Arguments reach_in_exported_tgt {b m args} j _.

Lemma extern_semantics_preservation c c' d m m' tm cd j ef sig args :
trace_match_state cd j c m d tm ->
corestep tr_source geS c m c' m' ->
at_external source (snd c) = Some (ef, sig, args) ->
exists cd' j' d' tm',
corestep tr_target geT d tm d' tm'
/\ trace_match_state cd' j' c' m' d' tm'.