guile-for-guile-emacs/m4/labels-as-values.m4

dnl check for gcc's "labels as values" feature
AC_DEFUN([AC_C_LABELS_AS_VALUES],
[AC_CACHE_CHECK([labels as values], ac_cv_labels_as_values,
[AC_TRY_COMPILE([
int foo(int);
int foo(i)
int i; { 
static void *label[] = { &&l1, &&l2 };
goto *label[i];
l1: return 1;
l2: return 2;
}
],
[int i;], 
ac_cv_labels_as_values=yes,
ac_cv_labels_as_values=no)])
if test "$ac_cv_labels_as_values" = yes; then
AC_DEFINE([HAVE_LABELS_AS_VALUES], [],
          [Define if compiler supports gcc's "labels as values" (aka computed goto)
           feature, used to speed up instruction dispatch in the interpreter.])
fi
])