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rewinding prompts works

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* libguile/control.h (SCM_PROMPT_HANDLER): Remove, it was unused.
  (SCM_PROMPT_DYNWINDS): Rename from SCM_PROMPT_DYNENV.

* libguile/control.c: (scm_c_make_prompt): Take another arg, the winds
  that are to be in place for the prompt. Fix allocation to be 4 words
  instead of 5 (the handler was never used).

* libguile/eval.c (eval):
* libguile/throw.c (pre_init_catch): Adapt to scm_c_make_prompt change.

* libguile/vm-i-system.c (partial-cont-call): Grovel the new elements of
  the wind list in order to call setjmp() on the new prompts. Pass
  cookie to vm_reinstate_partial_continuation.
  (prompt): Adapt to scm_c_make_prompt change.

* libguile/vm.c (vm_reinstate_partial_continuation): Take a cookie arg,
  used when winding captured prompts onto the stack. Winding a prompt
  implies making a new prompt, actually -- with new registers, a new
  jump buffer, new winds, etc.

* test-suite/tests/control.test ("rewinding prompts"): Add a test for
  rewinding prompts.
This commit is contained in:
Andy Wingo 2010-02-26 13:05:25 +01:00
parent 416f26c753
commit adbdfd6d24
7 changed files with 58 additions and 23 deletions
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26
libguile/vm.c
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@ -231,7 +231,7 @@ vm_abort (SCM vm, size_t n, scm_t_int64 vm_cookie)
static void
vm_reinstate_partial_continuation (SCM vm, SCM cont, SCM intwinds,
size_t n, SCM *argv)
size_t n, SCM *argv, scm_t_int64 vm_cookie)
{
struct scm_vm *vp;
struct scm_vm_cont *cp;
@ -267,8 +267,6 @@ vm_reinstate_partial_continuation (SCM vm, SCM cont, SCM intwinds,
vp->fp = RELOC (cp->fp);
vp->ip = cp->mvra;
#undef RELOC
/* now push args. ip is in a MV context. */
for (i = 0; i < n; i++)
{
@ -278,14 +276,32 @@ vm_reinstate_partial_continuation (SCM vm, SCM cont, SCM intwinds,
vp->sp++;
*vp->sp = scm_from_size_t (n);
/* Finally, rewind the dynamic state. */
/* Finally, rewind the dynamic state.
We have to treat prompts specially, because we could be rewinding the
dynamic state from a different thread, or just a different position on the
C and/or VM stack -- so we need to reset the jump buffers so that an abort
comes back here, with appropriately adjusted sp and fp registers. */
{
long delta = 0;
SCM newwinds = scm_i_dynwinds ();
for (; scm_is_pair (intwinds); intwinds = scm_cdr (intwinds), delta--)
newwinds = scm_cons (scm_car (intwinds), newwinds);
{
SCM x = scm_car (intwinds);
if (SCM_PROMPT_P (x))
/* the jmpbuf will be reset by our caller */
x = scm_c_make_prompt (SCM_PROMPT_TAG (x),
RELOC (SCM_PROMPT_REGISTERS (x)->fp),
RELOC (SCM_PROMPT_REGISTERS (x)->sp),
SCM_PROMPT_REGISTERS (x)->ip,
SCM_PROMPT_ESCAPE_P (x),
vm_cookie,
newwinds);
newwinds = scm_cons (x, newwinds);
}
scm_dowinds (newwinds, delta);
}
#undef RELOC
}