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

[Benjamin Herrenschmidt]

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 <benh at kernel.crashing.org>