(**************************************************************************)
(*                                                                        *)
(*                                 OCaml                                  *)
(*                                                                        *)
(*             Xavier Leroy, projet Cristal, INRIA Rocquencourt           *)
(*                                                                        *)
(*   Copyright 1996 Institut National de Recherche en Informatique et     *)
(*     en Automatique.                                                    *)
(*                                                                        *)
(*   All rights reserved.  This file is distributed under the terms of    *)
(*   the GNU Lesser General Public License version 2.1, with the          *)
(*   special exception on linking described in the file LICENSE.          *)
(*                                                                        *)
(**************************************************************************)

(* Description of primitive functions *)

open Misc
open Parsetree

type boxed_integer = Pnativeint | Pint32 | Pint64

type native_repr =
  | Same_as_ocaml_repr
  | Unboxed_float
  | Unboxed_integer of boxed_integer
  | Untagged_int

type description =
  { prim_name: string;         (* Name of primitive  or C function *)
    prim_arity: int;           (* Number of arguments *)
    prim_alloc: bool;          (* Does it allocates or raise? *)
    prim_native_name: string;  (* Name of C function for the nat. code gen. *)
    prim_native_repr_args: native_repr list;
    prim_native_repr_res: native_repr }

type error =
  | Old_style_float_with_native_repr_attribute
  | Old_style_noalloc_with_noalloc_attribute
  | No_native_primitive_with_repr_attribute

exception Error of Location.t * error

let is_ocaml_repr = function
  | Same_as_ocaml_repr -> true
  | Unboxed_float
  | Unboxed_integer _
  | Untagged_int -> false

let is_unboxed = function
  | Same_as_ocaml_repr
  | Untagged_int -> false
  | Unboxed_float
  | Unboxed_integer _ -> true

let is_untagged = function
  | Untagged_int -> true
  | Same_as_ocaml_repr
  | Unboxed_float
  | Unboxed_integer _ -> false

let rec make_native_repr_args arity x =
  if arity = 0 then
    []
  else
    x :: make_native_repr_args (arity - 1) x

let simple ~name ~arity ~alloc =
  {prim_name = name;
   prim_arity = arity;
   prim_alloc = alloc;
   prim_native_name = "";
   prim_native_repr_args = make_native_repr_args arity Same_as_ocaml_repr;
   prim_native_repr_res = Same_as_ocaml_repr}

let make ~name ~alloc ~native_name ~native_repr_args ~native_repr_res =
  {prim_name = name;
   prim_arity = List.length native_repr_args;
   prim_alloc = alloc;
   prim_native_name = native_name;
   prim_native_repr_args = native_repr_args;
   prim_native_repr_res = native_repr_res}

let parse_declaration valdecl ~native_repr_args ~native_repr_res =
  let arity = List.length native_repr_args in
  let name, native_name, old_style_noalloc, old_style_float =
    match valdecl.pval_prim with
    | name :: "noalloc" :: name2 :: "float" :: _ -> (name, name2, true, true)
    | name :: "noalloc" :: name2 :: _ -> (name, name2, true, false)
    | name :: name2 :: "float" :: _ -> (name, name2, false, true)
    | name :: "noalloc" :: _ -> (name, "", true, false)
    | name :: name2 :: _ -> (name, name2, false, false)
    | name :: _ -> (name, "", false, false)
    | [] ->
        fatal_error "Primitive.parse_declaration"
  in
  let noalloc_attribute =
    Attr_helper.has_no_payload_attribute ["noalloc"; "ocaml.noalloc"]
      valdecl.pval_attributes
  in
  if old_style_float &&
     not (List.for_all is_ocaml_repr native_repr_args &&
          is_ocaml_repr native_repr_res) then
    raise (Error (valdecl.pval_loc,
                  Old_style_float_with_native_repr_attribute));
  if old_style_noalloc && noalloc_attribute then
    raise (Error (valdecl.pval_loc,
                  Old_style_noalloc_with_noalloc_attribute));
  (* The compiler used to assume "noalloc" with "float", we just make this
     explicit now (GPR#167): *)
  let old_style_noalloc = old_style_noalloc || old_style_float in
  if old_style_float then
    Location.deprecated valdecl.pval_loc
      "[@@unboxed] + [@@noalloc] should be used\n\
       instead of \"float\""
  else if old_style_noalloc then
    Location.deprecated valdecl.pval_loc
      "[@@noalloc] should be used instead of \"noalloc\"";
  if native_name = "" &&
     not (List.for_all is_ocaml_repr native_repr_args &&
          is_ocaml_repr native_repr_res) then
    raise (Error (valdecl.pval_loc,
                  No_native_primitive_with_repr_attribute));
  let noalloc = old_style_noalloc || noalloc_attribute in
  let native_repr_args, native_repr_res =
    if old_style_float then
      (make_native_repr_args arity Unboxed_float, Unboxed_float)
    else
      (native_repr_args, native_repr_res)
  in
  {prim_name = name;
   prim_arity = arity;
   prim_alloc = not noalloc;
   prim_native_name = native_name;
   prim_native_repr_args = native_repr_args;
   prim_native_repr_res = native_repr_res}

open Outcometree

let rec add_native_repr_attributes ty attrs =
  match ty, attrs with
  | Otyp_arrow (label, a, b), attr_opt :: rest ->
    let b = add_native_repr_attributes b rest in
    let a =
      match attr_opt with
      | None -> a
      | Some attr -> Otyp_attribute (a, attr)
    in
    Otyp_arrow (label, a, b)
  | _, [Some attr] -> Otyp_attribute (ty, attr)
  | _ ->
    assert (List.for_all (fun x -> x = None) attrs);
    ty

let oattr_unboxed = { oattr_name = "unboxed" }
let oattr_untagged = { oattr_name = "untagged" }
let oattr_noalloc = { oattr_name = "noalloc" }

let print p osig_val_decl =
  let prims =
    if p.prim_native_name <> "" then
      [p.prim_name; p.prim_native_name]
    else
      [p.prim_name]
  in
  let for_all f =
    List.for_all f p.prim_native_repr_args && f p.prim_native_repr_res
  in
  let all_unboxed = for_all is_unboxed in
  let all_untagged = for_all is_untagged in
  let attrs = if p.prim_alloc then [] else [oattr_noalloc] in
  let attrs =
    if all_unboxed then
      oattr_unboxed :: attrs
    else if all_untagged then
      oattr_untagged :: attrs
    else
      attrs
  in
  let attr_of_native_repr = function
    | Same_as_ocaml_repr -> None
    | Unboxed_float
    | Unboxed_integer _ -> if all_unboxed then None else Some oattr_unboxed
    | Untagged_int -> if all_untagged then None else Some oattr_untagged
  in
  let type_attrs =
    List.map attr_of_native_repr p.prim_native_repr_args @
    [attr_of_native_repr p.prim_native_repr_res]
  in
  { osig_val_decl with
    oval_prims = prims;
    oval_type = add_native_repr_attributes osig_val_decl.oval_type type_attrs;
    oval_attributes = attrs }

let native_name p =
  if p.prim_native_name <> ""
  then p.prim_native_name
  else p.prim_name

let byte_name p =
  p.prim_name

let native_name_is_external p =
  let nat_name = native_name p in
  nat_name <> "" && nat_name.[0] <> '%'

let report_error ppf err =
  match err with
  | Old_style_float_with_native_repr_attribute ->
    Format.fprintf ppf "Cannot use \"float\" in conjunction with \
                        [%@unboxed]/[%@untagged]."
  | Old_style_noalloc_with_noalloc_attribute ->
    Format.fprintf ppf "Cannot use \"noalloc\" in conjunction with \
                        [%@%@noalloc]."
  | No_native_primitive_with_repr_attribute ->
    Format.fprintf ppf
      "[@The native code version of the primitive is mandatory@ \
       when attributes [%@untagged] or [%@unboxed] are present.@]"

let () =
  Location.register_error_of_exn
    (function
      | Error (loc, err) ->
        Some (Location.error_of_printer ~loc report_error err)
      | _ ->
        None
    )