Generate 'substring' byte op (bug#39709)

The 'substring' byte op was not emitted, apparently by mistake.  Fix.
Suggested by Mark Oteiza <mvoteiza@udel.edu>.

* lisp/emacs-lisp/bytecomp.el (byte-defop-compiler): Add '1-3' clause.
(byte-compile-one-to-three-args): New.
* lisp/emacs-lisp/byte-opt.el (byte-compile-side-effect-free-ops):
Add 'byte-substring'.
* test/lisp/emacs-lisp/bytecomp-tests.el
(byte-opt-testsuite-arith-data): Test 'substring'.

3 files changed, 16 insertions, 3 deletions

diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index fe0930c684b..4f72251aed5 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -1515,7 +1515,7 @@
      byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate
      byte-plus byte-max byte-min byte-mult byte-char-after byte-char-syntax
      byte-buffer-substring byte-string= byte-string< byte-nthcdr byte-elt
-     byte-member byte-assq byte-quo byte-rem)
+     byte-member byte-assq byte-quo byte-rem byte-substring)
    byte-compile-side-effect-and-error-free-ops))
 
 ;; This crock is because of the way DEFVAR_BOOL variables work.
diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 24a36393b2e..63348456a15 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -3487,7 +3487,7 @@ the opcode to be used.  If function is a list, the first element
 is the function and the second element is the bytecode-symbol.
 The second element may be nil, meaning there is no opcode.
 COMPILE-HANDLER is the function to use to compile this byte-op, or
-may be the abbreviations 0, 1, 2, 3, 0-1, or 1-2.
+may be the abbreviations 0, 1, 2, 2-and, 3, 0-1, 1-2, 1-3, or 2-3.
 If it is nil, then the handler is \"byte-compile-SYMBOL.\""
   (let (opcode)
     (if (symbolp function)
@@ -3506,6 +3506,7 @@ If it is nil, then the handler is \"byte-compile-SYMBOL.\""
                                         (0-1 . byte-compile-zero-or-one-arg)
                                         (1-2 . byte-compile-one-or-two-args)
                                         (2-3 . byte-compile-two-or-three-args)
+                                        (1-3 . byte-compile-one-to-three-args)
                                         )))
                            compile-handler
                            (intern (concat "byte-compile-"
@@ -3690,6 +3691,13 @@ These implicitly `and' together a bunch of two-arg bytecodes."
           ((= len 4) (byte-compile-three-args form))
           (t (byte-compile-subr-wrong-args form "2-3")))))
 
+(defun byte-compile-one-to-three-args (form)
+  (let ((len (length form)))
+    (cond ((= len 2) (byte-compile-three-args (append form '(nil nil))))
+          ((= len 3) (byte-compile-three-args (append form '(nil))))
+          ((= len 4) (byte-compile-three-args form))
+          (t (byte-compile-subr-wrong-args form "1-3")))))
+
 (defun byte-compile-noop (_form)
   (byte-compile-constant nil))
 
diff --git a/test/lisp/emacs-lisp/bytecomp-tests.el b/test/lisp/emacs-lisp/bytecomp-tests.el
index de11ae22d50..d4ceb47c36e 100644
--- a/test/lisp/emacs-lisp/bytecomp-tests.el
+++ b/test/lisp/emacs-lisp/bytecomp-tests.el
@@ -347,7 +347,12 @@
                                 ((eq x 't) 99)
                                 (t 999))))
             '((a c) (b c) (7 c) (-3 c) (nil nil) (t c) (q c) (r c) (s c)
-              (t c) (x "a") (x "c") (x c) (x d) (x e))))
+              (t c) (x "a") (x "c") (x c) (x d) (x e)))
+
+    ;; `substring' bytecode generation (bug#39709).
+    (substring "abcdef")
+    (substring "abcdef" 2)
+    (substring "abcdef" 3 2))
   "List of expression for test.
 Each element will be executed by interpreter and with
 bytecompiled code, and their results compared.")