1 ;;; TREE-IL -> GLIL compiler
3 ;; Copyright (C) 2001,2008,2009,2010 Free Software Foundation, Inc.
5 ;;;; This library is free software; you can redistribute it and/or
6 ;;;; modify it under the terms of the GNU Lesser General Public
7 ;;;; License as published by the Free Software Foundation; either
8 ;;;; version 3 of the License, or (at your option) any later version.
10 ;;;; This library is distributed in the hope that it will be useful,
11 ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
12 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 ;;;; Lesser General Public License for more details.
15 ;;;; You should have received a copy of the GNU Lesser General Public
16 ;;;; License along with this library; if not, write to the Free Software
17 ;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 (define-module (language tree-il analyze)
22 #:use-module (srfi srfi-1)
23 #:use-module (srfi srfi-9)
24 #:use-module (srfi srfi-11)
25 #:use-module (ice-9 vlist)
26 #:use-module (system base syntax)
27 #:use-module (system base message)
28 #:use-module (system vm program)
29 #:use-module (language tree-il)
30 #:use-module (system base pmatch)
31 #:export (analyze-lexicals
33 unused-variable-analysis
34 unused-toplevel-analysis
35 unbound-variable-analysis
38 ;; Allocation is the process of assigning storage locations for lexical
39 ;; variables. A lexical variable has a distinct "address", or storage
40 ;; location, for each procedure in which it is referenced.
42 ;; A variable is "local", i.e., allocated on the stack, if it is
43 ;; referenced from within the procedure that defined it. Otherwise it is
44 ;; a "closure" variable. For example:
46 ;; (lambda (a) a) ; a will be local
47 ;; `a' is local to the procedure.
49 ;; (lambda (a) (lambda () a))
50 ;; `a' is local to the outer procedure, but a closure variable with
51 ;; respect to the inner procedure.
53 ;; If a variable is ever assigned, it needs to be heap-allocated
54 ;; ("boxed"). This is so that closures and continuations capture the
55 ;; variable's identity, not just one of the values it may have over the
56 ;; course of program execution. If the variable is never assigned, there
57 ;; is no distinction between value and identity, so closing over its
58 ;; identity (whether through closures or continuations) can make a copy
59 ;; of its value instead.
61 ;; Local variables are stored on the stack within a procedure's call
62 ;; frame. Their index into the stack is determined from their linear
63 ;; postion within a procedure's binding path:
70 ;; This algorithm has the problem that variables are only allocated
71 ;; indices at the end of the binding path. If variables bound early in
72 ;; the path are not used in later portions of the path, their indices
73 ;; will not be recycled. This problem is particularly egregious in the
77 ;; -> (let ((a x)) (if a a (let ((b y)) (if b b z))))
79 ;; As you can see, the `a' binding is only used in the ephemeral
80 ;; `consequent' clause of the first `if', but its index would be
81 ;; reserved for the whole of the `or' expansion. So we have a hack for
82 ;; this specific case. A proper solution would be some sort of liveness
83 ;; analysis, and not our linear allocation algorithm.
85 ;; Closure variables are captured when a closure is created, and stored in a
86 ;; vector inline to the closure object itself. Each closure variable has a
87 ;; unique index into that vector.
89 ;; There is one more complication. Procedures bound by <fix> may, in
90 ;; some cases, be rendered inline to their parent procedure. That is to
93 ;; (letrec ((lp (lambda () (lp)))) (lp))
94 ;; => (fix ((lp (lambda () (lp)))) (lp))
95 ;; => goto FIX-BODY; LP: goto LP; FIX-BODY: goto LP;
96 ;; ^ jump over the loop ^ the fixpoint lp ^ starting off the loop
98 ;; The upshot is that we don't have to allocate any space for the `lp'
99 ;; closure at all, as it can be rendered inline as a loop. So there is
100 ;; another kind of allocation, "label allocation", in which the
101 ;; procedure is simply a label, placed at the start of the lambda body.
102 ;; The label is the gensym under which the lambda expression is bound.
104 ;; The analyzer checks to see that the label is called with the correct
105 ;; number of arguments. Calls to labels compile to rename + goto.
106 ;; Lambda, the ultimate goto!
109 ;; The return value of `analyze-lexicals' is a hash table, the
112 ;; The allocation maps gensyms -- recall that each lexically bound
113 ;; variable has a unique gensym -- to storage locations ("addresses").
114 ;; Since one gensym may have many storage locations, if it is referenced
115 ;; in many procedures, it is a two-level map.
117 ;; The allocation also stored information on how many local variables
118 ;; need to be allocated for each procedure, lexicals that have been
119 ;; translated into labels, and information on what free variables to
120 ;; capture from its lexical parent procedure.
122 ;; In addition, we have a conflation: while we're traversing the code,
123 ;; recording information to pass to the compiler, we take the
124 ;; opportunity to generate labels for each lambda-case clause, so that
125 ;; generated code can skip argument checks at runtime if they match at
128 ;; Also, while we're a-traversing and an-allocating, we check prompt
129 ;; handlers to see if the "continuation" argument is used. If not, we
130 ;; mark the prompt as being "escape-only". This allows us to implement
131 ;; `catch' and `throw' using `prompt' and `control', but without causing
132 ;; a continuation to be reified. Heh heh.
136 ;; sym -> {lambda -> address}
137 ;; lambda -> (labels . free-locs)
138 ;; lambda-case -> (gensym . nlocs)
139 ;; prompt -> escape-only?
141 ;; address ::= (local? boxed? . index)
142 ;; labels ::= ((sym . lambda) ...)
143 ;; free-locs ::= ((sym0 . address0) (sym1 . address1) ...)
144 ;; free variable addresses are relative to parent proc.
146 (define (make-hashq k v)
147 (let ((res (make-hash-table)))
151 (define (analyze-lexicals x)
152 ;; bound-vars: lambda -> (sym ...)
153 ;; all identifiers bound within a lambda
154 (define bound-vars (make-hash-table))
155 ;; free-vars: lambda -> (sym ...)
156 ;; all identifiers referenced in a lambda, but not bound
157 ;; NB, this includes identifiers referenced by contained lambdas
158 (define free-vars (make-hash-table))
159 ;; assigned: sym -> #t
160 ;; variables that are assigned
161 (define assigned (make-hash-table))
162 ;; refcounts: sym -> count
163 ;; allows us to detect the or-expansion in O(1) time
164 (define refcounts (make-hash-table))
165 ;; labels: sym -> lambda
166 ;; for determining if fixed-point procedures can be rendered as
168 (define labels (make-hash-table))
170 ;; returns variables referenced in expr
171 (define (analyze! x proc labels-in-proc tail? tail-call-args)
172 (define (step y) (analyze! y proc labels-in-proc #f #f))
173 (define (step-tail y) (analyze! y proc labels-in-proc tail? #f))
174 (define (step-tail-call y args) (analyze! y proc labels-in-proc #f
176 (define (recur/labels x new-proc labels)
177 (analyze! x new-proc (append labels labels-in-proc) #t #f))
178 (define (recur x new-proc) (analyze! x new-proc '() tail? #f))
180 ((<application> proc args)
181 (apply lset-union eq? (step-tail-call proc args)
184 ((<conditional> test consequent alternate)
185 (lset-union eq? (step test) (step-tail consequent) (step-tail alternate)))
187 ((<lexical-ref> gensym)
188 (hashq-set! refcounts gensym (1+ (hashq-ref refcounts gensym 0)))
189 (if (not (and tail-call-args
190 (memq gensym labels-in-proc)
191 (let ((p (hashq-ref labels gensym)))
193 (let lp ((c (lambda-body p)))
194 (and c (lambda-case? c)
196 ;; for now prohibit optional &
197 ;; keyword arguments; can relax this
199 (and (= (length (lambda-case-req c))
200 (length tail-call-args))
201 (not (lambda-case-opt c))
202 (not (lambda-case-kw c))
203 (not (lambda-case-rest c)))
204 (lp (lambda-case-alternate c)))))))))
205 (hashq-set! labels gensym #f))
208 ((<lexical-set> gensym exp)
209 (hashq-set! assigned gensym #t)
210 (hashq-set! labels gensym #f)
211 (lset-adjoin eq? (step exp) gensym))
216 ((<toplevel-set> exp)
219 ((<toplevel-define> exp)
223 (let lp ((exps exps) (ret '()))
224 (cond ((null? exps) '())
226 (lset-union eq? ret (step-tail (car exps))))
228 (lp (cdr exps) (lset-union eq? ret (step (car exps))))))))
231 ;; order is important here
232 (hashq-set! bound-vars x '())
233 (let ((free (recur body x)))
234 (hashq-set! bound-vars x (reverse! (hashq-ref bound-vars x)))
235 (hashq-set! free-vars x free)
238 ((<lambda-case> opt kw inits vars body alternate)
239 (hashq-set! bound-vars proc
240 (append (reverse vars) (hashq-ref bound-vars proc)))
245 (apply lset-union eq? (map step inits))
248 (if alternate (step-tail alternate) '())))
250 ((<let> vars vals body)
251 (hashq-set! bound-vars proc
252 (append (reverse vars) (hashq-ref bound-vars proc)))
254 (apply lset-union eq? (step-tail body) (map step vals))
257 ((<letrec> vars vals body)
258 (hashq-set! bound-vars proc
259 (append (reverse vars) (hashq-ref bound-vars proc)))
260 (for-each (lambda (sym) (hashq-set! assigned sym #t)) vars)
262 (apply lset-union eq? (step-tail body) (map step vals))
265 ((<fix> vars vals body)
266 ;; Try to allocate these procedures as labels.
267 (for-each (lambda (sym val) (hashq-set! labels sym val))
269 (hashq-set! bound-vars proc
270 (append (reverse vars) (hashq-ref bound-vars proc)))
271 ;; Step into subexpressions.
274 ;; Since we're trying to label-allocate the lambda,
275 ;; pretend it's not a closure, and just recurse into its
276 ;; body directly. (Otherwise, recursing on a closure
277 ;; that references one of the fix's bound vars would
278 ;; prevent label allocation.)
282 ;; just like the closure case, except here we use
283 ;; recur/labels instead of recur
284 (hashq-set! bound-vars x '())
285 (let ((free (recur/labels body x vars)))
286 (hashq-set! bound-vars x (reverse! (hashq-ref bound-vars x)))
287 (hashq-set! free-vars x free)
290 (vars-with-refs (map cons vars var-refs))
291 (body-refs (recur/labels body proc vars)))
292 (define (delabel-dependents! sym)
293 (let ((refs (assq-ref vars-with-refs sym)))
295 (for-each (lambda (sym)
296 (if (hashq-ref labels sym)
298 (hashq-set! labels sym #f)
299 (delabel-dependents! sym))))
301 ;; Stepping into the lambdas and the body might have made some
302 ;; procedures not label-allocatable -- which might have
303 ;; knock-on effects. For example:
304 ;; (fix ((a (lambda () (b)))
305 ;; (b (lambda () a)))
307 ;; As far as `a' is concerned, both `a' and `b' are
308 ;; label-allocatable. But `b' references `a' not in a proc-tail
309 ;; position, which makes `a' not label-allocatable. The
310 ;; knock-on effect is that, when back-propagating this
311 ;; information to `a', `b' will also become not
312 ;; label-allocatable, as it is referenced within `a', which is
313 ;; allocated as a closure. This is a transitive relationship.
314 (for-each (lambda (sym)
315 (if (not (hashq-ref labels sym))
316 (delabel-dependents! sym)))
318 ;; Now lift bound variables with label-allocated lambdas to the
322 (if (hashq-ref labels sym)
323 ;; Remove traces of the label-bound lambda. The free
324 ;; vars will propagate up via the return val.
326 (hashq-set! bound-vars proc
327 (append (hashq-ref bound-vars val)
328 (hashq-ref bound-vars proc)))
329 (hashq-remove! bound-vars val)
330 (hashq-remove! free-vars val))))
333 (apply lset-union eq? body-refs var-refs)
336 ((<let-values> exp body)
337 (lset-union eq? (step exp) (step body)))
339 ((<dynwind> body winder unwinder)
340 (lset-union eq? (step body) (step winder) (step unwinder)))
342 ((<dynlet> fluids vals body)
343 (apply lset-union eq? (step body) (map step (append fluids vals))))
345 ((<prompt> tag body handler)
346 (lset-union eq? (step tag) (step handler)))
349 (apply lset-union eq? (step tag) (map step args)))
353 ;; allocation: sym -> {lambda -> address}
354 ;; lambda -> (nlocs labels . free-locs)
355 (define allocation (make-hash-table))
357 (define (allocate! x proc n)
358 (define (recur y) (allocate! y proc n))
360 ((<application> proc args)
361 (apply max (recur proc) (map recur args)))
363 ((<conditional> test consequent alternate)
364 (max (recur test) (recur consequent) (recur alternate)))
372 ((<toplevel-set> exp)
375 ((<toplevel-define> exp)
379 (apply max (map recur exps)))
382 ;; allocate closure vars in order
383 (let lp ((c (hashq-ref free-vars x)) (n 0))
386 (hashq-set! (hashq-ref allocation (car c))
388 `(#f ,(hashq-ref assigned (car c)) . ,n))
389 (lp (cdr c) (1+ n)))))
391 (let ((nlocs (allocate! body x 0))
394 (hashq-ref (hashq-ref allocation v) proc))
395 (hashq-ref free-vars x)))
398 (cons sym (hashq-ref labels sym)))
399 (hashq-ref bound-vars x)))))
400 ;; set procedure allocations
401 (hashq-set! allocation x (cons labels free-addresses)))
404 ((<lambda-case> opt kw inits vars body alternate)
406 (let lp ((vars vars) (n n))
410 (allocate! body proc n)
411 ;; inits not logically at the end, but they
413 (map (lambda (x) (allocate! x proc n)) inits))))
414 ;; label and nlocs for the case
415 (hashq-set! allocation x (cons (gensym ":LCASE") nlocs))
418 (hashq-set! allocation (car vars)
420 proc `(#t ,(hashq-ref assigned (car vars)) . ,n)))
421 (lp (cdr vars) (1+ n)))))
422 (if alternate (allocate! alternate proc n) n)))
424 ((<let> vars vals body)
425 (let ((nmax (apply max (map recur vals))))
428 ((and (conditional? body)
430 (let ((v (car vars)))
431 (and (not (hashq-ref assigned v))
432 (= (hashq-ref refcounts v 0) 2)
433 (lexical-ref? (conditional-test body))
434 (eq? (lexical-ref-gensym (conditional-test body)) v)
435 (lexical-ref? (conditional-consequent body))
436 (eq? (lexical-ref-gensym (conditional-consequent body)) v))))
437 (hashq-set! allocation (car vars)
438 (make-hashq proc `(#t #f . ,n)))
439 ;; the 1+ for this var
440 (max nmax (1+ n) (allocate! (conditional-alternate body) proc n)))
442 (let lp ((vars vars) (n n))
444 (max nmax (allocate! body proc n))
445 (let ((v (car vars)))
449 `(#t ,(hashq-ref assigned v) . ,n)))
450 (lp (cdr vars) (1+ n)))))))))
452 ((<letrec> vars vals body)
453 (let lp ((vars vars) (n n))
455 (let ((nmax (apply max
457 (allocate! x proc n))
459 (max nmax (allocate! body proc n)))
460 (let ((v (car vars)))
464 `(#t ,(hashq-ref assigned v) . ,n)))
465 (lp (cdr vars) (1+ n))))))
467 ((<fix> vars vals body)
468 (let lp ((in vars) (n n))
470 (let lp ((vars vars) (vals vals) (nmax n))
473 (max nmax (allocate! body proc n)))
474 ((hashq-ref labels (car vars))
475 ;; allocate lambda body inline to proc
478 (record-case (car vals)
480 (max nmax (allocate! body proc n))))))
485 (max nmax (allocate! (car vals) proc n))))))
489 ((hashq-ref assigned v)
490 (error "fixpoint procedures may not be assigned" x))
491 ((hashq-ref labels v)
492 ;; no binding, it's a label
495 ;; allocate closure binding
496 (hashq-set! allocation v (make-hashq proc `(#t #f . ,n)))
497 (lp (cdr in) (1+ n))))))))
499 ((<let-values> exp body)
500 (max (recur exp) (recur body)))
502 ((<dynwind> body winder unwinder)
503 (max (recur body) (recur winder) (recur unwinder)))
505 ((<dynlet> fluids vals body)
506 (apply max (recur body) (map recur (append fluids vals))))
508 ((<prompt> tag body handler)
509 (let ((cont-var (and (lambda-case? handler)
510 (pair? (lambda-case-vars handler))
511 (car (lambda-case-vars handler)))))
512 (hashq-set! allocation x
513 (and cont-var (zero? (hashq-ref refcounts cont-var 0))))
514 (max (recur tag) (recur body) (recur handler))))
517 (apply max (recur tag) (map recur args)))
521 (analyze! x #f '() #t #f)
528 ;;; Tree analyses for warnings.
531 (define-record-type <tree-analysis>
532 (make-tree-analysis leaf down up post init)
534 (leaf tree-analysis-leaf) ;; (lambda (x result env locs) ...)
535 (down tree-analysis-down) ;; (lambda (x result env locs) ...)
536 (up tree-analysis-up) ;; (lambda (x result env locs) ...)
537 (post tree-analysis-post) ;; (lambda (result env) ...)
538 (init tree-analysis-init)) ;; arbitrary value
540 (define (analyze-tree analyses tree env)
541 "Run all tree analyses listed in ANALYSES on TREE for ENV, using
542 `tree-il-fold'. Return TREE. The leaf/down/up procedures of each analysis are
543 passed a ``location stack', which is the stack of `tree-il-src' values for each
544 parent tree (a list); it can be used to approximate source location when
545 accurate information is missing from a given `tree-il' element."
547 (define (traverse proc update-locs)
548 ;; Return a tree traversing procedure that returns a list of analysis
549 ;; results prepended by the location stack.
551 (let ((locs (update-locs x (car results))))
552 (cons locs ;; the location stack
553 (map (lambda (analysis result)
554 ((proc analysis) x result env locs))
558 ;; Keeping/extending/shrinking the location stack.
559 (define (keep-locs x locs) locs)
560 (define (extend-locs x locs) (cons (tree-il-src x) locs))
561 (define (shrink-locs x locs) (cdr locs))
564 (tree-il-fold (traverse tree-analysis-leaf keep-locs)
565 (traverse tree-analysis-down extend-locs)
566 (traverse tree-analysis-up shrink-locs)
567 (cons '() ;; empty location stack
568 (map tree-analysis-init analyses))
571 (for-each (lambda (analysis result)
572 ((tree-analysis-post analysis) result env))
580 ;;; Unused variable analysis.
583 ;; <binding-info> records are used during tree traversals in
584 ;; `unused-variable-analysis'. They contain a list of the local vars
585 ;; currently in scope, and a list of locals vars that have been referenced.
586 (define-record-type <binding-info>
587 (make-binding-info vars refs)
589 (vars binding-info-vars) ;; ((GENSYM NAME LOCATION) ...)
590 (refs binding-info-refs)) ;; (GENSYM ...)
592 (define unused-variable-analysis
593 ;; Report unused variables in the given tree.
595 (lambda (x info env locs)
596 ;; X is a leaf: extend INFO's refs accordingly.
597 (let ((refs (binding-info-refs info))
598 (vars (binding-info-vars info)))
600 ((<lexical-ref> gensym)
601 (make-binding-info vars (vhash-consq gensym #t refs)))
604 (lambda (x info env locs)
605 ;; Going down into X: extend INFO's variable list
607 (let ((refs (binding-info-refs info))
608 (vars (binding-info-vars info))
609 (src (tree-il-src x)))
610 (define (extend inner-vars inner-names)
611 (fold (lambda (var name vars)
612 (vhash-consq var (list name src) vars))
618 ((<lexical-set> gensym)
619 (make-binding-info vars (vhash-consq gensym #t refs)))
620 ((<lambda-case> req opt inits rest kw vars)
623 ,@(if rest (list rest) '())
624 ,@(if kw (map cadr (cdr kw)) '()))))
625 (make-binding-info (extend vars names) refs)))
627 (make-binding-info (extend vars names) refs))
628 ((<letrec> vars names)
629 (make-binding-info (extend vars names) refs))
631 (make-binding-info (extend vars names) refs))
634 (lambda (x info env locs)
635 ;; Leaving X's scope: shrink INFO's variable list
636 ;; accordingly and reported unused nested variables.
637 (let ((refs (binding-info-refs info))
638 (vars (binding-info-vars info)))
639 (define (shrink inner-vars refs)
642 (let ((gensym (car var)))
643 ;; Don't report lambda parameters as unused.
644 (if (and (memq gensym inner-vars)
645 (not (vhash-assq gensym refs))
646 (not (lambda-case? x)))
647 (let ((name (cadr var))
648 ;; We can get approximate source location by going up
649 ;; the LOCS location stack.
652 (warning 'unused-variable loc name)))))
654 (vlist-drop vars (length inner-vars)))
656 ;; For simplicity, we leave REFS untouched, i.e., with
657 ;; names of variables that are now going out of scope.
658 ;; It doesn't hurt as these are unique names, it just
659 ;; makes REFS unnecessarily fat.
661 ((<lambda-case> vars)
662 (make-binding-info (shrink vars refs) refs))
664 (make-binding-info (shrink vars refs) refs))
666 (make-binding-info (shrink vars refs) refs))
668 (make-binding-info (shrink vars refs) refs))
671 (lambda (result env) #t)
672 (make-binding-info vlist-null vlist-null)))
676 ;;; Unused top-level variable analysis.
679 ;; <reference-graph> record top-level definitions that are made, references to
680 ;; top-level definitions and their context (the top-level definition in which
681 ;; the reference appears), as well as the current context (the top-level
682 ;; definition we're currently in). The second part (`refs' below) is
683 ;; effectively a graph from which we can determine unused top-level definitions.
684 (define-record-type <reference-graph>
685 (make-reference-graph refs defs toplevel-context)
687 (defs reference-graph-defs) ;; ((NAME . LOC) ...)
688 (refs reference-graph-refs) ;; ((REF-CONTEXT REF ...) ...)
689 (toplevel-context reference-graph-toplevel-context)) ;; NAME | #f
691 (define (graph-reachable-nodes root refs reachable)
692 ;; Add to REACHABLE the nodes reachable from ROOT in graph REFS. REFS is a
693 ;; vhash mapping nodes to the list of their children: for instance,
694 ;; ((A -> (B C)) (B -> (A)) (C -> ())) corresponds to
703 ;; REACHABLE is a vhash of nodes known to be otherwise reachable.
705 (let loop ((root root)
708 (if (or (vhash-assq root path)
709 (vhash-assq root result))
711 (let* ((children (or (and=> (vhash-assq root refs) cdr) '()))
712 (path (vhash-consq root #t path))
713 (result (fold (lambda (kid result)
714 (loop kid path result))
717 (fold (lambda (kid result)
718 (vhash-consq kid #t result))
722 (define (graph-reachable-nodes* roots refs)
723 ;; Return the list of nodes in REFS reachable from the nodes listed in ROOTS.
724 (vlist-fold (lambda (root+true result)
725 (let* ((root (car root+true))
726 (reachable (graph-reachable-nodes root refs result)))
727 (vhash-consq root #t reachable)))
731 (define (partition* pred vhash)
732 ;; Partition VHASH according to PRED. Return the two resulting vhashes.
734 (vlist-fold (lambda (k+v result)
740 (cons (vhash-consq k v r1) r2)
741 (cons r1 (vhash-consq k v r2)))))
742 (cons vlist-null vlist-null)
744 (values (car result) (cdr result))))
746 (define unused-toplevel-analysis
747 ;; Report unused top-level definitions that are not exported.
748 (let ((add-ref-from-context
750 ;; Add an edge CTX -> NAME in GRAPH.
751 (let* ((refs (reference-graph-refs graph))
752 (defs (reference-graph-defs graph))
753 (ctx (reference-graph-toplevel-context graph))
754 (ctx-refs (or (and=> (vhash-assq ctx refs) cdr) '())))
755 (make-reference-graph (vhash-consq ctx (cons name ctx-refs) refs)
757 (define (macro-variable? name env)
759 (let ((var (module-variable env name)))
760 (and var (variable-bound? var)
761 (macro? (variable-ref var))))))
764 (lambda (x graph env locs)
766 (let ((ctx (reference-graph-toplevel-context graph)))
768 ((<toplevel-ref> name src)
769 (add-ref-from-context graph name))
772 (lambda (x graph env locs)
773 ;; Going down into X.
774 (let ((ctx (reference-graph-toplevel-context graph))
775 (refs (reference-graph-refs graph))
776 (defs (reference-graph-defs graph)))
778 ((<toplevel-define> name src)
780 (defs (vhash-consq name (or src (find pair? locs))
782 (make-reference-graph refs defs name)))
783 ((<toplevel-set> name src)
784 (add-ref-from-context graph name))
787 (lambda (x graph env locs)
788 ;; Leaving X's scope.
791 (let ((refs (reference-graph-refs graph))
792 (defs (reference-graph-defs graph)))
793 (make-reference-graph refs defs #f)))
797 ;; Process the resulting reference graph: determine all private definitions
798 ;; not reachable from any public definition. Macros
799 ;; (syntax-transformers), which are globally bound, never considered
800 ;; unused since we can't tell whether a macro is actually used; in
801 ;; addition, macros are considered roots of the graph since they may use
802 ;; private bindings. FIXME: The `make-syntax-transformer' calls don't
803 ;; contain any literal `toplevel-ref' of the global bindings they use so
804 ;; this strategy fails.
805 (define (exported? name)
807 (module-variable (module-public-interface env) name)
810 (let-values (((public-defs private-defs)
811 (partition* (lambda (name)
813 (macro-variable? name env)))
814 (reference-graph-defs graph))))
815 (let* ((roots (vhash-consq #f #t public-defs))
816 (refs (reference-graph-refs graph))
817 (reachable (graph-reachable-nodes* roots refs))
818 (unused (vlist-filter (lambda (name+src)
819 (not (vhash-assq (car name+src)
822 (vlist-for-each (lambda (name+loc)
823 (let ((name (car name+loc))
824 (loc (cdr name+loc)))
825 (warning 'unused-toplevel loc name)))
828 (make-reference-graph vlist-null vlist-null #f))))
832 ;;; Unbound variable analysis.
835 ;; <toplevel-info> records are used during tree traversal in search of
836 ;; possibly unbound variable. They contain a list of references to
837 ;; potentially unbound top-level variables, and a list of the top-level
838 ;; defines that have been encountered.
839 (define-record-type <toplevel-info>
840 (make-toplevel-info refs defs)
842 (refs toplevel-info-refs) ;; ((VARIABLE-NAME . LOCATION) ...)
843 (defs toplevel-info-defs)) ;; (VARIABLE-NAME ...)
845 (define (goops-toplevel-definition proc args env)
846 ;; If application of PROC to ARGS is a GOOPS top-level definition, return
847 ;; the name of the variable being defined; otherwise return #f. This
848 ;; assumes knowledge of the current implementation of `define-class' et al.
849 (define (toplevel-define-arg args)
850 (and (pair? args) (pair? (cdr args)) (null? (cddr args))
851 (record-case (car args)
853 (and (symbol? exp) exp))
857 ((<module-ref> mod public? name)
858 (and (equal? mod '(oop goops))
860 (eq? name 'toplevel-define!)
861 (toplevel-define-arg args)))
862 ((<toplevel-ref> name)
863 ;; This may be the result of expanding one of the GOOPS macros within
865 (and (eq? name 'toplevel-define!)
866 (eq? env (resolve-module '(oop goops)))
867 (toplevel-define-arg args)))
870 (define unbound-variable-analysis
871 ;; Report possibly unbound variables in the given tree.
873 (lambda (x info env locs)
874 ;; X is a leaf: extend INFO's refs accordingly.
875 (let ((refs (toplevel-info-refs info))
876 (defs (toplevel-info-defs info)))
877 (define (bound? name)
878 (or (and (module? env)
879 (module-variable env name))
880 (vhash-assq name defs)))
883 ((<toplevel-ref> name src)
886 (let ((src (or src (find pair? locs))))
887 (make-toplevel-info (vhash-consq name src refs)
891 (lambda (x info env locs)
892 ;; Going down into X.
893 (let* ((refs (toplevel-info-refs info))
894 (defs (toplevel-info-defs info))
895 (src (tree-il-src x)))
896 (define (bound? name)
897 (or (and (module? env)
898 (module-variable env name))
899 (vhash-assq name defs)))
902 ((<toplevel-set> name src)
904 (make-toplevel-info refs defs)
905 (let ((src (find pair? locs)))
906 (make-toplevel-info (vhash-consq name src refs)
908 ((<toplevel-define> name)
909 (make-toplevel-info (vhash-delete name refs eq?)
910 (vhash-consq name #t defs)))
912 ((<application> proc args)
913 ;; Check for a dynamic top-level definition, as is
914 ;; done by code expanded from GOOPS macros.
915 (let ((name (goops-toplevel-definition proc args
918 (make-toplevel-info (vhash-delete name refs
920 (vhash-consq name #t defs))
921 (make-toplevel-info refs defs))))
923 (make-toplevel-info refs defs)))))
925 (lambda (x info env locs)
926 ;; Leaving X's scope.
929 (lambda (toplevel env)
930 ;; Post-process the result.
931 (vlist-for-each (lambda (name+loc)
932 (let ((name (car name+loc))
933 (loc (cdr name+loc)))
934 (warning 'unbound-variable loc name)))
935 (vlist-reverse (toplevel-info-refs toplevel))))
937 (make-toplevel-info vlist-null vlist-null)))
944 ;; <arity-info> records contain information about lexical definitions of
945 ;; procedures currently in scope, top-level procedure definitions that have
946 ;; been encountered, and calls to top-level procedures that have been
948 (define-record-type <arity-info>
949 (make-arity-info toplevel-calls lexical-lambdas toplevel-lambdas)
951 (toplevel-calls toplevel-procedure-calls) ;; ((NAME . APPLICATION) ...)
952 (lexical-lambdas lexical-lambdas) ;; ((GENSYM . DEFINITION) ...)
953 (toplevel-lambdas toplevel-lambdas)) ;; ((NAME . DEFINITION) ...)
955 (define (validate-arity proc application lexical?)
956 ;; Validate the argument count of APPLICATION, a tree-il application of
957 ;; PROC, emitting a warning in case of argument count mismatch.
959 (define (filter-keyword-args keywords allow-other-keys? args)
960 ;; Filter keyword arguments from ARGS and return the resulting list.
961 ;; KEYWORDS is the list of allowed keywords, and ALLOW-OTHER-KEYS?
962 ;; specified whethere keywords not listed in KEYWORDS are allowed.
963 (let loop ((args args)
967 (let ((arg (car args)))
968 (if (and (const? arg)
969 (or (memq (const-exp arg) keywords)
970 (and allow-other-keys?
971 (keyword? (const-exp arg)))))
972 (loop (if (pair? (cdr args))
977 (cons arg result)))))))
979 (define (arities proc)
980 ;; Return the arities of PROC, which can be either a tree-il or a
983 (or (and (or (null? x) (pair? x))
986 (cond ((program? proc)
987 (values (program-name proc)
989 (list (arity:nreq a) (arity:nopt a) (arity:rest? a)
990 (map car (arity:kw a))
991 (arity:allow-other-keys? a)))
992 (program-arities proc))))
994 (let ((arity (procedure-property proc 'arity)))
995 (values (procedure-name proc)
996 (list (list (car arity) (cadr arity) (caddr arity)
1003 (values name (reverse arities))
1005 ((<lambda-case> req opt rest kw alternate)
1006 (loop name alternate
1007 (cons (list (len req) (len opt) rest
1008 (and (pair? kw) (map car (cdr kw)))
1009 (and (pair? kw) (car kw)))
1011 ((<lambda> meta body)
1012 (loop (assoc-ref meta 'name) body arities))
1014 (values #f #f))))))))
1016 (let ((args (application-args application))
1017 (src (tree-il-src application)))
1018 (call-with-values (lambda () (arities proc))
1019 (lambda (name arities)
1021 (find (lambda (arity)
1023 ((,req ,opt ,rest? ,kw ,aok?)
1024 (let ((args (if (pair? kw)
1025 (filter-keyword-args kw aok? args)
1028 (let ((count (length args)))
1031 (<= count (+ req opt)))))
1037 (warning 'arity-mismatch src
1038 (or name (with-output-to-string (lambda () (write proc))))
1042 (define arity-analysis
1043 ;; Report arity mismatches in the given tree.
1045 (lambda (x info env locs)
1048 (lambda (x info env locs)
1050 (define (extend lexical-name val info)
1051 ;; If VAL is a lambda, add NAME to the lexical-lambdas of INFO.
1052 (let ((toplevel-calls (toplevel-procedure-calls info))
1053 (lexical-lambdas (lexical-lambdas info))
1054 (toplevel-lambdas (toplevel-lambdas info)))
1057 (make-arity-info toplevel-calls
1058 (vhash-consq lexical-name val
1061 ((<lexical-ref> gensym)
1063 (let ((val* (vhash-assq gensym lexical-lambdas)))
1065 (extend lexical-name (cdr val*) info)
1067 ((<toplevel-ref> name)
1069 (make-arity-info toplevel-calls
1070 (vhash-consq lexical-name val
1075 (let ((toplevel-calls (toplevel-procedure-calls info))
1076 (lexical-lambdas (lexical-lambdas info))
1077 (toplevel-lambdas (toplevel-lambdas info)))
1080 ((<toplevel-define> name exp)
1083 (make-arity-info toplevel-calls
1085 (vhash-consq name exp toplevel-lambdas)))
1086 ((<toplevel-ref> name)
1087 ;; alias for another toplevel
1088 (let ((proc (vhash-assq name toplevel-lambdas)))
1089 (make-arity-info toplevel-calls
1091 (vhash-consq (toplevel-define-name x)
1095 toplevel-lambdas))))
1098 (fold extend info vars vals))
1099 ((<letrec> vars vals)
1100 (fold extend info vars vals))
1102 (fold extend info vars vals))
1104 ((<application> proc args src)
1107 (validate-arity proc x #t)
1109 ((<toplevel-ref> name)
1110 (make-arity-info (vhash-consq name x toplevel-calls)
1113 ((<lexical-ref> gensym)
1114 (let ((proc (vhash-assq gensym lexical-lambdas)))
1116 (record-case (cdr proc)
1117 ((<toplevel-ref> name)
1118 ;; alias to toplevel
1119 (make-arity-info (vhash-consq name x toplevel-calls)
1123 (validate-arity (cdr proc) x #t)
1126 ;; If GENSYM wasn't found, it may be because it's an
1127 ;; argument of the procedure being compiled.
1132 (lambda (x info env locs)
1134 (define (shrink name val info)
1135 ;; Remove NAME from the lexical-lambdas of INFO.
1136 (let ((toplevel-calls (toplevel-procedure-calls info))
1137 (lexical-lambdas (lexical-lambdas info))
1138 (toplevel-lambdas (toplevel-lambdas info)))
1139 (make-arity-info toplevel-calls
1140 (if (vhash-assq name lexical-lambdas)
1141 (vlist-tail lexical-lambdas)
1145 (let ((toplevel-calls (toplevel-procedure-calls info))
1146 (lexical-lambdas (lexical-lambdas info))
1147 (toplevel-lambdas (toplevel-lambdas info)))
1150 (fold shrink info vars vals))
1151 ((<letrec> vars vals)
1152 (fold shrink info vars vals))
1154 (fold shrink info vars vals))
1158 (lambda (result env)
1159 ;; Post-processing: check all top-level procedure calls that have been
1161 (let ((toplevel-calls (toplevel-procedure-calls result))
1162 (toplevel-lambdas (toplevel-lambdas result)))
1164 (lambda (name+application)
1165 (let* ((name (car name+application))
1166 (application (cdr name+application))
1168 (or (and=> (vhash-assq name toplevel-lambdas) cdr)
1171 (module-ref env name)))))
1173 ;; handle toplevel aliases
1174 (if (toplevel-ref? proc)
1175 (let ((name (toplevel-ref-name proc)))
1178 (module-ref env name))))
1180 (if (or (lambda? proc*) (procedure? proc*))
1181 (validate-arity proc* application (lambda? proc*)))))
1184 (make-arity-info vlist-null vlist-null vlist-null)))