Maintain end of specpdl instead of size

Keep track of the end of specpdl explicitly since that is what we are
comparing against on critical code paths.

* src/eval.c (init_eval_once_for_pdumper, signal_or_quit)
(grow_specpdl_allocation):
* src/fileio.c (Fdo_auto_save):
* src/lisp.h (grow_specpdl):
* src/thread.c (run_thread, Fmake_thread):
* src/thread.h (struct thread_state):
Replace specpdl_size with specpdl_end, according to the equation
specpdl_end = specpdl + specpdl_size.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/thread.h b/src/thread.h
index 1e7eb86f6ee..f2755045b2e 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -92,14 +92,14 @@ struct thread_state
   struct handler *m_handlerlist_sentinel;
 #define handlerlist_sentinel (current_thread->m_handlerlist_sentinel)
 
-  /* Current number of specbindings allocated in specpdl.  */
-  ptrdiff_t m_specpdl_size;
-#define specpdl_size (current_thread->m_specpdl_size)
-
   /* Pointer to beginning of specpdl.  */
   union specbinding *m_specpdl;
 #define specpdl (current_thread->m_specpdl)
 
+  /* End of specpld (just beyond the last element).  */
+  union specbinding *m_specpdl_end;
+#define specpdl_end (current_thread->m_specpdl_end)
+
   /* Pointer to first unused element in specpdl.  */
   union specbinding *m_specpdl_ptr;
 #define specpdl_ptr (current_thread->m_specpdl_ptr)