Module Machregs


Require Import String.
Require Import Coqlib.
Require Import Decidableplus.
Require Import Maps.
Require Import AST Values Globalenvs.
Require Import Integers.
Require Import Op.

Machine registers


The following type defines the machine registers that can be referenced as locations. These include: The type mreg does not include reserved machine registers such as the zero register (x0), the link register (x1), the stack pointer (x2), the global pointer (x3), and the thread pointer (x4). Finally, register x31 is reserved for use as a temporary by the assembly-code generator Asmgen.

Inductive mreg: Type :=
Allocatable integer regs.
              | R5: mreg | R6: mreg | R7: mreg
  | R8: mreg | R9: mreg | R10: mreg | R11: mreg
  | R12: mreg | R13: mreg | R14: mreg | R15: mreg
  | R16: mreg | R17: mreg | R18: mreg | R19: mreg
  | R20: mreg | R21: mreg | R22: mreg | R23: mreg
  | R24: mreg | R25: mreg | R26: mreg | R27: mreg
  | R28: mreg | R29: mreg | R30: mreg
Allocatable double-precision float regs
  | F0: mreg | F1: mreg | F2: mreg | F3: mreg
  | F4: mreg | F5: mreg | F6: mreg | F7: mreg
  | F8: mreg | F9: mreg | F10: mreg | F11: mreg
  | F12: mreg | F13: mreg | F14: mreg | F15: mreg
  | F16: mreg | F17: mreg | F18: mreg | F19: mreg
  | F20: mreg | F21: mreg | F22: mreg | F23: mreg
  | F24: mreg | F25: mreg | F26: mreg | F27: mreg
  | F28: mreg | F29: mreg | F30: mreg | F31: mreg.

Lemma mreg_eq: forall (r1 r2: mreg), {r1 = r2} + {r1 <> r2}.
Proof.
decide equality. Defined.
Global Opaque mreg_eq.

Definition all_mregs :=
    R5 :: R6 :: R7 :: R8 :: R9 :: R10 :: R11 :: R12 :: R13 :: R14 :: R15
 :: R16 :: R17 :: R18 :: R19 :: R20 :: R21 :: R22 :: R23
 :: R24 :: R25 :: R26 :: R27 :: R28 :: R29 :: R30
 :: F0 :: F1 :: F2 :: F3 :: F4 :: F5 :: F6 :: F7
 :: F8 :: F9 :: F10 :: F11 :: F12 :: F13 :: F14 :: F15
 :: F16 :: F17 :: F18 :: F19 :: F20 :: F21 :: F22 :: F23
 :: F24 :: F25 :: F26 :: F27 :: F28 :: F29 :: F30 :: F31
 :: nil.

Lemma all_mregs_complete:
  forall (r: mreg), In r all_mregs.
Proof.
  assert (forall r, proj_sumbool (In_dec mreg_eq r all_mregs) = true) by (destruct r; reflexivity).
  intros. specialize (H r). InvBooleans. auto.
Qed.

Global Instance Decidable_eq_mreg : forall (x y: mreg), Decidable (eq x y) := Decidable_eq mreg_eq.
  
Global Instance Finite_mreg : Finite mreg := {
  Finite_elements := all_mregs;
  Finite_elements_spec := all_mregs_complete
}.

Definition mreg_type (r: mreg): typ :=
  match r with
        | R5 | R6 | R7 | R8 | R9 | R10 | R11
  | R12 | R13 | R14 | R15 | R16 | R17 | R18 | R19
  | R20 | R21 | R22 | R23 | R24 | R25 | R26 | R27
  | R28 | R29 | R30 => if Archi.ptr64 then Tany64 else Tany32

  | F0 | F1 | F2 | F3 | F4 | F5 | F6 | F7
  | F8 | F9 | F10 | F11 | F12 | F13 | F14 | F15
  | F16 | F17 | F18 | F19 | F20 | F21 | F22 | F23
  | F24 | F25 | F26 | F27 | F28 | F29 | F30 | F31 => Tany64
  end.

Open Scope positive_scope.

Module IndexedMreg <: INDEXED_TYPE.
  Definition t := mreg.
  Definition eq := mreg_eq.
  Definition index (r: mreg): positive :=
    match r with
                | R5 => 1 | R6 => 2 | R7 => 3
    | R8 => 4 | R9 => 5 | R10 => 6 | R11 => 7
    | R12 => 8 | R13 => 9 | R14 => 10 | R15 => 11
    | R16 => 12 | R17 => 13 | R18 => 14 | R19 => 15
    | R20 => 16 | R21 => 17 | R22 => 18 | R23 => 19
    | R24 => 20 | R25 => 21 | R26 => 22 | R27 => 23
    | R28 => 24 | R29 => 25 | R30 => 26

    | F0 => 28 | F1 => 29 | F2 => 30 | F3 => 31
    | F4 => 32 | F5 => 33 | F6 => 34 | F7 => 35
    | F8 => 36 | F9 => 37 | F10 => 38 | F11 => 39
    | F12 => 40 | F13 => 41 | F14 => 42 | F15 => 43
    | F16 => 44 | F17 => 45 | F18 => 46 | F19 => 47
    | F20 => 48 | F21 => 49 | F22 => 50 | F23 => 51
    | F24 => 52 | F25 => 53 | F26 => 54 | F27 => 55
    | F28 => 56 | F29 => 57 | F30 => 58 | F31 => 59
    end.
  Lemma index_inj:
    forall r1 r2, index r1 = index r2 -> r1 = r2.
  Proof.
    decide_goal.
  Qed.
End IndexedMreg.

Definition is_stack_reg (r: mreg) : bool := false.

Names of registers


Local Open Scope string_scope.

Definition register_names :=
                  ("X5", R5) :: ("X6", R6) :: ("X7", R7) ::
  ("X8", R8) :: ("X9", R9) :: ("X10", R10) :: ("X11", R11) ::
  ("X12", R12) :: ("X13", R13) :: ("X14", R14) :: ("X15", R15) ::
  ("X16", R16) :: ("X17", R17) :: ("X18", R18) :: ("X19", R19) ::
  ("X20", R20) :: ("X21", R21) :: ("X22", R22) :: ("X23", R23) ::
  ("X24", R24) :: ("X25", R25) :: ("X26", R26) :: ("X27", R27) ::
  ("X28", R28) :: ("X29", R29) :: ("X30", R30) ::

  ("F0", F0) :: ("F1", F1) :: ("F2", F2) :: ("F3", F3) ::
  ("F4", F4) :: ("F5", F5) :: ("F6", F6) :: ("F7", F7) ::
  ("F8", F8) :: ("F9", F9) :: ("F10", F10) :: ("F11", F11) ::
  ("F12", F12) :: ("F13", F13) :: ("F14", F14) :: ("F15", F15) ::
  ("F16", F16) :: ("F17", F17) :: ("F18", F18) :: ("F19", F19) ::
  ("F20", F20) :: ("F21", F21) :: ("F22", F22) :: ("F23", F23) ::
  ("F24", F24) :: ("F25", F25) :: ("F26", F26) :: ("F27", F27) ::
  ("F28", F28) :: ("F29", F29) :: ("F30", F30) :: ("F31", F31) ::
  nil.

Definition register_by_name (s: string) : option mreg :=
  let fix assoc (l: list (string * mreg)) : option mreg :=
    match l with
    | nil => None
    | (s1, r1) :: l' => if string_dec s s1 then Some r1 else assoc l'
    end
  in assoc register_names.

Destroyed registers, preferred registers


Definition destroyed_by_op (op: operation): list mreg :=
  match op with
  | Ointoffloat | Ointuoffloat | Ointofsingle | Ointuofsingle
  | Olongoffloat | Olonguoffloat | Olongofsingle | Olonguofsingle
      => F6 :: nil
  | _ => nil
  end.

Definition destroyed_by_load (chunk: memory_chunk) (addr: addressing): list mreg := nil.

Definition destroyed_by_store (chunk: memory_chunk) (addr: addressing): list mreg := nil.

Definition destroyed_by_cond (cond: condition): list mreg := nil.

Definition destroyed_by_jumptable: list mreg := R5 :: nil.

Fixpoint destroyed_by_clobber (cl: list string): list mreg :=
  match cl with
  | nil => nil
  | c1 :: cl =>
      match register_by_name c1 with
      | Some r => r :: destroyed_by_clobber cl
      | None => destroyed_by_clobber cl
      end
  end.

Definition destroyed_by_builtin (ef: external_function): list mreg :=
  match ef with
  | EF_inline_asm txt sg clob => destroyed_by_clobber clob
  | EF_memcpy sz al => R5 :: R6 :: R7 :: F0 :: nil
  | EF_builtin name sg =>
      if string_dec name "__builtin_clz"
      || string_dec name "__builtin_clzl"
      || string_dec name "__builtin_clzll" then
        R5 :: R8 :: R9 :: nil
      else if string_dec name "__builtin_ctz"
      || string_dec name "__builtin_ctzl"
      || string_dec name "__builtin_ctzll" then
             R6 :: R8 :: R9 :: nil
      else if string_dec name "__builtin_bswap"
      || string_dec name "__builtin_bswap32"
      || string_dec name "__builtin_bswap64" then R8 :: nil
      else nil
  | _ => nil
  end.

Definition destroyed_by_setstack (ty: typ): list mreg := nil.

Definition destroyed_at_function_entry: list mreg := R30 :: nil.

Definition temp_for_parent_frame: mreg := R30.

Definition destroyed_at_indirect_call: list mreg :=
  R10 :: R11 :: R12 :: R13 :: R14 :: R15 :: R16 :: R17 :: nil.

Definition mregs_for_operation (op: operation): list (option mreg) * option mreg := (nil, None).

Definition mregs_for_builtin (ef: external_function): list (option mreg) * list(option mreg) :=
  match ef with
  | EF_builtin name sg =>
      if (negb Archi.ptr64) && string_dec name "__builtin_bswap64" then
        (Some R6 :: Some R5 :: nil, Some R5 :: Some R6 :: nil)
      else if string_dec name "__builtin_clz"
           || string_dec name "__builtin_clzl" then
        (Some R5 :: nil, Some R7 :: nil)
      else if string_dec name "__builtin_clzll" then
        if Archi.ptr64
        then (Some R5 :: nil, Some R7 :: nil)
        else (Some R6 :: Some R5 :: nil, Some R7 :: nil)
      else if string_dec name "__builtin_ctz"
           || string_dec name "__builtin_ctzl" then
        (Some R6 :: nil, Some R7 :: nil)
      else if string_dec name "__builtin_ctzll" then
        if Archi.ptr64
        then (Some R6 :: nil, Some R7 :: nil)
        else (Some R6 :: Some R5 :: nil, Some R7 :: nil)
      else
        (nil, nil)
  | _ =>
    (nil, nil)
  end.

Global Opaque
    destroyed_by_op destroyed_by_load destroyed_by_store
    destroyed_by_cond destroyed_by_jumptable destroyed_by_builtin
    destroyed_by_setstack destroyed_at_function_entry temp_for_parent_frame
    mregs_for_operation mregs_for_builtin.

Two-address operations. Return true if the first argument and the result must be in the same location *and* are unconstrained by mregs_for_operation. There are five: the pseudo Ocast32signed, because it expands to a no-op owing to the representation of 32-bit integers as their 64-bit sign extension; Ocast32unsigned, because it builds on the same magic no-op; the Ocopy, Ocopyimm, and Owelldef pseudo instructions that also expand to a no-op.

Definition two_address_op (op: operation) : bool :=
  match op with
  | Ocopy | Ocopyimm _ | Owelldef _
  | Ocast32signed | Ocast32unsigned => true
  | _ => false
  end.

Constraints on constant propagation for builtins

Definition builtin_constraints (ef: external_function) :
                                       list builtin_arg_constraint :=
  match ef with
  | EF_builtin id sg => nil
  | EF_vload _ => OK_addressing :: nil
  | EF_vstore _ => OK_addressing :: OK_default :: nil
  | EF_memcpy _ _ => OK_addrstack :: OK_addrstack :: nil
  | EF_annot kind txt targs => map (fun _ => OK_all) targs
  | EF_debug kind txt targs => map (fun _ => OK_all) targs
  | _ => nil
  end.

Definition builtin_destroys_ra : external_function -> list (builtin_arg mreg) -> builtin_res mreg -> bool :=
  fun _ _ _ => true.

Linear typing


Definition wt_linear_special_op op args res : bool :=
  match op, args with
  | Omove, arg :: nil
  | Ocopyimm _, arg :: nil =>
      subtype (mreg_type arg) (mreg_type res)
  | Ocopy, arg1 :: arg2 :: nil =>
      subtype (mreg_type arg1) (mreg_type res)
  | _, _ => false
  end.

Lemma special_op_linear_type_preservation {F V} (ge: Genv.t F V) :
  forall op args res sp m vargs v,
  eval_operation ge sp op vargs m = Some v ->
  list_forall2 (fun v r => Val.has_type v (mreg_type r)) vargs args ->
  wt_linear_special_op op args res = true ->
  Val.has_type v (mreg_type res).
Proof.
  intros [] * EVAL WTARGS WT; simpl in *; try congruence.
  all:repeat (destruct args as [|? args]; simpl in *; try congruence; []).
  all:repeat (match goal with
              | H: list_forall2 _ _ (_::_) |- _ => inv H
              | H: list_forall2 _ _ nil |- _ => inv H
              | H: Some _ = Some _ |- _ => inv H
              end); eauto using Val.has_subtype.
Qed.
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