[jdk17] RFR: 8269568: JVM crashes when running VectorMask query tests [v3]

[Xiaohong Gong]

> This is a follow-up patch for [1]. When we are trying to add the VectorMask query implementation for Arm NEON, we found the jtreg tests for `VectorMask.trueCount/firstTrue/lastTrue` is not effective. The tests failure cannot be reported as expected. The main reason is that the Vector API methods are not hot enough to be compiled by C2 compiler. Wrap the main test codes inside a loop can make the tests effective.
> 
> With the tests taking effect, we can see a JVM crash due to the following assertion:
> 
>   vector/src/hotspot/share/opto/vectornode.hpp:879), pid=168241, tid=168257
>   # Error: assert(mask->Opcode() == Op_VectorStoreMask) failed
> 
> The mask input might be other vector nodes like `"LoadVectorNode"`, since there is an optimization for `"VectorStoreMask"`:
> 
>   VectorStoreMask (VectorLoadMask value) ==> value
> 
> Changing the code to check whether its element basic type is `"T_BOOLEAN"` is more reasonable.
> 
> [1] https://bugs.openjdk.java.net/browse/JDK-8256973

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

  Update x86 fixes and tests to make them cleaner

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

Changes:
  - all: https://git.openjdk.java.net/jdk17/pull/168/files
  - new: https://git.openjdk.java.net/jdk17/pull/168/files/8e3fcfae..4f006a56

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk17&pr=168&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk17&pr=168&range=01-02

  Stats: 245 lines in 33 files changed: 0 ins; 152 del; 93 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/168.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/168/head:pull/168

PR: https://git.openjdk.java.net/jdk17/pull/168