From 1eacfb3c888764908d2ee421e16c020e7343b5a1 Mon Sep 17 00:00:00 2001
From: Mattias Engdegård
Date: Sun, 2 Jan 2022 11:35:16 +0100
Subject: 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.
---
 src/bytecode.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

(limited to 'src/bytecode.c')

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:
-- 
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