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dynstack: pushing a prompt no longer allocates memory

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* libguile/control.h: Remove scm_t_prompt_registers and
  scm_c_make_prompt_registers.
  (scm_c_abort): Take a pointer to a jmpbuf instead of a cookie.  It
  will serve the same purpose.
* libguile/control.c (reify_partial_continuation, scm_at_abort): Adapt
  to new prompt representation.

* libguile/dynstack.h:
* libguile/dynstack.c (scm_dynstack_push_prompt): Prompts now have 5
  words instead of 2, as they now push the fp, sp, ip, and jmpbuf on the
  stack separately.  This avoids allocation.
  (scm_dynstack_find_prompt): Likewise, add return values for fp, sp,
  etc.
  (scm_dynstack_wind_prompt): Replaces scm_dynstack_relocate_prompt.

* libguile/eval.c (eval):
* libguile/stacks.c (find_prompt):
* libguile/throw.c (pre_init_catch): Adapt to the new prompt mechanism.

* libguile/vm-engine.c (vm_engine): Setjmp an on-stack jmpbuf every time
  the VM enters.  We can then re-use that jmpbuf for all prompts in that
  invocation.

* libguile/vm-i-system.c (partial_cont_call): Adapt to change in prompt
  representation.  We don't need to wind here any more, since we pass in
  the prompt's jmpbuf.
  (prompt): Adapt to scm_dynstack_push_prompt change.
  (abort): Adapt to vm_abort change.

* libguile/vm.h (struct scm_vm): No more cookie.

* libguile/vm.c (vm_abort): Adapt to scm_c_abort change.
  (vm_reinstate_partial_continuation): Rewind the dynamic stack here,
  now that we do have a valid jmpbuf.
  (make_vm): No need to initialize a cookie.
This commit is contained in:
Andy Wingo 2012-03-07 10:27:16 +01:00
parent 3c12fc3595
commit 9d381ba478
11 changed files with 148 additions and 178 deletions
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21
libguile/vm-engine.c
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@ -53,13 +53,14 @@ VM_NAME (SCM vm, SCM program, SCM *argv, int nargs)
SCM *stack_limit = vp->stack_limit; /* stack limit address */
scm_i_thread *current_thread = SCM_I_CURRENT_THREAD;
scm_t_int64 vm_cookie = vp->cookie++;
/* Internal variables */
int nvalues = 0;
const char *func_name = NULL; /* used for error reporting */
SCM finish_args; /* used both for returns: both in error
and normal situations */
scm_i_jmp_buf registers; /* used for prompts */
#ifdef HAVE_LABELS_AS_VALUES
static const void **jump_table_pointer = NULL;
#endif
@ -88,6 +89,24 @@ VM_NAME (SCM vm, SCM program, SCM *argv, int nargs)
jump_table = jump_table_pointer;
#endif
if (SCM_I_SETJMP (registers))
{
/* Non-local return. Cache the VM registers back from the vp, and
go to the handler.
Note, at this point, we must assume that any variable local to
vm_engine that can be assigned *has* been assigned. So we need to pull
all our state back from the ip/fp/sp.
*/
CACHE_REGISTER ();
program = SCM_FRAME_PROGRAM (fp);
CACHE_PROGRAM ();
/* The stack contains the values returned to this continuation,
along with a number-of-values marker -- like an MV return. */
ABORT_CONTINUATION_HOOK ();
NEXT;
}
/* Initialization */
{
SCM prog = program;