RFR: 8360599: [TESTBUG] DumpThreadsWithEliminatedLock.java fails because of unstable inlining

[Martin Doerr]

On Sun, 29 Jun 2025 15:26:14 GMT, Richard Reingruber <rrich at openjdk.org> wrote:

> This PR adds CompileCommands to the test DumpThreadsWithEliminatedLock.java to force inlining of java/lang/String*.* methods. This will make inlining more stable to allow for the expected lock elimination based on c2 escape analysis.
> 
> Forcing inlining of java/lang/StringBuffer.* wasn't sufficient on x86_64. With that the test still failed with TieredCompilation disabled.
> 
> Testing: x86_64, ppc64
> 
> Failed inlining on x86_64 with TieredCompilation disabled:
> 
> 
> make test TEST=com/sun/management/HotSpotDiagnosticMXBean/DumpThreadsWithEliminatedLock.java TEST_VM_OPTS="-XX:-TieredCompilation -XX:+UnlockDiagnosticVMOptions -XX:CompileCommand=PrintInlining,DumpThreadsWithEliminatedLock.*" JTREG=TIMEOUT_FACTOR=0.1
> 
> [...]
> 
> STDOUT:
> CompileCommand: PrintInlining DumpThreadsWithEliminatedLock.* bool PrintInlining = true
>                             @ 1   java.util.concurrent.atomic.AtomicBoolean::get (13 bytes)   inline (hot)
>                             @ 11   java.lang.StringBuffer::<init> (7 bytes)   inline (hot)   late inline succeeded (string method)
>                               @ 3   java.lang.AbstractStringBuilder::<init> (39 bytes)   inline (hot)
>                                 @ 1   java.lang.Object::<init> (1 bytes)   inline (hot)
>                             @ 16   java.lang.System::currentTimeMillis (0 bytes)   (intrinsic)
>               s             @ 19   java.lang.StringBuffer::append (13 bytes)   failed to inline: already compiled into a big method
>               s             @ 24   java.lang.StringBuffer::toString (44 bytes)   inline (hot)   late inline succeeded (string method)
>               s               @ 1   java.lang.StringBuffer::length (5 bytes)   accessor
>                               @ 24   java.lang.String::<init> (98 bytes)   failed to inline: already compiled into a big method
>                             @ 30   java.util.concurrent.atomic.AtomicReference::set (6 bytes)   accessor
> 2025-07-02T09:25:53.396634900Z Attempt 1, found: false
> 2025-07-02T09:25:53.415673072Z Attempt 2, found: false
> 2025-07-02T09:25:53.418876867Z Attempt 3, found: false
> 
> [...]

LGTM.

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

Marked as reviewed by mdoerr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26033#pullrequestreview-2978510981