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Re: dangerous cleverness? ppc int<->float conversions, subreg
- To: Zack Weinberg <zack at codesourcery dot com>
- Subject: Re: dangerous cleverness? ppc int<->float conversions, subreg
- From: Richard Henderson <rth at redhat dot com>
- Date: Wed, 24 Oct 2001 14:35:35 -0700
- Cc: gcc at gcc dot gnu dot org
- References: <20011022161325.C29432@codesourcery.com>
On Mon, Oct 22, 2001 at 04:13:25PM -0700, Zack Weinberg wrote:
> I am worried that this trick is _too_ clever and something horrible will
> happen on code which is marginally more complicated than __fixunsdfsi.
I suspect something terrible will happen.
> Note the tree this is being developed in is vintage 2.96-era and does not
> include the SUBREG_BYTE patch, although I may want to roll it forward into
Does the branch include the mode argument to REGISTER_MOVE_COST?
If so, I suspect that you'll get the proper effect from making
the cost of an integer mode in an fp reg equal to MEMORY_MOVE_COST
of the same register. This ought to prevent an fp register from
being preferred, while not actively disallowing it.