Path: utzoo!attcan!uunet!husc6!endor!geoff
From: geoff@endor.harvard.edu (Geoff Clemm)
Newsgroups: comp.lang.c
Subject: Re: The world is not ready for 'volatile'
Message-ID: <903@husc6.harvard.edu>
Date: 3 Jan 89 00:03:38 GMT
References: <141@bms-at.UUCP> <275@twwells.uucp> <15166@mimsy.UUCP> <9236@smoke.BRL.MIL> <15171@mimsy.UUCP>
Sender: news@husc6.harvard.edu
Reply-To: geoff@harvard.harvard.edu (Geoff Clemm)
Organization: Aiken Computation Lab Harvard, Cambridge, MA
Lines: 23

In article <15171@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes:
>>In article <15166@mimsy.UUCP> I suggested that
>>>... ["register"] implies not-volatile and not-aliased; and it does so
>>>in a way that the compiler can reasonably enforce.
>
>In article <9236@smoke.BRL.MIL> gwyn@smoke.BRL.MIL (Doug Gwyn) writes:
>>No, I reject this claim.

I would have to second this rejection.  There is nothing in the
reference manual that lets you count on register variables not being
volatile.

>You mean to say that a register could be aliased?  Not in C!  How
>about a volatile register?  It is a possibility, but it seems entirely
>unnecessary.

Now Chris, this is a total waffle.  For folks that are seriously concerned
about portability, one needs a stronger argument than that "it seems entirely
unnecessary" for a compiler writer to do something -- especially since many
compiler writers ignore register declarations, which means register variables
will be as volatile or non-volatile as any other variable.

Geoff Clemm