The float_regs pass did not consider this possibility: a term being
deconstructed can have a ground inst with no higher-order inst
information, but higher-order inst information is still available for
the sub-unifications of the term's arguments. This is possible with the
introduction of the "combined higher-order types and insts" feature.
Losing the higher-order inst information led to an exception:
Unexpected: no higher order inst
compiler/float_regs.m:
Handle the case above in unify_mode_set_rhs_final_inst.
Minor improvements in comments.
tests/hard_coded/Mmakefile:
tests/hard_coded/functor_ho_inst_float_reg.exp:
tests/hard_coded/functor_ho_inst_float_reg.m:
Add test case.
