Member predicate GuardedDataFlowNode::getAGuard

Gets an expression that guards this data flow node. That is, this data flow node is only reached when the returned expression has abstract value v.

The expression sub is a sub expression of the guarding expression that is structurally equal to the expression belonging to this data flow node.

In case this data flow node or sub accesses an SSA variable in its left-most qualifier, then so must the other (accessing the same SSA variable).