Remove the unused unbind-all bytecode

It was implemented but never generated, originally intended for
TCO in the pre-lexbind era (which was semantically dubious anyway).
Removing it speeds up the interpreter because there is no longer any
need for the outermost `count` variable unless checking is enabled.

* lisp/emacs-lisp/bytecomp.el:
* lisp/emacs-lisp/comp.el (comp-limplify-lap-inst):
* src/bytecode.c (BYTE_CODES, exec_byte_code):
Remove definition and implementation of unbind-all, freeing up the opcode
for other purposes.

1 files changed, 1 insertions, 7 deletions

diff --git a/src/bytecode.c b/src/bytecode.c
index 635058823c8..97d47a3d9c1 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -227,7 +227,7 @@ DEFINE (Bcondition_case, 0217)	/* Obsolete since Emacs-25.  */         \
 DEFINE (Btemp_output_buffer_setup, 0220) /* Obsolete since Emacs-24.1.  */ \
 DEFINE (Btemp_output_buffer_show, 0221)  /* Obsolete since Emacs-24.1.  */ \
                                                                         \
-DEFINE (Bunbind_all, 0222)      /* Obsolete.  Never used.  */           \
+/* 0222 was Bunbind_all, never used. */                                 \
                                                                         \
 DEFINE (Bset_marker, 0223)                                              \
 DEFINE (Bmatch_beginning, 0224)                                         \
@@ -703,12 +703,6 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
           unbind_to (SPECPDL_INDEX () - op, Qnil);
           NEXT;
 
-        CASE (Bunbind_all):     /* Obsolete.  Never used.  */
-          /* To unbind back to the beginning of this frame.  Not used yet,
-             but will be needed for tail-recursion elimination.  */
-          unbind_to (count, Qnil);
-          NEXT;
-
         CASE (Bgoto):
           op = FETCH2;
         op_branch: