scm_i_make_continuation takes vm and vm_cont args explicitly

* libguile/continuations.h:
* libguile/continuations.c (scm_i_make_continuation): Take VM and VM
  continuation arguments as well; I'm not convinced that saving all VM
  continuations was the right thing, and in any case we only ever saved
  the latest. Running a new VM should create a continuation barrier.

* libguile/stacks.c (scm_make_stack):
* libguile/vm-i-system.c (call/cc, tail-call/cc): Adapt callers.

* libguile/vm.h (scm_i_vm_capture_continuation)
  (scm_i_vm_reinstate_continuation): Change to be internal, and to only
  capture and reinstate continuations for a particular VM.

libguile/continuations.c

@@ -191,7 +191,7 @@ continuation_print (SCM obj, SCM port, scm_print_state *state SCM_UNUSED)
    continuation.  */
 #define FUNC_NAME "scm_i_make_continuation"
 SCM 
-scm_i_make_continuation (int *first)
+scm_i_make_continuation (int *first, SCM vm, SCM vm_cont)
 {
   scm_i_thread *thread = SCM_I_CURRENT_THREAD;
   SCM cont;
@@ -214,7 +214,8 @@ scm_i_make_continuation (int *first)
 #endif
   continuation->offset = continuation->stack - src;
   memcpy (continuation->stack, src, sizeof (SCM_STACKITEM) * stack_size);
-  continuation->vm_conts = scm_vm_capture_continuations ();
+  continuation->vm = vm;
+  continuation->vm_cont = vm_cont;
 
   SCM_NEWSMOB (cont, tc16_continuation, continuation);
 
@@ -265,13 +266,10 @@ scm_i_continuation_to_frame (SCM continuation)
   contregs = scm_c_vector_ref (scm_program_objects (continuation), 0);
   cont = SCM_CONTREGS (contregs);
 
-  if (!scm_is_null (cont->vm_conts))
+  if (scm_is_true (cont->vm_cont))
     {
-      SCM vm_cont;
-      struct scm_vm_cont *data;
-      vm_cont = scm_cdr (scm_car (cont->vm_conts));
-      data = SCM_VM_CONT_DATA (vm_cont);
-      return scm_c_make_frame (vm_cont,
+      struct scm_vm_cont *data = SCM_VM_CONT_DATA (cont->vm_cont);
+      return scm_c_make_frame (cont->vm_cont,
                                data->fp + data->reloc,
                                data->sp + data->reloc,
                                data->ip,
@@ -334,7 +332,8 @@ copy_stack (void *data)
   copy_stack_data *d = (copy_stack_data *)data;
   memcpy (d->dst, d->continuation->stack,
 	  sizeof (SCM_STACKITEM) * d->continuation->num_stack_items);
-  scm_vm_reinstate_continuations (d->continuation->vm_conts);
+  scm_i_vm_reinstate_continuation (d->continuation->vm,
+                                   d->continuation->vm_cont);
 #ifdef __ia64__
   SCM_I_CURRENT_THREAD->pending_rbs_continuation = d->continuation;
 #endif

libguile/continuations.h

@@ -53,7 +53,8 @@ typedef struct
 #endif /* __ia64__ */
   size_t num_stack_items;   /* size of the saved stack.  */
   SCM root;                 /* continuation root identifier.  */
-  SCM vm_conts;             /* vm continuations (they use separate stacks) */
+  SCM vm;                   /* vm */
+  SCM vm_cont;              /* vm's stack and regs */
 
   /* The offset from the live stack location to this copy.  This is
      used to adjust pointers from within the copied stack to the stack
@@ -71,7 +72,7 @@ typedef struct
 
 
 
-SCM_INTERNAL SCM scm_i_make_continuation (int *first);
+SCM_INTERNAL SCM scm_i_make_continuation (int *first, SCM vm, SCM vm_cont);
 SCM_INTERNAL SCM scm_i_call_with_current_continuation (SCM proc);
 SCM_INTERNAL SCM scm_i_continuation_to_frame (SCM cont);
 SCM_INTERNAL void scm_i_continuation_call (SCM cont, size_t n, SCM *argv);

libguile/stacks.c

@@ -199,7 +199,7 @@ SCM_DEFINE (scm_make_stack, "make-stack", 1, 0, 1,
       SCM cont;
       struct scm_vm_cont *c;
 
-      cont = scm_cdar (scm_vm_capture_continuations ());
+      cont = scm_i_vm_capture_continuation (scm_the_vm ());
       c = SCM_VM_CONT_DATA (cont);
 
       frame = scm_c_make_frame (cont, c->fp + c->reloc,

libguile/vm-i-system.c

@@ -1093,7 +1093,7 @@ VM_DEFINE_INSTRUCTION (64, call_cc, "call/cc", 0, 1, 1)
   SCM proc, cont;
   POP (proc);
   SYNC_ALL ();
-  cont = scm_i_make_continuation (&first);
+  cont = scm_i_make_continuation (&first, vm, capture_vm_cont (vp));
   if (first) 
     {
       PUSH ((SCM)fp); /* dynamic link */
@@ -1130,7 +1130,7 @@ VM_DEFINE_INSTRUCTION (65, tail_call_cc, "tail-call/cc", 0, 1, 1)
   SCM proc, cont;
   POP (proc);
   SYNC_ALL ();
-  cont = scm_i_make_continuation (&first);
+  cont = scm_i_make_continuation (&first, vm, capture_vm_cont (vp));
   ASSERT (sp == vp->sp);
   ASSERT (fp == vp->fp);
   if (first) 

libguile/vm.c

@@ -137,17 +137,15 @@ reinstate_vm_cont (struct scm_vm *vp, SCM cont)
    call to vm_run; but that's currently not implemented.
  */
 SCM
-scm_vm_capture_continuations (void)
+scm_i_vm_capture_continuation (SCM vm)
 {
-  SCM vm = scm_the_vm ();
-  return scm_acons (vm, capture_vm_cont (SCM_VM_DATA (vm)), SCM_EOL);
+  return capture_vm_cont (SCM_VM_DATA (vm));
 }
 
 void
-scm_vm_reinstate_continuations (SCM conts)
+scm_i_vm_reinstate_continuation (SCM vm, SCM cont)
 {
-  for (; conts != SCM_EOL; conts = SCM_CDR (conts))
-    reinstate_vm_cont (SCM_VM_DATA (SCM_CAAR (conts)), SCM_CDAR (conts));
+  reinstate_vm_cont (SCM_VM_DATA (vm), cont);
 }
 
 static void

libguile/vm.h

@@ -98,8 +98,8 @@ struct scm_vm_cont {
 #define SCM_VM_CONT_P(OBJ)	(SCM_NIMP (OBJ) && SCM_TYP7 (OBJ) == scm_tc7_vm_cont)
 #define SCM_VM_CONT_DATA(CONT)	((struct scm_vm_cont *) SCM_CELL_WORD_1 (CONT))
 
-SCM_API SCM scm_vm_capture_continuations (void);
-SCM_API void scm_vm_reinstate_continuations (SCM conts);
+SCM_INTERNAL SCM scm_i_vm_capture_continuation (SCM vm);
+SCM_INTERNAL void scm_i_vm_reinstate_continuation (SCM vm, SCM cont);
 
 SCM_API SCM scm_load_compiled_with_vm (SCM file);