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- ;;; byte-opt.el --- the optimization passes of the emacs-lisp byte compiler -*- lexical-binding: t -*-
- ;; Copyright (C) 1991, 1994, 2000-2017 Free Software Foundation, Inc.
- ;; Author: Jamie Zawinski <jwz@lucid.com>
- ;; Hallvard Furuseth <hbf@ulrik.uio.no>
- ;; Maintainer: emacs-devel@gnu.org
- ;; Keywords: internal
- ;; Package: emacs
- ;; This file is part of GNU Emacs.
- ;; GNU Emacs is free software: you can redistribute it and/or modify
- ;; it under the terms of the GNU General Public License as published by
- ;; the Free Software Foundation, either version 3 of the License, or
- ;; (at your option) any later version.
- ;; GNU Emacs is distributed in the hope that it will be useful,
- ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
- ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- ;; GNU General Public License for more details.
- ;; You should have received a copy of the GNU General Public License
- ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
- ;;; Commentary:
- ;; ========================================================================
- ;; "No matter how hard you try, you can't make a racehorse out of a pig.
- ;; You can, however, make a faster pig."
- ;;
- ;; Or, to put it another way, the Emacs byte compiler is a VW Bug. This code
- ;; makes it be a VW Bug with fuel injection and a turbocharger... You're
- ;; still not going to make it go faster than 70 mph, but it might be easier
- ;; to get it there.
- ;;
- ;; TO DO:
- ;;
- ;; (apply (lambda (x &rest y) ...) 1 (foo))
- ;;
- ;; maintain a list of functions known not to access any global variables
- ;; (actually, give them a 'dynamically-safe property) and then
- ;; (let ( v1 v2 ... vM vN ) <...dynamically-safe...> ) ==>
- ;; (let ( v1 v2 ... vM ) vN <...dynamically-safe...> )
- ;; by recursing on this, we might be able to eliminate the entire let.
- ;; However certain variables should never have their bindings optimized
- ;; away, because they affect everything.
- ;; (put 'debug-on-error 'binding-is-magic t)
- ;; (put 'debug-on-abort 'binding-is-magic t)
- ;; (put 'debug-on-next-call 'binding-is-magic t)
- ;; (put 'inhibit-quit 'binding-is-magic t)
- ;; (put 'quit-flag 'binding-is-magic t)
- ;; (put 't 'binding-is-magic t)
- ;; (put 'nil 'binding-is-magic t)
- ;; possibly also
- ;; (put 'gc-cons-threshold 'binding-is-magic t)
- ;; (put 'track-mouse 'binding-is-magic t)
- ;; others?
- ;;
- ;; Simple defsubsts often produce forms like
- ;; (let ((v1 (f1)) (v2 (f2)) ...)
- ;; (FN v1 v2 ...))
- ;; It would be nice if we could optimize this to
- ;; (FN (f1) (f2) ...)
- ;; but we can't unless FN is dynamically-safe (it might be dynamically
- ;; referring to the bindings that the lambda arglist established.)
- ;; One of the uncountable lossages introduced by dynamic scope...
- ;;
- ;; Maybe there should be a control-structure that says "turn on
- ;; fast-and-loose type-assumptive optimizations here." Then when
- ;; we see a form like (car foo) we can from then on assume that
- ;; the variable foo is of type cons, and optimize based on that.
- ;; But, this won't win much because of (you guessed it) dynamic
- ;; scope. Anything down the stack could change the value.
- ;; (Another reason it doesn't work is that it is perfectly valid
- ;; to call car with a null argument.) A better approach might
- ;; be to allow type-specification of the form
- ;; (put 'foo 'arg-types '(float (list integer) dynamic))
- ;; (put 'foo 'result-type 'bool)
- ;; It should be possible to have these types checked to a certain
- ;; degree.
- ;;
- ;; collapse common subexpressions
- ;;
- ;; It would be nice if redundant sequences could be factored out as well,
- ;; when they are known to have no side-effects:
- ;; (list (+ a b c) (+ a b c)) --> a b add c add dup list-2
- ;; but beware of traps like
- ;; (cons (list x y) (list x y))
- ;;
- ;; Tail-recursion elimination is not really possible in Emacs Lisp.
- ;; Tail-recursion elimination is almost always impossible when all variables
- ;; have dynamic scope, but given that the "return" byteop requires the
- ;; binding stack to be empty (rather than emptying it itself), there can be
- ;; no truly tail-recursive Emacs Lisp functions that take any arguments or
- ;; make any bindings.
- ;;
- ;; Here is an example of an Emacs Lisp function which could safely be
- ;; byte-compiled tail-recursively:
- ;;
- ;; (defun tail-map (fn list)
- ;; (cond (list
- ;; (funcall fn (car list))
- ;; (tail-map fn (cdr list)))))
- ;;
- ;; However, if there was even a single let-binding around the COND,
- ;; it could not be byte-compiled, because there would be an "unbind"
- ;; byte-op between the final "call" and "return." Adding a
- ;; Bunbind_all byteop would fix this.
- ;;
- ;; (defun foo (x y z) ... (foo a b c))
- ;; ... (const foo) (varref a) (varref b) (varref c) (call 3) END: (return)
- ;; ... (varref a) (varbind x) (varref b) (varbind y) (varref c) (varbind z) (goto 0) END: (unbind-all) (return)
- ;; ... (varref a) (varset x) (varref b) (varset y) (varref c) (varset z) (goto 0) END: (return)
- ;;
- ;; this also can be considered tail recursion:
- ;;
- ;; ... (const foo) (varref a) (call 1) (goto X) ... X: (return)
- ;; could generalize this by doing the optimization
- ;; (goto X) ... X: (return) --> (return)
- ;;
- ;; But this doesn't solve all of the problems: although by doing tail-
- ;; recursion elimination in this way, the call-stack does not grow, the
- ;; binding-stack would grow with each recursive step, and would eventually
- ;; overflow. I don't believe there is any way around this without lexical
- ;; scope.
- ;;
- ;; Wouldn't it be nice if Emacs Lisp had lexical scope.
- ;;
- ;; Idea: the form (lexical-scope) in a file means that the file may be
- ;; compiled lexically. This proclamation is file-local. Then, within
- ;; that file, "let" would establish lexical bindings, and "let-dynamic"
- ;; would do things the old way. (Or we could use CL "declare" forms.)
- ;; We'd have to notice defvars and defconsts, since those variables should
- ;; always be dynamic, and attempting to do a lexical binding of them
- ;; should simply do a dynamic binding instead.
- ;; But! We need to know about variables that were not necessarily defvared
- ;; in the file being compiled (doing a boundp check isn't good enough.)
- ;; Fdefvar() would have to be modified to add something to the plist.
- ;;
- ;; A major disadvantage of this scheme is that the interpreter and compiler
- ;; would have different semantics for files compiled with (dynamic-scope).
- ;; Since this would be a file-local optimization, there would be no way to
- ;; modify the interpreter to obey this (unless the loader was hacked
- ;; in some grody way, but that's a really bad idea.)
- ;; Other things to consider:
- ;; ;; Associative math should recognize subcalls to identical function:
- ;; (disassemble (lambda (x) (+ (+ (foo) 1) (+ (bar) 2))))
- ;; ;; This should generate the same as (1+ x) and (1- x)
- ;; (disassemble (lambda (x) (cons (+ x 1) (- x 1))))
- ;; ;; An awful lot of functions always return a non-nil value. If they're
- ;; ;; error free also they may act as true-constants.
- ;; (disassemble (lambda (x) (and (point) (foo))))
- ;; ;; When
- ;; ;; - all but one arguments to a function are constant
- ;; ;; - the non-constant argument is an if-expression (cond-expression?)
- ;; ;; then the outer function can be distributed. If the guarding
- ;; ;; condition is side-effect-free [assignment-free] then the other
- ;; ;; arguments may be any expressions. Since, however, the code size
- ;; ;; can increase this way they should be "simple". Compare:
- ;; (disassemble (lambda (x) (eq (if (point) 'a 'b) 'c)))
- ;; (disassemble (lambda (x) (if (point) (eq 'a 'c) (eq 'b 'c))))
- ;; ;; (car (cons A B)) -> (prog1 A B)
- ;; (disassemble (lambda (x) (car (cons (foo) 42))))
- ;; ;; (cdr (cons A B)) -> (progn A B)
- ;; (disassemble (lambda (x) (cdr (cons 42 (foo)))))
- ;; ;; (car (list A B ...)) -> (prog1 A B ...)
- ;; (disassemble (lambda (x) (car (list (foo) 42 (bar)))))
- ;; ;; (cdr (list A B ...)) -> (progn A (list B ...))
- ;; (disassemble (lambda (x) (cdr (list 42 (foo) (bar)))))
- ;;; Code:
- (require 'bytecomp)
- (eval-when-compile (require 'cl-lib))
- (require 'macroexp)
- (eval-when-compile (require 'subr-x))
- (defun byte-compile-log-lap-1 (format &rest args)
- ;; Newer byte codes for stack-ref make the slot 0 non-nil again.
- ;; But the "old disassembler" is *really* ancient by now.
- ;; (if (aref byte-code-vector 0)
- ;; (error "The old version of the disassembler is loaded. Reload new-bytecomp as well"))
- (byte-compile-log-1
- (apply #'format-message format
- (let (c a)
- (mapcar (lambda (arg)
- (if (not (consp arg))
- (if (and (symbolp arg)
- (string-match "^byte-" (symbol-name arg)))
- (intern (substring (symbol-name arg) 5))
- arg)
- (if (integerp (setq c (car arg)))
- (error "non-symbolic byte-op %s" c))
- (if (eq c 'TAG)
- (setq c arg)
- (setq a (cond ((memq c byte-goto-ops)
- (car (cdr (cdr arg))))
- ((memq c byte-constref-ops)
- (car (cdr arg)))
- (t (cdr arg))))
- (setq c (symbol-name c))
- (if (string-match "^byte-." c)
- (setq c (intern (substring c 5)))))
- (if (eq c 'constant) (setq c 'const))
- (if (and (eq (cdr arg) 0)
- (not (memq c '(unbind call const))))
- c
- (format "(%s %s)" c a))))
- args)))))
- (defmacro byte-compile-log-lap (format-string &rest args)
- `(and (memq byte-optimize-log '(t byte))
- (byte-compile-log-lap-1 ,format-string ,@args)))
- ;;; byte-compile optimizers to support inlining
- (put 'inline 'byte-optimizer 'byte-optimize-inline-handler)
- (defun byte-optimize-inline-handler (form)
- "byte-optimize-handler for the `inline' special-form."
- (cons 'progn
- (mapcar
- (lambda (sexp)
- (let ((f (car-safe sexp)))
- (if (and (symbolp f)
- (or (cdr (assq f byte-compile-function-environment))
- (not (or (not (fboundp f))
- (cdr (assq f byte-compile-macro-environment))
- (and (consp (setq f (symbol-function f)))
- (eq (car f) 'macro))
- (subrp f)))))
- (byte-compile-inline-expand sexp)
- sexp)))
- (cdr form))))
- (defun byte-compile-inline-expand (form)
- (let* ((name (car form))
- (localfn (cdr (assq name byte-compile-function-environment)))
- (fn (or localfn (symbol-function name))))
- (when (autoloadp fn)
- (autoload-do-load fn)
- (setq fn (or (symbol-function name)
- (cdr (assq name byte-compile-function-environment)))))
- (pcase fn
- (`nil
- (byte-compile-warn "attempt to inline `%s' before it was defined"
- name)
- form)
- (`(autoload . ,_)
- (error "File `%s' didn't define `%s'" (nth 1 fn) name))
- ((and (pred symbolp) (guard (not (eq fn t)))) ;A function alias.
- (byte-compile-inline-expand (cons fn (cdr form))))
- ((pred byte-code-function-p)
- ;; (message "Inlining byte-code for %S!" name)
- ;; The byte-code will be really inlined in byte-compile-unfold-bcf.
- `(,fn ,@(cdr form)))
- ((or `(lambda . ,_) `(closure . ,_))
- (if (not (or (eq fn localfn) ;From the same file => same mode.
- (eq (car fn) ;Same mode.
- (if lexical-binding 'closure 'lambda))))
- ;; While byte-compile-unfold-bcf can inline dynbind byte-code into
- ;; letbind byte-code (or any other combination for that matter), we
- ;; can only inline dynbind source into dynbind source or letbind
- ;; source into letbind source.
- (progn
- ;; We can of course byte-compile the inlined function
- ;; first, and then inline its byte-code.
- (byte-compile name)
- `(,(symbol-function name) ,@(cdr form)))
- (let ((newfn (if (eq fn localfn)
- ;; If `fn' is from the same file, it has already
- ;; been preprocessed!
- `(function ,fn)
- (byte-compile-preprocess
- (byte-compile--reify-function fn)))))
- (if (eq (car-safe newfn) 'function)
- (byte-compile-unfold-lambda `(,(cadr newfn) ,@(cdr form)))
- ;; This can happen because of macroexp-warn-and-return &co.
- (byte-compile-warn
- "Inlining closure %S failed" name)
- form))))
- (_ ;; Give up on inlining.
- form))))
- ;; ((lambda ...) ...)
- (defun byte-compile-unfold-lambda (form &optional name)
- ;; In lexical-binding mode, let and functions don't bind vars in the same way
- ;; (let obey special-variable-p, but functions don't). But luckily, this
- ;; doesn't matter here, because function's behavior is underspecified so it
- ;; can safely be turned into a `let', even though the reverse is not true.
- (or name (setq name "anonymous lambda"))
- (let* ((lambda (car form))
- (values (cdr form))
- (arglist (nth 1 lambda))
- (body (cdr (cdr lambda)))
- optionalp restp
- bindings)
- (if (and (stringp (car body)) (cdr body))
- (setq body (cdr body)))
- (if (and (consp (car body)) (eq 'interactive (car (car body))))
- (setq body (cdr body)))
- ;; FIXME: The checks below do not belong in an optimization phase.
- (while arglist
- (cond ((eq (car arglist) '&optional)
- ;; ok, I'll let this slide because funcall_lambda() does...
- ;; (if optionalp (error "multiple &optional keywords in %s" name))
- (if restp (error "&optional found after &rest in %s" name))
- (if (null (cdr arglist))
- (error "nothing after &optional in %s" name))
- (setq optionalp t))
- ((eq (car arglist) '&rest)
- ;; ...but it is by no stretch of the imagination a reasonable
- ;; thing that funcall_lambda() allows (&rest x y) and
- ;; (&rest x &optional y) in arglists.
- (if (null (cdr arglist))
- (error "nothing after &rest in %s" name))
- (if (cdr (cdr arglist))
- (error "multiple vars after &rest in %s" name))
- (setq restp t))
- (restp
- (setq bindings (cons (list (car arglist)
- (and values (cons 'list values)))
- bindings)
- values nil))
- ((and (not optionalp) (null values))
- (byte-compile-warn "attempt to open-code `%s' with too few arguments" name)
- (setq arglist nil values 'too-few))
- (t
- (setq bindings (cons (list (car arglist) (car values))
- bindings)
- values (cdr values))))
- (setq arglist (cdr arglist)))
- (if values
- (progn
- (or (eq values 'too-few)
- (byte-compile-warn
- "attempt to open-code `%s' with too many arguments" name))
- form)
- ;; The following leads to infinite recursion when loading a
- ;; file containing `(defsubst f () (f))', and then trying to
- ;; byte-compile that file.
- ;(setq body (mapcar 'byte-optimize-form body)))
- (let ((newform
- (if bindings
- (cons 'let (cons (nreverse bindings) body))
- (cons 'progn body))))
- (byte-compile-log " %s\t==>\t%s" form newform)
- newform))))
- ;;; implementing source-level optimizers
- (defun byte-optimize-form-code-walker (form for-effect)
- ;;
- ;; For normal function calls, We can just mapcar the optimizer the cdr. But
- ;; we need to have special knowledge of the syntax of the special forms
- ;; like let and defun (that's why they're special forms :-). (Actually,
- ;; the important aspect is that they are subrs that don't evaluate all of
- ;; their args.)
- ;;
- (let ((fn (car-safe form))
- tmp)
- (cond ((not (consp form))
- (if (not (and for-effect
- (or byte-compile-delete-errors
- (not (symbolp form))
- (eq form t))))
- form))
- ((eq fn 'quote)
- (if (cdr (cdr form))
- (byte-compile-warn "malformed quote form: `%s'"
- (prin1-to-string form)))
- ;; map (quote nil) to nil to simplify optimizer logic.
- ;; map quoted constants to nil if for-effect (just because).
- (and (nth 1 form)
- (not for-effect)
- form))
- ((eq (car-safe fn) 'lambda)
- (let ((newform (byte-compile-unfold-lambda form)))
- (if (eq newform form)
- ;; Some error occurred, avoid infinite recursion
- form
- (byte-optimize-form-code-walker newform for-effect))))
- ((eq (car-safe fn) 'closure) form)
- ((memq fn '(let let*))
- ;; recursively enter the optimizer for the bindings and body
- ;; of a let or let*. This for depth-firstness: forms that
- ;; are more deeply nested are optimized first.
- (cons fn
- (cons
- (mapcar (lambda (binding)
- (if (symbolp binding)
- binding
- (if (cdr (cdr binding))
- (byte-compile-warn "malformed let binding: `%s'"
- (prin1-to-string binding)))
- (list (car binding)
- (byte-optimize-form (nth 1 binding) nil))))
- (nth 1 form))
- (byte-optimize-body (cdr (cdr form)) for-effect))))
- ((eq fn 'cond)
- (cons fn
- (mapcar (lambda (clause)
- (if (consp clause)
- (cons
- (byte-optimize-form (car clause) nil)
- (byte-optimize-body (cdr clause) for-effect))
- (byte-compile-warn "malformed cond form: `%s'"
- (prin1-to-string clause))
- clause))
- (cdr form))))
- ((eq fn 'progn)
- ;; As an extra added bonus, this simplifies (progn <x>) --> <x>.
- (if (cdr (cdr form))
- (macroexp-progn (byte-optimize-body (cdr form) for-effect))
- (byte-optimize-form (nth 1 form) for-effect)))
- ((eq fn 'prog1)
- (if (cdr (cdr form))
- (cons 'prog1
- (cons (byte-optimize-form (nth 1 form) for-effect)
- (byte-optimize-body (cdr (cdr form)) t)))
- (byte-optimize-form (nth 1 form) for-effect)))
- ((eq fn 'prog2)
- (cons 'prog2
- (cons (byte-optimize-form (nth 1 form) t)
- (cons (byte-optimize-form (nth 2 form) for-effect)
- (byte-optimize-body (cdr (cdr (cdr form))) t)))))
- ((memq fn '(save-excursion save-restriction save-current-buffer))
- ;; those subrs which have an implicit progn; it's not quite good
- ;; enough to treat these like normal function calls.
- ;; This can turn (save-excursion ...) into (save-excursion) which
- ;; will be optimized away in the lap-optimize pass.
- (cons fn (byte-optimize-body (cdr form) for-effect)))
- ((eq fn 'with-output-to-temp-buffer)
- ;; this is just like the above, except for the first argument.
- (cons fn
- (cons
- (byte-optimize-form (nth 1 form) nil)
- (byte-optimize-body (cdr (cdr form)) for-effect))))
- ((eq fn 'if)
- (when (< (length form) 3)
- (byte-compile-warn "too few arguments for `if'"))
- (cons fn
- (cons (byte-optimize-form (nth 1 form) nil)
- (cons
- (byte-optimize-form (nth 2 form) for-effect)
- (byte-optimize-body (nthcdr 3 form) for-effect)))))
- ((memq fn '(and or)) ; Remember, and/or are control structures.
- ;; Take forms off the back until we can't any more.
- ;; In the future it could conceivably be a problem that the
- ;; subexpressions of these forms are optimized in the reverse
- ;; order, but it's ok for now.
- (if for-effect
- (let ((backwards (reverse (cdr form))))
- (while (and backwards
- (null (setcar backwards
- (byte-optimize-form (car backwards)
- for-effect))))
- (setq backwards (cdr backwards)))
- (if (and (cdr form) (null backwards))
- (byte-compile-log
- " all subforms of %s called for effect; deleted" form))
- (and backwards
- (cons fn (nreverse (mapcar 'byte-optimize-form
- backwards)))))
- (cons fn (mapcar 'byte-optimize-form (cdr form)))))
- ((eq fn 'interactive)
- (byte-compile-warn "misplaced interactive spec: `%s'"
- (prin1-to-string form))
- nil)
- ((eq fn 'function)
- ;; This forms is compiled as constant or by breaking out
- ;; all the subexpressions and compiling them separately.
- form)
- ((eq fn 'condition-case)
- (if byte-compile--use-old-handlers
- ;; Will be optimized later.
- form
- `(condition-case ,(nth 1 form) ;Not evaluated.
- ,(byte-optimize-form (nth 2 form) for-effect)
- ,@(mapcar (lambda (clause)
- `(,(car clause)
- ,@(byte-optimize-body (cdr clause) for-effect)))
- (nthcdr 3 form)))))
- ((eq fn 'unwind-protect)
- ;; the "protected" part of an unwind-protect is compiled (and thus
- ;; optimized) as a top-level form, so don't do it here. But the
- ;; non-protected part has the same for-effect status as the
- ;; unwind-protect itself. (The protected part is always for effect,
- ;; but that isn't handled properly yet.)
- (cons fn
- (cons (byte-optimize-form (nth 1 form) for-effect)
- (cdr (cdr form)))))
- ((eq fn 'catch)
- (cons fn
- (cons (byte-optimize-form (nth 1 form) nil)
- (if byte-compile--use-old-handlers
- ;; The body of a catch is compiled (and thus
- ;; optimized) as a top-level form, so don't do it
- ;; here.
- (cdr (cdr form))
- (byte-optimize-body (cdr form) for-effect)))))
- ((eq fn 'ignore)
- ;; Don't treat the args to `ignore' as being
- ;; computed for effect. We want to avoid the warnings
- ;; that might occur if they were treated that way.
- ;; However, don't actually bother calling `ignore'.
- `(prog1 nil . ,(mapcar 'byte-optimize-form (cdr form))))
- ;; Needed as long as we run byte-optimize-form after cconv.
- ((eq fn 'internal-make-closure) form)
- ((byte-code-function-p fn)
- (cons fn (mapcar #'byte-optimize-form (cdr form))))
- ((not (symbolp fn))
- (byte-compile-warn "`%s' is a malformed function"
- (prin1-to-string fn))
- form)
- ((and for-effect (setq tmp (get fn 'side-effect-free))
- (or byte-compile-delete-errors
- (eq tmp 'error-free)
- (progn
- (byte-compile-warn "value returned from %s is unused"
- (prin1-to-string form))
- nil)))
- (byte-compile-log " %s called for effect; deleted" fn)
- ;; appending a nil here might not be necessary, but it can't hurt.
- (byte-optimize-form
- (cons 'progn (append (cdr form) '(nil))) t))
- (t
- ;; Otherwise, no args can be considered to be for-effect,
- ;; even if the called function is for-effect, because we
- ;; don't know anything about that function.
- (let ((args (mapcar #'byte-optimize-form (cdr form))))
- (if (and (get fn 'pure)
- (byte-optimize-all-constp args))
- (list 'quote (apply fn (mapcar #'eval args)))
- (cons fn args)))))))
- (defun byte-optimize-all-constp (list)
- "Non-nil if all elements of LIST satisfy `macroexp-const-p'."
- (let ((constant t))
- (while (and list constant)
- (unless (macroexp-const-p (car list))
- (setq constant nil))
- (setq list (cdr list)))
- constant))
- (defun byte-optimize-form (form &optional for-effect)
- "The source-level pass of the optimizer."
- ;;
- ;; First, optimize all sub-forms of this one.
- (setq form (byte-optimize-form-code-walker form for-effect))
- ;;
- ;; after optimizing all subforms, optimize this form until it doesn't
- ;; optimize any further. This means that some forms will be passed through
- ;; the optimizer many times, but that's necessary to make the for-effect
- ;; processing do as much as possible.
- ;;
- (let (opt new)
- (if (and (consp form)
- (symbolp (car form))
- (or ;; (and for-effect
- ;; ;; We don't have any of these yet, but we might.
- ;; (setq opt (get (car form)
- ;; 'byte-for-effect-optimizer)))
- (setq opt (function-get (car form) 'byte-optimizer)))
- (not (eq form (setq new (funcall opt form)))))
- (progn
- ;; (if (equal form new) (error "bogus optimizer -- %s" opt))
- (byte-compile-log " %s\t==>\t%s" form new)
- (setq new (byte-optimize-form new for-effect))
- new)
- form)))
- (defun byte-optimize-body (forms all-for-effect)
- ;; Optimize the cdr of a progn or implicit progn; all forms is a list of
- ;; forms, all but the last of which are optimized with the assumption that
- ;; they are being called for effect. the last is for-effect as well if
- ;; all-for-effect is true. returns a new list of forms.
- (let ((rest forms)
- (result nil)
- fe new)
- (while rest
- (setq fe (or all-for-effect (cdr rest)))
- (setq new (and (car rest) (byte-optimize-form (car rest) fe)))
- (if (or new (not fe))
- (setq result (cons new result)))
- (setq rest (cdr rest)))
- (nreverse result)))
- ;; some source-level optimizers
- ;;
- ;; when writing optimizers, be VERY careful that the optimizer returns
- ;; something not EQ to its argument if and ONLY if it has made a change.
- ;; This implies that you cannot simply destructively modify the list;
- ;; you must return something not EQ to it if you make an optimization.
- ;;
- ;; It is now safe to optimize code such that it introduces new bindings.
- (defsubst byte-compile-trueconstp (form)
- "Return non-nil if FORM always evaluates to a non-nil value."
- (while (eq (car-safe form) 'progn)
- (setq form (car (last (cdr form)))))
- (cond ((consp form)
- (pcase (car form)
- (`quote (cadr form))
- ;; Can't use recursion in a defsubst.
- ;; (`progn (byte-compile-trueconstp (car (last (cdr form)))))
- ))
- ((not (symbolp form)))
- ((eq form t))
- ((keywordp form))))
- (defsubst byte-compile-nilconstp (form)
- "Return non-nil if FORM always evaluates to a nil value."
- (while (eq (car-safe form) 'progn)
- (setq form (car (last (cdr form)))))
- (cond ((consp form)
- (pcase (car form)
- (`quote (null (cadr form)))
- ;; Can't use recursion in a defsubst.
- ;; (`progn (byte-compile-nilconstp (car (last (cdr form)))))
- ))
- ((not (symbolp form)) nil)
- ((null form))))
- ;; If the function is being called with constant numeric args,
- ;; evaluate as much as possible at compile-time. This optimizer
- ;; assumes that the function is associative, like + or *.
- (defun byte-optimize-associative-math (form)
- (let ((args nil)
- (constants nil)
- (rest (cdr form)))
- (while rest
- (if (numberp (car rest))
- (setq constants (cons (car rest) constants))
- (setq args (cons (car rest) args)))
- (setq rest (cdr rest)))
- (if (cdr constants)
- (if args
- (list (car form)
- (apply (car form) constants)
- (if (cdr args)
- (cons (car form) (nreverse args))
- (car args)))
- (apply (car form) constants))
- form)))
- ;; If the function is being called with constant numeric args,
- ;; evaluate as much as possible at compile-time. This optimizer
- ;; assumes that the function satisfies
- ;; (op x1 x2 ... xn) == (op ...(op (op x1 x2) x3) ...xn)
- ;; like - and /.
- (defun byte-optimize-nonassociative-math (form)
- (if (or (not (numberp (car (cdr form))))
- (not (numberp (car (cdr (cdr form))))))
- form
- (let ((constant (car (cdr form)))
- (rest (cdr (cdr form))))
- (while (numberp (car rest))
- (setq constant (funcall (car form) constant (car rest))
- rest (cdr rest)))
- (if rest
- (cons (car form) (cons constant rest))
- constant))))
- ;;(defun byte-optimize-associative-two-args-math (form)
- ;; (setq form (byte-optimize-associative-math form))
- ;; (if (consp form)
- ;; (byte-optimize-two-args-left form)
- ;; form))
- ;;(defun byte-optimize-nonassociative-two-args-math (form)
- ;; (setq form (byte-optimize-nonassociative-math form))
- ;; (if (consp form)
- ;; (byte-optimize-two-args-right form)
- ;; form))
- (defun byte-optimize-approx-equal (x y)
- (<= (* (abs (- x y)) 100) (abs (+ x y))))
- ;; Collect all the constants from FORM, after the STARTth arg,
- ;; and apply FUN to them to make one argument at the end.
- ;; For functions that can handle floats, that optimization
- ;; can be incorrect because reordering can cause an overflow
- ;; that would otherwise be avoided by encountering an arg that is a float.
- ;; We avoid this problem by (1) not moving float constants and
- ;; (2) not moving anything if it would cause an overflow.
- (defun byte-optimize-delay-constants-math (form start fun)
- ;; Merge all FORM's constants from number START, call FUN on them
- ;; and put the result at the end.
- (let ((rest (nthcdr (1- start) form))
- (orig form)
- ;; t means we must check for overflow.
- (overflow (memq fun '(+ *))))
- (while (cdr (setq rest (cdr rest)))
- (if (integerp (car rest))
- (let (constants)
- (setq form (copy-sequence form)
- rest (nthcdr (1- start) form))
- (while (setq rest (cdr rest))
- (cond ((integerp (car rest))
- (setq constants (cons (car rest) constants))
- (setcar rest nil))))
- ;; If necessary, check now for overflow
- ;; that might be caused by reordering.
- (if (and overflow
- ;; We have overflow if the result of doing the arithmetic
- ;; on floats is not even close to the result
- ;; of doing it on integers.
- (not (byte-optimize-approx-equal
- (apply fun (mapcar 'float constants))
- (float (apply fun constants)))))
- (setq form orig)
- (setq form (nconc (delq nil form)
- (list (apply fun (nreverse constants)))))))))
- form))
- (defsubst byte-compile-butlast (form)
- (nreverse (cdr (reverse form))))
- (defun byte-optimize-plus (form)
- ;; Don't call `byte-optimize-delay-constants-math' (bug#1334).
- ;;(setq form (byte-optimize-delay-constants-math form 1 '+))
- (if (memq 0 form) (setq form (delq 0 (copy-sequence form))))
- ;; For (+ constants...), byte-optimize-predicate does the work.
- (when (memq nil (mapcar 'numberp (cdr form)))
- (cond
- ;; (+ x 1) --> (1+ x) and (+ x -1) --> (1- x).
- ((and (= (length form) 3)
- (or (memq (nth 1 form) '(1 -1))
- (memq (nth 2 form) '(1 -1))))
- (let (integer other)
- (if (memq (nth 1 form) '(1 -1))
- (setq integer (nth 1 form) other (nth 2 form))
- (setq integer (nth 2 form) other (nth 1 form)))
- (setq form
- (list (if (eq integer 1) '1+ '1-) other))))
- ;; Here, we could also do
- ;; (+ x y ... 1) --> (1+ (+ x y ...))
- ;; (+ x y ... -1) --> (1- (+ x y ...))
- ;; The resulting bytecode is smaller, but is it faster? -- cyd
- ))
- (byte-optimize-predicate form))
- (defun byte-optimize-minus (form)
- ;; Don't call `byte-optimize-delay-constants-math' (bug#1334).
- ;;(setq form (byte-optimize-delay-constants-math form 2 '+))
- ;; Remove zeros.
- (when (and (nthcdr 3 form)
- (memq 0 (cddr form)))
- (setq form (nconc (list (car form) (cadr form))
- (delq 0 (copy-sequence (cddr form)))))
- ;; After the above, we must turn (- x) back into (- x 0)
- (or (cddr form)
- (setq form (nconc form (list 0)))))
- ;; For (- constants..), byte-optimize-predicate does the work.
- (when (memq nil (mapcar 'numberp (cdr form)))
- (cond
- ;; (- x 1) --> (1- x)
- ((equal (nthcdr 2 form) '(1))
- (setq form (list '1- (nth 1 form))))
- ;; (- x -1) --> (1+ x)
- ((equal (nthcdr 2 form) '(-1))
- (setq form (list '1+ (nth 1 form))))
- ;; (- 0 x) --> (- x)
- ((and (eq (nth 1 form) 0)
- (= (length form) 3))
- (setq form (list '- (nth 2 form))))
- ;; Here, we could also do
- ;; (- x y ... 1) --> (1- (- x y ...))
- ;; (- x y ... -1) --> (1+ (- x y ...))
- ;; The resulting bytecode is smaller, but is it faster? -- cyd
- ))
- (byte-optimize-predicate form))
- (defun byte-optimize-multiply (form)
- (setq form (byte-optimize-delay-constants-math form 1 '*))
- ;; For (* constants..), byte-optimize-predicate does the work.
- (when (memq nil (mapcar 'numberp (cdr form)))
- ;; After `byte-optimize-predicate', if there is a INTEGER constant
- ;; in FORM, it is in the last element.
- (let ((last (car (reverse (cdr form)))))
- (cond
- ;; Would handling (* ... 0) here cause floating point errors?
- ;; See bug#1334.
- ((eq 1 last) (setq form (byte-compile-butlast form)))
- ((eq -1 last)
- (setq form (list '- (if (nthcdr 3 form)
- (byte-compile-butlast form)
- (nth 1 form))))))))
- (byte-optimize-predicate form))
- (defun byte-optimize-divide (form)
- (setq form (byte-optimize-delay-constants-math form 2 '*))
- ;; After `byte-optimize-predicate', if there is a INTEGER constant
- ;; in FORM, it is in the last element.
- (let ((last (car (reverse (cdr (cdr form))))))
- (cond
- ;; Runtime error (leave it intact).
- ((or (null last)
- (eq last 0)
- (memql 0.0 (cddr form))))
- ;; No constants in expression
- ((not (numberp last)))
- ;; For (* constants..), byte-optimize-predicate does the work.
- ((null (memq nil (mapcar 'numberp (cdr form)))))
- ;; (/ x y.. 1) --> (/ x y..)
- ((and (eq last 1) (nthcdr 3 form))
- (setq form (byte-compile-butlast form)))
- ;; (/ x -1), (/ x .. -1) --> (- x), (- (/ x ..))
- ((eq last -1)
- (setq form (list '- (if (nthcdr 3 form)
- (byte-compile-butlast form)
- (nth 1 form)))))))
- (byte-optimize-predicate form))
- (defun byte-optimize-logmumble (form)
- (setq form (byte-optimize-delay-constants-math form 1 (car form)))
- (byte-optimize-predicate
- (cond ((memq 0 form)
- (setq form (if (eq (car form) 'logand)
- (cons 'progn (cdr form))
- (delq 0 (copy-sequence form)))))
- ((and (eq (car-safe form) 'logior)
- (memq -1 form))
- (cons 'progn (cdr form)))
- (form))))
- (defun byte-optimize-binary-predicate (form)
- (cond
- ((or (not (macroexp-const-p (nth 1 form)))
- (nthcdr 3 form)) ;; In case there are more than 2 args.
- form)
- ((macroexp-const-p (nth 2 form))
- (condition-case ()
- (list 'quote (eval form))
- (error form)))
- (t ;; This can enable some lapcode optimizations.
- (list (car form) (nth 2 form) (nth 1 form)))))
- (defun byte-optimize-predicate (form)
- (let ((ok t)
- (rest (cdr form)))
- (while (and rest ok)
- (setq ok (macroexp-const-p (car rest))
- rest (cdr rest)))
- (if ok
- (condition-case ()
- (list 'quote (eval form))
- (error form))
- form)))
- (defun byte-optimize-identity (form)
- (if (and (cdr form) (null (cdr (cdr form))))
- (nth 1 form)
- (byte-compile-warn "identity called with %d arg%s, but requires 1"
- (length (cdr form))
- (if (= 1 (length (cdr form))) "" "s"))
- form))
- (put 'identity 'byte-optimizer 'byte-optimize-identity)
- (put '+ 'byte-optimizer 'byte-optimize-plus)
- (put '* 'byte-optimizer 'byte-optimize-multiply)
- (put '- 'byte-optimizer 'byte-optimize-minus)
- (put '/ 'byte-optimizer 'byte-optimize-divide)
- (put 'max 'byte-optimizer 'byte-optimize-associative-math)
- (put 'min 'byte-optimizer 'byte-optimize-associative-math)
- (put '= 'byte-optimizer 'byte-optimize-binary-predicate)
- (put 'eq 'byte-optimizer 'byte-optimize-binary-predicate)
- (put 'equal 'byte-optimizer 'byte-optimize-binary-predicate)
- (put 'string= 'byte-optimizer 'byte-optimize-binary-predicate)
- (put 'string-equal 'byte-optimizer 'byte-optimize-binary-predicate)
- (put '< 'byte-optimizer 'byte-optimize-predicate)
- (put '> 'byte-optimizer 'byte-optimize-predicate)
- (put '<= 'byte-optimizer 'byte-optimize-predicate)
- (put '>= 'byte-optimizer 'byte-optimize-predicate)
- (put '1+ 'byte-optimizer 'byte-optimize-predicate)
- (put '1- 'byte-optimizer 'byte-optimize-predicate)
- (put 'not 'byte-optimizer 'byte-optimize-predicate)
- (put 'null 'byte-optimizer 'byte-optimize-predicate)
- (put 'memq 'byte-optimizer 'byte-optimize-predicate)
- (put 'consp 'byte-optimizer 'byte-optimize-predicate)
- (put 'listp 'byte-optimizer 'byte-optimize-predicate)
- (put 'symbolp 'byte-optimizer 'byte-optimize-predicate)
- (put 'stringp 'byte-optimizer 'byte-optimize-predicate)
- (put 'string< 'byte-optimizer 'byte-optimize-predicate)
- (put 'string-lessp 'byte-optimizer 'byte-optimize-predicate)
- (put 'logand 'byte-optimizer 'byte-optimize-logmumble)
- (put 'logior 'byte-optimizer 'byte-optimize-logmumble)
- (put 'logxor 'byte-optimizer 'byte-optimize-logmumble)
- (put 'lognot 'byte-optimizer 'byte-optimize-predicate)
- (put 'car 'byte-optimizer 'byte-optimize-predicate)
- (put 'cdr 'byte-optimizer 'byte-optimize-predicate)
- (put 'car-safe 'byte-optimizer 'byte-optimize-predicate)
- (put 'cdr-safe 'byte-optimizer 'byte-optimize-predicate)
- ;; I'm not convinced that this is necessary. Doesn't the optimizer loop
- ;; take care of this? - Jamie
- ;; I think this may some times be necessary to reduce ie (quote 5) to 5,
- ;; so arithmetic optimizers recognize the numeric constant. - Hallvard
- (put 'quote 'byte-optimizer 'byte-optimize-quote)
- (defun byte-optimize-quote (form)
- (if (or (consp (nth 1 form))
- (and (symbolp (nth 1 form))
- (not (macroexp--const-symbol-p form))))
- form
- (nth 1 form)))
- (defun byte-optimize-and (form)
- ;; Simplify if less than 2 args.
- ;; if there is a literal nil in the args to `and', throw it and following
- ;; forms away, and surround the `and' with (progn ... nil).
- (cond ((null (cdr form)))
- ((memq nil form)
- (list 'progn
- (byte-optimize-and
- (prog1 (setq form (copy-sequence form))
- (while (nth 1 form)
- (setq form (cdr form)))
- (setcdr form nil)))
- nil))
- ((null (cdr (cdr form)))
- (nth 1 form))
- ((byte-optimize-predicate form))))
- (defun byte-optimize-or (form)
- ;; Throw away nil's, and simplify if less than 2 args.
- ;; If there is a literal non-nil constant in the args to `or', throw away all
- ;; following forms.
- (if (memq nil form)
- (setq form (delq nil (copy-sequence form))))
- (let ((rest form))
- (while (cdr (setq rest (cdr rest)))
- (if (byte-compile-trueconstp (car rest))
- (setq form (copy-sequence form)
- rest (setcdr (memq (car rest) form) nil))))
- (if (cdr (cdr form))
- (byte-optimize-predicate form)
- (nth 1 form))))
- (defun byte-optimize-cond (form)
- ;; if any clauses have a literal nil as their test, throw them away.
- ;; if any clause has a literal non-nil constant as its test, throw
- ;; away all following clauses.
- (let (rest)
- ;; This must be first, to reduce (cond (t ...) (nil)) to (progn t ...)
- (while (setq rest (assq nil (cdr form)))
- (setq form (delq rest (copy-sequence form))))
- (if (memq nil (cdr form))
- (setq form (delq nil (copy-sequence form))))
- (setq rest form)
- (while (setq rest (cdr rest))
- (cond ((byte-compile-trueconstp (car-safe (car rest)))
- ;; This branch will always be taken: kill the subsequent ones.
- (cond ((eq rest (cdr form)) ;First branch of `cond'.
- (setq form `(progn ,@(car rest))))
- ((cdr rest)
- (setq form (copy-sequence form))
- (setcdr (memq (car rest) form) nil)))
- (setq rest nil))
- ((and (consp (car rest))
- (byte-compile-nilconstp (caar rest)))
- ;; This branch will never be taken: kill its body.
- (setcdr (car rest) nil)))))
- ;;
- ;; Turn (cond (( <x> )) ... ) into (or <x> (cond ... ))
- (if (eq 'cond (car-safe form))
- (let ((clauses (cdr form)))
- (if (and (consp (car clauses))
- (null (cdr (car clauses))))
- (list 'or (car (car clauses))
- (byte-optimize-cond
- (cons (car form) (cdr (cdr form)))))
- form))
- form))
- (defun byte-optimize-if (form)
- ;; (if (progn <insts> <test>) <rest>) ==> (progn <insts> (if <test> <rest>))
- ;; (if <true-constant> <then> <else...>) ==> <then>
- ;; (if <false-constant> <then> <else...>) ==> (progn <else...>)
- ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>))
- ;; (if <test> <then> nil) ==> (if <test> <then>)
- (let ((clause (nth 1 form)))
- (cond ((and (eq (car-safe clause) 'progn)
- ;; `clause' is a proper list.
- (null (cdr (last clause))))
- (if (null (cddr clause))
- ;; A trivial `progn'.
- (byte-optimize-if `(if ,(cadr clause) ,@(nthcdr 2 form)))
- (nconc (butlast clause)
- (list
- (byte-optimize-if
- `(if ,(car (last clause)) ,@(nthcdr 2 form)))))))
- ((byte-compile-trueconstp clause)
- `(progn ,clause ,(nth 2 form)))
- ((byte-compile-nilconstp clause)
- `(progn ,clause ,@(nthcdr 3 form)))
- ((nth 2 form)
- (if (equal '(nil) (nthcdr 3 form))
- (list 'if clause (nth 2 form))
- form))
- ((or (nth 3 form) (nthcdr 4 form))
- (list 'if
- ;; Don't make a double negative;
- ;; instead, take away the one that is there.
- (if (and (consp clause) (memq (car clause) '(not null))
- (= (length clause) 2)) ; (not xxxx) or (not (xxxx))
- (nth 1 clause)
- (list 'not clause))
- (if (nthcdr 4 form)
- (cons 'progn (nthcdr 3 form))
- (nth 3 form))))
- (t
- (list 'progn clause nil)))))
- (defun byte-optimize-while (form)
- (when (< (length form) 2)
- (byte-compile-warn "too few arguments for `while'"))
- (if (nth 1 form)
- form))
- (put 'and 'byte-optimizer 'byte-optimize-and)
- (put 'or 'byte-optimizer 'byte-optimize-or)
- (put 'cond 'byte-optimizer 'byte-optimize-cond)
- (put 'if 'byte-optimizer 'byte-optimize-if)
- (put 'while 'byte-optimizer 'byte-optimize-while)
- ;; byte-compile-negation-optimizer lives in bytecomp.el
- (put '/= 'byte-optimizer 'byte-compile-negation-optimizer)
- (put 'atom 'byte-optimizer 'byte-compile-negation-optimizer)
- (put 'nlistp 'byte-optimizer 'byte-compile-negation-optimizer)
- (defun byte-optimize-funcall (form)
- ;; (funcall (lambda ...) ...) ==> ((lambda ...) ...)
- ;; (funcall foo ...) ==> (foo ...)
- (let ((fn (nth 1 form)))
- (if (memq (car-safe fn) '(quote function))
- (cons (nth 1 fn) (cdr (cdr form)))
- form)))
- (defun byte-optimize-apply (form)
- ;; If the last arg is a literal constant, turn this into a funcall.
- ;; The funcall optimizer can then transform (funcall 'foo ...) -> (foo ...).
- (let ((fn (nth 1 form))
- (last (nth (1- (length form)) form))) ; I think this really is fastest
- (or (if (or (null last)
- (eq (car-safe last) 'quote))
- (if (listp (nth 1 last))
- (let ((butlast (nreverse (cdr (reverse (cdr (cdr form)))))))
- (nconc (list 'funcall fn) butlast
- (mapcar (lambda (x) (list 'quote x)) (nth 1 last))))
- (byte-compile-warn
- "last arg to apply can't be a literal atom: `%s'"
- (prin1-to-string last))
- nil))
- form)))
- (put 'funcall 'byte-optimizer 'byte-optimize-funcall)
- (put 'apply 'byte-optimizer 'byte-optimize-apply)
- (put 'let 'byte-optimizer 'byte-optimize-letX)
- (put 'let* 'byte-optimizer 'byte-optimize-letX)
- (defun byte-optimize-letX (form)
- (cond ((null (nth 1 form))
- ;; No bindings
- (cons 'progn (cdr (cdr form))))
- ((or (nth 2 form) (nthcdr 3 form))
- form)
- ;; The body is nil
- ((eq (car form) 'let)
- (append '(progn) (mapcar 'car-safe (mapcar 'cdr-safe (nth 1 form)))
- '(nil)))
- (t
- (let ((binds (reverse (nth 1 form))))
- (list 'let* (reverse (cdr binds)) (nth 1 (car binds)) nil)))))
- (put 'nth 'byte-optimizer 'byte-optimize-nth)
- (defun byte-optimize-nth (form)
- (if (= (safe-length form) 3)
- (if (memq (nth 1 form) '(0 1))
- (list 'car (if (zerop (nth 1 form))
- (nth 2 form)
- (list 'cdr (nth 2 form))))
- (byte-optimize-predicate form))
- form))
- (put 'nthcdr 'byte-optimizer 'byte-optimize-nthcdr)
- (defun byte-optimize-nthcdr (form)
- (if (= (safe-length form) 3)
- (if (memq (nth 1 form) '(0 1 2))
- (let ((count (nth 1 form)))
- (setq form (nth 2 form))
- (while (>= (setq count (1- count)) 0)
- (setq form (list 'cdr form)))
- form)
- (byte-optimize-predicate form))
- form))
- ;; Fixme: delete-char -> delete-region (byte-coded)
- ;; optimize string-as-unibyte, string-as-multibyte, string-make-unibyte,
- ;; string-make-multibyte for constant args.
- (put 'set 'byte-optimizer 'byte-optimize-set)
- (defun byte-optimize-set (form)
- (let ((var (car-safe (cdr-safe form))))
- (cond
- ((and (eq (car-safe var) 'quote) (consp (cdr var)))
- `(setq ,(cadr var) ,@(cddr form)))
- ((and (eq (car-safe var) 'make-local-variable)
- (eq (car-safe (setq var (car-safe (cdr var)))) 'quote)
- (consp (cdr var)))
- `(progn ,(cadr form) (setq ,(cadr var) ,@(cddr form))))
- (t form))))
- ;; enumerating those functions which need not be called if the returned
- ;; value is not used. That is, something like
- ;; (progn (list (something-with-side-effects) (yow))
- ;; (foo))
- ;; may safely be turned into
- ;; (progn (progn (something-with-side-effects) (yow))
- ;; (foo))
- ;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo.
- ;; Some of these functions have the side effect of allocating memory
- ;; and it would be incorrect to replace two calls with one.
- ;; But we don't try to do those kinds of optimizations,
- ;; so it is safe to list such functions here.
- ;; Some of these functions return values that depend on environment
- ;; state, so that constant folding them would be wrong,
- ;; but we don't do constant folding based on this list.
- ;; However, at present the only optimization we normally do
- ;; is delete calls that need not occur, and we only do that
- ;; with the error-free functions.
- ;; I wonder if I missed any :-\)
- (let ((side-effect-free-fns
- '(% * + - / /= 1+ 1- < <= = > >= abs acos append aref ash asin atan
- assoc assq
- boundp buffer-file-name buffer-local-variables buffer-modified-p
- buffer-substring byte-code-function-p
- capitalize car-less-than-car car cdr ceiling char-after char-before
- char-equal char-to-string char-width compare-strings
- compare-window-configurations concat coordinates-in-window-p
- copy-alist copy-sequence copy-marker cos count-lines
- decode-char
- decode-time default-boundp default-value documentation downcase
- elt encode-char exp expt encode-time error-message-string
- fboundp fceiling featurep ffloor
- file-directory-p file-exists-p file-locked-p file-name-absolute-p
- file-newer-than-file-p file-readable-p file-symlink-p file-writable-p
- float float-time floor format format-time-string frame-first-window
- frame-root-window frame-selected-window
- frame-visible-p fround ftruncate
- get gethash get-buffer get-buffer-window getenv get-file-buffer
- hash-table-count
- int-to-string intern-soft
- keymap-parent
- length local-variable-if-set-p local-variable-p log log10 logand
- logb logior lognot logxor lsh langinfo
- make-list make-string make-symbol marker-buffer max member memq min
- minibuffer-selected-window minibuffer-window
- mod multibyte-char-to-unibyte next-window nth nthcdr number-to-string
- parse-colon-path plist-get plist-member
- prefix-numeric-value previous-window prin1-to-string propertize
- degrees-to-radians
- radians-to-degrees rassq rassoc read-from-string regexp-quote
- region-beginning region-end reverse round
- sin sqrt string string< string= string-equal string-lessp string-to-char
- string-to-int string-to-number substring
- sxhash sxhash-equal sxhash-eq sxhash-eql
- symbol-function symbol-name symbol-plist symbol-value string-make-unibyte
- string-make-multibyte string-as-multibyte string-as-unibyte
- string-to-multibyte
- tan truncate
- unibyte-char-to-multibyte upcase user-full-name
- user-login-name user-original-login-name custom-variable-p
- vconcat
- window-absolute-pixel-edges window-at window-body-height
- window-body-width window-buffer window-dedicated-p window-display-table
- window-combination-limit window-edges window-frame window-fringes
- window-height window-hscroll window-inside-edges
- window-inside-absolute-pixel-edges window-inside-pixel-edges
- window-left-child window-left-column window-margins window-minibuffer-p
- window-next-buffers window-next-sibling window-new-normal
- window-new-total window-normal-size window-parameter window-parameters
- window-parent window-pixel-edges window-point window-prev-buffers
- window-prev-sibling window-redisplay-end-trigger window-scroll-bars
- window-start window-text-height window-top-child window-top-line
- window-total-height window-total-width window-use-time window-vscroll
- window-width zerop))
- (side-effect-and-error-free-fns
- '(arrayp atom
- bobp bolp bool-vector-p
- buffer-end buffer-list buffer-size buffer-string bufferp
- car-safe case-table-p cdr-safe char-or-string-p characterp
- charsetp commandp cons consp
- current-buffer current-global-map current-indentation
- current-local-map current-minor-mode-maps current-time
- current-time-string current-time-zone
- eobp eolp eq equal eventp
- floatp following-char framep
- get-largest-window get-lru-window
- hash-table-p
- identity ignore integerp integer-or-marker-p interactive-p
- invocation-directory invocation-name
- keymapp keywordp
- line-beginning-position line-end-position list listp
- make-marker mark mark-marker markerp max-char
- memory-limit minibuffer-window
- mouse-movement-p
- natnump nlistp not null number-or-marker-p numberp
- one-window-p overlayp
- point point-marker point-min point-max preceding-char primary-charset
- processp
- recent-keys recursion-depth
- safe-length selected-frame selected-window sequencep
- standard-case-table standard-syntax-table stringp subrp symbolp
- syntax-table syntax-table-p
- this-command-keys this-command-keys-vector this-single-command-keys
- this-single-command-raw-keys
- user-real-login-name user-real-uid user-uid
- vector vectorp visible-frame-list
- wholenump window-configuration-p window-live-p
- window-valid-p windowp)))
- (while side-effect-free-fns
- (put (car side-effect-free-fns) 'side-effect-free t)
- (setq side-effect-free-fns (cdr side-effect-free-fns)))
- (while side-effect-and-error-free-fns
- (put (car side-effect-and-error-free-fns) 'side-effect-free 'error-free)
- (setq side-effect-and-error-free-fns (cdr side-effect-and-error-free-fns)))
- nil)
- ;; pure functions are side-effect free functions whose values depend
- ;; only on their arguments. For these functions, calls with constant
- ;; arguments can be evaluated at compile time. This may shift run time
- ;; errors to compile time.
- (let ((pure-fns
- '(concat symbol-name regexp-opt regexp-quote string-to-syntax)))
- (while pure-fns
- (put (car pure-fns) 'pure t)
- (setq pure-fns (cdr pure-fns)))
- nil)
- (defconst byte-constref-ops
- '(byte-constant byte-constant2 byte-varref byte-varset byte-varbind))
- ;; Used and set dynamically in byte-decompile-bytecode-1.
- (defvar bytedecomp-op)
- (defvar bytedecomp-ptr)
- ;; This function extracts the bitfields from variable-length opcodes.
- ;; Originally defined in disass.el (which no longer uses it.)
- (defun disassemble-offset (bytes)
- "Don't call this!"
- ;; Fetch and return the offset for the current opcode.
- ;; Return nil if this opcode has no offset.
- (cond ((< bytedecomp-op byte-pophandler)
- (let ((tem (logand bytedecomp-op 7)))
- (setq bytedecomp-op (logand bytedecomp-op 248))
- (cond ((eq tem 6)
- ;; Offset in next byte.
- (setq bytedecomp-ptr (1+ bytedecomp-ptr))
- (aref bytes bytedecomp-ptr))
- ((eq tem 7)
- ;; Offset in next 2 bytes.
- (setq bytedecomp-ptr (1+ bytedecomp-ptr))
- (+ (aref bytes bytedecomp-ptr)
- (progn (setq bytedecomp-ptr (1+ bytedecomp-ptr))
- (lsh (aref bytes bytedecomp-ptr) 8))))
- (t tem)))) ;Offset was in opcode.
- ((>= bytedecomp-op byte-constant)
- (prog1 (- bytedecomp-op byte-constant) ;Offset in opcode.
- (setq bytedecomp-op byte-constant)))
- ((or (and (>= bytedecomp-op byte-constant2)
- (<= bytedecomp-op byte-goto-if-not-nil-else-pop))
- (memq bytedecomp-op (eval-when-compile
- (list byte-stack-set2 byte-pushcatch
- byte-pushconditioncase))))
- ;; Offset in next 2 bytes.
- (setq bytedecomp-ptr (1+ bytedecomp-ptr))
- (+ (aref bytes bytedecomp-ptr)
- (progn (setq bytedecomp-ptr (1+ bytedecomp-ptr))
- (lsh (aref bytes bytedecomp-ptr) 8))))
- ((and (>= bytedecomp-op byte-listN)
- (<= bytedecomp-op byte-discardN))
- (setq bytedecomp-ptr (1+ bytedecomp-ptr)) ;Offset in next byte.
- (aref bytes bytedecomp-ptr))))
- (defvar byte-compile-tag-number)
- ;; This de-compiler is used for inline expansion of compiled functions,
- ;; and by the disassembler.
- ;;
- ;; This list contains numbers, which are pc values,
- ;; before each instruction.
- (defun byte-decompile-bytecode (bytes constvec)
- "Turn BYTECODE into lapcode, referring to CONSTVEC."
- (let ((byte-compile-constants nil)
- (byte-compile-variables nil)
- (byte-compile-tag-number 0))
- (byte-decompile-bytecode-1 bytes constvec)))
- ;; As byte-decompile-bytecode, but updates
- ;; byte-compile-{constants, variables, tag-number}.
- ;; If MAKE-SPLICEABLE is true, then `return' opcodes are replaced
- ;; with `goto's destined for the end of the code.
- ;; That is for use by the compiler.
- ;; If MAKE-SPLICEABLE is nil, we are being called for the disassembler.
- ;; In that case, we put a pc value into the list
- ;; before each insn (or its label).
- (defun byte-decompile-bytecode-1 (bytes constvec &optional make-spliceable)
- (let ((length (length bytes))
- (bytedecomp-ptr 0) optr tags bytedecomp-op offset
- lap tmp last-constant)
- (while (not (= bytedecomp-ptr length))
- (or make-spliceable
- (push bytedecomp-ptr lap))
- (setq bytedecomp-op (aref bytes bytedecomp-ptr)
- optr bytedecomp-ptr
- ;; This uses dynamic-scope magic.
- offset (disassemble-offset bytes))
- (let ((opcode (aref byte-code-vector bytedecomp-op)))
- (cl-assert opcode)
- (setq bytedecomp-op opcode))
- (cond ((memq bytedecomp-op byte-goto-ops)
- ;; It's a pc.
- (setq offset
- (cdr (or (assq offset tags)
- (let ((new (cons offset (byte-compile-make-tag))))
- (push new tags)
- new)))))
- ((cond ((eq bytedecomp-op 'byte-constant2)
- (setq bytedecomp-op 'byte-constant) t)
- ((memq bytedecomp-op byte-constref-ops)))
- (setq tmp (if (>= offset (length constvec))
- (list 'out-of-range offset)
- (aref constvec offset))
- offset (if (eq bytedecomp-op 'byte-constant)
- (byte-compile-get-constant tmp)
- (or (assq tmp byte-compile-variables)
- (let ((new (list tmp)))
- (push new byte-compile-variables)
- new)))
- last-constant tmp))
- ((eq bytedecomp-op 'byte-stack-set2)
- (setq bytedecomp-op 'byte-stack-set))
- ((and (eq bytedecomp-op 'byte-discardN) (>= offset #x80))
- ;; The top bit of the operand for byte-discardN is a flag,
- ;; saying whether the top-of-stack is preserved. In
- ;; lapcode, we represent this by using a different opcode
- ;; (with the flag removed from the operand).
- (setq bytedecomp-op 'byte-discardN-preserve-tos)
- (setq offset (- offset #x80)))
- ((eq bytedecomp-op 'byte-switch)
- (cl-assert (hash-table-p last-constant) nil
- "byte-switch used without preceeding hash table")
- ;; We cannot use the original hash table referenced in the op,
- ;; so we create a copy of it, and replace the addresses with
- ;; TAGs.
- (let ((orig-table last-constant))
- (cl-loop for e across constvec
- when (eq e last-constant)
- do (setq last-constant (copy-hash-table e))
- and return nil)
- ;; Replace all addresses with TAGs.
- (maphash #'(lambda (value tag)
- (let (newtag)
- (setq newtag (byte-compile-make-tag))
- (push (cons tag newtag) tags)
- (puthash value newtag last-constant)))
- last-constant)
- ;; Replace the hash table referenced in the lapcode with our
- ;; modified one.
- (cl-loop for el in-ref lap
- when (and (listp el) ;; make sure we're at the correct op
- (eq (nth 1 el) 'byte-constant)
- (eq (nth 2 el) orig-table))
- ;; Jump tables are never reused, so do this exactly
- ;; once.
- do (setf (nth 2 el) last-constant) and return nil))))
- ;; lap = ( [ (pc . (op . arg)) ]* )
- (push (cons optr (cons bytedecomp-op (or offset 0)))
- lap)
- (setq bytedecomp-ptr (1+ bytedecomp-ptr)))
- (let ((rest lap))
- (while rest
- (cond ((numberp (car rest)))
- ((setq tmp (assq (car (car rest)) tags))
- ;; This addr is jumped to.
- (setcdr rest (cons (cons nil (cdr tmp))
- (cdr rest)))
- (setq tags (delq tmp tags))
- (setq rest (cdr rest))))
- (setq rest (cdr rest))))
- (if tags (error "optimizer error: missed tags %s" tags))
- ;; Remove addrs, lap = ( [ (op . arg) | (TAG tagno) ]* )
- (mapcar (function (lambda (elt)
- (if (numberp elt)
- elt
- (cdr elt))))
- (nreverse lap))))
- ;;; peephole optimizer
- (defconst byte-tagref-ops (cons 'TAG byte-goto-ops))
- (defconst byte-conditional-ops
- '(byte-goto-if-nil byte-goto-if-not-nil byte-goto-if-nil-else-pop
- byte-goto-if-not-nil-else-pop))
- (defconst byte-after-unbind-ops
- '(byte-constant byte-dup
- byte-symbolp byte-consp byte-stringp byte-listp byte-numberp byte-integerp
- byte-eq byte-not
- byte-cons byte-list1 byte-list2 ; byte-list3 byte-list4
- byte-interactive-p)
- ;; How about other side-effect-free-ops? Is it safe to move an
- ;; error invocation (such as from nth) out of an unwind-protect?
- ;; No, it is not, because the unwind-protect forms can alter
- ;; the inside of the object to which nth would apply.
- ;; For the same reason, byte-equal was deleted from this list.
- "Byte-codes that can be moved past an unbind.")
- (defconst byte-compile-side-effect-and-error-free-ops
- '(byte-constant byte-dup byte-symbolp byte-consp byte-stringp byte-listp
- byte-integerp byte-numberp byte-eq byte-equal byte-not byte-car-safe
- byte-cdr-safe byte-cons byte-list1 byte-list2 byte-point byte-point-max
- byte-point-min byte-following-char byte-preceding-char
- byte-current-column byte-eolp byte-eobp byte-bolp byte-bobp
- byte-current-buffer byte-stack-ref))
- (defconst byte-compile-side-effect-free-ops
- (nconc
- '(byte-varref byte-nth byte-memq byte-car byte-cdr byte-length byte-aref
- byte-symbol-value byte-get byte-concat2 byte-concat3 byte-sub1 byte-add1
- byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate
- byte-plus byte-max byte-min byte-mult byte-char-after byte-char-syntax
- byte-buffer-substring byte-string= byte-string< byte-nthcdr byte-elt
- byte-member byte-assq byte-quo byte-rem)
- byte-compile-side-effect-and-error-free-ops))
- ;; This crock is because of the way DEFVAR_BOOL variables work.
- ;; Consider the code
- ;;
- ;; (defun foo (flag)
- ;; (let ((old-pop-ups pop-up-windows)
- ;; (pop-up-windows flag))
- ;; (cond ((not (eq pop-up-windows old-pop-ups))
- ;; (setq old-pop-ups pop-up-windows)
- ;; ...))))
- ;;
- ;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is
- ;; something else. But if we optimize
- ;;
- ;; varref flag
- ;; varbind pop-up-windows
- ;; varref pop-up-windows
- ;; not
- ;; to
- ;; varref flag
- ;; dup
- ;; varbind pop-up-windows
- ;; not
- ;;
- ;; we break the program, because it will appear that pop-up-windows and
- ;; old-pop-ups are not EQ when really they are. So we have to know what
- ;; the BOOL variables are, and not perform this optimization on them.
- ;; The variable `byte-boolean-vars' is now primitive and updated
- ;; automatically by DEFVAR_BOOL.
- (defun byte-optimize-lapcode (lap &optional _for-effect)
- "Simple peephole optimizer. LAP is both modified and returned.
- If FOR-EFFECT is non-nil, the return value is assumed to be of no importance."
- (let (lap0
- lap1
- lap2
- (keep-going 'first-time)
- (add-depth 0)
- rest tmp tmp2 tmp3
- (side-effect-free (if byte-compile-delete-errors
- byte-compile-side-effect-free-ops
- byte-compile-side-effect-and-error-free-ops)))
- (while keep-going
- (or (eq keep-going 'first-time)
- (byte-compile-log-lap " ---- next pass"))
- (setq rest lap
- keep-going nil)
- (while rest
- (setq lap0 (car rest)
- lap1 (nth 1 rest)
- lap2 (nth 2 rest))
- ;; You may notice that sequences like "dup varset discard" are
- ;; optimized but sequences like "dup varset TAG1: discard" are not.
- ;; You may be tempted to change this; resist that temptation.
- (cond ;;
- ;; <side-effect-free> pop --> <deleted>
- ;; ...including:
- ;; const-X pop --> <deleted>
- ;; varref-X pop --> <deleted>
- ;; dup pop --> <deleted>
- ;;
- ((and (eq 'byte-discard (car lap1))
- (memq (car lap0) side-effect-free))
- (setq keep-going t)
- (setq tmp (aref byte-stack+-info (symbol-value (car lap0))))
- (setq rest (cdr rest))
- (cond ((= tmp 1)
- (byte-compile-log-lap
- " %s discard\t-->\t<deleted>" lap0)
- (setq lap (delq lap0 (delq lap1 lap))))
- ((= tmp 0)
- (byte-compile-log-lap
- " %s discard\t-->\t<deleted> discard" lap0)
- (setq lap (delq lap0 lap)))
- ((= tmp -1)
- (byte-compile-log-lap
- " %s discard\t-->\tdiscard discard" lap0)
- (setcar lap0 'byte-discard)
- (setcdr lap0 0))
- ((error "Optimizer error: too much on the stack"))))
- ;;
- ;; goto*-X X: --> X:
- ;;
- ((and (memq (car lap0) byte-goto-ops)
- (eq (cdr lap0) lap1))
- (cond ((eq (car lap0) 'byte-goto)
- (setq lap (delq lap0 lap))
- (setq tmp "<deleted>"))
- ((memq (car lap0) byte-goto-always-pop-ops)
- (setcar lap0 (setq tmp 'byte-discard))
- (setcdr lap0 0))
- ((error "Depth conflict at tag %d" (nth 2 lap0))))
- (and (memq byte-optimize-log '(t byte))
- (byte-compile-log " (goto %s) %s:\t-->\t%s %s:"
- (nth 1 lap1) (nth 1 lap1)
- tmp (nth 1 lap1)))
- (setq keep-going t))
- ;;
- ;; varset-X varref-X --> dup varset-X
- ;; varbind-X varref-X --> dup varbind-X
- ;; const/dup varset-X varref-X --> const/dup varset-X const/dup
- ;; const/dup varbind-X varref-X --> const/dup varbind-X const/dup
- ;; The latter two can enable other optimizations.
- ;;
- ;; For lexical variables, we could do the same
- ;; stack-set-X+1 stack-ref-X --> dup stack-set-X+2
- ;; but this is a very minor gain, since dup is stack-ref-0,
- ;; i.e. it's only better if X>5, and even then it comes
- ;; at the cost of an extra stack slot. Let's not bother.
- ((and (eq 'byte-varref (car lap2))
- (eq (cdr lap1) (cdr lap2))
- (memq (car lap1) '(byte-varset byte-varbind)))
- (if (and (setq tmp (memq (car (cdr lap2)) byte-boolean-vars))
- (not (eq (car lap0) 'byte-constant)))
- nil
- (setq keep-going t)
- (if (memq (car lap0) '(byte-constant byte-dup))
- (progn
- (setq tmp (if (or (not tmp)
- (macroexp--const-symbol-p
- (car (cdr lap0))))
- (cdr lap0)
- (byte-compile-get-constant t)))
- (byte-compile-log-lap " %s %s %s\t-->\t%s %s %s"
- lap0 lap1 lap2 lap0 lap1
- (cons (car lap0) tmp))
- (setcar lap2 (car lap0))
- (setcdr lap2 tmp))
- (byte-compile-log-lap " %s %s\t-->\tdup %s" lap1 lap2 lap1)
- (setcar lap2 (car lap1))
- (setcar lap1 'byte-dup)
- (setcdr lap1 0)
- ;; The stack depth gets locally increased, so we will
- ;; increase maxdepth in case depth = maxdepth here.
- ;; This can cause the third argument to byte-code to
- ;; be larger than necessary.
- (setq add-depth 1))))
- ;;
- ;; dup varset-X discard --> varset-X
- ;; dup varbind-X discard --> varbind-X
- ;; dup stack-set-X discard --> stack-set-X-1
- ;; (the varbind variant can emerge from other optimizations)
- ;;
- ((and (eq 'byte-dup (car lap0))
- (eq 'byte-discard (car lap2))
- (memq (car lap1) '(byte-varset byte-varbind
- byte-stack-set)))
- (byte-compile-log-lap " dup %s discard\t-->\t%s" lap1 lap1)
- (setq keep-going t
- rest (cdr rest))
- (if (eq 'byte-stack-set (car lap1)) (cl-decf (cdr lap1)))
- (setq lap (delq lap0 (delq lap2 lap))))
- ;;
- ;; not goto-X-if-nil --> goto-X-if-non-nil
- ;; not goto-X-if-non-nil --> goto-X-if-nil
- ;;
- ;; it is wrong to do the same thing for the -else-pop variants.
- ;;
- ((and (eq 'byte-not (car lap0))
- (memq (car lap1) '(byte-goto-if-nil byte-goto-if-not-nil)))
- (byte-compile-log-lap " not %s\t-->\t%s"
- lap1
- (cons
- (if (eq (car lap1) 'byte-goto-if-nil)
- 'byte-goto-if-not-nil
- 'byte-goto-if-nil)
- (cdr lap1)))
- (setcar lap1 (if (eq (car lap1) 'byte-goto-if-nil)
- 'byte-goto-if-not-nil
- 'byte-goto-if-nil))
- (setq lap (delq lap0 lap))
- (setq keep-going t))
- ;;
- ;; goto-X-if-nil goto-Y X: --> goto-Y-if-non-nil X:
- ;; goto-X-if-non-nil goto-Y X: --> goto-Y-if-nil X:
- ;;
- ;; it is wrong to do the same thing for the -else-pop variants.
- ;;
- ((and (memq (car lap0)
- '(byte-goto-if-nil byte-goto-if-not-nil)) ; gotoX
- (eq 'byte-goto (car lap1)) ; gotoY
- (eq (cdr lap0) lap2)) ; TAG X
- (let ((inverse (if (eq 'byte-goto-if-nil (car lap0))
- 'byte-goto-if-not-nil 'byte-goto-if-nil)))
- (byte-compile-log-lap " %s %s %s:\t-->\t%s %s:"
- lap0 lap1 lap2
- (cons inverse (cdr lap1)) lap2)
- (setq lap (delq lap0 lap))
- (setcar lap1 inverse)
- (setq keep-going t)))
- ;;
- ;; const goto-if-* --> whatever
- ;;
- ((and (eq 'byte-constant (car lap0))
- (memq (car lap1) byte-conditional-ops)
- ;; If the `byte-constant's cdr is not a cons cell, it has
- ;; to be an index into the constant pool); even though
- ;; it'll be a constant, that constant is not known yet
- ;; (it's typically a free variable of a closure, so will
- ;; only be known when the closure will be built at
- ;; run-time).
- (consp (cdr lap0)))
- (cond ((if (memq (car lap1) '(byte-goto-if-nil
- byte-goto-if-nil-else-pop))
- (car (cdr lap0))
- (not (car (cdr lap0))))
- (byte-compile-log-lap " %s %s\t-->\t<deleted>"
- lap0 lap1)
- (setq rest (cdr rest)
- lap (delq lap0 (delq lap1 lap))))
- (t
- (byte-compile-log-lap " %s %s\t-->\t%s"
- lap0 lap1
- (cons 'byte-goto (cdr lap1)))
- (when (memq (car lap1) byte-goto-always-pop-ops)
- (setq lap (delq lap0 lap)))
- (setcar lap1 'byte-goto)))
- (setq keep-going t))
- ;;
- ;; varref-X varref-X --> varref-X dup
- ;; varref-X [dup ...] varref-X --> varref-X [dup ...] dup
- ;; stackref-X [dup ...] stackref-X+N --> stackref-X [dup ...] dup
- ;; We don't optimize the const-X variations on this here,
- ;; because that would inhibit some goto optimizations; we
- ;; optimize the const-X case after all other optimizations.
- ;;
- ((and (memq (car lap0) '(byte-varref byte-stack-ref))
- (progn
- (setq tmp (cdr rest))
- (setq tmp2 0)
- (while (eq (car (car tmp)) 'byte-dup)
- (setq tmp2 (1+ tmp2))
- (setq tmp (cdr tmp)))
- t)
- (eq (if (eq 'byte-stack-ref (car lap0))
- (+ tmp2 1 (cdr lap0))
- (cdr lap0))
- (cdr (car tmp)))
- (eq (car lap0) (car (car tmp))))
- (if (memq byte-optimize-log '(t byte))
- (let ((str ""))
- (setq tmp2 (cdr rest))
- (while (not (eq tmp tmp2))
- (setq tmp2 (cdr tmp2)
- str (concat str " dup")))
- (byte-compile-log-lap " %s%s %s\t-->\t%s%s dup"
- lap0 str lap0 lap0 str)))
- (setq keep-going t)
- (setcar (car tmp) 'byte-dup)
- (setcdr (car tmp) 0)
- (setq rest tmp))
- ;;
- ;; TAG1: TAG2: --> TAG1: <deleted>
- ;; (and other references to TAG2 are replaced with TAG1)
- ;;
- ((and (eq (car lap0) 'TAG)
- (eq (car lap1) 'TAG))
- (and (memq byte-optimize-log '(t byte))
- (byte-compile-log " adjacent tags %d and %d merged"
- (nth 1 lap1) (nth 1 lap0)))
- (setq tmp3 lap)
- (while (setq tmp2 (rassq lap0 tmp3))
- (setcdr tmp2 lap1)
- (setq tmp3 (cdr (memq tmp2 tmp3))))
- (setq lap (delq lap0 lap)
- keep-going t)
- ;; replace references to tag in jump tables, if any
- (dolist (table byte-compile-jump-tables)
- (catch 'break
- (maphash #'(lambda (value tag)
- (when (equal tag lap0)
- ;; each tag occurs only once in the jump table
- (puthash value lap1 table)
- (throw 'break nil)))
- table))))
- ;;
- ;; unused-TAG: --> <deleted>
- ;;
- ((and (eq 'TAG (car lap0))
- (not (rassq lap0 lap))
- ;; make sure this tag isn't used in a jump-table
- (cl-loop for table in byte-compile-jump-tables
- when (member lap0 (hash-table-values table))
- return nil finally return t))
- (and (memq byte-optimize-log '(t byte))
- (byte-compile-log " unused tag %d removed" (nth 1 lap0)))
- (setq lap (delq lap0 lap)
- keep-going t))
- ;;
- ;; goto ... --> goto <delete until TAG or end>
- ;; return ... --> return <delete until TAG or end>
- ;; (unless a jump-table is being used, where deleting may affect
- ;; other valid case bodies)
- ;;
- ((and (memq (car lap0) '(byte-goto byte-return))
- (not (memq (car lap1) '(TAG nil)))
- ;; FIXME: Instead of deferring simply when jump-tables are
- ;; being used, keep a list of tags used for switch tags and
- ;; use them instead (see `byte-compile-inline-lapcode').
- (not byte-compile-jump-tables))
- (setq tmp rest)
- (let ((i 0)
- (opt-p (memq byte-optimize-log '(t lap)))
- str deleted)
- (while (and (setq tmp (cdr tmp))
- (not (eq 'TAG (car (car tmp)))))
- (if opt-p (setq deleted (cons (car tmp) deleted)
- str (concat str " %s")
- i (1+ i))))
- (if opt-p
- (let ((tagstr
- (if (eq 'TAG (car (car tmp)))
- (format "%d:" (car (cdr (car tmp))))
- (or (car tmp) ""))))
- (if (< i 6)
- (apply 'byte-compile-log-lap-1
- (concat " %s" str
- " %s\t-->\t%s <deleted> %s")
- lap0
- (nconc (nreverse deleted)
- (list tagstr lap0 tagstr)))
- (byte-compile-log-lap
- " %s <%d unreachable op%s> %s\t-->\t%s <deleted> %s"
- lap0 i (if (= i 1) "" "s")
- tagstr lap0 tagstr))))
- (rplacd rest tmp))
- (setq keep-going t))
- ;;
- ;; <safe-op> unbind --> unbind <safe-op>
- ;; (this may enable other optimizations.)
- ;;
- ((and (eq 'byte-unbind (car lap1))
- (memq (car lap0) byte-after-unbind-ops))
- (byte-compile-log-lap " %s %s\t-->\t%s %s" lap0 lap1 lap1 lap0)
- (setcar rest lap1)
- (setcar (cdr rest) lap0)
- (setq keep-going t))
- ;;
- ;; varbind-X unbind-N --> discard unbind-(N-1)
- ;; save-excursion unbind-N --> unbind-(N-1)
- ;; save-restriction unbind-N --> unbind-(N-1)
- ;;
- ((and (eq 'byte-unbind (car lap1))
- (memq (car lap0) '(byte-varbind byte-save-excursion
- byte-save-restriction))
- (< 0 (cdr lap1)))
- (if (zerop (setcdr lap1 (1- (cdr lap1))))
- (delq lap1 rest))
- (if (eq (car lap0) 'byte-varbind)
- (setcar rest (cons 'byte-discard 0))
- (setq lap (delq lap0 lap)))
- (byte-compile-log-lap " %s %s\t-->\t%s %s"
- lap0 (cons (car lap1) (1+ (cdr lap1)))
- (if (eq (car lap0) 'byte-varbind)
- (car rest)
- (car (cdr rest)))
- (if (and (/= 0 (cdr lap1))
- (eq (car lap0) 'byte-varbind))
- (car (cdr rest))
- ""))
- (setq keep-going t))
- ;;
- ;; goto*-X ... X: goto-Y --> goto*-Y
- ;; goto-X ... X: return --> return
- ;;
- ((and (memq (car lap0) byte-goto-ops)
- (memq (car (setq tmp (nth 1 (memq (cdr lap0) lap))))
- '(byte-goto byte-return)))
- (cond ((and (not (eq tmp lap0))
- (or (eq (car lap0) 'byte-goto)
- (eq (car tmp) 'byte-goto)))
- (byte-compile-log-lap " %s [%s]\t-->\t%s"
- (car lap0) tmp tmp)
- (if (eq (car tmp) 'byte-return)
- (setcar lap0 'byte-return))
- (setcdr lap0 (cdr tmp))
- (setq keep-going t))))
- ;;
- ;; goto-*-else-pop X ... X: goto-if-* --> whatever
- ;; goto-*-else-pop X ... X: discard --> whatever
- ;;
- ((and (memq (car lap0) '(byte-goto-if-nil-else-pop
- byte-goto-if-not-nil-else-pop))
- (memq (car (car (setq tmp (cdr (memq (cdr lap0) lap)))))
- (eval-when-compile
- (cons 'byte-discard byte-conditional-ops)))
- (not (eq lap0 (car tmp))))
- (setq tmp2 (car tmp))
- (setq tmp3 (assq (car lap0) '((byte-goto-if-nil-else-pop
- byte-goto-if-nil)
- (byte-goto-if-not-nil-else-pop
- byte-goto-if-not-nil))))
- (if (memq (car tmp2) tmp3)
- (progn (setcar lap0 (car tmp2))
- (setcdr lap0 (cdr tmp2))
- (byte-compile-log-lap " %s-else-pop [%s]\t-->\t%s"
- (car lap0) tmp2 lap0))
- ;; Get rid of the -else-pop's and jump one step further.
- (or (eq 'TAG (car (nth 1 tmp)))
- (setcdr tmp (cons (byte-compile-make-tag)
- (cdr tmp))))
- (byte-compile-log-lap " %s [%s]\t-->\t%s <skip>"
- (car lap0) tmp2 (nth 1 tmp3))
- (setcar lap0 (nth 1 tmp3))
- (setcdr lap0 (nth 1 tmp)))
- (setq keep-going t))
- ;;
- ;; const goto-X ... X: goto-if-* --> whatever
- ;; const goto-X ... X: discard --> whatever
- ;;
- ((and (eq (car lap0) 'byte-constant)
- (eq (car lap1) 'byte-goto)
- (memq (car (car (setq tmp (cdr (memq (cdr lap1) lap)))))
- (eval-when-compile
- (cons 'byte-discard byte-conditional-ops)))
- (not (eq lap1 (car tmp))))
- (setq tmp2 (car tmp))
- (cond ((when (consp (cdr lap0))
- (memq (car tmp2)
- (if (null (car (cdr lap0)))
- '(byte-goto-if-nil byte-goto-if-nil-else-pop)
- '(byte-goto-if-not-nil
- byte-goto-if-not-nil-else-pop))))
- (byte-compile-log-lap " %s goto [%s]\t-->\t%s %s"
- lap0 tmp2 lap0 tmp2)
- (setcar lap1 (car tmp2))
- (setcdr lap1 (cdr tmp2))
- ;; Let next step fix the (const,goto-if*) sequence.
- (setq rest (cons nil rest))
- (setq keep-going t))
- ((or (consp (cdr lap0))
- (eq (car tmp2) 'byte-discard))
- ;; Jump one step further
- (byte-compile-log-lap
- " %s goto [%s]\t-->\t<deleted> goto <skip>"
- lap0 tmp2)
- (or (eq 'TAG (car (nth 1 tmp)))
- (setcdr tmp (cons (byte-compile-make-tag)
- (cdr tmp))))
- (setcdr lap1 (car (cdr tmp)))
- (setq lap (delq lap0 lap))
- (setq keep-going t))))
- ;;
- ;; X: varref-Y ... varset-Y goto-X -->
- ;; X: varref-Y Z: ... dup varset-Y goto-Z
- ;; (varset-X goto-BACK, BACK: varref-X --> copy the varref down.)
- ;; (This is so usual for while loops that it is worth handling).
- ;;
- ;; Here again, we could do it for stack-ref/stack-set, but
- ;; that's replacing a stack-ref-Y with a stack-ref-0, which
- ;; is a very minor improvement (if any), at the cost of
- ;; more stack use and more byte-code. Let's not do it.
- ;;
- ((and (eq (car lap1) 'byte-varset)
- (eq (car lap2) 'byte-goto)
- (not (memq (cdr lap2) rest)) ;Backwards jump
- (eq (car (car (setq tmp (cdr (memq (cdr lap2) lap)))))
- 'byte-varref)
- (eq (cdr (car tmp)) (cdr lap1))
- (not (memq (car (cdr lap1)) byte-boolean-vars)))
- ;;(byte-compile-log-lap " Pulled %s to end of loop" (car tmp))
- (let ((newtag (byte-compile-make-tag)))
- (byte-compile-log-lap
- " %s: %s ... %s %s\t-->\t%s: %s %s: ... %s %s %s"
- (nth 1 (cdr lap2)) (car tmp)
- lap1 lap2
- (nth 1 (cdr lap2)) (car tmp)
- (nth 1 newtag) 'byte-dup lap1
- (cons 'byte-goto newtag)
- )
- (setcdr rest (cons (cons 'byte-dup 0) (cdr rest)))
- (setcdr tmp (cons (setcdr lap2 newtag) (cdr tmp))))
- (setq add-depth 1)
- (setq keep-going t))
- ;;
- ;; goto-X Y: ... X: goto-if*-Y --> goto-if-not-*-X+1 Y:
- ;; (This can pull the loop test to the end of the loop)
- ;;
- ((and (eq (car lap0) 'byte-goto)
- (eq (car lap1) 'TAG)
- (eq lap1
- (cdr (car (setq tmp (cdr (memq (cdr lap0) lap))))))
- (memq (car (car tmp))
- '(byte-goto byte-goto-if-nil byte-goto-if-not-nil
- byte-goto-if-nil-else-pop)))
- ;; (byte-compile-log-lap " %s %s, %s %s --> moved conditional"
- ;; lap0 lap1 (cdr lap0) (car tmp))
- (let ((newtag (byte-compile-make-tag)))
- (byte-compile-log-lap
- "%s %s: ... %s: %s\t-->\t%s ... %s:"
- lap0 (nth 1 lap1) (nth 1 (cdr lap0)) (car tmp)
- (cons (cdr (assq (car (car tmp))
- '((byte-goto-if-nil . byte-goto-if-not-nil)
- (byte-goto-if-not-nil . byte-goto-if-nil)
- (byte-goto-if-nil-else-pop .
- byte-goto-if-not-nil-else-pop)
- (byte-goto-if-not-nil-else-pop .
- byte-goto-if-nil-else-pop))))
- newtag)
- (nth 1 newtag)
- )
- (setcdr tmp (cons (setcdr lap0 newtag) (cdr tmp)))
- (if (eq (car (car tmp)) 'byte-goto-if-nil-else-pop)
- ;; We can handle this case but not the -if-not-nil case,
- ;; because we won't know which non-nil constant to push.
- (setcdr rest (cons (cons 'byte-constant
- (byte-compile-get-constant nil))
- (cdr rest))))
- (setcar lap0 (nth 1 (memq (car (car tmp))
- '(byte-goto-if-nil-else-pop
- byte-goto-if-not-nil
- byte-goto-if-nil
- byte-goto-if-not-nil
- byte-goto byte-goto))))
- )
- (setq keep-going t))
- )
- (setq rest (cdr rest)))
- )
- ;; Cleanup stage:
- ;; Rebuild byte-compile-constants / byte-compile-variables.
- ;; Simple optimizations that would inhibit other optimizations if they
- ;; were done in the optimizing loop, and optimizations which there is no
- ;; need to do more than once.
- (setq byte-compile-constants nil
- byte-compile-variables nil)
- (setq rest lap)
- (byte-compile-log-lap " ---- final pass")
- (while rest
- (setq lap0 (car rest)
- lap1 (nth 1 rest))
- (if (memq (car lap0) byte-constref-ops)
- (if (memq (car lap0) '(byte-constant byte-constant2))
- (unless (memq (cdr lap0) byte-compile-constants)
- (setq byte-compile-constants (cons (cdr lap0)
- byte-compile-constants)))
- (unless (memq (cdr lap0) byte-compile-variables)
- (setq byte-compile-variables (cons (cdr lap0)
- byte-compile-variables)))))
- (cond (;;
- ;; const-C varset-X const-C --> const-C dup varset-X
- ;; const-C varbind-X const-C --> const-C dup varbind-X
- ;;
- (and (eq (car lap0) 'byte-constant)
- (eq (car (nth 2 rest)) 'byte-constant)
- (eq (cdr lap0) (cdr (nth 2 rest)))
- (memq (car lap1) '(byte-varbind byte-varset)))
- (byte-compile-log-lap " %s %s %s\t-->\t%s dup %s"
- lap0 lap1 lap0 lap0 lap1)
- (setcar (cdr (cdr rest)) (cons (car lap1) (cdr lap1)))
- (setcar (cdr rest) (cons 'byte-dup 0))
- (setq add-depth 1))
- ;;
- ;; const-X [dup/const-X ...] --> const-X [dup ...] dup
- ;; varref-X [dup/varref-X ...] --> varref-X [dup ...] dup
- ;;
- ((memq (car lap0) '(byte-constant byte-varref))
- (setq tmp rest
- tmp2 nil)
- (while (progn
- (while (eq 'byte-dup (car (car (setq tmp (cdr tmp))))))
- (and (eq (cdr lap0) (cdr (car tmp)))
- (eq (car lap0) (car (car tmp)))))
- (setcar tmp (cons 'byte-dup 0))
- (setq tmp2 t))
- (if tmp2
- (byte-compile-log-lap
- " %s [dup/%s]...\t-->\t%s dup..." lap0 lap0 lap0)))
- ;;
- ;; unbind-N unbind-M --> unbind-(N+M)
- ;;
- ((and (eq 'byte-unbind (car lap0))
- (eq 'byte-unbind (car lap1)))
- (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1
- (cons 'byte-unbind
- (+ (cdr lap0) (cdr lap1))))
- (setq lap (delq lap0 lap))
- (setcdr lap1 (+ (cdr lap1) (cdr lap0))))
- ;;
- ;; stack-set-M [discard/discardN ...] --> discardN-preserve-tos
- ;; stack-set-M [discard/discardN ...] --> discardN
- ;;
- ((and (eq (car lap0) 'byte-stack-set)
- (memq (car lap1) '(byte-discard byte-discardN))
- (progn
- ;; See if enough discard operations follow to expose or
- ;; destroy the value stored by the stack-set.
- (setq tmp (cdr rest))
- (setq tmp2 (1- (cdr lap0)))
- (setq tmp3 0)
- (while (memq (car (car tmp)) '(byte-discard byte-discardN))
- (setq tmp3
- (+ tmp3 (if (eq (car (car tmp)) 'byte-discard)
- 1
- (cdr (car tmp)))))
- (setq tmp (cdr tmp)))
- (>= tmp3 tmp2)))
- ;; Do the optimization.
- (setq lap (delq lap0 lap))
- (setcar lap1
- (if (= tmp2 tmp3)
- ;; The value stored is the new TOS, so pop one more
- ;; value (to get rid of the old value) using the
- ;; TOS-preserving discard operator.
- 'byte-discardN-preserve-tos
- ;; Otherwise, the value stored is lost, so just use a
- ;; normal discard.
- 'byte-discardN))
- (setcdr lap1 (1+ tmp3))
- (setcdr (cdr rest) tmp)
- (byte-compile-log-lap " %s [discard/discardN]...\t-->\t%s"
- lap0 lap1))
- ;;
- ;; discard/discardN/discardN-preserve-tos-X discard/discardN-Y -->
- ;; discardN-(X+Y)
- ;;
- ((and (memq (car lap0)
- '(byte-discard byte-discardN
- byte-discardN-preserve-tos))
- (memq (car lap1) '(byte-discard byte-discardN)))
- (setq lap (delq lap0 lap))
- (byte-compile-log-lap
- " %s %s\t-->\t(discardN %s)"
- lap0 lap1
- (+ (if (eq (car lap0) 'byte-discard) 1 (cdr lap0))
- (if (eq (car lap1) 'byte-discard) 1 (cdr lap1))))
- (setcdr lap1 (+ (if (eq (car lap0) 'byte-discard) 1 (cdr lap0))
- (if (eq (car lap1) 'byte-discard) 1 (cdr lap1))))
- (setcar lap1 'byte-discardN))
- ;;
- ;; discardN-preserve-tos-X discardN-preserve-tos-Y -->
- ;; discardN-preserve-tos-(X+Y)
- ;;
- ((and (eq (car lap0) 'byte-discardN-preserve-tos)
- (eq (car lap1) 'byte-discardN-preserve-tos))
- (setq lap (delq lap0 lap))
- (setcdr lap1 (+ (cdr lap0) (cdr lap1)))
- (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1 (car rest)))
- ;;
- ;; discardN-preserve-tos return --> return
- ;; dup return --> return
- ;; stack-set-N return --> return ; where N is TOS-1
- ;;
- ((and (eq (car lap1) 'byte-return)
- (or (memq (car lap0) '(byte-discardN-preserve-tos byte-dup))
- (and (eq (car lap0) 'byte-stack-set)
- (= (cdr lap0) 1))))
- ;; The byte-code interpreter will pop the stack for us, so
- ;; we can just leave stuff on it.
- (setq lap (delq lap0 lap))
- (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1 lap1))
- )
- (setq rest (cdr rest)))
- (setq byte-compile-maxdepth (+ byte-compile-maxdepth add-depth)))
- lap)
- (provide 'byte-opt)
- ;; To avoid "lisp nesting exceeds max-lisp-eval-depth" when this file compiles
- ;; itself, compile some of its most used recursive functions (at load time).
- ;;
- (eval-when-compile
- (or (byte-code-function-p (symbol-function 'byte-optimize-form))
- (assq 'byte-code (symbol-function 'byte-optimize-form))
- (let ((byte-optimize nil)
- (byte-compile-warnings nil))
- (mapc (lambda (x)
- (or noninteractive (message "compiling %s..." x))
- (byte-compile x)
- (or noninteractive (message "compiling %s...done" x)))
- '(byte-optimize-form
- byte-optimize-body
- byte-optimize-predicate
- byte-optimize-binary-predicate
- ;; Inserted some more than necessary, to speed it up.
- byte-optimize-form-code-walker
- byte-optimize-lapcode))))
- nil)
- ;;; byte-opt.el ends here
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