-;;; cconv.el --- Closure conversion for statically scoped Emacs lisp. -*- lexical-binding: t -*-
+;;; cconv.el --- Closure conversion for statically scoped Emacs lisp. -*- lexical-binding: t; coding: utf-8 -*-
-;; Copyright (C) 2011 Free Software Foundation, Inc.
+;; Copyright (C) 2011-2012 Free Software Foundation, Inc.
;; Author: Igor Kuzmin <kzuminig@iro.umontreal.ca>
;; Maintainer: FSF
;; This takes a piece of Elisp code, and eliminates all free variables from
;; lambda expressions. The user entry points are cconv-closure-convert and
-;; cconv-closure-convert-toplevel(for toplevel forms).
+;; cconv-closure-convert-toplevel (for toplevel forms).
;; All macros should be expanded beforehand.
;;
;; Here is a brief explanation how this code works.
-;; Firstly, we analyse the tree by calling cconv-analyse-form.
+;; Firstly, we analyze the tree by calling cconv-analyse-form.
;; This function finds all mutated variables, all functions that are suitable
;; for lambda lifting and all variables captured by closure. It passes the tree
;; once, returning a list of three lists.
;;
-;; Then we calculate the intersection of first and third lists returned by
+;; Then we calculate the intersection of the first and third lists returned by
;; cconv-analyse form to find all mutated variables that are captured by
;; closure.
;; Armed with this data, we call cconv-closure-convert-rec, that rewrites the
-;; tree recursivly, lifting lambdas where possible, building closures where it
+;; tree recursively, lifting lambdas where possible, building closures where it
;; is needed and eliminating mutable variables used in closure.
;;
;; We do following replacements :
;;
;;; Code:
-;;; TODO:
-;; - pay attention to `interactive': its arg is run in an empty env.
+;; TODO: (not just for cconv but also for the lexbind changes in general)
+;; - let (e)debug find the value of lexical variables from the stack.
+;; - make eval-region do the eval-sexp-add-defvars dance.
+;; - byte-optimize-form should be applied before cconv.
+;; OTOH, the warnings emitted by cconv-analyze need to come before optimize
+;; since afterwards they can because obnoxious (warnings about an "unused
+;; variable" should not be emitted when the variable use has simply been
+;; optimized away).
+;; - let macros specify that some let-bindings come from the same source,
+;; so the unused warning takes all uses into account.
+;; - let interactive specs return a function to build the args (to stash into
+;; command-history).
;; - canonize code in macro-expand so we don't have to handle (let (var) body)
;; and other oddities.
-;; - Change new byte-code representation, so it directly gives the
-;; number of mandatory and optional arguments as well as whether or
-;; not there's a &rest arg.
-;; - warn about unused lexical vars.
-;; - clean up cconv-closure-convert-rec, especially the `let' binding part.
;; - new byte codes for unwind-protect, catch, and condition-case so that
;; closures aren't needed at all.
-
-(eval-when-compile (require 'cl))
-
-(defconst cconv-liftwhen 3
+;; - inline source code of different binding mode by first compiling it.
+;; - a reference to a var that is known statically to always hold a constant
+;; should be turned into a byte-constant rather than a byte-stack-ref.
+;; Hmm... right, that's called constant propagation and could be done here,
+;; but when that constant is a function, we have to be careful to make sure
+;; the bytecomp only compiles it once.
+;; - Since we know here when a variable is not mutated, we could pass that
+;; info to the byte-compiler, e.g. by using a new `immutable-let'.
+;; - add tail-calls to bytecode.c and the byte compiler.
+;; - call known non-escaping functions with `goto' rather than `call'.
+;; - optimize mapcar to a while loop.
+
+;; (defmacro dlet (binders &rest body)
+;; ;; Works in both lexical and non-lexical mode.
+;; `(progn
+;; ,@(mapcar (lambda (binder)
+;; `(defvar ,(if (consp binder) (car binder) binder)))
+;; binders)
+;; (let ,binders ,@body)))
+
+;; (defmacro llet (binders &rest body)
+;; ;; Only works in lexical-binding mode.
+;; `(funcall
+;; (lambda ,(mapcar (lambda (binder) (if (consp binder) (car binder) binder))
+;; binders)
+;; ,@body)
+;; ,@(mapcar (lambda (binder) (if (consp binder) (cadr binder)))
+;; binders)))
+
+(eval-when-compile (require 'cl-lib))
+
+(defconst cconv-liftwhen 6
"Try to do lambda lifting if the number of arguments + free variables
is less than this number.")
;; List of all the variables that are both captured by a closure
(let ((cconv-freevars-alist '())
(cconv-lambda-candidates '())
(cconv-captured+mutated '()))
- ;; Analyse form - fill these variables with new information.
+ ;; Analyze form - fill these variables with new information.
(cconv-analyse-form form '())
(setq cconv-freevars-alist (nreverse cconv-freevars-alist))
- (cconv-closure-convert-rec
- form ; the tree
- '() ;
- '() ; fvrs initially empty
- '() ; envs initially empty
- '()
- )))
+ (cconv-convert form nil nil))) ; Env initially empty.
(defconst cconv--dummy-var (make-symbol "ignored"))
;; Here we assume that X appears at most once in M.
(let* ((b (assq x m))
(res (if b (remq b m) m)))
- (assert (null (assq x res))) ;; Check the assumption was warranted.
+ (cl-assert (null (assq x res))) ;; Check the assumption was warranted.
res))
(defun cconv--map-diff-set (m s)
(unless (memq (car b) s) (push b res)))
(nreverse res)))
-(defun cconv-closure-convert-function (fvrs vars emvrs envs lmenvs body-forms
- parentform)
- (assert (equal body-forms (caar cconv-freevars-alist)))
- (let* ((fvrs-new (cconv--set-diff fvrs vars)) ; Remove vars from fvrs.
- (fv (cdr (pop cconv-freevars-alist)))
- (body-forms-new '())
+(defun cconv--convert-function (args body env parentform)
+ (cl-assert (equal body (caar cconv-freevars-alist)))
+ (let* ((fvs (cdr (pop cconv-freevars-alist)))
+ (body-new '())
(letbind '())
- (envector nil))
- (when fv
- ;; Here we form our environment vector.
-
- (dolist (elm fv)
- (push
- (cconv-closure-convert-rec
- ;; Remove `elm' from `emvrs' for this call because in case
- ;; `elm' is a variable that's wrapped in a cons-cell, we
- ;; want to put the cons-cell itself in the closure, rather
- ;; than just a copy of its current content.
- elm (remq elm emvrs) fvrs envs lmenvs)
- envector)) ; Process vars for closure vector.
- (setq envector (reverse envector))
- (setq envs fv)
- (setq fvrs-new fv)) ; Update substitution list.
-
- (setq emvrs (cconv--set-diff emvrs vars))
- (setq lmenvs (cconv--map-diff-set lmenvs vars))
-
- ;; The difference between envs and fvrs is explained
- ;; in comment in the beginning of the function.
- (dolist (var vars)
- (when (member (cons (list var) parentform) cconv-captured+mutated)
- (push var emvrs)
- (push `(,var (list ,var)) letbind)))
- (dolist (elm body-forms) ; convert function body
- (push (cconv-closure-convert-rec
- elm emvrs fvrs-new envs lmenvs)
- body-forms-new))
-
- (setq body-forms-new
- (if letbind `((let ,letbind . ,(reverse body-forms-new)))
- (reverse body-forms-new)))
+ (envector ())
+ (i 0)
+ (new-env ()))
+ ;; Build the "formal and actual envs" for the closure-converted function.
+ (dolist (fv fvs)
+ (let ((exp (or (cdr (assq fv env)) fv)))
+ (pcase exp
+ ;; If `fv' is a variable that's wrapped in a cons-cell,
+ ;; we want to put the cons-cell itself in the closure,
+ ;; rather than just a copy of its current content.
+ (`(car ,iexp . ,_)
+ (push iexp envector)
+ (push `(,fv . (car (internal-get-closed-var ,i))) new-env))
+ (_
+ (push exp envector)
+ (push `(,fv . (internal-get-closed-var ,i)) new-env))))
+ (setq i (1+ i)))
+ (setq envector (nreverse envector))
+ (setq new-env (nreverse new-env))
+
+ (dolist (arg args)
+ (if (not (member (cons (list arg) parentform) cconv-captured+mutated))
+ (if (assq arg new-env) (push `(,arg) new-env))
+ (push `(,arg . (car ,arg)) new-env)
+ (push `(,arg (list ,arg)) letbind)))
+
+ (setq body-new (mapcar (lambda (form)
+ (cconv-convert form new-env nil))
+ body))
+
+ (when letbind
+ (let ((special-forms '()))
+ ;; Keep special forms at the beginning of the body.
+ (while (or (stringp (car body-new)) ;docstring.
+ (memq (car-safe (car body-new)) '(interactive declare)))
+ (push (pop body-new) special-forms))
+ (setq body-new
+ `(,@(nreverse special-forms) (let ,letbind . ,body-new)))))
(cond
- ;if no freevars - do nothing
- ((null envector)
- `(function (lambda ,vars . ,body-forms-new)))
- ; 1 free variable - do not build vector
+ ((null envector) ;if no freevars - do nothing
+ `(function (lambda ,args . ,body-new)))
(t
`(internal-make-closure
- ,vars ,envector . ,body-forms-new)))))
+ ,args ,envector . ,body-new)))))
-(defun cconv-closure-convert-rec (form emvrs fvrs envs lmenvs)
+(defun cconv-convert (form env extend)
;; This function actually rewrites the tree.
- "Eliminates all free variables of all lambdas in given forms.
-Arguments:
--- FORM is a piece of Elisp code after macroexpansion.
--- LMENVS is a list of environments used for lambda-lifting. Initially empty.
--- EMVRS is a list that contains mutated variables that are visible
-within current environment.
--- ENVS is an environment(list of free variables) of current closure.
-Initially empty.
--- FVRS is a list of variables to substitute in each context.
-Initially empty.
+ "Return FORM with all its lambdas changed so they are closed.
+ENV is a lexical environment mapping variables to the expression
+used to get its value. This is used for variables that are copied into
+closures, moved into cons cells, ...
+ENV is a list where each entry takes the shape either:
+ (VAR . (car EXP)): VAR has been moved into the car of a cons-cell, and EXP
+ is an expression that evaluates to this cons-cell.
+ (VAR . (internal-get-closed-var N)): VAR has been copied into the closure
+ environment's Nth slot.
+ (VAR . (apply-partially F ARG1 ARG2 ..)): VAR has been λ-lifted and takes
+ additional arguments ARGs.
+EXTEND is a list of variables which might need to be accessed even from places
+where they are shadowed, because some part of ENV causes them to be used at
+places where they originally did not directly appear."
+ (cl-assert (not (delq nil (mapcar (lambda (mapping)
+ (if (eq (cadr mapping) 'apply-partially)
+ (cconv--set-diff (cdr (cddr mapping))
+ extend)))
+ env))))
-Returns a form where all lambdas don't have any free variables."
;; What's the difference between fvrs and envs?
;; Suppose that we have the code
;; (lambda (..) fvr (let ((fvr 1)) (+ fvr 1)))
;; so we never touch it(unless we enter to the other closure).
;;(if (listp form) (print (car form)) form)
(pcase form
- (`(,(and letsym (or `let* `let)) ,binders . ,body-forms)
+ (`(,(and letsym (or `let* `let)) ,binders . ,body)
; let and let* special forms
- (let ((body-forms-new '())
- (binders-new '())
- ;; next for variables needed for delayed push
- ;; because we should process <value(s)>
- ;; before we change any arguments
- (lmenvs-new '()) ;needed only in case of let
- (emvrs-new '()) ;needed only in case of let
- (emvr-push) ;needed only in case of let*
- (lmenv-push)) ;needed only in case of let*
+ (let ((binders-new '())
+ (new-env env)
+ (new-extend extend))
(dolist (binder binders)
(let* ((value nil)
(new-val
(cond
;; Check if var is a candidate for lambda lifting.
- ((member (cons binder form) cconv-lambda-candidates)
- (assert (and (eq (car value) 'function)
- (eq (car (cadr value)) 'lambda)))
- (assert (equal (cddr (cadr value))
- (caar cconv-freevars-alist)))
- (let* ((fv (cdr (pop cconv-freevars-alist)))
- (funargs (cadr (cadr value)))
- (funcvars (append fv funargs))
- (funcbodies (cddadr value)) ; function bodies
- (funcbodies-new '()))
+ ((and (member (cons binder form) cconv-lambda-candidates)
+ (progn
+ (cl-assert (and (eq (car value) 'function)
+ (eq (car (cadr value)) 'lambda)))
+ (cl-assert (equal (cddr (cadr value))
+ (caar cconv-freevars-alist)))
+ ;; Peek at the freevars to decide whether to λ-lift.
+ (let* ((fvs (cdr (car cconv-freevars-alist)))
+ (fun (cadr value))
+ (funargs (cadr fun))
+ (funcvars (append fvs funargs)))
; lambda lifting condition
- (if (or (not fv) (< cconv-liftwhen (length funcvars)))
- ; do not lift
- (cconv-closure-convert-rec
- value emvrs fvrs envs lmenvs)
- ; lift
- (progn
- (dolist (elm2 funcbodies)
- (push ; convert function bodies
- (cconv-closure-convert-rec
- elm2 emvrs nil envs lmenvs)
- funcbodies-new))
- (if (eq letsym 'let*)
- (setq lmenv-push (cons var fv))
- (push (cons var fv) lmenvs-new))
- ; push lifted function
-
- `(function .
- ((lambda ,funcvars .
- ,(reverse funcbodies-new))))))))
+ (and fvs (>= cconv-liftwhen (length funcvars))))))
+ ; Lift.
+ (let* ((fvs (cdr (pop cconv-freevars-alist)))
+ (fun (cadr value))
+ (funargs (cadr fun))
+ (funcvars (append fvs funargs))
+ (funcbody (cddr fun))
+ (funcbody-env ()))
+ (push `(,var . (apply-partially ,var . ,fvs)) new-env)
+ (dolist (fv fvs)
+ (cl-pushnew fv new-extend)
+ (if (and (eq 'car (car-safe (cdr (assq fv env))))
+ (not (memq fv funargs)))
+ (push `(,fv . (car ,fv)) funcbody-env)))
+ `(function (lambda ,funcvars .
+ ,(mapcar (lambda (form)
+ (cconv-convert
+ form funcbody-env nil))
+ funcbody)))))
;; Check if it needs to be turned into a "ref-cell".
((member (cons binder form) cconv-captured+mutated)
;; Declared variable is mutated and captured.
- (prog1
- `(list ,(cconv-closure-convert-rec
- value emvrs
- fvrs envs lmenvs))
- (if (eq letsym 'let*)
- (setq emvr-push var)
- (push var emvrs-new))))
+ (push `(,var . (car ,var)) new-env)
+ `(list ,(cconv-convert value env extend)))
;; Normal default case.
(t
- (cconv-closure-convert-rec
- value emvrs fvrs envs lmenvs)))))
-
- ;; this piece of code below letbinds free
- ;; variables of a lambda lifted function
- ;; if they are redefined in this let
- ;; example:
- ;; (let* ((fun (lambda (x) (+ x y))) (y 1)) (funcall fun 1))
- ;; Here we can not pass y as parameter because it is
- ;; redefined. We add a (closed-y y) declaration.
- ;; We do that even if the function is not used inside
- ;; this let(*). The reason why we ignore this case is
- ;; that we can't "look forward" to see if the function
- ;; is called there or not. To treat well this case we
- ;; need to traverse the tree one more time to collect this
- ;; data, and I think that it's not worth it.
+ (if (assq var new-env) (push `(,var) new-env))
+ (cconv-convert value env extend)))))
+
+ ;; The piece of code below letbinds free variables of a λ-lifted
+ ;; function if they are redefined in this let, example:
+ ;; (let* ((fun (lambda (x) (+ x y))) (y 1)) (funcall fun 1))
+ ;; Here we can not pass y as parameter because it is redefined.
+ ;; So we add a (closed-y y) declaration. We do that even if the
+ ;; function is not used inside this let(*). The reason why we
+ ;; ignore this case is that we can't "look forward" to see if the
+ ;; function is called there or not. To treat this case better we'd
+ ;; need to traverse the tree one more time to collect this data, and
+ ;; I think that it's not worth it.
+ (when (memq var new-extend)
+ (let ((closedsym
+ (make-symbol (concat "closed-" (symbol-name var)))))
+ (setq new-env
+ (mapcar (lambda (mapping)
+ (if (not (eq (cadr mapping) 'apply-partially))
+ mapping
+ (cl-assert (eq (car mapping) (nth 2 mapping)))
+ `(,(car mapping)
+ apply-partially
+ ,(car mapping)
+ ,@(mapcar (lambda (arg)
+ (if (eq var arg)
+ closedsym arg))
+ (nthcdr 3 mapping)))))
+ new-env))
+ (setq new-extend (remq var new-extend))
+ (push closedsym new-extend)
+ (push `(,closedsym ,var) binders-new)))
- (when (eq letsym 'let*)
- (let ((closedsym '())
- (new-lmenv '())
- (old-lmenv '()))
- (dolist (lmenv lmenvs)
- (when (memq var (cdr lmenv))
- (setq closedsym
- (make-symbol
- (concat "closed-" (symbol-name var))))
- (setq new-lmenv (list (car lmenv)))
- (dolist (frv (cdr lmenv)) (if (eq frv var)
- (push closedsym new-lmenv)
- (push frv new-lmenv)))
- (setq new-lmenv (reverse new-lmenv))
- (setq old-lmenv lmenv)))
- (when new-lmenv
- (setq lmenvs (remq old-lmenv lmenvs))
- (push new-lmenv lmenvs)
- (push `(,closedsym ,var) binders-new))))
;; We push the element after redefined free variables are
;; processed. This is important to avoid the bug when free
;; variable and the function have the same name.
(push (list var new-val) binders-new)
- (when (eq letsym 'let*) ; update fvrs
- (setq fvrs (remq var fvrs))
- (setq emvrs (remq var emvrs)) ; remove if redefined
- (when emvr-push
- (push emvr-push emvrs)
- (setq emvr-push nil))
- (setq lmenvs (cconv--map-diff-elem lmenvs var))
- (when lmenv-push
- (push lmenv-push lmenvs)
- (setq lmenv-push nil)))
- )) ; end of dolist over binders
- (when (eq letsym 'let)
-
- ;; Here we update emvrs, fvrs and lmenvs lists
- (setq fvrs (cconv--set-diff-map fvrs binders-new))
- (setq emvrs (cconv--set-diff-map emvrs binders-new))
- (setq emvrs (append emvrs emvrs-new))
- (setq lmenvs (cconv--set-diff-map lmenvs binders-new))
- (setq lmenvs (append lmenvs lmenvs-new))
-
- ;; Here we do the same letbinding as for let* above
- ;; to avoid situation when a free variable of a lambda lifted
- ;; function got redefined.
-
- (let ((new-lmenv)
- (var nil)
- (closedsym nil)
- (letbinds '()))
- (dolist (binder binders)
- (setq var (if (consp binder) (car binder) binder))
-
- (let ((lmenvs-1 lmenvs)) ; just to avoid manipulating
- (dolist (lmenv lmenvs-1) ; the counter inside the loop
- (when (memq var (cdr lmenv))
- (setq closedsym (make-symbol
- (concat "closed-"
- (symbol-name var))))
-
- (setq new-lmenv (list (car lmenv)))
- (dolist (frv (cdr lmenv))
- (push (if (eq frv var) closedsym frv)
- new-lmenv))
- (setq new-lmenv (reverse new-lmenv))
- (setq lmenvs (remq lmenv lmenvs))
- (push new-lmenv lmenvs)
- (push `(,closedsym ,var) letbinds)
- ))))
- (setq binders-new (append binders-new letbinds))))
-
- (dolist (elm body-forms) ; convert body forms
- (push (cconv-closure-convert-rec
- elm emvrs fvrs envs lmenvs)
- body-forms-new))
- `(,letsym ,(reverse binders-new) . ,(reverse body-forms-new))))
+ (when (eq letsym 'let*)
+ (setq env new-env)
+ (setq extend new-extend))
+ )) ; end of dolist over binders
+
+ `(,letsym ,(nreverse binders-new)
+ . ,(mapcar (lambda (form)
+ (cconv-convert
+ form new-env new-extend))
+ body))))
;end of let let* forms
; first element is lambda expression
- (`(,(and `(lambda . ,_) fun) . ,other-body-forms)
-
- (let ((other-body-forms-new '()))
- (dolist (elm other-body-forms)
- (push (cconv-closure-convert-rec
- elm emvrs fvrs envs lmenvs)
- other-body-forms-new))
- `(funcall
- ,(cconv-closure-convert-rec
- (list 'function fun) emvrs fvrs envs lmenvs)
- ,@(nreverse other-body-forms-new))))
+ (`(,(and `(lambda . ,_) fun) . ,args)
+ ;; FIXME: it's silly to create a closure just to call it.
+ ;; Running byte-optimize-form earlier will resolve this.
+ `(funcall
+ ,(cconv-convert `(function ,fun) env extend)
+ ,@(mapcar (lambda (form)
+ (cconv-convert form env extend))
+ args)))
(`(cond . ,cond-forms) ; cond special form
- (let ((cond-forms-new '()))
- (dolist (elm cond-forms)
- (push (let ((elm-new '()))
- (dolist (elm-2 elm)
- (push
- (cconv-closure-convert-rec
- elm-2 emvrs fvrs envs lmenvs)
- elm-new))
- (reverse elm-new))
- cond-forms-new))
- (cons 'cond
- (reverse cond-forms-new))))
-
- (`(quote . ,_) form)
+ `(cond . ,(mapcar (lambda (branch)
+ (mapcar (lambda (form)
+ (cconv-convert form env extend))
+ branch))
+ cond-forms)))
- (`(function (lambda ,vars . ,body-forms)) ; function form
- (cconv-closure-convert-function
- fvrs vars emvrs envs lmenvs body-forms form))
+ (`(function (lambda ,args . ,body) . ,_)
+ (cconv--convert-function args body env form))
(`(internal-make-closure . ,_)
- (error "Internal byte-compiler error: cconv called twice"))
+ (byte-compile-report-error
+ "Internal error in compiler: cconv called twice?"))
- (`(function . ,_) form) ; Same as quote.
+ (`(quote . ,_) form)
+ (`(function . ,_) form)
;defconst, defvar
- (`(,(and sym (or `defconst `defvar)) ,definedsymbol . ,body-forms)
-
- (let ((body-forms-new '()))
- (dolist (elm body-forms)
- (push (cconv-closure-convert-rec
- elm emvrs fvrs envs lmenvs)
- body-forms-new))
- (setq body-forms-new (reverse body-forms-new))
- `(,sym ,definedsymbol . ,body-forms-new)))
-
- ;defun, defmacro
- (`(,(and sym (or `defun `defmacro))
- ,func ,vars . ,body-forms)
-
- ;; The freevar data was pushed onto cconv-freevars-alist
- ;; but we don't need it.
- (assert (equal body-forms (caar cconv-freevars-alist)))
- (assert (null (cdar cconv-freevars-alist)))
- (setq cconv-freevars-alist (cdr cconv-freevars-alist))
-
- (let ((body-new '()) ; The whole body.
- (body-forms-new '()) ; Body w\o docstring and interactive.
- (letbind '()))
- ; Find mutable arguments.
- (dolist (elm vars)
- (when (member (cons (list elm) form) cconv-captured+mutated)
- (push elm letbind)
- (push elm emvrs)))
- ;Transform body-forms.
- (when (stringp (car body-forms)) ; Treat docstring well.
- (push (car body-forms) body-new)
- (setq body-forms (cdr body-forms)))
- (when (eq (car-safe (car body-forms)) 'interactive)
- (push (cconv-closure-convert-rec
- (car body-forms)
- emvrs fvrs envs lmenvs)
- body-new)
- (setq body-forms (cdr body-forms)))
-
- (dolist (elm body-forms)
- (push (cconv-closure-convert-rec
- elm emvrs fvrs envs lmenvs)
- body-forms-new))
- (setq body-forms-new (reverse body-forms-new))
-
- (if letbind
- ; Letbind mutable arguments.
- (let ((binders-new '()))
- (dolist (elm letbind) (push `(,elm (list ,elm))
- binders-new))
- (push `(let ,(reverse binders-new) .
- ,body-forms-new) body-new)
- (setq body-new (reverse body-new)))
- (setq body-new (append (reverse body-new) body-forms-new)))
-
- `(,sym ,func ,vars . ,body-new)))
+ (`(,(and sym (or `defconst `defvar)) ,definedsymbol . ,forms)
+ `(,sym ,definedsymbol
+ . ,(mapcar (lambda (form) (cconv-convert form env extend))
+ forms)))
;condition-case
(`(condition-case ,var ,protected-form . ,handlers)
- (let ((newform (cconv-closure-convert-rec
- `(function (lambda () ,protected-form))
- emvrs fvrs envs lmenvs)))
- (setq fvrs (remq var fvrs))
+ (let ((newform (cconv--convert-function
+ () (list protected-form) env form)))
`(condition-case :fun-body ,newform
,@(mapcar (lambda (handler)
(list (car handler)
- (cconv-closure-convert-rec
- (let ((arg (or var cconv--dummy-var)))
- `(function (lambda (,arg) ,@(cdr handler))))
- emvrs fvrs envs lmenvs)))
+ (cconv--convert-function
+ (list (or var cconv--dummy-var))
+ (cdr handler) env form)))
handlers))))
(`(,(and head (or `catch `unwind-protect)) ,form . ,body)
- `(,head ,(cconv-closure-convert-rec form emvrs fvrs envs lmenvs)
- :fun-body
- ,(cconv-closure-convert-rec `(function (lambda () ,@body))
- emvrs fvrs envs lmenvs)))
+ `(,head ,(cconv-convert form env extend)
+ :fun-body ,(cconv--convert-function () body env form)))
(`(track-mouse . ,body)
`(track-mouse
- :fun-body
- ,(cconv-closure-convert-rec `(function (lambda () ,@body))
- emvrs fvrs envs lmenvs)))
+ :fun-body ,(cconv--convert-function () body env form)))
(`(setq . ,forms) ; setq special form
- (let (prognlist sym sym-new value)
+ (let ((prognlist ()))
(while forms
- (setq sym (car forms))
- (setq sym-new (cconv-closure-convert-rec
- sym
- (remq sym emvrs) fvrs envs lmenvs))
- (setq value
- (cconv-closure-convert-rec
- (cadr forms) emvrs fvrs envs lmenvs))
- (cond
- ((memq sym emvrs) (push `(setcar ,sym-new ,value) prognlist))
- ((symbolp sym-new) (push `(setq ,sym-new ,value) prognlist))
- ;; This should never happen, but for variables which are
- ;; mutated+captured+unused, we may end up trying to `setq'
- ;; on a closed-over variable, so just drop the setq.
- (t (push value prognlist)))
- (setq forms (cddr forms)))
+ (let* ((sym (pop forms))
+ (sym-new (or (cdr (assq sym env)) sym))
+ (value (cconv-convert (pop forms) env extend)))
+ (push (pcase sym-new
+ ((pred symbolp) `(setq ,sym-new ,value))
+ (`(car ,iexp) `(setcar ,iexp ,value))
+ ;; This "should never happen", but for variables which are
+ ;; mutated+captured+unused, we may end up trying to `setq'
+ ;; on a closed-over variable, so just drop the setq.
+ (_ ;; (byte-compile-report-error
+ ;; (format "Internal error in cconv of (setq %s ..)"
+ ;; sym-new))
+ value))
+ prognlist)))
(if (cdr prognlist)
- `(progn . ,(reverse prognlist))
+ `(progn . ,(nreverse prognlist))
(car prognlist))))
(`(,(and (or `funcall `apply) callsym) ,fun . ,args)
- ; funcall is not a special form
- ; but we treat it separately
- ; for the needs of lambda lifting
- (let ((fv (cdr (assq fun lmenvs))))
- (if fv
- (let ((args-new '())
- (processed-fv '()))
- ;; All args (free variables and actual arguments)
- ;; should be processed, because they can be fvrs
- ;; (free variables of another closure)
- (dolist (fvr fv)
- (push (cconv-closure-convert-rec
- fvr (remq fvr emvrs)
- fvrs envs lmenvs)
- processed-fv))
- (setq processed-fv (reverse processed-fv))
- (dolist (elm args)
- (push (cconv-closure-convert-rec
- elm emvrs fvrs envs lmenvs)
- args-new))
- (setq args-new (append processed-fv (reverse args-new)))
- (setq fun (cconv-closure-convert-rec
- fun emvrs fvrs envs lmenvs))
- `(,callsym ,fun . ,args-new))
- (let ((cdr-new '()))
- (dolist (elm (cdr form))
- (push (cconv-closure-convert-rec
- elm emvrs fvrs envs lmenvs)
- cdr-new))
- `(,callsym . ,(reverse cdr-new))))))
-
- (`(,func . ,body-forms) ; first element is function or whatever
- ; function-like forms are:
- ; or, and, if, progn, prog1, prog2,
- ; while, until
- (let ((body-forms-new '()))
- (dolist (elm body-forms)
- (push (cconv-closure-convert-rec
- elm emvrs fvrs envs lmenvs)
- body-forms-new))
- (setq body-forms-new (reverse body-forms-new))
- `(,func . ,body-forms-new)))
-
- (_
- (let ((free (memq form fvrs)))
- (if free ;form is a free variable
- (let* ((numero (- (length fvrs) (length free)))
- ;; Replace form => (aref env #)
- (var `(internal-get-closed-var ,numero)))
- (if (memq form emvrs) ; form => (car (aref env #)) if mutable
- `(car ,var)
- var))
- (if (memq form emvrs) ; if form is a mutable variable
- `(car ,form) ; replace form => (car form)
- form))))))
+ ;; These are not special forms but we treat them separately for the needs
+ ;; of lambda lifting.
+ (let ((mapping (cdr (assq fun env))))
+ (pcase mapping
+ (`(apply-partially ,_ . ,(and fvs `(,_ . ,_)))
+ (cl-assert (eq (cadr mapping) fun))
+ `(,callsym ,fun
+ ,@(mapcar (lambda (fv)
+ (let ((exp (or (cdr (assq fv env)) fv)))
+ (pcase exp
+ (`(car ,iexp . ,_) iexp)
+ (_ exp))))
+ fvs)
+ ,@(mapcar (lambda (arg)
+ (cconv-convert arg env extend))
+ args)))
+ (_ `(,callsym ,@(mapcar (lambda (arg)
+ (cconv-convert arg env extend))
+ (cons fun args)))))))
+
+ (`(interactive . ,forms)
+ `(interactive . ,(mapcar (lambda (form)
+ (cconv-convert form nil nil))
+ forms)))
+
+ (`(declare . ,_) form) ;The args don't contain code.
+
+ (`(,func . ,forms)
+ ;; First element is function or whatever function-like forms are: or, and,
+ ;; if, progn, prog1, prog2, while, until
+ `(,func . ,(mapcar (lambda (form)
+ (cconv-convert form env extend))
+ forms)))
+
+ (_ (or (cdr (assq form env)) form))))
(unless (fboundp 'byte-compile-not-lexical-var-p)
;; Only used to test the code in non-lexbind Emacs.
(defalias 'byte-compile-not-lexical-var-p 'boundp))
-(defun cconv-analyse-use (vardata form)
+(defun cconv--analyse-use (vardata form varkind)
+ "Analyze the use of a variable.
+VARDATA should be (BINDER READ MUTATED CAPTURED CALLED).
+VARKIND is the name of the kind of variable.
+FORM is the parent form that binds this var."
;; use = `(,binder ,read ,mutated ,captured ,called)
(pcase vardata
- (`(,binder nil ,_ ,_ nil)
- ;; FIXME: Don't warn about unused fun-args.
- ;; FIXME: Don't warn about uninterned vars or _ vars.
- ;; FIXME: This gives warnings in the wrong order and with wrong line
- ;; number and without function name info.
- (byte-compile-log-warning (format "Unused variable %S" (car binder))))
+ (`(,_ nil nil nil nil) nil)
+ (`((,(and (pred (lambda (var) (eq ?_ (aref (symbol-name var) 0)))) var) . ,_)
+ ,_ ,_ ,_ ,_)
+ (byte-compile-log-warning
+ (format "%s `%S' not left unused" varkind var))))
+ (pcase vardata
+ (`((,var . ,_) nil ,_ ,_ nil)
+ ;; FIXME: This gives warnings in the wrong order, with imprecise line
+ ;; numbers and without function name info.
+ (unless (or ;; Uninterned symbols typically come from macro-expansion, so
+ ;; it is often non-trivial for the programmer to avoid such
+ ;; unused vars.
+ (not (intern-soft var))
+ (eq ?_ (aref (symbol-name var) 0))
+ ;; As a special exception, ignore "ignore".
+ (eq var 'ignored))
+ (byte-compile-log-warning (format "Unused lexical %s `%S'"
+ varkind var))))
;; If it's unused, there's no point converting it into a cons-cell, even if
- ;; it's captures and mutated.
+ ;; it's captured and mutated.
(`(,binder ,_ t t ,_)
(push (cons binder form) cconv-captured+mutated))
(`(,(and binder `(,_ (function (lambda . ,_)))) nil nil nil t)
- ;; This is very rare in typical Elisp code. It's probably not really
- ;; worth the trouble to try and use lambda-lifting in Elisp, but
- ;; since we coded it up, we might as well use it.
- (push (cons binder form) cconv-lambda-candidates))
- (`(,_ ,_ ,_ ,_ ,_) nil)
- (dontcare)))
-
-(defun cconv-analyse-function (args body env parentform)
+ (push (cons binder form) cconv-lambda-candidates))))
+
+(defun cconv--analyse-function (args body env parentform)
(let* ((newvars nil)
(freevars (list body))
;; We analyze the body within a new environment where all uses are
(dolist (arg args)
(cond
((byte-compile-not-lexical-var-p arg)
- (byte-compile-report-error
+ (byte-compile-log-warning
(format "Argument %S is not a lexical variable" arg)))
((eq ?& (aref (symbol-name arg) 0)) nil) ;Ignore &rest, &optional, ...
(t (let ((varstruct (list arg nil nil nil nil)))
(push (cons (list arg) (cdr varstruct)) newvars)
(push varstruct newenv)))))
- (dolist (form body) ;Analyse body forms.
+ (dolist (form body) ;Analyze body forms.
(cconv-analyse-form form newenv))
;; Summarize resulting data about arguments.
(dolist (vardata newvars)
- (cconv-analyse-use vardata parentform))
+ (cconv--analyse-use vardata parentform "argument"))
;; Transfer uses collected in `envcopy' (via `newenv') back to `env';
;; and compute free variables.
(while env
- (assert (and envcopy (eq (caar env) (caar envcopy))))
+ (cl-assert (and envcopy (eq (caar env) (caar envcopy))))
(let ((free nil)
(x (cdr (car env)))
(y (cdr (car envcopy))))
(defun cconv-analyse-form (form env)
"Find mutated variables and variables captured by closure.
-Analyse lambdas if they are suitable for lambda lifting.
--- FORM is a piece of Elisp code after macroexpansion.
--- ENV is an alist mapping each enclosing lexical variable to its info.
+Analyze lambdas if they are suitable for lambda lifting.
+- FORM is a piece of Elisp code after macroexpansion.
+- ENV is an alist mapping each enclosing lexical variable to its info.
I.e. each element has the form (VAR . (READ MUTATED CAPTURED CALLED)).
This function does not return anything but instead fills the
`cconv-captured+mutated' and `cconv-lambda-candidates' variables
(push (cons binder (cdr varstruct)) newvars)
(push varstruct env))))
- (dolist (form body-forms) ; Analyse body forms.
+ (dolist (form body-forms) ; Analyze body forms.
(cconv-analyse-form form env))
(dolist (vardata newvars)
- (cconv-analyse-use vardata form))))
-
- ; defun special form
- (`(,(or `defun `defmacro) ,func ,vrs . ,body-forms)
- (when env
- (byte-compile-log-warning
- (format "Function %S will ignore its context %S"
- func (mapcar #'car env))
- t :warning))
- (cconv-analyse-function vrs body-forms nil form))
+ (cconv--analyse-use vardata form "variable"))))
(`(function (lambda ,vrs . ,body-forms))
- (cconv-analyse-function vrs body-forms env form))
-
+ (cconv--analyse-function vrs body-forms env form))
+
(`(setq . ,forms)
;; If a local variable (member of env) is modified by setq then
;; it is a mutated variable.
(cconv-analyse-form (cadr forms) env)
(setq forms (cddr forms))))
- (`((lambda . ,_) . ,_) ; first element is lambda expression
+ (`((lambda . ,_) . ,_) ; First element is lambda expression.
+ (byte-compile-log-warning
+ "Use of deprecated ((lambda ...) ...) form" t :warning)
(dolist (exp `((function ,(car form)) . ,(cdr form)))
(cconv-analyse-form exp env)))
(`(cond . ,cond-forms) ; cond special form
(dolist (forms cond-forms)
- (dolist (form forms)
- (cconv-analyse-form form env))))
+ (dolist (form forms) (cconv-analyse-form form env))))
(`(quote . ,_) nil) ; quote form
(`(function . ,_) nil) ; same as quote
(`(condition-case ,var ,protected-form . ,handlers)
;; FIXME: The bytecode for condition-case forces us to wrap the
- ;; form and handlers in closures (for handlers, it's probably
- ;; unavoidable, but not for the protected form).
- (cconv-analyse-function () (list protected-form) env form)
+ ;; form and handlers in closures (for handlers, it's understandable
+ ;; but not for the protected form).
+ (cconv--analyse-function () (list protected-form) env form)
(dolist (handler handlers)
- (cconv-analyse-function (if var (list var)) (cdr handler) env form)))
+ (cconv--analyse-function (if var (list var)) (cdr handler) env form)))
;; FIXME: The bytecode for catch forces us to wrap the body.
(`(,(or `catch `unwind-protect) ,form . ,body)
(cconv-analyse-form form env)
- (cconv-analyse-function () body env form))
+ (cconv--analyse-function () body env form))
- ;; FIXME: The bytecode for save-window-excursion and the lack of
- ;; bytecode for track-mouse forces us to wrap the body.
+ ;; FIXME: The lack of bytecode for track-mouse forces us to wrap the body.
+ ;; `track-mouse' really should be made into a macro.
(`(track-mouse . ,body)
- (cconv-analyse-function () body env form))
+ (cconv--analyse-function () body env form))
(`(,(or `defconst `defvar) ,var ,value . ,_)
(push var byte-compile-bound-variables)
(if fdata
(setf (nth 4 fdata) t)
(cconv-analyse-form fun env)))
- (dolist (form args)
- (cconv-analyse-form form env)))
+ (dolist (form args) (cconv-analyse-form form env)))
+
+ (`(interactive . ,forms)
+ ;; These appear within the function body but they don't have access
+ ;; to the function's arguments.
+ ;; We could extend this to allow interactive specs to refer to
+ ;; variables in the function's enclosing environment, but it doesn't
+ ;; seem worth the trouble.
+ (dolist (form forms) (cconv-analyse-form form nil)))
+
+ (`(declare . ,_) nil) ;The args don't contain code.
(`(,_ . ,body-forms) ; First element is a function or whatever.
- (dolist (form body-forms)
- (cconv-analyse-form form env)))
+ (dolist (form body-forms) (cconv-analyse-form form env)))
((pred symbolp)
(let ((dv (assq form env))) ; dv = declared and visible