RFR(S) Contended Locking fast exit bucket (8073165)

[Daniel D. Daugherty]

Greetings,

I have the Contended Locking fast exit bucket ready for review.

The code changes in this bucket are primarily assembly language
tweaks that come into play when an inflated ObjectMonitor is in
use. There are tweaks that apply to the default code path and
there are tweaks that only apply when an experimental flag is
set. This code code review is focused on the default code path
or the "out of the box" configuration.

This work is being tracked by the following bug ID:

     JDK-8073165 Contended Locking fast exit bucket
     https://bugs.openjdk.java.net/browse/JDK-8073165

Here is the webrev URL:

http://cr.openjdk.java.net/~dcubed/8073165-webrev/0-jdk9-hs-rt/

Here is the JEP link:

     https://bugs.openjdk.java.net/browse/JDK-8046133

Testing:

- Aurora Adhoc RT/SVC baseline batch
- JPRT test jobs
- MonitorExitStresser micro-benchmark (in process)
- MonitorEnterExitStresser micro-benchmark (in process)
- CallTimerGrid stress testing (in process)
- Aurora performance testing:
   - out of the box for the "promotion" and 32-bit server configs
   - heavy weight monitors for the "promotion" and 32-bit server configs
     (-XX:-UseBiasedLocking -XX:+UseHeavyMonitors)
     (in process)


8073165 summary of changes:

macroAssembler_sparc.cpp: MacroAssembler::compiler_unlock_object()

- default (OOTB) EmitSync value == 0
- an _owner field optimization is in the non-default path under
   a (EmitSync & 1024) check

- classic lock release without 1-0 support is in the non-default
   path under a (EmitSync & 512) check

- an EntryList, cxq and _succ field optimization is in the
   non-default path under a (EmitSync & 16384) check

- the default path is now the 1-0 form that avoids CAS and membar
   in the common case; see the "1-0 exit" section in objectMonitor.cpp

sharedRuntime_sparc.cpp:

- add JavaThread* param for
   SharedRuntime::complete_monitor_unlocking_C call

macroAssembler_x86.cpp: MacroAssembler::fast_unlock()

- with all the new/modified comments and all the optional
   code path updates, it is hard to see that the only real
   changes to the default code path are 1) the _owner==Self
   check has been made optional and 2) the optional succ
   field check for the slow path is now on the default path

- default (OOTB) EmitSync value == 0
- remove optional (EmitSync & 8) code
- refactor code in MacroAssembler::fast_unlock
- remove old mfence() support
- an _owner field optimization is in the non-default path under
   a (EmitSync & 1024) check
- an _owner field optimization is in the non-default path under
   a (EmitSync & 16) check
- a barrier optimization is in the non-default path under a
   (EmitSync & 32) check
- remove old AMD optional work around

sharedRuntime_x86_32.cpp:
sharedRuntime_x86_64.cpp:

- add thread param for SharedRuntime::complete_monitor_unlocking_C
   call

macro.[ch]pp: PhaseMacroExpand::make_slow_call()

- add param2 and update callers

runtime.[ch]pp: OptoRuntime::complete_monitor_exit_Type()

- add JavaThread* parameter

sharedRuntime.[ch]pp: SharedRuntime::complete_monitor_unlocking_C()

- add JavaThread* parameter

synchronizer.cpp: ObjectSynchronizer::omRelease()

- cleanup in use list traversal
- add assert that ObjectMonitor being released was
   actually found and extracted

synchronizer.[ch]pp:

- add some comments in various places
- rename walk_monitor_list() -> deflate_monitor_list()
   and update callers
- minor logic refactoring

thread.hpp:

- add _TSelf field for mfence() replacement


Thanks, in advance, for any comments, questions or suggestions.

Dan