[jdk19] RFR: 8288949: serviceability/jvmti/vthread/ContStackDepthTest/ContStackDepthTest.java failing [v4]
Ron Pressler
rpressler at openjdk.org
Wed Jul 6 09:44:23 UTC 2022
> Please review the following bug fix:
>
> `Continuation.enterSpecial` is a generated special nmethod (albeit not a Java method), with a well-known frame layout that calls `Continuation.enter`.
>
> Because it is compiled, it resolves the call to `Continuation.enter` to its compiled version, if available. But this results in the compiled `Continuation.enter` being called even when the thread is in interp_only_mode.
>
> This change does three things:
>
> 1. When entering interp_only_mode, `Continuation::set_cont_fastpath_thread_state` will clear enterSpecial's resolved callsite to Continuation.enter.
> 2. In interp_only_mode, `SharedRuntime::resolve_static_call_C` will return `Continuation.enter`'s c2i entry rather than `verified_code_entry`.
> 3. In interp_only_mode, the c2i stub will not patch the callsite.
>
> This fix isn't perfect, because a different thread, not in interp_only_mode, might patch the call. A longer-term solution is to create an "interpreted" version of `enterSpecial` and supporting an ad-hoc deoptimization. See https://bugs.openjdk.org/browse/JDK-8289128
>
>
> Passes tiers 1-4 and Loom tiers 1-5.
Ron Pressler has updated the pull request incrementally with one additional commit since the last revision:
Changes following review comments
-------------
Changes:
- all: https://git.openjdk.org/jdk19/pull/66/files
- new: https://git.openjdk.org/jdk19/pull/66/files/7323f635..43f18e73
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk19&pr=66&range=03
- incr: https://webrevs.openjdk.org/?repo=jdk19&pr=66&range=02-03
Stats: 5 lines in 2 files changed: 2 ins; 2 del; 1 mod
Patch: https://git.openjdk.org/jdk19/pull/66.diff
Fetch: git fetch https://git.openjdk.org/jdk19 pull/66/head:pull/66
PR: https://git.openjdk.org/jdk19/pull/66
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