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Re: Undefined references to 'memcpy' when compiling Linux Kernel
- To: "John Hughes" <john at Calva dot COM>
- Subject: Re: Undefined references to 'memcpy' when compiling Linux Kernel
- From: "Andi Kleen" <ak at suse dot de>
- Date: Mon, 19 Jun 2000 11:27:14 +0200
- Cc: "H . J . Lu" <hjl at lucon dot org>,"Jeff Garzik" <jgarzik at mandrakesoft dot com>,"Byron Stanoszek" <gandalf at winds dot org>,<linux-kernel at vger dot rutgers dot edu>, <alan at lxorguk dot ukuu dot org dot uk>,<gcc at gcc dot gnu dot org>
- References: <20000616155348.A25909@lucon.org> <NCBBLMGKIKDGJMEOMNMEMEEEGOAA.john@Calva.COM>
On Mon, Jun 19, 2000 at 10:14:42AM +0200, John Hughes wrote:
> I don't want to sound dumb; but does anyone know *why* it's not inlining
> the memcpy? It used to.
Inlined memcpy can be very big in some cases, e.g. when gcc cannot
figure out the alignment of the target and destination pointers
at runtime and has to add misalignment handling code. In this case
it is faster to outline to save some L1 cache. gcc 2.96 got new
heuristics for that now.
-Andi