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Re: RFC: bug in combine

From: Florian Weimer <fw at deneb dot enyo dot de>
To: Dale Johannesen <dalej at apple dot com>
Cc: gcc mailing list <gcc at gcc dot gnu dot org>
Date: Thu, 25 Aug 2005 20:19:11 +0200
Subject: Re: RFC: bug in combine
References: <892d2a3b1deb45d0cb883c2df201e084@apple.com><87acj5rikk.fsf@mid.deneb.enyo.de>

* Florian Weimer:

> * Dale Johannesen:
>
>> The test of f->b comes out as
>>
>>   testl  $1048512, 73(%eax)
>>
>> This is wrong, because 4 bytes starting at 73 goes outside the
>> original object and can cause a page fault.
>
> sizeof (struct Flags) is 76, so this isn't a bug, IMHO.

Scratch that, I obviously cannot count. 8-(

Anyway, why is GCC emitting an unaligned load?  This is very strange
indeed, and fixing this should both increase code quality and
eliminate the page fault problem.

References:
- RFC: bug in combine
  - From: Dale Johannesen
- Re: RFC: bug in combine
  - From: Florian Weimer

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