From: David Miller <davem@davemloft.net>
To: drzeus@drzeus.cx
Cc: netdev@vger.kernel.org
Subject: Re: net: alignment problem in icmp code
Date: Sun, 21 Oct 2007 12:48:14 -0700 (PDT) [thread overview]
Message-ID: <20071021.124814.50617600.davem@davemloft.net> (raw)
In-Reply-To: <20071021113405.37fa0bc5@poseidon.drzeus.cx>
From: Pierre Ossman <drzeus@drzeus.cx>
Date: Sun, 21 Oct 2007 11:34:05 +0200
> Inlining isn't the problem, but the defined semantics of assignment
> versus memcpy(). memcpy() must work on any region of memory, whilst
> assignment must only work on a properly aligned object.
You are missing a crucial point.
The compiler may emit the same exact loads and stores when it inlines
memcpy() if it "knows" the objects are aligned properly. And it very
much will do this.
If the compiler is calling memcpy() in your build, it's only because
gcc believes the the object is too big to optimally memcpy() inline.
next prev parent reply other threads:[~2007-10-21 19:48 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-20 21:35 net: alignment problem in icmp code Pierre Ossman
2007-10-21 5:12 ` David Miller
2007-10-21 9:34 ` Pierre Ossman
2007-10-21 19:48 ` David Miller [this message]
2007-10-21 21:21 ` Pierre Ossman
2007-10-21 23:02 ` David Miller
2007-10-22 4:54 ` Pierre Ossman
2007-10-22 5:15 ` David Miller
2007-10-22 7:23 ` Pierre Ossman
2007-10-22 8:31 ` David Miller
2007-10-22 8:42 ` Pierre Ossman
2007-10-22 9:05 ` David Miller
2007-10-22 9:26 ` Pierre Ossman
2007-10-22 9:52 ` Eric Dumazet
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