implement instanceof

c/execute.c

@@ -1093,7 +1093,20 @@ void op_ineg(struct vm * vm)
 
 void op_instanceof(struct vm * vm, uint32_t index)
 {
-  assert(!"op_instanceof");
+  struct class_entry * class_entry =
+    class_resolver_lookup_class_from_class_index(vm->class_hash_table.length,
+                                                 vm->class_hash_table.entry,
+                                                 vm->current_frame->class_entry,
+                                                 index);
+  assert(class_entry != nullptr);
+
+  int32_t * objectref = (int32_t *)operand_stack_pop_u32(vm->current_frame);
+  if (objectref == nullptr) {
+    operand_stack_push_u32(vm->current_frame, 0);
+  } else {
+    int32_t value = objectref[0] == (int32_t)class_entry;
+    operand_stack_push_u32(vm->current_frame, value);
+  }
 }
 
 void op_invokedynamic(struct vm * vm, uint32_t index)
@@ -1785,6 +1798,7 @@ void op_putfield(struct vm * vm, uint32_t index)
     {
       uint32_t value = operand_stack_pop_u32(vm->current_frame);
       int32_t * objectref = (int32_t *)operand_stack_pop_u32(vm->current_frame);
+      assert(objectref != nullptr);
       int32_t * objectfields = &objectref[1];
       objectfields[field_entry->instance_index] = value;
     }
@@ -1795,6 +1809,7 @@ void op_putfield(struct vm * vm, uint32_t index)
       uint32_t high = operand_stack_pop_u32(vm->current_frame);
       uint32_t low = operand_stack_pop_u32(vm->current_frame);
       int32_t * objectref = (int32_t *)operand_stack_pop_u32(vm->current_frame);
+      assert(objectref != nullptr);
       int32_t * objectfields = &objectref[1];
       objectfields[field_entry->instance_index + 1] = high;
       objectfields[field_entry->instance_index] = low;

p/InstanceOf.java

@@ -0,0 +1,17 @@
+package p;
+
+class ClassA {
+}
+
+class InstanceOf {
+    static boolean test() {
+        ClassA ca = new ClassA();
+        Object a = ca;
+
+        return (ca instanceof ClassA);
+    }
+
+    public static void main() {
+        test();
+    }
+}