RFR: 8288047: Accelerate Poly1305 on x86_64 using AVX512 instructions [v20]

[Volodymyr Paprotski]

On Wed, 16 Nov 2022 23:16:14 GMT, Volodymyr Paprotski <duke at openjdk.org> wrote:

>> src/hotspot/cpu/x86/stubGenerator_x86_64_poly.cpp line 756:
>> 
>>> 754: 
>>> 755:   // Store R^8-R for later use
>>> 756:   __ evmovdquq(Address(rsp, 64*0), B0, Assembler::AVX_512bit);
>> 
>> Could these vector spills be eliminated? I counted 8 spare zmm registers available across the vector loop (xmm7-xmm12, xmm30, xmm31).
>> 
>> And here's what is explicitly used in `process256Loop`:
>> 
>> D0 D1              = xmm2-xmm3
>> B0 B1 B2 B3 B4 B5  = xmm19-xmm24
>> TMP                = xmm6
>> A0 A1 A2 A3 A4 A5  = xmm13-xmm18
>> R0 R1 R2 R1P R2P   = xmm25-xmm29
>> T0 T1 T2 T3 T4 T5  = xmm0-xmm5
>
> Interesting!! Let me try that!

Done!

PS: This find really was great!
PPS: I also reordered the map alphabetically and counted in-order... it was just really bugging me!!

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PR: https://git.openjdk.org/jdk/pull/10582