Implement JVM_GetClassFileVersion.

Author: rakachan

espresso-shared/src/com.oracle.truffle.espresso.classfile/src/com/oracle/truffle/espresso/classfile/ClassfileParser.java

@@ -636,7 +636,7 @@ private ParserKlass parseClassImpl() throws ValidationException {
         // Ensure there are no trailing bytes
         stream.checkEndOfFile();
 
-        return new ParserKlass(pool, classFlags, thisKlassName, thisKlassType, superKlass, superInterfaces, methods, fields, attributes, thisKlassIndex, -1);
+        return new ParserKlass(pool, classFlags, thisKlassName, thisKlassType, superKlass, superInterfaces, methods, fields, attributes, thisKlassIndex, majorVersion, minorVersion, -1);
     }
 
     public static Symbol<Name> getClassName(ParsingContext parsingContext, byte[] bytes) throws ValidationException {

espresso-shared/src/com.oracle.truffle.espresso.classfile/src/com/oracle/truffle/espresso/classfile/JavaVersion.java

@@ -77,6 +77,7 @@ public boolean contains(JavaVersion version) {
     public static final JavaVersion HOST_VERSION = forVersion(Runtime.version());
 
     public static final int LATEST_SUPPORTED = 25;
+    public static final int LATEST_SUPPORTED_CLASSFILE = ClassfileParser.JAVA_25_VERSION;
 
     private final int version;
 

espresso-shared/src/com.oracle.truffle.espresso.classfile/src/com/oracle/truffle/espresso/classfile/ParserKlass.java

@@ -59,6 +59,9 @@ public final class ParserKlass {
      */
     private final ParserConstantPool pool;
 
+    private final char majorVersion;
+    private final char minorVersion;
+
     private final int thisKlassIndex;
     private final long hiddenKlassId;
 
@@ -72,7 +75,11 @@ public ParserKlass(ParserConstantPool pool,
                     ParserField[] fields,
                     Attribute[] attributes,
                     int thisKlassIndex,
+                    int majorVersion,
+                    int minorVersion,
                     long hiddenKlassId) {
+        assert majorVersion == (char) majorVersion;
+        assert minorVersion == (char) minorVersion;
         this.pool = pool;
         this.flags = flags;
         this.name = name;
@@ -83,6 +90,8 @@ public ParserKlass(ParserConstantPool pool,
         this.fields = fields;
         this.attributes = attributes;
         this.thisKlassIndex = thisKlassIndex;
+        this.majorVersion = (char) majorVersion;
+        this.minorVersion = (char) minorVersion;
         this.hiddenKlassId = hiddenKlassId;
     }
 
@@ -147,6 +156,14 @@ public long getHiddenKlassId() {
         return hiddenKlassId;
     }
 
+    public int getMajorVersion() {
+        return majorVersion;
+    }
+
+    public int getMinorVersion() {
+        return minorVersion;
+    }
+
     @Override
     public String toString() {
         return "ParserKlass<" + getType() + ">";

espresso/src/com.oracle.truffle.espresso.mokapot/include/mokapot.h

@@ -361,10 +361,7 @@ typedef uint64_t julong;
     /* V(JVM_VirtualThreadUnmountEnd) */ \
     /* Java 20 VM methods */ \
     /* V(JVM_VirtualThreadHideFrames) */ \
-    /* V(JVM_GetClassFileVersion) */ \
-    V(JVM_ScopedValueCache) \
-    V(JVM_SetScopedValueCache) \
-    V(JVM_FindScopedValueBindings) \
+    V(JVM_GetClassFileVersion) \
     /* Java 21 VM Methods */ \
     V(JVM_IsForeignLinkerSupported) \
     /* V(JVM_VirtualThreadStart) */ \
@@ -999,6 +996,8 @@ void (*JVM_ReportFinalizationComplete)(JNIEnv *env, jobject finalizee);
 
 jboolean (*JVM_IsFinalizationEnabled)(JNIEnv *env);
 
+jint (*JVM_GetClassFileVersion)(JNIEnv* env, jclass clazz);
+
 jboolean (*JVM_IsForeignLinkerSupported)(void);
 
 void (*JVM_SleepNanos)(JNIEnv *env, jclass threadClass, jlong nanos);

espresso/src/com.oracle.truffle.espresso.mokapot/src/mokapot.c

@@ -1698,8 +1698,8 @@ JVM_TakeVirtualThreadListToUnblock(JNIEnv* env, jclass ignored) {
 }
 
 JNIEXPORT jint JNICALL JVM_GetClassFileVersion(JNIEnv *env, jclass current) {
-  UNIMPLEMENTED(JVM_GetClassFileVersion);
-  return 0;
+  IMPLEMENTED(JVM_GetClassFileVersion);
+  return (*getEnv())->JVM_GetClassFileVersion(env, current);
 }
 
 JNIEXPORT jboolean JNICALL JVM_IsForeignLinkerSupported(void) {

espresso/src/com.oracle.truffle.espresso/src/com/oracle/truffle/espresso/preinit/ParserKlassProvider.java

@@ -73,7 +73,9 @@ static ParserKlass parseKlass(ClassRegistry.ClassDefinitionInfo info, ClassLoadi
                                 parserKlass.getSuperKlass(), parserKlass.getSuperInterfaces(),
                                 parserKlass.getMethods(), parserKlass.getFields(),
                                 parserKlass.getAttributes(),
-                                parserKlass.getThisKlassIndex(), parserKlass.getHiddenKlassId());
+                                parserKlass.getThisKlassIndex(),
+                                parserKlass.getMajorVersion(), parserKlass.getMinorVersion(),
+                                parserKlass.getHiddenKlassId());
             }
 
             return parserKlass;

espresso/src/com.oracle.truffle.espresso/src/com/oracle/truffle/espresso/vm/VM.java

@@ -89,6 +89,8 @@
 import com.oracle.truffle.espresso.classfile.ConstantPool;
 import com.oracle.truffle.espresso.classfile.Constants;
 import com.oracle.truffle.espresso.classfile.JavaKind;
+import com.oracle.truffle.espresso.classfile.JavaVersion;
+import com.oracle.truffle.espresso.classfile.ParserKlass;
 import com.oracle.truffle.espresso.classfile.attributes.Attribute;
 import com.oracle.truffle.espresso.classfile.attributes.EnclosingMethodAttribute;
 import com.oracle.truffle.espresso.classfile.attributes.InnerClassesAttribute;
@@ -1372,6 +1374,31 @@ public int JVM_GetClassAccessFlags(@JavaType(Class.class) StaticObject clazz) {
         return klass.getModifiers() & Constants.JVM_ACC_WRITTEN_FLAGS;
     }
 
+    @VmImpl(isJni = true)
+    public int JVM_GetClassFileVersion(@JavaType(Class.class) StaticObject clazz, @Inject SubstitutionProfiler profiler) {
+        if (StaticObject.isNull(clazz)) {
+            profiler.profile(0);
+            throw getMeta().throwNullPointerException();
+        }
+        /*
+         * From HotSpot:
+         * 
+         * Return the current class's class file version. The low order 16 bits of the returned jint
+         * contain the class's major version. The high order 16 bits contain the class's minor
+         * version.
+         */
+        Klass klass = clazz.getMirrorKlass(getMeta());
+        if (klass instanceof ObjectKlass objKlass) {
+            profiler.profile(1);
+            ParserKlass parser = objKlass.getLinkedKlass().getParserKlass();
+            return ((parser.getMinorVersion() << 16) | (parser.getMajorVersion()));
+        }
+        profiler.profile(2);
+        // For primitives, return latest (Same as HotSpot).
+        // We do the same for arrays. HotSpot just crashes in that case.
+        return JavaVersion.LATEST_SUPPORTED_CLASSFILE;
+    }
+
     @VmImpl(isJni = true)
     public boolean JVM_AreNestMates(@JavaType(Class.class) StaticObject current, @JavaType(Class.class) StaticObject member) {
         return current.getMirrorKlass(getMeta()).nest() == member.getMirrorKlass(getMeta()).nest();