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

[PATCH 00/10] Add support for GCC's __builtin_unreachable() and use it in BUG. · David Daney <hidden> · 2009-09-11
[PATCH 07/10] powerpc: Convert BUG() to use unreachable() · David Daney <hidden> · 2009-09-10
[PATCH 01/10] Add support for GCC-4.5's __builtin_unreachable() to compiler.h · David Daney <hidden> · 2009-09-10
Re: [PATCH 01/10] Add support for GCC-4.5's __builtin_unreachable() to compiler.h · Richard Henderson <hidden> · 2009-09-11
Re: [PATCH 01/10] Add support for GCC-4.5's __builtin_unreachable() to compiler.h · Michael Buesch <hidden> · 2009-09-11
Re: [PATCH 01/10] Add support for GCC-4.5's __builtin_unreachable() to compiler.h · David Daney <hidden> · 2009-09-11
Re: [PATCH 01/10] Add support for GCC-4.5's __builtin_unreachable() to compiler.h · Geert Uytterhoeven <geert@linux-m68k.org> · 2009-09-12
Re: [PATCH 01/10] Add support for GCC-4.5's __builtin_unreachable() to compiler.h · David Daney <hidden> · 2009-09-14
Re: [PATCH 00/10] Add support for GCC's __builtin_unreachable() and use it in BUG. · Benjamin Herrenschmidt <benh@kernel.crashing.org> · 2009-09-24

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2009-09-24 03:44:44
Also in: linux-alpha, linux-s390

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@kernel.crashing.org>

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