RFR: 8302906: AArch64: Add SVE backend support for vector unsigned comparison [v3]

[changpeng1997]

> This patch implements unsigned vector comparison on SVE.
> 
> 1: Test:
> All vector API test cases[1][2] passed without new failure. Existing test cases can cover all unsigned comparison conditions for all kinds of vector.
> 
> 2: Performance:
> (1): Benchmark:
> As existing benchmarks in panama repo (such as [3]) have some issues [4] (We will fix them in a separate patch.), I collected performance data with a reduced jmh benchmark [5]. e.g. for ByteVector unsigned comparison:
> 
> 
> @Benchmark
>     public void byteVectorUnsignedCompare() {
>         for (int j = 0; j < 200; j++) {
>             for (int i = 0; i < bspecies.length(); i++) {
>                 ByteVector av = ByteVector.fromArray(bspecies, ba, i);
>                 ByteVector ca = ByteVector.fromArray(bspecies, bb, i);
>                 av.compare(VectorOperators.UNSIGNED_GT, ca).intoArray(br, i);
>             }
>         }
>     }
> 
> 
> (2): Performance data
> 
> Before:
> 
> 
> Benchmark                               Score(op/ms)     Error
> ByteVector.UNSIGNED_GT#size(1024)       4.846            3.419
> ShortVector.UNSIGNED_GE#size(1024)      3.055            1.369
> IntVector.UNSIGNED_LT#size(1024)        3.475            1.269
> LongVector.UNSIGNED_LE#size(1024)       4.515            1.812
> 
> 
> After:
> 
> 
> Benchmark                               Score(op/ms)     Error
> ByteVector.UNSIGNED_GT#size(1024)       493.937          1.389
> ShortVector.UNSIGNED_GE#size(1024)      5308.796         20.557
> IntVector.UNSIGNED_LT#size(1024)        4944.744         10.606
> LongVector.UNSIGNED_LE#size(1024)       8459.605         28.683
> 
> 
> [1] https://github.com/openjdk/jdk/tree/master/test/jdk/jdk/incubator/vector
> [2] https://github.com/openjdk/jdk/tree/master/test/hotspot/jtreg/compiler/vectorapi
> [3] https://github.com/openjdk/panama-vector/blob/2aade73adeabdf6a924136b17fd96ccc95c1d160/test/micro/org/openjdk/bench/jdk/incubator/vector/operation/ByteMaxVector.java#L1459
> [4] https://bugs.openjdk.org/browse/JDK-8282850
> [5] https://gist.github.com/changpeng1997/d311127e1015c107197f9b56a92b0fae

changpeng1997 has updated the pull request incrementally with one additional commit since the last revision:

  Refactor part of code in C2 assembler and remove some switch-case stmts.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/12725/files
  - new: https://git.openjdk.org/jdk/pull/12725/files/d210ae92..5acf5ba4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12725&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12725&range=01-02

  Stats: 263 lines in 8 files changed: 92 ins; 63 del; 108 mod
  Patch: https://git.openjdk.org/jdk/pull/12725.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12725/head:pull/12725

PR: https://git.openjdk.org/jdk/pull/12725