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| author | Robin Murphy <robin.murphy@arm.com> | 2018-04-24 16:25:47 +0100 |
|---|---|---|
| committer | celtare21 <celtare21@gmail.com> | 2019-08-27 12:30:09 +0000 |
| commit | a2553e482b92fb7c06f0367e3346f66a8b29deab (patch) | |
| tree | 6cba3b5252faaed2016d2dc3d0741e6451bba4b4 | |
| parent | 176992c0788bd3adc96c0800e3a1ce900c6461b7 (diff) | |
It is probably safe to assume that all Armv8-A implementations have a
multiplier whose efficiency is comparable or better than a sequence of
three or so register-dependent arithmetic instructions. Select
ARCH_HAS_FAST_MULTIPLIER to get ever-so-slightly nicer codegen in the
few dusty old corners which care.
In a contrived benchmark calling hweight64() in a loop, this does indeed
turn out to be a small win overall, with no measurable impact on
Cortex-A57 but about 5% performance improvement on Cortex-A53.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Danny Lin <danny@kdrag0n.dev>
Signed-off-by: celtare21 <celtare21@gmail.com>
| -rw-r--r-- | arch/arm64/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index bd9ee19c43d2..48c8e5697f52 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -6,6 +6,7 @@ config ARM64 select ARCH_CLOCKSOURCE_DATA select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE select ARCH_HAS_ELF_RANDOMIZE + select ARCH_HAS_FAST_MULTIPLIER select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_KCOV select ARCH_HAS_SG_CHAIN |