RFR: 8333840: C2 SuperWord: wrong result for MulAddS2I when inputs permuted [v5]

[Emanuel Peter]

> This is an older bug, I discovered it by manual code inspection while refactoring.
> 
> I added some regression tests that produced wrong results.
> 
> You should understand the fix given the comments in the code, if not: tell me how to improve them ;)

Emanuel Peter has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 13 commits:

 - manual merge with master
 - review changes for Vladimir
 - more refactoring
 - improve naming
 - move code
 - rm isa_pack_input_or_null, leave that to a refactoring
 - refactoring / simplification
 - refactor into is_muladds2i_pack_with_pack_inputs
 - fix done, need refactoring
 - more partial fix and more test
 - ... and 3 more: https://git.openjdk.org/jdk/compare/5d2a19de...2155d18b

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

Changes: https://git.openjdk.org/jdk/pull/19619/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19619&range=04
  Stats: 154 lines in 3 files changed: 122 ins; 12 del; 20 mod
  Patch: https://git.openjdk.org/jdk/pull/19619.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19619/head:pull/19619

PR: https://git.openjdk.org/jdk/pull/19619