On Wed, 26 Aug 2026 18:46:24 GMT, Stefan Karlsson <[email protected]> wrote:
>> The interface on oopDesc and the markWord w.r.t. the locking bits have grown >> overtime the names do not reflect what they actually do, there are multiple >> ways of asking for the same property. >> >> The properties `is_locked` and `is_unlocked` are misleading. As the answer >> true of false does not necessarily reflect the locking state of the object. >> I suggest we use a single terminology `is_fast_locked` to mean the locking >> bits are locked using lightweight non-monitor locking and `is_neutral` to >> mean the locking bits are in the prototype state. >> >> Using `is_fast_unlocked` could be an alternative to `is_neutral`, but >> `is_neutral` captures the state better of being an object which is currently >> not taking part in locking. However the name does not make it obvious that >> it is referring to the locking state / mark state. Not 100% on this naming, >> and how the comments and code which uses these constants in the >> MacroAssembler should name and deal with this. >> >> Also cleaned up the C1 and C2 Valhalla header bits checks which were gated >> on the locking bits. There is not more displaced header so conditionally >> checking the prototype header in the Klass* is not needed. >> >> Testing (in progress): >> * Tier 1-5 Oracle supported platforms >> * GHA >> >> --------- >> - [x] I confirm that I make this contribution in accordance with the >> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). > > src/hotspot/share/opto/graphKit.cpp line 3926: > >> 3924: Node* mark_adr = basic_plus_adr(obj, >> oopDesc::mark_offset_in_bytes()); >> 3925: Node* mark = make_load(nullptr, mark_adr, TypeX_X, >> TypeX_X->basic_type(), MemNode::unordered); >> 3926: if (check_lock && !UseCompactObjectHeaders) { > > I thought we fixed the Valhalla code to check for the object monitor table > here. Maybe this happened in some lworld merge when `UseObjectMonitorTable` was removed. > src/hotspot/share/runtime/synchronizer.cpp line 1789: > >> 1787: >> 1788: markWord mark = object->mark(); >> 1789: assert(mark.is_fast_locked() || mark.has_monitor(), "must be"); > > It's almost like we should have a function named `is_locked()` ... The reason I do not like that is that locking on a monitor is either in the header or in the inflated monitor, which does not belong in `oopDesc`. But I am rewriting this to use `ObjectSynchronizer::current_thread_holds_lock` in the appropriate place. Also folding in the JNI check into the ObjectSynchronizer rather than the callers. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/32544#discussion_r3871500201 PR Review Comment: https://git.openjdk.org/jdk/pull/32544#discussion_r3871523019
