[cft] subreg validation patch

[Richard Henderson]

On Mon, Nov 15, 2004 at 10:49:06PM +0100, Ulrich Weigand wrote:
> Ah, maybe not: gen_lowpart probably isn't safe here as it may attempt
> to generate new insns.  I think the appropriate thing to use here is
> gen_lowpart_SUBREG.  OK with that change if testing passes?

Hmm.  How about lowpart_subreg?  At least then we won't wind up
with nested subregs.

> Could you elaborate which docs?  I've been studying the 'subreg' section
> in rtl.texi for quite a while, and been a bit frustrated by its attempt
> to define things 'by example' instead of general statements ...

Nope.  On re-reading I don't see any such proscription.  I still
don't think it's a fantastic idea, but...


r~