Greetings Linus et al.,
From the announcement of the first version:
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 defaultconfig that is
nearly 4000 bytes smaller.
This patch set adds support to compiler.h creating a new macro
usable in the kernel called unreachable(). If the compiler lacks
__builtin_unreachable(), it just expands to for(;;).
For version 2:
I fixed a couple of checkpatch issues, and simplified the
unreachable() macro for the pre-GCC-4.5 case (as suggested by
Richard Henderson). Also several Acked-by: were added.
For this version 2.1:
I removed patches from the set for which there were no Acked-by,
and rebased and tested against 2.6.32.
I will reply with the 5 patches.
David Daney (5):
Add support for GCC-4.5's __builtin_unreachable() to compiler.h (v2)
x86: Convert BUG() to use unreachable()
MIPS: Convert BUG() to use unreachable()
s390: Convert BUG() to use unreachable()
avr32: Convert BUG() to use unreachable()
arch/avr32/include/asm/bug.h | 2 +-
arch/mips/include/asm/bug.h | 4 +---
arch/s390/include/asm/bug.h | 2 +-
arch/x86/include/asm/bug.h | 4 ++--
include/linux/compiler-gcc4.h | 14 ++++++++++++++
include/linux/compiler.h | 5 +++++
6 files changed, 24 insertions(+), 7 deletions(-)
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