Add support for GCC's __builtin_unreachable() and use it in BUG (v2.1).
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Patches in v1 No applies recorded yet
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/5 | Add support for GCC-4.5's __builtin_unreachable() to compiler.h (v2)include/ include/ | +19 | 0 replies | |
| 2/5 | x86: Convert BUG() to use unreachable()arch/ | +2 | 0 replies | |
| 3/5 | MIPS: Convert BUG() to use unreachable()arch/ | +1 | 0 replies | |
| 4/5 | s390: Convert BUG() to use unreachable()arch/ | +1 | 0 replies | |
| 5/5 | avr32: Convert BUG() to use unreachable()arch/ | +1 | 0 replies |
Reviews trailers per patch
All 5 patches have a Reviewed-by or Acked-by.
| Patch | Ralf Baechle | Martin Schwidefsky | Haavard Skinnemoen | H. Peter Anvin |
|---|---|---|---|---|
| 1/5 | A-b | |||
| 2/5 | A-b | |||
| 3/5 | A-b | |||
| 4/5 | A-b | |||
| 5/5 | A-b |
Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes. Scroll the table sideways for all 4 reviewers.
Cover letter [PATCH 0/5] Add support for GCC's __builtin_unreachable() and use it in BUG (v2.1).
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(-)