"GREngine" (Graph Reachability Engine).  The idea is to provide a separation
of concerns between the constant prop. details and the core analysis engine.

llvm-svn: 45555

llvm-svn: 45554

propagation analysis via graph reachability. This analysis (which is incomplete)
will be the basis for later developments on the core engine for path-sensitive
analysis analysis.

llvm-svn: 45552