RFR: 8352565: Add native method implementation of Reference.get() [v8]
Chen Liang
liach at openjdk.org
Wed Jun 4 17:43:03 UTC 2025
On Wed, 4 Jun 2025 07:12:42 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:
>> Please review this change which adds a native method providing the
>> implementation of Reference::get. Referece::get is an intrinsic candidate, so
>> this native method implementation is only used when the intrinsic is not.
>>
>> Currently there is intrinsic support by the interpreter, C1, C2, and graal,
>> which are always used. With this change we can later remove all the
>> per-platform interpreter intrinsic implementations, and might also remove the
>> C1 intrinsic implementation.
>>
>> Testing:
>> (1) mach5 tier1-6 normal (so using all the existing intrinsics).
>> (2) mach5 tier1-6 with interpreter and C1 Reference::get intrinsics disabled.
>
> Kim Barrett has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 13 additional commits since the last revision:
>
> - Merge branch 'master' into native-reference-get
> - make private native Reference.get0 the intrinsic
> - Merge branch 'master' into native-reference-get
> - Merge branch 'master' into native-reference-get
> - use new waitForRefProc, some tidying
> - Merge branch 'master' into native-reference-get
> - remove timeout by using waitForReferenceProcessing
> - make ill-timed gc in non-concurrent case less likely
> - fix test package use
> - add package decl to test
> - ... and 3 more: https://git.openjdk.org/jdk/compare/8d780d2e...98056a8b
src/hotspot/share/classfile/vmSymbols.hpp line 425:
> 423: template(pc_name, "pc") \
> 424: template(cs_name, "cs") \
> 425: template(get_name, "get") \
A bit surprised that this is not used elsewhere - but as long as this passes compilation I guess this is fine.
src/hotspot/share/interpreter/abstractInterpreter.hpp line 86:
> 84: java_lang_math_fmaF, // implementation of java.lang.Math.fma (x, y, z)
> 85: java_lang_math_fmaD, // implementation of java.lang.Math.fma (x, y, z)
> 86: java_lang_ref_reference_get0, // implementation of java.lang.ref.Reference.get()
Suggestion:
java_lang_ref_reference_get0, // implementation of java.lang.ref.Reference.get()
src/hotspot/share/opto/compile.cpp line 786:
> 784: initial_gvn()->set_type_bottom(s);
> 785: verify_start(s);
> 786: if (method()->intrinsic_id() == vmIntrinsics::_Reference_get) {
Should we remove this now or as part of the redundant intrinsic cleanup for interpreter and c1? I see the interpreter is now kept intact.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/24315#discussion_r2127108041
PR Review Comment: https://git.openjdk.org/jdk/pull/24315#discussion_r2127114784
PR Review Comment: https://git.openjdk.org/jdk/pull/24315#discussion_r2127117794
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