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Date: Sun, 10 Dec 2000 11:43:33 -0500 (EST)
From: Garrett Wollman <wollman@khavrinen.lcs.mit.edu>
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To: Jeroen Ruigrok van der Werven <asmodai@FreeBSD.org>
Cc: John Baldwin <jhb@FreeBSD.org>, cvs-all@FreeBSD.org,
	cvs-committers@FreeBSD.org
Subject: Re: cvs commit: src/usr.bin/tail forward.c read.c reverse.c tail
In-Reply-To: <20001204202406.A64100@lucifer.bart.nl>
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I hesitate to enter a discussion which has hopefully long since
concluded.  Be that as it may:

<<On Mon, 4 Dec 2000 20:24:06 +0100, Jeroen Ruigrok van der Werven <asmodai@FreeBSD.org> said:

> -On [20001204 20:00], John Baldwin (jhb@FreeBSD.ORG) wrote:
>> They also ignore the register keyword, so this is a rather pointless change,
>> although it does add to repo bloat and in more active code could make diffs
>> harder to read.  :-/

> So effectively the register keyword doesn't serve any purpose anymore
> nowadays.  What would be the point in leaving it in?

Actually, the `register' keyword is *not* ignored by compilers, and
*does* serve a purpose (which may or may not turn out to be useful).
Variables with the `register' storage class may not have their
addresses taken, and the compiler is required to emit a diagnostic if
you try.  The C compiler can not store a variable in a register across
a function call if its address is ever taken.  (This is important for
SPARC processors, but less so on ia32 since there are only two
call-preserved registers.)

-GAWollman



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