1 files changed, 57 insertions, 0 deletions
diff --git a/configure.in b/configure.in
index 2185174851..81bc57eeb2 100644
--- a/configure.in
+++ b/configure.in
@@ -1230,6 +1230,63 @@ if test $rb_cv_stack_end_address != no; then
   AC_DEFINE_UNQUOTED(STACK_END_ADDRESS, $rb_cv_stack_end_address)
 fi
 
+AC_CACHE_CHECK(for gc_mark and gc_children stack frame approximate size(word), rb_cv_gc_mark_stackframe_word,
+[save_CFLAGS="$CFLAGS"
+CFLAGS="-O0"
+AC_TRY_RUN([
+int word;
+void *stack_start;
+
+void
+set_stackframe_word()
+{
+    int dumy = 42;
+    int diff;
+
+    if (stack_start < (void *)&dumy) {
+        diff = (int)((void *)&dumy - stack_start);
+    }
+    else {
+        diff = (int)(stack_start - (void *)&dumy);
+    }
+    word = (diff/sizeof(void *));
+    if ((diff % sizeof(void *)) != 0) {
+        word++;
+    }
+}
+
+void
+gc_mark_children(void *p1, void *p2, int lev)
+{
+    void *obj = p2;
+
+    set_stackframe_word(p1,p2,lev);
+}
+
+void
+gc_mark(void *p1, void *p2, int lev)
+{
+    void *obj = p2;
+
+    gc_mark_children(p1,p2,lev++);
+}
+
+int
+main() {
+  int dumy = 42;
+
+  stack_start = (void *)&dumy;
+  gc_mark(0, 0, 255);
+  return word;
+}
+],
+  [rb_cv_gc_mark_stackframe_word="$?"],
+  [rb_cv_gc_mark_stackframe_word="$?"],
+  [rb_cv_gc_mark_stackframe_word="30"])
+CFLAGS="$save_CFLAGS"])
+AC_DEFINE_UNQUOTED(GC_MARK_STACKFRAME_WORD, $rb_cv_gc_mark_stackframe_word)
+
+
 dnl Checks for library functions.
 AC_TYPE_GETGROUPS
 AC_TYPE_SIGNAL