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diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el new file mode 100644 index 00000000000..b595d6699d9 --- /dev/null +++ b/lisp/emacs-lisp/byte-opt.el @@ -0,0 +1,1730 @@ +;;; -*- Mode:Emacs-Lisp -*- +;;; The optimization passes of the emacs-lisp byte compiler. + +;; By Jamie Zawinski <jwz@lucid.com> and Hallvard Furuseth <hbf@ulrik.uio.no>. +;; last modified 29-oct-91. + +;; 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 1, 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; see the file COPYING. If not, write to +;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + +;;; ======================================================================== +;;; "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)) +;;; +;;; collapse common subexpressions +;;; +;;; 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 'inhibit-quit 'binding-is-magic t) +;;; (put 'quit-flag '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. +;;; +;;; 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 elisp. 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 elisp functions that take any arguments or make any bindings. +;;; +;;; Here is an example of an elisp 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 elisp 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 defvarred +;;; 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.) +;;; +;;; Really the Right Thing is to make lexical scope the default across +;;; the board, in the interpreter and compiler, and just FIX all of +;;; the code that relies on dynamic scope of non-defvarred variables. + + +(require 'byte-compile "bytecomp") + +(or (fboundp 'byte-compile-lapcode) + (error "loading bytecomp got the wrong version of the compiler.")) + +(defun byte-compile-log-lap-1 (format &rest args) + (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 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) + (list 'and + '(memq byte-optimize-log '(t byte)) + (cons 'byte-compile-log-lap-1 + (cons 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 ((fn (car-safe sexp))) + (if (and (symbolp fn) + (or (cdr (assq fn byte-compile-function-environment)) + (and (fboundp fn) + (not (or (cdr (assq fn byte-compile-macro-environment)) + (and (consp (setq fn (symbol-function fn))) + (eq (car fn) 'macro)) + (subrp fn)))))) + (byte-compile-inline-expand sexp) + sexp))) + (cdr form)))) + + +(defun byte-inline-lapcode (lap) + "splice the given lap code into the current instruction stream. +If it has any labels in it, you're responsible for making sure there +are no collisions, and that byte-compile-tag-number is reasonable +after this is spliced in. the provided list is destroyed." + (setq byte-compile-output (nconc (nreverse lap) byte-compile-output))) + + +(defun byte-compile-inline-expand (form) + (let* ((name (car form)) + (fn (or (cdr (assq name byte-compile-function-environment)) + (and (fboundp name) (symbol-function name))))) + (if (null fn) + (progn + (byte-compile-warn "attempt to inline %s before it was defined" name) + form) + ;; else + (if (and (consp fn) (eq (car fn) 'autoload)) + (load (nth 1 fn))) + (if (and (consp fn) (eq (car fn) 'autoload)) + (error "file \"%s\" didn't define \"%s\"" (nth 1 fn) name)) + (if (symbolp fn) + (byte-compile-inline-expand (cons fn (cdr form))) + (if (compiled-function-p fn) + (cons (list 'lambda (aref fn 0) + (list 'byte-code (aref fn 1) (aref fn 2) (aref fn 3))) + (cdr form)) + (if (not (eq (car fn) 'lambda)) (error "%s is not a lambda" name)) + (cons fn (cdr form))))))) + +;;; ((lambda ...) ...) +;;; +(defun byte-compile-unfold-lambda (form &optional name) + (or name (setq name "anonymous lambda")) + (let ((lambda (car form)) + (values (cdr form))) + (if (compiled-function-p lambda) + (setq lambda (list 'lambda (nth 0 form) + (list 'byte-code + (nth 1 form) (nth 2 form) (nth 3 form))))) + (let ((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))) + (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) + (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)) + ((or (compiled-function-p fn) + (eq 'lambda (car-safe fn))) + (byte-compile-unfold-lambda 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)) + (progn + (setq tmp (byte-optimize-body (cdr form) for-effect)) + (if (cdr tmp) (cons 'progn tmp) (car tmp))) + (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)) + ;; 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) + (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 concievably 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 backwards)))) + (cons fn (mapcar 'byte-optimize-form (cdr form))))) + + ((eq fn 'interactive) + (byte-compile-warn "misplaced interactive spec: %s" + (prin1-to-string form)) + nil) + + ((memq fn '(defun defmacro function + condition-case save-window-excursion)) + ;; These forms are compiled as constants or by breaking out + ;; all the subexpressions and compiling them separately. + 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) + ;; the body of a catch is compiled (and thus optimized) as a + ;; top-level form, so don't do it here. The tag is never + ;; for-effect. The body should have the same for-effect status + ;; as the catch form itself, but that isn't handled properly yet. + (cons fn + (cons (byte-optimize-form (nth 1 form) nil) + (cdr (cdr form))))) + + ;; If optimization is on, this is the only place that macros are + ;; expanded. If optimization is off, then macroexpansion happens + ;; in byte-compile-form. Otherwise, the macros are already expanded + ;; by the time that is reached. + ((not (eq form + (setq form (macroexpand form + byte-compile-macro-environment)))) + (byte-optimize-form form for-effect)) + + ((not (symbolp fn)) + (or (eq 'mocklisp (car-safe fn)) ; ha! + (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 "%s called for effect" + (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. + (cons fn (mapcar 'byte-optimize-form (cdr form))))))) + + +(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 (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. + +;; I'd like this to be a defsubst, but let's not be self-referental... +(defmacro byte-compile-trueconstp (form) + ;; Returns non-nil if FORM is a non-nil constant. + (` (cond ((consp (, form)) (eq (car (, form)) 'quote)) + ((not (symbolp (, form)))) + ((eq (, form) t))))) + +(defun byte-optimize-associative-math (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 *." + (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))) + +(defun byte-optimize-nonassociative-math (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 nonassociative, like - or /." + (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-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))) + (while (cdr (setq rest (cdr rest))) + (if (numberp (car rest)) + (let (constants) + (setq form (copy-sequence form) + rest (nthcdr (1- start) form)) + (while (setq rest (cdr rest)) + (cond ((numberp (car rest)) + (setq constants (cons (car rest) constants)) + (setcar rest nil)))) + (setq form (nconc (delq nil form) + (list (apply fun (nreverse constants)))))))) + form)) + +(defun byte-optimize-plus (form) + (setq form (byte-optimize-delay-constants-math form 1 '+)) + (if (memq 0 form) (setq form (delq 0 (copy-sequence form)))) + ;;(setq form (byte-optimize-associative-two-args-math form)) + (cond ((null (cdr form)) + (condition-case () + (eval form) + (error form))) + ((null (cdr (cdr form))) (nth 1 form)) + (t form))) + +(defun byte-optimize-minus (form) + ;; Put constants at the end, except the last constant. + (setq form (byte-optimize-delay-constants-math form 2 '+)) + ;; Now only first and last element can be a number. + (let ((last (car (reverse (nthcdr 3 form))))) + (cond ((eq 0 last) + ;; (- x y ... 0) --> (- x y ...) + (setq form (copy-sequence form)) + (setcdr (cdr (cdr form)) (delq 0 (nthcdr 3 form)))) + ;; If form is (- CONST foo... CONST), merge first and last. + ((and (numberp (nth 1 form)) + (numberp last)) + (setq form (nconc (list '- (- (nth 1 form) last) (nth 2 form)) + (delq last (copy-sequence (nthcdr 3 form)))))))) + (if (eq (nth 2 form) 0) + (nth 1 form) ; (- x 0) --> x + (byte-optimize-predicate + (if (and (null (cdr (cdr (cdr form)))) + (eq (nth 1 form) 0)) ; (- 0 x) --> (- x) + (cons (car form) (cdr (cdr form))) + form)))) + +(defun byte-optimize-multiply (form) + (setq form (byte-optimize-delay-constants-math form 1 '*)) + ;; If there is a constant in FORM, it is now the last element. + (cond ((null (cdr form)) 1) + ((null (cdr (cdr form))) (nth 1 form)) + ((let ((last (car (reverse form)))) + (cond ((eq 0 last) (list 'progn (cdr form))) + ((eq 1 last) (delq 1 (copy-sequence form))) + ((eq -1 last) (list '- (delq -1 (copy-sequence form)))) + ((and (eq 2 last) + (memq t (mapcar 'symbolp (cdr form)))) + (prog1 (setq form (delq 2 (copy-sequence form))) + (while (not (symbolp (car (setq form (cdr form)))))) + (setcar form (list '+ (car form) (car form))))) + (form)))))) + +(defsubst byte-compile-butlast (form) + (nreverse (cdr (reverse form)))) + +(defun byte-optimize-divide (form) + (setq form (byte-optimize-delay-constants-math form 2 '*)) + (let ((last (car (reverse (cdr (cdr form)))))) + (if (numberp last) + (cond ((= last 1) + (setq form (byte-compile-butlast form))) + ((numberp (nth 1 form)) + (setq form (cons (car form) + (cons (/ (nth 1 form) last) + (byte-compile-butlast (cdr (cdr form))))) + last nil)))) + (cond ((null (cdr (cdr form))) + (nth 1 form)) + ((eq (nth 1 form) 0) + (append '(progn) (cdr (cdr form)) '(0))) + ((eq last -1) + (list '- (if (nthcdr 3 form) + (byte-compile-butlast form) + (nth 1 form)))) + (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)) + (delq -1 (copy-sequence form))) + (form)))) + + +(defun byte-optimize-binary-predicate (form) + (if (byte-compile-constp (nth 1 form)) + (if (byte-compile-constp (nth 2 form)) + (condition-case () + (list 'quote (eval form)) + (error form)) + ;; This can enable some lapcode optimizations. + (list (car form) (nth 2 form) (nth 1 form))) + form)) + +(defun byte-optimize-predicate (form) + (let ((ok t) + (rest (cdr form))) + (while (and rest ok) + (setq ok (byte-compile-constp (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 'eql '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 numerinc 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 (memq (nth 1 form) '(nil t))))) + form + (nth 1 form))) + +(defun byte-optimize-zerop (form) + (cond ((numberp (nth 1 form)) + (eval form)) + (byte-compile-delete-errors + (list '= (nth 1 form) 0)) + (form))) + +(put 'zerop 'byte-optimizer 'byte-optimize-zerop) + +(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))) + (cond ((eq rest (cdr form)) + (setq form + (if (cdr (car rest)) + (if (cdr (cdr (car rest))) + (cons 'progn (cdr (car rest))) + (nth 1 (car rest))) + (car (car rest))))) + ((cdr rest) + (setq form (copy-sequence form)) + (setcdr (memq (car rest) form) nil))) + (setq 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 <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 ((byte-compile-trueconstp clause) + (nth 2 form)) + ((null clause) + (if (nthcdr 4 form) + (cons 'progn (nthcdr 3 form)) + (nth 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 (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) + (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 (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 (mapcar 'cdr (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 (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))) + +(put 'nthcdr 'byte-optimizer 'byte-optimize-nthcdr) +(defun byte-optimize-nthcdr (form) + (let ((count (nth 1 form))) + (if (not (memq count '(0 1 2))) + (byte-optimize-predicate form) + (setq form (nth 2 form)) + (while (natnump (setq count (1- count))) + (setq form (list 'cdr form))) + 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. + +;;; I wonder if I missed any :-\) +(let ((side-effect-free-fns + '(% * + / /= 1+ < <= = > >= append aref ash assoc assq boundp + buffer-file-name buffer-local-variables buffer-modified-p + buffer-substring capitalize car cdr concat coordinates-in-window-p + copy-marker count-lines documentation downcase elt fboundp featurep + 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 + format get get-buffer get-buffer-window getenv get-file-buffer length + logand logior lognot logxor lsh marker-buffer max member memq min mod + next-window nth nthcdr previous-window rassq regexp-quote reverse + string< string= string-lessp string-equal substring user-variable-p + window-buffer window-edges window-height window-hscroll window-width + zerop)) + ;; could also add plusp, minusp, signum. If anyone ever defines + ;; these, they will certainly be side-effect free. + (side-effect-and-error-free-fns + '(arrayp atom bobp bolp buffer-end buffer-list buffer-size + buffer-string bufferp char-or-string-p commandp cons consp + current-buffer dot dot-marker eobp eolp eq eql equal + get-largest-window identity integerp integer-or-marker-p + interactive-p keymapp list listp make-marker mark mark-marker + markerp minibuffer-window natnump nlistp not null numberp + one-window-p point point-marker processp selected-window sequencep + stringp subrp symbolp syntax-table-p vector vectorp 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) + + +(defun byte-compile-splice-in-already-compiled-code (form) + ;; form is (byte-code "..." [...] n) + (if (not (memq byte-optimize '(t lap))) + (byte-compile-normal-call form) + (byte-inline-lapcode + (byte-decompile-bytecode-1 (nth 1 form) (nth 2 form) t)) + (setq byte-compile-maxdepth (max (+ byte-compile-depth (nth 3 form)) + byte-compile-maxdepth)) + (setq byte-compile-depth (1+ byte-compile-depth)))) + +(put 'byte-code 'byte-compile 'byte-compile-splice-in-already-compiled-code) + + +(defconst byte-constref-ops + '(byte-constant byte-constant2 byte-varref byte-varset byte-varbind)) + +;;; This function extracts the bitfields from variable-length opcodes. +;;; Originally defined in disass.el (which no longer uses it.) + +(defun disassemble-offset () + "Don't call this!" + ;; fetch and return the offset for the current opcode. + ;; return NIL if this opcode has no offset + ;; OP, PTR and BYTES are used and set dynamically + (defvar op) + (defvar ptr) + (defvar bytes) + (cond ((< op byte-nth) + (let ((tem (logand op 7))) + (setq op (logand op 248)) + (cond ((eq tem 6) + (setq ptr (1+ ptr)) ;offset in next byte + (aref bytes ptr)) + ((eq tem 7) + (setq ptr (1+ ptr)) ;offset in next 2 bytes + (+ (aref bytes ptr) + (progn (setq ptr (1+ ptr)) + (lsh (aref bytes ptr) 8)))) + (t tem)))) ;offset was in opcode + ((>= op byte-constant) + (prog1 (- op byte-constant) ;offset in opcode + (setq op byte-constant))) + ((and (>= op byte-constant2) + (<= op byte-goto-if-not-nil-else-pop)) + (setq ptr (1+ ptr)) ;offset in next 2 bytes + (+ (aref bytes ptr) + (progn (setq ptr (1+ ptr)) + (lsh (aref bytes ptr) 8)))) + ((and (>= op byte-rel-goto) + (<= op byte-insertN)) + (setq ptr (1+ ptr)) ;offset in next byte + (aref bytes ptr)))) + + +;;; This de-compiler is used for inline expansion of compiled functions, +;;; and by the disassembler. +;;; +(defun byte-decompile-bytecode (bytes constvec) + "Turns BYTECODE into lapcode, refering to CONSTVEC." + (let ((byte-compile-constants nil) + (byte-compile-variables nil) + (byte-compile-tag-number 0)) + (byte-decompile-bytecode-1 bytes constvec))) + +(defun byte-decompile-bytecode-1 (bytes constvec &optional make-splicable) + "As byte-decompile-bytecode, but updates +byte-compile-{constants, variables, tag-number}. +If the optional 3rd arg is true, then `return' opcodes are replaced +with `goto's destined for the end of the code." + (let ((length (length bytes)) + (ptr 0) optr tag tags op offset + lap tmp + endtag + (retcount 0)) + (while (not (= ptr length)) + (setq op (aref bytes ptr) + optr ptr + offset (disassemble-offset)) ; this does dynamic-scope magic + (setq op (aref byte-code-vector op)) + (cond ((or (memq op byte-goto-ops) + (cond ((memq op byte-rel-goto-ops) + (setq op (aref byte-code-vector + (- (symbol-value op) + (- byte-rel-goto byte-goto)))) + (setq offset (+ ptr (- offset 127))) + t))) + ;; it's a pc + (setq offset + (cdr (or (assq offset tags) + (car (setq tags + (cons (cons offset + (byte-compile-make-tag)) + tags))))))) + ((cond ((eq op 'byte-constant2) (setq op 'byte-constant) t) + ((memq op byte-constref-ops))) + (setq tmp (aref constvec offset) + offset (if (eq op 'byte-constant) + (byte-compile-get-constant tmp) + (or (assq tmp byte-compile-variables) + (car (setq byte-compile-variables + (cons (list tmp) + byte-compile-variables))))))) + ((and make-splicable + (eq op 'byte-return)) + (if (= ptr (1- length)) + (setq op nil) + (setq offset (or endtag (setq endtag (byte-compile-make-tag))) + op 'byte-goto)))) + ;; lap = ( [ (pc . (op . arg)) ]* ) + (setq lap (cons (cons optr (cons op (or offset 0))) + lap)) + (setq ptr (1+ ptr))) + ;; take off the dummy nil op that we replaced a trailing "return" with. + (let ((rest lap)) + (while rest + (cond ((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)) + (if (null (car (cdr (car lap)))) + (setq lap (cdr lap))) + (if endtag + (setq lap (cons (cons nil endtag) lap))) + ;; remove addrs, lap = ( [ (op . arg) | (TAG tagno) ]* ) + (mapcar 'cdr (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-equal 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? + "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-interactive-p)) + +(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 piece of shit 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. +;;; +(defconst byte-boolean-vars + '(abbrevs-changed abbrev-all-caps inverse-video visible-bell + check-protected-fields no-redraw-on-reenter cursor-in-echo-area + noninteractive stack-trace-on-error debug-on-error debug-on-quit + debug-on-next-call insert-default-directory vms-stmlf-recfm + indent-tabs-mode meta-flag load-in-progress defining-kbd-macro + completion-auto-help completion-ignore-case enable-recursive-minibuffers + print-escape-newlines delete-exited-processes parse-sexp-ignore-comments + words-include-escapes pop-up-windows auto-new-screen + reset-terminal-on-clear truncate-partial-width-windows + mode-line-inverse-video) + "DEFVAR_BOOL variables. Giving these any non-nil value sets them to t. +If this does not enumerate all DEFVAR_BOOL variables, the byte-optimizer +may generate incorrect code.") + +(defun byte-optimize-lapcode (lap &optional for-effect) + "Simple peephole optimizer. LAP is both modified and returned." + (let (lap0 off0 + lap1 off1 + lap2 off2 + (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. + ;; + ((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) + (memq (car (cdr lap0)) '(nil t))) + (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 + ;; (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-compile-log-lap " dup %s discard\t-->\t%s" lap1 lap1) + (setq keep-going t + rest (cdr rest)) + (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)) + (or (eq 'byte-goto-if-nil (car lap1)) + (eq 'byte-goto-if-not-nil (car lap1)))) + (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 (or (eq 'byte-goto-if-nil (car lap0)) + (eq 'byte-goto-if-not-nil (car lap0))) ; 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)) + (cond ((if (or (eq (car lap1) 'byte-goto-if-nil) + (eq (car lap1) '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 + (if (memq (car lap1) byte-goto-always-pop-ops) + (progn + (byte-compile-log-lap " %s %s\t-->\t%s" + lap0 lap1 (cons 'byte-goto (cdr lap1))) + (setq lap (delq lap0 lap))) + (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1 + (cons 'byte-goto (cdr lap1)))) + (setcar lap1 'byte-goto))) + (setq keep-going t)) + ;; + ;; varref-X varref-X --> varref-X dup + ;; varref-X [dup ...] varref-X --> varref-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 (eq 'byte-varref (car lap0)) + (progn + (setq tmp (cdr rest)) + (while (eq (car (car tmp)) 'byte-dup) + (setq tmp (cdr tmp))) + t) + (eq (cdr lap0) (cdr (car tmp))) + (eq 'byte-varref (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 " adjascent 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)) + ;; + ;; unused-TAG: --> <deleted> + ;; + ((and (eq 'TAG (car lap0)) + (not (rassq lap0 lap))) + (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> + ;; + ((and (memq (car lap0) '(byte-goto byte-return)) + (not (memq (car lap1) '(TAG nil)))) + (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:" (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 ((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))) + (t + ;; 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). + ;; + ((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) + (while rest + (setq lap0 (car rest) + lap1 (nth 1 rest)) + (if (memq (car lap0) byte-constref-ops) + (if (eq (cdr lap0) 'byte-constant) + (or (memq (cdr lap0) byte-compile-variables) + (setq byte-compile-variables (cons (cdr lap0) + byte-compile-variables))) + (or (memq (cdr lap0) byte-compile-constants) + (setq byte-compile-constants (cons (cdr lap0) + byte-compile-constants))))) + (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) (car (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]... %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 keep-going t) + (setq lap (delq lap0 lap)) + (setcdr lap1 (+ (cdr lap1) (cdr lap0)))) + ) + (setq rest (cdr rest))) + (setq byte-compile-maxdepth (+ byte-compile-maxdepth add-depth))) + lap) + +(provide 'byte-optimize) + + +;; 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 (compiled-function-p (symbol-function 'byte-optimize-form)) + (assq 'byte-code (symbol-function 'byte-optimize-form)) + (let ((byte-optimize nil) + (byte-compile-warnings nil)) + (mapcar '(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) |