RFR: 8344355: Register corruption in MacroAssembler::lookup_secondary_supers_table_var: x86-64 only [v2]

[Andrew Haley]

> This bug only affects x86-64 machines without a `popcnt` instruction, which basically means pre-SSE4.2 machines. This means that x86-64 processors made around 2010 are affected.
> 
> My thanks to everyone who was was involved in bisecting this, particularly Martin Bucholz who seems to be the only one testing on such old hardware.

Andrew Haley has updated the pull request incrementally with one additional commit since the last revision:

  8344355: Register corruption in MacroAssembler::lookup_secondary_supers_table_var: x86-64 only

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22365/files
  - new: https://git.openjdk.org/jdk/pull/22365/files/dd2d4b5a..9a2b581e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22365&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22365&range=00-01

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22365.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22365/head:pull/22365

PR: https://git.openjdk.org/jdk/pull/22365