From: Mattias Engdegård <mattiase@acm.org>
Date: Sun, 2 Jan 2022 10:35:16 +0000 (+0100)
Subject: Remove the unused unbind-all bytecode
X-Git-Tag: emacs-29.0.90~2807
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=721357b86856505324b5f32584d5eae0ba9ab4ac;p=emacs.git

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.
---

diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index a34ba37c04d..2f4bf663438 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -796,11 +796,7 @@ the unwind-action")
 (byte-defop 144  0 byte-temp-output-buffer-setup-OBSOLETE)
 (byte-defop 145 -1 byte-temp-output-buffer-show-OBSOLETE)
 
-;; these ops are new to v19
-
-;; To unbind back to the beginning of this frame.
-;; Not used yet, but will be needed for tail-recursion elimination.
-(byte-defop 146  0 byte-unbind-all)
+;; unused: 146
 
 ;; these ops are new to v19
 (byte-defop 147 -2 byte-set-marker)
diff --git a/lisp/emacs-lisp/comp.el b/lisp/emacs-lisp/comp.el
index 74b0b1197be..3c61063a3cb 100644
--- a/lisp/emacs-lisp/comp.el
+++ b/lisp/emacs-lisp/comp.el
@@ -1943,7 +1943,6 @@ and the annotation emission."
       (byte-condition-case) ;; Obsolete
       (byte-temp-output-buffer-setup-OBSOLETE)
       (byte-temp-output-buffer-show-OBSOLETE)
-      (byte-unbind-all) ;; Obsolete
       (byte-set-marker auto)
       (byte-match-beginning auto)
       (byte-match-end auto)
diff --git a/src/bytecode.c b/src/bytecode.c
index 75f1a6b43e5..b2e8f4a9166 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: