Message-ID: <7ff7c416-fdfe-517f-a65c-9e5bd8ff8cec@linaro.org>
Date: Thu, 1 Dec 2022 17:20:20 +0000
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Subject: Re: [PATCH] Add native windows on arm64 support
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To: Michael Paquier <michael@paquier.xyz>, Andres Freund <andres@anarazel.de>
Cc: Ian Lawrence Barwick <barwick@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>,
 Thomas Munro <thomas.munro@gmail.com>, Julien Rouhaud <rjuju123@gmail.com>,
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From: Niyas Sait <niyas.sait@linaro.org>
In-Reply-To: <Y2ishWF0ZkD2JIpv@paquier.xyz>
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On 07/11/2022 06:58, Michael Paquier wrote:
>>>   #if defined(_WIN64)
>>>   static __forceinline void
>>>   spin_delay(void)
>>>   {
>>> +#ifdef _M_ARM64
>>> +	/*
>>> +	 * arm64 way of hinting processor for spin loops optimisations
>>> +	 * ref: https://community.arm.com/support-forums/f/infrastructure-solutions-forum/48654/ssetoneon-faq
>>> +	*/
>>> +	__isb(_ARM64_BARRIER_SY);
>>> +#else
>>>   	_mm_pause();
>>> +#endif
>>>   }
>>>   #else
>>>   static __forceinline void
>>
>> I think we should just apply this, there seems very little risk of making
>> anything worse, given the gating to _WIN64 && _M_ARM64.
> 
> Seems so.  Hmm, where does _ARM64_BARRIER_SY come from?  Perhaps it
> would be better to have a comment referring to it from a different
> place than the forums of arm, like some actual docs?


_ARM64_BARRIER_SY is defined in Microsoft Arm64 intrinsic documentation 
- 
https://learn.microsoft.com/en-us/cpp/intrinsics/arm64-intrinsics?view=msvc-170#BarrierRestrictions

I couldn't find something more official for the sse2neon library part.

-- 
Niyas