[PATCH] arm64: Select ARCH_HAS_FAST_MULTIPLIER

[Will Deacon]

On Tue, Apr 24, 2018 at 04:25:47PM +0100, Robin Murphy wrote:
> 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.
> 
> Signed-off-by: Robin Murphy <robin.murphy at arm.com>
> ---

Acked-by: Will Deacon <will.deacon at arm.com>

Will