when they are destroyed, which makes Constant::destroyConstant an actually
useful external interface. Expose these methods publicly.
- Implement destroyConstant on ConstPointerNull so that destroyConstant can
be used on any derived type constant safely.
llvm-svn: 3378
Note that a ConstantExpr can be of any type, so classof() in most
other subclasses (that discriminate by type) have to check that it
is also not a ConstantExpr. This is why isConstantExpr() is needed.
llvm-svn: 2890
