RFR: 8308444: LoadStoreNode::result_not_used() is too conservative [v2]

[Quan Anh Mai]

> Hi,
> 
> This patch improves the implementation of `LoadStoreNode::result_not_used()` to be less conservative and verifies that the preferable node is matched for `getAndAdd`. Please kindly review, thanks a lot.

Quan Anh Mai has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains ten commits:

 - fix call node, address reviews
 - Merge branch 'master' into getandadd
 - flag to use imm16
 - Merge branch 'master' into getandadd
 - fix tests
 - fix missing xadds_reg_no_res
 - Merge branch 'master' into getandadd
 - should not ignore blackhole
 - improve GetAndAdd

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Changes: https://git.openjdk.org/jdk/pull/14061/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14061&range=01
  Stats: 279 lines in 6 files changed: 253 ins; 0 del; 26 mod
  Patch: https://git.openjdk.org/jdk/pull/14061.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14061/head:pull/14061

PR: https://git.openjdk.org/jdk/pull/14061