Merge the specpdl and backtrace stacks. Make the structure of the

specpdl entries more obvious via a tagged union of structs.
* src/lisp.h (BITS_PER_PTRDIFF_T): New constant.
(enum specbind_tag): New enum.
(struct specbinding): Make it a tagged union of structs.
Add a case for backtrace records.
(specpdl_symbol, specpdl_old_value, specpdl_where, specpdl_arg)
(specpdl_func, backtrace_function, backtrace_nargs, backtrace_args)
(backtrace_debug_on_exit): New accessors.
(struct backtrace): Remove.
(struct catchtag): Remove backlist field.
* src/data.c (let_shadows_buffer_binding_p, let_shadows_global_binding_p):
Move to eval.c.
(Flocal_variable_p): Speed up the common case where the binding is
already loaded.
* src/eval.c (backtrace_list): Remove.
(set_specpdl_symbol, set_specpdl_old_value): Remove.
(set_backtrace_args, set_backtrace_nargs)
(set_backtrace_debug_on_exit, backtrace_p, backtrace_top)
(backtrace_next): New functions.
(Fdefvaralias, Fdefvar): Adjust to new specpdl format.
(unwind_to_catch, internal_lisp_condition_case)
(internal_condition_case, internal_condition_case_1)
(internal_condition_case_2, internal_condition_case_n): Don't bother
with backtrace_list any more.
(Fsignal): Adjust to new backtrace format.
(grow_specpdl): Move up.
(record_in_backtrace): New function.
(eval_sub, Ffuncall): Use it.
(apply_lambda): Adjust to new backtrace format.
(let_shadows_buffer_binding_p, let_shadows_global_binding_p): Move from
data.c.
(specbind): Adjust to new specpdl format.  Simplify.
(record_unwind_protect, unbind_to): Adjust to new specpdl format.
(Fbacktrace_debug, Fbacktrace, Fbacktrace_frame): Adjust to new
backtrace format.
(mark_backtrace): Remove.
(mark_specpdl, get_backtrace, backtrace_top_function): New functions.
* src/xdisp.c (redisplay_internal): Use record_in_backtrace.
* src/alloc.c (Fgarbage_collect): Use record_in_backtrace.
Use mark_specpdl.
* src/profiler.c (record_backtrace): Use get_backtrace.
(handle_profiler_signal): Use backtrace_top_function.
* src/.gdbinit (xbacktrace, hookpost-backtrace): Use new backtrace
accessor functions.

1 files changed, 12 insertions, 45 deletions

diff --git a/src/data.c b/src/data.c
index 6622088b648..b33d9656d57 100644
--- a/src/data.c
+++ b/src/data.c
@@ -1069,40 +1069,6 @@ DEFUN ("set", Fset, Sset, 2, 2, 0,
   return newval;
 }
 
-/* Return true if SYMBOL currently has a let-binding
-   which was made in the buffer that is now current.  */
-
-static bool
-let_shadows_buffer_binding_p (struct Lisp_Symbol *symbol)
-{
-  struct specbinding *p;
-
-  for (p = specpdl_ptr; p > specpdl; )
-    if ((--p)->func == NULL
-        && CONSP (p->symbol))
-      {
-        struct Lisp_Symbol *let_bound_symbol = XSYMBOL (XCAR (p->symbol));
-        eassert (let_bound_symbol->redirect != SYMBOL_VARALIAS);
-        if (symbol == let_bound_symbol
-            && XBUFFER (XCDR (XCDR (p->symbol))) == current_buffer)
-          return 1;
-      }
-
-  return 0;
-}
-
-static bool
-let_shadows_global_binding_p (Lisp_Object symbol)
-{
-  struct specbinding *p;
-
-  for (p = specpdl_ptr; p > specpdl; )
-    if ((--p)->func == NULL && EQ (p->symbol, symbol))
-      return 1;
-
-  return 0;
-}
-
 /* Store the value NEWVAL into SYMBOL.
    If buffer/frame-locality is an issue, WHERE specifies which context to use.
    (nil stands for the current buffer/frame).
@@ -1841,17 +1807,18 @@ BUFFER defaults to the current buffer.  */)
         XSETBUFFER (tmp, buf);
         XSETSYMBOL (variable, sym); /* Update in case of aliasing.  */
 
-        for (tail = BVAR (buf, local_var_alist); CONSP (tail); tail = XCDR (tail))
-          {
-            elt = XCAR (tail);
-            if (EQ (variable, XCAR (elt)))
-              {
-                eassert (!blv->frame_local);
-                eassert (blv_found (blv) || !EQ (blv->where, tmp));
-                return Qt;
-              }
-          }
-        eassert (!blv_found (blv) || !EQ (blv->where, tmp));
+        if (EQ (blv->where, tmp)) /* The binding is already loaded.  */
+          return blv_found (blv) ? Qt : Qnil;
+        else
+          for (tail = BVAR (buf, local_var_alist); CONSP (tail); tail = XCDR (tail))
+            {
+              elt = XCAR (tail);
+              if (EQ (variable, XCAR (elt)))
+                {
+                  eassert (!blv->frame_local);
+                  return Qt;
+                }
+            }
         return Qnil;
       }
     case SYMBOL_FORWARDED: