RFR: 8288303: C1: Miscompilation due to broken Class.getModifiers intrinsic

[Aleksey Shipilev]

Looks like another instance when compilicated control flow in C1 LIR intrinsic confuses the C1 regalloc into miscompiling. Reliably reproduces on selected JFR tests in selected configurations, and I was unable to reproduce it in smaller test.

Additional testing:
 - [x] JFR reproducers now pass
 - [ ] Linux x86_64 fastdebug `tier1`
 - [ ] Linux x86_32 fastdebug `tier1`
 - [ ] Linux x86_64 fastdebug `tier2`
 - [ ] Linux x86_32 fastdebug `tier2`

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Commit messages:
 - Fix
 - Fully branchless version
 - Do stuff without any branches
 - Another fix
 - Fix

Changes: https://git.openjdk.org/jdk19/pull/8/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk19&pr=8&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288303
  Stats: 23 lines in 1 file changed: 12 ins; 5 del; 6 mod
  Patch: https://git.openjdk.org/jdk19/pull/8.diff
  Fetch: git fetch https://git.openjdk.org/jdk19 pull/8/head:pull/8

PR: https://git.openjdk.org/jdk19/pull/8