Section SOUNDNESS.
Variable ge: genv.
Variable sp: block.
Variables m m': mem.
Hypothesis PERM: forall b ofs k p, Mem.perm m b ofs k p -> Mem.perm m' b ofs k p.

Lemma needs_of_operation_sound:
forall op args v nv args',
eval_operation ge (Vptr sp Ptrofs.zero) op args m = Some v ->
vagree_list args args' (needs_of_operation op nv) ->
nv <> Nothing ->
exists v',
eval_operation ge (Vptr sp Ptrofs.zero) op args' m' = Some v'
/\ vagree v v' nv.