Date: Mon, 13 Sep 2004 06:16:40 +0000 From: Dima Dorfman <dd@freebsd.org> To: Giorgos Keramidas <keramida@freebsd.org> Cc: freebsd-bugs@FreeBSD.org Subject: Re: bin/71628: [PATCH] cleanup of the usr.sbin/rpcbind code Message-ID: <20040913061640.GF42003@trit.org> In-Reply-To: <200409130600.i8D60msi015043@freefall.freebsd.org> References: <200409130600.i8D60msi015043@freefall.freebsd.org>
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Giorgos Keramidas <keramida@freebsd.org> wrote:
> On 2004-09-13 02:57, Dan Lukes <dan@obluda.cz> wrote:
> > The unnecesarry initialisation of variable initialised again later
> > seems to be vaste of resources. But IMHO only.
>
> This initialization
>
> char *foo = foo;
>
> is not cheaper than this one:
>
> char *foo = NULL;
To be fair, it could be cheaper because gcc optimizes out the assignment:
dima@beaver% diff -u init-null.s init-self.s
--- init-null.s Mon Sep 13 06:12:05 2004
+++ init-self.s Mon Sep 13 06:12:02 2004
@@ -14,7 +14,6 @@
shrl $4, %eax
sall $4, %eax
subl %eax, %esp
- movl $0, -4(%ebp)
movl $0, %eax
leave
ret
It is likely that I spent more time writing this email than would be
spent executing such an extra instruction in its lifetime.
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