This pass implements polymorphic equality.
Details and Notes
For each datatype, tycon, and vector type, it builds and equality function and translates calls to MLton_equal into calls to that function.
Also generates calls to Word_equal.
For tuples, it does the equality test inline; i.e., it does not create a separate equality function for each tuple type.
All equality functions are created only if necessary, i.e., if equality is actually used at a type.
for datatypes that are enumerations, do not build a case dispatch, just use MLton_eq, as the backend will represent these as ints
deep equality always does an MLton_eq test first
If one argument to = is a constant and the type will get translated to an IntOrPointer, then just use eq instead of the full equality. This is important for implementing code like the following efficiently:
if x = 0 ... (* where x is of type IntInf.int *)
Also convert pointer equality on scalar types to type specific primitives.