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Avoid allocating Lisp_Save_Value for excursions

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* src/editfns.c (save_excursion_save): New arg PDL,
specifying where to save the state.  All uses changed.
(save_excursion_restore): Args are now the marker and info
rather than a pointer to a Lisp_Save_Value containing them.
All uses changed.
* src/eval.c (default_toplevel_binding, Fbacktrace__locals):
Treat excursions like other miscellaneous pdl types.
(record_unwind_protect_excursion): Save data directly
into the pdl rather than creating an object on the heap.
This avoids the need to allocate and free an object.
(do_one_unbind, backtrace_eval_unrewind):
Unwind excursions directly.
(mark_specpdl): Mark excursions directly.
* src/lisp.h (SPECPDL_UNWIND_EXCURSION): New constant.
(union specbinding): New member unwind_excursion.
This commit is contained in:
Paul Eggert 2018-06-14 15:59:09 -07:00
parent 6c04c848e6
commit aca938d1f4
3 changed files with 45 additions and 29 deletions
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27
src/editfns.c
View file

@ -995,30 +995,24 @@ This function does not move point. */)
Qnil, Qt, Qnil);
}
/* Save current buffer state for `save-excursion' special form.
We (ab)use Lisp_Misc_Save_Value to allow explicit free and so
offload some work from GC. */
/* Save current buffer state for save-excursion special form. */
Lisp_Object
save_excursion_save (void)
void
save_excursion_save (union specbinding *pdl)
{
return make_save_obj_obj_obj_obj
(Fpoint_marker (),
Qnil,
/* Selected window if current buffer is shown in it, nil otherwise. */
(EQ (XWINDOW (selected_window)->contents, Fcurrent_buffer ())
? selected_window : Qnil),
Qnil);
eassert (pdl->unwind_excursion.kind == SPECPDL_UNWIND_EXCURSION);
pdl->unwind_excursion.marker = Fpoint_marker ();
/* Selected window if current buffer is shown in it, nil otherwise. */
pdl->unwind_excursion.window
= (EQ (XWINDOW (selected_window)->contents, Fcurrent_buffer ())
? selected_window : Qnil);
}
/* Restore saved buffer before leaving `save-excursion' special form. */
void
save_excursion_restore (Lisp_Object info)
save_excursion_restore (Lisp_Object marker, Lisp_Object window)
{
Lisp_Object marker = XSAVE_OBJECT (info, 0);
Lisp_Object window = XSAVE_OBJECT (info, 2);
free_misc (info);
Lisp_Object buffer = Fmarker_buffer (marker);
/* If we're unwinding to top level, saved buffer may be deleted. This
means that all of its markers are unchained and so BUFFER is nil. */
@ -1027,6 +1021,7 @@ save_excursion_restore (Lisp_Object info)
Fset_buffer (buffer);
/* Point marker. */
Fgoto_char (marker);
unchain_marker (XMARKER (marker));

38
src/eval.c
View file

@ -675,6 +675,7 @@ default_toplevel_binding (Lisp_Object symbol)
case SPECPDL_UNWIND:
case SPECPDL_UNWIND_PTR:
case SPECPDL_UNWIND_INT:
case SPECPDL_UNWIND_EXCURSION:
case SPECPDL_UNWIND_VOID:
case SPECPDL_BACKTRACE:
case SPECPDL_LET_LOCAL:
@ -3427,7 +3428,9 @@ record_unwind_protect_int (void (*function) (int), int arg)
void
record_unwind_protect_excursion (void)
{
record_unwind_protect (save_excursion_restore, save_excursion_save ());
specpdl_ptr->unwind_excursion.kind = SPECPDL_UNWIND_EXCURSION;
save_excursion_save (specpdl_ptr);
grow_specpdl ();
}
void
@ -3475,6 +3478,10 @@ do_one_unbind (union specbinding *this_binding, bool unwinding,
case SPECPDL_UNWIND_VOID:
this_binding->unwind_void.func ();
break;
case SPECPDL_UNWIND_EXCURSION:
save_excursion_restore (this_binding->unwind_excursion.marker,
this_binding->unwind_excursion.window);
break;
case SPECPDL_BACKTRACE:
break;
case SPECPDL_LET:
@ -3749,18 +3756,21 @@ backtrace_eval_unrewind (int distance)
unwind_protect, but the problem is that we don't know how to
rewind them afterwards. */
case SPECPDL_UNWIND:
{
Lisp_Object oldarg = tmp->unwind.arg;
if (tmp->unwind.func == set_buffer_if_live)
if (tmp->unwind.func == set_buffer_if_live)
{
Lisp_Object oldarg = tmp->unwind.arg;
tmp->unwind.arg = Fcurrent_buffer ();
else if (tmp->unwind.func == save_excursion_restore)
tmp->unwind.arg = save_excursion_save ();
else
break;
tmp->unwind.func (oldarg);
break;
set_buffer_if_live (oldarg);
}
break;
case SPECPDL_UNWIND_EXCURSION:
{
Lisp_Object marker = tmp->unwind_excursion.marker;
Lisp_Object window = tmp->unwind_excursion.window;
save_excursion_save (tmp);
save_excursion_restore (marker, window);
}
break;
case SPECPDL_UNWIND_PTR:
case SPECPDL_UNWIND_INT:
case SPECPDL_UNWIND_VOID:
@ -3895,6 +3905,7 @@ NFRAMES and BASE specify the activation frame to use, as in `backtrace-frame'.
case SPECPDL_UNWIND:
case SPECPDL_UNWIND_PTR:
case SPECPDL_UNWIND_INT:
case SPECPDL_UNWIND_EXCURSION:
case SPECPDL_UNWIND_VOID:
case SPECPDL_BACKTRACE:
break;
@ -3924,6 +3935,11 @@ mark_specpdl (union specbinding *first, union specbinding *ptr)
mark_object (specpdl_arg (pdl));
break;
case SPECPDL_UNWIND_EXCURSION:
mark_object (pdl->unwind_excursion.marker);
mark_object (pdl->unwind_excursion.window);
break;
case SPECPDL_BACKTRACE:
{
ptrdiff_t nargs = backtrace_nargs (pdl);

9
src/lisp.h
View file

@ -3188,6 +3188,7 @@ enum specbind_tag {
SPECPDL_UNWIND, /* An unwind_protect function on Lisp_Object. */
SPECPDL_UNWIND_PTR, /* Likewise, on void *. */
SPECPDL_UNWIND_INT, /* Likewise, on int. */
SPECPDL_UNWIND_EXCURSION, /* Likewise, on an execursion. */
SPECPDL_UNWIND_VOID, /* Likewise, with no arg. */
SPECPDL_BACKTRACE, /* An element of the backtrace. */
SPECPDL_LET, /* A plain and simple dynamic let-binding. */
@ -3214,6 +3215,10 @@ union specbinding
void (*func) (int);
int arg;
} unwind_int;
struct {
ENUM_BF (specbind_tag) kind : CHAR_BIT;
Lisp_Object marker, window;
} unwind_excursion;
struct {
ENUM_BF (specbind_tag) kind : CHAR_BIT;
void (*func) (void);
@ -4106,9 +4111,9 @@ extern void mark_threads (void);
/* Defined in editfns.c. */
extern void insert1 (Lisp_Object);
extern Lisp_Object save_excursion_save (void);
extern void save_excursion_save (union specbinding *);
extern void save_excursion_restore (Lisp_Object, Lisp_Object);
extern Lisp_Object save_restriction_save (void);
extern void save_excursion_restore (Lisp_Object);
extern void save_restriction_restore (Lisp_Object);
extern _Noreturn void time_overflow (void);
extern Lisp_Object make_buffer_string (ptrdiff_t, ptrdiff_t, bool);