dnl Check for __builtin_expect.

dnl Copyright 2016-2017 Free Software Foundation, 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.

dnl Written by Paul Eggert.

AC_DEFUN([gl___BUILTIN_EXPECT],

[

  AC_CACHE_CHECK([for __builtin_expect],

    [gl_cv___builtin_expect],

    [AC_LINK_IFELSE(

       [AC_LANG_SOURCE([[

         int

         main (int argc, char **argv)

         {

           argc = __builtin_expect (argc, 100);

           return argv[argc != 100][0];

         }]])],

       [gl_cv___builtin_expect=yes],

       [AC_LINK_IFELSE(

          [AC_LANG_SOURCE([[

             #include <builtins.h>

             int

             main (int argc, char **argv)

             {

               argc = __builtin_expect (argc, 100);

               return argv[argc != 100][0];

             }]])],

          [gl_cv___builtin_expect="in <builtins.h>"],

          [gl_cv___builtin_expect=no])])])

  if test "$gl_cv___builtin_expect" = yes; then

    AC_DEFINE([HAVE___BUILTIN_EXPECT], [1])

  elif test "$gl_cv___builtin_expect" = "in <builtins.h>"; then

    AC_DEFINE([HAVE___BUILTIN_EXPECT], [2])

  fi

  AH_VERBATIM([HAVE___BUILTIN_EXPECT],

    [/* Define to 1 if the compiler supports __builtin_expect,

   and to 2 if <builtins.h> does.  */

#undef HAVE___BUILTIN_EXPECT

#ifndef HAVE___BUILTIN_EXPECT

# define __builtin_expect(e, c) (e)

#elif HAVE___BUILTIN_EXPECT == 2

# include <builtins.h>

#endif

    ])

])