Suddenly Android: disable final fields for JIT to get rid of staticFi…

…eldBase/staticFieldOffset
xxDark · Jun 5, 2022 · 6e79544 · 6e79544
1 parent df02091
commit 6e79544
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Showing 2 changed files with 28 additions and 3 deletions.
diff --git a/src/main/java/dev/xdark/ssvm/jit/JitCompiler.java b/src/main/java/dev/xdark/ssvm/jit/JitCompiler.java
@@ -10,6 +10,7 @@
 import dev.xdark.ssvm.mirror.JavaClass;
 import dev.xdark.ssvm.mirror.JavaField;
 import dev.xdark.ssvm.mirror.JavaMethod;
+import dev.xdark.ssvm.util.UnsafeUtil;
 import dev.xdark.ssvm.util.VMHelper;
 import dev.xdark.ssvm.value.DoubleValue;
 import dev.xdark.ssvm.value.FloatValue;
@@ -70,6 +71,7 @@
 @FieldDefaults(level = AccessLevel.PRIVATE, makeFinal = true)
 public final class JitCompiler {
 
+	static final boolean CAN_USE_STATIC_FINAL;
 	private static final AtomicInteger CLASS_ID = new AtomicInteger();
 	private static final ClassType JIT_INVOKER = ClassType.of(JitInvoker.class);
 	private static final ClassType CTX = ClassType.of(ExecutionContext.class);
@@ -318,7 +320,11 @@ public static JitClass compile(JavaMethod jm, int flags) {
 		writer.visitSource(jm.toString(), null);
 		Set<Object> constants = compiler.constants.keySet();
 		if (!constants.isEmpty()) {
-			writer.visitField(ACC_PRIVATE | ACC_STATIC | ACC_FINAL, "constants", "[Ljava/lang/Object;", null, null);
+			int constantsAcc = ACC_PRIVATE | ACC_STATIC;
+			if (CAN_USE_STATIC_FINAL) {
+				constantsAcc |= ACC_FINAL;
+			}
+			writer.visitField(constantsAcc, "constants", "[Ljava/lang/Object;", null, null);
 		}
 
 		byte[] bc = writer.toByteArray();
@@ -1759,6 +1765,19 @@ private static Access getStatic(ClassType owner, String name, ClassType rt) {
 		return new Access(GETSTATIC, owner, name, rt);
 	}
 
+	static {
+		boolean canUseStaticFinal;
+		try {
+			UnsafeUtil.get().staticFieldBase(JitCompiler.class.getDeclaredField("CAN_USE_STATIC_FINAL"));
+			canUseStaticFinal = true;
+		} catch (NoSuchFieldException ex) {
+			throw new ExceptionInInitializerError(ex);
+		} catch (NoSuchMethodError ex) {
+			canUseStaticFinal = false;
+		}
+		CAN_USE_STATIC_FINAL = canUseStaticFinal;
+	}
+
 	private static final class ClassType {
 
 		final Type type;

diff --git a/src/main/java/dev/xdark/ssvm/jit/JitInstaller.java b/src/main/java/dev/xdark/ssvm/jit/JitInstaller.java
@@ -40,8 +40,14 @@ public void install(JavaMethod method, ClassDefiner definer, JitClass jitClass)
 				Class.forName(c.getName(), true, c.getClassLoader());
 			} catch(ClassNotFoundException ignored) {
 			}
-			Unsafe u = UnsafeUtil.get();
-			u.putObject(u.staticFieldBase(field), u.staticFieldOffset(field), constants.toArray());
+			Object[] constantsArray = constants.toArray();
+			if (JitCompiler.CAN_USE_STATIC_FINAL) {
+				Unsafe unsafe = UnsafeUtil.get();
+				unsafe.putObject(unsafe.staticFieldBase(field), unsafe.staticFieldOffset(field), constantsArray);
+			} else {
+				field.setAccessible(true);
+				field.set(null, constantsArray);
+			}
 		}
 		JitInvoker cons = (JitInvoker) c.getConstructor().newInstance();
 		VirtualMachine vm = method.getOwner().getVM();