RFR: 8337791: VectorAPI jtreg ABSMaskedByteMaxVectorTests crashes with UseAVX=0 -XX:MaxVectorSize=8 [v9]

[Jatin Bhateja]

> This bug patch fixes a crash seen while querying the bottom type of MachTempNode corresponding to [rxmm0 operand](https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/x86/x86.ad#L22509) of blend pattern during late scheduling. Here, MaxVectorSize is contrainted to 8 bytes thus during C2 type system initialization, [TypeVect::VECTX ](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/type.cpp#L719) guarded by target supprted vector size remains uninitialized.
> 
> Its better to reject matching of VectorBlend in such a scenario.
> 
> All exisitng VectorAPI jtreg tests are passing with -XX:UseAVX=0 and -XX:MaxVectorSize=8
> 
> Kindly review and share your feedback.
> 
> Best Regards,
> Jatin

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

  Update test/hotspot/jtreg/compiler/vectorapi/TestABSMaskedMaxByteVector.java
  
  Co-authored-by: Daniel Lundén <daniel.lunden at oracle.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/28533/files
  - new: https://git.openjdk.org/jdk/pull/28533/files/ef84ffa7..e92cd467

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28533&range=08
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28533&range=07-08

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/28533.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28533/head:pull/28533

PR: https://git.openjdk.org/jdk/pull/28533