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. --- aarch64/Conventions1.v | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) (limited to 'aarch64/Conventions1.v') diff --git a/aarch64/Conventions1.v b/aarch64/Conventions1.v index 5914e8f2..575d058d 100644 --- a/aarch64/Conventions1.v +++ b/aarch64/Conventions1.v @@ -102,10 +102,9 @@ Definition is_float_reg (r: mreg): bool := with one integer result. *) Definition loc_result (s: signature) : rpair mreg := - match s.(sig_res) with - | None => One R0 - | Some (Tint | Tlong | Tany32 | Tany64) => One R0 - | Some (Tfloat | Tsingle) => One F0 + match proj_sig_res s with + | Tint | Tlong | Tany32 | Tany64 => One R0 + | Tfloat | Tsingle => One F0 end. (** The result registers have types compatible with that given in the signature. *) @@ -114,7 +113,7 @@ 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. destruct (sig_res sig) as [[]|]; auto. + intros. unfold loc_result. destruct (proj_sig_res sig); auto. Qed. (** The result locations are caller-save registers *) @@ -124,7 +123,7 @@ Lemma loc_result_caller_save: forall_rpair (fun r => is_callee_save r = false) (loc_result s). Proof. intros. - unfold loc_result. destruct (sig_res s) as [[]|]; simpl; auto. + unfold loc_result. 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. *) @@ -134,12 +133,12 @@ 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; destruct (sig_res sg) as [[]|]; exact I. + intros; unfold loc_result; destruct (proj_sig_res sg); exact I. Qed. (** The location of the result depends only on the result part of the signature *) @@ -147,7 +146,7 @@ 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. rewrite H; auto. + intros. unfold loc_result, proj_sig_res. rewrite H; auto. Qed. (** ** Location of function arguments *) -- cgit