Subject: Re: [PATCH 00/10] Add support for GCC's __builtin_unreachable() and use it in BUG.

From: Benjamin Herrenschmidt <[email-masked]>
Date: Thu, 24 Sep 2009 13:37:13 +1000

On Thu, 2009-09-10 at 16:54 -0700, David Daney wrote:
> Starting with version 4.5, GCC has a new built-in function called
> __builtin_unreachable().  The function tells the compiler that control
> flow will never reach that point.  Currently we trick the compiler by
> putting in for(;;); but this has the disadvantage that extra code is
> emitted for an endless loop.  For an i386 kernel using
> __builtin_unreachable() results in an allyesconfig that is nearly 4000
> bytes smaller.

For the powerpc part:

Acked-by: Benjamin Herrenschmidt <[email-masked]>