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| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2015-10-29 01:16:04 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2015-11-03 14:40:48 +0100 |
| commit | 295d8fa961466bb9e9ebb87b46fdad4edaf736de (patch) | |
| tree | e4a50c47b5520c119bc4bce0f8329057ad707858 /arch/s390 | |
| parent | ccc0e7dc708ce1bd2e1c4a2b6a180ae7459374de (diff) | |
| download | linux-295d8fa961466bb9e9ebb87b46fdad4edaf736de.tar.bz2 | |
s390/Kconfig: use builtin bswap
Depending on the gcc version we can use builtin_bswap instead of
architecture functions. Doing so is better than the inline assembly
version of load reverse for two reasons:
- the sequence of load reversed, apply constant mask, save reversed can
be optimized to load, apply reversed mask, save
- builtins are slightly better to optimize e.g. gcc instruction
scheduler cannot optimize grouping on inline assemblies.
To enable set we have to ARCH_USE_BUILTIN_BSWAP.
bloat-o-meter results:
add/remove: 1/1 grow/shrink: 75/533 up/down: 1711/-9394 (-7683)
Suggested-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 44cb7de499bb..9b9a2db06810 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -101,6 +101,7 @@ config S390 select ARCH_SAVE_PAGE_KEYS if HIBERNATION select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_NUMA_BALANCING + select ARCH_USE_BUILTIN_BSWAP select ARCH_USE_CMPXCHG_LOCKREF select ARCH_WANTS_PROT_NUMA_PROT_NONE select ARCH_WANT_IPC_PARSE_VERSION |