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Re: [patch] clean up pdp11.md a bit
- From: Richard Henderson <rth at redhat dot com>
- To: Steven Bosscher <stevenb dot gcc at gmail dot com>
- Cc: Paul Koning <paul_koning at dell dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Tue, 14 Feb 2012 14:51:54 -0800
- Subject: Re: [patch] clean up pdp11.md a bit
- References: <CABu31nPp0iY-GDyO8NXdZ3f-_BtU8vVGjAyCRLAvWuD5uVHQuA@mail.gmail.com>
On 02/14/2012 02:08 PM, Steven Bosscher wrote:
> OK for trunk?
This can wait for stage1.
> +;; On PDP-11, DIV always produces a quotient and a remainder. But CSE
> +;; cannot optimize the divmods away because the SET_DESTs are SUBREGs.
> ;(define_expand "divmodhi4"
> ; [(parallel [(set (subreg:HI (match_dup 1) 0)
Which of course begs the question of why that's so.
The division patterns can be modeled similarly to s390.
Indeed, all of the appearances of subreg in the md file are errors:
Should be removed as unnecessary:
Should be removed as generated by generic code: