[GR-46507] Support instance main methods (JEP 445)

substratevm/mx.substratevm/mx_substratevm.py

@@ -55,6 +55,7 @@
 
 import sys
 
+
 if sys.version_info[0] < 3:
     from StringIO import StringIO
 else:
@@ -730,13 +731,54 @@ def _cinterfacetutorial(native_image, args=None):
     mx.run([join(build_dir, 'cinterfacetutorial')])
 
 
-def _helloworld(native_image, javac_command, path, build_only, args):
+_helloworld_variants = {
+    'traditional': '''
+public class HelloWorld {
+    public static void main(String[] args) {
+        System.out.println(System.getenv("%s"));
+    }
+}
+''',
+    'noArgs': '''
+// requires JDK 21 and --enable-preview
+public class HelloWorld {
+    static void main() {
+        System.out.println(System.getenv("%s"));
+    }
+}
+''',
+    'instance': '''
+// requires JDK 21 and --enable-preview
+class HelloWorld {
+    void main(String[] args) {
+        System.out.println(System.getenv("%s"));
+    }
+}
+''',
+    'instanceNoArgs': '''
+// requires JDK 21 and --enable-preview
+class HelloWorld {
+    void main() {
+        System.out.println(System.getenv("%s"));
+    }
+}
+''',
+    'unnamedClass': '''
+// requires JDK 21 and javac --enable-preview --source 21 and native-image --enable-preview
+void main() {
+    System.out.println(System.getenv("%s"));
+}
+''',
+}
+
+
+def _helloworld(native_image, javac_command, path, build_only, args, variant=list(_helloworld_variants.keys())[0]):
     mkpath(path)
     hello_file = os.path.join(path, 'HelloWorld.java')
     envkey = 'HELLO_WORLD_MESSAGE'
     output = 'Hello from native-image!'
     with open(hello_file, 'w') as fp:
-        fp.write('public class HelloWorld { public static void main(String[] args) { System.out.println(System.getenv("' + envkey + '")); } }')
+        fp.write(_helloworld_variants[variant] % envkey)
         fp.flush()
     mx.run(javac_command + [hello_file])
 
@@ -1238,20 +1280,26 @@ def _native_image_configure_extra_jvm_args():
 
 def run_helloworld_command(args, config, command_name):
     parser = ArgumentParser(prog='mx ' + command_name)
-    all_args = ['--output-path', '--javac-command', '--build-only']
+    all_args = ['--output-path', '--javac-command', '--build-only', '--variant', '--list']
     masked_args = [_mask(arg, all_args) for arg in args]
+    default_variant = list(_helloworld_variants.keys())[0]
     parser.add_argument(all_args[0], metavar='<output-path>', nargs=1, help='Path of the generated image', default=[svmbuild_dir(suite)])
     parser.add_argument(all_args[1], metavar='<javac-command>', help='A javac command to be used', default=mx.get_jdk().javac)
     parser.add_argument(all_args[2], action='store_true', help='Only build the native image')
+    parser.add_argument(all_args[3], choices=_helloworld_variants.keys(), default=default_variant, help=f'The Hello World source code variant to use (default: {default_variant})')
+    parser.add_argument(all_args[4], action='store_true', help='Print the Hello World source and exit')
     parser.add_argument('image_args', nargs='*', default=[])
     parsed = parser.parse_args(masked_args)
     javac_command = unmask(parsed.javac_command.split())
     output_path = unmask(parsed.output_path)[0]
     build_only = parsed.build_only
     image_args = unmask(parsed.image_args)
+    if parsed.list:
+        mx.log(_helloworld_variants[parsed.variant])
+        return
     native_image_context_run(
         lambda native_image, a:
-        _helloworld(native_image, javac_command, output_path, build_only, a), unmask(image_args),
+        _helloworld(native_image, javac_command, output_path, build_only, a, variant=parsed.variant), unmask(image_args),
         config=config,
     )
 

substratevm/mx.substratevm/testhello.py

@@ -120,11 +120,12 @@ def test():
     # expect "#1  0x[0-9a-f]+ in com.oracle.svm.core.code.IsolateEnterStub.JavaMainWrapper_run_.* at [a-z/]+/JavaMainWrapper.java:[0-9]+"
     exec_string = execute("backtrace")
     stacktraceRegex = [r"#0%shello\.Hello::main%s %s at hello/Hello\.java:77"%(spaces_pattern, param_types_pattern, arg_values_pattern),
-                       r"#1%s%s in com\.oracle\.svm\.core\.JavaMainWrapper::runCore0%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, no_param_types_pattern, no_arg_values_pattern, package_pattern),
-                       r"#2%s%s in com\.oracle\.svm\.core\.JavaMainWrapper::runCore%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, no_param_types_pattern, no_arg_values_pattern, package_pattern),
-                       r"#3%scom\.oracle\.svm\.core\.JavaMainWrapper::doRun%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, param_types_pattern, arg_values_pattern, package_pattern),
-                       r"#4%s(%s in )?com\.oracle\.svm\.core\.JavaMainWrapper::run%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, param_types_pattern, arg_values_pattern, package_pattern),
-                       r"#5%scom\.oracle\.svm\.core\.code\.IsolateEnterStub::JavaMainWrapper_run_%s%s %s"%(spaces_pattern, hex_digits_pattern, param_types_pattern, arg_values_pattern)
+                       r"#1%s%s in com\.oracle\.svm\.core\.JavaMainWrapper::invokeMain%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, param_types_pattern, arg_values_pattern, package_pattern),
+                       r"#2%s(%s in )?com\.oracle\.svm\.core\.JavaMainWrapper::runCore0%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, no_param_types_pattern, no_arg_values_pattern, package_pattern),
+                       r"#3%s%s in com\.oracle\.svm\.core\.JavaMainWrapper::runCore%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, no_param_types_pattern, no_arg_values_pattern, package_pattern),
+                       r"#4%scom\.oracle\.svm\.core\.JavaMainWrapper::doRun%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, param_types_pattern, arg_values_pattern, package_pattern),
+                       r"#5%s(%s in )?com\.oracle\.svm\.core\.JavaMainWrapper::run%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, param_types_pattern, arg_values_pattern, package_pattern),
+                       r"#6%scom\.oracle\.svm\.core\.code\.IsolateEnterStub::JavaMainWrapper_run_%s%s %s"%(spaces_pattern, hex_digits_pattern, param_types_pattern, arg_values_pattern)
                       ]
     if musl:
         # musl has a different entry point - drop the last two frames
@@ -364,11 +365,12 @@ def test():
     exec_string = execute("backtrace")
     stacktraceRegex = [r"#0%shello\.Hello\$Greeter::greeter%s %s at hello/Hello\.java:38"%(spaces_pattern, param_types_pattern, arg_values_pattern),
                        r"#1%s%s in hello\.Hello::main%s %s at hello/Hello\.java:77"%(spaces_pattern, address_pattern, param_types_pattern, arg_values_pattern),
-                       r"#2%s%s in com\.oracle\.svm\.core\.JavaMainWrapper::runCore0%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, no_param_types_pattern, no_arg_values_pattern, package_pattern),
-                       r"#3%s%s in com\.oracle\.svm\.core\.JavaMainWrapper::runCore%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, no_param_types_pattern, no_arg_values_pattern, package_pattern),
-                       r"#4%scom\.oracle\.svm\.core\.JavaMainWrapper::doRun%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, param_types_pattern, arg_values_pattern, package_pattern),
-                       r"#5%s(%s in )?com\.oracle\.svm\.core\.JavaMainWrapper::run%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, param_types_pattern, arg_values_pattern, package_pattern),
-                       r"#6%scom\.oracle\.svm\.core\.code\.IsolateEnterStub::JavaMainWrapper_run_%s%s %s"%(spaces_pattern, hex_digits_pattern, param_types_pattern, arg_values_pattern)
+                       r"#2%s%s in com\.oracle\.svm\.core\.JavaMainWrapper::invokeMain%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, param_types_pattern, arg_values_pattern, package_pattern),
+                       r"#3%s(%s in )?com\.oracle\.svm\.core\.JavaMainWrapper::runCore0%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, no_param_types_pattern, no_arg_values_pattern, package_pattern),
+                       r"#4%s%s in com\.oracle\.svm\.core\.JavaMainWrapper::runCore%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, no_param_types_pattern, no_arg_values_pattern, package_pattern),
+                       r"#5%scom\.oracle\.svm\.core\.JavaMainWrapper::doRun%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, param_types_pattern, arg_values_pattern, package_pattern),
+                       r"#6%s(%s in )?com\.oracle\.svm\.core\.JavaMainWrapper::run%s %s at %sJavaMainWrapper\.java:[0-9]+"%(spaces_pattern, address_pattern, param_types_pattern, arg_values_pattern, package_pattern),
+                       r"#7%scom\.oracle\.svm\.core\.code\.IsolateEnterStub::JavaMainWrapper_run_%s%s %s"%(spaces_pattern, hex_digits_pattern, param_types_pattern, arg_values_pattern)
                       ]
     if musl:
         # musl has a different entry point - drop the last two frames

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/JavaMainWrapper.java

@@ -26,13 +26,17 @@
 
 import java.lang.invoke.MethodHandle;
 import java.lang.invoke.MethodHandles;
+import java.lang.reflect.Constructor;
 import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.function.BooleanSupplier;
 
+import com.oracle.svm.util.ClassUtil;
+import org.graalvm.compiler.serviceprovider.JavaVersionUtil;
 import org.graalvm.compiler.word.Word;
 import org.graalvm.nativeimage.CurrentIsolate;
 import org.graalvm.nativeimage.ImageSingletons;
@@ -74,7 +78,9 @@
 import com.oracle.svm.core.thread.ThreadListenerSupport;
 import com.oracle.svm.core.thread.VMThreads;
 import com.oracle.svm.core.util.CounterSupport;
+import com.oracle.svm.core.util.UserError;
 import com.oracle.svm.core.util.VMError;
+import com.oracle.svm.util.ReflectionUtil;
 
 @InternalVMMethod
 public class JavaMainWrapper {
@@ -92,14 +98,41 @@ public class JavaMainWrapper {
 
     public static class JavaMainSupport {
 
-        public final MethodHandle javaMainHandle;
+        private final MethodHandle javaMainHandle;
+        private final MethodHandle javaMainClassCtorHandle;
         final String javaMainClassName;
 
         public String[] mainArgs;
 
+        private final boolean mainWithoutArgs;
+        private final boolean mainNonstatic;
+
         @Platforms(Platform.HOSTED_ONLY.class)
         public JavaMainSupport(Method javaMainMethod) throws IllegalAccessException {
-            this.javaMainHandle = MethodHandles.lookup().unreflect(javaMainMethod);
+            if (instanceMainMethodSupported()) {
+                javaMainMethod.setAccessible(true);
+                int mods = javaMainMethod.getModifiers();
+                this.mainNonstatic = !Modifier.isStatic(mods);
+                this.mainWithoutArgs = javaMainMethod.getParameterCount() == 0;
+                MethodHandle mainHandle = MethodHandles.lookup().unreflect(javaMainMethod);
+                MethodHandle ctorHandle = null;
+                if (mainNonstatic) {
+                    // Instance main
+                    try {
+                        Constructor<?> ctor = ReflectionUtil.lookupConstructor(javaMainMethod.getDeclaringClass());
+                        ctorHandle = MethodHandles.lookup().unreflectConstructor(ctor);
+                    } catch (ReflectionUtil.ReflectionUtilError ex) {
+                        throw UserError.abort(ex, "No non-private zero argument constructor found in class %s", ClassUtil.getUnqualifiedName(javaMainMethod.getDeclaringClass()));
+                    }
+                }
+                this.javaMainHandle = mainHandle;
+                this.javaMainClassCtorHandle = ctorHandle;
+            } else {
+                this.mainNonstatic = false;
+                this.mainWithoutArgs = false;
+                this.javaMainHandle = MethodHandles.lookup().unreflect(javaMainMethod);
+                this.javaMainClassCtorHandle = null;
+            }
             this.javaMainClassName = javaMainMethod.getDeclaringClass().getName();
         }
 
@@ -129,6 +162,41 @@ public List<String> getInputArguments() {
             }
             return Collections.emptyList();
         }
+
+    }
+
+    public static void invokeMain(String[] args) throws Throwable {
+        JavaMainSupport javaMainSupport = ImageSingletons.lookup(JavaMainSupport.class);
+        if (javaMainSupport.mainNonstatic) {
+            Object instance = javaMainSupport.javaMainClassCtorHandle.invoke();
+            if (javaMainSupport.mainWithoutArgs) {
+                javaMainSupport.javaMainHandle.invoke(instance);
+            } else {
+                javaMainSupport.javaMainHandle.invoke(instance, args);
+            }
+        } else {
+            if (javaMainSupport.mainWithoutArgs) {
+                javaMainSupport.javaMainHandle.invokeExact();
+            } else {
+                javaMainSupport.javaMainHandle.invokeExact(args);
+            }
+        }
+    }
+
+    /**
+     * Determines whether instance main methodes are enabled. See JDK-8306112: Implementation of JEP
+     * 445: Unnamed Classes and Instance Main Methods (Preview).
+     */
+    public static boolean instanceMainMethodSupported() {
+        if (JavaVersionUtil.JAVA_SPEC < 21) {
+            return false;
+        }
+        var previewFeature = ReflectionUtil.lookupClass(true, "jdk.internal.misc.PreviewFeatures");
+        try {
+            return previewFeature != null && (Boolean) previewFeature.getDeclaredMethod("isEnabled").invoke(null);
+        } catch (ReflectiveOperationException e) {
+            throw VMError.shouldNotReachHere(e);
+        }
     }
 
     @Uninterruptible(reason = "The caller initialized the thread state, so the callees do not need to be uninterruptible.", calleeMustBe = false)
@@ -175,7 +243,7 @@ private static int runCore0() {
              * exceptions in a InvocationTargetException.
              */
             JavaMainSupport mainSupport = ImageSingletons.lookup(JavaMainSupport.class);
-            mainSupport.javaMainHandle.invokeExact(mainSupport.mainArgs);
+            invokeMain(mainSupport.mainArgs);
             return 0;
         } catch (Throwable ex) {
             JavaThreads.dispatchUncaughtException(Thread.currentThread(), ex);