Reduce the number of VM_isStable messages #21067
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The frontend query `isStable(J9Class *fieldClass, int32_t cpIndex)` determines if the field at given J9Class and cpIndex has the @stable annotation. Before this commit, the JITServer implementation had to send a VM_isStable message to the client for every such query. This commit implements caching of the isStable values at JITServer. Caching is done with a hashtable per J9Class, where the key is the cpIndex we are interested in. To further reduce the number of the hashtables that serve as a cache, the `isStable()` will answer `false` for any non-bootstrap class. The reason is that at the moment only bootstrap classs have the @stable annotation. This behavior can be disabled by defining the following environment variable: `TR_DontIgnoreStableAnnotationForUserClasses`. Another optimization regards the implementation of `isArrayWithStableElements(cpIndex, owningMethod, comp)`. In here, we first check to see if we are dealing with an array (which is simpler) and only then call the isStable() query. Signed-off-by: Marius Pirvu <[email protected]>
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Feb 5, 2025
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jenkins test sanity.functional xlinux,xlinuxjit,plinuxjit,zlinuxjit jdk21 depends eclipse-omr/omr#7642 |
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The frontend query
isStable(J9Class *fieldClass, int32_t cpIndex)determines if the field at given J9Class and cpIndex has the @stable annotation.Before this commit, the JITServer implementation had to send a VM_isStable message to the client for every such query. This commit implements caching of the isStable values at JITServer. Caching is done with a hashtable per J9Class, where the key is the cpIndex we are interested in.
To further reduce the number of the hashtables that serve as a cache, the
isStable()will answerfalsefor any non-bootstrap class. The reason is that at the moment only bootstrap classs have the @stable annotation. This behavior can be disabled by defining the following environment variable:TR_DontIgnoreStableAnnotationForUserClasses.Another optimization regards the implementation of
isArrayWithStableElements(cpIndex, owningMethod, comp). In here, we first check to see if we are dealing with an array (which is simpler) and only then call the isStable() query.Depends on eclipse-omr/omr#7642