Section TRANSL_LABEL.
Remark iterate_op_label:
forall op1 op2 l k,
(forall so, nolabel (op1 so)) ->
(forall so, nolabel (op2 so)) ->
tail_nolabel k (iterate_op op1 op2 l k).
Hint Resolve iterate_op_label: labels.
Remark loadimm_label:
forall r n k, tail_nolabel k (loadimm r n k).
Hint Resolve loadimm_label: labels.
Remark addimm_label:
forall r1 r2 n k, tail_nolabel k (addimm r1 r2 n k).
Hint Resolve addimm_label: labels.
Remark andimm_label:
forall r1 r2 n k, tail_nolabel k (andimm r1 r2 n k).
Hint Resolve andimm_label: labels.
Remark rsubimm_label:
forall r1 r2 n k, tail_nolabel k (rsubimm r1 r2 n k).
Hint Resolve rsubimm_label: labels.
Remark orimm_label:
forall r1 r2 n k, tail_nolabel k (orimm r1 r2 n k).
Hint Resolve orimm_label: labels.
Remark xorimm_label:
forall r1 r2 n k, tail_nolabel k (xorimm r1 r2 n k).
Hint Resolve xorimm_label: labels.
Remark indexed_memory_access_label:
forall mk_instr mk_immed base ofs k,
(forall r n, nolabel (mk_instr r n)) ->
tail_nolabel k (indexed_memory_access mk_instr mk_immed base ofs k).
Hint Resolve indexed_memory_access_label.
Remark loadind_label:
forall base ofs ty dst k c, loadind base ofs ty dst k = OK c -> tail_nolabel k c.
Remark storeind_label:
forall base ofs ty src k c, storeind src base ofs ty k = OK c -> tail_nolabel k c.
Remark save_lr_label:
forall ofs k, tail_nolabel k (save_lr ofs k).
Remark transl_cond_label:
forall cond args k c, transl_cond cond args k = OK c -> tail_nolabel k c.
Remark transl_op_label:
forall op args r k c, transl_op op args r k = OK c -> tail_nolabel k c.
Remark transl_memory_access_label:
forall (mk_instr_imm: ireg -> int -> instruction)
(mk_instr_gen: option (ireg -> shift_op -> instruction))
(mk_immed: int -> int)
(addr: addressing) (args: list mreg) c k,
transl_memory_access mk_instr_imm mk_instr_gen mk_immed addr args k = OK c ->
(forall r n, nolabel (mk_instr_imm r n)) ->
(match mk_instr_gen with
| None => True
| Some f => forall r sa, nolabel (f r sa)
end) ->
tail_nolabel k c.
End TRANSL_LABEL.
(** A valid branch in a piece of Mach code translates to a valid ``go to'' transition in the generated PPC code. *)
(** Existence of return addresses *)
(** * Proof of semantic preservation *)
(** Semantic preservation is proved using simulation diagrams of the following form. << st1 --------------- st2 |                   | t|                  *|t |                   | v                   v st1'--------------- st2' >> The invariant is the [match_states] predicate below, which includes: - The ARM code pointed by the PC register is the translation of the current Mach code sequence. - Mach register values and ARM register values agree. *)
Inductive match_states: Mach.state -> Asm.state -> Prop :=
| match_states_intro:
forall s fb sp c ep ms m m' rs f tf tc
(STACKS: match_stack ge s)
(FIND: Genv.find_funct_ptr ge fb = Some (Internal f))
(MEXT: Mem.extends m m')
(AT: transl_code_at_pc ge (rs PC) fb f c ep tf tc)
(AG: agree ms sp rs)
(DXP: ep = true -> rs#IR12 = parent_sp s),
match_states (Mach.State s fb sp c ms m)
(Asm.State rs m')
| match_states_call:
forall s fb ms m m' rs
(STACKS: match_stack ge s)
(MEXT: Mem.extends m m')
(AG: agree ms (parent_sp s) rs)
(ATPC: rs PC = Vptr fb Ptrofs.zero)
(ATLR: rs RA = parent_ra s),
match_states (Mach.Callstate s fb ms m)
(Asm.State rs m')
| match_states_return:
forall s ms m m' rs
(STACKS: match_stack ge s)
(MEXT: Mem.extends m m')
(AG: agree ms (parent_sp s) rs)
(ATPC: rs PC = parent_ra s),
match_states (Mach.Returnstate s ms m)
(Asm.State rs m').

Lemma exec_straight_steps_goto:
forall s fb f rs1 i c ep tf tc m1' m2 m2' sp ms2 lbl c',
match_stack ge s ->
Mem.extends m2 m2' ->
Genv.find_funct_ptr ge fb = Some (Internal f) ->
Mach.find_label lbl f.(Mach.fn_code) = Some c' ->
transl_code_at_pc ge (rs1 PC) fb f (i :: c) ep tf tc ->
it1_is_parent ep i = false ->
(forall k c (TR: transl_instr f i ep k = OK c),
exists jmp, exists k', exists rs2,
exec_straight tge tf c rs1 m1' (jmp :: k') rs2 m2'
/\ agree ms2 sp rs2
/\ exec_instr tge tf jmp rs2 m2' = goto_label tf lbl rs2 m2') ->
exists st',
plus step tge (State rs1 m1') E0 st' /\
match_states (Mach.State s fb sp c' ms2 m2) st'.