From 4d61badad15e8213c84798b85f10868fc48b94ee Mon Sep 17 00:00:00 2001
From: =?utf8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Fri, 18 Mar 2022 13:58:36 +0100
Subject: [PATCH] Speed up fixnum printing

Use the new number-to-string code to speed up fixnum printing, with
similar results (often more than twice as fast as before).

* src/data.c (Fnumber_to_string): Move fixnum conversion to...
(fixnum_to_string): ... this new function.
* src/lisp.h: (fixnum_to_string): External declaration.
* src/print.c (print_object): Use fixnum_to_string instead of sprintf.
---
 src/data.c  | 38 ++++++++++++++++++++++++--------------
 src/lisp.h  |  1 +
 src/print.c |  6 ++++--
 3 files changed, 29 insertions(+), 16 deletions(-)

diff --git a/src/data.c b/src/data.c
index 6eda0089702..23b0e7c29d9 100644
--- a/src/data.c
+++ b/src/data.c
@@ -2968,6 +2968,29 @@ cons_to_signed (Lisp_Object c, intmax_t min, intmax_t max)
   return val;
 }
 
+/* Render NUMBER in decimal into BUFFER which ends right before END.
+   Return the start of the string; the end is always at END.
+   The string is not null-terminated.  */
+char *
+fixnum_to_string (EMACS_INT number, char *buffer, char *end)
+{
+  EMACS_INT x = number;
+  bool negative = x < 0;
+  if (negative)
+    x = -x;
+  char *p = end;
+  do
+    {
+      eassume (p > buffer && p - 1 < end);
+      *--p = '0' + x % 10;
+      x /= 10;
+    }
+  while (x);
+  if (negative)
+    *--p = '-';
+  return p;
+}
+
 DEFUN ("number-to-string", Fnumber_to_string, Snumber_to_string, 1, 1, 0,
        doc: /* Return the decimal representation of NUMBER as a string.
 Uses a minus sign if negative.
@@ -2978,21 +3001,8 @@ NUMBER may be an integer or a floating point number.  */)
 
   if (FIXNUMP (number))
     {
-      EMACS_INT x = XFIXNUM (number);
-      bool negative = x < 0;
-      if (negative)
-	x = -x;
       char *end = buffer + sizeof buffer;
-      char *p = end;
-      do
-	{
-	  eassume (p > buffer && p - 1 < buffer + sizeof buffer);
-	  *--p = '0' + x % 10;
-	  x /= 10;
-	}
-      while (x);
-      if (negative)
-	*--p = '-';
+      char *p = fixnum_to_string (XFIXNUM (number), buffer, end);
       return make_unibyte_string (p, end - p);
     }
 
diff --git a/src/lisp.h b/src/lisp.h
index 21709b12598..e4d156c0f45 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -622,6 +622,7 @@ extern AVOID args_out_of_range_3 (Lisp_Object, Lisp_Object, Lisp_Object);
 extern AVOID wrong_type_argument (Lisp_Object, Lisp_Object);
 extern Lisp_Object default_value (Lisp_Object symbol);
 extern void defalias (Lisp_Object symbol, Lisp_Object definition);
+extern char *fixnum_to_string (EMACS_INT number, char *buffer, char *end);
 
 
 /* Defined in emacs.c.  */
diff --git a/src/print.c b/src/print.c
index 704fc278f2d..4a68d15fe02 100644
--- a/src/print.c
+++ b/src/print.c
@@ -2060,8 +2060,10 @@ print_object (Lisp_Object obj, Lisp_Object printcharfun, bool escapeflag)
 	  }
 	else
 	  {
-	    int len = sprintf (buf, "%"pI"d", i);
-	    strout (buf, len, len, printcharfun);
+	    char *end = buf + sizeof buf;
+	    char *start = fixnum_to_string (i, buf, end);
+	    ptrdiff_t len = end - start;
+	    strout (start, len, len, printcharfun);
 	  }
       }
       break;
-- 
2.39.2