There are numerous places within GHC where we use Int to represent a constant literal for the target. For instance, CmmUtils has the following:

-- XXX: should really be Integer, since Int doesn't necessarily cover
-- the full range of target Ints.
mkIntCLit :: DynFlags -> Int -> CmmLit
mkIntCLit dflags i = CmmInt (toInteger i) (wordWidth dflags)

This could go very wrong when cross-compiling from a 32-bit machine to a 64-bit target.