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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
Download patch file Download diff file Expand all files Collapse all files

12
libguile/control.c
View file

@ -33,16 +33,15 @@ SCM scm_sys_default_prompt_tag;
SCM
scm_c_make_prompt (SCM k, SCM *fp, SCM *sp, scm_t_uint8 *abort_ip,
scm_t_uint8 escape_only_p, scm_t_int64 vm_cookie)
scm_t_uint8 escape_only_p, scm_t_int64 vm_cookie,
SCM winds)
{
scm_t_bits tag;
SCM ret;
struct scm_prompt_registers *regs;
tag = scm_tc7_prompt;
if (escape_only_p)
tag |= (SCM_F_PROMPT_ESCAPE<<8);
ret = scm_words (tag, 5);
regs = scm_gc_malloc_pointerless (sizeof (*regs), "prompt registers");
regs->fp = fp;
@ -50,11 +49,8 @@ scm_c_make_prompt (SCM k, SCM *fp, SCM *sp, scm_t_uint8 *abort_ip,
regs->ip = abort_ip;
regs->cookie = vm_cookie;
SCM_SET_CELL_OBJECT (ret, 1, k);
SCM_SET_CELL_WORD (ret, 2, (scm_t_bits)regs);
SCM_SET_CELL_OBJECT (ret, 3, scm_i_dynwinds ());
return ret;
return scm_double_cell (tag, SCM_UNPACK (k), (scm_t_bits)regs,
SCM_UNPACK (winds));
}
/* Only to be called if the SCM_PROMPT_SETJMP returns 1 */

6
libguile/control.h
View file

@ -27,8 +27,7 @@
#define SCM_PROMPT_ESCAPE_P(x) (SCM_PROMPT_FLAGS (x) & SCM_F_PROMPT_ESCAPE)
#define SCM_PROMPT_TAG(x) (SCM_CELL_OBJECT ((x), 1))
#define SCM_PROMPT_REGISTERS(x) ((struct scm_prompt_registers*)SCM_CELL_WORD ((x), 2))
#define SCM_PROMPT_DYNENV(x) (SCM_CELL_OBJECT ((x), 3))
#define SCM_PROMPT_HANDLER(x) (SCM_CELL_OBJECT ((x), 4))
#define SCM_PROMPT_DYNWINDS(x) (SCM_CELL_OBJECT ((x), 3))
#define SCM_PROMPT_SETJMP(p) (SCM_I_SETJMP (SCM_PROMPT_REGISTERS (p)->regs))
@ -48,7 +47,8 @@ SCM_INTERNAL SCM scm_sys_default_prompt_tag;
SCM_INTERNAL SCM scm_c_make_prompt (SCM k, SCM *fp, SCM *sp,
scm_t_uint8 *abort_ip,
scm_t_uint8 escape_only_p,
scm_t_int64 vm_cookie);
scm_t_int64 vm_cookie,
SCM winds);
SCM_INTERNAL SCM scm_i_prompt_pop_abort_args_x (SCM prompt);
SCM_INTERNAL void scm_c_abort (SCM vm, SCM tag, size_t n, SCM *argv,

2
libguile/eval.c
View file

@ -432,7 +432,7 @@ eval (SCM x, SCM env)
vm = scm_the_vm ();
prompt = scm_c_make_prompt (eval (CAR (mx), env), SCM_VM_DATA (vm)->fp,
SCM_VM_DATA (vm)->sp, SCM_VM_DATA (vm)->ip,
0, -1);
0, -1, scm_i_dynwinds ());
handler = eval (CDDR (mx), env);
scm_i_set_dynwinds (scm_cons (prompt, scm_i_dynwinds ()));

4
libguile/throw.c
View file

@ -512,8 +512,8 @@ pre_init_catch (SCM tag, SCM thunk, SCM handler, SCM pre_unwind_handler)
vm = scm_the_vm ();
prompt = scm_c_make_prompt (scm_fluid_ref (scm_sys_default_prompt_tag),
SCM_VM_DATA (vm)->fp, SCM_VM_DATA (vm)->sp,
SCM_VM_DATA (vm)->ip, 1, -1);
scm_i_set_dynwinds (scm_cons (prompt, scm_i_dynwinds ()));
SCM_VM_DATA (vm)->ip, 1, -1, scm_i_dynwinds ());
scm_i_set_dynwinds (scm_cons (prompt, SCM_PROMPT_DYNWINDS (prompt)));
if (SCM_PROMPT_SETJMP (prompt))
{

20
libguile/vm-i-system.c
View file

@ -995,7 +995,7 @@ VM_DEFINE_INSTRUCTION (89, continuation_call, "continuation-call", 0, -1, 0)
VM_DEFINE_INSTRUCTION (94, partial_cont_call, "partial-cont-call", 0, -1, 0)
{
SCM vmcont, intwinds;
SCM vmcont, intwinds, prevwinds;
POP (intwinds);
POP (vmcont);
SYNC_REGISTER ();
@ -1003,7 +1003,18 @@ VM_DEFINE_INSTRUCTION (94, partial_cont_call, "partial-cont-call", 0, -1, 0)
{ finish_args = vmcont;
goto vm_error_continuation_not_rewindable;
}
vm_reinstate_partial_continuation (vm, vmcont, intwinds, sp + 1 - fp, fp);
prevwinds = scm_i_dynwinds ();
vm_reinstate_partial_continuation (vm, vmcont, intwinds, sp + 1 - fp, fp,
vm_cookie);
/* Rewind prompt jmpbuffers, if any. */
{
SCM winds = scm_i_dynwinds ();
for (; !scm_is_eq (winds, prevwinds); winds = scm_cdr (winds))
if (SCM_PROMPT_P (scm_car (winds)) && SCM_PROMPT_SETJMP (scm_car (winds)))
break;
}
CACHE_REGISTER ();
program = SCM_FRAME_PROGRAM (fp);
CACHE_PROGRAM ();
@ -1480,8 +1491,9 @@ VM_DEFINE_INSTRUCTION (83, prompt, "prompt", 4, 2, 0)
SYNC_REGISTER ();
/* Push the prompt onto the dynamic stack. */
prompt = scm_c_make_prompt (k, fp, sp, ip + offset, escape_only_p, vm_cookie);
scm_i_set_dynwinds (scm_cons (prompt, scm_i_dynwinds ()));
prompt = scm_c_make_prompt (k, fp, sp, ip + offset, escape_only_p, vm_cookie,
scm_i_dynwinds ());
scm_i_set_dynwinds (scm_cons (prompt, SCM_PROMPT_DYNWINDS (prompt)));
if (SCM_PROMPT_SETJMP (prompt))
{
/* The prompt exited nonlocally. Cache the regs back from the vp, and go

26
libguile/vm.c
View file

@ -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
}

11
test-suite/tests/control.test
View file

@ -204,3 +204,14 @@
(equal? (k) 1))
(pass-if "post"
(equal? (fluid-ref fl) 0))))
(with-test-prefix "rewinding prompts"
(pass-if "nested prompts"
(let ((k (% 'a
(% 'b
(begin
(abort 'a)
(abort 'b #t))
(lambda (k x) x))
(lambda (k) k))))
(k))))