Date: Tue, 16 Mar 1999 00:14:30 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: "Andrew Reilly" <andrew@lake.com.au> Cc: andrew@lake.com.au, sjr@home.net, freebsd-hackers@FreeBSD.ORG Subject: Re: Use of "register" in code Message-ID: <199903160814.AAA06956@apollo.backplane.com> References: <19990316054325.40786.qmail@areilly.bpc-users.org>
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:I've had to use some pretty ordinary compilers. They still exist, and
:are still shipped with new systems.
:
:> specific processor or compiler - usually the VAX. As kernel code started
:> to migrate to other processors, such optimizations have historically
:> produced *WORSE* code on the other processors. So people stopped using
:> 'register' and started expecting compilers to optimize it themselves.
:
:But how is using 'register' with gcc in FreeBSD going to make
:performance _worse_, given that gcc is quite happy to move register
:variables to and from the stack?
:
:I'll shut up now.
:
:--
:Andrew
I doubt it would make performance worse. I think GCC basically just
ignores it for IA32. The general trend in programming these days is
to not use 'register' ( for reasons already outlined ), except in
certain extreme cases. If you are doing small systems work, it's
a different story. But for most mainstream coding 'register' is out.
-Matt
Matthew Dillon
<dillon@backplane.com>
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