m4/ac_have_builtin_expect.m4

   1 AC_DEFUN([AX_C___BUILTIN_EXPECT], [
   2   AC_MSG_CHECKING(for __builtin_expect)
   3   AC_CACHE_VAL(ac_cv___builtin_expect, [
   4     AC_TRY_COMPILE(
   5       [int foo(void) { if (__builtin_expect(0, 0)) return 1; return 0; }],
   6       [],
   7       ac_cv___builtin_expect=yes,
   8       ac_cv___builtin_expect=no
   9     )])
  10   if test "$ac_cv___builtin_expect" = "yes"; then
  11     AC_DEFINE(HAVE___BUILTIN_EXPECT, 1, [define if your compiler has __builtin_expect])
  12   fi
  13   AC_MSG_RESULT($ac_cv___builtin_expect)
  14 ])