genattrtab.c [Am I on drugs?!?]

[Jeffrey A Law <law at cygnus dot com>]

OK.  I must be on drugs, or we've had this bug lurking for so long it's
scary.

From genattrtab.c::simplify_cond:

  int len = XVECLEN (exp, 0);
  rtunion *tests = (rtunion *) alloca (len * sizeof (rtunion));
  int allsame = 1;
  char *first_spacer;

  /* This lets us free all storage allocated below, if appropriate.  */
  first_spacer = (char *) obstack_finish (rtl_obstack);

  bcopy ((char *) XVEC (exp, 0)->elem, (char *) tests, len * sizeof (rtunion));


XVEXP (exp, 0)->elem is a struct rtx_def *elem[1]  ie a bunch of pointers to
rtxs.

tests is an array of rtunions

rtunion is:

typedef union rtunion_def
{
  HOST_WIDE_INT rtwint;
  int rtint;
  char *rtstr;
  struct rtx_def *rtx;
  struct rtvec_def *rtvec;
  enum machine_mode rttype;
  addr_diff_vec_flags rt_addr_diff_vec_flags;
  struct bitmap_head_def *rtbit;
  union tree_node *rttree;
  struct basic_block_def *bb;
} rtunion;

Note that if sizeof (HOST_WIDE_INT) >= sizeof (pointer), then we lose so
badly it's not funny in the bcopy shown above.

What's scary is I have done significant work with a port over the last two
years where sizeof (HOST_WIDE_INT) >= sizeof (pointer) and this problem never
tripped (until last night).

jeff