RFR: 8256754: Deoptimization::revoke_for_object_deoptimization: stack processing start call is redundant [v2]

[Richard Reingruber]

> This is a XS clean-up of Deoptimization::revoke_for_object_deoptimization() which removes the StackWatermarkSet::start_processing() call.
> 
> This is correct because all paths leading to revoke_for_object_deoptimization() are equipped with a KeepStackGCProcessedMark.
> 
> Call Tree:
> 
> StackWatermarkSet::start_processing(JavaThread *, enum StackWatermarkKind) : void
>     Deoptimization::revoke_for_object_deoptimization(JavaThread *, frame, RegisterMap *, JavaThread *) : void
>         Deoptimization::deoptimize_objects_internal(JavaThread *, GrowableArray<compiledVFrame *> *, bool &) : bool
>             EscapeBarrier::deoptimize_objects_internal(JavaThread *, intptr_t *) : bool
>                 EscapeBarrier::deoptimize_objects_all_threads() : bool                     // has KeepStackGCProcessedMark
>                 EscapeBarrier::deoptimize_objects(intptr_t *) : bool
>                     EscapeBarrier::deoptimize_objects(int, int) : bool                     // has KeepStackGCProcessedMark 
> 
> Testing: hotspot_serviceability, jdk_svc, jdk_jdi, vmTestbase_nsk_jdi, vmTestbase_nsk_jvmti, vmTestbase_nsk_jdwp with -XX:+UseZGC.

Richard Reingruber has updated the pull request incrementally with one additional commit since the last revision:

  Assert stack is kept gc processed.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1381/files
  - new: https://git.openjdk.java.net/jdk/pull/1381/files/f09aaf9b..7f61dbeb

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1381&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1381&range=00-01

  Stats: 21 lines in 4 files changed: 21 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1381.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1381/head:pull/1381

PR: https://git.openjdk.java.net/jdk/pull/1381