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Re: Is someone working on reg-stack rewrite?
- To: law at cygnus dot com
- Subject: Re: Is someone working on reg-stack rewrite?
- From: Richard Henderson <rth at cygnus dot com>
- Date: Mon, 5 Apr 1999 22:58:53 -0700
- Cc: Jan Hubicka <hubicka at atrey dot karlin dot mff dot cuni dot cz>, egcs at cygnus dot com
- References: <19990405175951.A30941@cygnus.com> <733.923368018@upchuck>
On Mon, Apr 05, 1999 at 09:06:58PM -0600, Jeffrey A Law wrote:
> The basic problem (if I remember right) was that stuff like loading an
> FP register changes the stack. Right?
Yes, the basic problem is that any push or pop operation performs a
copy simultaneously on all existing stacked elements.
> It seems to me the way to handle that is to (internally) show the copies
> that occur due to pushing something on the stack.
>
> Then you can fall back to normal copy motion.
Yeah, well, "normal" copy motion assumes it can manipulate each
register independantly. I'd be delighted to be convinced by example
that normal copy motion will still work when that is not true.
r~