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Re: Incorrect bitfield aliasing with Tree SSA

From: Eric Botcazou <ebotcazou at libertysurf dot fr>
To: Adam Nemet <anemet at caviumnetworks dot com>
Cc: gcc-patches at gcc dot gnu dot org, "Daniel Berlin" <dberlin at dberlin dot org>, "Richard Kenner" <kenner at vlsi1 dot ultra dot nyu dot edu>
Date: Mon, 18 Jun 2007 10:28:01 +0200
Subject: Re: Incorrect bitfield aliasing with Tree SSA
References: <18034.48960.772642.116034@localhost.localdomain> <4aca3dc20706171302g4f4c3d41i1ba6288540ad4597@mail.gmail.com> <18037.47847.601418.214255@localhost.localdomain>

> Wouldn't this be as simple as assigning the type of
> DECL_NONADDRESSABLE_P fields to a different alias set than the alias
> set of the type.  Subset this alias set with that of its parent.  This
> alias set would still conflict with anybody potentially referencing
> the parent (which would fix the bitfield issue) but would not conflict
> with the alias set of the type of the field (which is what the Ada
> folks are after)?

Yes, I also agree that this should work.  Now replace "a different alias set 
than the alias set of the type" by "the alias set of its parent" in the above 
paragraph; everything remains valid.  So why do we need another alias set?

-- 
Eric Botcazou

Follow-Ups:
- Re: Incorrect bitfield aliasing with Tree SSA
  - From: Daniel Berlin

References:
- Re: Incorrect bitfield aliasing with Tree SSA
  - From: Daniel Berlin
- Re: Incorrect bitfield aliasing with Tree SSA
  - From: Adam Nemet

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