1 ;;; cconv.el --- Closure conversion for statically scoped Emacs lisp. -*- lexical-binding: t; coding: utf-8 -*-
3 ;; Copyright (C) 2011 Free Software Foundation, Inc.
5 ;; Author: Igor Kuzmin <kzuminig@iro.umontreal.ca>
10 ;; This file is part of GNU Emacs.
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.
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.
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/>.
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
29 ;; cconv-closure-convert-toplevel(for toplevel forms).
30 ;; All macros should be expanded beforehand.
32 ;; Here is a brief explanation how this code works.
33 ;; Firstly, we analyse the tree by calling cconv-analyse-form.
34 ;; This function finds all mutated variables, all functions that are suitable
35 ;; for lambda lifting and all variables captured by closure. It passes the tree
36 ;; once, returning a list of three lists.
38 ;; Then we calculate the intersection of first and third lists returned by
39 ;; cconv-analyse form to find all mutated variables that are captured by
42 ;; Armed with this data, we call cconv-closure-convert-rec, that rewrites the
43 ;; tree recursivly, lifting lambdas where possible, building closures where it
44 ;; is needed and eliminating mutable variables used in closure.
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)
50 ;; (lambda (v0 ...) ... fv0 .. fv1 ...) =>
51 ;; (internal-make-closure (v0 ...) (fv1 ...)
52 ;; ... (internal-get-closed-var 0) ... (internal-get-closed-var 1) ...)
54 ;; If the function has no free variables, we don't do anything.
56 ;; If a variable is mutated (updated by setq), and it is used in a closure
57 ;; we wrap its definition with list: (list val) and we also replace
58 ;; var => (car var) wherever this variable is used, and also
59 ;; (setq var value) => (setcar var value) where it is updated.
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))) ...))
69 ;; - byte-optimize-form should be applied before cconv.
70 ;; - maybe unify byte-optimize and compiler-macros.
71 ;; - canonize code in macro-expand so we don't have to handle (let (var) body)
72 ;; and other oddities.
73 ;; - clean up cconv-closure-convert-rec, especially the `let' binding part.
74 ;; - new byte codes for unwind-protect, catch, and condition-case so that
75 ;; closures aren't needed at all.
76 ;; - a reference to a var that is known statically to always hold a constant
77 ;; should be turned into a byte-constant rather than a byte-stack-ref.
78 ;; Hmm... right, that's called constant propagation and could be done here,
79 ;; but when that constant is a function, we have to be careful to make sure
80 ;; the bytecomp only compiles it once.
81 ;; - Since we know here when a variable is not mutated, we could pass that
82 ;; info to the byte-compiler, e.g. by using a new `immutable-let'.
83 ;; - add tail-calls to bytecode.c and the byte compiler.
85 ;; (defmacro dlet (binders &rest body)
86 ;; ;; Works in both lexical and non-lexical mode.
88 ;; ,@(mapcar (lambda (binder)
89 ;; `(defvar ,(if (consp binder) (car binder) binder)))
91 ;; (let ,binders ,@body)))
93 ;; (defmacro llet (binders &rest body)
94 ;; ;; Only works in lexical-binding mode.
96 ;; (lambda ,(mapcar (lambda (binder) (if (consp binder) (car binder) binder))
99 ;; ,@(mapcar (lambda (binder) (if (consp binder) (cadr binder)))
102 ;; (defmacro letrec (binders &rest body)
103 ;; ;; Only useful in lexical-binding mode.
104 ;; ;; As a special-form, we could implement it more efficiently (and cleanly,
105 ;; ;; making the vars actually unbound during evaluation of the binders).
106 ;; `(let ,(mapcar (lambda (binder) (if (consp binder) (car binder) binder))
108 ;; ,@(delq nil (mapcar (lambda (binder) (if (consp binder) `(setq ,@binder)))
112 (eval-when-compile (require 'cl
))
114 (defconst cconv-liftwhen
6
115 "Try to do lambda lifting if the number of arguments + free variables
116 is less than this number.")
117 ;; List of all the variables that are both captured by a closure
118 ;; and mutated. Each entry in the list takes the form
119 ;; (BINDER . PARENTFORM) where BINDER is the (VAR VAL) that introduces the
120 ;; variable (or is just (VAR) for variables not introduced by let).
121 (defvar cconv-captured
+mutated
)
123 ;; List of candidates for lambda lifting.
124 ;; Each candidate has the form (BINDER . PARENTFORM). A candidate
125 ;; is a variable that is only passed to `funcall' or `apply'.
126 (defvar cconv-lambda-candidates
)
128 ;; Alist associating to each function body the list of its free variables.
129 (defvar cconv-freevars-alist
)
132 (defun cconv-closure-convert (form)
133 "Main entry point for closure conversion.
134 -- FORM is a piece of Elisp code after macroexpansion.
135 -- TOPLEVEL(optional) is a boolean variable, true if we are at the root of AST
137 Returns a form where all lambdas don't have any free variables."
138 ;; (message "Entering cconv-closure-convert...")
139 (let ((cconv-freevars-alist '())
140 (cconv-lambda-candidates '())
141 (cconv-captured+mutated
'()))
142 ;; Analyse form - fill these variables with new information.
143 (cconv-analyse-form form
'())
144 (setq cconv-freevars-alist
(nreverse cconv-freevars-alist
))
145 (cconv-closure-convert-rec
148 '() ; fvrs initially empty
149 '() ; envs initially empty
153 (defconst cconv--dummy-var
(make-symbol "ignored"))
155 (defun cconv--set-diff (s1 s2
)
156 "Return elements of set S1 that are not in set S2."
159 (unless (memq x s2
) (push x res
)))
162 (defun cconv--set-diff-map (s m
)
163 "Return elements of set S that are not in Dom(M)."
166 (unless (assq x m
) (push x res
)))
169 (defun cconv--map-diff (m1 m2
)
170 "Return the submap of map M1 that has Dom(M2) removed."
173 (unless (assq (car x
) m2
) (push x res
)))
176 (defun cconv--map-diff-elem (m x
)
177 "Return the map M minus any mapping for X."
178 ;; Here we assume that X appears at most once in M.
179 (let* ((b (assq x m
))
180 (res (if b
(remq b m
) m
)))
181 (assert (null (assq x res
))) ;; Check the assumption was warranted.
184 (defun cconv--map-diff-set (m s
)
185 "Return the map M minus any mapping for elements of S."
186 ;; Here we assume that X appears at most once in M.
189 (unless (memq (car b
) s
) (push b res
)))
192 (defun cconv-closure-convert-function (fvrs vars emvrs envs lmenvs body-forms
194 (assert (equal body-forms
(caar cconv-freevars-alist
)))
195 (let* ((fvrs-new (cconv--set-diff fvrs vars
)) ; Remove vars from fvrs.
196 (fv (cdr (pop cconv-freevars-alist
)))
201 ;; Here we form our environment vector.
205 (cconv-closure-convert-rec
206 ;; Remove `elm' from `emvrs' for this call because in case
207 ;; `elm' is a variable that's wrapped in a cons-cell, we
208 ;; want to put the cons-cell itself in the closure, rather
209 ;; than just a copy of its current content.
210 elm
(remq elm emvrs
) fvrs envs lmenvs
)
211 envector
)) ; Process vars for closure vector.
212 (setq envector
(reverse envector
))
214 (setq fvrs-new fv
)) ; Update substitution list.
216 (setq emvrs
(cconv--set-diff emvrs vars
))
217 (setq lmenvs
(cconv--map-diff-set lmenvs vars
))
219 ;; The difference between envs and fvrs is explained
220 ;; in comment in the beginning of the function.
222 (when (member (cons (list var
) parentform
) cconv-captured
+mutated
)
224 (push `(,var
(list ,var
)) letbind
)))
225 (dolist (elm body-forms
) ; convert function body
226 (push (cconv-closure-convert-rec
227 elm emvrs fvrs-new envs lmenvs
)
231 (if letbind
`((let ,letbind .
,(reverse body-forms-new
)))
232 (reverse body-forms-new
)))
235 ;if no freevars - do nothing
237 `(function (lambda ,vars .
,body-forms-new
)))
238 ; 1 free variable - do not build vector
240 `(internal-make-closure
241 ,vars
,envector .
,body-forms-new
)))))
243 (defun cconv-closure-convert-rec (form emvrs fvrs envs lmenvs
)
244 ;; This function actually rewrites the tree.
245 "Eliminates all free variables of all lambdas in given forms.
247 - FORM is a piece of Elisp code after macroexpansion.
248 - LMENVS is a list of environments used for lambda-lifting. Initially empty.
249 - EMVRS is a list that contains mutated variables that are visible
250 within current environment.
251 - ENVS is an environment(list of free variables) of current closure.
253 - FVRS is a list of variables to substitute in each context.
256 Returns a form where all lambdas don't have any free variables."
257 ;; What's the difference between fvrs and envs?
258 ;; Suppose that we have the code
259 ;; (lambda (..) fvr (let ((fvr 1)) (+ fvr 1)))
260 ;; only the first occurrence of fvr should be replaced by
262 ;; So initially envs and fvrs are the same thing, but when we descend to
263 ;; the 'let, we delete fvr from fvrs. Why we don't delete fvr from envs?
264 ;; Because in envs the order of variables is important. We use this list
265 ;; to find the number of a specific variable in the environment vector,
266 ;; so we never touch it(unless we enter to the other closure).
267 ;;(if (listp form) (print (car form)) form)
269 (`(,(and letsym
(or `let
* `let
)) ,binders .
,body-forms
)
271 ; let and let* special forms
272 (let ((body-forms-new '())
274 ;; next for variables needed for delayed push
275 ;; because we should process <value(s)>
276 ;; before we change any arguments
277 (lmenvs-new '()) ;needed only in case of let
278 (emvrs-new '()) ;needed only in case of let
279 (emvr-push) ;needed only in case of let*
280 (lmenv-push)) ;needed only in case of let*
282 (dolist (binder binders
)
284 (var (if (not (consp binder
))
285 (prog1 binder
(setq binder
(list binder
)))
286 (setq value
(cadr binder
))
290 ;; Check if var is a candidate for lambda lifting.
291 ((member (cons binder form
) cconv-lambda-candidates
)
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* ((fv (cdr (car cconv-freevars-alist
)))
298 (funargs (cadr (cadr value
)))
299 (funcvars (append fv funargs
))
300 (funcbodies (cddadr value
)) ; function bodies
301 (funcbodies-new '()))
302 ; lambda lifting condition
303 (if (or (not fv
) (< cconv-liftwhen
(length funcvars
)))
306 ;; (byte-compile-log-warning
307 ;; (format "Not λ-lifting `%S': %d > %d"
308 ;; var (length funcvars) cconv-liftwhen))
310 (cconv-closure-convert-rec
311 value emvrs fvrs envs lmenvs
))
314 ;; (byte-compile-log-warning
315 ;; (format "λ-lifting `%S'" var))
316 (setq cconv-freevars-alist
317 ;; Now that we know we'll λ-lift, consume the
319 (cdr cconv-freevars-alist
))
320 (dolist (elm2 funcbodies
)
321 (push ; convert function bodies
322 (cconv-closure-convert-rec
323 elm2 emvrs nil envs lmenvs
)
325 (if (eq letsym
'let
*)
326 (setq lmenv-push
(cons var fv
))
327 (push (cons var fv
) lmenvs-new
))
328 ; push lifted function
332 ,(reverse funcbodies-new
))))))))
334 ;; Check if it needs to be turned into a "ref-cell".
335 ((member (cons binder form
) cconv-captured
+mutated
)
336 ;; Declared variable is mutated and captured.
338 `(list ,(cconv-closure-convert-rec
341 (if (eq letsym
'let
*)
343 (push var emvrs-new
))))
345 ;; Normal default case.
347 (cconv-closure-convert-rec
348 value emvrs fvrs envs lmenvs
)))))
350 ;; this piece of code below letbinds free
351 ;; variables of a lambda lifted function
352 ;; if they are redefined in this let
354 ;; (let* ((fun (lambda (x) (+ x y))) (y 1)) (funcall fun 1))
355 ;; Here we can not pass y as parameter because it is
356 ;; redefined. We add a (closed-y y) declaration.
357 ;; We do that even if the function is not used inside
358 ;; this let(*). The reason why we ignore this case is
359 ;; that we can't "look forward" to see if the function
360 ;; is called there or not. To treat well this case we
361 ;; need to traverse the tree one more time to collect this
362 ;; data, and I think that it's not worth it.
364 (when (eq letsym
'let
*)
365 (let ((closedsym '())
368 (dolist (lmenv lmenvs
)
369 (when (memq var
(cdr lmenv
))
372 (concat "closed-" (symbol-name var
))))
373 (setq new-lmenv
(list (car lmenv
)))
374 (dolist (frv (cdr lmenv
)) (if (eq frv var
)
375 (push closedsym new-lmenv
)
376 (push frv new-lmenv
)))
377 (setq new-lmenv
(reverse new-lmenv
))
378 (setq old-lmenv lmenv
)))
380 (setq lmenvs
(remq old-lmenv lmenvs
))
381 (push new-lmenv lmenvs
)
382 (push `(,closedsym
,var
) binders-new
))))
383 ;; We push the element after redefined free variables are
384 ;; processed. This is important to avoid the bug when free
385 ;; variable and the function have the same name.
386 (push (list var new-val
) binders-new
)
388 (when (eq letsym
'let
*) ; update fvrs
389 (setq fvrs
(remq var fvrs
))
390 (setq emvrs
(remq var emvrs
)) ; remove if redefined
392 (push emvr-push emvrs
)
393 (setq emvr-push nil
))
394 (setq lmenvs
(cconv--map-diff-elem lmenvs var
))
396 (push lmenv-push lmenvs
)
397 (setq lmenv-push nil
)))
398 )) ; end of dolist over binders
399 (when (eq letsym
'let
)
401 ;; Here we update emvrs, fvrs and lmenvs lists
402 (setq fvrs
(cconv--set-diff-map fvrs binders-new
))
403 (setq emvrs
(cconv--set-diff-map emvrs binders-new
))
404 (setq emvrs
(append emvrs emvrs-new
))
405 (setq lmenvs
(cconv--set-diff-map lmenvs binders-new
))
406 (setq lmenvs
(append lmenvs lmenvs-new
))
408 ;; Here we do the same letbinding as for let* above
409 ;; to avoid situation when a free variable of a lambda lifted
410 ;; function got redefined.
416 (dolist (binder binders
)
417 (setq var
(if (consp binder
) (car binder
) binder
))
419 (let ((lmenvs-1 lmenvs
)) ; just to avoid manipulating
420 (dolist (lmenv lmenvs-1
) ; the counter inside the loop
421 (when (memq var
(cdr lmenv
))
422 (setq closedsym
(make-symbol
426 (setq new-lmenv
(list (car lmenv
)))
427 (dolist (frv (cdr lmenv
))
428 (push (if (eq frv var
) closedsym frv
)
430 (setq new-lmenv
(reverse new-lmenv
))
431 (setq lmenvs
(remq lmenv lmenvs
))
432 (push new-lmenv lmenvs
)
433 (push `(,closedsym
,var
) letbinds
)
435 (setq binders-new
(append binders-new letbinds
))))
437 (dolist (elm body-forms
) ; convert body forms
438 (push (cconv-closure-convert-rec
439 elm emvrs fvrs envs lmenvs
)
441 `(,letsym
,(reverse binders-new
) .
,(reverse body-forms-new
))))
442 ;end of let let* forms
444 ; first element is lambda expression
445 (`(,(and `(lambda .
,_
) fun
) .
,other-body-forms
)
447 (let ((other-body-forms-new '()))
448 (dolist (elm other-body-forms
)
449 (push (cconv-closure-convert-rec
450 elm emvrs fvrs envs lmenvs
)
451 other-body-forms-new
))
453 ,(cconv-closure-convert-rec
454 (list 'function fun
) emvrs fvrs envs lmenvs
)
455 ,@(nreverse other-body-forms-new
))))
457 (`(cond .
,cond-forms
) ; cond special form
458 (let ((cond-forms-new '()))
459 (dolist (elm cond-forms
)
460 (push (let ((elm-new '()))
463 (cconv-closure-convert-rec
464 elm-2 emvrs fvrs envs lmenvs
)
469 (reverse cond-forms-new
))))
473 (`(function (lambda ,vars .
,body-forms
)) ; function form
474 (cconv-closure-convert-function
475 fvrs vars emvrs envs lmenvs body-forms form
))
477 (`(internal-make-closure .
,_
)
478 (error "Internal byte-compiler error: cconv called twice"))
480 (`(function .
,_
) form
) ; Same as quote.
483 (`(,(and sym
(or `defconst
`defvar
)) ,definedsymbol .
,body-forms
)
485 (let ((body-forms-new '()))
486 (dolist (elm body-forms
)
487 (push (cconv-closure-convert-rec
488 elm emvrs fvrs envs lmenvs
)
490 (setq body-forms-new
(reverse body-forms-new
))
491 `(,sym
,definedsymbol .
,body-forms-new
)))
494 (`(,(and sym
(or `defun
`defmacro
))
495 ,func
,vars .
,body-forms
)
497 ;; The freevar data was pushed onto cconv-freevars-alist
498 ;; but we don't need it.
499 (assert (equal body-forms
(caar cconv-freevars-alist
)))
500 (assert (null (cdar cconv-freevars-alist
)))
501 (setq cconv-freevars-alist
(cdr cconv-freevars-alist
))
503 (let ((body-new '()) ; The whole body.
504 (body-forms-new '()) ; Body w\o docstring and interactive.
506 ; Find mutable arguments.
508 (when (member (cons (list elm
) form
) cconv-captured
+mutated
)
511 ;Transform body-forms.
512 (when (stringp (car body-forms
)) ; Treat docstring well.
513 (push (car body-forms
) body-new
)
514 (setq body-forms
(cdr body-forms
)))
515 (when (eq (car-safe (car body-forms
)) 'interactive
)
516 (push (cconv-closure-convert-rec
518 emvrs fvrs envs lmenvs
)
520 (setq body-forms
(cdr body-forms
)))
522 (dolist (elm body-forms
)
523 (push (cconv-closure-convert-rec
524 elm emvrs fvrs envs lmenvs
)
526 (setq body-forms-new
(reverse body-forms-new
))
529 ; Letbind mutable arguments.
530 (let ((binders-new '()))
531 (dolist (elm letbind
) (push `(,elm
(list ,elm
))
533 (push `(let ,(reverse binders-new
) .
534 ,body-forms-new
) body-new
)
535 (setq body-new
(reverse body-new
)))
536 (setq body-new
(append (reverse body-new
) body-forms-new
)))
538 `(,sym
,func
,vars .
,body-new
)))
541 (`(condition-case ,var
,protected-form .
,handlers
)
542 (let ((newform (cconv-closure-convert-rec
543 `(function (lambda () ,protected-form
))
544 emvrs fvrs envs lmenvs
)))
545 (setq fvrs
(remq var fvrs
))
546 `(condition-case :fun-body
,newform
547 ,@(mapcar (lambda (handler)
549 (cconv-closure-convert-rec
550 (let ((arg (or var cconv--dummy-var
)))
551 `(function (lambda (,arg
) ,@(cdr handler
))))
552 emvrs fvrs envs lmenvs
)))
555 (`(,(and head
(or `catch
`unwind-protect
)) ,form .
,body
)
556 `(,head
,(cconv-closure-convert-rec form emvrs fvrs envs lmenvs
)
558 ,(cconv-closure-convert-rec `(function (lambda () ,@body
))
559 emvrs fvrs envs lmenvs
)))
561 (`(track-mouse .
,body
)
564 ,(cconv-closure-convert-rec `(function (lambda () ,@body
))
565 emvrs fvrs envs lmenvs
)))
567 (`(setq .
,forms
) ; setq special form
568 (let (prognlist sym sym-new value
)
570 (setq sym
(car forms
))
571 (setq sym-new
(cconv-closure-convert-rec
573 (remq sym emvrs
) fvrs envs lmenvs
))
575 (cconv-closure-convert-rec
576 (cadr forms
) emvrs fvrs envs lmenvs
))
578 ((memq sym emvrs
) (push `(setcar ,sym-new
,value
) prognlist
))
579 ((symbolp sym-new
) (push `(setq ,sym-new
,value
) prognlist
))
580 ;; This should never happen, but for variables which are
581 ;; mutated+captured+unused, we may end up trying to `setq'
582 ;; on a closed-over variable, so just drop the setq.
583 (t (push value prognlist
)))
584 (setq forms
(cddr forms
)))
586 `(progn .
,(reverse prognlist
))
589 (`(,(and (or `funcall
`apply
) callsym
) ,fun .
,args
)
590 ; funcall is not a special form
591 ; but we treat it separately
592 ; for the needs of lambda lifting
593 (let ((fv (cdr (assq fun lmenvs
))))
597 ;; All args (free variables and actual arguments)
598 ;; should be processed, because they can be fvrs
599 ;; (free variables of another closure)
601 (push (cconv-closure-convert-rec
605 (setq processed-fv
(reverse processed-fv
))
607 (push (cconv-closure-convert-rec
608 elm emvrs fvrs envs lmenvs
)
610 (setq args-new
(append processed-fv
(reverse args-new
)))
611 (setq fun
(cconv-closure-convert-rec
612 fun emvrs fvrs envs lmenvs
))
613 `(,callsym
,fun .
,args-new
))
615 (dolist (elm (cdr form
))
616 (push (cconv-closure-convert-rec
617 elm emvrs fvrs envs lmenvs
)
619 `(,callsym .
,(reverse cdr-new
))))))
621 (`(interactive .
,forms
)
623 ,@(mapcar (lambda (form)
624 (cconv-closure-convert-rec form nil nil nil nil
))
627 (`(,func .
,body-forms
) ; first element is function or whatever
628 ; function-like forms are:
629 ; or, and, if, progn, prog1, prog2,
631 (let ((body-forms-new '()))
632 (dolist (elm body-forms
)
633 (push (cconv-closure-convert-rec
634 elm emvrs fvrs envs lmenvs
)
636 (setq body-forms-new
(reverse body-forms-new
))
637 `(,func .
,body-forms-new
)))
640 (let ((free (memq form fvrs
)))
641 (if free
;form is a free variable
642 (let* ((numero (- (length fvrs
) (length free
)))
643 ;; Replace form => (aref env #)
644 (var `(internal-get-closed-var ,numero
)))
645 (if (memq form emvrs
) ; form => (car (aref env #)) if mutable
648 (if (memq form emvrs
) ; if form is a mutable variable
649 `(car ,form
) ; replace form => (car form)
652 (unless (fboundp 'byte-compile-not-lexical-var-p
)
653 ;; Only used to test the code in non-lexbind Emacs.
654 (defalias 'byte-compile-not-lexical-var-p
'boundp
))
656 (defun cconv-analyse-use (vardata form varkind
)
657 "Analyse the use of a variable.
658 VARDATA should be (BINDER READ MUTATED CAPTURED CALLED).
659 VARKIND is the name of the kind of variable.
660 FORM is the parent form that binds this var."
661 ;; use = `(,binder ,read ,mutated ,captured ,called)
663 (`(,_ nil nil nil nil
) nil
)
664 (`((,(and (pred (lambda (var) (eq ?_
(aref (symbol-name var
) 0)))) var
) .
,_
)
666 (byte-compile-log-warning (format "%s `%S' not left unused" varkind var
)))
667 ((or `(,_
,_
,_
,_
,_
) dontcare
) nil
))
669 (`((,var .
,_
) nil
,_
,_ nil
)
670 ;; FIXME: This gives warnings in the wrong order, with imprecise line
671 ;; numbers and without function name info.
672 (unless (or ;; Uninterned symbols typically come from macro-expansion, so
673 ;; it is often non-trivial for the programmer to avoid such
675 (not (intern-soft var
))
676 (eq ?_
(aref (symbol-name var
) 0)))
677 (byte-compile-log-warning (format "Unused lexical %s `%S'"
679 ;; If it's unused, there's no point converting it into a cons-cell, even if
680 ;; it's captured and mutated.
681 (`(,binder
,_ t t
,_
)
682 (push (cons binder form
) cconv-captured
+mutated
))
683 (`(,(and binder
`(,_
(function (lambda .
,_
)))) nil nil nil t
)
684 (push (cons binder form
) cconv-lambda-candidates
))
685 (`(,_
,_
,_
,_
,_
) nil
)
688 (defun cconv-analyse-function (args body env parentform
)
690 (freevars (list body
))
691 ;; We analyze the body within a new environment where all uses are
692 ;; nil, so we can distinguish uses within that function from uses
695 (mapcar (lambda (vdata) (list (car vdata
) nil nil nil nil
)) env
))
697 ;; Push it before recursing, so cconv-freevars-alist contains entries in
698 ;; the order they'll be used by closure-convert-rec.
699 (push freevars cconv-freevars-alist
)
702 ((byte-compile-not-lexical-var-p arg
)
703 (byte-compile-report-error
704 (format "Argument %S is not a lexical variable" arg
)))
705 ((eq ?
& (aref (symbol-name arg
) 0)) nil
) ;Ignore &rest, &optional, ...
706 (t (let ((varstruct (list arg nil nil nil nil
)))
707 (push (cons (list arg
) (cdr varstruct
)) newvars
)
708 (push varstruct newenv
)))))
709 (dolist (form body
) ;Analyse body forms.
710 (cconv-analyse-form form newenv
))
711 ;; Summarize resulting data about arguments.
712 (dolist (vardata newvars
)
713 (cconv-analyse-use vardata parentform
"argument"))
714 ;; Transfer uses collected in `envcopy' (via `newenv') back to `env';
715 ;; and compute free variables.
717 (assert (and envcopy
(eq (caar env
) (caar envcopy
))))
720 (y (cdr (car envcopy
))))
722 (when (car y
) (setcar x t
) (setq free t
))
723 (setq x
(cdr x
) y
(cdr y
)))
725 (push (caar env
) (cdr freevars
))
726 (setf (nth 3 (car env
)) t
))
727 (setq env
(cdr env
) envcopy
(cdr envcopy
))))))
729 (defun cconv-analyse-form (form env
)
730 "Find mutated variables and variables captured by closure.
731 Analyse lambdas if they are suitable for lambda lifting.
732 - FORM is a piece of Elisp code after macroexpansion.
733 - ENV is an alist mapping each enclosing lexical variable to its info.
734 I.e. each element has the form (VAR . (READ MUTATED CAPTURED CALLED)).
735 This function does not return anything but instead fills the
736 `cconv-captured+mutated' and `cconv-lambda-candidates' variables
737 and updates the data stored in ENV."
740 (`(,(and (or `let
* `let
) letsym
) ,binders .
,body-forms
)
746 (dolist (binder binders
)
747 (if (not (consp binder
))
749 (setq var binder
) ; treat the form (let (x) ...) well
750 (setq binder
(list binder
))
752 (setq var
(car binder
))
753 (setq value
(cadr binder
))
755 (cconv-analyse-form value
(if (eq letsym
'let
*) env orig-env
)))
757 (unless (byte-compile-not-lexical-var-p var
)
758 (let ((varstruct (list var nil nil nil nil
)))
759 (push (cons binder
(cdr varstruct
)) newvars
)
760 (push varstruct env
))))
762 (dolist (form body-forms
) ; Analyse body forms.
763 (cconv-analyse-form form env
))
765 (dolist (vardata newvars
)
766 (cconv-analyse-use vardata form
"variable"))))
769 (`(,(or `defun
`defmacro
) ,func
,vrs .
,body-forms
)
771 (byte-compile-log-warning
772 (format "Function %S will ignore its context %S"
773 func
(mapcar #'car env
))
775 (cconv-analyse-function vrs body-forms nil form
))
777 (`(function (lambda ,vrs .
,body-forms
))
778 (cconv-analyse-function vrs body-forms env form
))
781 ;; If a local variable (member of env) is modified by setq then
782 ;; it is a mutated variable.
784 (let ((v (assq (car forms
) env
))) ; v = non nil if visible
785 (when v
(setf (nth 2 v
) t
)))
786 (cconv-analyse-form (cadr forms
) env
)
787 (setq forms
(cddr forms
))))
789 (`((lambda .
,_
) .
,_
) ; first element is lambda expression
790 (dolist (exp `((function ,(car form
)) .
,(cdr form
)))
791 (cconv-analyse-form exp env
)))
793 (`(cond .
,cond-forms
) ; cond special form
794 (dolist (forms cond-forms
)
795 (dolist (form forms
) (cconv-analyse-form form env
))))
797 (`(quote .
,_
) nil
) ; quote form
798 (`(function .
,_
) nil
) ; same as quote
800 (`(condition-case ,var
,protected-form .
,handlers
)
801 ;; FIXME: The bytecode for condition-case forces us to wrap the
802 ;; form and handlers in closures (for handlers, it's probably
803 ;; unavoidable, but not for the protected form).
804 (cconv-analyse-function () (list protected-form
) env form
)
805 (dolist (handler handlers
)
806 (cconv-analyse-function (if var
(list var
)) (cdr handler
) env form
)))
808 ;; FIXME: The bytecode for catch forces us to wrap the body.
809 (`(,(or `catch
`unwind-protect
) ,form .
,body
)
810 (cconv-analyse-form form env
)
811 (cconv-analyse-function () body env form
))
813 ;; FIXME: The bytecode for save-window-excursion and the lack of
814 ;; bytecode for track-mouse forces us to wrap the body.
815 (`(track-mouse .
,body
)
816 (cconv-analyse-function () body env form
))
818 (`(,(or `defconst
`defvar
) ,var
,value .
,_
)
819 (push var byte-compile-bound-variables
)
820 (cconv-analyse-form value env
))
822 (`(,(or `funcall
`apply
) ,fun .
,args
)
823 ;; Here we ignore fun because funcall and apply are the only two
824 ;; functions where we can pass a candidate for lambda lifting as
825 ;; argument. So, if we see fun elsewhere, we'll delete it from
826 ;; lambda candidate list.
827 (let ((fdata (and (symbolp fun
) (assq fun env
))))
829 (setf (nth 4 fdata
) t
)
830 (cconv-analyse-form fun env
)))
831 (dolist (form args
) (cconv-analyse-form form env
)))
833 (`(interactive .
,forms
)
834 ;; These appear within the function body but they don't have access
835 ;; to the function's arguments.
836 ;; We could extend this to allow interactive specs to refer to
837 ;; variables in the function's enclosing environment, but it doesn't
838 ;; seem worth the trouble.
839 (dolist (form forms
) (cconv-analyse-form form nil
)))
841 (`(,_ .
,body-forms
) ; First element is a function or whatever.
842 (dolist (form body-forms
) (cconv-analyse-form form env
)))
845 (let ((dv (assq form env
))) ; dv = declared and visible
847 (setf (nth 1 dv
) t
))))))
850 ;;; cconv.el ends here