[PATCH 3/3] Optimize 64-bit mpn_add_N and mpn_sub_N for sparc T3 and later.
davem at davemloft.net
Tue Mar 5 20:48:38 CET 2013
From: Richard Henderson <rth at twiddle.net>
Date: Tue, 05 Mar 2013 06:53:18 -0800
> On 03/05/2013 04:54 AM, Torbjorn Granlund wrote:
>> There is currently no mpn/sparc64/ultrasparct3, only ultrasparct1. For
>> which CPUs are these new add_n/sub_n intended? Why not also for for
>> other CPUs?
> For T3 and T4. This file makes use of new instructions: addxc(cc).
> Honestly, why they didn't have a proper 64-bit with carry insn right
> from the very first v9 cpu is a mystery.
Even more mysterious is why, when they finally added it, they didn't
add subxc(cc) as well :-)
We discussed this here back in Dec/Jan when I was working on these
changes, and the sparc cpu folks have already received a complaint,
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