Re: pointer arithmetics and casts

[Al Viro <viro@ftp.linux.org.uk>]

On Fri, May 25, 2007 at 10:23:00PM +0100, Al Viro wrote:
> 	BINOP[+]
> 		<tree for p>
> 		BINOP[*]
> 			IMPLICIEDT_CAST[ptrdiff_t]
> 				<tree for i>
> 			VAL[sizeof(*p)]
> 
> But that means a fsckload of extra nodes allocated on pretty much any
> program - use of arrays is not rare and indices tend to be int, so we
> hit an extra allocated node on each such place.

Argh...  Question: how much do we care if we see BINOP[+] with 64bit
type as result and 32bit type in one of the arguments?  That's what
we get when we have
	char *p;
	int i;

	p + i

with -m64.  IOW, how much does it violate the assumptions outside of
frontend?  We do not allocate any new nodes if sizeof(*p) is 1...