[vectorIntrinsics] RFR: 8274569: X86 backend related incorrectness issues in legacy store mask patterns [v2]

[Jatin Bhateja]

> - Issue was seen while unit testing changes for masking related optimizations on vectorIntrinsics branch.
> 
> - Following patterns result into incorrect store mask computation, even though contextually store-mask is followed by StoreVector which does takes care of various vector sizes. But C2 does emit VectorStoreMask in IR to populate a byte vector. 
> 
>   - instruct storeMask2B
>   - instruct storeMask4B
>   - instruct storeMask8B
>   - instruct storeMask8B_avx
> 
> - Replicate with immI operand is correctly taking care of shorter vector lengths thus it can be fall back case for following pattern with immediate -1 argument. 
>   - instruct ReplI_M1
>   
> Patch also adds a test case which exhaustively coves load/store vector masks operations for different SPECIES.

Jatin Bhateja has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - 8274569: Fixes for maskquery operations over partial vectors (less than 16 bytes).
 - Merge branch 'vectorIntrinsics' of http://github.com/openjdk/panama-vector into JDK-8274569
 - 8274569: X86 backend related incorrectness issues in legacy storemask patterns

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

Changes:
  - all: https://git.openjdk.java.net/panama-vector/pull/139/files
  - new: https://git.openjdk.java.net/panama-vector/pull/139/files/8f1ad547..e03a41c3

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=139&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=139&range=00-01

  Stats: 9015 lines in 310 files changed: 6265 ins; 1561 del; 1189 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/139.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/139/head:pull/139

PR: https://git.openjdk.java.net/panama-vector/pull/139