From: Paul Eggert <eggert@cs.ucla.edu>
Date: Thu, 23 Apr 2020 01:58:45 +0000 (-0700)
Subject: Tweak multibyte parsing loops
X-Git-Tag: emacs-28.0.90~7531
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=023ff119fb511e262e7cd64b8abb7482720ac4a6;p=emacs.git

Tweak multibyte parsing loops

* src/character.c (parse_str_as_multibyte, str_as_multibyte):
Let the fast loop run a little longer, fixing what appears
to be an off-by-1 performance nit.
---

diff --git a/src/character.c b/src/character.c
index da09e77e131..edcec5f1c79 100644
--- a/src/character.c
+++ b/src/character.c
@@ -512,7 +512,7 @@ parse_str_as_multibyte (const unsigned char *str, ptrdiff_t len,
 
   if (len >= MAX_MULTIBYTE_LENGTH)
     {
-      const unsigned char *adjusted_endp = endp - MAX_MULTIBYTE_LENGTH;
+      const unsigned char *adjusted_endp = endp - (MAX_MULTIBYTE_LENGTH - 1);
       while (str < adjusted_endp)
 	{
 	  int n = multibyte_length (str, NULL, false, false);
@@ -556,7 +556,7 @@ str_as_multibyte (unsigned char *str, ptrdiff_t len, ptrdiff_t nbytes,
 
   if (nbytes >= MAX_MULTIBYTE_LENGTH)
     {
-      unsigned char *adjusted_endp = endp - MAX_MULTIBYTE_LENGTH;
+      unsigned char *adjusted_endp = endp - (MAX_MULTIBYTE_LENGTH - 1);
       while (p < adjusted_endp)
 	{
 	  int n = multibyte_length (p, NULL, false, false);
@@ -585,7 +585,7 @@ str_as_multibyte (unsigned char *str, ptrdiff_t len, ptrdiff_t nbytes,
 
   if (nbytes >= MAX_MULTIBYTE_LENGTH)
     {
-      unsigned char *adjusted_endp = endp - MAX_MULTIBYTE_LENGTH;
+      unsigned char *adjusted_endp = endp - (MAX_MULTIBYTE_LENGTH - 1);
       while (p < adjusted_endp)
 	{
 	  int n = multibyte_length (p, NULL, false, false);