| blob | 04bb8d6b185d5a519f4b64149071b8bdd64599db |
1 ;;; byte-opt.el --- the optimization passes of the emacs-lisp byte compiler
3 ;; Copyright (C) 1991, 1994, 2000, 2001, 2002, 2003, 2004,
4 ;; 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
6 ;; Author: Jamie Zawinski <jwz@lucid.com>
7 ;; Hallvard Furuseth <hbf@ulrik.uio.no>
8 ;; Maintainer: FSF
9 ;; Keywords: internal
11 ;; This file is part of GNU Emacs.
13 ;; GNU Emacs is free software; you can redistribute it and/or modify
14 ;; it under the terms of the GNU General Public License as published by
15 ;; the Free Software Foundation; either version 3, or (at your option)
16 ;; any later version.
18 ;; GNU Emacs is distributed in the hope that it will be useful,
19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 ;; GNU General Public License for more details.
23 ;; You should have received a copy of the GNU General Public License
24 ;; along with GNU Emacs; see the file COPYING. If not, write to the
25 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
26 ;; Boston, MA 02110-1301, USA.
28 ;;; Commentary:
30 ;; ========================================================================
31 ;; "No matter how hard you try, you can't make a racehorse out of a pig.
32 ;; You can, however, make a faster pig."
33 ;;
34 ;; Or, to put it another way, the Emacs byte compiler is a VW Bug. This code
35 ;; makes it be a VW Bug with fuel injection and a turbocharger... You're
36 ;; still not going to make it go faster than 70 mph, but it might be easier
37 ;; to get it there.
38 ;;
40 ;; TO DO:
41 ;;
42 ;; (apply (lambda (x &rest y) ...) 1 (foo))
43 ;;
44 ;; maintain a list of functions known not to access any global variables
45 ;; (actually, give them a 'dynamically-safe property) and then
46 ;; (let ( v1 v2 ... vM vN ) <...dynamically-safe...> ) ==>
47 ;; (let ( v1 v2 ... vM ) vN <...dynamically-safe...> )
48 ;; by recursing on this, we might be able to eliminate the entire let.
49 ;; However certain variables should never have their bindings optimized
50 ;; away, because they affect everything.
51 ;; (put 'debug-on-error 'binding-is-magic t)
52 ;; (put 'debug-on-abort 'binding-is-magic t)
53 ;; (put 'debug-on-next-call 'binding-is-magic t)
54 ;; (put 'inhibit-quit 'binding-is-magic t)
55 ;; (put 'quit-flag 'binding-is-magic t)
56 ;; (put 't 'binding-is-magic t)
57 ;; (put 'nil 'binding-is-magic t)
58 ;; possibly also
59 ;; (put 'gc-cons-threshold 'binding-is-magic t)
60 ;; (put 'track-mouse 'binding-is-magic t)
61 ;; others?
62 ;;
63 ;; Simple defsubsts often produce forms like
64 ;; (let ((v1 (f1)) (v2 (f2)) ...)
65 ;; (FN v1 v2 ...))
66 ;; It would be nice if we could optimize this to
67 ;; (FN (f1) (f2) ...)
68 ;; but we can't unless FN is dynamically-safe (it might be dynamically
69 ;; referring to the bindings that the lambda arglist established.)
70 ;; One of the uncountable lossages introduced by dynamic scope...
71 ;;
72 ;; Maybe there should be a control-structure that says "turn on
73 ;; fast-and-loose type-assumptive optimizations here." Then when
74 ;; we see a form like (car foo) we can from then on assume that
75 ;; the variable foo is of type cons, and optimize based on that.
76 ;; But, this won't win much because of (you guessed it) dynamic
77 ;; scope. Anything down the stack could change the value.
78 ;; (Another reason it doesn't work is that it is perfectly valid
79 ;; to call car with a null argument.) A better approach might
80 ;; be to allow type-specification of the form
81 ;; (put 'foo 'arg-types '(float (list integer) dynamic))
82 ;; (put 'foo 'result-type 'bool)
83 ;; It should be possible to have these types checked to a certain
84 ;; degree.
85 ;;
86 ;; collapse common subexpressions
87 ;;
88 ;; It would be nice if redundant sequences could be factored out as well,
89 ;; when they are known to have no side-effects:
90 ;; (list (+ a b c) (+ a b c)) --> a b add c add dup list-2
91 ;; but beware of traps like
92 ;; (cons (list x y) (list x y))
93 ;;
94 ;; Tail-recursion elimination is not really possible in Emacs Lisp.
95 ;; Tail-recursion elimination is almost always impossible when all variables
96 ;; have dynamic scope, but given that the "return" byteop requires the
97 ;; binding stack to be empty (rather than emptying it itself), there can be
98 ;; no truly tail-recursive Emacs Lisp functions that take any arguments or
99 ;; make any bindings.
100 ;;
101 ;; Here is an example of an Emacs Lisp function which could safely be
102 ;; byte-compiled tail-recursively:
103 ;;
104 ;; (defun tail-map (fn list)
105 ;; (cond (list
106 ;; (funcall fn (car list))
107 ;; (tail-map fn (cdr list)))))
108 ;;
109 ;; However, if there was even a single let-binding around the COND,
110 ;; it could not be byte-compiled, because there would be an "unbind"
111 ;; byte-op between the final "call" and "return." Adding a
112 ;; Bunbind_all byteop would fix this.
113 ;;
114 ;; (defun foo (x y z) ... (foo a b c))
115 ;; ... (const foo) (varref a) (varref b) (varref c) (call 3) END: (return)
116 ;; ... (varref a) (varbind x) (varref b) (varbind y) (varref c) (varbind z) (goto 0) END: (unbind-all) (return)
117 ;; ... (varref a) (varset x) (varref b) (varset y) (varref c) (varset z) (goto 0) END: (return)
118 ;;
119 ;; this also can be considered tail recursion:
120 ;;
121 ;; ... (const foo) (varref a) (call 1) (goto X) ... X: (return)
122 ;; could generalize this by doing the optimization
123 ;; (goto X) ... X: (return) --> (return)
124 ;;
125 ;; But this doesn't solve all of the problems: although by doing tail-
126 ;; recursion elimination in this way, the call-stack does not grow, the
127 ;; binding-stack would grow with each recursive step, and would eventually
128 ;; overflow. I don't believe there is any way around this without lexical
129 ;; scope.
130 ;;
131 ;; Wouldn't it be nice if Emacs Lisp had lexical scope.
132 ;;
133 ;; Idea: the form (lexical-scope) in a file means that the file may be
134 ;; compiled lexically. This proclamation is file-local. Then, within
135 ;; that file, "let" would establish lexical bindings, and "let-dynamic"
136 ;; would do things the old way. (Or we could use CL "declare" forms.)
137 ;; We'd have to notice defvars and defconsts, since those variables should
138 ;; always be dynamic, and attempting to do a lexical binding of them
139 ;; should simply do a dynamic binding instead.
140 ;; But! We need to know about variables that were not necessarily defvarred
141 ;; in the file being compiled (doing a boundp check isn't good enough.)
142 ;; Fdefvar() would have to be modified to add something to the plist.
143 ;;
144 ;; A major disadvantage of this scheme is that the interpreter and compiler
145 ;; would have different semantics for files compiled with (dynamic-scope).
146 ;; Since this would be a file-local optimization, there would be no way to
147 ;; modify the interpreter to obey this (unless the loader was hacked
148 ;; in some grody way, but that's a really bad idea.)
150 ;; Other things to consider:
152 ;; ;; Associative math should recognize subcalls to identical function:
153 ;; (disassemble (lambda (x) (+ (+ (foo) 1) (+ (bar) 2))))
154 ;; ;; This should generate the same as (1+ x) and (1- x)
156 ;; (disassemble (lambda (x) (cons (+ x 1) (- x 1))))
157 ;; ;; An awful lot of functions always return a non-nil value. If they're
158 ;; ;; error free also they may act as true-constants.
160 ;; (disassemble (lambda (x) (and (point) (foo))))
161 ;; ;; When
162 ;; ;; - all but one arguments to a function are constant
163 ;; ;; - the non-constant argument is an if-expression (cond-expression?)
164 ;; ;; then the outer function can be distributed. If the guarding
165 ;; ;; condition is side-effect-free [assignment-free] then the other
166 ;; ;; arguments may be any expressions. Since, however, the code size
167 ;; ;; can increase this way they should be "simple". Compare:
169 ;; (disassemble (lambda (x) (eq (if (point) 'a 'b) 'c)))
170 ;; (disassemble (lambda (x) (if (point) (eq 'a 'c) (eq 'b 'c))))
172 ;; ;; (car (cons A B)) -> (prog1 A B)
173 ;; (disassemble (lambda (x) (car (cons (foo) 42))))
175 ;; ;; (cdr (cons A B)) -> (progn A B)
176 ;; (disassemble (lambda (x) (cdr (cons 42 (foo)))))
178 ;; ;; (car (list A B ...)) -> (prog1 A B ...)
179 ;; (disassemble (lambda (x) (car (list (foo) 42 (bar)))))
181 ;; ;; (cdr (list A B ...)) -> (progn A (list B ...))
182 ;; (disassemble (lambda (x) (cdr (list 42 (foo) (bar)))))
185 ;;; Code:
201 arg)
217 c
219 args)))))
225 \f
226 ;;; byte-compile optimizers to support inlining
231 "byte-optimize-handler for the `inline' special-form."
244 sexp)))
248 ;; Splice the given lap code into the current instruction stream.
249 ;; If it has any labels in it, you're responsible for making sure there
250 ;; are no collisions, and that byte-compile-tag-number is reasonable
251 ;; after this is spliced in. The provided list is destroyed.
262 name)
263 form)
264 ;; else
277 ;; Isn't it an error for `string' not to be unibyte?? --stef
280 ;; `byte-compile-splice-in-already-compiled-code'
281 ;; takes care of inlining the body.
287 ;; Give up on inlining.
288 form))))))
290 ;; ((lambda ...) ...)
301 optionalp restp
302 bindings)
309 ;; ok, I'll let this slide because funcall_lambda() does...
310 ;; (if optionalp (error "multiple &optional keywords in %s" name))
316 ;; ...but it is by no stretch of the imagination a reasonable
317 ;; thing that funcall_lambda() allows (&rest x y) and
318 ;; (&rest x &optional y) in arglists.
327 bindings)
328 values nil))
334 bindings)
342 form)
344 ;; The following leads to infinite recursion when loading a
345 ;; file containing `(defsubst f () (f))', and then trying to
346 ;; byte-compile that file.
347 ;(setq body (mapcar 'byte-optimize-form body)))
354 newform)))))
356 \f
357 ;;; implementing source-level optimizers
360 ;;
361 ;; For normal function calls, We can just mapcar the optimizer the cdr. But
362 ;; we need to have special knowledge of the syntax of the special forms
363 ;; like let and defun (that's why they're special forms :-). (Actually,
364 ;; the important aspect is that they are subrs that don't evaluate all of
365 ;; their args.)
366 ;;
368 tmp)
374 form))
379 ;; map (quote nil) to nil to simplify optimizer logic.
380 ;; map quoted constants to nil if for-effect (just because).
383 form))
388 for-effect))
390 ;; recursively enter the optimizer for the bindings and body
391 ;; of a let or let*. This for depth-firstness: forms that
392 ;; are more deeply nested are optimized first.
397 binding
414 clause))
417 ;; as an extra added bonus, this simplifies (progn <x>) --> <x>
436 ;; those subrs which have an implicit progn; it's not quite good
437 ;; enough to treat these like normal function calls.
438 ;; This can turn (save-excursion ...) into (save-excursion) which
439 ;; will be optimized away in the lap-optimize pass.
443 ;; this is just like the above, except for the first argument.
459 ;; take forms off the back until we can't any more.
460 ;; In the future it could conceivably be a problem that the
461 ;; subexpressions of these forms are optimized in the reverse
462 ;; order, but it's ok for now.
468 for-effect))))
480 nil)
483 condition-case save-window-excursion))
484 ;; These forms are compiled as constants or by breaking out
485 ;; all the subexpressions and compiling them separately.
486 form)
489 ;; the "protected" part of an unwind-protect is compiled (and thus
490 ;; optimized) as a top-level form, so don't do it here. But the
491 ;; non-protected part has the same for-effect status as the
492 ;; unwind-protect itself. (The protected part is always for effect,
493 ;; but that isn't handled properly yet.)
499 ;; the body of a catch is compiled (and thus optimized) as a
500 ;; top-level form, so don't do it here. The tag is never
501 ;; for-effect. The body should have the same for-effect status
502 ;; as the catch form itself, but that isn't handled properly yet.
508 ;; Don't treat the args to `ignore' as being
509 ;; computed for effect. We want to avoid the warnings
510 ;; that might occur if they were treated that way.
511 ;; However, don't actually bother calling `ignore'.
514 ;; If optimization is on, this is the only place that macros are
515 ;; expanded. If optimization is off, then macroexpansion happens
516 ;; in byte-compile-form. Otherwise, the macros are already expanded
517 ;; by the time that is reached.
520 byte-compile-macro-environment))))
523 ;; Support compiler macros as in cl.el.
535 form)
540 ;; Detect the expansion of (pop foo).
541 ;; There is no need to compile the call to `car' there.
555 nil)))
557 ;; appending a nil here might not be necessary, but it can't hurt.
562 ;; Otherwise, no args can be considered to be for-effect,
563 ;; even if the called function is for-effect, because we
564 ;; don't know anything about that function.
572 "Non-nil if all elements of LIST satisfy `byte-compile-constp'."
578 constant))
581 "The source-level pass of the optimizer."
582 ;;
583 ;; First, optimize all sub-forms of this one.
585 ;;
586 ;; after optimizing all subforms, optimize this form until it doesn't
587 ;; optimize any further. This means that some forms will be passed through
588 ;; the optimizer many times, but that's necessary to make the for-effect
589 ;; processing do as much as possible.
590 ;;
595 ;; we don't have any of these yet, but we might.
600 ;; (if (equal form new) (error "bogus optimizer -- %s" opt))
603 new)
604 form)))
608 ;; optimize the cdr of a progn or implicit progn; all forms is a list of
609 ;; forms, all but the last of which are optimized with the assumption that
610 ;; they are being called for effect. the last is for-effect as well if
611 ;; all-for-effect is true. returns a new list of forms.
614 fe new)
623 \f
624 ;; some source-level optimizers
625 ;;
626 ;; when writing optimizers, be VERY careful that the optimizer returns
627 ;; something not EQ to its argument if and ONLY if it has made a change.
628 ;; This implies that you cannot simply destructively modify the list;
629 ;; you must return something not EQ to it if you make an optimization.
630 ;;
631 ;; It is now safe to optimize code such that it introduces new bindings.
634 "Return non-nil if FORM always evaluates to a non-nil value."
640 ;; Can't use recursion in a defsubst.
641 ;; (progn (byte-compile-trueconstp (car (last (cdr form)))))
642 ))
648 "Return non-nil if FORM always evaluates to a nil value."
654 ;; Can't use recursion in a defsubst.
655 ;; (progn (byte-compile-nilconstp (car (last (cdr form)))))
656 ))
660 ;; If the function is being called with constant numeric args,
661 ;; evaluate as much as possible at compile-time. This optimizer
662 ;; assumes that the function is associative, like + or *.
680 form)))
682 ;; If the function is being called with constant numeric args,
683 ;; evaluate as much as possible at compile-time. This optimizer
684 ;; assumes that the function satisfies
685 ;; (op x1 x2 ... xn) == (op ...(op (op x1 x2) x3) ...xn)
686 ;; like - and /.
690 form
698 constant))))
700 ;;(defun byte-optimize-associative-two-args-math (form)
701 ;; (setq form (byte-optimize-associative-math form))
702 ;; (if (consp form)
703 ;; (byte-optimize-two-args-left form)
704 ;; form))
706 ;;(defun byte-optimize-nonassociative-two-args-math (form)
707 ;; (setq form (byte-optimize-nonassociative-math form))
708 ;; (if (consp form)
709 ;; (byte-optimize-two-args-right form)
710 ;; form))
715 ;; Collect all the constants from FORM, after the STARTth arg,
716 ;; and apply FUN to them to make one argument at the end.
717 ;; For functions that can handle floats, that optimization
718 ;; can be incorrect because reordering can cause an overflow
719 ;; that would otherwise be avoided by encountering an arg that is a float.
720 ;; We avoid this problem by (1) not moving float constants and
721 ;; (2) not moving anything if it would cause an overflow.
723 ;; Merge all FORM's constants from number START, call FUN on them
724 ;; and put the result at the end.
727 ;; t means we must check for overflow.
738 ;; If necessary, check now for overflow
739 ;; that might be caused by reordering.
741 ;; We have overflow if the result of doing the arithmetic
742 ;; on floats is not even close to the result
743 ;; of doing it on integers.
750 form))
755 ;;(setq form (byte-optimize-associative-two-args-math form))
760 ;;; It is not safe to delete the function entirely
761 ;;; (actually, it would be safe if we know the sole arg
762 ;;; is not a marker).
763 ;;; ((null (cdr (cdr form))) (nth 1 form))
767 form))
771 ;; Optimize (+ x 1) into (1+ x) and (+ x -1) into (1- x).
781 other)))
785 ;; Put constants at the end, except the last constant.
787 ;; Now only first and last element can be a number.
790 ;; (- x y ... 0) --> (- x y ...)
797 ;; If form is (- CONST foo... CONST), merge first and last.
802 ;;; It is not safe to delete the function entirely
803 ;;; (actually, it would be safe if we know the sole arg
804 ;;; is not a marker).
805 ;;; (if (eq (nth 2 form) 0)
806 ;;; (nth 1 form) ; (- x 0) --> x
811 form))
812 ;;; )
813 )
817 ;; If there is a constant in FORM, it is now the last element.
819 ;;; It is not safe to delete the function entirely
820 ;;; (actually, it would be safe if we know the sole arg
821 ;;; is not a marker or if it appears in other arithmetic).
822 ;;; ((null (cdr (cdr form))) (nth 1 form))
854 last nil))))
856 ;;; ((null (cdr (cdr form)))
857 ;;; (nth 1 form))
885 ;; This can enable some lapcode optimizations.
887 form))
899 form)))
907 form))
951 ;; I'm not convinced that this is necessary. Doesn't the optimizer loop
952 ;; take care of this? - Jamie
953 ;; I think this may some times be necessary to reduce ie (quote 5) to 5,
954 ;; so arithmetic optimizers recognize the numeric constant. - Hallvard
960 form
973 ;; Simplify if less than 2 args.
974 ;; if there is a literal nil in the args to `and', throw it and following
975 ;; forms away, and surround the `and' with (progn ... nil).
984 nil))
990 ;; Throw away nil's, and simplify if less than 2 args.
991 ;; If there is a literal non-nil constant in the args to `or', throw away all
992 ;; following forms.
1005 ;; if any clauses have a literal nil as their test, throw them away.
1006 ;; if any clause has a literal non-nil constant as its test, throw
1007 ;; away all following clauses.
1009 ;; This must be first, to reduce (cond (t ...) (nil)) to (progn t ...)
1017 ;; This branch will always be taken: kill the subsequent ones.
1026 ;; This branch will never be taken: kill its body.
1028 ;;
1029 ;; Turn (cond (( <x> )) ... ) into (or <x> (cond ... ))
1037 form))
1038 form))
1041 ;; (if (progn <insts> <test>) <rest>) ==> (progn <insts> (if <test> <rest>))
1042 ;; (if <true-constant> <then> <else...>) ==> <then>
1043 ;; (if <false-constant> <then> <else...>) ==> (progn <else...>)
1044 ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>))
1045 ;; (if <test> <then> nil) ==> (if <test> <then>)
1048 ;; `clause' is a proper list.
1051 ;; A trivial `progn'.
1064 form))
1067 ;; Don't make a double negative;
1068 ;; instead, take away the one that is there.
1083 form))
1091 ;; byte-compile-negation-optimizer lives in bytecomp.el
1098 ;; (funcall (lambda ...) ...) ==> ((lambda ...) ...)
1099 ;; (funcall foo ...) ==> (foo ...)
1103 form)))
1106 ;; If the last arg is a literal constant, turn this into a funcall.
1107 ;; The funcall optimizer can then transform (funcall 'foo ...) -> (foo ...).
1117 "last arg to apply can't be a literal atom: `%s'"
1119 nil))
1120 form)))
1130 ;; No bindings
1133 form)
1134 ;; The body is nil
1151 form))
1161 form)
1163 form))
1165 ;; Fixme: delete-char -> delete-region (byte-coded)
1166 ;; optimize string-as-unibyte, string-as-multibyte, string-make-unibyte,
1167 ;; string-make-multibyte for constant args.
1171 ;; Emacs-21's byte-code doesn't run under XEmacs or SXEmacs anyway, so we
1172 ;; can safely optimize away this test.
1174 nil
1176 t
1177 form)))
1190 \f
1191 ;; enumerating those functions which need not be called if the returned
1192 ;; value is not used. That is, something like
1193 ;; (progn (list (something-with-side-effects) (yow))
1194 ;; (foo))
1195 ;; may safely be turned into
1196 ;; (progn (progn (something-with-side-effects) (yow))
1197 ;; (foo))
1198 ;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo.
1200 ;; Some of these functions have the side effect of allocating memory
1201 ;; and it would be incorrect to replace two calls with one.
1202 ;; But we don't try to do those kinds of optimizations,
1203 ;; so it is safe to list such functions here.
1204 ;; Some of these functions return values that depend on environment
1205 ;; state, so that constant folding them would be wrong,
1206 ;; but we don't do constant folding based on this list.
1208 ;; However, at present the only optimization we normally do
1209 ;; is delete calls that need not occur, and we only do that
1210 ;; with the error-free functions.
1212 ;; I wonder if I missed any :-\)
1215 assoc assq
1216 boundp buffer-file-name buffer-local-variables buffer-modified-p
1217 buffer-substring byte-code-function-p
1218 capitalize car-less-than-car car cdr ceiling char-after char-before
1219 char-equal char-to-string char-width
1220 compare-strings concat coordinates-in-window-p
1221 copy-alist copy-sequence copy-marker cos count-lines
1222 decode-char
1223 decode-time default-boundp default-value documentation downcase
1224 elt encode-char exp expt encode-time error-message-string
1225 fboundp fceiling featurep ffloor
1226 file-directory-p file-exists-p file-locked-p file-name-absolute-p
1227 file-newer-than-file-p file-readable-p file-symlink-p file-writable-p
1228 float float-time floor format format-time-string frame-visible-p
1229 fround ftruncate
1230 get gethash get-buffer get-buffer-window getenv get-file-buffer
1231 hash-table-count
1232 int-to-string intern-soft
1233 keymap-parent
1234 length local-variable-if-set-p local-variable-p log log10 logand
1235 logb logior lognot logxor lsh langinfo
1236 make-list make-string make-symbol
1237 marker-buffer max member memq min mod multibyte-char-to-unibyte
1238 next-window nth nthcdr number-to-string
1239 parse-colon-path plist-get plist-member
1240 prefix-numeric-value previous-window prin1-to-string propertize
1241 radians-to-degrees rassq rassoc read-from-string regexp-quote
1242 region-beginning region-end reverse round
1244 string-to-int string-to-number substring sxhash symbol-function
1245 symbol-name symbol-plist symbol-value string-make-unibyte
1246 string-make-multibyte string-as-multibyte string-as-unibyte
1247 string-to-multibyte
1248 tan truncate
1249 unibyte-char-to-multibyte upcase user-full-name
1250 user-login-name user-original-login-name user-variable-p
1251 vconcat
1252 window-buffer window-dedicated-p window-edges window-height
1253 window-hscroll window-minibuffer-p window-width
1254 zerop))
1257 bobp bolp bool-vector-p
1258 buffer-end buffer-list buffer-size buffer-string bufferp
1259 car-safe case-table-p cdr-safe char-or-string-p characterp
1260 charsetp commandp cons consp
1261 current-buffer current-global-map current-indentation
1262 current-local-map current-minor-mode-maps current-time
1263 current-time-string current-time-zone
1264 eobp eolp eq equal eventp
1265 floatp following-char framep
1266 get-largest-window get-lru-window
1267 hash-table-p
1268 identity ignore integerp integer-or-marker-p interactive-p
1269 invocation-directory invocation-name
1270 keymapp
1271 line-beginning-position line-end-position list listp
1272 make-marker mark mark-marker markerp max-char
1273 memory-limit minibuffer-window
1274 mouse-movement-p
1275 natnump nlistp not null number-or-marker-p numberp
1276 one-window-p overlayp
1277 point point-marker point-min point-max preceding-char primary-charset
1278 processp
1279 recent-keys recursion-depth
1280 safe-length selected-frame selected-window sequencep
1281 standard-case-table standard-syntax-table stringp subrp symbolp
1282 syntax-table syntax-table-p
1283 this-command-keys this-command-keys-vector this-single-command-keys
1284 this-single-command-raw-keys
1285 user-real-login-name user-real-uid user-uid
1286 vector vectorp visible-frame-list
1287 wholenump window-configuration-p window-live-p windowp)))
1294 nil)
1296 \f
1297 ;; pure functions are side-effect free functions whose values depend
1298 ;; only on their arguments. For these functions, calls with constant
1299 ;; arguments can be evaluated at compile time. This may shift run time
1300 ;; errors to compile time.
1307 nil)
1310 ;; form is (byte-code "..." [...] n)
1316 byte-compile-maxdepth))
1321 \f
1325 ;; This function extracts the bitfields from variable-length opcodes.
1326 ;; Originally defined in disass.el (which no longer uses it.)
1329 "Don't call this!"
1330 ;; fetch and return the offset for the current opcode.
1331 ;; return nil if this opcode has no offset
1332 ;; OP, PTR and BYTES are used and set dynamically
1363 ;; This de-compiler is used for inline expansion of compiled functions,
1364 ;; and by the disassembler.
1365 ;;
1366 ;; This list contains numbers, which are pc values,
1367 ;; before each instruction.
1369 "Turn BYTECODE into lapcode, referring to CONSTVEC."
1375 ;; As byte-decompile-bytecode, but updates
1376 ;; byte-compile-{constants, variables, tag-number}.
1377 ;; If MAKE-SPLICEABLE is true, then `return' opcodes are replaced
1378 ;; with `goto's destined for the end of the code.
1379 ;; That is for use by the compiler.
1380 ;; If MAKE-SPLICEABLE is nil, we are being called for the disassembler.
1381 ;; In that case, we put a pc value into the list
1382 ;; before each insn (or its label).
1386 lap tmp
1387 endtag)
1392 optr ptr
1396 ;; it's a pc
1402 tags)))))))
1413 byte-compile-variables)))))))
1420 ;; lap = ( [ (pc . (op . arg)) ]* )
1422 lap))
1424 ;; take off the dummy nil op that we replaced a trailing "return" with.
1429 ;; this addr is jumped to
1440 ;; remove addrs, lap = ( [ (op . arg) | (TAG tagno) ]* )
1443 elt
1447 \f
1448 ;;; peephole optimizer
1454 byte-goto-if-not-nil-else-pop))
1458 byte-symbolp byte-consp byte-stringp byte-listp byte-numberp byte-integerp
1459 byte-eq byte-not
1460 byte-cons byte-list1 byte-list2 ; byte-list3 byte-list4
1461 byte-interactive-p)
1462 ;; How about other side-effect-free-ops? Is it safe to move an
1463 ;; error invocation (such as from nth) out of an unwind-protect?
1464 ;; No, it is not, because the unwind-protect forms can alter
1465 ;; the inside of the object to which nth would apply.
1466 ;; For the same reason, byte-equal was deleted from this list.
1471 byte-integerp byte-numberp byte-eq byte-equal byte-not byte-car-safe
1472 byte-cdr-safe byte-cons byte-list1 byte-list2 byte-point byte-point-max
1473 byte-point-min byte-following-char byte-preceding-char
1474 byte-current-column byte-eolp byte-eobp byte-bolp byte-bobp
1475 byte-current-buffer byte-interactive-p))
1480 byte-symbol-value byte-get byte-concat2 byte-concat3 byte-sub1 byte-add1
1481 byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate
1482 byte-plus byte-max byte-min byte-mult byte-char-after byte-char-syntax
1484 byte-member byte-assq byte-quo byte-rem)
1485 byte-compile-side-effect-and-error-free-ops))
1487 ;; This crock is because of the way DEFVAR_BOOL variables work.
1488 ;; Consider the code
1489 ;;
1490 ;; (defun foo (flag)
1491 ;; (let ((old-pop-ups pop-up-windows)
1492 ;; (pop-up-windows flag))
1493 ;; (cond ((not (eq pop-up-windows old-pop-ups))
1494 ;; (setq old-pop-ups pop-up-windows)
1495 ;; ...))))
1496 ;;
1497 ;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is
1498 ;; something else. But if we optimize
1499 ;;
1500 ;; varref flag
1501 ;; varbind pop-up-windows
1502 ;; varref pop-up-windows
1503 ;; not
1504 ;; to
1505 ;; varref flag
1506 ;; dup
1507 ;; varbind pop-up-windows
1508 ;; not
1509 ;;
1510 ;; we break the program, because it will appear that pop-up-windows and
1511 ;; old-pop-ups are not EQ when really they are. So we have to know what
1512 ;; the BOOL variables are, and not perform this optimization on them.
1514 ;; The variable `byte-boolean-vars' is now primitive and updated
1515 ;; automatically by DEFVAR_BOOL.
1518 "Simple peephole optimizer. LAP is both modified and returned.
1519 If FOR-EFFECT is non-nil, the return value is assumed to be of no importance."
1521 lap1
1522 lap2
1525 rest tmp tmp2 tmp3
1527 byte-compile-side-effect-free-ops
1528 byte-compile-side-effect-and-error-free-ops)))
1533 keep-going nil)
1539 ;; You may notice that sequences like "dup varset discard" are
1540 ;; optimized but sequences like "dup varset TAG1: discard" are not.
1541 ;; You may be tempted to change this; resist that temptation.
1543 ;; <side-effect-free> pop --> <deleted>
1544 ;; ...including:
1545 ;; const-X pop --> <deleted>
1546 ;; varref-X pop --> <deleted>
1547 ;; dup pop --> <deleted>
1548 ;;
1568 ;;
1569 ;; goto*-X X: --> X:
1570 ;;
1585 ;;
1586 ;; varset-X varref-X --> dup varset-X
1587 ;; varbind-X varref-X --> dup varbind-X
1588 ;; const/dup varset-X varref-X --> const/dup varset-X const/dup
1589 ;; const/dup varbind-X varref-X --> const/dup varbind-X const/dup
1590 ;; The latter two can enable other optimizations.
1591 ;;
1597 nil
1607 lap0 lap1 lap2 lap0 lap1
1615 ;; The stack depth gets locally increased, so we will
1616 ;; increase maxdepth in case depth = maxdepth here.
1617 ;; This can cause the third argument to byte-code to
1618 ;; be larger than necessary.
1620 ;;
1621 ;; dup varset-X discard --> varset-X
1622 ;; dup varbind-X discard --> varbind-X
1623 ;; (the varbind variant can emerge from other optimizations)
1624 ;;
1632 ;;
1633 ;; not goto-X-if-nil --> goto-X-if-non-nil
1634 ;; not goto-X-if-non-nil --> goto-X-if-nil
1635 ;;
1636 ;; it is wrong to do the same thing for the -else-pop variants.
1637 ;;
1642 lap1
1645 'byte-goto-if-not-nil
1649 'byte-goto-if-not-nil
1653 ;;
1654 ;; goto-X-if-nil goto-Y X: --> goto-Y-if-non-nil X:
1655 ;; goto-X-if-non-nil goto-Y X: --> goto-Y-if-nil X:
1656 ;;
1657 ;; it is wrong to do the same thing for the -else-pop variants.
1658 ;;
1666 lap0 lap1 lap2
1671 ;;
1672 ;; const goto-if-* --> whatever
1673 ;;
1681 lap0 lap1)
1694 ;;
1695 ;; varref-X varref-X --> varref-X dup
1696 ;; varref-X [dup ...] varref-X --> varref-X [dup ...] dup
1697 ;; We don't optimize the const-X variations on this here,
1698 ;; because that would inhibit some goto optimizations; we
1699 ;; optimize the const-X case after all other optimizations.
1700 ;;
1706 t)
1716 lap0 str lap0 lap0 str)))
1721 ;;
1722 ;; TAG1: TAG2: --> TAG1: <deleted>
1723 ;; (and other references to TAG2 are replaced with TAG1)
1724 ;;
1735 keep-going t))
1736 ;;
1737 ;; unused-TAG: --> <deleted>
1738 ;;
1744 keep-going t))
1745 ;;
1746 ;; goto ... --> goto <delete until TAG or end>
1747 ;; return ... --> return <delete until TAG or end>
1748 ;;
1754 str deleted)
1769 lap0
1775 tagstr lap0 tagstr))))
1778 ;;
1779 ;; <safe-op> unbind --> unbind <safe-op>
1780 ;; (this may enable other optimizations.)
1781 ;;
1788 ;;
1789 ;; varbind-X unbind-N --> discard unbind-(N-1)
1790 ;; save-excursion unbind-N --> unbind-(N-1)
1791 ;; save-restriction unbind-N --> unbind-(N-1)
1792 ;;
1795 byte-save-restriction))
1812 ;;
1813 ;; goto*-X ... X: goto-Y --> goto*-Y
1814 ;; goto-X ... X: return --> return
1815 ;;
1828 ;;
1829 ;; goto-*-else-pop X ... X: goto-if-* --> whatever
1830 ;; goto-*-else-pop X ... X: discard --> whatever
1831 ;;
1833 byte-goto-if-not-nil-else-pop))
1840 byte-goto-if-nil)
1842 byte-goto-if-not-nil))))
1848 ;; Get rid of the -else-pop's and jump one step further.
1857 ;;
1858 ;; const goto-X ... X: goto-if-* --> whatever
1859 ;; const goto-X ... X: discard --> whatever
1860 ;;
1872 byte-goto-if-not-nil-else-pop)))
1874 lap0 tmp2 lap0 tmp2)
1877 ;; Let next step fix the (const,goto-if*) sequence.
1880 ;; Jump one step further
1883 lap0 tmp2)
1890 ;;
1891 ;; X: varref-Y ... varset-Y goto-X -->
1892 ;; X: varref-Y Z: ... dup varset-Y goto-Z
1893 ;; (varset-X goto-BACK, BACK: varref-X --> copy the varref down.)
1894 ;; (This is so usual for while loops that it is worth handling).
1895 ;;
1903 ;;(byte-compile-log-lap " Pulled %s to end of loop" (car tmp))
1908 lap1 lap2
1912 )
1917 ;;
1918 ;; goto-X Y: ... X: goto-if*-Y --> goto-if-not-*-X+1 Y:
1919 ;; (This can pull the loop test to the end of the loop)
1920 ;;
1927 byte-goto-if-nil-else-pop)))
1928 ;; (byte-compile-log-lap " %s %s, %s %s --> moved conditional"
1929 ;; lap0 lap1 (cdr lap0) (car tmp))
1938 byte-goto-if-not-nil-else-pop)
1940 byte-goto-if-nil-else-pop))))
1941 newtag)
1944 )
1947 ;; We can handle this case but not the -if-not-nil case,
1948 ;; because we won't know which non-nil constant to push.
1954 byte-goto-if-not-nil
1955 byte-goto-if-nil
1956 byte-goto-if-not-nil
1957 byte-goto byte-goto))))
1958 )
1960 )
1962 )
1963 ;; Cleanup stage:
1964 ;; Rebuild byte-compile-constants / byte-compile-variables.
1965 ;; Simple optimizations that would inhibit other optimizations if they
1966 ;; were done in the optimizing loop, and optimizations which there is no
1967 ;; need to do more than once.
1969 byte-compile-variables nil)
1979 byte-compile-constants)))
1982 byte-compile-variables)))))
1984 ;; const-C varset-X const-C --> const-C dup varset-X
1985 ;; const-C varbind-X const-C --> const-C dup varbind-X
1986 ;;
1992 lap0 lap1 lap0 lap0 lap1)
1996 ;;
1997 ;; const-X [dup/const-X ...] --> const-X [dup ...] dup
1998 ;; varref-X [dup/varref-X ...] --> varref-X [dup ...] dup
1999 ;;
2002 tmp2 nil)
2012 ;;
2013 ;; unbind-N unbind-M --> unbind-(N+M)
2014 ;;
2023 )
2026 lap)
2030 \f
2031 ;; To avoid "lisp nesting exceeds max-lisp-eval-depth" when this file compiles
2032 ;; itself, compile some of its most used recursive functions (at load time).
2033 ;;
2044 byte-optimize-body
2045 byte-optimize-predicate
2046 byte-optimize-binary-predicate
2047 ;; Inserted some more than necessary, to speed it up.
2048 byte-optimize-form-code-walker
2049 byte-optimize-lapcode))))
2050 nil)
2052 ;; arch-tag: 0f14076b-737e-4bef-aae6-908826ec1ff1
2053 ;;; byte-opt.el ends here