internal/bytealg: optimize the function compare using SIMD on loong64

internal/bytealg: optimize the function compare using SIMD on loong64

goos: linux
goarch: loong64
pkg: bytes
cpu: Loongson-3A6000-HV @ 2500.00MHz
                  │      old      │                 new                  │
                  │    sec/op     │    sec/op     vs base                │
BytesCompare/1       7.238n ± 25%    5.204n ± 0%  -28.10% (p=0.001 n=10)
BytesCompare/2       7.242n ±  6%    5.204n ± 0%  -28.14% (p=0.000 n=10)
BytesCompare/4       7.229n ±  5%    4.403n ± 0%  -39.10% (p=0.000 n=10)
BytesCompare/8       7.077n ± 36%    4.403n ± 0%  -37.78% (p=0.000 n=10)
BytesCompare/16      8.373n ±  6%    6.004n ± 0%  -28.30% (p=0.000 n=10)
BytesCompare/32      8.040n ±  3%    4.803n ± 0%  -40.26% (p=0.000 n=10)
BytesCompare/64      8.434n ± 24%   10.410n ± 0%  +23.42% (p=0.014 n=10)
BytesCompare/128    11.530n ± 23%    5.604n ± 0%  -51.40% (p=0.000 n=10)
BytesCompare/256    14.180n ±  0%    7.606n ± 0%  -46.36% (p=0.000 n=10)
BytesCompare/512     26.83n ±  0%    10.81n ± 0%  -59.71% (p=0.000 n=10)
BytesCompare/1024    52.60n ±  0%    17.21n ± 0%  -67.28% (p=0.000 n=10)
BytesCompare/2048   103.70n ±  0%    30.02n ± 0%  -71.05% (p=0.000 n=10)
geomean              13.49n          7.607n       -43.63%

goos: linux
goarch: loong64
pkg: bytes
cpu: Loongson-3A6000-HV @ 2500.00MHz
                                      │     old     │                 new                  │
                                      │   sec/op    │    sec/op     vs base                │
CompareBytesEqual                       5.603n ± 0%   5.604n ±  0%        ~ (p=0.191 n=10)
CompareBytesToNil                       3.202n ± 0%   3.202n ±  0%        ~ (p=1.000 n=10)
CompareBytesEmpty                       2.802n ± 0%   2.802n ±  0%        ~ (p=1.000 n=10)
CompareBytesIdentical                   3.202n ± 0%   2.538n ±  1%  -20.72% (p=0.000 n=10)
CompareBytesSameLength                  8.805n ± 0%   4.803n ±  0%  -45.45% (p=0.000 n=10)
CompareBytesDifferentLength             9.206n ± 0%   4.403n ±  0%  -52.17% (p=0.000 n=10)
CompareBytesBigUnaligned/offset=1       82.04µ ± 0%   45.91µ ±  0%  -44.04% (p=0.000 n=10)
CompareBytesBigUnaligned/offset=2       82.04µ ± 0%   45.91µ ±  0%  -44.04% (p=0.000 n=10)
CompareBytesBigUnaligned/offset=3       82.04µ ± 0%   45.91µ ±  0%  -44.04% (p=0.000 n=10)
CompareBytesBigUnaligned/offset=4       82.04µ ± 0%   45.91µ ±  0%  -44.04% (p=0.000 n=10)
CompareBytesBigUnaligned/offset=5       82.04µ ± 0%   45.91µ ±  0%  -44.04% (p=0.000 n=10)
CompareBytesBigUnaligned/offset=6       82.03µ ± 0%   45.93µ ±  0%  -44.01% (p=0.000 n=10)
CompareBytesBigUnaligned/offset=7       82.04µ ± 0%   45.93µ ±  0%  -44.01% (p=0.000 n=10)
CompareBytesBigBothUnaligned/offset=0   78.76µ ± 0%   45.69µ ±  0%  -41.98% (p=0.000 n=10)
CompareBytesBigBothUnaligned/offset=1   85.32µ ± 0%   46.04µ ±  0%  -46.03% (p=0.000 n=10)
CompareBytesBigBothUnaligned/offset=2   85.31µ ± 0%   46.04µ ±  0%  -46.03% (p=0.000 n=10)
CompareBytesBigBothUnaligned/offset=3   85.32µ ± 0%   46.04µ ±  0%  -46.03% (p=0.000 n=10)
CompareBytesBigBothUnaligned/offset=4   85.32µ ± 0%   46.04µ ±  0%  -46.03% (p=0.000 n=10)
CompareBytesBigBothUnaligned/offset=5   85.32µ ± 0%   46.04µ ±  0%  -46.03% (p=0.000 n=10)
CompareBytesBigBothUnaligned/offset=6   85.31µ ± 0%   46.06µ ±  0%  -46.02% (p=0.000 n=10)
CompareBytesBigBothUnaligned/offset=7   85.32µ ± 0%   52.32µ ±  7%  -38.68% (p=0.000 n=10)
CompareBytesBig                         78.76µ ± 0%   50.20µ ±  6%  -36.26% (p=0.000 n=10)
CompareBytesBigIdentical                3.202n ± 0%   3.442n ± 24%        ~ (p=0.462 n=10)
geomean                                 4.197µ        2.630µ        -37.34%

Change-Id: I621145aef3e6a2c68e7127152f26ed047c6b2ece
Reviewed-on: https://go-review.googlesource.com/c/go/+/671315
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
Reviewed-by: Cherry Mui <cherryyz@google.com>