | |
308 | (funcbody (cddr fun)) | |
309 | (funcbody-env ())) | |
310 | (push `(,var . (apply-partially ,var . ,fvs)) new-env) | |
311 | (dolist (fv fvs) | |
312 | (pushnew fv new-extend) | |
313 | (if (and (eq 'car (car-safe (cdr (assq fv env)))) | |
314 | (not (memq fv funargs))) | |
315 | (push `(,fv . (car ,fv)) funcbody-env))) | |
316 | `(function (lambda ,funcvars . | |
317 | ,(mapcar (lambda (form) | |
318 | (cconv-convert | |
319 | form funcbody-env nil)) | |
320 | funcbody))))) | |
295fb2ac SM |
321 | |
322 | ;; Check if it needs to be turned into a "ref-cell". | |
a9de04fa | 323 | ((member (cons binder form) cconv-captured+mutated) |
295fb2ac | 324 | ;; Declared variable is mutated and captured. |
6c075cd7 SM |
325 | (push `(,var . (car ,var)) new-env) |
326 | `(list ,(cconv-convert value env extend))) | |
295fb2ac SM |
327 | |
328 | ;; Normal default case. | |
329 | (t | |
6c075cd7 SM |
330 | (if (assq var new-env) (push `(,var) new-env)) |
331 | (cconv-convert value env extend))))) | |
332 | ||
333 | ;; The piece of code below letbinds free variables of a λ-lifted | |
334 | ;; function if they are redefined in this let, example: | |
335 | ;; (let* ((fun (lambda (x) (+ x y))) (y 1)) (funcall fun 1)) | |
336 | ;; Here we can not pass y as parameter because it is redefined. | |
337 | ;; So we add a (closed-y y) declaration. We do that even if the | |
338 | ;; function is not used inside this let(*). The reason why we | |
339 | ;; ignore this case is that we can't "look forward" to see if the | |
340 | ;; function is called there or not. To treat this case better we'd | |
341 | ;; need to traverse the tree one more time to collect this data, and | |
342 | ;; I think that it's not worth it. | |
343 | (when (memq var new-extend) | |
344 | (let ((closedsym | |
345 | (make-symbol (concat "closed-" (symbol-name var))))) | |
346 | (setq new-env | |
347 | (mapcar (lambda (mapping) | |
348 | (if (not (eq (cadr mapping) 'apply-partially)) | |
349 | mapping | |
350 | (assert (eq (car mapping) (nth 2 mapping))) | |
351 | (list* (car mapping) | |
352 | 'apply-partially | |
353 | (car mapping) | |
354 | (mapcar (lambda (arg) | |
355 | (if (eq var arg) | |
356 | closedsym arg)) | |
357 | (nthcdr 3 mapping))))) | |
358 | new-env)) | |
359 | (setq new-extend (remq var new-extend)) | |
360 | (push closedsym new-extend) | |
361 | (push `(,closedsym ,var) binders-new))) | |
d779e73c | 362 | |
b38b1ec0 SM |
363 | ;; We push the element after redefined free variables are |
364 | ;; processed. This is important to avoid the bug when free | |
365 | ;; variable and the function have the same name. | |
295fb2ac | 366 | (push (list var new-val) binders-new) |
d779e73c | 367 | |
6c075cd7 SM |
368 | (when (eq letsym 'let*) |
369 | (setq env new-env) | |
370 | (setq extend new-extend)) | |
371 | )) ; end of dolist over binders | |
372 | ||
373 | `(,letsym ,(nreverse binders-new) | |
374 | . ,(mapcar (lambda (form) | |
375 | (cconv-convert | |
376 | form new-env new-extend)) | |
377 | body)))) | |
94d11cb5 IK |
378 | ;end of let let* forms |
379 | ||
d779e73c | 380 | ; first element is lambda expression |
6c075cd7 SM |
381 | (`(,(and `(lambda . ,_) fun) . ,args) |
382 | ;; FIXME: it's silly to create a closure just to call it. | |
ca105506 | 383 | ;; Running byte-optimize-form earlier will resolve this. |
6c075cd7 SM |
384 | `(funcall |
385 | ,(cconv-convert `(function ,fun) env extend) | |
386 | ,@(mapcar (lambda (form) | |
387 | (cconv-convert form env extend)) | |
388 | args))) | |
d779e73c SM |
389 | |
390 | (`(cond . ,cond-forms) ; cond special form | |
6c075cd7 SM |
391 | `(cond . ,(mapcar (lambda (branch) |
392 | (mapcar (lambda (form) | |
393 | (cconv-convert form env extend)) | |
394 | branch)) | |
395 | cond-forms))) | |
d779e73c | 396 | |
6c075cd7 SM |
397 | (`(function (lambda ,args . ,body) . ,_) |
398 | (cconv--convert-function args body env form)) | |
d779e73c | 399 | |
876c194c | 400 | (`(internal-make-closure . ,_) |
6c075cd7 SM |
401 | (byte-compile-report-error |
402 | "Internal error in compiler: cconv called twice?")) | |
876c194c | 403 | |
6c075cd7 SM |
404 | (`(quote . ,_) form) |
405 | (`(function . ,_) form) | |
94d11cb5 IK |
406 | |
407 | ;defconst, defvar | |
6c075cd7 SM |
408 | (`(,(and sym (or `defconst `defvar)) ,definedsymbol . ,forms) |
409 | `(,sym ,definedsymbol | |
410 | . ,(mapcar (lambda (form) (cconv-convert form env extend)) | |
411 | forms))) | |
d779e73c SM |
412 | |
413 | ;defun, defmacro | |
414 | (`(,(and sym (or `defun `defmacro)) | |
6c075cd7 SM |
415 | ,func ,args . ,body) |
416 | (assert (equal body (caar cconv-freevars-alist))) | |
a9de04fa | 417 | (assert (null (cdar cconv-freevars-alist))) |
6c075cd7 SM |
418 | |
419 | (let ((new (cconv--convert-function args body env form))) | |
420 | (pcase new | |
421 | (`(function (lambda ,newargs . ,new-body)) | |
422 | (assert (equal args newargs)) | |
423 | `(,sym ,func ,args . ,new-body)) | |
424 | (t (byte-compile-report-error | |
425 | (format "Internal error in cconv of (%s %s ...)" sym func)))))) | |
94d11cb5 | 426 | |
94d11cb5 | 427 | ;condition-case |
295fb2ac | 428 | (`(condition-case ,var ,protected-form . ,handlers) |
6c075cd7 SM |
429 | (let ((newform (cconv--convert-function |
430 | () (list protected-form) env form))) | |
295fb2ac | 431 | `(condition-case :fun-body ,newform |
876c194c SM |
432 | ,@(mapcar (lambda (handler) |
433 | (list (car handler) | |
6c075cd7 SM |
434 | (cconv--convert-function |
435 | (list (or var cconv--dummy-var)) | |
436 | (cdr handler) env form))) | |
876c194c | 437 | handlers)))) |
295fb2ac SM |
438 | |
439 | (`(,(and head (or `catch `unwind-protect)) ,form . ,body) | |
6c075cd7 SM |
440 | `(,head ,(cconv-convert form env extend) |
441 | :fun-body ,(cconv--convert-function () body env form))) | |
295fb2ac | 442 | |
e0f57e65 SM |
443 | (`(track-mouse . ,body) |
444 | `(track-mouse | |
6c075cd7 | 445 | :fun-body ,(cconv--convert-function () body env form))) |
d779e73c SM |
446 | |
447 | (`(setq . ,forms) ; setq special form | |
6c075cd7 | 448 | (let ((prognlist ())) |
d779e73c | 449 | (while forms |
6c075cd7 SM |
450 | (let* ((sym (pop forms)) |
451 | (sym-new (or (cdr (assq sym env)) sym)) | |
452 | (value (cconv-convert (pop forms) env extend))) | |
453 | (push (pcase sym-new | |
454 | ((pred symbolp) `(setq ,sym-new ,value)) | |
455 | (`(car ,iexp) `(setcar ,iexp ,value)) | |
456 | ;; This "should never happen", but for variables which are | |
457 | ;; mutated+captured+unused, we may end up trying to `setq' | |
458 | ;; on a closed-over variable, so just drop the setq. | |
459 | (_ ;; (byte-compile-report-error | |
460 | ;; (format "Internal error in cconv of (setq %s ..)" | |
461 | ;; sym-new)) | |
462 | value)) | |
463 | prognlist))) | |
d779e73c | 464 | (if (cdr prognlist) |
6c075cd7 | 465 | `(progn . ,(nreverse prognlist)) |
d779e73c SM |
466 | (car prognlist)))) |
467 | ||
468 | (`(,(and (or `funcall `apply) callsym) ,fun . ,args) | |
6c075cd7 SM |
469 | ;; These are not special forms but we treat them separately for the needs |
470 | ;; of lambda lifting. | |
471 | (let ((mapping (cdr (assq fun env)))) | |
472 | (pcase mapping | |
473 | (`(apply-partially ,_ . ,(and fvs `(,_ . ,_))) | |
474 | (assert (eq (cadr mapping) fun)) | |
475 | `(,callsym ,fun | |
476 | ,@(mapcar (lambda (fv) | |
477 | (let ((exp (or (cdr (assq fv env)) fv))) | |
478 | (pcase exp | |
479 | (`(car ,iexp . ,_) iexp) | |
480 | (_ exp)))) | |
481 | fvs) | |
482 | ,@(mapcar (lambda (arg) | |
483 | (cconv-convert arg env extend)) | |
484 | args))) | |
485 | (_ `(,callsym ,@(mapcar (lambda (arg) | |
486 | (cconv-convert arg env extend)) | |
487 | (cons fun args))))))) | |
d779e73c | 488 | |
d032d5e7 | 489 | (`(interactive . ,forms) |
6c075cd7 SM |
490 | `(interactive . ,(mapcar (lambda (form) |
491 | (cconv-convert form nil nil)) | |
492 | forms))) | |
ca105506 | 493 | |
ba83908c | 494 | (`(declare . ,_) form) ;The args don't contain code. |
ca105506 | 495 | |
6c075cd7 SM |
496 | (`(,func . ,forms) |
497 | ;; First element is function or whatever function-like forms are: or, and, | |
498 | ;; if, progn, prog1, prog2, while, until | |
499 | `(,func . ,(mapcar (lambda (form) | |
500 | (cconv-convert form env extend)) | |
501 | forms))) | |
502 | ||
503 | (_ (or (cdr (assq form env)) form)))) | |
43e67019 | 504 | |
a9de04fa SM |
505 | (unless (fboundp 'byte-compile-not-lexical-var-p) |
506 | ;; Only used to test the code in non-lexbind Emacs. | |
507 | (defalias 'byte-compile-not-lexical-var-p 'boundp)) | |
508 | ||
6c075cd7 | 509 | (defun cconv--analyse-use (vardata form varkind) |
e9fce1ac | 510 | "Analyze the use of a variable. |
d032d5e7 SM |
511 | VARDATA should be (BINDER READ MUTATED CAPTURED CALLED). |
512 | VARKIND is the name of the kind of variable. | |
513 | FORM is the parent form that binds this var." | |
a9de04fa SM |
514 | ;; use = `(,binder ,read ,mutated ,captured ,called) |
515 | (pcase vardata | |
d032d5e7 SM |
516 | (`(,_ nil nil nil nil) nil) |
517 | (`((,(and (pred (lambda (var) (eq ?_ (aref (symbol-name var) 0)))) var) . ,_) | |
518 | ,_ ,_ ,_ ,_) | |
6c075cd7 SM |
519 | (byte-compile-log-warning |
520 | (format "%s `%S' not left unused" varkind var)))) | |
d032d5e7 SM |
521 | (pcase vardata |
522 | (`((,var . ,_) nil ,_ ,_ nil) | |
523 | ;; FIXME: This gives warnings in the wrong order, with imprecise line | |
524 | ;; numbers and without function name info. | |
525 | (unless (or ;; Uninterned symbols typically come from macro-expansion, so | |
526 | ;; it is often non-trivial for the programmer to avoid such | |
527 | ;; unused vars. | |
528 | (not (intern-soft var)) | |
e67a13ab CY |
529 | (eq ?_ (aref (symbol-name var) 0)) |
530 | ;; As a special exception, ignore "ignore". | |
531 | (eq var 'ignored)) | |
d032d5e7 SM |
532 | (byte-compile-log-warning (format "Unused lexical %s `%S'" |
533 | varkind var)))) | |
a9de04fa | 534 | ;; If it's unused, there's no point converting it into a cons-cell, even if |
d032d5e7 | 535 | ;; it's captured and mutated. |
a9de04fa SM |
536 | (`(,binder ,_ t t ,_) |
537 | (push (cons binder form) cconv-captured+mutated)) | |
538 | (`(,(and binder `(,_ (function (lambda . ,_)))) nil nil nil t) | |
6c075cd7 | 539 | (push (cons binder form) cconv-lambda-candidates)))) |
a9de04fa | 540 | |
6c075cd7 | 541 | (defun cconv--analyse-function (args body env parentform) |
a9de04fa SM |
542 | (let* ((newvars nil) |
543 | (freevars (list body)) | |
544 | ;; We analyze the body within a new environment where all uses are | |
545 | ;; nil, so we can distinguish uses within that function from uses | |
546 | ;; outside of it. | |
547 | (envcopy | |
548 | (mapcar (lambda (vdata) (list (car vdata) nil nil nil nil)) env)) | |
549 | (newenv envcopy)) | |
550 | ;; Push it before recursing, so cconv-freevars-alist contains entries in | |
551 | ;; the order they'll be used by closure-convert-rec. | |
552 | (push freevars cconv-freevars-alist) | |
553 | (dolist (arg args) | |
554 | (cond | |
555 | ((byte-compile-not-lexical-var-p arg) | |
06788a55 | 556 | (byte-compile-log-warning |
a9de04fa SM |
557 | (format "Argument %S is not a lexical variable" arg))) |
558 | ((eq ?& (aref (symbol-name arg) 0)) nil) ;Ignore &rest, &optional, ... | |
559 | (t (let ((varstruct (list arg nil nil nil nil))) | |
560 | (push (cons (list arg) (cdr varstruct)) newvars) | |
561 | (push varstruct newenv))))) | |
e9fce1ac | 562 | (dolist (form body) ;Analyze body forms. |
a9de04fa SM |
563 | (cconv-analyse-form form newenv)) |
564 | ;; Summarize resulting data about arguments. | |
565 | (dolist (vardata newvars) | |
6c075cd7 | 566 | (cconv--analyse-use vardata parentform "argument")) |
a9de04fa SM |
567 | ;; Transfer uses collected in `envcopy' (via `newenv') back to `env'; |
568 | ;; and compute free variables. | |
569 | (while env | |
570 | (assert (and envcopy (eq (caar env) (caar envcopy)))) | |
571 | (let ((free nil) | |
572 | (x (cdr (car env))) | |
573 | (y (cdr (car envcopy)))) | |
574 | (while x | |
575 | (when (car y) (setcar x t) (setq free t)) | |
576 | (setq x (cdr x) y (cdr y))) | |
577 | (when free | |
578 | (push (caar env) (cdr freevars)) | |
579 | (setf (nth 3 (car env)) t)) | |
580 | (setq env (cdr env) envcopy (cdr envcopy)))))) | |
581 | ||
582 | (defun cconv-analyse-form (form env) | |
583 | "Find mutated variables and variables captured by closure. | |
c7015153 | 584 | Analyze lambdas if they are suitable for lambda lifting. |
d032d5e7 SM |
585 | - FORM is a piece of Elisp code after macroexpansion. |
586 | - ENV is an alist mapping each enclosing lexical variable to its info. | |
a9de04fa SM |
587 | I.e. each element has the form (VAR . (READ MUTATED CAPTURED CALLED)). |
588 | This function does not return anything but instead fills the | |
589 | `cconv-captured+mutated' and `cconv-lambda-candidates' variables | |
590 | and updates the data stored in ENV." | |
94d11cb5 IK |
591 | (pcase form |
592 | ; let special form | |
43e67019 | 593 | (`(,(and (or `let* `let) letsym) ,binders . ,body-forms) |
d779e73c | 594 | |
43e67019 | 595 | (let ((orig-env env) |
a9de04fa | 596 | (newvars nil) |
d779e73c | 597 | (var nil) |
43e67019 SM |
598 | (value nil)) |
599 | (dolist (binder binders) | |
600 | (if (not (consp binder)) | |
d779e73c | 601 | (progn |
43e67019 | 602 | (setq var binder) ; treat the form (let (x) ...) well |
a9de04fa | 603 | (setq binder (list binder)) |
43e67019 SM |
604 | (setq value nil)) |
605 | (setq var (car binder)) | |
606 | (setq value (cadr binder)) | |
607 | ||
a9de04fa | 608 | (cconv-analyse-form value (if (eq letsym 'let*) env orig-env))) |
43e67019 | 609 | |
ce5b520a | 610 | (unless (byte-compile-not-lexical-var-p var) |
a9de04fa SM |
611 | (let ((varstruct (list var nil nil nil nil))) |
612 | (push (cons binder (cdr varstruct)) newvars) | |
613 | (push varstruct env)))) | |
43e67019 | 614 | |
e9fce1ac | 615 | (dolist (form body-forms) ; Analyze body forms. |
a9de04fa | 616 | (cconv-analyse-form form env)) |
43e67019 | 617 | |
a9de04fa | 618 | (dolist (vardata newvars) |
6c075cd7 | 619 | (cconv--analyse-use vardata form "variable")))) |
43e67019 | 620 | |
94d11cb5 | 621 | ; defun special form |
d779e73c | 622 | (`(,(or `defun `defmacro) ,func ,vrs . ,body-forms) |
43e67019 SM |
623 | (when env |
624 | (byte-compile-log-warning | |
625 | (format "Function %S will ignore its context %S" | |
626 | func (mapcar #'car env)) | |
627 | t :warning)) | |
6c075cd7 | 628 | (cconv--analyse-function vrs body-forms nil form)) |
43e67019 SM |
629 | |
630 | (`(function (lambda ,vrs . ,body-forms)) | |
6c075cd7 | 631 | (cconv--analyse-function vrs body-forms env form)) |
ca105506 | 632 | |
43e67019 SM |
633 | (`(setq . ,forms) |
634 | ;; If a local variable (member of env) is modified by setq then | |
635 | ;; it is a mutated variable. | |
d779e73c | 636 | (while forms |
43e67019 | 637 | (let ((v (assq (car forms) env))) ; v = non nil if visible |
a9de04fa SM |
638 | (when v (setf (nth 2 v) t))) |
639 | (cconv-analyse-form (cadr forms) env) | |
43e67019 SM |
640 | (setq forms (cddr forms)))) |
641 | ||
642 | (`((lambda . ,_) . ,_) ; first element is lambda expression | |
d779e73c | 643 | (dolist (exp `((function ,(car form)) . ,(cdr form))) |
a9de04fa | 644 | (cconv-analyse-form exp env))) |
d779e73c SM |
645 | |
646 | (`(cond . ,cond-forms) ; cond special form | |
43e67019 | 647 | (dolist (forms cond-forms) |
d032d5e7 | 648 | (dolist (form forms) (cconv-analyse-form form env)))) |
d779e73c SM |
649 | |
650 | (`(quote . ,_) nil) ; quote form | |
d779e73c SM |
651 | (`(function . ,_) nil) ; same as quote |
652 | ||
43e67019 SM |
653 | (`(condition-case ,var ,protected-form . ,handlers) |
654 | ;; FIXME: The bytecode for condition-case forces us to wrap the | |
ca105506 SM |
655 | ;; form and handlers in closures (for handlers, it's understandable |
656 | ;; but not for the protected form). | |
6c075cd7 | 657 | (cconv--analyse-function () (list protected-form) env form) |
43e67019 | 658 | (dolist (handler handlers) |
6c075cd7 | 659 | (cconv--analyse-function (if var (list var)) (cdr handler) env form))) |
43e67019 SM |
660 | |
661 | ;; FIXME: The bytecode for catch forces us to wrap the body. | |
662 | (`(,(or `catch `unwind-protect) ,form . ,body) | |
a9de04fa | 663 | (cconv-analyse-form form env) |
6c075cd7 | 664 | (cconv--analyse-function () body env form)) |
43e67019 | 665 | |
ca105506 SM |
666 | ;; FIXME: The lack of bytecode for track-mouse forces us to wrap the body. |
667 | ;; `track-mouse' really should be made into a macro. | |
e0f57e65 | 668 | (`(track-mouse . ,body) |
6c075cd7 | 669 | (cconv--analyse-function () body env form)) |
43e67019 SM |
670 | |
671 | (`(,(or `defconst `defvar) ,var ,value . ,_) | |
672 | (push var byte-compile-bound-variables) | |
a9de04fa | 673 | (cconv-analyse-form value env)) |
d779e73c SM |
674 | |
675 | (`(,(or `funcall `apply) ,fun . ,args) | |
43e67019 SM |
676 | ;; Here we ignore fun because funcall and apply are the only two |
677 | ;; functions where we can pass a candidate for lambda lifting as | |
678 | ;; argument. So, if we see fun elsewhere, we'll delete it from | |
679 | ;; lambda candidate list. | |
a9de04fa SM |
680 | (let ((fdata (and (symbolp fun) (assq fun env)))) |
681 | (if fdata | |
682 | (setf (nth 4 fdata) t) | |
683 | (cconv-analyse-form fun env))) | |
d032d5e7 SM |
684 | (dolist (form args) (cconv-analyse-form form env))) |
685 | ||
686 | (`(interactive . ,forms) | |
687 | ;; These appear within the function body but they don't have access | |
688 | ;; to the function's arguments. | |
689 | ;; We could extend this to allow interactive specs to refer to | |
690 | ;; variables in the function's enclosing environment, but it doesn't | |
691 | ;; seem worth the trouble. | |
692 | (dolist (form forms) (cconv-analyse-form form nil))) | |
ba83908c SM |
693 | |
694 | (`(declare . ,_) nil) ;The args don't contain code. | |
ca105506 | 695 | |
43e67019 | 696 | (`(,_ . ,body-forms) ; First element is a function or whatever. |
d032d5e7 | 697 | (dolist (form body-forms) (cconv-analyse-form form env))) |
43e67019 SM |
698 | |
699 | ((pred symbolp) | |
700 | (let ((dv (assq form env))) ; dv = declared and visible | |
701 | (when dv | |
a9de04fa | 702 | (setf (nth 1 dv) t)))))) |
94d11cb5 IK |
703 | |
704 | (provide 'cconv) | |
705 | ;;; cconv.el ends here |