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Re: RFC: allowing fwprop to propagate subregs

From: Paolo Bonzini <bonzini at gnu dot org>
To: "H.J. Lu" <hjl dot tools at gmail dot com>, gcc-patches at gcc dot gnu dot org, richard dot sandiford at linaro dot org
Date: Wed, 14 Sep 2011 18:30:56 +0200
Subject: Re: RFC: allowing fwprop to propagate subregs
References: <g439fzi1uv.fsf@richards-thinkpad.stglab.manchester.uk.ibm.com> <CAMe9rOq=zEi2=-Q9CTu77q90+WW4PBpZ7Eo8ZrZJdK3w1YAO-Q@mail.gmail.com> <g439fzqgbj.fsf@richards-thinkpad.stglab.manchester.uk.ibm.com>

On 09/14/2011 05:44 PM, Richard Sandiford wrote:

>  A SUBREG may not be REG nor CONSTANT. Don't you need
>  to check REG_P/CONSTANT_P on SUBREG?


Yeah, good point.  There should be a "&&  REG_P (SUBREG_REG (new_rtx))"
in there.  Probably also worth checking for non-paradoxical subregs.

I was going to suggest the former.

Paradoxical subregs are already handled elsewhere in fwprop, but it also shouldn't hurt to include them.

Paolo

References:
- RFC: allowing fwprop to propagate subregs
  - From: Richard Sandiford
- Re: RFC: allowing fwprop to propagate subregs
  - From: H.J. Lu
- Re: RFC: allowing fwprop to propagate subregs
  - From: Richard Sandiford

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