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fix related to continuations

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Check that it works to apply a continuation that shares with
an enclosing continuation, where a runstack overflow happens
between the continuations.

Closes PR 15281
This commit is contained in:
Matthew Flatt 2016-04-04 11:19:11 -06:00
parent 09313a0942
commit ffbdc4b61c
2 changed files with 43 additions and 3 deletions
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36
pkgs/racket-test-core/tests/racket/prompt.rktl
View File

@ -464,6 +464,42 @@
;; let's check that 3/4 were collected:
(test #t < (hash-count ht) (* 1/4 (length l)))))
;;----------------------------------------
;; Check that it works to apply a continuation that shares with
;; an enclosing continuation, where a runstack overflow happens
;; between the continuations
(let ()
(define N 100)
(define N2 10)
(define M 10)
(define p (make-continuation-prompt-tag))
(define (grab n m k-prev q)
(cond
[(positive? n)
(let ([x (grab (sub1 n) m k-prev q)])
(lambda () x))]
[(positive? m)
((call/cc
(lambda (k)
(grab N2 (sub1 m) k q))
p))]
[(positive? q)
(call-with-continuation-prompt
(lambda ()
(k-prev
(lambda ()
(grab N M void (sub1 q)))))
p)]
[else void]))
(call-with-continuation-prompt
(lambda ()
(grab N M void 10))
p))
;;----------------------------------------
(report-errs)

10
racket/src/racket/src/fun.c
View File

@ -4793,6 +4793,8 @@ static Scheme_Saved_Stack *copy_out_runstack(Scheme_Thread *p,
size = p->runstack_size - (runstack XFORM_OK_MINUS runstack_start);
}
MZ_ASSERT(size <= p->runstack_size);
saved->runstack_size = size;
start = MALLOC_N(Scheme_Object*, size);
saved->runstack_start = start;
@ -5934,11 +5936,12 @@ static void restore_continuation(Scheme_Cont *cont, Scheme_Thread *p, int for_pr
Scheme_Cont *rs_cont = cont;
Scheme_Saved_Stack *saved, *actual;
int delta = 0;
while (rs_cont->buf_ptr->buf.cont) {
while (rs_cont->buf_ptr->buf.cont
&& (rs_cont->buf_ptr->buf.cont->runstack_start == cont->runstack_start)) {
delta += rs_cont->runstack_copied->runstack_size;
rs_cont = rs_cont->buf_ptr->buf.cont;
if (rs_cont->runstack_copied->runstack_size) {
delta -= 1; /* overlap for not-saved call/cc argument */
if (rs_cont->runstack_copied->runstack_size > MAX_CALL_CC_ARG_COUNT) {
delta -= MAX_CALL_CC_ARG_COUNT; /* overlap for not-saved call/cc argument */
}
}
actual = NULL;
@ -5954,6 +5957,7 @@ static void restore_continuation(Scheme_Cont *cont, Scheme_Thread *p, int for_pr
} else {
meta_prompt->runstack_boundary_start = MZ_RUNSTACK_START;
meta_prompt->runstack_boundary_offset = (MZ_RUNSTACK - MZ_RUNSTACK_START) + saved->runstack_size + delta;
MZ_ASSERT(meta_prompt->runstack_boundary_offset <= scheme_current_thread->runstack_size);
}
}