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From: kenner@lab.ultra.nyu.edu (Richard Kenner)
Subject: Re: Releasing Aliased Variables
Date: Mon, 12 Mar 2001 18:45:23 GMT
Date: 2001-03-12T18:45:23+00:00	[thread overview]
Message-ID: <7P8r6.16$Pa3.362@typhoon.nyu.edu> (raw)
In-Reply-To: 87bsrcs8a3.fsf@deneb.enyo.de

In article <87bsrcs8a3.fsf@deneb.enyo.de> Florian Weimer <fw@deneb.enyo.de> writes:
>Some time ago, there was a thread in which someone explained (I think
>Robert Dewar) that 'aliased' does not provide any help to the compiler
>regarding alias detection, register allocation etc. because the
>compiler has to be able to determine this kind of information anyway
>if an Address attribute is used.
>
>So in code-generation terms, 'aliased' is a no-op.

That's not completely true.  It has at least two effects:

(1) An aliased component of an aggregate must be on the same alignment
boundary as its type, which affects packing in records and allowable
record rep clauses.

(2) If you have a de-reference through an access type for some type
and you have a field of an aggregate that is of that type, you know
that the reference *cannot* be to that field.



  parent reply	other threads:[~2001-03-12 18:45 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-03-07 19:57 Releasing Aliased Variables Byron Kauffman
2001-03-07 20:44 ` tmoran
2001-03-07 21:12 ` Robert A Duff
2001-03-08 13:24   ` Florian Weimer
2001-03-08 14:37     ` Pat Rogers
2001-12-27 12:26       ` Florian Weimer
2001-03-08 14:52     ` Tucker Taft
2001-03-08 16:57     ` Robert A Duff
2001-03-09 15:08       ` Using COM Interfaces (was: Releasing Aliased Variables) Byron Kauffman
2001-03-09 17:01         ` Robert A Duff
2001-03-09 21:08         ` tmoran
2001-03-12 18:45     ` Richard Kenner [this message]
2001-03-07 21:31 ` Releasing Aliased Variables Florian Weimer
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