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Re: [RFC 1/5] Lazy register values
- From: Daniel Jacobowitz <drow at false dot org>
- To: Ulrich Weigand <uweigand at de dot ibm dot com>
- Cc: gdb-patches at sourceware dot org
- Date: Fri, 4 Apr 2008 15:28:59 -0400
- Subject: Re: [RFC 1/5] Lazy register values
- References: <20080331220656.GA22012@caradoc.them.org> <200804041917.m34JHcNk029476@d12av02.megacenter.de.ibm.com>
On Fri, Apr 04, 2008 at 09:17:38PM +0200, Ulrich Weigand wrote:
> I like this approach! However, I'm wondering about some of the
> value_lazy changes; for example in code like:
> v = allocate_value (elt_type);
> if (value_lazy (array))
> set_value_lazy (v, 1);
> memcpy (value_contents_writeable (v),
> value_contents (array) + elt_offs, elt_size);
> (in value_subscripted_rvalue), it doesn't seem right to simply
> change the if to
> if (VALUE_LVAL (array) == lval_memory && value_lazy (array))
> If that function were ever called with a lazy register value,
> the "else" part would copy from value_contents of that lazy
> value, which is actually undefined.
I don't think that's what happens - value_contents ->
value_contents_writeable -> value_fetch_lazy. I figured the fetch at
this point was acceptable; we work hard to avoid fetching memory
because it might be large, but registers are better bounded.
Do you agree, or are the offsets worthwhile after all?
> I've read through the rest of the patches in this series,
> and they look fine to me. I'd be happy to convert any of
> the platforms I have access to (s390, ppc, spu, ia64).
My plan is to wait until at least next week, in case anyone else
has comments; revise for comments; do as many other platforms as
I can test; and then start checking this in. I'll fix any other
platforms I'm asked to. I don't expect any substantial revisions,
in case you feel like getting a head start :-)