linux-kernel - Re: [PATCH] arch: tile: kernel: kgdb.c: Use memcpy() instead of pointer copy one by one

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Date:	Wed, 12 Nov 2014 15:15:30 -0500
From:	Chris Metcalf <cmetcalf@...hip.com>
To:	Chen Gang <gang.chen.5i5j@...il.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	<jepler@...ythonic.net>
Subject: Re: [PATCH] arch: tile: kernel: kgdb.c: Use memcpy() instead of pointer
 copy one by one

On 11/1/14 21:17, Chen Gang wrote:
> >Not only memcpy() is faster than pointer copy, but also let code more
> >clearer and simple, which can avoid compiling warning (the original
> >implementation copy registers by exceeding member array border).
> >
> >The related warning (with allmodconfig under tile):
> >
> >     CC      arch/tile/kernel/kgdb.o
> >   arch/tile/kernel/kgdb.c: In function 'sleeping_thread_to_gdb_regs':
> >   arch/tile/kernel/kgdb.c:140:31: warning: iteration 53u invokes undefined behavior [-Waggressive-loop-optimizations]
> >      *(ptr++) = thread_regs->regs[reg];
> >                                  ^
> >   arch/tile/kernel/kgdb.c:139:2: note: containing loop
> >     for (reg = 0; reg <= TREG_LAST_GPR; reg++)
> >     ^
> >
> >Signed-off-by: Chen Gang<gang.chen.5i5j@...il.com>
> >---
> >  arch/tile/kernel/kgdb.c | 6 +-----
> >  1 file changed, 1 insertion(+), 5 deletions(-)
> >

Taken into the tile tree - thanks!

See my recent email about changing the shape of the pt_regs and sigcontext
structures to make the regs[] usage explicit.  But even with that, I
think your change makes sense to simplify the code in this location.

-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com

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