diff options
Diffstat (limited to 'riscV/Conventions1.v')
| -rw-r--r-- | riscV/Conventions1.v | 350 |
1 files changed, 153 insertions, 197 deletions
diff --git a/riscV/Conventions1.v b/riscV/Conventions1.v index df7ddfd2..17326139 100644 --- a/riscV/Conventions1.v +++ b/riscV/Conventions1.v @@ -105,7 +105,9 @@ Definition is_float_reg (r: mreg) := 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 RISC-V conventions. *) + implement the standard RISC-V conventions as found here: + https://github.com/riscv/riscv-elf-psabi-doc/blob/master/riscv-elf.md +*) (** ** Location of function result *) @@ -115,11 +117,10 @@ Definition is_float_reg (r: mreg) := with one integer result. *) Definition loc_result (s: signature) : rpair mreg := - match s.(sig_res) with - | None => One R10 - | Some (Tint | Tany32) => One R10 - | Some (Tfloat | Tsingle | Tany64) => One F10 - | Some Tlong => if Archi.ptr64 then One R10 else Twolong R11 R10 + match proj_sig_res s with + | Tint | Tany32 => One R10 + | Tfloat | Tsingle | Tany64 => One F10 + | Tlong => if Archi.ptr64 then One R10 else Twolong R11 R10 end. (** The result registers have types compatible with that given in the signature. *) @@ -128,8 +129,8 @@ 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, mreg_type; - destruct (sig_res sig) as [[]|]; auto; destruct Archi.ptr64; auto. + intros. unfold loc_result, mreg_type; + destruct (proj_sig_res sig); auto; destruct Archi.ptr64; auto. Qed. (** The result locations are caller-save registers *) @@ -139,7 +140,7 @@ Lemma loc_result_caller_save: forall_rpair (fun r => is_callee_save r = false) (loc_result s). Proof. intros. unfold loc_result, is_callee_save; - destruct (sig_res s) as [[]|]; simpl; auto; destruct Archi.ptr64; simpl; auto. + destruct (proj_sig_res s); simpl; auto; destruct Archi.ptr64; simpl; auto. Qed. (** If the result is in a pair of registers, those registers are distinct and have type [Tint] at least. *) @@ -149,13 +150,13 @@ 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; destruct (sig_res sg) as [[]|]; auto. + unfold loc_result; destruct (proj_sig_res sg); auto. unfold mreg_type; destruct Archi.ptr64; auto. split; auto. congruence. Qed. @@ -165,43 +166,37 @@ 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 *) -(** The RISC-V ABI states the following convention for passing arguments +(** The RISC-V ABI states the following conventions for passing arguments to a function: -- Arguments are passed in registers when possible. - -- Up to eight integer registers (ai: int_param_regs) and up to eight - floating-point registers (fai: float_param_regs) are used for this - purpose. - -- If the arguments to a function are conceptualized as fields of a C - struct, each with pointer alignment, the argument registers are a - shadow of the first eight pointer-words of that struct. If argument - i < 8 is a floating-point type, it is passed in floating-point - register fa_i; otherwise, it is passed in integer register a_i. - -- When primitive arguments twice the size of a pointer-word are passed - on the stack, they are naturally aligned. When they are passed in the - integer registers, they reside in an aligned even-odd register pair, - with the even register holding the least-significant bits. - -- Floating-point arguments to variadic functions (except those that - are explicitly named in the parameter list) are passed in integer - registers. - -- The portion of the conceptual struct that is not passed in argument - registers is passed on the stack. The stack pointer sp points to the - first argument not passed in a register. - -The bit about variadic functions doesn't quite fit CompCert's model. -We do our best by passing the FP arguments in registers, as usual, -and reserving the corresponding integer registers, so that fixup -code can be introduced in the Asmexpand pass. +- RV64, not variadic: pass the first 8 integer arguments in + integer registers (a1...a8: int_param_regs), the first 8 FP arguments + in FP registers (fa1...fa8: float_param_regs), and the remaining + arguments on the stack, in 8-byte slots. + +- RV32, not variadic: same, but arguments of 64-bit integer type + are passed in two consecutive integer registers (a(i), a(i+1)) + or in a(8) and on a 32-bit word on the stack. Stack-allocated + arguments are aligned to their natural alignment. + +- RV64, variadic: pass the first 8 arguments in integer registers + (a1...a8), including FP arguments; pass the remaining arguments on + the stack, in 8-byte slots. + +- RV32, variadic: same, but arguments of 64-bit types (integers as well + as floats) are passed in two consecutive aligned integer registers + (a(2i), a(2i+1)). + +The passing of FP arguments to variadic functions in integer registers +doesn't quite fit CompCert's model. We do our best by passing the FP +arguments in registers, as usual, and reserving the corresponding +integer registers, so that fixup code can be introduced in the +Asmexpand pass. *) Definition int_param_regs := @@ -209,80 +204,84 @@ Definition int_param_regs := Definition float_param_regs := F10 :: F11 :: F12 :: F13 :: F14 :: F15 :: F16 :: F17 :: nil. -Definition one_arg (regs: list mreg) (rn: Z) (ofs: Z) (ty: typ) - (rec: Z -> Z -> list (rpair loc)) := - match list_nth_z regs rn with +Definition int_arg (ri rf ofs: Z) (ty: typ) + (rec: Z -> Z -> Z -> list (rpair loc)) := + match list_nth_z int_param_regs ri with | Some r => - One(R r) :: rec (rn + 1) ofs + One(R r) :: rec (ri + 1) rf ofs | None => - let ofs := align ofs (typealign ty) in - One(S Outgoing ofs ty) :: rec rn (ofs + (if Archi.ptr64 then 2 else typesize ty)) + let ofs := align ofs (typesize ty) in + One(S Outgoing ofs ty) + :: rec ri rf (ofs + (if Archi.ptr64 then 2 else typesize ty)) end. -Definition two_args (regs: list mreg) (rn: Z) (ofs: Z) - (rec: Z -> Z -> list (rpair loc)) := - let rn := align rn 2 in - match list_nth_z regs rn, list_nth_z regs (rn + 1) with - | Some r1, Some r2 => - Twolong (R r2) (R r1) :: rec (rn + 2) ofs - | _, _ => - let ofs := align ofs 2 in - Twolong (S Outgoing (ofs + 1) Tint) (S Outgoing ofs Tint) :: - rec rn (ofs + 2) +Definition float_arg (va: bool) (ri rf ofs: Z) (ty: typ) + (rec: Z -> Z -> Z -> list (rpair loc)) := + match list_nth_z float_param_regs rf with + | Some r => + if va then + (let ri' := (* reserve 1 or 2 aligned integer registers *) + if Archi.ptr64 || zeq (typesize ty) 1 then ri + 1 else align ri 2 + 2 in + if zle ri' 8 then + (* we have enough integer registers, put argument in FP reg + and fixup code will put it in one or two integer regs *) + One (R r) :: rec ri' (rf + 1) ofs + else + (* we are out of integer registers, pass argument on stack *) + let ofs := align ofs (typesize ty) in + One(S Outgoing ofs ty) + :: rec ri' rf (ofs + (if Archi.ptr64 then 2 else typesize ty))) + else + One (R r) :: rec ri (rf + 1) ofs + | None => + let ofs := align ofs (typesize ty) in + One(S Outgoing ofs ty) + :: rec ri rf (ofs + (if Archi.ptr64 then 2 else typesize ty)) end. -Definition hybrid_arg (regs: list mreg) (rn: Z) (ofs: Z) (ty: typ) - (rec: Z -> Z -> list (rpair loc)) := - let rn := align rn 2 in - match list_nth_z regs rn with - | Some r => - One (R r) :: rec (rn + 2) ofs - | None => +Definition split_long_arg (va: bool) (ri rf ofs: Z) + (rec: Z -> Z -> Z -> list (rpair loc)) := + let ri := if va then align ri 2 else ri in + match list_nth_z int_param_regs ri, list_nth_z int_param_regs (ri + 1) with + | Some r1, Some r2 => + Twolong (R r2) (R r1) :: rec (ri + 2) rf ofs + | Some r1, None => + Twolong (S Outgoing ofs Tint) (R r1) :: rec (ri + 1) rf (ofs + 1) + | None, _ => let ofs := align ofs 2 in - One (S Outgoing ofs ty) :: rec rn (ofs + 2) + Twolong (S Outgoing (ofs + 1) Tint) (S Outgoing ofs Tint) :: + rec ri rf (ofs + 2) end. Fixpoint loc_arguments_rec (va: bool) - (tyl: list typ) (r ofs: Z) {struct tyl} : list (rpair loc) := + (tyl: list typ) (ri rf ofs: Z) {struct tyl} : list (rpair loc) := match tyl with | nil => nil | (Tint | Tany32) as ty :: tys => - one_arg int_param_regs r ofs ty (loc_arguments_rec va tys) + (* pass in one integer register or on stack *) + int_arg ri rf ofs ty (loc_arguments_rec va tys) | Tsingle as ty :: tys => - one_arg float_param_regs r ofs ty (loc_arguments_rec va tys) + (* pass in one FP register or on stack. + If vararg, reserve 1 integer register. *) + float_arg va ri rf ofs ty (loc_arguments_rec va tys) | Tlong as ty :: tys => - if Archi.ptr64 - then one_arg int_param_regs r ofs ty (loc_arguments_rec va tys) - else two_args int_param_regs r ofs (loc_arguments_rec va tys) + if Archi.ptr64 then + (* pass in one integer register or on stack *) + int_arg ri rf ofs ty (loc_arguments_rec va tys) + else + (* pass in register pair or on stack; align register pair if vararg *) + split_long_arg va ri rf ofs(loc_arguments_rec va tys) | (Tfloat | Tany64) as ty :: tys => - if va && negb Archi.ptr64 - then hybrid_arg float_param_regs r ofs ty (loc_arguments_rec va tys) - else one_arg float_param_regs r ofs ty (loc_arguments_rec va tys) + (* pass in one FP register or on stack. + If vararg, reserve 1 or 2 integer registers. *) + float_arg va ri rf ofs ty (loc_arguments_rec va tys) 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 (rpair loc) := - loc_arguments_rec s.(sig_cc).(cc_vararg) s.(sig_args) 0 0. - -(** [size_arguments s] returns the number of [Outgoing] slots used - to call a function with signature [s]. *) - -Definition max_outgoing_1 (accu: Z) (l: loc) : Z := - match l with - | S Outgoing ofs ty => Z.max accu (ofs + typesize ty) - | _ => accu - end. - -Definition max_outgoing_2 (accu: Z) (rl: rpair loc) : Z := - match rl with - | One l => max_outgoing_1 accu l - | Twolong l1 l2 => max_outgoing_1 (max_outgoing_1 accu l1) l2 - end. - -Definition size_arguments (s: signature) : Z := - List.fold_left max_outgoing_2 (loc_arguments s) 0. + loc_arguments_rec s.(sig_cc).(cc_vararg) s.(sig_args) 0 0 0. (** Argument locations are either non-temporary registers or [Outgoing] stack slots at nonnegative offsets. *) @@ -295,90 +294,87 @@ Definition loc_argument_acceptable (l: loc) : Prop := end. Lemma loc_arguments_rec_charact: - forall va tyl rn ofs p, + forall va tyl ri rf ofs p, ofs >= 0 -> - In p (loc_arguments_rec va tyl rn ofs) -> forall_rpair loc_argument_acceptable p. + In p (loc_arguments_rec va tyl ri rf ofs) -> forall_rpair loc_argument_acceptable p. Proof. set (OK := fun (l: list (rpair loc)) => forall p, In p l -> forall_rpair loc_argument_acceptable p). - set (OKF := fun (f: Z -> Z -> list (rpair loc)) => - forall rn ofs, ofs >= 0 -> OK (f rn ofs)). - set (OKREGS := fun (l: list mreg) => forall r, In r l -> is_callee_save r = false). - assert (AL: forall ofs ty, ofs >= 0 -> align ofs (typealign ty) >= 0). + set (OKF := fun (f: Z -> Z -> Z -> list (rpair loc)) => + forall ri rf ofs, ofs >= 0 -> OK (f ri rf ofs)). + assert (CSI: forall r, In r int_param_regs -> is_callee_save r = false). + { decide_goal. } + assert (CSF: forall r, In r float_param_regs -> is_callee_save r = false). + { decide_goal. } + assert (AL: forall ofs ty, ofs >= 0 -> align ofs (typesize ty) >= 0). { intros. - assert (ofs <= align ofs (typealign ty)) by (apply align_le; apply typealign_pos). + assert (ofs <= align ofs (typesize ty)) by (apply align_le; apply typesize_pos). omega. } + assert (ALD: forall ofs ty, ofs >= 0 -> (typealign ty | align ofs (typesize ty))). + { intros. eapply Z.divide_trans. apply typealign_typesize. + apply align_divides. apply typesize_pos. } assert (SK: (if Archi.ptr64 then 2 else 1) > 0). { destruct Archi.ptr64; omega. } assert (SKK: forall ty, (if Archi.ptr64 then 2 else typesize ty) > 0). { intros. destruct Archi.ptr64. omega. apply typesize_pos. } - assert (A: forall regs rn ofs ty f, - OKREGS regs -> OKF f -> ofs >= 0 -> OK (one_arg regs rn ofs ty f)). - { intros until f; intros OR OF OO; red; unfold one_arg; intros. - destruct (list_nth_z regs rn) as [r|] eqn:NTH; destruct H. - - subst p; simpl. apply OR. eapply list_nth_z_in; eauto. + assert (A: forall ri rf ofs ty f, + OKF f -> ofs >= 0 -> OK (int_arg ri rf ofs ty f)). + { intros until f; intros OF OO; red; unfold int_arg; intros. + destruct (list_nth_z int_param_regs ri) as [r|] eqn:NTH; destruct H. + - subst p; simpl. apply CSI. eapply list_nth_z_in; eauto. - eapply OF; eauto. - subst p; simpl. auto using align_divides, typealign_pos. - eapply OF; [idtac|eauto]. generalize (AL ofs ty OO) (SKK ty); omega. } - assert (B: forall regs rn ofs f, - OKREGS regs -> OKF f -> ofs >= 0 -> OK (two_args regs rn ofs f)). - { intros until f; intros OR OF OO; unfold two_args. - set (rn' := align rn 2). + assert (B: forall va ri rf ofs ty f, + OKF f -> ofs >= 0 -> OK (float_arg va ri rf ofs ty f)). + { intros until f; intros OF OO; red; unfold float_arg; intros. + destruct (list_nth_z float_param_regs rf) as [r|] eqn:NTH. + - set (ri' := if Archi.ptr64 || zeq (typesize ty) 1 then ri + 1 else align ri 2 + 2) in *. + destruct va; [destruct (zle ri' 8)|idtac]; destruct H. + + subst p; simpl. apply CSF. eapply list_nth_z_in; eauto. + + eapply OF; eauto. + + subst p; repeat split; auto. + + eapply OF; [idtac|eauto]. generalize (AL ofs ty OO) (SKK ty); omega. + + subst p; simpl. apply CSF. eapply list_nth_z_in; eauto. + + eapply OF; eauto. + - destruct H. + + subst p; repeat split; auto. + + eapply OF; [idtac|eauto]. generalize (AL ofs ty OO) (SKK ty); omega. + } + assert (C: forall va ri rf ofs f, + OKF f -> ofs >= 0 -> OK (split_long_arg va ri rf ofs f)). + { intros until f; intros OF OO; unfold split_long_arg. + set (ri' := if va then align ri 2 else ri). set (ofs' := align ofs 2). assert (OO': ofs' >= 0) by (apply (AL ofs Tlong); auto). - assert (DFL: OK (Twolong (S Outgoing (ofs' + 1) Tint) (S Outgoing ofs' Tint) - :: f rn' (ofs' + 2))). - { red; simpl; intros. destruct H. - - subst p; simpl. - repeat split; auto using Z.divide_1_l. omega. - - eapply OF; [idtac|eauto]. omega. - } - destruct (list_nth_z regs rn') as [r1|] eqn:NTH1; - destruct (list_nth_z regs (rn' + 1)) as [r2|] eqn:NTH2; - try apply DFL. - red; simpl; intros; destruct H. - - subst p; simpl. split; apply OR; eauto using list_nth_z_in. - - eapply OF; [idtac|eauto]. auto. + destruct (list_nth_z int_param_regs ri') as [r1|] eqn:NTH1; + [destruct (list_nth_z int_param_regs (ri'+1)) as [r2|] eqn:NTH2 | idtac]. + - red; simpl; intros; destruct H. + + subst p; split; apply CSI; eauto using list_nth_z_in. + + eapply OF; [idtac|eauto]. omega. + - red; simpl; intros; destruct H. + + subst p; split. split; auto using Z.divide_1_l. apply CSI; eauto using list_nth_z_in. + + eapply OF; [idtac|eauto]. omega. + - red; simpl; intros; destruct H. + + subst p; repeat split; auto using Z.divide_1_l. omega. + + eapply OF; [idtac|eauto]. omega. } - assert (C: forall regs rn ofs ty f, - OKREGS regs -> OKF f -> ofs >= 0 -> typealign ty = 1 -> OK (hybrid_arg regs rn ofs ty f)). - { intros until f; intros OR OF OO OTY; unfold hybrid_arg; red; intros. - set (rn' := align rn 2) in *. - destruct (list_nth_z regs rn') as [r|] eqn:NTH; destruct H. - - subst p; simpl. apply OR. eapply list_nth_z_in; eauto. - - eapply OF; eauto. - - subst p; simpl. rewrite OTY. split. apply (AL ofs Tlong OO). apply Z.divide_1_l. - - eapply OF; [idtac|eauto]. generalize (AL ofs Tlong OO); simpl; omega. - } - assert (D: OKREGS int_param_regs). - { red. decide_goal. } - assert (E: OKREGS float_param_regs). - { red. decide_goal. } - - cut (forall va tyl rn ofs, ofs >= 0 -> OK (loc_arguments_rec va tyl rn ofs)). + cut (forall va tyl ri rf ofs, ofs >= 0 -> OK (loc_arguments_rec va tyl ri rf ofs)). unfold OK. eauto. induction tyl as [ | ty1 tyl]; intros until ofs; intros OO; simpl. - red; simpl; tauto. - destruct ty1. + (* int *) apply A; auto. -+ (* float *) - destruct (va && negb Archi.ptr64). - apply C; auto. - apply A; auto. ++ (* float *) apply B; auto. + (* long *) destruct Archi.ptr64. apply A; auto. - apply B; auto. -+ (* single *) - apply A; auto. -+ (* any32 *) - apply A; auto. -+ (* any64 *) - destruct (va && negb Archi.ptr64). apply C; auto. - apply A; auto. ++ (* single *) apply B; auto. ++ (* any32 *) apply A; auto. ++ (* any64 *) apply B; auto. Qed. Lemma loc_arguments_acceptable: @@ -388,54 +384,14 @@ Proof. unfold loc_arguments; intros. eapply loc_arguments_rec_charact; eauto. omega. Qed. -(** The offsets of [Outgoing] arguments are below [size_arguments s]. *) - -Remark fold_max_outgoing_above: - forall l n, fold_left max_outgoing_2 l n >= n. -Proof. - assert (A: forall n l, max_outgoing_1 n l >= n). - { intros; unfold max_outgoing_1. destruct l as [_ | []]; xomega. } - induction l; simpl; intros. - - omega. - - eapply Zge_trans. eauto. - destruct a; simpl. apply A. eapply Zge_trans; eauto. -Qed. - -Lemma size_arguments_above: - forall s, size_arguments s >= 0. -Proof. - intros. apply fold_max_outgoing_above. -Qed. - -Lemma loc_arguments_bounded: - forall (s: signature) (ofs: Z) (ty: typ), - In (S Outgoing ofs ty) (regs_of_rpairs (loc_arguments s)) -> - ofs + typesize ty <= size_arguments s. -Proof. - intros until ty. - assert (A: forall n l, n <= max_outgoing_1 n l). - { intros; unfold max_outgoing_1. destruct l as [_ | []]; xomega. } - assert (B: forall p n, - In (S Outgoing ofs ty) (regs_of_rpair p) -> - ofs + typesize ty <= max_outgoing_2 n p). - { intros. destruct p; simpl in H; intuition; subst; simpl. - - xomega. - - eapply Z.le_trans. 2: apply A. xomega. - - xomega. } - assert (C: forall l n, - In (S Outgoing ofs ty) (regs_of_rpairs l) -> - ofs + typesize ty <= fold_left max_outgoing_2 l n). - { induction l; simpl; intros. - - contradiction. - - rewrite in_app_iff in H. destruct H. - + eapply Z.le_trans. eapply B; eauto. apply Z.ge_le. apply fold_max_outgoing_above. - + apply IHl; auto. - } - apply C. -Qed. - Lemma loc_arguments_main: loc_arguments signature_main = nil. Proof. reflexivity. Qed. + +(** ** Normalization of function results *) + +(** No normalization needed. *) + +Definition return_value_needs_normalization (t: rettype) := false. |