RFR: 8273278: Support XSLT on GraalVM Native Image--deterministic bytecode generation in XSLT

[Joe Wang]

On Wed, 1 Sep 2021 13:28:34 GMT, Jovan Stevanovic <github.com+44313413+jovanstevanovic at openjdk.org> wrote:

> GraalVM Native Image supports loading classes at runtime if they are known during image build (class predefinition). This is achieved by the JVMTI agent that registers dynamically generated classes in a regular HotSpot run. The Native Image build uses these registered classes to embed them into the produced binary so they can be loaded at runtime. Loading at runtime is achieved by matching the unique hash of generated classes.
> 
> If the generated bytecode is unstable across runs, the generated native image can not match the hash of the runtime-generated bytecode to the pre-defined classes. The execution failure happens here:
>  https://github.com/oracle/graal/blob/master/substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/hub/PredefinedClassesSupport.java#L127-L131.
> 
> In XSLT the produced bytecode is unstable for the following reasons:
> 
> - Methods like ` HashMap#values` and `HashMap#keySet` result in different traversal orders of its elements yielding a different order of methods and fields.
> 
> - The default `Object#toString` includes the current memory reference of `com.sun.org.apache.xalan.internal.xsltc.compiler.Number` in the generated class.

I'm not involved in any older releases. You'll need to find the right channel for a particular backport you want to make and ask there. As for merging the change in the current release, please update the copyright header and the LastModified date for each of the classes. The github interface unfortunately won't allow me to add comments directly to the unchanged code area. Once that's done, you'll need to issue an integrate command. I'll sponsor your change.

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PR: https://git.openjdk.java.net/jdk/pull/5331