how can RETURN_ADDR_RTX possibly do its work?

[Nathan Sidwell]

Dave Korn wrote:

  Is there some better solution to this problem that I'm overlooking?  The
rs6000 solution of setting a flag to force the epilog generator to save the
link register whether it thinks it needs to or not seems like the most
robust to me, and I guess it's only a very tiny pessimisation in only those
leaf functions that call __builtin_return_address, but it still seems
inelegant to me.
I found that,

XXX.c
/* The return address of the current function.  */
rtx
XXX_return_addr (void)
{
  return get_hard_reg_initial_val (Pmode, LINK_REGNUM);
}
XXX.h
#define RETURN_ADDR_RTX(count,frame) \
	((count) ? NULL_RTX : XXX_return_addr ())
did the trick. I stole it from one of the other config files, but I forget
which.
nathan
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