From: Corinna Vinschen <vinschen@redhat.com>
To: newlib@sourceware.org
Subject: Re: [AArch64] Optimized memcmp
Date: Thu, 29 Jun 2017 18:42:00 -0000 [thread overview]
Message-ID: <20170629184233.GZ6201@calimero.vinschen.de> (raw)
In-Reply-To: <AM5PR0802MB261024C52F84B3B42279AFF883D20@AM5PR0802MB2610.eurprd08.prod.outlook.com>
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On Jun 29 14:32, Wilco Dijkstra wrote:
> This is an optimized memcmp for AArch64. This is a complete rewrite
> using a different algorithm. The previous version split into cases
> where both inputs were aligned, the inputs were mutually aligned and
> unaligned using a byte loop. The new version combines all these cases,
> while small inputs of less than 8 bytes are handled separately.
>
> This allows the main code to be sped up using unaligned loads since
> there are now at least 8 bytes to be compared. After the first 8 bytes,
> align the first input. This ensures each iteration does at most one
> unaligned access and mutually aligned inputs behave as aligned.
> After the main loop, process the last 8 bytes using unaligned accesses.
>
> This improves performance of (mutually) aligned cases by 25% and
> unaligned by >500% (yes >6 times faster) on large inputs.
>
> ChangeLog:
> 2017-06-28 Wilco Dijkstra <wdijkstr@arm.com>
>
> * newlib/libc/machine/aarch64/memcmp.S (memcmp):
> Rewrite of optimized memcmp.
Pushed.
Thanks,
Corinna
--
Corinna Vinschen
Cygwin Maintainer
Red Hat
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next prev parent reply other threads:[~2017-06-29 18:42 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-29 14:32 Wilco Dijkstra
2017-06-29 18:42 ` Corinna Vinschen [this message]
2017-08-10 16:16 ` [AArch64] Optimized memcmp (cortex-strings) Wilco Dijkstra
2017-08-10 16:31 ` Corinna Vinschen
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