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authorWilco Dijkstra <wdijkstr@arm.com>2020-07-17 14:09:36 +0100
committerWilco Dijkstra <wdijkstr@arm.com>2020-07-17 15:07:23 +0100
commitf46ef33ad134bec7ac992f28ee4b8b0614590e3e (patch)
treef34fe31172e393172c15b2bb189382ad9c0b17e2 /manual
parent76b8442db51a8976de19934638a42532a3af607f (diff)
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AArch64: Improve strlen_asimd performance (bug 25824)
Optimize strlen using a mix of scalar and SIMD code.  On modern micro
architectures large strings are 2.6 times faster than existing
strlen_asimd and 35% faster than the new MTE version of strlen.

On a random strlen benchmark using small sizes the speedup is 7% vs
strlen_asimd and 40% vs the MTE strlen.  This fixes the main strlen
regressions on Cortex-A53 and other cores with a simple Neon unit.

Rename __strlen_generic to __strlen_mte, and select strlen_asimd when
MTE is not enabled (this is waiting on support for a HWCAP_MTE bit).

This fixes big-endian bug 25824. Passes GLIBC regression tests.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
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