Member predicate GuardedExpr::isGuardedBy
Holds if this expression is guarded by expression cond, which must
evaluate to b. The expression sub is a sub expression of cond
that is structurally equal to this expression.
In case this expression or sub accesses an SSA variable in its
left-most qualifier, then so must the other (accessing the same SSA
variable).
predicate isGuardedBy(Expr cond, Expr sub, boolean b)