7.2.3 GhostField Attribute

This attribute contains information about a class's ghost fields. The format of the attribute is as follows:

     GhostField_attribute {
       u2 attribute_name_index;
       u4 attribute_length;
       u2 fields_count;
       {
         u2 access_flags;
         u4 BML_flags;
         u2 name_index;
         u2 descriptor_index;
       } fields[fields_count];
     }

The meaning of the fields:

• attribute_name_index - index in the constant pool of the attribute name (org.bmlspecs.GhostField)
• attribute_length - length in bytes of the whole structure
• fields_count - number of entries in the fields table
• fields - the fields table, where each element has the following meaning:
  • access_flags - the flags that are set for the field. The only allowed flags are ACC_PUBLIC, ACC_PROTECTED, ACC_PRIVATE, ACC_FINAL and ACC_STATIC. Only one of ACC_PUBLIC, ACC_PROTECTED, ACC_PRIVATE can be set.
  • BML_flags - the flags that are set for the field. The only allowed flags are BML_NON_NULL, BML_NULLABLE, BML_PEER, BML_REP, BML_READONLY. All other flags must be cleared. Only one of BML_NON_NULL, BML_NULLABLE can be set. Only one of BML_PEER, BML_REP, BML_READONLY can be set.
  • name_index - index in the first or the second constant pool where the field's name is stored
  • descriptor_index - index in the first or the second constant pool where the field's type (possibly \TYPE) is stored

The initial value of a ghost field must be set by a Set instruction in the static initializer (for static ghost fields) and constructors (for instance ghost fields).