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From: Linus Torvalds <torvalds@osdl.org>
To: Jamie Lokier <jamie@shareable.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	Nikita Danilov <Nikita@Namesys.COM>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-kernel@vger.kernel.org
Subject: Re: const versus __attribute__((const))
Date: Mon, 8 Dec 2003 23:19:36 -0800 (PST)	[thread overview]
Message-ID: <Pine.LNX.4.58.0312082317450.18255@home.osdl.org> (raw)
In-Reply-To: <20031209034935.GA26987@mail.shareable.org>



On Tue, 9 Dec 2003, Jamie Lokier wrote:
>
> (A long time ago there was a question about whether GCC could ever
> copy the value associated with an "m" operand to a stack slot, and
> pass the address of the stack slot.  After all, GCC _will_ copy the
> value if the operand is an "r", and presumably gives mixed results
> with "rm".  We seem to have concluded that it never will).

We never never concluded that they never would, but we did (I think)
convince the gcc people that a memory operand to an asm should always be
considered a lvalue. That will effectively mean that we know a memory op
will never be moved around - because then it wouldn't be the same lvalue
any more (a lvalue is literally defined by its address).

So yes, I think we can depend on it now, although we historically
couldn't.

		Linus

  parent reply	other threads:[~2003-12-09  7:20 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-12-08 15:46 const versus __attribute__((const)) Arnd Bergmann
2003-12-08 17:50 ` H. Peter Anvin
2003-12-08 18:27   ` Nikita Danilov
2003-12-08 18:31     ` H. Peter Anvin
2003-12-09  2:59       ` Jamie Lokier
2003-12-09  3:21         ` H. Peter Anvin
2003-12-09  3:49           ` Jamie Lokier
2003-12-09  5:37             ` H. Peter Anvin
2003-12-09  7:26               ` Linus Torvalds
2003-12-09  7:40                 ` H. Peter Anvin
2003-12-09 11:56                   ` Arnd Bergmann
2003-12-09 15:42                     ` H. Peter Anvin
2003-12-09 16:44                       ` Linus Torvalds
2003-12-09 16:51                         ` H. Peter Anvin
2003-12-09 19:15                           ` Jamie Lokier
2003-12-09  7:19             ` Linus Torvalds [this message]
  -- strict thread matches above, loose matches on Subject: below --
2003-12-08  1:19 H. Peter Anvin
2003-12-08 12:32 ` Nikita Danilov

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