How to extract types of variables and its uid?

[Swati Rathi]

We want to store all the types associated with the class objects or 
pointer to a class in a program.

Consider two variables var1 and var2 declared in different functions as 
below.
    class IStream *var1;
    class IStream *var2;

We are extracting its type as below :
    tree type1 = TREE_TYPE (TREE_TYPE (var1));
    tree type2 = TREE_TYPE (TREE_TYPE (var2));

TREE_CODE (type1) and TREE_CODE (type2) is RECORD_TYPE.
We wish to record the type struct IStream.

However, when we print TYPE_UID (type1) and TYPE_UID (type2), it is 
different.
    TYPE_UID = 4326, tree_type : struct IStream
    TYPE_UID = 7421, tree_type : struct IStream

Using TYPE_UID (TYPE_MAIN_VARIANT (type1)) and TYPE_UID 
(TYPE_MAIN_VARIANT (type2)) also gives the same result.

We wish to avoid duplicate entries of the same type.
How to extract types and uid?

Regards,
Swati