src/share/vm/interpreter/rewriter.cpp

rev 8156 : 8157181: Compilers accept modification of final fields outside initializer methods
Summary: Track initialized final field updates; disable constant folding if an update is detected.
Reviewed-by: vlivanov, dnsimon, forax, never, kvn, coleenp

*** 394,407 ****
          case Bytecodes::_invokespecial  : {
            rewrite_invokespecial(bcp, prefix_length+1, reverse, invokespecial_error);
            break;
          }
  
          case Bytecodes::_getstatic      : // fall through
-         case Bytecodes::_putstatic      : // fall through
          case Bytecodes::_getfield       : // fall through
-         case Bytecodes::_putfield       : // fall through
          case Bytecodes::_invokevirtual  : // fall through
          case Bytecodes::_invokestatic   :
          case Bytecodes::_invokeinterface:
          case Bytecodes::_invokehandle   : // if reverse=true
            rewrite_member_reference(bcp, prefix_length+1, reverse);
--- 394,442 ----
          case Bytecodes::_invokespecial  : {
            rewrite_invokespecial(bcp, prefix_length+1, reverse, invokespecial_error);
            break;
          }
  
+         case Bytecodes::_putstatic      :
+         case Bytecodes::_putfield       : {
+           if (!reverse) {
+             // Check if any final field of the class given as parameter is modified
+             // outside of initializer methods of the class. Fields that are modified
+             // are marked with a flag. For marked fields, the compilers do not perform
+             // constant folding (as the field can be changed after initialization).
+             //
+             // The check is performed after verification and only if verification has
+             // succeeded. Therefore, the class is guaranteed to be well-formed.
+             InstanceKlass* klass = method->method_holder();
+             u2 bc_index = Bytes::get_Java_u2(bcp + prefix_length + 1);
+             constantPoolHandle cp(method->constants());
+             Symbol* field_name = cp->name_ref_at(bc_index);
+             Symbol* field_sig = cp->signature_ref_at(bc_index);
+             Symbol* ref_class_name = cp->klass_name_at(cp->klass_ref_index_at(bc_index));
+ 
+             if (klass->name() == ref_class_name) {
+               fieldDescriptor fd;
+               klass->find_field(field_name, field_sig, &fd);
+               if (fd.access_flags().is_final()) {
+                 if (fd.access_flags().is_static()) {
+                   assert(c == Bytecodes::_putstatic, "must be putstatic");
+                   if (!method->is_static_initializer()) {
+                     fd.set_has_initialized_final_update(true);
+                   }
+                 } else {
+                   assert(c == Bytecodes::_putfield, "must be putfield");
+                   if (!method->is_object_initializer()) {
+                     fd.set_has_initialized_final_update(true);
+                   }
+                 }
+               }
+             }
+           }
+         }
+         // fall through
          case Bytecodes::_getstatic      : // fall through
          case Bytecodes::_getfield       : // fall through
          case Bytecodes::_invokevirtual  : // fall through
          case Bytecodes::_invokestatic   :
          case Bytecodes::_invokeinterface:
          case Bytecodes::_invokehandle   : // if reverse=true
            rewrite_member_reference(bcp, prefix_length+1, reverse);