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Re: [dataflow] partial register handling

From: Paolo Bonzini <bonzini at gnu dot org>
To: Kenneth Zadeck <zadeck at naturalbridge dot com>
Cc: 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: Fri, 11 May 2007 15:22:29 +0200
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>

My opinion:

(set (subreg:SI (reg:DI) 4) ...
DF_REF_READ_WRITE|DF_REF_PARTIAL?

yep

(set (subreg:HI (reg:DI) 6) ...
DF_REF_READ_WRITE?

Also PARTIAL. you can rely on the content of the 0-3 word.

Likewise for:

(set (subreg:HI (reg:DI) 2) ...

here you can rely on the content of the 4-7 word.

(set (subreg:HI (reg:SI) 2) ...
DF_REF_READ_WRITE?

yep, only case without PARTIAL

(set (strict_low_part (subreg:HI (reg:DI) 6)) ...
DF_REF_READ_WRITE|DF_REF_PARTIAL?

yep

(set (strict_low_part (subreg:HI (reg:SI) 2)) ...
DF_REF_READ_WRITE|DF_REF_PARTIAL?

yep

(set (zero_extract:SI (reg:SI) (const_int 16) (const_int 16)) ...)
DF_REF_READ_WRITE|DF_REF_PARTIAL?

yep

Follow-Ups:
- Re: [dataflow] partial register handling
  - From: Richard Sandiford

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

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