Tune by using memchr and memrchr.

* .bzrignore: Add string.h.
* admin/merge-gnulib (GNULIB_MODULES): Add memrchr.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* lib/memrchr.c, lib/string.in.h, m4/memrchr.m4, m4/string_h.m4:
New files, from gnulib.
* src/doc.c (Fsnarf_documentation):
* src/fileio.c (Fsubstitute_in_file_name):
* src/search.c (find_newline, scan_newline):
* src/xdisp.c (pos_visible_p, display_count_lines):
Use memchr and memrchr rather than scanning byte-by-byte.
* src/search.c (find_newline): Rename from scan_buffer.
Omit first arg TARGET, as it's always '\n'.  All callers changed.

3 files changed, 156 insertions, 0 deletions

diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index 8098a52e501..a7987120c50 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -83,6 +83,7 @@ AC_DEFUN([gl_EARLY],
   AC_REQUIRE([AC_SYS_LARGEFILE])
   # Code from module lstat:
   # Code from module manywarnings:
+  # Code from module memrchr:
   # Code from module mktime:
   # Code from module multiarch:
   # Code from module nocrash:
@@ -117,6 +118,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module stdio:
   # Code from module stdlib:
   # Code from module strftime:
+  # Code from module string:
   # Code from module strtoimax:
   # Code from module strtoll:
   # Code from module strtoull:
@@ -242,6 +244,12 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_LSTAT
   fi
   gl_SYS_STAT_MODULE_INDICATOR([lstat])
+  gl_FUNC_MEMRCHR
+  if test $ac_cv_func_memrchr = no; then
+    AC_LIBOBJ([memrchr])
+    gl_PREREQ_MEMRCHR
+  fi
+  gl_STRING_MODULE_INDICATOR([memrchr])
   gl_FUNC_MKTIME
   if test $REPLACE_MKTIME = 1; then
     AC_LIBOBJ([mktime])
@@ -294,6 +302,7 @@ AC_DEFUN([gl_INIT],
   gl_STDIO_H
   gl_STDLIB_H
   gl_FUNC_GNU_STRFTIME
+  gl_HEADER_STRING_H
   gl_FUNC_STRTOIMAX
   if test $HAVE_STRTOIMAX = 0 || test $REPLACE_STRTOIMAX = 1; then
     AC_LIBOBJ([strtoimax])
@@ -757,6 +766,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/lstat.c
   lib/md5.c
   lib/md5.h
+  lib/memrchr.c
   lib/mktime-internal.h
   lib/mktime.c
   lib/openat-priv.h
@@ -790,6 +800,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/stdlib.in.h
   lib/strftime.c
   lib/strftime.h
+  lib/string.in.h
   lib/strtoimax.c
   lib/strtol.c
   lib/strtoll.c
@@ -848,6 +859,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/lstat.m4
   m4/manywarnings.m4
   m4/md5.m4
+  m4/memrchr.m4
   m4/mktime.m4
   m4/multiarch.m4
   m4/nocrash.m4
@@ -877,6 +889,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/stdio_h.m4
   m4/stdlib_h.m4
   m4/strftime.m4
+  m4/string_h.m4
   m4/strtoimax.m4
   m4/strtoll.m4
   m4/strtoull.m4
diff --git a/m4/memrchr.m4 b/m4/memrchr.m4
new file mode 100644
index 00000000000..5920f5747b7
--- /dev/null
+++ b/m4/memrchr.m4
@@ -0,0 +1,23 @@
+# memrchr.m4 serial 10
+dnl Copyright (C) 2002-2003, 2005-2007, 2009-2013 Free Software Foundation,
+dnl Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_MEMRCHR],
+[
+  dnl Persuade glibc <string.h> to declare memrchr().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  AC_CHECK_DECLS_ONCE([memrchr])
+  if test $ac_cv_have_decl_memrchr = no; then
+    HAVE_DECL_MEMRCHR=0
+  fi
+
+  AC_CHECK_FUNCS([memrchr])
+])
+
+# Prerequisites of lib/memrchr.c.
+AC_DEFUN([gl_PREREQ_MEMRCHR], [:])
diff --git a/m4/string_h.m4 b/m4/string_h.m4
new file mode 100644
index 00000000000..cc5fbbb32ff
--- /dev/null
+++ b/m4/string_h.m4
@@ -0,0 +1,120 @@
+# Configure a GNU-like replacement for <string.h>.
+
+# Copyright (C) 2007-2013 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# serial 21
+
+# Written by Paul Eggert.
+
+AC_DEFUN([gl_HEADER_STRING_H],
+[
+  dnl Use AC_REQUIRE here, so that the default behavior below is expanded
+  dnl once only, before all statements that occur in other macros.
+  AC_REQUIRE([gl_HEADER_STRING_H_BODY])
+])
+
+AC_DEFUN([gl_HEADER_STRING_H_BODY],
+[
+  AC_REQUIRE([AC_C_RESTRICT])
+  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  gl_NEXT_HEADERS([string.h])
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use, and which is not
+  dnl guaranteed by C89.
+  gl_WARN_ON_USE_PREPARE([[#include <string.h>
+    ]],
+    [ffsl ffsll memmem mempcpy memrchr rawmemchr stpcpy stpncpy strchrnul
+     strdup strncat strndup strnlen strpbrk strsep strcasestr strtok_r
+     strerror_r strsignal strverscmp])
+])
+
+AC_DEFUN([gl_STRING_MODULE_INDICATOR],
+[
+  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
+  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+AC_DEFUN([gl_HEADER_STRING_H_DEFAULTS],
+[
+  GNULIB_FFSL=0;        AC_SUBST([GNULIB_FFSL])
+  GNULIB_FFSLL=0;       AC_SUBST([GNULIB_FFSLL])
+  GNULIB_MEMCHR=0;      AC_SUBST([GNULIB_MEMCHR])
+  GNULIB_MEMMEM=0;      AC_SUBST([GNULIB_MEMMEM])
+  GNULIB_MEMPCPY=0;     AC_SUBST([GNULIB_MEMPCPY])
+  GNULIB_MEMRCHR=0;     AC_SUBST([GNULIB_MEMRCHR])
+  GNULIB_RAWMEMCHR=0;   AC_SUBST([GNULIB_RAWMEMCHR])
+  GNULIB_STPCPY=0;      AC_SUBST([GNULIB_STPCPY])
+  GNULIB_STPNCPY=0;     AC_SUBST([GNULIB_STPNCPY])
+  GNULIB_STRCHRNUL=0;   AC_SUBST([GNULIB_STRCHRNUL])
+  GNULIB_STRDUP=0;      AC_SUBST([GNULIB_STRDUP])
+  GNULIB_STRNCAT=0;     AC_SUBST([GNULIB_STRNCAT])
+  GNULIB_STRNDUP=0;     AC_SUBST([GNULIB_STRNDUP])
+  GNULIB_STRNLEN=0;     AC_SUBST([GNULIB_STRNLEN])
+  GNULIB_STRPBRK=0;     AC_SUBST([GNULIB_STRPBRK])
+  GNULIB_STRSEP=0;      AC_SUBST([GNULIB_STRSEP])
+  GNULIB_STRSTR=0;      AC_SUBST([GNULIB_STRSTR])
+  GNULIB_STRCASESTR=0;  AC_SUBST([GNULIB_STRCASESTR])
+  GNULIB_STRTOK_R=0;    AC_SUBST([GNULIB_STRTOK_R])
+  GNULIB_MBSLEN=0;      AC_SUBST([GNULIB_MBSLEN])
+  GNULIB_MBSNLEN=0;     AC_SUBST([GNULIB_MBSNLEN])
+  GNULIB_MBSCHR=0;      AC_SUBST([GNULIB_MBSCHR])
+  GNULIB_MBSRCHR=0;     AC_SUBST([GNULIB_MBSRCHR])
+  GNULIB_MBSSTR=0;      AC_SUBST([GNULIB_MBSSTR])
+  GNULIB_MBSCASECMP=0;  AC_SUBST([GNULIB_MBSCASECMP])
+  GNULIB_MBSNCASECMP=0; AC_SUBST([GNULIB_MBSNCASECMP])
+  GNULIB_MBSPCASECMP=0; AC_SUBST([GNULIB_MBSPCASECMP])
+  GNULIB_MBSCASESTR=0;  AC_SUBST([GNULIB_MBSCASESTR])
+  GNULIB_MBSCSPN=0;     AC_SUBST([GNULIB_MBSCSPN])
+  GNULIB_MBSPBRK=0;     AC_SUBST([GNULIB_MBSPBRK])
+  GNULIB_MBSSPN=0;      AC_SUBST([GNULIB_MBSSPN])
+  GNULIB_MBSSEP=0;      AC_SUBST([GNULIB_MBSSEP])
+  GNULIB_MBSTOK_R=0;    AC_SUBST([GNULIB_MBSTOK_R])
+  GNULIB_STRERROR=0;    AC_SUBST([GNULIB_STRERROR])
+  GNULIB_STRERROR_R=0;  AC_SUBST([GNULIB_STRERROR_R])
+  GNULIB_STRSIGNAL=0;   AC_SUBST([GNULIB_STRSIGNAL])
+  GNULIB_STRVERSCMP=0;  AC_SUBST([GNULIB_STRVERSCMP])
+  HAVE_MBSLEN=0;        AC_SUBST([HAVE_MBSLEN])
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_FFSL=1;                  AC_SUBST([HAVE_FFSL])
+  HAVE_FFSLL=1;                 AC_SUBST([HAVE_FFSLL])
+  HAVE_MEMCHR=1;                AC_SUBST([HAVE_MEMCHR])
+  HAVE_DECL_MEMMEM=1;           AC_SUBST([HAVE_DECL_MEMMEM])
+  HAVE_MEMPCPY=1;               AC_SUBST([HAVE_MEMPCPY])
+  HAVE_DECL_MEMRCHR=1;          AC_SUBST([HAVE_DECL_MEMRCHR])
+  HAVE_RAWMEMCHR=1;             AC_SUBST([HAVE_RAWMEMCHR])
+  HAVE_STPCPY=1;                AC_SUBST([HAVE_STPCPY])
+  HAVE_STPNCPY=1;               AC_SUBST([HAVE_STPNCPY])
+  HAVE_STRCHRNUL=1;             AC_SUBST([HAVE_STRCHRNUL])
+  HAVE_DECL_STRDUP=1;           AC_SUBST([HAVE_DECL_STRDUP])
+  HAVE_DECL_STRNDUP=1;          AC_SUBST([HAVE_DECL_STRNDUP])
+  HAVE_DECL_STRNLEN=1;          AC_SUBST([HAVE_DECL_STRNLEN])
+  HAVE_STRPBRK=1;               AC_SUBST([HAVE_STRPBRK])
+  HAVE_STRSEP=1;                AC_SUBST([HAVE_STRSEP])
+  HAVE_STRCASESTR=1;            AC_SUBST([HAVE_STRCASESTR])
+  HAVE_DECL_STRTOK_R=1;         AC_SUBST([HAVE_DECL_STRTOK_R])
+  HAVE_DECL_STRERROR_R=1;       AC_SUBST([HAVE_DECL_STRERROR_R])
+  HAVE_DECL_STRSIGNAL=1;        AC_SUBST([HAVE_DECL_STRSIGNAL])
+  HAVE_STRVERSCMP=1;            AC_SUBST([HAVE_STRVERSCMP])
+  REPLACE_MEMCHR=0;             AC_SUBST([REPLACE_MEMCHR])
+  REPLACE_MEMMEM=0;             AC_SUBST([REPLACE_MEMMEM])
+  REPLACE_STPNCPY=0;            AC_SUBST([REPLACE_STPNCPY])
+  REPLACE_STRDUP=0;             AC_SUBST([REPLACE_STRDUP])
+  REPLACE_STRSTR=0;             AC_SUBST([REPLACE_STRSTR])
+  REPLACE_STRCASESTR=0;         AC_SUBST([REPLACE_STRCASESTR])
+  REPLACE_STRCHRNUL=0;          AC_SUBST([REPLACE_STRCHRNUL])
+  REPLACE_STRERROR=0;           AC_SUBST([REPLACE_STRERROR])
+  REPLACE_STRERROR_R=0;         AC_SUBST([REPLACE_STRERROR_R])
+  REPLACE_STRNCAT=0;            AC_SUBST([REPLACE_STRNCAT])
+  REPLACE_STRNDUP=0;            AC_SUBST([REPLACE_STRNDUP])
+  REPLACE_STRNLEN=0;            AC_SUBST([REPLACE_STRNLEN])
+  REPLACE_STRSIGNAL=0;          AC_SUBST([REPLACE_STRSIGNAL])
+  REPLACE_STRTOK_R=0;           AC_SUBST([REPLACE_STRTOK_R])
+  UNDEFINE_STRTOK_R=0;          AC_SUBST([UNDEFINE_STRTOK_R])
+])