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dnl Check for __builtin_expect.
dnl Copyright 2016-2021 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
])
])
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