| blob | 1ff34fa6a81fb5d353f7c740ea0228e1fde2d812 |
1 ;;; byte-opt.el --- the optimization passes of the emacs-lisp byte compiler
3 ;; Copyright (C) 1991, 1994, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
4 ;; 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
6 ;; Author: Jamie Zawinski <jwz@lucid.com>
7 ;; Hallvard Furuseth <hbf@ulrik.uio.no>
8 ;; Maintainer: FSF
9 ;; Keywords: internal
10 ;; Package: emacs
12 ;; This file is part of GNU Emacs.
14 ;; GNU Emacs is free software: you can redistribute it and/or modify
15 ;; it under the terms of the GNU General Public License as published by
16 ;; the Free Software Foundation, either version 3 of the License, or
17 ;; (at your option) any later version.
19 ;; GNU Emacs is distributed in the hope that it will be useful,
20 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
21 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 ;; GNU General Public License for more details.
24 ;; You should have received a copy of the GNU General Public License
25 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
27 ;;; Commentary:
29 ;; ========================================================================
30 ;; "No matter how hard you try, you can't make a racehorse out of a pig.
31 ;; You can, however, make a faster pig."
32 ;;
33 ;; Or, to put it another way, the Emacs byte compiler is a VW Bug. This code
34 ;; makes it be a VW Bug with fuel injection and a turbocharger... You're
35 ;; still not going to make it go faster than 70 mph, but it might be easier
36 ;; to get it there.
37 ;;
39 ;; TO DO:
40 ;;
41 ;; (apply (lambda (x &rest y) ...) 1 (foo))
42 ;;
43 ;; maintain a list of functions known not to access any global variables
44 ;; (actually, give them a 'dynamically-safe property) and then
45 ;; (let ( v1 v2 ... vM vN ) <...dynamically-safe...> ) ==>
46 ;; (let ( v1 v2 ... vM ) vN <...dynamically-safe...> )
47 ;; by recursing on this, we might be able to eliminate the entire let.
48 ;; However certain variables should never have their bindings optimized
49 ;; away, because they affect everything.
50 ;; (put 'debug-on-error 'binding-is-magic t)
51 ;; (put 'debug-on-abort 'binding-is-magic t)
52 ;; (put 'debug-on-next-call 'binding-is-magic t)
53 ;; (put 'inhibit-quit 'binding-is-magic t)
54 ;; (put 'quit-flag 'binding-is-magic t)
55 ;; (put 't 'binding-is-magic t)
56 ;; (put 'nil 'binding-is-magic t)
57 ;; possibly also
58 ;; (put 'gc-cons-threshold 'binding-is-magic t)
59 ;; (put 'track-mouse 'binding-is-magic t)
60 ;; others?
61 ;;
62 ;; Simple defsubsts often produce forms like
63 ;; (let ((v1 (f1)) (v2 (f2)) ...)
64 ;; (FN v1 v2 ...))
65 ;; It would be nice if we could optimize this to
66 ;; (FN (f1) (f2) ...)
67 ;; but we can't unless FN is dynamically-safe (it might be dynamically
68 ;; referring to the bindings that the lambda arglist established.)
69 ;; One of the uncountable lossages introduced by dynamic scope...
70 ;;
71 ;; Maybe there should be a control-structure that says "turn on
72 ;; fast-and-loose type-assumptive optimizations here." Then when
73 ;; we see a form like (car foo) we can from then on assume that
74 ;; the variable foo is of type cons, and optimize based on that.
75 ;; But, this won't win much because of (you guessed it) dynamic
76 ;; scope. Anything down the stack could change the value.
77 ;; (Another reason it doesn't work is that it is perfectly valid
78 ;; to call car with a null argument.) A better approach might
79 ;; be to allow type-specification of the form
80 ;; (put 'foo 'arg-types '(float (list integer) dynamic))
81 ;; (put 'foo 'result-type 'bool)
82 ;; It should be possible to have these types checked to a certain
83 ;; degree.
84 ;;
85 ;; collapse common subexpressions
86 ;;
87 ;; It would be nice if redundant sequences could be factored out as well,
88 ;; when they are known to have no side-effects:
89 ;; (list (+ a b c) (+ a b c)) --> a b add c add dup list-2
90 ;; but beware of traps like
91 ;; (cons (list x y) (list x y))
92 ;;
93 ;; Tail-recursion elimination is not really possible in Emacs Lisp.
94 ;; Tail-recursion elimination is almost always impossible when all variables
95 ;; have dynamic scope, but given that the "return" byteop requires the
96 ;; binding stack to be empty (rather than emptying it itself), there can be
97 ;; no truly tail-recursive Emacs Lisp functions that take any arguments or
98 ;; make any bindings.
99 ;;
100 ;; Here is an example of an Emacs Lisp function which could safely be
101 ;; byte-compiled tail-recursively:
102 ;;
103 ;; (defun tail-map (fn list)
104 ;; (cond (list
105 ;; (funcall fn (car list))
106 ;; (tail-map fn (cdr list)))))
107 ;;
108 ;; However, if there was even a single let-binding around the COND,
109 ;; it could not be byte-compiled, because there would be an "unbind"
110 ;; byte-op between the final "call" and "return." Adding a
111 ;; Bunbind_all byteop would fix this.
112 ;;
113 ;; (defun foo (x y z) ... (foo a b c))
114 ;; ... (const foo) (varref a) (varref b) (varref c) (call 3) END: (return)
115 ;; ... (varref a) (varbind x) (varref b) (varbind y) (varref c) (varbind z) (goto 0) END: (unbind-all) (return)
116 ;; ... (varref a) (varset x) (varref b) (varset y) (varref c) (varset z) (goto 0) END: (return)
117 ;;
118 ;; this also can be considered tail recursion:
119 ;;
120 ;; ... (const foo) (varref a) (call 1) (goto X) ... X: (return)
121 ;; could generalize this by doing the optimization
122 ;; (goto X) ... X: (return) --> (return)
123 ;;
124 ;; But this doesn't solve all of the problems: although by doing tail-
125 ;; recursion elimination in this way, the call-stack does not grow, the
126 ;; binding-stack would grow with each recursive step, and would eventually
127 ;; overflow. I don't believe there is any way around this without lexical
128 ;; scope.
129 ;;
130 ;; Wouldn't it be nice if Emacs Lisp had lexical scope.
131 ;;
132 ;; Idea: the form (lexical-scope) in a file means that the file may be
133 ;; compiled lexically. This proclamation is file-local. Then, within
134 ;; that file, "let" would establish lexical bindings, and "let-dynamic"
135 ;; would do things the old way. (Or we could use CL "declare" forms.)
136 ;; We'd have to notice defvars and defconsts, since those variables should
137 ;; always be dynamic, and attempting to do a lexical binding of them
138 ;; should simply do a dynamic binding instead.
139 ;; But! We need to know about variables that were not necessarily defvarred
140 ;; in the file being compiled (doing a boundp check isn't good enough.)
141 ;; Fdefvar() would have to be modified to add something to the plist.
142 ;;
143 ;; A major disadvantage of this scheme is that the interpreter and compiler
144 ;; would have different semantics for files compiled with (dynamic-scope).
145 ;; Since this would be a file-local optimization, there would be no way to
146 ;; modify the interpreter to obey this (unless the loader was hacked
147 ;; in some grody way, but that's a really bad idea.)
149 ;; Other things to consider:
151 ;; ;; Associative math should recognize subcalls to identical function:
152 ;; (disassemble (lambda (x) (+ (+ (foo) 1) (+ (bar) 2))))
153 ;; ;; This should generate the same as (1+ x) and (1- x)
155 ;; (disassemble (lambda (x) (cons (+ x 1) (- x 1))))
156 ;; ;; An awful lot of functions always return a non-nil value. If they're
157 ;; ;; error free also they may act as true-constants.
159 ;; (disassemble (lambda (x) (and (point) (foo))))
160 ;; ;; When
161 ;; ;; - all but one arguments to a function are constant
162 ;; ;; - the non-constant argument is an if-expression (cond-expression?)
163 ;; ;; then the outer function can be distributed. If the guarding
164 ;; ;; condition is side-effect-free [assignment-free] then the other
165 ;; ;; arguments may be any expressions. Since, however, the code size
166 ;; ;; can increase this way they should be "simple". Compare:
168 ;; (disassemble (lambda (x) (eq (if (point) 'a 'b) 'c)))
169 ;; (disassemble (lambda (x) (if (point) (eq 'a 'c) (eq 'b 'c))))
171 ;; ;; (car (cons A B)) -> (prog1 A B)
172 ;; (disassemble (lambda (x) (car (cons (foo) 42))))
174 ;; ;; (cdr (cons A B)) -> (progn A B)
175 ;; (disassemble (lambda (x) (cdr (cons 42 (foo)))))
177 ;; ;; (car (list A B ...)) -> (prog1 A B ...)
178 ;; (disassemble (lambda (x) (car (list (foo) 42 (bar)))))
180 ;; ;; (cdr (list A B ...)) -> (progn A (list B ...))
181 ;; (disassemble (lambda (x) (cdr (list 42 (foo) (bar)))))
184 ;;; Code:
200 arg)
216 c
218 args)))))
224 \f
225 ;;; byte-compile optimizers to support inlining
230 "byte-optimize-handler for the `inline' special-form."
243 sexp)))
247 ;; Splice the given lap code into the current instruction stream.
248 ;; If it has any labels in it, you're responsible for making sure there
249 ;; are no collisions, and that byte-compile-tag-number is reasonable
250 ;; after this is spliced in. The provided list is destroyed.
261 name)
262 form)
263 ;; else
276 ;; Isn't it an error for `string' not to be unibyte?? --stef
279 ;; `byte-compile-splice-in-already-compiled-code'
280 ;; takes care of inlining the body.
286 ;; Give up on inlining.
287 form))))))
289 ;; ((lambda ...) ...)
300 optionalp restp
301 bindings)
308 ;; ok, I'll let this slide because funcall_lambda() does...
309 ;; (if optionalp (error "multiple &optional keywords in %s" name))
315 ;; ...but it is by no stretch of the imagination a reasonable
316 ;; thing that funcall_lambda() allows (&rest x y) and
317 ;; (&rest x &optional y) in arglists.
326 bindings)
327 values nil))
333 bindings)
341 form)
343 ;; The following leads to infinite recursion when loading a
344 ;; file containing `(defsubst f () (f))', and then trying to
345 ;; byte-compile that file.
346 ;(setq body (mapcar 'byte-optimize-form body)))
353 newform)))))
355 \f
356 ;;; implementing source-level optimizers
359 ;;
360 ;; For normal function calls, We can just mapcar the optimizer the cdr. But
361 ;; we need to have special knowledge of the syntax of the special forms
362 ;; like let and defun (that's why they're special forms :-). (Actually,
363 ;; the important aspect is that they are subrs that don't evaluate all of
364 ;; their args.)
365 ;;
367 tmp)
373 form))
378 ;; map (quote nil) to nil to simplify optimizer logic.
379 ;; map quoted constants to nil if for-effect (just because).
382 form))
387 for-effect))
389 ;; recursively enter the optimizer for the bindings and body
390 ;; of a let or let*. This for depth-firstness: forms that
391 ;; are more deeply nested are optimized first.
396 binding
413 clause))
416 ;; as an extra added bonus, this simplifies (progn <x>) --> <x>
435 ;; those subrs which have an implicit progn; it's not quite good
436 ;; enough to treat these like normal function calls.
437 ;; This can turn (save-excursion ...) into (save-excursion) which
438 ;; will be optimized away in the lap-optimize pass.
442 ;; this is just like the above, except for the first argument.
458 ;; take forms off the back until we can't any more.
459 ;; In the future it could conceivably be a problem that the
460 ;; subexpressions of these forms are optimized in the reverse
461 ;; order, but it's ok for now.
467 for-effect))))
479 nil)
482 condition-case save-window-excursion))
483 ;; These forms are compiled as constants or by breaking out
484 ;; all the subexpressions and compiling them separately.
485 form)
488 ;; the "protected" part of an unwind-protect is compiled (and thus
489 ;; optimized) as a top-level form, so don't do it here. But the
490 ;; non-protected part has the same for-effect status as the
491 ;; unwind-protect itself. (The protected part is always for effect,
492 ;; but that isn't handled properly yet.)
498 ;; the body of a catch is compiled (and thus optimized) as a
499 ;; top-level form, so don't do it here. The tag is never
500 ;; for-effect. The body should have the same for-effect status
501 ;; as the catch form itself, but that isn't handled properly yet.
507 ;; Don't treat the args to `ignore' as being
508 ;; computed for effect. We want to avoid the warnings
509 ;; that might occur if they were treated that way.
510 ;; However, don't actually bother calling `ignore'.
513 ;; If optimization is on, this is the only place that macros are
514 ;; expanded. If optimization is off, then macroexpansion happens
515 ;; in byte-compile-form. Otherwise, the macros are already expanded
516 ;; by the time that is reached.
519 byte-compile-macro-environment))))
522 ;; Support compiler macros as in cl.el.
534 form)
539 ;; Detect the expansion of (pop foo).
540 ;; There is no need to compile the call to `car' there.
554 nil)))
556 ;; appending a nil here might not be necessary, but it can't hurt.
561 ;; Otherwise, no args can be considered to be for-effect,
562 ;; even if the called function is for-effect, because we
563 ;; don't know anything about that function.
571 "Non-nil if all elements of LIST satisfy `byte-compile-constp'."
577 constant))
580 "The source-level pass of the optimizer."
581 ;;
582 ;; First, optimize all sub-forms of this one.
584 ;;
585 ;; after optimizing all subforms, optimize this form until it doesn't
586 ;; optimize any further. This means that some forms will be passed through
587 ;; the optimizer many times, but that's necessary to make the for-effect
588 ;; processing do as much as possible.
589 ;;
594 ;; we don't have any of these yet, but we might.
599 ;; (if (equal form new) (error "bogus optimizer -- %s" opt))
602 new)
603 form)))
607 ;; optimize the cdr of a progn or implicit progn; all forms is a list of
608 ;; forms, all but the last of which are optimized with the assumption that
609 ;; they are being called for effect. the last is for-effect as well if
610 ;; all-for-effect is true. returns a new list of forms.
613 fe new)
622 \f
623 ;; some source-level optimizers
624 ;;
625 ;; when writing optimizers, be VERY careful that the optimizer returns
626 ;; something not EQ to its argument if and ONLY if it has made a change.
627 ;; This implies that you cannot simply destructively modify the list;
628 ;; you must return something not EQ to it if you make an optimization.
629 ;;
630 ;; It is now safe to optimize code such that it introduces new bindings.
633 "Return non-nil if FORM always evaluates to a non-nil value."
639 ;; Can't use recursion in a defsubst.
640 ;; (progn (byte-compile-trueconstp (car (last (cdr form)))))
641 ))
647 "Return non-nil if FORM always evaluates to a nil value."
653 ;; Can't use recursion in a defsubst.
654 ;; (progn (byte-compile-nilconstp (car (last (cdr form)))))
655 ))
659 ;; If the function is being called with constant numeric args,
660 ;; evaluate as much as possible at compile-time. This optimizer
661 ;; assumes that the function is associative, like + or *.
679 form)))
681 ;; If the function is being called with constant numeric args,
682 ;; evaluate as much as possible at compile-time. This optimizer
683 ;; assumes that the function satisfies
684 ;; (op x1 x2 ... xn) == (op ...(op (op x1 x2) x3) ...xn)
685 ;; like - and /.
689 form
697 constant))))
699 ;;(defun byte-optimize-associative-two-args-math (form)
700 ;; (setq form (byte-optimize-associative-math form))
701 ;; (if (consp form)
702 ;; (byte-optimize-two-args-left form)
703 ;; form))
705 ;;(defun byte-optimize-nonassociative-two-args-math (form)
706 ;; (setq form (byte-optimize-nonassociative-math form))
707 ;; (if (consp form)
708 ;; (byte-optimize-two-args-right form)
709 ;; form))
714 ;; Collect all the constants from FORM, after the STARTth arg,
715 ;; and apply FUN to them to make one argument at the end.
716 ;; For functions that can handle floats, that optimization
717 ;; can be incorrect because reordering can cause an overflow
718 ;; that would otherwise be avoided by encountering an arg that is a float.
719 ;; We avoid this problem by (1) not moving float constants and
720 ;; (2) not moving anything if it would cause an overflow.
722 ;; Merge all FORM's constants from number START, call FUN on them
723 ;; and put the result at the end.
726 ;; t means we must check for overflow.
737 ;; If necessary, check now for overflow
738 ;; that might be caused by reordering.
740 ;; We have overflow if the result of doing the arithmetic
741 ;; on floats is not even close to the result
742 ;; of doing it on integers.
749 form))
755 ;; Don't call `byte-optimize-delay-constants-math' (bug#1334).
756 ;;(setq form (byte-optimize-delay-constants-math form 1 '+))
758 ;; For (+ constants...), byte-optimize-predicate does the work.
761 ;; (+ x 1) --> (1+ x) and (+ x -1) --> (1- x).
771 ;; Here, we could also do
772 ;; (+ x y ... 1) --> (1+ (+ x y ...))
773 ;; (+ x y ... -1) --> (1- (+ x y ...))
774 ;; The resulting bytecode is smaller, but is it faster? -- cyd
775 ))
779 ;; Don't call `byte-optimize-delay-constants-math' (bug#1334).
780 ;;(setq form (byte-optimize-delay-constants-math form 2 '+))
781 ;; Remove zeros.
786 ;; After the above, we must turn (- x) back into (- x 0)
789 ;; For (- constants..), byte-optimize-predicate does the work.
792 ;; (- x 1) --> (1- x)
795 ;; (- x -1) --> (1+ x)
798 ;; (- 0 x) --> (- x)
802 ;; Here, we could also do
803 ;; (- x y ... 1) --> (1- (- x y ...))
804 ;; (- x y ... -1) --> (1+ (- x y ...))
805 ;; The resulting bytecode is smaller, but is it faster? -- cyd
806 ))
811 ;; For (* constants..), byte-optimize-predicate does the work.
813 ;; After `byte-optimize-predicate', if there is a INTEGER constant
814 ;; in FORM, it is in the last element.
817 ;; Would handling (* ... 0) here cause floating point errors?
818 ;; See bug#1334.
828 ;; After `byte-optimize-predicate', if there is a INTEGER constant
829 ;; in FORM, it is in the last element.
832 ;; Runtime error (leave it intact).
836 ;; No constants in expression
838 ;; For (* constants..), byte-optimize-predicate does the work.
840 ;; (/ x y.. 1) --> (/ x y..)
843 ;; (/ x -1), (/ x .. -1) --> (- x), (- (/ x ..))
869 ;; This can enable some lapcode optimizations.
871 form))
883 form)))
891 form))
935 ;; I'm not convinced that this is necessary. Doesn't the optimizer loop
936 ;; take care of this? - Jamie
937 ;; I think this may some times be necessary to reduce ie (quote 5) to 5,
938 ;; so arithmetic optimizers recognize the numeric constant. - Hallvard
944 form
957 ;; Simplify if less than 2 args.
958 ;; if there is a literal nil in the args to `and', throw it and following
959 ;; forms away, and surround the `and' with (progn ... nil).
968 nil))
974 ;; Throw away nil's, and simplify if less than 2 args.
975 ;; If there is a literal non-nil constant in the args to `or', throw away all
976 ;; following forms.
989 ;; if any clauses have a literal nil as their test, throw them away.
990 ;; if any clause has a literal non-nil constant as its test, throw
991 ;; away all following clauses.
993 ;; This must be first, to reduce (cond (t ...) (nil)) to (progn t ...)
1001 ;; This branch will always be taken: kill the subsequent ones.
1010 ;; This branch will never be taken: kill its body.
1012 ;;
1013 ;; Turn (cond (( <x> )) ... ) into (or <x> (cond ... ))
1021 form))
1022 form))
1025 ;; (if (progn <insts> <test>) <rest>) ==> (progn <insts> (if <test> <rest>))
1026 ;; (if <true-constant> <then> <else...>) ==> <then>
1027 ;; (if <false-constant> <then> <else...>) ==> (progn <else...>)
1028 ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>))
1029 ;; (if <test> <then> nil) ==> (if <test> <then>)
1032 ;; `clause' is a proper list.
1035 ;; A trivial `progn'.
1048 form))
1051 ;; Don't make a double negative;
1052 ;; instead, take away the one that is there.
1067 form))
1075 ;; byte-compile-negation-optimizer lives in bytecomp.el
1082 ;; (funcall (lambda ...) ...) ==> ((lambda ...) ...)
1083 ;; (funcall foo ...) ==> (foo ...)
1087 form)))
1090 ;; If the last arg is a literal constant, turn this into a funcall.
1091 ;; The funcall optimizer can then transform (funcall 'foo ...) -> (foo ...).
1101 "last arg to apply can't be a literal atom: `%s'"
1103 nil))
1104 form)))
1114 ;; No bindings
1117 form)
1118 ;; The body is nil
1135 form))
1145 form)
1147 form))
1149 ;; Fixme: delete-char -> delete-region (byte-coded)
1150 ;; optimize string-as-unibyte, string-as-multibyte, string-make-unibyte,
1151 ;; string-make-multibyte for constant args.
1155 ;; Emacs-21's byte-code doesn't run under XEmacs or SXEmacs anyway, so we
1156 ;; can safely optimize away this test.
1158 nil
1160 t
1161 form)))
1174 \f
1175 ;; enumerating those functions which need not be called if the returned
1176 ;; value is not used. That is, something like
1177 ;; (progn (list (something-with-side-effects) (yow))
1178 ;; (foo))
1179 ;; may safely be turned into
1180 ;; (progn (progn (something-with-side-effects) (yow))
1181 ;; (foo))
1182 ;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo.
1184 ;; Some of these functions have the side effect of allocating memory
1185 ;; and it would be incorrect to replace two calls with one.
1186 ;; But we don't try to do those kinds of optimizations,
1187 ;; so it is safe to list such functions here.
1188 ;; Some of these functions return values that depend on environment
1189 ;; state, so that constant folding them would be wrong,
1190 ;; but we don't do constant folding based on this list.
1192 ;; However, at present the only optimization we normally do
1193 ;; is delete calls that need not occur, and we only do that
1194 ;; with the error-free functions.
1196 ;; I wonder if I missed any :-\)
1199 assoc assq
1200 boundp buffer-file-name buffer-local-variables buffer-modified-p
1201 buffer-substring byte-code-function-p
1202 capitalize car-less-than-car car cdr ceiling char-after char-before
1203 char-equal char-to-string char-width
1204 compare-strings concat coordinates-in-window-p
1205 copy-alist copy-sequence copy-marker cos count-lines
1206 decode-char
1207 decode-time default-boundp default-value documentation downcase
1208 elt encode-char exp expt encode-time error-message-string
1209 fboundp fceiling featurep ffloor
1210 file-directory-p file-exists-p file-locked-p file-name-absolute-p
1211 file-newer-than-file-p file-readable-p file-symlink-p file-writable-p
1212 float float-time floor format format-time-string frame-visible-p
1213 fround ftruncate
1214 get gethash get-buffer get-buffer-window getenv get-file-buffer
1215 hash-table-count
1216 int-to-string intern-soft
1217 keymap-parent
1218 length local-variable-if-set-p local-variable-p log log10 logand
1219 logb logior lognot logxor lsh langinfo
1220 make-list make-string make-symbol
1221 marker-buffer max member memq min mod multibyte-char-to-unibyte
1222 next-window nth nthcdr number-to-string
1223 parse-colon-path plist-get plist-member
1224 prefix-numeric-value previous-window prin1-to-string propertize
1225 degrees-to-radians
1226 radians-to-degrees rassq rassoc read-from-string regexp-quote
1227 region-beginning region-end reverse round
1229 string-to-int string-to-number substring sxhash symbol-function
1230 symbol-name symbol-plist symbol-value string-make-unibyte
1231 string-make-multibyte string-as-multibyte string-as-unibyte
1232 string-to-multibyte
1233 tan truncate
1234 unibyte-char-to-multibyte upcase user-full-name
1235 user-login-name user-original-login-name user-variable-p
1236 vconcat
1237 window-buffer window-dedicated-p window-edges window-height
1238 window-hscroll window-minibuffer-p window-width
1239 zerop))
1242 bobp bolp bool-vector-p
1243 buffer-end buffer-list buffer-size buffer-string bufferp
1244 car-safe case-table-p cdr-safe char-or-string-p characterp
1245 charsetp commandp cons consp
1246 current-buffer current-global-map current-indentation
1247 current-local-map current-minor-mode-maps current-time
1248 current-time-string current-time-zone
1249 eobp eolp eq equal eventp
1250 floatp following-char framep
1251 get-largest-window get-lru-window
1252 hash-table-p
1253 identity ignore integerp integer-or-marker-p interactive-p
1254 invocation-directory invocation-name
1255 keymapp
1256 line-beginning-position line-end-position list listp
1257 make-marker mark mark-marker markerp max-char
1258 memory-limit minibuffer-window
1259 mouse-movement-p
1260 natnump nlistp not null number-or-marker-p numberp
1261 one-window-p overlayp
1262 point point-marker point-min point-max preceding-char primary-charset
1263 processp
1264 recent-keys recursion-depth
1265 safe-length selected-frame selected-window sequencep
1266 standard-case-table standard-syntax-table stringp subrp symbolp
1267 syntax-table syntax-table-p
1268 this-command-keys this-command-keys-vector this-single-command-keys
1269 this-single-command-raw-keys
1270 user-real-login-name user-real-uid user-uid
1271 vector vectorp visible-frame-list
1272 wholenump window-configuration-p window-live-p windowp)))
1279 nil)
1281 \f
1282 ;; pure functions are side-effect free functions whose values depend
1283 ;; only on their arguments. For these functions, calls with constant
1284 ;; arguments can be evaluated at compile time. This may shift run time
1285 ;; errors to compile time.
1292 nil)
1295 ;; form is (byte-code "..." [...] n)
1301 byte-compile-maxdepth))
1306 \f
1310 ;; This function extracts the bitfields from variable-length opcodes.
1311 ;; Originally defined in disass.el (which no longer uses it.)
1314 "Don't call this!"
1315 ;; fetch and return the offset for the current opcode.
1316 ;; return nil if this opcode has no offset
1317 ;; OP, PTR and BYTES are used and set dynamically
1348 ;; This de-compiler is used for inline expansion of compiled functions,
1349 ;; and by the disassembler.
1350 ;;
1351 ;; This list contains numbers, which are pc values,
1352 ;; before each instruction.
1354 "Turn BYTECODE into lapcode, referring to CONSTVEC."
1360 ;; As byte-decompile-bytecode, but updates
1361 ;; byte-compile-{constants, variables, tag-number}.
1362 ;; If MAKE-SPLICEABLE is true, then `return' opcodes are replaced
1363 ;; with `goto's destined for the end of the code.
1364 ;; That is for use by the compiler.
1365 ;; If MAKE-SPLICEABLE is nil, we are being called for the disassembler.
1366 ;; In that case, we put a pc value into the list
1367 ;; before each insn (or its label).
1371 lap tmp
1372 endtag)
1377 optr ptr
1381 ;; it's a pc
1387 tags)))))))
1398 byte-compile-variables)))))))
1405 ;; lap = ( [ (pc . (op . arg)) ]* )
1407 lap))
1409 ;; take off the dummy nil op that we replaced a trailing "return" with.
1414 ;; this addr is jumped to
1425 ;; remove addrs, lap = ( [ (op . arg) | (TAG tagno) ]* )
1428 elt
1432 \f
1433 ;;; peephole optimizer
1439 byte-goto-if-not-nil-else-pop))
1443 byte-symbolp byte-consp byte-stringp byte-listp byte-numberp byte-integerp
1444 byte-eq byte-not
1445 byte-cons byte-list1 byte-list2 ; byte-list3 byte-list4
1446 byte-interactive-p)
1447 ;; How about other side-effect-free-ops? Is it safe to move an
1448 ;; error invocation (such as from nth) out of an unwind-protect?
1449 ;; No, it is not, because the unwind-protect forms can alter
1450 ;; the inside of the object to which nth would apply.
1451 ;; For the same reason, byte-equal was deleted from this list.
1456 byte-integerp byte-numberp byte-eq byte-equal byte-not byte-car-safe
1457 byte-cdr-safe byte-cons byte-list1 byte-list2 byte-point byte-point-max
1458 byte-point-min byte-following-char byte-preceding-char
1459 byte-current-column byte-eolp byte-eobp byte-bolp byte-bobp
1460 byte-current-buffer byte-interactive-p))
1465 byte-symbol-value byte-get byte-concat2 byte-concat3 byte-sub1 byte-add1
1466 byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate
1467 byte-plus byte-max byte-min byte-mult byte-char-after byte-char-syntax
1469 byte-member byte-assq byte-quo byte-rem)
1470 byte-compile-side-effect-and-error-free-ops))
1472 ;; This crock is because of the way DEFVAR_BOOL variables work.
1473 ;; Consider the code
1474 ;;
1475 ;; (defun foo (flag)
1476 ;; (let ((old-pop-ups pop-up-windows)
1477 ;; (pop-up-windows flag))
1478 ;; (cond ((not (eq pop-up-windows old-pop-ups))
1479 ;; (setq old-pop-ups pop-up-windows)
1480 ;; ...))))
1481 ;;
1482 ;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is
1483 ;; something else. But if we optimize
1484 ;;
1485 ;; varref flag
1486 ;; varbind pop-up-windows
1487 ;; varref pop-up-windows
1488 ;; not
1489 ;; to
1490 ;; varref flag
1491 ;; dup
1492 ;; varbind pop-up-windows
1493 ;; not
1494 ;;
1495 ;; we break the program, because it will appear that pop-up-windows and
1496 ;; old-pop-ups are not EQ when really they are. So we have to know what
1497 ;; the BOOL variables are, and not perform this optimization on them.
1499 ;; The variable `byte-boolean-vars' is now primitive and updated
1500 ;; automatically by DEFVAR_BOOL.
1503 "Simple peephole optimizer. LAP is both modified and returned.
1504 If FOR-EFFECT is non-nil, the return value is assumed to be of no importance."
1506 lap1
1507 lap2
1510 rest tmp tmp2 tmp3
1512 byte-compile-side-effect-free-ops
1513 byte-compile-side-effect-and-error-free-ops)))
1518 keep-going nil)
1524 ;; You may notice that sequences like "dup varset discard" are
1525 ;; optimized but sequences like "dup varset TAG1: discard" are not.
1526 ;; You may be tempted to change this; resist that temptation.
1528 ;; <side-effect-free> pop --> <deleted>
1529 ;; ...including:
1530 ;; const-X pop --> <deleted>
1531 ;; varref-X pop --> <deleted>
1532 ;; dup pop --> <deleted>
1533 ;;
1553 ;;
1554 ;; goto*-X X: --> X:
1555 ;;
1570 ;;
1571 ;; varset-X varref-X --> dup varset-X
1572 ;; varbind-X varref-X --> dup varbind-X
1573 ;; const/dup varset-X varref-X --> const/dup varset-X const/dup
1574 ;; const/dup varbind-X varref-X --> const/dup varbind-X const/dup
1575 ;; The latter two can enable other optimizations.
1576 ;;
1582 nil
1592 lap0 lap1 lap2 lap0 lap1
1600 ;; The stack depth gets locally increased, so we will
1601 ;; increase maxdepth in case depth = maxdepth here.
1602 ;; This can cause the third argument to byte-code to
1603 ;; be larger than necessary.
1605 ;;
1606 ;; dup varset-X discard --> varset-X
1607 ;; dup varbind-X discard --> varbind-X
1608 ;; (the varbind variant can emerge from other optimizations)
1609 ;;
1617 ;;
1618 ;; not goto-X-if-nil --> goto-X-if-non-nil
1619 ;; not goto-X-if-non-nil --> goto-X-if-nil
1620 ;;
1621 ;; it is wrong to do the same thing for the -else-pop variants.
1622 ;;
1627 lap1
1630 'byte-goto-if-not-nil
1634 'byte-goto-if-not-nil
1638 ;;
1639 ;; goto-X-if-nil goto-Y X: --> goto-Y-if-non-nil X:
1640 ;; goto-X-if-non-nil goto-Y X: --> goto-Y-if-nil X:
1641 ;;
1642 ;; it is wrong to do the same thing for the -else-pop variants.
1643 ;;
1651 lap0 lap1 lap2
1656 ;;
1657 ;; const goto-if-* --> whatever
1658 ;;
1666 lap0 lap1)
1679 ;;
1680 ;; varref-X varref-X --> varref-X dup
1681 ;; varref-X [dup ...] varref-X --> varref-X [dup ...] dup
1682 ;; We don't optimize the const-X variations on this here,
1683 ;; because that would inhibit some goto optimizations; we
1684 ;; optimize the const-X case after all other optimizations.
1685 ;;
1691 t)
1701 lap0 str lap0 lap0 str)))
1706 ;;
1707 ;; TAG1: TAG2: --> TAG1: <deleted>
1708 ;; (and other references to TAG2 are replaced with TAG1)
1709 ;;
1720 keep-going t))
1721 ;;
1722 ;; unused-TAG: --> <deleted>
1723 ;;
1729 keep-going t))
1730 ;;
1731 ;; goto ... --> goto <delete until TAG or end>
1732 ;; return ... --> return <delete until TAG or end>
1733 ;;
1739 str deleted)
1754 lap0
1760 tagstr lap0 tagstr))))
1763 ;;
1764 ;; <safe-op> unbind --> unbind <safe-op>
1765 ;; (this may enable other optimizations.)
1766 ;;
1773 ;;
1774 ;; varbind-X unbind-N --> discard unbind-(N-1)
1775 ;; save-excursion unbind-N --> unbind-(N-1)
1776 ;; save-restriction unbind-N --> unbind-(N-1)
1777 ;;
1780 byte-save-restriction))
1797 ;;
1798 ;; goto*-X ... X: goto-Y --> goto*-Y
1799 ;; goto-X ... X: return --> return
1800 ;;
1813 ;;
1814 ;; goto-*-else-pop X ... X: goto-if-* --> whatever
1815 ;; goto-*-else-pop X ... X: discard --> whatever
1816 ;;
1818 byte-goto-if-not-nil-else-pop))
1825 byte-goto-if-nil)
1827 byte-goto-if-not-nil))))
1833 ;; Get rid of the -else-pop's and jump one step further.
1842 ;;
1843 ;; const goto-X ... X: goto-if-* --> whatever
1844 ;; const goto-X ... X: discard --> whatever
1845 ;;
1857 byte-goto-if-not-nil-else-pop)))
1859 lap0 tmp2 lap0 tmp2)
1862 ;; Let next step fix the (const,goto-if*) sequence.
1865 ;; Jump one step further
1868 lap0 tmp2)
1875 ;;
1876 ;; X: varref-Y ... varset-Y goto-X -->
1877 ;; X: varref-Y Z: ... dup varset-Y goto-Z
1878 ;; (varset-X goto-BACK, BACK: varref-X --> copy the varref down.)
1879 ;; (This is so usual for while loops that it is worth handling).
1880 ;;
1888 ;;(byte-compile-log-lap " Pulled %s to end of loop" (car tmp))
1893 lap1 lap2
1897 )
1902 ;;
1903 ;; goto-X Y: ... X: goto-if*-Y --> goto-if-not-*-X+1 Y:
1904 ;; (This can pull the loop test to the end of the loop)
1905 ;;
1912 byte-goto-if-nil-else-pop)))
1913 ;; (byte-compile-log-lap " %s %s, %s %s --> moved conditional"
1914 ;; lap0 lap1 (cdr lap0) (car tmp))
1923 byte-goto-if-not-nil-else-pop)
1925 byte-goto-if-nil-else-pop))))
1926 newtag)
1929 )
1932 ;; We can handle this case but not the -if-not-nil case,
1933 ;; because we won't know which non-nil constant to push.
1939 byte-goto-if-not-nil
1940 byte-goto-if-nil
1941 byte-goto-if-not-nil
1942 byte-goto byte-goto))))
1943 )
1945 )
1947 )
1948 ;; Cleanup stage:
1949 ;; Rebuild byte-compile-constants / byte-compile-variables.
1950 ;; Simple optimizations that would inhibit other optimizations if they
1951 ;; were done in the optimizing loop, and optimizations which there is no
1952 ;; need to do more than once.
1954 byte-compile-variables nil)
1964 byte-compile-constants)))
1967 byte-compile-variables)))))
1969 ;; const-C varset-X const-C --> const-C dup varset-X
1970 ;; const-C varbind-X const-C --> const-C dup varbind-X
1971 ;;
1977 lap0 lap1 lap0 lap0 lap1)
1981 ;;
1982 ;; const-X [dup/const-X ...] --> const-X [dup ...] dup
1983 ;; varref-X [dup/varref-X ...] --> varref-X [dup ...] dup
1984 ;;
1987 tmp2 nil)
1997 ;;
1998 ;; unbind-N unbind-M --> unbind-(N+M)
1999 ;;
2008 )
2011 lap)
2015 \f
2016 ;; To avoid "lisp nesting exceeds max-lisp-eval-depth" when this file compiles
2017 ;; itself, compile some of its most used recursive functions (at load time).
2018 ;;
2029 byte-optimize-body
2030 byte-optimize-predicate
2031 byte-optimize-binary-predicate
2032 ;; Inserted some more than necessary, to speed it up.
2033 byte-optimize-form-code-walker
2034 byte-optimize-lapcode))))
2035 nil)
2037 ;; arch-tag: 0f14076b-737e-4bef-aae6-908826ec1ff1
2038 ;;; byte-opt.el ends here