High performance BDD package by exploiting memory hierarchy

The success of binary decision diagram (BDD) based algorithms for verification depend on the availability of a high performance package to manipulate very large BDDs. State-of-the-art BDD packages, based on the conventional depth-first technique, limit the size of the BDDs due to a disorderly memory access patterns that results in unacceptably high elapsed time when the BDD size exceeds the main memory capacity. We present a high performance BDD package that enables manipulation of very large BDDs by using an iterative breadth-first technique directed towards localizing the memory accesses to exploit the memory system hierarchy. The new memory-oriented performance features of this package are: 1) an architecture independent customized memory management scheme, 2) the ability to issue multiple independent BDD operations (superscalarity), and 3) the ability to perform multiple BDD operations even when the operands of some BDD operations are the result of some other operations yet to be completed (pipelining). A comprehensive set of BDD manipulation algorithms are implemented using the above techniques. Unlike the breadth-first algorithms presented in the literature, the new package is faster than the state-of-the-art BDD package by a factor of up to 15, even for the BDD sizes that fit within the main memory. For BDD sizes that do not fit within the main memory, a performance improvement of up to a factor of 100 can be achieved.