Espresso: implement knownObjectFieldOffset0 (JDK-8361300)

Author: gilles-duboscq

espresso/src/com.oracle.truffle.espresso/src/com/oracle/truffle/espresso/substitutions/standard/Target_sun_misc_Unsafe.java

@@ -913,6 +913,32 @@ public static long objectFieldOffset1(@JavaType(Unsafe.class) StaticObject self,
         throw meta.throwException(meta.java_lang_InternalError);
     }
 
+    @Substitution(hasReceiver = true, nameProvider = Unsafe11.class)
+    static long knownObjectFieldOffset0(@SuppressWarnings("unused") StaticObject self, @JavaType(Class.class) StaticObject c, @JavaType(String.class) StaticObject guestName,
+                    @Inject Meta meta, @Inject EspressoLanguage language) {
+        // Error code -1 is not found, -2 is static field
+        Klass k = c.getMirrorKlass(meta);
+        if (!(k instanceof ObjectKlass kl)) {
+            return -1;
+        }
+        String hostName = meta.toHostString(guestName);
+        Symbol<Name> name = meta.getNames().lookup(hostName);
+        if (name == null) {
+            return -1;
+        }
+        for (Field f : kl.getFieldTable()) {
+            if (!f.isRemoved() && f.getName() == name) {
+                return getGuestFieldOffset(f, language);
+            }
+        }
+        for (Field f : kl.getStaticFieldTable()) {
+            if (!f.isRemoved() && f.getName() == name) {
+                return -2;
+            }
+        }
+        return -1;
+    }
+
     // region UnsafeAccessors
 
     @GenerateInline