product(intx, FieldsAllocationStyle, 1, \
"0 - type based with oops first, " \
"1 - with oops last, " \
"2 - oops in super and sub classes are together") \
The current default FieldsAllocationStyle was determined to be most performant, and has been in effect for many years. There is no reason for a user to use this option, and from all reports and google searches, users do not use this option for performance benefit.
This is untested in our test base, and should be deprecated/made obsolete and removed. Doing so would enable efficient rewrite of the field layout code for inline types in valhalla.