diff options
Diffstat (limited to 'ia32/Conventions1.v')
| -rw-r--r-- | ia32/Conventions1.v | 371 |
1 files changed, 371 insertions, 0 deletions
diff --git a/ia32/Conventions1.v b/ia32/Conventions1.v new file mode 100644 index 0000000..ef9ab6b --- /dev/null +++ b/ia32/Conventions1.v @@ -0,0 +1,371 @@ +(* *********************************************************************) +(* *) +(* The Compcert verified compiler *) +(* *) +(* Xavier Leroy, INRIA Paris-Rocquencourt *) +(* *) +(* Copyright Institut National de Recherche en Informatique et en *) +(* Automatique. All rights reserved. This file is distributed *) +(* under the terms of the INRIA Non-Commercial License Agreement. *) +(* *) +(* *********************************************************************) + +(** Function calling conventions and other conventions regarding the use of + machine registers and stack slots. *) + +Require Import Coqlib. +Require Import AST. +Require Import Events. +Require Import Locations. + +(** * Classification of machine registers *) + +(** Machine registers (type [mreg] in module [Locations]) are divided in + the following groups: +- Callee-save registers, whose value is preserved across a function call. +- Caller-save registers that can be modified during a function call. + + We follow the x86-32 application binary interface (ABI) in our choice + of callee- and caller-save registers. +*) + +Definition int_caller_save_regs := AX :: CX :: DX :: nil. + +Definition float_caller_save_regs := X0 :: X1 :: X2 :: X3 :: X4 :: X5 :: X6 :: X7 :: nil. + +Definition int_callee_save_regs := BX :: SI :: DI :: BP :: nil. + +Definition float_callee_save_regs : list mreg := nil. + +Definition destroyed_at_call := + FP0 :: int_caller_save_regs ++ float_caller_save_regs. + +Definition dummy_int_reg := AX. (**r Used in [Regalloc]. *) +Definition dummy_float_reg := X0. (**r Used in [Regalloc]. *) + +(** The [index_int_callee_save] and [index_float_callee_save] associate + a unique positive integer to callee-save registers. This integer is + used in [Stacking] to determine where to save these registers in + the activation record if they are used by the current function. *) + +Definition index_int_callee_save (r: mreg) := + match r with + | BX => 0 | SI => 1 | DI => 2 | BP => 3 | _ => -1 + end. + +Definition index_float_callee_save (r: mreg) := -1. + +Ltac ElimOrEq := + match goal with + | |- (?x = ?y) \/ _ -> _ => + let H := fresh in + (intro H; elim H; clear H; + [intro H; rewrite <- H; clear H | ElimOrEq]) + | |- False -> _ => + let H := fresh in (intro H; contradiction) + end. + +Ltac OrEq := + match goal with + | |- (?x = ?x) \/ _ => left; reflexivity + | |- (?x = ?y) \/ _ => right; OrEq + | |- False => fail + end. + +Ltac NotOrEq := + match goal with + | |- (?x = ?y) \/ _ -> False => + let H := fresh in ( + intro H; elim H; clear H; [intro; discriminate | NotOrEq]) + | |- False -> False => + contradiction + end. + +Lemma index_int_callee_save_pos: + forall r, In r int_callee_save_regs -> index_int_callee_save r >= 0. +Proof. + intro r. simpl; ElimOrEq; unfold index_int_callee_save; omega. +Qed. + +Lemma index_float_callee_save_pos: + forall r, In r float_callee_save_regs -> index_float_callee_save r >= 0. +Proof. + intro r. simpl; ElimOrEq; unfold index_float_callee_save; omega. +Qed. + +Lemma index_int_callee_save_pos2: + forall r, index_int_callee_save r >= 0 -> In r int_callee_save_regs. +Proof. + destruct r; simpl; intro; omegaContradiction || OrEq. +Qed. + +Lemma index_float_callee_save_pos2: + forall r, index_float_callee_save r >= 0 -> In r float_callee_save_regs. +Proof. + unfold index_float_callee_save; intros. omegaContradiction. +Qed. + +Lemma index_int_callee_save_inj: + forall r1 r2, + In r1 int_callee_save_regs -> + In r2 int_callee_save_regs -> + r1 <> r2 -> + index_int_callee_save r1 <> index_int_callee_save r2. +Proof. + intros r1 r2. + simpl; ElimOrEq; ElimOrEq; unfold index_int_callee_save; + intros; congruence. +Qed. + +Lemma index_float_callee_save_inj: + forall r1 r2, + In r1 float_callee_save_regs -> + In r2 float_callee_save_regs -> + r1 <> r2 -> + index_float_callee_save r1 <> index_float_callee_save r2. +Proof. + simpl; intros. contradiction. +Qed. + +(** The following lemmas show that + (destroyed at call, integer callee-save, float callee-save) + is a partition of the set of machine registers. *) + +Lemma int_float_callee_save_disjoint: + list_disjoint int_callee_save_regs float_callee_save_regs. +Proof. + red; intros r1 r2. simpl; ElimOrEq; ElimOrEq; discriminate. +Qed. + +Lemma register_classification: + forall r, + In r destroyed_at_call \/ In r int_callee_save_regs \/ In r float_callee_save_regs. +Proof. + destruct r; + try (left; simpl; OrEq); + try (right; left; simpl; OrEq); + try (right; right; simpl; OrEq). +Qed. + +Lemma int_callee_save_not_destroyed: + forall r, + In r destroyed_at_call -> In r int_callee_save_regs -> False. +Proof. + intros. revert H0 H. simpl. ElimOrEq; NotOrEq. +Qed. + +Lemma float_callee_save_not_destroyed: + forall r, + In r destroyed_at_call -> In r float_callee_save_regs -> False. +Proof. + intros. revert H0 H. simpl. ElimOrEq; NotOrEq. +Qed. + +Lemma int_callee_save_type: + forall r, In r int_callee_save_regs -> mreg_type r = Tany32. +Proof. + intro. simpl; ElimOrEq; reflexivity. +Qed. + +Lemma float_callee_save_type: + forall r, In r float_callee_save_regs -> mreg_type r = Tany64. +Proof. + intro. simpl; ElimOrEq; reflexivity. +Qed. + +Ltac NoRepet := + match goal with + | |- list_norepet nil => + apply list_norepet_nil + | |- list_norepet (?a :: ?b) => + apply list_norepet_cons; [simpl; intuition discriminate | NoRepet] + end. + +Lemma int_callee_save_norepet: + list_norepet int_callee_save_regs. +Proof. + unfold int_callee_save_regs; NoRepet. +Qed. + +Lemma float_callee_save_norepet: + list_norepet float_callee_save_regs. +Proof. + unfold float_callee_save_regs; NoRepet. +Qed. + +(** * Function calling conventions *) + +(** The functions in this section determine the locations (machine registers + and stack slots) used to communicate arguments and results between the + caller and the callee during function calls. These locations are functions + of the signature of the function and of the call instruction. + Agreement between the caller and the callee on the locations to use + is guaranteed by our dynamic semantics for Cminor and RTL, which demand + that the signature of the call instruction is identical to that of the + called function. + + Calling conventions are largely arbitrary: they must respect the properties + proved in this section (such as no overlapping between the locations + of function arguments), but this leaves much liberty in choosing actual + locations. To ensure binary interoperability of code generated by our + compiler with libraries compiled by another compiler, we + implement the standard x86 conventions. *) + +(** ** Location of function result *) + +(** The result value of a function is passed back to the caller in + registers [AX] or [FP0], depending on the type of the returned value. + We treat a function without result as a function with one integer result. *) + +Definition loc_result (s: signature) : list mreg := + match s.(sig_res) with + | None => AX :: nil + | Some (Tint | Tany32) => AX :: nil + | Some (Tfloat | Tsingle) => FP0 :: nil + | Some Tany64 => X0 :: nil + | Some Tlong => DX :: AX :: nil + end. + +(** The result registers have types compatible with that given in the signature. *) + +Lemma loc_result_type: + forall sig, + subtype_list (proj_sig_res' sig) (map mreg_type (loc_result sig)) = true. +Proof. + intros. unfold proj_sig_res', loc_result. destruct (sig_res sig) as [[]|]; auto. +Qed. + +(** The result locations are caller-save registers *) + +Lemma loc_result_caller_save: + forall (s: signature) (r: mreg), + In r (loc_result s) -> In r destroyed_at_call. +Proof. + intros. + assert (r = AX \/ r = DX \/ r = FP0 \/ r = X0). + unfold loc_result in H. destruct (sig_res s) as [[]|]; simpl in H; intuition. + destruct H0 as [A | [A | [A | A]]]; subst r; simpl; OrEq. +Qed. + +(** ** Location of function arguments *) + +(** All arguments are passed on stack. (Snif.) *) + +Fixpoint loc_arguments_rec + (tyl: list typ) (ofs: Z) {struct tyl} : list loc := + match tyl with + | nil => nil + | Tint :: tys => S Outgoing ofs Tint :: loc_arguments_rec tys (ofs + 1) + | Tfloat :: tys => S Outgoing ofs Tfloat :: loc_arguments_rec tys (ofs + 2) + | Tsingle :: tys => S Outgoing ofs Tsingle :: loc_arguments_rec tys (ofs + 1) + | Tlong :: tys => S Outgoing (ofs + 1) Tint :: S Outgoing ofs Tint :: loc_arguments_rec tys (ofs + 2) + | Tany32 :: tys => S Outgoing ofs Tany32 :: loc_arguments_rec tys (ofs + 1) + | Tany64 :: tys => S Outgoing ofs Tany64 :: loc_arguments_rec tys (ofs + 2) + end. + +(** [loc_arguments s] returns the list of locations where to store arguments + when calling a function with signature [s]. *) + +Definition loc_arguments (s: signature) : list loc := + loc_arguments_rec s.(sig_args) 0. + +(** [size_arguments s] returns the number of [Outgoing] slots used + to call a function with signature [s]. *) + +Fixpoint size_arguments_rec + (tyl: list typ) (ofs: Z) {struct tyl} : Z := + match tyl with + | nil => ofs + | ty :: tys => size_arguments_rec tys (ofs + typesize ty) + end. + +Definition size_arguments (s: signature) : Z := + size_arguments_rec s.(sig_args) 0. + +(** Argument locations are either caller-save registers or [Outgoing] + stack slots at nonnegative offsets. *) + +Definition loc_argument_acceptable (l: loc) : Prop := + match l with + | R r => In r destroyed_at_call + | S Outgoing ofs ty => ofs >= 0 /\ ty <> Tlong + | _ => False + end. + +Remark loc_arguments_rec_charact: + forall tyl ofs l, + In l (loc_arguments_rec tyl ofs) -> + match l with + | S Outgoing ofs' ty => ofs' >= ofs /\ ty <> Tlong + | _ => False + end. +Proof. + induction tyl; simpl loc_arguments_rec; intros. +- destruct H. +- assert (REC: forall ofs1, In l (loc_arguments_rec tyl ofs1) -> ofs1 > ofs -> + match l with + | R _ => False + | S Local _ _ => False + | S Incoming _ _ => False + | S Outgoing ofs' ty => ofs' >= ofs /\ ty <> Tlong + end). + { intros. exploit IHtyl; eauto. destruct l; auto. destruct sl; intuition omega +. } + destruct a; simpl in H; repeat (destruct H); + ((eapply REC; eauto; omega) || (split; [omega|congruence])). +Qed. + +Lemma loc_arguments_acceptable: + forall (s: signature) (l: loc), + In l (loc_arguments s) -> loc_argument_acceptable l. +Proof. + unfold loc_arguments; intros. + exploit loc_arguments_rec_charact; eauto. + unfold loc_argument_acceptable. + destruct l; tauto. +Qed. + +Hint Resolve loc_arguments_acceptable: locs. + +(** The offsets of [Outgoing] arguments are below [size_arguments s]. *) + +Remark size_arguments_rec_above: + forall tyl ofs0, ofs0 <= size_arguments_rec tyl ofs0. +Proof. + induction tyl; simpl; intros. + omega. + apply Zle_trans with (ofs0 + typesize a); auto. + generalize (typesize_pos a); omega. +Qed. + +Lemma size_arguments_above: + forall s, size_arguments s >= 0. +Proof. + intros; unfold size_arguments. apply Zle_ge. + apply size_arguments_rec_above. +Qed. + +Lemma loc_arguments_bounded: + forall (s: signature) (ofs: Z) (ty: typ), + In (S Outgoing ofs ty) (loc_arguments s) -> + ofs + typesize ty <= size_arguments s. +Proof. + intros until ty. unfold loc_arguments, size_arguments. generalize (sig_args s) 0. + induction l; simpl; intros. +- contradiction. +- Ltac decomp := + match goal with + | [ H: _ \/ _ |- _ ] => destruct H; decomp + | [ H: S _ _ _ = S _ _ _ |- _ ] => inv H + | _ => idtac + end. + destruct a; simpl in H; decomp; auto; try apply size_arguments_rec_above. + simpl typesize. replace (z + 1 + 1) with (z + 2) by omega. apply size_arguments_rec_above. + simpl typesize. apply Zle_trans with (ofs + 2). omega. apply size_arguments_rec_above. +Qed. + +Lemma loc_arguments_main: + loc_arguments signature_main = nil. +Proof. + reflexivity. +Qed. |