Vector API `lanewise BITWISE_BLEND` on AArch64 is currently lowered to a
generic vector sequence built from `(XorV(AndV(XorV)))` nodes. AArch64
provides a more efficient mapping for this operation through the NEON
`BSL` and SVE `BSL` (bitwise select) instructions.
This change teaches C2 to recognize the `BITWISE_BLEND` patterns and
lower them to the dedicated AArch64 instructions for better performance.
The change includes the AArch64 match rules and assembler support,
updates the AArch64 asm tests, adds IR framework nodes for the new mach
instructions, introduces a new jtreg IR test and extends the
MaskedLogicOpts JMH benchmark for 128-bit long type.
JMH results show **11% - 54%** performance improvements for the
optimized cases, and all jtreg tests (tier1, tier2 and tier3) passe on
SVE2, SVE1, and NEON configurations.
On a Nvidia Grace (Neoverse-V2) machine with 128-bit SVE2:
```
Benchmark Unit ARRAYLEN Before Error After Error Uplift
bitwiseBlendOperationInt128 ops/s 256.00 3787.49 5.29 4277.64 8.89 1.13
bitwiseBlendOperationInt128 ops/s 512.00 1888.24 11.02 2143.21 6.32 1.14
bitwiseBlendOperationInt128 ops/s 1024.00 938.22 6.24 1053.45 14.68 1.12
bitwiseBlendOperationLong128 ops/s 256.00 1895.45 13.68 2140.31 3.68 1.13
bitwiseBlendOperationLong128 ops/s 512.00 938.71 5.32 1052.16 14.07 1.12
bitwiseBlendOperationLong128 ops/s 1024.00 474.15 2.33 526.49 2.62 1.11
```
On an AWS Graviton3 (Neoverse-V1) machine with 256-bit SVE1:
```
Benchmark Unit ARRAYLEN Before Error After Error Uplift
bitwiseBlendOperationInt128 ops/s 256.00 2051.52 13.85 2481.44 0.27 1.21
bitwiseBlendOperationInt128 ops/s 512.00 995.47 20.77 1235.10 5.70 1.24
bitwiseBlendOperationInt128 ops/s 1024.00 507.73 9.83 617.59 2.43 1.22
bitwiseBlendOperationLong128 ops/s 256.00 1000.99 21.50 1235.39 5.48 1.23
bitwiseBlendOperationLong128 ops/s 512.00 507.73 9.74 617.67 2.32 1.22
bitwiseBlendOperationLong128 ops/s 1024.00 258.86 0.01 310.70 0.04 1.20
```
On a Nvidia Grace (Neoverse-V2) machine with 128-bit NEON:
```
Benchmark Unit ARRAYLEN Before Error After Error Uplift
bitwiseBlendOperationInt128 ops/s 256.00 2336.17 13.18 3505.19 19.61 1.50
bitwiseBlendOperationInt128 ops/s 512.00 1145.50 12.40 1735.24 10.43 1.51
bitwiseBlendOperationInt128 ops/s 1024.00 571.41 6.51 866.01 3.34 1.52
bitwiseBlendOperationLong128 ops/s 256.00 1140.38 13.77 1740.28 11.16 1.53
bitwiseBlendOperationLong128 ops/s 512.00 570.20 7.58 865.67 3.33 1.52
bitwiseBlendOperationLong128 ops/s 1024.00 280.94 2.58 432.78 0.19 1.54
```
