;;; Tree-IL partial evaluator
-;; Copyright (C) 2011, 2012 Free Software Foundation, Inc.
+;; Copyright (C) 2011, 2012, 2013 Free Software Foundation, Inc.
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-11)
#:use-module (srfi srfi-26)
+ #:use-module (ice-9 control)
#:export (peval))
;;;
(newline)
(values)))
-(define-syntax-rule (let/ec k e e* ...)
- (let ((tag (make-prompt-tag)))
- (call-with-prompt
- tag
- (lambda ()
- (let ((k (lambda args (apply abort-to-prompt tag args))))
- e e* ...))
- (lambda (_ res) res))))
-
(define (tree-il-any proc exp)
(let/ec k
(tree-il-fold (lambda (exp res)
(let ((res (proc exp)))
(if res (k res) #f)))
- (lambda (exp res)
- (let ((res (proc exp)))
- (if res (k res) #f)))
(lambda (exp res) #f)
#f exp)))
(($ <primcall> _ (? singly-valued-primitive?)) #t)
(($ <primcall> _ 'values (val)) #t)
(($ <lambda>) #t)
+ (($ <conditional> _ test consequent alternate)
+ (and (singly-valued-expression? consequent)
+ (singly-valued-expression? alternate)))
(else #f)))
(define (truncate-values x)
(let ((var (cdr (vhash-assq gensym res))))
(set-var-refcount! var (1+ (var-refcount var)))
res))
- (_ res)))
- (lambda (exp res)
- (match exp
(($ <lambda-case> src req opt rest kw init gensyms body alt)
(fold (lambda (name sym res)
(vhash-consq sym (make-var name sym 0 #f) res))
(define (fresh-gensyms vars)
(map (lambda (var)
(let ((new (gensym (string-append (symbol->string (var-name var))
- "-"))))
+ " "))))
(set! store (vhash-consq new var store))
new))
vars))
+ (define (fresh-temporaries ls)
+ (map (lambda (elt)
+ (let ((new (gensym "tmp ")))
+ (record-new-temporary! 'tmp new 1)
+ new))
+ ls))
+
(define (assigned-lexical? sym)
(var-set? (lookup-var sym)))
(define (lexical-refcount sym)
(var-refcount (lookup-var sym)))
+ (define (with-temporaries src exps refcount can-copy? k)
+ (let* ((pairs (map (match-lambda
+ ((and exp (? can-copy?))
+ (cons #f exp))
+ (exp
+ (let ((sym (gensym "tmp ")))
+ (record-new-temporary! 'tmp sym refcount)
+ (cons sym exp))))
+ exps))
+ (tmps (filter car pairs)))
+ (match tmps
+ (() (k exps))
+ (tmps
+ (make-let src
+ (make-list (length tmps) 'tmp)
+ (map car tmps)
+ (map cdr tmps)
+ (k (map (match-lambda
+ ((#f . val) val)
+ ((sym . _)
+ (make-lexical-ref #f 'tmp sym)))
+ pairs)))))))
+
+ (define (make-begin0 src first second)
+ (make-let-values
+ src
+ first
+ (let ((vals (gensym "vals ")))
+ (record-new-temporary! 'vals vals 1)
+ (make-lambda-case
+ #f
+ '() #f 'vals #f '() (list vals)
+ (make-seq
+ src
+ second
+ (make-primcall #f 'apply
+ (list
+ (make-primitive-ref #f 'values)
+ (make-lexical-ref #f 'vals vals))))
+ #f))))
+
;; ORIG has been alpha-renamed to NEW. Analyze NEW and record a link
;; from it to ORIG.
;;
(else
(residualize-call))))
- (define (inline-values exp src names gensyms body)
+ (define (inline-values src exp nmin nmax consumer)
(let loop ((exp exp))
(match exp
;; Some expression types are always singly-valued.
($ <toplevel-ref>)
($ <module-ref>)
($ <primitive-ref>)
- ($ <dynref>)
($ <lexical-set>) ; FIXME: these set! expressions
($ <toplevel-set>) ; could return zero values in
($ <toplevel-define>) ; the future
($ <module-set>) ;
- ($ <dynset>)) ;
- (and (= (length names) 1)
- (make-let src names gensyms (list exp) body)))
- (($ <primcall> src (? singly-valued-primitive? name))
- (and (= (length names) 1)
- (make-let src names gensyms (list exp) body)))
+ ($ <primcall> src (? singly-valued-primitive?)))
+ (and (<= nmin 1) (or (not nmax) (>= nmax 1))
+ (make-call src (make-lambda #f '() consumer) (list exp))))
;; Statically-known number of values.
(($ <primcall> src 'values vals)
- (and (= (length names) (length vals))
- (make-let src names gensyms vals body)))
+ (and (<= nmin (length vals)) (or (not nmax) (>= nmax (length vals)))
+ (make-call src (make-lambda #f '() consumer) vals)))
;; Not going to copy code into both branches.
(($ <conditional>) #f)
(make-let-values src exp
(make-lambda-case src2 req opt rest kw
inits gensyms body #f)))))
- (($ <dynwind> src winder pre body post unwinder)
- (let ((body (loop body)))
- (and body
- (make-dynwind src winder pre body post unwinder))))
- (($ <dynlet> src fluids vals body)
- (let ((body (loop body)))
- (and body
- (make-dynlet src fluids vals body))))
(($ <seq> src head tail)
(let ((tail (loop tail)))
(and tail (make-seq src head tail)))))))
(define (small-expression? x limit)
(let/ec k
(tree-il-fold
- (lambda (x res) ; leaf
- (1+ res))
(lambda (x res) ; down
(1+ res))
(lambda (x res) ; up
((vhash-assq var env) => cdr)
(else (error "unbound var" var))))
+ ;; Find a value referenced a specific number of times. This is a hack
+ ;; that's used for propagating fresh data structures like rest lists and
+ ;; prompt tags. Usually we wouldn't copy consed data, but we can do so in
+ ;; some special cases like `apply' or prompts if we can account
+ ;; for all of its uses.
+ ;;
+ ;; You don't want to use this in general because it introduces a slight
+ ;; nonlinearity by running peval again (though with a small effort and size
+ ;; counter).
+ ;;
+ (define (find-definition x n-aliases)
+ (cond
+ ((lexical-ref? x)
+ (cond
+ ((lookup (lexical-ref-gensym x))
+ => (lambda (op)
+ (if (var-set? (operand-var op))
+ (values #f #f)
+ (let ((y (or (operand-residual-value op)
+ (visit-operand op counter 'value 10 10)
+ (operand-source op))))
+ (cond
+ ((and (lexical-ref? y)
+ (= (lexical-refcount (lexical-ref-gensym x)) 1))
+ ;; X is a simple alias for Y. Recurse, regardless of
+ ;; the number of aliases we were expecting.
+ (find-definition y n-aliases))
+ ((= (lexical-refcount (lexical-ref-gensym x)) n-aliases)
+ ;; We found a definition that is aliased the right
+ ;; number of times. We still recurse in case it is a
+ ;; lexical.
+ (values (find-definition y 1)
+ op))
+ (else
+ ;; We can't account for our aliases.
+ (values #f #f)))))))
+ (else
+ ;; A formal parameter. Can't say anything about that.
+ (values #f #f))))
+ ((= n-aliases 1)
+ ;; Not a lexical: success, but only if we are looking for an
+ ;; unaliased value.
+ (values x #f))
+ (else (values #f #f))))
+
(define (visit exp ctx)
(loop exp env counter ctx))
(begin
(record-operand-use op)
(make-lexical-set src name (operand-sym op) (for-value exp))))))
+ (($ <let> src
+ (names ... rest)
+ (gensyms ... rest-sym)
+ (vals ... ($ <primcall> _ 'list rest-args))
+ ($ <primcall> asrc 'apply
+ (proc args ...
+ ($ <lexical-ref> _
+ (? (cut eq? <> rest))
+ (? (lambda (sym)
+ (and (eq? sym rest-sym)
+ (= (lexical-refcount sym) 1))))))))
+ (let* ((tmps (make-list (length rest-args) 'tmp))
+ (tmp-syms (fresh-temporaries tmps)))
+ (for-tail
+ (make-let src
+ (append names tmps)
+ (append gensyms tmp-syms)
+ (append vals rest-args)
+ (make-call
+ asrc
+ proc
+ (append args
+ (map (cut make-lexical-ref #f <> <>)
+ tmps tmp-syms)))))))
(($ <let> src names gensyms vals body)
(define (compute-alias exp)
;; It's very common for macros to introduce something like:
;; reconstruct the let-values, pevaling the consumer.
(let ((producer (for-values producer)))
(or (match consumer
- (($ <lambda-case> src req #f #f #f () gensyms body #f)
- (cond
- ((inline-values producer src req gensyms body)
- => for-tail)
- (else #f)))
+ (($ <lambda-case> src (req-name) #f #f #f () (req-sym) body #f)
+ (for-tail
+ (make-let src (list req-name) (list req-sym) (list producer)
+ body)))
+ ((and ($ <lambda-case> src () #f rest #f () (rest-sym) body #f)
+ (? (lambda _ (singly-valued-expression? producer))))
+ (let ((tmp (gensym "tmp ")))
+ (record-new-temporary! 'tmp tmp 1)
+ (for-tail
+ (make-let
+ src (list 'tmp) (list tmp) (list producer)
+ (make-let
+ src (list rest) (list rest-sym)
+ (list
+ (make-primcall #f 'list
+ (list (make-lexical-ref #f 'tmp tmp))))
+ body)))))
+ (($ <lambda-case> src req opt rest #f inits gensyms body #f)
+ (let* ((nmin (length req))
+ (nmax (and (not rest) (+ nmin (if opt (length opt) 0)))))
+ (cond
+ ((inline-values lv-src producer nmin nmax consumer)
+ => for-tail)
+ (else #f))))
(_ #f))
(make-let-values lv-src producer (for-tail consumer)))))
- (($ <dynwind> src winder pre body post unwinder)
- (make-dynwind src (for-value winder) (for-effect pre)
- (for-tail body)
- (for-effect post) (for-value unwinder)))
- (($ <dynlet> src fluids vals body)
- (make-dynlet src (map for-value fluids) (map for-value vals)
- (for-tail body)))
- (($ <dynref> src fluid)
- (make-dynref src (for-value fluid)))
- (($ <dynset> src fluid exp)
- (make-dynset src (for-value fluid) (for-value exp)))
(($ <toplevel-ref> src (? effect-free-primitive? name))
exp)
(($ <toplevel-ref>)
(simplify-conditional
(make-conditional src c (for-tail subsequent)
(for-tail alternate))))))
- (($ <primcall> src '@call-with-values
+ (($ <primcall> src 'call-with-values
(producer
($ <lambda> _ _
(and consumer
consumer)))
(($ <primcall> src 'dynamic-wind (w thunk u))
(for-tail
- (cond
- ((not (constant-expression? w))
- (cond
- ((not (constant-expression? u))
- (let ((w-sym (gensym "w ")) (u-sym (gensym "u ")))
- (record-new-temporary! 'w w-sym 2)
- (record-new-temporary! 'u u-sym 2)
- (make-let src '(w u) (list w-sym u-sym) (list w u)
- (make-dynwind
- src
- (make-lexical-ref #f 'w w-sym)
- (make-call #f (make-lexical-ref #f 'w w-sym) '())
- (make-call #f thunk '())
- (make-call #f (make-lexical-ref #f 'u u-sym) '())
- (make-lexical-ref #f 'u u-sym)))))
- (else
- (let ((w-sym (gensym "w ")))
- (record-new-temporary! 'w w-sym 2)
- (make-let src '(w) (list w-sym) (list w)
- (make-dynwind
- src
- (make-lexical-ref #f 'w w-sym)
- (make-call #f (make-lexical-ref #f 'w w-sym) '())
- (make-call #f thunk '())
- (make-call #f u '())
- u))))))
- ((not (constant-expression? u))
- (let ((u-sym (gensym "u ")))
- (record-new-temporary! 'u u-sym 2)
- (make-let src '(u) (list u-sym) (list u)
- (make-dynwind
- src
- w
- (make-call #f w '())
- (make-call #f thunk '())
- (make-call #f (make-lexical-ref #f 'u u-sym) '())
- (make-lexical-ref #f 'u u-sym)))))
- (else
- (make-dynwind src w (make-call #f w '()) (make-call #f thunk '())
- (make-call #f u '()) u)))))
+ (with-temporaries
+ src (list w u) 2 constant-expression?
+ (match-lambda
+ ((w u)
+ (make-seq
+ src
+ (make-seq
+ src
+ (make-conditional
+ src
+ ;; fixme: introduce logic to fold thunk?
+ (make-primcall src 'thunk? (list u))
+ (make-call src w '())
+ (make-primcall
+ src 'scm-error
+ (list
+ (make-const #f 'wrong-type-arg)
+ (make-const #f "dynamic-wind")
+ (make-const #f "Wrong type (expecting thunk): ~S")
+ (make-primcall #f 'list (list u))
+ (make-primcall #f 'list (list u)))))
+ (make-primcall src 'wind (list w u)))
+ (make-begin0 src
+ (make-call src thunk '())
+ (make-seq src
+ (make-primcall src 'unwind '())
+ (make-call src u '())))))))))
+
+ (($ <primcall> src 'with-fluid* (f v thunk))
+ (for-tail
+ (with-temporaries
+ src (list f v thunk) 1 constant-expression?
+ (match-lambda
+ ((f v thunk)
+ (make-seq src
+ (make-primcall src 'push-fluid (list f v))
+ (make-begin0 src
+ (make-call src thunk '())
+ (make-primcall src 'pop-fluid '()))))))))
(($ <primcall> src 'values exps)
(cond
(for-tail (list->seq src (append (cdr vals) (list (car vals)))))
(make-primcall src 'values vals))))))
- (($ <primcall> src (or 'apply '@apply) (proc args ... tail))
- (match (for-value tail)
- (($ <const> _ (args* ...))
- (let ((args* (map (lambda (x) (make-const #f x)) args*)))
- (for-tail (make-call src proc (append args args*)))))
- (($ <primcall> _ 'list args*)
- (for-tail (make-call src proc (append args args*))))
- (tail
- (let ((args (append (map for-value args) (list tail))))
- (make-primcall src '@apply (cons (for-value proc) args))))))
+ (($ <primcall> src 'apply (proc args ... tail))
+ (let lp ((tail* (find-definition tail 1)) (speculative? #t))
+ (define (copyable? x)
+ ;; Inlining a result from find-definition effectively copies it,
+ ;; relying on the let-pruning to remove its original binding. We
+ ;; shouldn't copy non-constant expressions.
+ (or (not speculative?) (constant-expression? x)))
+ (match tail*
+ (($ <const> _ (args* ...))
+ (let ((args* (map (cut make-const #f <>) args*)))
+ (for-tail (make-call src proc (append args args*)))))
+ (($ <primcall> _ 'cons
+ ((and head (? copyable?)) (and tail (? copyable?))))
+ (for-tail (make-primcall src 'apply
+ (cons proc
+ (append args (list head tail))))))
+ (($ <primcall> _ 'list
+ (and args* ((? copyable?) ...)))
+ (for-tail (make-call src proc (append args args*))))
+ (tail*
+ (if speculative?
+ (lp (for-value tail) #f)
+ (let ((args (append (map for-value args) (list tail*))))
+ (make-primcall src 'apply
+ (cons (for-value proc) args))))))))
(($ <primcall> src (? constructor-primitive? name) args)
(cond
((name . args)
(make-primcall src name args))))))
- (($ <primcall> src (? accessor-primitive? name) args)
+ (($ <primcall> src 'thunk? (proc))
+ (case ctx
+ ((effect)
+ (for-tail (make-seq src proc (make-void src))))
+ (else
+ (match (for-value proc)
+ (($ <lambda> _ _ ($ <lambda-case> _ req))
+ (for-tail (make-const src (null? req))))
+ (proc
+ (match (find-definition proc 2)
+ (($ <lambda> _ _ ($ <lambda-case> _ req))
+ (for-tail (make-const src (null? req))))
+ (_
+ (make-primcall src 'thunk? (list proc)))))))))
+
+ (($ <primcall> src name args)
(match (cons name (map for-value args))
;; FIXME: these for-tail recursions could take place outside
;; an effort counter.
(for-tail (make-seq src k (make-const #f #f))))
(else
(make-primcall src name (list k (make-const #f elts))))))))
- ((name . args)
- (fold-constants src name args ctx))))
-
- (($ <primcall> src (? equality-primitive? name) (a b))
- (let ((val-a (for-value a))
- (val-b (for-value b)))
- (log 'equality-primitive name val-a val-b)
- (cond ((and (lexical-ref? val-a) (lexical-ref? val-b)
- (eq? (lexical-ref-gensym val-a)
- (lexical-ref-gensym val-b)))
- (for-tail (make-const #f #t)))
- (else
- (fold-constants src name (list val-a val-b) ctx)))))
-
- (($ <primcall> src (? effect-free-primitive? name) args)
- (fold-constants src name (map for-value args) ctx))
+ (((? equality-primitive?)
+ ($ <lexical-ref> _ _ sym) ($ <lexical-ref> _ _ sym))
+ (for-tail (make-const #f #t)))
- (($ <primcall> src name args)
- (make-primcall src name (map for-value args)))
+ (((? effect-free-primitive?) . args)
+ (fold-constants src name args ctx))
+
+ ((name . args)
+ (make-primcall src name args))))
(($ <call> src orig-proc orig-args)
;; todo: augment the global env with specialized functions
- (let ((proc (visit orig-proc 'operator)))
+ (let revisit-proc ((proc (visit orig-proc 'operator)))
(match proc
(($ <primitive-ref> _ name)
(for-tail (make-primcall src name orig-args)))
(($ <lambda> _ _
- ($ <lambda-case> _ req opt #f #f inits gensyms body #f))
- ;; Simple case: no rest, no keyword arguments.
+ ($ <lambda-case> _ req opt rest #f inits gensyms body #f))
+ ;; Simple case: no keyword arguments.
;; todo: handle the more complex cases
(let* ((nargs (length orig-args))
(nreq (length req))
- (nopt (if opt (length opt) 0))
+ (opt (or opt '()))
+ (rest (if rest (list rest) '()))
+ (nopt (length opt))
(key (source-expression proc)))
+ (define (inlined-call)
+ (let ((req-vals (list-head orig-args nreq))
+ (opt-vals (let lp ((args (drop orig-args nreq))
+ (inits inits)
+ (out '()))
+ (match inits
+ (() (reverse out))
+ ((init . inits)
+ (match args
+ (()
+ (lp '() inits (cons init out)))
+ ((arg . args)
+ (lp args inits (cons arg out))))))))
+ (rest-vals (cond
+ ((> nargs (+ nreq nopt))
+ (list (make-primcall
+ #f 'list
+ (drop orig-args (+ nreq nopt)))))
+ (rest (list (make-const #f '())))
+ (else '()))))
+ (if (>= nargs (+ nreq nopt))
+ (make-let src
+ (append req opt rest)
+ gensyms
+ (append req-vals opt-vals rest-vals)
+ body)
+ ;; The required argument values are in the scope
+ ;; of the optional argument initializers.
+ (make-let src
+ (append req rest)
+ (append (list-head gensyms nreq)
+ (last-pair gensyms))
+ (append req-vals rest-vals)
+ (make-let src
+ opt
+ (list-head (drop gensyms nreq) nopt)
+ opt-vals
+ body)))))
+
(cond
- ((or (< nargs nreq) (> nargs (+ nreq nopt)))
+ ((or (< nargs nreq) (and (not rest) (> nargs (+ nreq nopt))))
;; An error, or effecting arguments.
(make-call src (for-call orig-proc) (map for-value orig-args)))
((or (and=> (find-counter key counter) counter-recursive?)
(lp (counter-prev counter)))))))
(log 'inline-recurse key)
- (loop (make-let src (append req (or opt '()))
- gensyms
- (append orig-args
- (drop inits (- nargs nreq)))
- body)
- env counter ctx))
+ (loop (inlined-call) env counter ctx))
(else
;; An integration at the top-level, the first
;; recursion of a recursive procedure, or a nested
(make-top-counter effort-limit operand-size-limit
abort key))))
(define result
- (loop (make-let src (append req (or opt '()))
- gensyms
- (append orig-args
- (drop inits (- nargs nreq)))
- body)
- env new-counter ctx))
+ (loop (inlined-call) env new-counter ctx))
(if counter
;; The nested inlining attempt succeeded.
(log 'inline-end result exp)
result)))))
+ (($ <let> _ _ _ vals _)
+ ;; Attempt to inline `let' in the operator position.
+ ;;
+ ;; We have to re-visit the proc in value mode, since the
+ ;; `let' bindings might have been introduced or renamed,
+ ;; whereas the lambda (if any) in operator position has not
+ ;; been renamed.
+ (if (or (and-map constant-expression? vals)
+ (and-map constant-expression? orig-args))
+ ;; The arguments and the let-bound values commute.
+ (match (for-value orig-proc)
+ (($ <let> lsrc names syms vals body)
+ (log 'inline-let orig-proc)
+ (for-tail
+ (make-let lsrc names syms vals
+ (make-call src body orig-args))))
+ ;; It's possible for a `let' to go away after the
+ ;; visit due to the fact that visiting a procedure in
+ ;; value context will prune unused bindings, whereas
+ ;; visiting in operator mode can't because it doesn't
+ ;; traverse through lambdas. In that case re-visit
+ ;; the procedure.
+ (proc (revisit-proc proc)))
+ (make-call src (for-call orig-proc)
+ (map for-value orig-args))))
(_
(make-call src (for-call orig-proc) (map for-value orig-args))))))
(($ <lambda> src meta body)
((operator) exp)
(else (record-source-expression!
exp
- (make-lambda src meta (for-values body))))))
+ (make-lambda src meta (and body (for-values body)))))))
(($ <lambda-case> src req opt rest kw inits gensyms body alt)
(define (lift-applied-lambda body gensyms)
(and (not opt) rest (not kw)
(match body
- (($ <primcall> _ '@apply
- (($ <lambda> _ _ lcase)
+ (($ <primcall> _ 'apply
+ (($ <lambda> _ _ (and lcase ($ <lambda-case>)))
($ <lexical-ref> _ _ sym)
...))
(and (equal? sym gensyms)
(seq-head head)
head)
tail))))
- (($ <prompt> src tag body handler)
+ (($ <prompt> src escape-only? tag body handler)
(define (make-prompt-tag? x)
(match x
(($ <primcall> _ 'make-prompt-tag (or () ((? constant-expression?))))
#t)
(_ #f)))
- (define (find-definition x n-aliases)
- (cond
- ((lexical-ref? x)
- (cond
- ((lookup (lexical-ref-gensym x))
- => (lambda (op)
- (let ((y (or (operand-residual-value op)
- (visit-operand op counter 'value 10 10))))
- (cond
- ((and (lexical-ref? y)
- (= (lexical-refcount (lexical-ref-gensym x)) 1))
- ;; X is a simple alias for Y. Recurse, regardless of
- ;; the number of aliases we were expecting.
- (find-definition y n-aliases))
- ((= (lexical-refcount (lexical-ref-gensym x)) n-aliases)
- ;; We found a definition that is aliased the right
- ;; number of times. We still recurse in case it is a
- ;; lexical.
- (values (find-definition y 1)
- op))
- (else
- ;; We can't account for our aliases.
- (values #f #f))))))
- (else
- ;; A formal parameter. Can't say anything about that.
- (values #f #f))))
- ((= n-aliases 1)
- ;; Not a lexical: success, but only if we are looking for an
- ;; unaliased value.
- (values x #f))
- (else (values #f #f))))
(let ((tag (for-value tag))
- (body (for-tail body)))
+ (body (if escape-only? (for-tail body) (for-value body))))
(cond
((find-definition tag 1)
(lambda (val op)
;; for this <prompt>, so we can elide the <prompt>
;; entirely.
(unrecord-operand-uses op 1)
- body))
- ((find-definition tag 2)
- (lambda (val op)
- (and (make-prompt-tag? val)
- (abort? body)
- (tree-il=? (abort-tag body) tag)))
- => (lambda (val op)
- ;; (let ((t (make-prompt-tag)))
- ;; (call-with-prompt t
- ;; (lambda () (abort-to-prompt t val ...))
- ;; (lambda (k arg ...) e ...)))
- ;; => (let-values (((k arg ...) (values values val ...)))
- ;; e ...)
- (unrecord-operand-uses op 2)
- (for-tail
- (make-let-values
- src
- (make-primcall #f 'apply
- `(,(make-primitive-ref #f 'values)
- ,(make-primitive-ref #f 'values)
- ,@(abort-args body)
- ,(abort-tail body)))
- (for-value handler)))))
+ (for-tail (if escape-only? body (make-call src body '())))))
(else
- (make-prompt src tag body (for-value handler))))))
+ (let ((handler (for-value handler)))
+ (define (escape-only-handler? handler)
+ (match handler
+ (($ <lambda> _ _
+ ($ <lambda-case> _ (_ . _) _ _ _ _ (k . _) body #f))
+ (not (tree-il-any
+ (match-lambda
+ (($ <lexical-ref> _ _ (? (cut eq? <> k))) #t)
+ (_ #f))
+ body)))
+ (else #f)))
+ (if (and (not escape-only?) (escape-only-handler? handler))
+ ;; Prompt transitioning to escape-only; transition body
+ ;; to be an expression.
+ (for-tail
+ (make-prompt src #t tag (make-call #f body '()) handler))
+ (make-prompt src escape-only? tag body handler)))))))
+
(($ <abort> src tag args tail)
(make-abort src (for-value tag) (map for-value args)
(for-value tail))))))
HCoop / bpt / guile.git / blobdiff