From be0b1872bf2ad36df9b0c7a0ffa63b9e77fa769b Mon Sep 17 00:00:00 2001 From: Xavier Leroy Date: Tue, 18 Feb 2020 16:57:17 +0100 Subject: Refine the type of function results in AST.signature Before it was "option typ". Now it is a proper inductive type that can also express small integer types (8/16-bit unsigned/signed integers). One benefit is that external functions get more precise types that control better their return values. As a consequence, the CompCert C type preservation property now holds unconditionally, without extra typing hypotheses on external functions. --- powerpc/Conventions1.v | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-) (limited to 'powerpc/Conventions1.v') diff --git a/powerpc/Conventions1.v b/powerpc/Conventions1.v index 1de55c1a..7c1b2750 100644 --- a/powerpc/Conventions1.v +++ b/powerpc/Conventions1.v @@ -117,18 +117,16 @@ Definition dummy_float_reg := F0. (**r Used in [Coloring]. *) We treat a function without result as a function with one integer result. *) Definition loc_result_32 (s: signature) : rpair mreg := - match s.(sig_res) with - | None => One R3 - | Some (Tint | Tany32) => One R3 - | Some (Tfloat | Tsingle | Tany64) => One F1 - | Some Tlong => Twolong R3 R4 + match proj_sig_res s with + | Tint | Tany32 => One R3 + | Tfloat | Tsingle | Tany64 => One F1 + | Tlong => Twolong R3 R4 end. Definition loc_result_64 (s: signature) : rpair mreg := - match s.(sig_res) with - | None => One R3 - | Some (Tint | Tlong | Tany32 | Tany64) => One R3 - | Some (Tfloat | Tsingle) => One F1 + match proj_sig_res s with + | Tint | Tlong | Tany32 | Tany64 => One R3 + | Tfloat | Tsingle => One F1 end. Definition loc_result := @@ -140,8 +138,8 @@ Lemma loc_result_type: forall sig, subtype (proj_sig_res sig) (typ_rpair mreg_type (loc_result sig)) = true. Proof. - intros. unfold proj_sig_res, loc_result, loc_result_32, loc_result_64, mreg_type. - destruct Archi.ptr64 eqn:?; destruct (sig_res sig) as [[]|]; destruct Archi.ppc64; simpl; auto. + intros. unfold loc_result, loc_result_32, loc_result_64, mreg_type. + destruct Archi.ptr64 eqn:?; destruct (proj_sig_res sig); destruct Archi.ppc64; simpl; auto. Qed. (** The result locations are caller-save registers *) @@ -151,7 +149,7 @@ Lemma loc_result_caller_save: forall_rpair (fun r => is_callee_save r = false) (loc_result s). Proof. intros. unfold loc_result, loc_result_32, loc_result_64, is_callee_save; - destruct Archi.ptr64; destruct (sig_res s) as [[]|]; simpl; auto. + destruct Archi.ptr64; destruct (proj_sig_res s); simpl; auto. Qed. (** If the result is in a pair of registers, those registers are distinct and have type [Tint] at least. *) @@ -161,13 +159,13 @@ Lemma loc_result_pair: match loc_result sg with | One _ => True | Twolong r1 r2 => - r1 <> r2 /\ sg.(sig_res) = Some Tlong + r1 <> r2 /\ proj_sig_res sg = Tlong /\ subtype Tint (mreg_type r1) = true /\ subtype Tint (mreg_type r2) = true /\ Archi.ptr64 = false end. Proof. intros; unfold loc_result, loc_result_32, loc_result_64, mreg_type; - destruct Archi.ptr64; destruct (sig_res sg) as [[]|]; destruct Archi.ppc64; simpl; auto. + destruct Archi.ptr64; destruct (proj_sig_res sg); destruct Archi.ppc64; simpl; auto. split; auto. congruence. split; auto. congruence. Qed. @@ -177,7 +175,7 @@ Qed. Lemma loc_result_exten: forall s1 s2, s1.(sig_res) = s2.(sig_res) -> loc_result s1 = loc_result s2. Proof. - intros. unfold loc_result, loc_result_32, loc_result_64. + intros. unfold loc_result, loc_result_32, loc_result_64, proj_sig_res. destruct Archi.ptr64; rewrite H; auto. Qed. -- cgit