As mentioned in the PR, the above reference is about scalar constants, that is not subject to link-params. (Correct me if I am wrong – @dmitriy-arm ).
#8509 is about non-scalar constants.
One option is to hexagon backend needs to be adjusted to handle AllocateConst nodes, instead of LinkedParams node.
Lets continue the discussion on the PR (#8509) to avoid duplicate conversation. Do you agree @kparzysz ?