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Re: [AArch64] Add precision choices for the reciprocal square root approximation

From: Evandro Menezes <e dot menezes at samsung dot com>
To: Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
Cc: James Greenhalgh <James dot Greenhalgh at arm dot com>, Andrew Pinski <pinskia at gmail dot com>, nd <nd at arm dot com>
Date: Fri, 01 Apr 2016 09:51:55 -0500
Subject: Re: [AArch64] Add precision choices for the reciprocal square root approximation
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References: <56EB2BDC dot 30209 at samsung dot com> <AM3PR08MB00883C48B491A1BA92CD0783838C0 at AM3PR08MB0088 dot eurprd08 dot prod dot outlook dot com> <56EC2A91 dot 2030604 at samsung dot com> <AM3PR08MB0088D90F31B84E852FF3100C838C0 at AM3PR08MB0088 dot eurprd08 dot prod dot outlook dot com> <56EC8870 dot 1030108 at samsung dot com> <56FDA338 dot 4050108 at samsung dot com> <AM3PR08MB00889651F672A4F0157BDE17839A0 at AM3PR08MB0088 dot eurprd08 dot prod dot outlook dot com>

On 04/01/16 08:47, Wilco Dijkstra wrote:

Evandro Menezes wrote:

Ping^1

I haven't seen a newer version that incorporates my feedback. To recap what
I'd like to see is a more general way to select approximations based on mode.
I don't believe that looking at the inner mode works in general, and it doesn't
make sense to add internal tune flags for all possible combinations.

To give an idea what I mean, it would be easiest to add a single field to the CPU
tuning structure that contains a mask for all the combinations. Then we call a
single function with approximation kind ie. sqrt, rsqrt, div (x/y), recip (1/x) and
mode which uses the CPU tuning field to decide whether it should be inlined.


I think that I have a better idea of what you meant.

Thank you,

--
Evandro Menezes

Follow-Ups:
- Re: [AArch64] Add more precision choices for the reciprocal square root approximation
  - From: Evandro Menezes

References:
- Re: [AArch64] Add precision choices for the reciprocal square root approximation
  - From: Wilco Dijkstra

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