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Re: [dataflow] partial register handling

From: Richard Sandiford <richard at codesourcery dot com>
To: Paolo Bonzini <bonzini at gnu dot org>
Cc: Kenneth Zadeck <zadeck at naturalbridge dot com>, Roman Zippel <zippel at linux-m68k dot org>, gcc at gcc dot gnu dot org, dberlin at dberlin dot org, Ian Lance Taylor <iant at google dot com>
Date: Sat, 12 May 2007 09:14:29 +0100
Subject: Re: [dataflow] partial register handling
References: <Pine.LNX.4.64.0705101940450.2958@scrub.home> <Pine.LNX.4.64.0705111307140.2958@scrub.home> <4644613C.2000304@naturalbridge.com> <46446E15.2050207@gnu.org>

Paolo Bonzini <bonzini@gnu.org> writes:
> My opinion:
>>> (set (subreg:HI (reg:SI) 2) ...
>>> DF_REF_READ_WRITE?
>
> yep, only case without PARTIAL

Sorry if this is a daft question, but why would it be treated as a read?
I thought that without strict_lowpart, this sort of subreg assignment
was morally equivalent to a normal REG definition in which the upper
bits are "don't care".

Richard

Follow-Ups:
- Re: [dataflow] partial register handling
  - From: Paolo Bonzini

References:
- [dataflow] partial register handling
  - From: Roman Zippel
- Re: [dataflow] partial register handling
  - From: Roman Zippel
- Re: [dataflow] partial register handling
  - From: Kenneth Zadeck
- Re: [dataflow] partial register handling
  - From: Paolo Bonzini

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