RFR: 8373724: Assertion failure in TestSignumVector.java with UseAPX [v6]

[Jatin Bhateja]

> Existing demotable instruction patterns for negI/L_rReg_ndd have 'src' as their second operand, this leads to an failure during register biasing. Changing the NDD demotion flags names to encode explicit operand position i.e. **Flag_ndd_demotable_opr1 and Flag_ndd_demotable_opr2** , splitting commutative flag into seperate new flags and fine tuning assertion checks based on new naming convention fixes the issue.
> 
> Failing test test/hotspot/jtreg/compiler/vectorization/TestSignumVector.java passes with the patch.
> 
> Kindly review and share your feedback.
> 
> Best Regards,
> Jatin
> PS: Validation performed using Intel SDE 9.58.

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

  Review comments resolutions

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Changes:
  - all: https://git.openjdk.org/jdk/pull/28999/files
  - new: https://git.openjdk.org/jdk/pull/28999/files/29093665..de6b115c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28999&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28999&range=04-05

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/28999.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28999/head:pull/28999

PR: https://git.openjdk.org/jdk/pull/28999