RFR: 8369435: C2: transform (LShiftX (SubX con0 a), con1) into (SubX con0<<con1 (LShiftX a con1)) [v2]

[Roland Westrelin]

> We already transform:
> 
> (LShiftX (AddX a con0), con1) into (AddX (LShiftX a con1) con0<<con1)
> 
> THis is a variant with SubX. I found that this helps RCE.

Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:

  review

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27842/files
  - new: https://git.openjdk.org/jdk/pull/27842/files/3ab4b313..8b581911

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27842&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27842&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/27842.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27842/head:pull/27842

PR: https://git.openjdk.org/jdk/pull/27842