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Diffstat (limited to 'lisp/emacs-lisp/byte-lexbind.el')
| -rw-r--r-- | lisp/emacs-lisp/byte-lexbind.el | 699 |
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diff --git a/lisp/emacs-lisp/byte-lexbind.el b/lisp/emacs-lisp/byte-lexbind.el deleted file mode 100644 index 06353e2eea..0000000000 --- a/lisp/emacs-lisp/byte-lexbind.el +++ /dev/null @@ -1,699 +0,0 @@ -;;; byte-lexbind.el --- Lexical binding support for byte-compiler -;; -;; Copyright (C) 2001, 2002, 2010, 2011 Free Software Foundation, Inc. -;; -;; Author: Miles Bader <[email protected]> -;; Keywords: lisp, compiler, lexical binding - -;; 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, 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, Inc., 59 Temple Place - Suite 330, -;; Boston, MA 02111-1307, USA. - -;;; Commentary: -;; - -;;; Code: - -(require 'bytecomp-preload "bytecomp") - -;; Downward closures aren't implemented yet, so this should always be nil -(defconst byte-compile-use-downward-closures nil - "If true, use `downward closures', which are closures that don't cons.") - -(defconst byte-compile-save-window-excursion-uses-eval t - "If true, the bytecode for `save-window-excursion' uses eval. -This means that the body of the form must be put into a closure.") - -(defun byte-compile-arglist-vars (arglist) - "Return a list of the variables in the lambda argument list ARGLIST." - (remq '&rest (remq '&optional arglist))) - - -;;; Variable extent analysis. - -;; A `lforminfo' holds information about lexical bindings in a form, and some -;; other info for analysis. It is a cons-cell, where the car is a list of -;; `lvarinfo' stuctures, which form an alist indexed by variable name, and the -;; cdr is the number of closures found in the form: -;; -;; LFORMINFO : ((LVARINFO ...) . NUM-CLOSURES)" -;; -;; A `lvarinfo' holds information about a single lexical variable. It is a -;; list whose car is the variable name (so an lvarinfo is suitable as an alist -;; entry), and the rest of the of which holds information about the variable: -;; -;; LVARINFO : (VAR NUM-REFS NUM-SETS CLOSED-OVER) -;; -;; NUM-REFS is the number of times the variable's value is used -;; NUM-SETS is the number of times the variable's value is set -;; CLOSED-OVER is non-nil if the variable is referenced -;; anywhere but in its original function-level" - -;;; lvarinfo: - -;; constructor -(defsubst byte-compile-make-lvarinfo (var &optional already-set) - (list var 0 (if already-set 1 0) 0 nil)) -;; accessors -(defsubst byte-compile-lvarinfo-var (vinfo) (car vinfo)) -(defsubst byte-compile-lvarinfo-num-refs (vinfo) (cadr vinfo)) -(defsubst byte-compile-lvarinfo-num-sets (vinfo) (nth 3 vinfo)) -(defsubst byte-compile-lvarinfo-closed-over-p (vinfo) (nth 4 vinfo)) -;; setters -(defsubst byte-compile-lvarinfo-note-ref (vinfo) - (setcar (cdr vinfo) (1+ (cadr vinfo)))) -(defsubst byte-compile-lvarinfo-note-set (vinfo) - (setcar (cddr vinfo) (1+ (nth 3 vinfo)))) -(defsubst byte-compile-lvarinfo-note-closure (vinfo) - (setcar (nthcdr 4 vinfo) t)) - -;;; lforminfo: - -;; constructor -(defsubst byte-compile-make-lforminfo () - (cons nil 0)) -;; accessors -(defalias 'byte-compile-lforminfo-vars 'car) -(defalias 'byte-compile-lforminfo-num-closures 'cdr) -;; setters -(defsubst byte-compile-lforminfo-add-var (finfo var &optional already-set) - (setcar finfo (cons (byte-compile-make-lvarinfo var already-set) - (car finfo)))) - -(defun byte-compile-lforminfo-make-closure-flag () - "Return a new `closure-flag'." - (cons nil nil)) - -(defsubst byte-compile-lforminfo-note-closure (lforminfo lvarinfo closure-flag) - "If a variable reference or definition is inside a closure, record that fact. -LFORMINFO describes the form currently being analyzed, and LVARINFO -describes the variable. CLOSURE-FLAG is either nil, if currently _not_ -inside a closure, and otherwise a `closure flag' returned by -`byte-compile-lforminfo-make-closure-flag'." - (when closure-flag - (byte-compile-lvarinfo-note-closure lvarinfo) - (unless (car closure-flag) - (setcdr lforminfo (1+ (cdr lforminfo))) - (setcar closure-flag t)))) - -(defun byte-compile-compute-lforminfo (form &optional special) - "Return information about variables lexically bound by FORM. -SPECIAL is a list of variables that are special, and so shouldn't be -bound lexically (in addition to variable that are considered special -because they are declared with `defvar', et al). - -The result is an `lforminfo' data structure." - (and - (consp form) - (let ((lforminfo (byte-compile-make-lforminfo))) - (cond ((eq (car form) 'let) - ;; Find the bound variables - (dolist (clause (cadr form)) - (let ((var (if (consp clause) (car clause) clause))) - (unless (or (special-variable-p var) (memq var special)) - (byte-compile-lforminfo-add-var lforminfo var t)))) - ;; Analyze the body - (unless (null (byte-compile-lforminfo-vars lforminfo)) - (byte-compile-lforminfo-analyze-forms lforminfo form 2 - special nil))) - ((eq (car form) 'let*) - (dolist (clause (cadr form)) - (let ((var (if (consp clause) (car clause) clause))) - ;; Analyze each initializer based on the previously - ;; bound variables. - (when (and (consp clause) lforminfo) - (byte-compile-lforminfo-analyze lforminfo (cadr clause) - special nil)) - (unless (or (special-variable-p var) (memq var special)) - (byte-compile-lforminfo-add-var lforminfo var t)))) - ;; Analyze the body - (unless (null (byte-compile-lforminfo-vars lforminfo)) - (byte-compile-lforminfo-analyze-forms lforminfo form 2 - special nil))) - ((eq (car form) 'condition-case) - ;; `condition-case' currently must dynamically bind the - ;; error variable, so do nothing. - ) - ((memq (car form) '(defun defmacro)) - (byte-compile-lforminfo-from-lambda lforminfo (cdr form) special)) - ((eq (car form) 'lambda) - (byte-compile-lforminfo-from-lambda lforminfo form special)) - ((and (consp (car form)) (eq (caar form) 'lambda)) - ;; An embedded lambda, which is basically just a `let' - (byte-compile-lforminfo-from-lambda lforminfo (cdr form) special))) - (if (byte-compile-lforminfo-vars lforminfo) - lforminfo - nil)))) - -(defun byte-compile-lforminfo-from-lambda (lforminfo lambda special) - "Initialize LFORMINFO from the lambda expression LAMBDA. -SPECIAL is a list of variables to ignore. -The first element of LAMBDA is ignored; it need not actually be `lambda'." - ;; Add the arguments - (dolist (arg (byte-compile-arglist-vars (cadr lambda))) - (byte-compile-lforminfo-add-var lforminfo arg t)) - ;; Analyze the body - (unless (null (byte-compile-lforminfo-vars lforminfo)) - (byte-compile-lforminfo-analyze-forms lforminfo lambda 2 special nil))) - -(defun byte-compile-lforminfo-analyze (lforminfo form &optional ignore closure-flag) - "Update variable information in LFORMINFO by analyzing FORM. -IGNORE is a list of variables that shouldn't be analyzed (usually because -they're special, or because some inner binding shadows the version in -LFORMINFO). CLOSURE-FLAG should be either nil or a `closure flag' created -with `byte-compile-lforminfo-make-closure-flag'; the latter indicates that -FORM is inside a lambda expression that may close over some variable in -LFORMINFO." - (cond ((symbolp form) - ;; variable reference - (unless (member form ignore) - (let ((vinfo (assq form (byte-compile-lforminfo-vars lforminfo)))) - (when vinfo - (byte-compile-lvarinfo-note-ref vinfo) - (byte-compile-lforminfo-note-closure lforminfo vinfo - closure-flag))))) - ;; function call/special form - ((consp form) - (let ((fun (car form))) - (cond - ((eq fun 'setq) - (pop form) - (while form - (let ((var (pop form))) - (byte-compile-lforminfo-analyze lforminfo (pop form) - ignore closure-flag) - (unless (member var ignore) - (let ((vinfo - (assq var (byte-compile-lforminfo-vars lforminfo)))) - (when vinfo - (byte-compile-lvarinfo-note-set vinfo) - (byte-compile-lforminfo-note-closure lforminfo vinfo - closure-flag))))))) - ((and (eq fun 'catch) (not (eq :fun-body (nth 2 form)))) - ;; tag - (byte-compile-lforminfo-analyze lforminfo (cadr form) - ignore closure-flag) - ;; `catch' uses a closure for the body - (byte-compile-lforminfo-analyze-forms - lforminfo form 2 - ignore - (or closure-flag - (and (not byte-compile-use-downward-closures) - (byte-compile-lforminfo-make-closure-flag))))) - ((eq fun 'cond) - (byte-compile-lforminfo-analyze-clauses lforminfo (cdr form) 0 - ignore closure-flag)) - ((eq fun 'condition-case) - ;; `condition-case' separates its body/handlers into - ;; separate closures. - (unless (or (eq (nth 1 form) :fun-body) - closure-flag byte-compile-use-downward-closures) - ;; condition case is implemented by calling a function - (setq closure-flag (byte-compile-lforminfo-make-closure-flag))) - ;; value form - (byte-compile-lforminfo-analyze lforminfo (nth 2 form) - ignore closure-flag) - ;; the error variable is always bound dynamically (because - ;; of the implementation) - (when (cadr form) - (push (cadr form) ignore)) - ;; handlers - (byte-compile-lforminfo-analyze-clauses lforminfo - (nthcdr 2 form) 1 - ignore closure-flag)) - ((eq fun '(defvar defconst)) - (byte-compile-lforminfo-analyze lforminfo (nth 2 form) - ignore closure-flag)) - ((memq fun '(defun defmacro)) - (byte-compile-lforminfo-analyze-forms lforminfo form 3 - ignore closure-flag)) - ((eq fun 'function) - ;; Analyze an embedded lambda expression [note: we only recognize - ;; it within (function ...) as the (lambda ...) for is actually a - ;; macro returning (function (lambda ...))]. - (when (and (consp (cadr form)) (eq (car (cadr form)) 'lambda)) - ;; shadow bound variables - (setq ignore - (append (byte-compile-arglist-vars (cadr (cadr form))) - ignore)) - ;; analyze body of lambda - (byte-compile-lforminfo-analyze-forms - lforminfo (cadr form) 2 - ignore - (or closure-flag - (byte-compile-lforminfo-make-closure-flag))))) - ((eq fun 'let) - ;; analyze variable inits - (byte-compile-lforminfo-analyze-clauses lforminfo (cadr form) 1 - ignore closure-flag) - ;; shadow bound variables - (dolist (clause (cadr form)) - (push (if (symbolp clause) clause (car clause)) - ignore)) - ;; analyze body - (byte-compile-lforminfo-analyze-forms lforminfo form 2 - ignore closure-flag)) - ((eq fun 'let*) - (dolist (clause (cadr form)) - (if (symbolp clause) - ;; shadow bound (to nil) variable - (push clause ignore) - ;; analyze variable init - (byte-compile-lforminfo-analyze lforminfo (cadr clause) - ignore closure-flag) - ;; shadow bound variable - (push (car clause) ignore))) - ;; analyze body - (byte-compile-lforminfo-analyze-forms lforminfo form 2 - ignore closure-flag)) - ((eq fun 'quote) - ;; do nothing - ) - ((and (eq fun 'save-window-excursion) - (not (eq :fun-body (nth 1 form)))) - ;; `save-window-excursion' currently uses a funny implementation - ;; that requires its body forms be put into a closure (it should - ;; be fixed to work more like `save-excursion' etc., do). - (byte-compile-lforminfo-analyze-forms - lforminfo form 2 - ignore - (or closure-flag - (and byte-compile-save-window-excursion-uses-eval - (not byte-compile-use-downward-closures) - (byte-compile-lforminfo-make-closure-flag))))) - ((and (consp fun) (eq (car fun) 'lambda)) - ;; Embedded lambda. These are inlined by the compiler, so - ;; we don't treat them like a real closure, more like `let'. - ;; analyze inits - (byte-compile-lforminfo-analyze-forms lforminfo form 2 - ignore closure-flag) - - ;; shadow bound variables - (setq ignore (nconc (byte-compile-arglist-vars (cadr fun)) - ignore)) - ;; analyze body - (byte-compile-lforminfo-analyze-forms lforminfo fun 2 - ignore closure-flag)) - (t - ;; For everything else, we just expand each argument (for - ;; setq/setq-default this works alright because the - ;; variable names are symbols). - (byte-compile-lforminfo-analyze-forms lforminfo form 1 - ignore closure-flag))))))) - -(defun byte-compile-lforminfo-analyze-forms - (lforminfo forms skip ignore closure-flag) - "Update variable information in LFORMINFO by analyzing each form in FORMS. -The first SKIP elements of FORMS are skipped without analysis. IGNORE -is a list of variables that shouldn't be analyzed (usually because -they're special, or because some inner binding shadows the version in -LFORMINFO). CLOSURE-FLAG should be either nil or a `closure flag' created with -`byte-compile-lforminfo-make-closure-flag'; the latter indicates that FORM is -inside a lambda expression that may close over some variable in LFORMINFO." - (when skip - (setq forms (nthcdr skip forms))) - (while forms - (byte-compile-lforminfo-analyze lforminfo (pop forms) - ignore closure-flag))) - -(defun byte-compile-lforminfo-analyze-clauses - (lforminfo clauses skip ignore closure-flag) - "Update variable information in LFORMINFO by analyzing each clause in CLAUSES. -Each clause is a list of forms; any clause that's not a list is ignored. The -first SKIP elements of each clause are skipped without analysis. IGNORE is a -list of variables that shouldn't be analyzed (usually because they're special, -or because some inner binding shadows the version in LFORMINFO). -CLOSURE-FLAG should be either nil or a `closure flag' created with -`byte-compile-lforminfo-make-closure-flag'; the latter indicates that FORM is -inside a lambda expression that may close over some variable in LFORMINFO." - (while clauses - (let ((clause (pop clauses))) - (when (consp clause) - (byte-compile-lforminfo-analyze-forms lforminfo clause skip - ignore closure-flag))))) - - -;;; Lexical environments - -;; A lexical environment is an alist, where each element is of the form -;; (VAR . (OFFSET . ENV)) where VAR is either a symbol, for normal -;; variables, or an `heapenv' descriptor for references to heap environment -;; vectors. ENV is either an atom, meaning a `stack allocated' variable -;; (the particular atom serves to indicate the particular function context -;; on whose stack it's allocated), or an `heapenv' descriptor (see above), -;; meaning a variable allocated in a heap environment vector. For the -;; later case, an anonymous `variable' holding a pointer to the environment -;; vector may be located by recursively looking up ENV in the environment -;; as if it were a variable (so the entry for that `variable' will have a -;; non-symbol VAR). - -;; We call a lexical environment a `lexenv', and an entry in it a `lexvar'. - -;; constructor -(defsubst byte-compile-make-lexvar (name offset &optional env) - (cons name (cons offset env))) -;; accessors -(defsubst byte-compile-lexvar-name (lexvar) (car lexvar)) -(defsubst byte-compile-lexvar-offset (lexvar) (cadr lexvar)) -(defsubst byte-compile-lexvar-environment (lexvar) (cddr lexvar)) -(defsubst byte-compile-lexvar-variable-p (lexvar) (symbolp (car lexvar))) -(defsubst byte-compile-lexvar-environment-p (lexvar) - (not (symbolp (car lexvar)))) -(defsubst byte-compile-lexvar-on-stack-p (lexvar) - (atom (byte-compile-lexvar-environment lexvar))) -(defsubst byte-compile-lexvar-in-heap-p (lexvar) - (not (byte-compile-lexvar-on-stack-p lexvar))) - -(defun byte-compile-make-lambda-lexenv (form closed-over-lexenv) - "Return a new lexical environment for a lambda expression FORM. -CLOSED-OVER-LEXENV is the lexical environment in which FORM occurs. -The returned lexical environment contains two sets of variables: - * Variables that were in CLOSED-OVER-LEXENV and used by FORM - (all of these will be `heap' variables) - * Arguments to FORM (all of these will be `stack' variables)." - ;; See if this is a closure or not - (let ((closure nil) - (lforminfo (byte-compile-make-lforminfo)) - (args (byte-compile-arglist-vars (cadr form)))) - ;; Add variables from surrounding lexical environment to analysis set - (dolist (lexvar closed-over-lexenv) - (when (and (byte-compile-lexvar-in-heap-p lexvar) - (not (memq (car lexvar) args))) - ;; The variable is located in a heap-allocated environment - ;; vector, so FORM may use it. Add it to the set of variables - ;; that we'll search for in FORM. - (byte-compile-lforminfo-add-var lforminfo (car lexvar)))) - ;; See how FORM uses these potentially closed-over variables. - (byte-compile-lforminfo-analyze lforminfo form args) - (let ((lexenv nil)) - (dolist (vinfo (byte-compile-lforminfo-vars lforminfo)) - (when (> (byte-compile-lvarinfo-num-refs vinfo) 0) - ;; FORM uses VINFO's variable, so it must be a closure. - (setq closure t) - ;; Make sure that the environment in which the variable is - ;; located is accessible (since we only ever pass the - ;; innermost environment to closures, if it's in some other - ;; envionment, there must be path to it from the innermost - ;; one). - (unless (byte-compile-lexvar-in-heap-p vinfo) - ;; To access the variable from FORM, it must be in the heap. - (error - "Compiler error: lexical variable `%s' should be heap-allocated but is not" - (car vinfo))) - (let ((closed-over-lexvar (assq (car vinfo) closed-over-lexenv))) - (byte-compile-heapenv-ensure-access - byte-compile-current-heap-environment - (byte-compile-lexvar-environment closed-over-lexvar)) - ;; Put this variable in the new lexical environment - (push closed-over-lexvar lexenv)))) - ;; Fill in the initial stack contents - (let ((stackpos 0)) - (when closure - ;; Add the magic first argument that holds the environment pointer - (push (byte-compile-make-lexvar byte-compile-current-heap-environment - 0) - lexenv) - (setq stackpos (1+ stackpos))) - ;; Add entries for each argument - (dolist (arg args) - (push (byte-compile-make-lexvar arg stackpos) lexenv) - (setq stackpos (1+ stackpos))) - ;; Return the new lexical environment - lexenv)))) - -(defun byte-compile-closure-initial-lexenv-p (lexenv) - "Return non-nil if LEXENV is the initial lexical environment for a closure. -This only works correctly when passed a new lexical environment as -returned by `byte-compile-make-lambda-lexenv' (it works by checking to -see whether there are any heap-allocated lexical variables in LEXENV)." - (let ((closure nil)) - (while (and lexenv (not closure)) - (when (byte-compile-lexvar-environment-p (pop lexenv)) - (setq closure t))) - closure)) - - -;;; Heap environment vectors - -;; A `heap environment vector' is heap-allocated vector used to store -;; variable that can't be put onto the stack. -;; -;; They are represented in the compiler by a list of the form -;; -;; (SIZE SIZE-CONST-ID INIT-POSITION . ENVS) -;; -;; SIZE is the current size of the vector (which may be -;; incremented if another variable or environment-reference is added to -;; the end). SIZE-CONST-ID is an `unknown constant id' (as returned by -;; `byte-compile-push-unknown-constant') representing the constant used -;; in the vector initialization code, and INIT-POSITION is a position -;; in the byte-code output (as returned by `byte-compile-delay-out') -;; at which more initialization code can be added. -;; ENVS is a list of other environment vectors accessible form this one, -;; where each element is of the form (ENV . OFFSET). - -;; constructor -(defsubst byte-compile-make-heapenv (size-const-id init-position) - (list 0 size-const-id init-position)) -;; accessors -(defsubst byte-compile-heapenv-size (heapenv) (car heapenv)) -(defsubst byte-compile-heapenv-size-const-id (heapenv) (cadr heapenv)) -(defsubst byte-compile-heapenv-init-position (heapenv) (nth 2 heapenv)) -(defsubst byte-compile-heapenv-accessible-envs (heapenv) (nthcdr 3 heapenv)) - -(defun byte-compile-heapenv-add-slot (heapenv) - "Add a slot to the heap environment HEAPENV and return its offset." - (prog1 (car heapenv) (setcar heapenv (1+ (car heapenv))))) - -(defun byte-compile-heapenv-add-accessible-env (heapenv env offset) - "Add to HEAPENV's list of accessible environments, ENV at OFFSET." - (setcdr (nthcdr 2 heapenv) - (cons (cons env offset) - (byte-compile-heapenv-accessible-envs heapenv)))) - -(defun byte-compile-push-heapenv () - "Generate byte-code to push a new heap environment vector. -Sets `byte-compile-current-heap-environment' to the compiler descriptor -for the new heap environment. -Return a `lexvar' descriptor for the new heap environment." - (let ((env-stack-pos byte-compile-depth) - size-const-id init-position) - ;; Generate code to push the vector - (byte-compile-push-constant 'make-vector) - (setq size-const-id (byte-compile-push-unknown-constant)) - (byte-compile-push-constant nil) - (byte-compile-out 'byte-call 2) - (setq init-position (byte-compile-delay-out 3)) - ;; Now make a heap-environment for the compiler to use - (setq byte-compile-current-heap-environment - (byte-compile-make-heapenv size-const-id init-position)) - (byte-compile-make-lexvar byte-compile-current-heap-environment - env-stack-pos))) - -(defun byte-compile-heapenv-ensure-access (heapenv other-heapenv) - "Make sure that HEAPENV can be used to access OTHER-HEAPENV. -If not, then add a new slot to HEAPENV pointing to OTHER-HEAPENV." - (unless (memq heapenv (byte-compile-heapenv-accessible-envs heapenv)) - (let ((offset (byte-compile-heapenv-add-slot heapenv))) - (byte-compile-heapenv-add-accessible-env heapenv other-heapenv offset)))) - - -;;; Variable binding/unbinding - -(defun byte-compile-non-stack-bindings-p (clauses lforminfo) - "Return non-nil if any lexical bindings in CLAUSES are not stack-allocated. -LFORMINFO should be information about lexical variables being bound." - (let ((vars (byte-compile-lforminfo-vars lforminfo))) - (or (not (= (length clauses) (length vars))) - (progn - (while (and vars clauses) - (when (byte-compile-lvarinfo-closed-over-p (pop vars)) - (setq clauses nil))) - (not clauses))))) - -(defun byte-compile-let-clauses-trivial-init-p (clauses) - "Return true if let binding CLAUSES all have a `trivial' init value. -Trivial means either a constant value, or a simple variable initialization." - (or (null clauses) - (and (or (atom (car clauses)) - (atom (cadr (car clauses))) - (eq (car (cadr (car clauses))) 'quote)) - (byte-compile-let-clauses-trivial-init-p (cdr clauses))))) - -(defun byte-compile-rearrange-let-clauses (clauses lforminfo) - "Return CLAUSES rearranged so non-stack variables come last if possible. -Care is taken to only do so when it's clear that the meaning is the same. -LFORMINFO should be information about lexical variables being bound." - ;; We currently do a very simple job by only exchanging clauses when - ;; one has a constant init, or one has a variable init and the other - ;; doesn't have a function call init (because that could change the - ;; value of the variable). This could be more clever and actually - ;; attempt to analyze which variables could possible be changed, etc. - (let ((unchanged nil) - (lex-non-stack nil) - (dynamic nil)) - (while clauses - (let* ((clause (pop clauses)) - (var (if (consp clause) (car clause) clause)) - (init (and (consp clause) (cadr clause))) - (vinfo (assq var (byte-compile-lforminfo-vars lforminfo)))) - (cond - ((or (and vinfo - (not (byte-compile-lvarinfo-closed-over-p vinfo))) - (not - (or (eq init nil) (eq init t) - (and (atom init) (not (symbolp init))) - (and (consp init) (eq (car init) 'quote)) - (byte-compile-let-clauses-trivial-init-p clauses)))) - (push clause unchanged)) - (vinfo - (push clause lex-non-stack)) - (t - (push clause dynamic))))) - (nconc (nreverse unchanged) (nreverse lex-non-stack) (nreverse dynamic)))) - -(defun byte-compile-maybe-push-heap-environment (&optional lforminfo) - "Push a new heap environment if necessary. -LFORMINFO should be information about lexical variables being bound. -Return a lexical environment containing only the heap vector (or -nil if nothing was pushed). -Also, `byte-compile-current-heap-environment' and -`byte-compile-current-num-closures' are updated to reflect any change (so they -should probably be bound by the caller to ensure that the new values have the -proper scope)." - ;; We decide whether a new heap environment is required by seeing if - ;; the number of closures inside the form described by LFORMINFO is - ;; the same as the number inside the binding form that created the - ;; currently active heap environment. - (let ((nclosures - (and lforminfo (byte-compile-lforminfo-num-closures lforminfo)))) - (if (or (null lforminfo) - (zerop nclosures) - (= nclosures byte-compile-current-num-closures)) - ;; No need to push a heap environment. - nil - (error "Should have been handled by cconv") - ;; Have to push one. A heap environment is really just a vector, so - ;; we emit bytecodes to create a vector. However, the size is not - ;; fixed yet (the vector can grow if subforms use it to store - ;; values, and if `access points' to parent heap environments are - ;; added), so we use `byte-compile-push-unknown-constant' to push the - ;; vector size. - (setq byte-compile-current-num-closures nclosures) - (list (byte-compile-push-heapenv))))) - -(defun byte-compile-bind (var init-lexenv &optional lforminfo) - "Emit byte-codes to bind VAR and update `byte-compile-lexical-environment'. -INIT-LEXENV should be a lexical-environment alist describing the -positions of the init value that have been pushed on the stack, and -LFORMINFO should be information about lexical variables being bound. -Return non-nil if the TOS value was popped." - ;; The presence of lexical bindings mean that we may have to - ;; juggle things on the stack, either to move them to TOS for - ;; dynamic binding, or to put them in a non-stack environment - ;; vector. - (let ((vinfo (assq var (byte-compile-lforminfo-vars lforminfo)))) - (cond ((and (null vinfo) (eq var (caar init-lexenv))) - ;; VAR is dynamic and is on the top of the - ;; stack, so we can just bind it like usual - (byte-compile-dynamic-variable-bind var) - t) - ((null vinfo) - ;; VAR is dynamic, but we have to get its - ;; value out of the middle of the stack - (let ((stack-pos (cdr (assq var init-lexenv)))) - (byte-compile-stack-ref stack-pos) - (byte-compile-dynamic-variable-bind var) - ;; Now we have to store nil into its temporary - ;; stack position to avoid problems with GC - (byte-compile-push-constant nil) - (byte-compile-stack-set stack-pos)) - nil) - ((byte-compile-lvarinfo-closed-over-p vinfo) - ;; VAR is lexical, but needs to be in a - ;; heap-allocated environment. - (unless byte-compile-current-heap-environment - (error "No current heap-environment to allocate `%s' in!" var)) - (let ((init-stack-pos - ;; nil if the init value is on the top of the stack, - ;; otherwise the position of the init value on the stack. - (and (not (eq var (caar init-lexenv))) - (byte-compile-lexvar-offset (assq var init-lexenv)))) - (env-vec-pos - ;; Position of VAR in the environment vector - (byte-compile-lexvar-offset - (assq var byte-compile-lexical-environment))) - (env-vec-stack-pos - ;; Position of the the environment vector on the stack - ;; (the heap-environment must _always_ be available on - ;; the stack!) - (byte-compile-lexvar-offset - (assq byte-compile-current-heap-environment - byte-compile-lexical-environment)))) - (unless env-vec-stack-pos - (error "Couldn't find location of current heap environment!")) - (when init-stack-pos - ;; VAR is not on the top of the stack, so get it - (byte-compile-stack-ref init-stack-pos)) - (byte-compile-stack-ref env-vec-stack-pos) - ;; Store the variable into the vector - (byte-compile-out 'byte-vec-set env-vec-pos) - (when init-stack-pos - ;; Store nil into VAR's temporary stack - ;; position to avoid problems with GC - (byte-compile-push-constant nil) - (byte-compile-stack-set init-stack-pos)) - ;; Push a record of VAR's new lexical binding - (push (byte-compile-make-lexvar - var env-vec-pos byte-compile-current-heap-environment) - byte-compile-lexical-environment) - (not init-stack-pos))) - (t - ;; VAR is a simple stack-allocated lexical variable - (push (assq var init-lexenv) - byte-compile-lexical-environment) - nil)))) - -(defun byte-compile-unbind (clauses init-lexenv - &optional lforminfo preserve-body-value) - "Emit byte-codes to unbind the variables bound by CLAUSES. -CLAUSES is a `let'-style variable binding list. INIT-LEXENV should be a -lexical-environment alist describing the positions of the init value that -have been pushed on the stack, and LFORMINFO should be information about -the lexical variables that were bound. If PRESERVE-BODY-VALUE is true, -then an additional value on the top of the stack, above any lexical binding -slots, is preserved, so it will be on the top of the stack after all -binding slots have been popped." - ;; Unbind dynamic variables - (let ((num-dynamic-bindings 0)) - (if lforminfo - (dolist (clause clauses) - (unless (assq (if (consp clause) (car clause) clause) - (byte-compile-lforminfo-vars lforminfo)) - (setq num-dynamic-bindings (1+ num-dynamic-bindings)))) - (setq num-dynamic-bindings (length clauses))) - (unless (zerop num-dynamic-bindings) - (byte-compile-out 'byte-unbind num-dynamic-bindings))) - ;; Pop lexical variables off the stack, possibly preserving the - ;; return value of the body. - (when init-lexenv - ;; INIT-LEXENV contains all init values left on the stack - (byte-compile-discard (length init-lexenv) preserve-body-value))) - - -(provide 'byte-lexbind) - -;;; byte-lexbind.el ends here |