RFR [XS]: 8248429: Add --enable-preview as VM argument when running microbenchmarks

[Jorn Vernee]

Forgot to attach the JBS link: 
https://bugs.openjdk.java.net/browse/JDK-8248429

Jorn

On 27/06/2020 00:14, Jorn Vernee wrote:
> Hi,
>
> https://bugs.openjdk.java.net/browse/JDK-8248135 added 
> --enable-preview to the javac options when building micro benchmarks.
>
> We should also add it to the set of default VM arguments passed to the 
> microbenchmark jar so it doesn't need to be passed manually.
>
> If --enable-preview is not passed, the microbenchmarks can not be run 
> (even the ones that don't use preview features). Since the class files 
> have a modified minor version due to building with --enable-preview, 
> the VM must also be started with --enable-preview in order to be able 
> to load the classes. In the absence of --enable-preview, for instance 
> the following error will occur:
>
> java.lang.UnsupportedClassVersionError: Preview features are not 
> enabled for 
> org/openjdk/bench/jdk/incubator/foreign/generated/CallOverhead_panama_args10_jmhTest 
> (class file version 60.65535). Try running with '--enable-preview'
>         at java.base/java.lang.ClassLoader.defineClass1(Native Method)
>         at 
> java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
>         at 
> java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151)
>         at 
> java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:825)
>         at 
> java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:723)
>         at 
> java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:646)
>         at 
> java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:604)
>         at 
> java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:168)
>         at 
> java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
>         at java.base/java.lang.Class.forName0(Native Method)
>         at java.base/java.lang.Class.forName(Class.java:377)
>         at org.openjdk.jmh.util.ClassUtils.loadClass(ClassUtils.java:72)
>         at 
> org.openjdk.jmh.runner.BenchmarkHandler.<init>(BenchmarkHandler.java:68)
>         at 
> org.openjdk.jmh.runner.BaseRunner.runBenchmark(BaseRunner.java:233)
>         at 
> org.openjdk.jmh.runner.BaseRunner.doSingle(BaseRunner.java:139)
>         at 
> org.openjdk.jmh.runner.BaseRunner.runBenchmarksForked(BaseRunner.java:76)
>         at org.openjdk.jmh.runner.ForkedRunner.run(ForkedRunner.java:72)
>         at org.openjdk.jmh.runner.ForkedMain.main(ForkedMain.java:84)
>
>
> Please review the patch attached inline at [1].
>
> Testing: running a microbenchmark without passing '--enable-preview' 
> manually and confirming that it doesn't fail to load the classes.
>
> Thanks,
> Jorn
>
> [1] :
>
> diff --git a/make/RunTests.gmk b/make/RunTests.gmk
> index 721bb827639..59911d89e9f 100644
> --- a/make/RunTests.gmk
> +++ b/make/RunTests.gmk
> @@ -691,7 +691,7 @@ define SetupRunMicroTestBody
>    endif
>
>    # Set library path for native dependencies
> -  $1_JMH_JVM_ARGS := -Djava.library.path=$$(TEST_IMAGE_DIR)/micro/native
> +  $1_JMH_JVM_ARGS := 
> -Djava.library.path=$$(TEST_IMAGE_DIR)/micro/native --enable-preview
>
>    ifneq ($$(MICRO_VM_OPTIONS)$$(MICRO_JAVA_OPTIONS), )
>      $1_JMH_JVM_ARGS += $$(MICRO_VM_OPTIONS) $$(MICRO_JAVA_OPTIONS)
>