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Re: Use of register 17 on x86
- To: Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>
- Subject: Re: Use of register 17 on x86
- From: Richard Henderson <rth at redhat dot com>
- Date: Sun, 18 Feb 2001 15:45:54 -0800
- Cc: gcc at gcc dot gnu dot org
- References: <10102182326.AA15117@vlsi1.ultra.nyu.edu>
On Sun, Feb 18, 2001 at 06:26:08PM -0500, Richard Kenner wrote:
> Maybe, but the downside is that you have the explicit clobber of the register
> in many arithmetic insns, making it harder to optimize them because you
> can't just insert one without knowing if reg 17 is dead there.
Yep. In local optimizations, it's easy enough to work around this.
Global opts do present a problem -- this is one of the reasons why
having multiple levels of IL is a good idea.
r~