alloca and GC

[Keisuke Nishida]

Hello,

I am wondering if SCM objects stored in alloca'ed memories,
as shown below, are garbage-collected or not.  A preliminary
test showed they aren't:

  scm_bits_t *sp = alloca (100 * sizeof (scm_bits_t));
  sp[0] = SCM_UNPACK (scm_cons (SCM_BOOL_F, SCM_BOOL_F));
  /* sp[0] won't be collected until the end of this function */

Is this true?  Is it safe to store other data than SCM objects
in the allocated memory?  If so, it's convenient for VM stacks.
(BTW, how this works?)

Thanks,
Keisuke Nishida