Definition do_ef_volatile_load (chunk: memory_chunk)
       (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
  match vargs with
  | Vptr b ofs :: nil => do w',t,v <- do_volatile_load w chunk m b ofs; Some(w',t,v,m)
  | _ => None
  end.Definition do_ef_volatile_store (chunk: memory_chunk)
       (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
  match vargs with
  | Vptr b ofs :: v :: nil => do w',t,m' <- do_volatile_store w chunk m b ofs v; Some(w',t,Vundef,m')
  | _ => None
  end.Definition do_ef_volatile_load_global (chunk: memory_chunk) (id: ident) (ofs: ptrofs)
       (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
  do b <- Genv.find_symbol ge id; do_ef_volatile_load chunk w (Vptr b ofs :: vargs) m.Definition do_ef_volatile_store_global (chunk: memory_chunk) (id: ident) (ofs: ptrofs)
       (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
  do b <- Genv.find_symbol ge id; do_ef_volatile_store chunk w (Vptr b ofs :: vargs) m.Definition do_alloc_size (v: val) : option ptrofs :=
  match v with
  | Vint n => if Archi.ptr64 then None else Some (Ptrofs.of_int n)
  | Vlong n => if Archi.ptr64 then Some (Ptrofs.of_int64 n) else None
  | _ => None
  end.Definition do_ef_malloc
       (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
  match vargs with
  | v :: nil =>
      do sz <- do_alloc_size v;
      let (m', b) := Mem.alloc m (- size_chunk Mptr) (Ptrofs.unsigned sz) in
      do m'' <- Mem.store Mptr m' b (- size_chunk Mptr) v;
      Some(w, E0, Vptr b Ptrofs.zero, m'')
  | _ => None
  end.Definition do_ef_free
       (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
  match vargs with
  | Vptr b lo :: nil =>
      do vsz <- Mem.load Mptr m b (Ptrofs.unsigned lo - size_chunk Mptr);
      do sz <- do_alloc_size vsz;
      check (zlt 0 (Ptrofs.unsigned sz));
      do m' <- Mem.free m b (Ptrofs.unsigned lo - size_chunk Mptr) (Ptrofs.unsigned lo + Ptrofs.unsigned sz);
      Some(w, E0, Vundef, m')
  | _ => None
  end.Definition do_ef_memcpy (sz al: Z)
       (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
  match vargs with
  | Vptr bdst odst :: Vptr bsrc osrc :: nil =>
      if decide (memcpy_args_ok sz al bdst (Ptrofs.unsigned odst) bsrc (Ptrofs.unsigned osrc)) then
        do bytes <- Mem.loadbytes m bsrc (Ptrofs.unsigned osrc) sz;
        do m' <- Mem.storebytes m bdst (Ptrofs.unsigned odst) bytes;
        Some(w, E0, Vundef, m')
      else None
  | _ => None
  end.Definition do_ef_annot (text: string) (targs: list typ)
       (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
  do args <- list_eventval_of_val vargs targs;
  Some(w, Event_annot text args :: E0, Vundef, m).Definition do_ef_annot_val (text: string) (targ: typ)
       (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
  match vargs with
  | varg :: nil =>
      do arg <- eventval_of_val varg targ;
      Some(w, Event_annot text (arg :: nil) :: E0, varg, m)
  | _ => None
  end.Definition do_ef_debug (kind: positive) (text: ident) (targs: list typ)
       (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
  Some(w, E0, Vundef, m).Definition do_external (ef: external_function):
       world -> list val -> mem -> option (world * trace * val * mem) :=
  match ef with
  | EF_external name sg => do_external_function name sg ge
  | EF_builtin name sg => do_external_function name sg ge
  | EF_runtime name sg => do_external_function name sg ge
  | EF_vload chunk => do_ef_volatile_load chunk
  | EF_vstore chunk => do_ef_volatile_store chunk
  | EF_malloc => do_ef_malloc
  | EF_free => do_ef_free
  | EF_memcpy sz al => do_ef_memcpy sz al
  | EF_annot kind text targs => do_ef_annot text targs
  | EF_annot_val kind text targ => do_ef_annot_val text targ
  | EF_inline_asm text sg clob => do_inline_assembly text sg ge
  | EF_debug kind text targs => do_ef_debug kind text targs
  end.

Lemma do_ef_external_sound: forall ef w vargs m w' t vres m', do_external ef w vargs m = Some(w', t, vres, m') -> external_call ef ge vargs m t vres m' /\ possible_trace w t w'.