RFR: 8366588: VectorAPI: Re-intrinsify VectorMask.laneIsSet where the input index is a variable

[erifan]

Intrinsic support for `VectorMask.laneIsSet` with a **variable** input index was introduced in PR #14200, but was inadvertently broken by PR #25673. This PR restores the intrinsic functionality and adds some JTReg tests.

Benchmarks on Nvidia Grace machine with 128-bit SVE:

Benchmark			            Unit	Before		Score Error	After		Score Error	Uplift
microMaskLaneIsSetByte128_var	ops/ms	21702.14415	91.902159	103472.9391	36.057447	4.767867
microMaskLaneIsSetByte64_var	ops/ms	21468.51868	107.94177	103365.6561	69.47736	4.814754
microMaskLaneIsSetDouble128_var	ops/ms	77489.32791	153.242699	413499.4127	311.854079	5.336211
microMaskLaneIsSetFloat128_var	ops/ms	41034.95204	399.421823	206840.0988	74.702234	5.040583
microMaskLaneIsSetFloat64_var	ops/ms	77607.40268	175.938921	413745.3001	149.716794	5.33126
microMaskLaneIsSetInt128_var	ops/ms	41452.48893	76.143208	206845.9754	59.371129	4.989953
microMaskLaneIsSetInt64_var	    ops/ms	77726.2542	173.180518	413427.8838	363.575023	5.319024
microMaskLaneIsSetLong128_var	ops/ms	77646.11218	177.496587	413403.4404	236.609314	5.3242
microMaskLaneIsSetShort128_var	ops/ms	21374.93265	48.13101	103417.4618	34.827021	4.838259
microMaskLaneIsSetShort64_var	ops/ms	41066.19395	353.320621	206801.109	106.408938	5.035799


Benchmarks on Intel 6444y machine with 512-bit avx3:

Benchmark			            Unit	Before		Score Error	After		Score Error	Uplift
microMaskLaneIsSetByte128_var	ops/ms	57658.45497	240.209309	211643.8406	29.214532	3.670647
microMaskLaneIsSetByte256_var	ops/ms	57451.68169	116.994128	211609.4652	160.48513	3.683259
microMaskLaneIsSetByte512_var	ops/ms	57530.22411	311.63868	199802.8084	408.144015	3.473005
microMaskLaneIsSetByte64_var	ops/ms	57642.2672	161.406221	205252.4464	196.86852	3.560797
microMaskLaneIsSetDouble256_var	ops/ms	114401.3789	231.797375	361400.344	565.593984	3.159055
microMaskLaneIsSetDouble512_var	ops/ms	57379.27882	159.699503	211476.1138	136.980026	3.685583
microMaskLaneIsSetFloat128_var	ops/ms	113943.9512	141.062663	360855.3915	494.471996	3.166955
microMaskLaneIsSetFloat256_var	ops/ms	57682.78182	138.142053	211659.5098	30.167972	3.66937
microMaskLaneIsSetFloat512_var	ops/ms	57617.66405	301.748599	211246.8588	597.18949	3.666355
microMaskLaneIsSetInt128_var	ops/ms	113914.5062	118.681382	360856.4465	555.097397	3.167783
microMaskLaneIsSetInt256_var	ops/ms	57681.79883	112.391639	211555.6742	217.556981	3.667633
microMaskLaneIsSetInt512_var	ops/ms	57350.20346	206.146723	211657.7207	68.461571	3.690618
microMaskLaneIsSetLong256_var	ops/ms	113838.3822	415.784529	360782.0645	710.076899	3.169247
microMaskLaneIsSetLong512_var	ops/ms	57314.02695	190.1762	211690.8492	26.47233	3.693526
microMaskLaneIsSetShort128_var	ops/ms	57675.58965	65.940976	211549.9551	276.57545	3.667928
microMaskLaneIsSetShort256_var	ops/ms	57628.8642	91.957833	211694.0864	16.559412	3.673403
microMaskLaneIsSetShort512_var	ops/ms	57845.35211	160.537421	211358.872	660.777147	3.65386
microMaskLaneIsSetShort64_var	ops/ms	113848.8846	222.787418	360294.6295	491.425656	3.164674

-------------

Commit messages:
 - 8366588: VectorAPI: Re-intrinsify VectorMask.laneIsSet where the input index is a variable

Changes: https://git.openjdk.org/jdk/pull/27113/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27113&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8366588
  Stats: 170 lines in 4 files changed: 168 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/27113.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27113/head:pull/27113

PR: https://git.openjdk.org/jdk/pull/27113