Source file script_interpreter.ml

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(*

  This module implements an interpreter for Michelson. It takes the
  form of a [step] function that interprets script instructions in a
  dedicated abstract machine.

  The interpreter is written in a small-step style: an execution
  [step] only interprets a single instruction by updating the
  configuration of a dedicated abstract machine.

  This abstract machine has two components:

  - a stack to control which instructions must be executed ; and

  - a stack of values where instructions get their inputs and put
   their outputs.

  In addition, the machine has access to effectful primitives to
  interact with the execution environment (e.g. the Tezos
  node). These primitives live in the [Lwt+State+Error] monad. Hence,
  this interpreter produces a computation in the [Lwt+State+Error]
  monad.

  This interpreter enjoys the following properties:

  - The interpreter is tail-recursive, hence it is robust to stack
    overflow. This property is checked by the compiler thanks to the
    [@ocaml.tailcall] annotation of each recursive call.

  - The interpreter is type-preserving. Thanks to GADTs, the typing
    rules of Michelson are statically checked by the OCaml typechecker:
    a Michelson program cannot go wrong.

  - The interpreter is tagless. Thanks to GADTs, the exact shape of
    the stack is known statically so the interpreter does not have to
    check that the input stack has the shape expected by the
    instruction to be executed.

  Outline
  =======

  This file is organized as follows:

  1. Definition of runtime errors.

  2. Interpretation loop: This is the main functionality of this
   module, aka the [step] function.

  3. Interface functions: This part of the module builds high-level
   functions on top of the more basic [step] function.

  Auxiliary definitions can be found in {!Script_interpreter_defs}.

  Implementation details are explained along the file.

*)

open Alpha_context
open Script_typed_ir
open Script_ir_translator
open Local_gas_counter
open Script_interpreter_defs
module S = Saturation_repr

type step_constants = Script_typed_ir.step_constants = {
  source : Contract.t;
  payer : Signature.public_key_hash;
  self : Contract_hash.t;
  amount : Tez.t;
  balance : Tez.t;
  chain_id : Chain_id.t;
  now : Script_timestamp.t;
  level : Script_int.n Script_int.num;
}

(* ---- Run-time errors -----------------------------------------------------*)

type error += Reject of Script.location * Script.expr * execution_trace option

type error += Overflow of Script.location * execution_trace option

type error += Runtime_contract_error of Contract_hash.t

type error += Bad_contract_parameter of Contract.t (* `Permanent *)

type error += Cannot_serialize_failure

type error += Cannot_serialize_storage

type error += Michelson_too_many_recursive_calls

let () =
  let open Data_encoding in
  let trace_encoding =
    list
    @@ obj3
         (req "location" Script.location_encoding)
         (req "gas" Gas.encoding)
         (req "stack" (list Script.expr_encoding))
  in
  (* Reject *)
  register_error_kind
    `Temporary
    ~id:"michelson_v1.script_rejected"
    ~title:"Script failed"
    ~description:"A FAILWITH instruction was reached"
    (obj3
       (req "location" Script.location_encoding)
       (req "with" Script.expr_encoding)
       (opt "trace" trace_encoding))
    (function Reject (loc, v, trace) -> Some (loc, v, trace) | _ -> None)
    (fun (loc, v, trace) -> Reject (loc, v, trace)) ;
  (* Overflow *)
  register_error_kind
    `Temporary
    ~id:"michelson_v1.script_overflow"
    ~title:"Script failed (overflow error)"
    ~description:
      "A FAIL instruction was reached due to the detection of an overflow"
    (obj2
       (req "location" Script.location_encoding)
       (opt "trace" trace_encoding))
    (function Overflow (loc, trace) -> Some (loc, trace) | _ -> None)
    (fun (loc, trace) -> Overflow (loc, trace)) ;
  (* Runtime contract error *)
  register_error_kind
    `Temporary
    ~id:"michelson_v1.runtime_error"
    ~title:"Script runtime error"
    ~description:"Toplevel error for all runtime script errors"
    (obj2
       (req "contract_handle" Contract.originated_encoding)
       (req "contract_code" (constant "Deprecated")))
    (function
      | Runtime_contract_error contract -> Some (contract, ()) | _ -> None)
    (fun (contract, ()) -> Runtime_contract_error contract) ;
  (* Bad contract parameter *)
  register_error_kind
    `Permanent
    ~id:"michelson_v1.bad_contract_parameter"
    ~title:"Contract supplied an invalid parameter"
    ~description:
      "Either no parameter was supplied to a contract with a non-unit \
       parameter type, a non-unit parameter was passed to an account, or a \
       parameter was supplied of the wrong type"
    Data_encoding.(obj1 (req "contract" Contract.encoding))
    (function Bad_contract_parameter c -> Some c | _ -> None)
    (fun c -> Bad_contract_parameter c) ;
  (* Cannot serialize failure *)
  register_error_kind
    `Temporary
    ~id:"michelson_v1.cannot_serialize_failure"
    ~title:"Not enough gas to serialize argument of FAILWITH"
    ~description:
      "Argument of FAILWITH was too big to be serialized with the provided gas"
    Data_encoding.empty
    (function Cannot_serialize_failure -> Some () | _ -> None)
    (fun () -> Cannot_serialize_failure) ;
  (* Cannot serialize storage *)
  register_error_kind
    `Temporary
    ~id:"michelson_v1.cannot_serialize_storage"
    ~title:"Not enough gas to serialize execution storage"
    ~description:
      "The returned storage was too big to be serialized with the provided gas"
    Data_encoding.empty
    (function Cannot_serialize_storage -> Some () | _ -> None)
    (fun () -> Cannot_serialize_storage)

(*

  Interpretation loop
  ===================

*)

(*

   As announced earlier, the [step] function produces a computation in
   the [Lwt+State+Error] monad. The [State] monad is implemented by
   having the [context] passed as input and returned updated as
   output. The [Error] monad is represented by the [tzresult] type
   constructor.

   The [step] function is actually defined as an internal
   tail-recursive routine of the toplevel [step]. It monitors the gas
   level before executing the instruction under focus, once this is
   done, it recursively calls itself on the continuation held by the
   current instruction.

   For each pure instruction (i.e. that is not monadic), the
   interpretation simply updates the input arguments of the [step]
   function. Since these arguments are (most likely) stored in
   hardware registers and since the tail-recursive calls are compiled
   into direct jumps, this interpretation technique offers good
   performances while saving safety thanks to a rich typing.

   For each impure instruction, the interpreter makes use of monadic
   bindings to compose monadic primitives with the [step] function.
   Again, we make sure that the recursive calls to [step] are tail
   calls by annotating them with [@ocaml.tailcall].

   The [step] function is actually based on several mutually
   recursive functions that can be separated in two groups: the first
   group focuses on the evaluation of continuations while the second
   group is about evaluating the instructions.

*)

(*

    Evaluation of continuations
    ===========================

    As explained in [Script_typed_ir], there are several kinds of
    continuations, each having a specific evaluation rules. The
    following group of functions starts with a list of evaluation
    rules for continuations that generate fresh continuations. This
    group ends with the definition of [next], which dispatches
    evaluation rules depending on the continuation at stake.

   Some of these functions generate fresh continuations. As such, they
   expect a constructor [instrument] which inserts a [KLog] if the
   evaluation is logged.

 *)
let rec kmap_exit :
    type a b c e f m n o. (a, b, c, e, f, m, n, o) kmap_exit_type =
 fun instrument g gas body xs ty ys yk ks accu stack ->
  let ys = Script_map.update yk (Some accu) ys in
  let ks = instrument @@ KMap_enter_body (body, xs, ys, ty, ks) in
  let accu, stack = stack in
  (next [@ocaml.tailcall]) g gas ks accu stack
 [@@inline]

and kmap_enter : type a b c d f i j k. (a, b, c, d, f, i, j, k) kmap_enter_type
    =
 fun instrument g gas body xs ty ys ks accu stack ->
  match xs with
  | [] -> (next [@ocaml.tailcall]) g gas ks ys (accu, stack)
  | (xk, xv) :: xs ->
      let ks = instrument @@ KMap_exit_body (body, xs, ys, xk, ty, ks) in
      let res = (xk, xv) in
      let stack = (accu, stack) in
      (step [@ocaml.tailcall]) g gas body ks res stack
 [@@inline]

and klist_exit : type a b c d e i j. (a, b, c, d, e, i, j) klist_exit_type =
 fun instrument g gas body xs ys ty len ks accu stack ->
  let ks = instrument @@ KList_enter_body (body, xs, accu :: ys, ty, len, ks) in
  let accu, stack = stack in
  (next [@ocaml.tailcall]) g gas ks accu stack
 [@@inline]

and klist_enter : type a b c d e f j. (a, b, c, d, e, f, j) klist_enter_type =
 fun instrument g gas body xs ys ty len ks' accu stack ->
  match xs with
  | [] ->
      let ys = {elements = List.rev ys; length = len} in
      (next [@ocaml.tailcall]) g gas ks' ys (accu, stack)
  | x :: xs ->
      let ks = instrument @@ KList_exit_body (body, xs, ys, ty, len, ks') in
      (step [@ocaml.tailcall]) g gas body ks x (accu, stack)
 [@@inline]

and kloop_in_left : type a b c d e f g. (a, b, c, d, e, f, g) kloop_in_left_type
    =
 fun g gas ks0 ki ks' accu stack ->
  match accu with
  | L v -> (step [@ocaml.tailcall]) g gas ki ks0 v stack
  | R v -> (next [@ocaml.tailcall]) g gas ks' v stack
 [@@inline]

and kloop_in : type a b c r f s. (a, b, c, r, f, s) kloop_in_type =
 fun g gas ks0 ki ks' accu stack ->
  let accu', stack' = stack in
  if accu then (step [@ocaml.tailcall]) g gas ki ks0 accu' stack'
  else (next [@ocaml.tailcall]) g gas ks' accu' stack'
 [@@inline]

and kiter : type a b s r f c. (a, b, s, r, f, c) kiter_type =
 fun instrument g gas body ty xs ks accu stack ->
  match xs with
  | [] -> (next [@ocaml.tailcall]) g gas ks accu stack
  | x :: xs ->
      let ks = instrument @@ KIter (body, ty, xs, ks) in
      (step [@ocaml.tailcall]) g gas body ks x (accu, stack)
 [@@inline]

and next :
    type a s r f.
    outdated_context * step_constants ->
    local_gas_counter ->
    (a, s, r, f) continuation ->
    a ->
    s ->
    (r * f * outdated_context * local_gas_counter) tzresult Lwt.t =
 fun ((ctxt, _) as g) gas ks0 accu stack ->
  match consume_control gas ks0 with
  | None -> fail Gas.Operation_quota_exceeded
  | Some gas -> (
      match ks0 with
      | KLog (ks, sty, logger) ->
          (klog [@ocaml.tailcall]) logger g gas sty ks0 ks accu stack
      | KNil -> Lwt.return (Ok (accu, stack, ctxt, gas))
      | KCons (k, ks) -> (step [@ocaml.tailcall]) g gas k ks accu stack
      | KLoop_in (ki, ks') ->
          (kloop_in [@ocaml.tailcall]) g gas ks0 ki ks' accu stack
      | KReturn (stack', _, ks) -> (next [@ocaml.tailcall]) g gas ks accu stack'
      | KMap_head (f, ks) -> (next [@ocaml.tailcall]) g gas ks (f accu) stack
      | KLoop_in_left (ki, ks') ->
          (kloop_in_left [@ocaml.tailcall]) g gas ks0 ki ks' accu stack
      | KUndip (x, _, ks) -> (next [@ocaml.tailcall]) g gas ks x (accu, stack)
      | KIter (body, ty, xs, ks) ->
          (kiter [@ocaml.tailcall]) id g gas body ty xs ks accu stack
      | KList_enter_body (body, xs, ys, ty, len, ks) ->
          (klist_enter [@ocaml.tailcall])
            id
            g
            gas
            body
            xs
            ys
            ty
            len
            ks
            accu
            stack
      | KList_exit_body (body, xs, ys, ty, len, ks) ->
          (klist_exit [@ocaml.tailcall])
            id
            g
            gas
            body
            xs
            ys
            ty
            len
            ks
            accu
            stack
      | KMap_enter_body (body, xs, ys, ty, ks) ->
          (kmap_enter [@ocaml.tailcall]) id g gas body xs ty ys ks accu stack
      | KMap_exit_body (body, xs, ys, yk, ty, ks) ->
          (kmap_exit [@ocaml.tailcall]) id g gas body xs ty ys yk ks accu stack
      | KView_exit (orig_step_constants, ks) ->
          let g = (fst g, orig_step_constants) in
          (next [@ocaml.tailcall]) g gas ks accu stack)

(*

   Evaluation of instructions
   ==========================

   The following functions define evaluation rules for instructions that
   generate fresh continuations. As such, they expect a constructor
   [instrument] which inserts a [KLog] if the evaluation is logged.

   The [step] function is taking care of the evaluation of the other
   instructions.

*)
and ilist_map :
    type a b c d e f g h i. (a, b, c, d, e, f, g, h, i) ilist_map_type =
 fun instrument g gas body k ks ty accu stack ->
  let xs = accu.elements in
  let ys = [] in
  let len = accu.length in
  let ks =
    instrument @@ KList_enter_body (body, xs, ys, ty, len, KCons (k, ks))
  in
  let accu, stack = stack in
  (next [@ocaml.tailcall]) g gas ks accu stack
 [@@inline]

and ilist_iter :
    type a b c d e f g cmp. (a, b, c, d, e, f, g, cmp) ilist_iter_type =
 fun instrument g gas body ty k ks accu stack ->
  let xs = accu.elements in
  let ks = instrument @@ KIter (body, ty, xs, KCons (k, ks)) in
  let accu, stack = stack in
  (next [@ocaml.tailcall]) g gas ks accu stack
 [@@inline]

and iset_iter : type a b c d e f g. (a, b, c, d, e, f, g) iset_iter_type =
 fun instrument g gas body ty k ks accu stack ->
  let set = accu in
  let l = List.rev (Script_set.fold (fun e acc -> e :: acc) set []) in
  let ks = instrument @@ KIter (body, ty, l, KCons (k, ks)) in
  let accu, stack = stack in
  (next [@ocaml.tailcall]) g gas ks accu stack
 [@@inline]

and imap_map :
    type a b c d e f g h i j. (a, b, c, d, e, f, g, h, i, j) imap_map_type =
 fun instrument g gas body k ks ty accu stack ->
  let map = accu in
  let xs = List.rev (Script_map.fold (fun k v a -> (k, v) :: a) map []) in
  let ys = Script_map.empty_from map in
  let ks = instrument @@ KMap_enter_body (body, xs, ys, ty, KCons (k, ks)) in
  let accu, stack = stack in
  (next [@ocaml.tailcall]) g gas ks accu stack
 [@@inline]

and imap_iter :
    type a b c d e f g h cmp. (a, b, c, d, e, f, g, h, cmp) imap_iter_type =
 fun instrument g gas body ty k ks accu stack ->
  let map = accu in
  let l = List.rev (Script_map.fold (fun k v a -> (k, v) :: a) map []) in
  let ks = instrument @@ KIter (body, ty, l, KCons (k, ks)) in
  let accu, stack = stack in
  (next [@ocaml.tailcall]) g gas ks accu stack
 [@@inline]

and imul_teznat : type a b c d e f. (a, b, c, d, e, f) imul_teznat_type =
 fun logger g gas loc k ks accu stack ->
  let x = accu in
  let y, stack = stack in
  match Script_int.to_int64 y with
  | None -> get_log logger >>=? fun log -> fail (Overflow (loc, log))
  | Some y ->
      Tez.(x *? y) >>?= fun res -> (step [@ocaml.tailcall]) g gas k ks res stack

and imul_nattez : type a b c d e f. (a, b, c, d, e, f) imul_nattez_type =
 fun logger g gas loc k ks accu stack ->
  let y = accu in
  let x, stack = stack in
  match Script_int.to_int64 y with
  | None -> get_log logger >>=? fun log -> fail (Overflow (loc, log))
  | Some y ->
      Tez.(x *? y) >>?= fun res -> (step [@ocaml.tailcall]) g gas k ks res stack

and ilsl_nat : type a b c d e f. (a, b, c, d, e, f) ilsl_nat_type =
 fun logger g gas loc k ks accu stack ->
  let x = accu and y, stack = stack in
  match Script_int.shift_left_n x y with
  | None -> get_log logger >>=? fun log -> fail (Overflow (loc, log))
  | Some x -> (step [@ocaml.tailcall]) g gas k ks x stack

and ilsr_nat : type a b c d e f. (a, b, c, d, e, f) ilsr_nat_type =
 fun logger g gas loc k ks accu stack ->
  let x = accu and y, stack = stack in
  match Script_int.shift_right_n x y with
  | None -> get_log logger >>=? fun log -> fail (Overflow (loc, log))
  | Some r -> (step [@ocaml.tailcall]) g gas k ks r stack

and ifailwith : ifailwith_type =
  {
    ifailwith =
      (fun logger (ctxt, _) gas kloc tv accu ->
        let v = accu in
        let ctxt = update_context gas ctxt in
        trace Cannot_serialize_failure (unparse_data ctxt Optimized tv v)
        >>=? fun (v, _ctxt) ->
        get_log logger >>=? fun log -> fail (Reject (kloc, v, log)));
  }

and iexec : type a b c d e f g. (a, b, c, d, e, f, g) iexec_type =
 fun instrument logger g gas cont_sty k ks accu stack ->
  let arg = accu and code, stack = stack in
  let log_code b =
    let body =
      match logger with
      | None -> b.kinstr
      | Some logger ->
          Script_interpreter_logging.log_kinstr logger b.kbef b.kinstr
    in
    let ks = instrument @@ KReturn (stack, cont_sty, KCons (k, ks)) in
    (body, ks)
  in
  match code with
  | Lam (body, _) ->
      let body, ks = log_code body in
      (step [@ocaml.tailcall]) g gas body ks arg (EmptyCell, EmptyCell)
  | LamRec (body, _) ->
      let body, ks = log_code body in
      (step [@ocaml.tailcall]) g gas body ks arg (code, (EmptyCell, EmptyCell))

and iview : type a b c d e f i o. (a, b, c, d, e, f, i, o) iview_type =
 fun instrument
     (ctxt, sc)
     gas
     (View_signature {name; input_ty; output_ty})
     stack_ty
     k
     ks
     accu
     stack ->
  let input = accu in
  let addr, stack = stack in
  let ctxt = update_context gas ctxt in
  let return_none ctxt =
    let gas, ctxt = local_gas_counter_and_outdated_context ctxt in
    (step [@ocaml.tailcall]) (ctxt, sc) gas k ks None stack
  in
  let legacy = Script_ir_translator_config.make ~legacy:true () in
  match addr.destination with
  | Contract (Implicit _) | Tx_rollup _ | Sc_rollup _ | Zk_rollup _ ->
      (return_none [@ocaml.tailcall]) ctxt
  | Contract (Originated contract_hash as c) -> (
      Contract.get_script ctxt contract_hash >>=? fun (ctxt, script_opt) ->
      match script_opt with
      | None -> (return_none [@ocaml.tailcall]) ctxt
      | Some script -> (
          parse_script
            ~elab_conf:legacy
            ~allow_forged_in_storage:true
            ctxt
            script
          >>=? fun (Ex_script (Script {storage; storage_type; views; _}), ctxt)
            ->
          Gas.consume ctxt (Interp_costs.view_get name views) >>?= fun ctxt ->
          match Script_map.get name views with
          | None -> (return_none [@ocaml.tailcall]) ctxt
          | Some view -> (
              let view_result =
                Script_ir_translator.parse_view
                  ctxt
                  ~elab_conf:legacy
                  storage_type
                  view
              in
              trace_eval
                (fun () ->
                  Script_tc_errors.Ill_typed_contract
                    (Micheline.strip_locations view.view_code, []))
                view_result
              >>=? fun ( Typed_view
                           {
                             input_ty = input_ty';
                             output_ty = output_ty';
                             kinstr;
                             original_code_expr = _;
                           },
                         ctxt ) ->
              let io_ty =
                let open Gas_monad.Syntax in
                let* out_eq = ty_eq ~error_details:Fast output_ty' output_ty in
                let+ in_eq = ty_eq ~error_details:Fast input_ty input_ty' in
                (out_eq, in_eq)
              in
              Gas_monad.run ctxt io_ty >>?= fun (eq, ctxt) ->
              match eq with
              | Error Inconsistent_types_fast ->
                  (return_none [@ocaml.tailcall]) ctxt
              | Ok (Eq, Eq) ->
                  let kcons = KCons (ICons_some (kinstr_location k, k), ks) in
                  Contract.get_balance_carbonated ctxt c
                  >>=? fun (ctxt, balance) ->
                  let gas, ctxt = local_gas_counter_and_outdated_context ctxt in
                  let sty =
                    Option.map (fun t -> Item_t (output_ty, t)) stack_ty
                  in
                  (step [@ocaml.tailcall])
                    ( ctxt,
                      {
                        source = Contract.Originated sc.self;
                        self = contract_hash;
                        amount = Tez.zero;
                        balance;
                        (* The following remain unchanged, but let's
                           list them anyway, so that we don't forget
                           to update something added later. *)
                        payer = sc.payer;
                        chain_id = sc.chain_id;
                        now = sc.now;
                        level = sc.level;
                      } )
                    gas
                    kinstr
                    (instrument @@ KView_exit (sc, KReturn (stack, sty, kcons)))
                    (input, storage)
                    (EmptyCell, EmptyCell))))

and step : type a s b t r f. (a, s, b, t, r, f) step_type =
 fun ((ctxt, sc) as g) gas i ks accu stack ->
  match consume_instr gas i accu stack with
  | None -> fail Gas.Operation_quota_exceeded
  | Some gas -> (
      match i with
      | ILog (_, sty, event, logger, k) ->
          (log [@ocaml.tailcall]) (logger, event) sty g gas k ks accu stack
      | IHalt _ -> (next [@ocaml.tailcall]) g gas ks accu stack
      (* stack ops *)
      | IDrop (_, k) ->
          let accu, stack = stack in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IDup (_, k) -> (step [@ocaml.tailcall]) g gas k ks accu (accu, stack)
      | ISwap (_, k) ->
          let top, stack = stack in
          (step [@ocaml.tailcall]) g gas k ks top (accu, stack)
      | IConst (_, _ty, v, k) ->
          (step [@ocaml.tailcall]) g gas k ks v (accu, stack)
      (* options *)
      | ICons_some (_, k) ->
          (step [@ocaml.tailcall]) g gas k ks (Some accu) stack
      | ICons_none (_, _ty, k) ->
          (step [@ocaml.tailcall]) g gas k ks None (accu, stack)
      | IIf_none {branch_if_none; branch_if_some; k; _} -> (
          match accu with
          | None ->
              let accu, stack = stack in
              (step [@ocaml.tailcall])
                g
                gas
                branch_if_none
                (KCons (k, ks))
                accu
                stack
          | Some v ->
              (step [@ocaml.tailcall])
                g
                gas
                branch_if_some
                (KCons (k, ks))
                v
                stack)
      | IOpt_map {body; k; loc = _} -> (
          match accu with
          | None -> (step [@ocaml.tailcall]) g gas k ks None stack
          | Some v ->
              let ks' = KMap_head (Option.some, KCons (k, ks)) in
              (step [@ocaml.tailcall]) g gas body ks' v stack)
      (* pairs *)
      | ICons_pair (_, k) ->
          let b, stack = stack in
          (step [@ocaml.tailcall]) g gas k ks (accu, b) stack
      | IUnpair (_, k) ->
          let a, b = accu in
          (step [@ocaml.tailcall]) g gas k ks a (b, stack)
      | ICar (_, k) ->
          let a, _ = accu in
          (step [@ocaml.tailcall]) g gas k ks a stack
      | ICdr (_, k) ->
          let _, b = accu in
          (step [@ocaml.tailcall]) g gas k ks b stack
      (* unions *)
      | ICons_left (_, _tyb, k) ->
          (step [@ocaml.tailcall]) g gas k ks (L accu) stack
      | ICons_right (_, _tya, k) ->
          (step [@ocaml.tailcall]) g gas k ks (R accu) stack
      | IIf_left {branch_if_left; branch_if_right; k; _} -> (
          match accu with
          | L v ->
              (step [@ocaml.tailcall])
                g
                gas
                branch_if_left
                (KCons (k, ks))
                v
                stack
          | R v ->
              (step [@ocaml.tailcall])
                g
                gas
                branch_if_right
                (KCons (k, ks))
                v
                stack)
      (* lists *)
      | ICons_list (_, k) ->
          let tl, stack = stack in
          let accu = Script_list.cons accu tl in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | INil (_, _ty, k) ->
          let stack = (accu, stack) in
          let accu = Script_list.empty in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IIf_cons {branch_if_cons; branch_if_nil; k; _} -> (
          match accu.elements with
          | [] ->
              let accu, stack = stack in
              (step [@ocaml.tailcall])
                g
                gas
                branch_if_nil
                (KCons (k, ks))
                accu
                stack
          | hd :: tl ->
              let tl = {elements = tl; length = accu.length - 1} in
              (step [@ocaml.tailcall])
                g
                gas
                branch_if_cons
                (KCons (k, ks))
                hd
                (tl, stack))
      | IList_map (_, body, ty, k) ->
          (ilist_map [@ocaml.tailcall]) id g gas body k ks ty accu stack
      | IList_size (_, k) ->
          let list = accu in
          let len = Script_int.(abs (of_int list.length)) in
          (step [@ocaml.tailcall]) g gas k ks len stack
      | IList_iter (_, ty, body, k) ->
          (ilist_iter [@ocaml.tailcall]) id g gas body ty k ks accu stack
      (* sets *)
      | IEmpty_set (_, ty, k) ->
          let res = Script_set.empty ty in
          let stack = (accu, stack) in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | ISet_iter (_, ty, body, k) ->
          (iset_iter [@ocaml.tailcall]) id g gas body ty k ks accu stack
      | ISet_mem (_, k) ->
          let set, stack = stack in
          let res = Script_set.mem accu set in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | ISet_update (_, k) ->
          let presence, (set, stack) = stack in
          let res = Script_set.update accu presence set in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | ISet_size (_, k) ->
          let res = Script_set.size accu in
          (step [@ocaml.tailcall]) g gas k ks res stack
      (* maps *)
      | IEmpty_map (_, kty, _vty, k) ->
          let res = Script_map.empty kty and stack = (accu, stack) in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IMap_map (_, ty, body, k) ->
          (imap_map [@ocaml.tailcall]) id g gas body k ks ty accu stack
      | IMap_iter (_, kvty, body, k) ->
          (imap_iter [@ocaml.tailcall]) id g gas body kvty k ks accu stack
      | IMap_mem (_, k) ->
          let map, stack = stack in
          let res = Script_map.mem accu map in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IMap_get (_, k) ->
          let map, stack = stack in
          let res = Script_map.get accu map in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IMap_update (_, k) ->
          let v, (map, stack) = stack in
          let key = accu in
          let res = Script_map.update key v map in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IMap_get_and_update (_, k) ->
          let key = accu in
          let v, (map, rest) = stack in
          let map' = Script_map.update key v map in
          let v' = Script_map.get key map in
          (step [@ocaml.tailcall]) g gas k ks v' (map', rest)
      | IMap_size (_, k) ->
          let res = Script_map.size accu in
          (step [@ocaml.tailcall]) g gas k ks res stack
      (* Big map operations *)
      | IEmpty_big_map (_, tk, tv, k) ->
          let ebm = Script_big_map.empty tk tv in
          (step [@ocaml.tailcall]) g gas k ks ebm (accu, stack)
      | IBig_map_mem (_, k) ->
          let map, stack = stack in
          let key = accu in
          ( use_gas_counter_in_context ctxt gas @@ fun ctxt ->
            Script_big_map.mem ctxt key map )
          >>=? fun (res, ctxt, gas) ->
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks res stack
      | IBig_map_get (_, k) ->
          let map, stack = stack in
          let key = accu in
          ( use_gas_counter_in_context ctxt gas @@ fun ctxt ->
            Script_big_map.get ctxt key map )
          >>=? fun (res, ctxt, gas) ->
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks res stack
      | IBig_map_update (_, k) ->
          let key = accu in
          let maybe_value, (map, stack) = stack in
          ( use_gas_counter_in_context ctxt gas @@ fun ctxt ->
            Script_big_map.update ctxt key maybe_value map )
          >>=? fun (big_map, ctxt, gas) ->
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks big_map stack
      | IBig_map_get_and_update (_, k) ->
          let key = accu in
          let v, (map, stack) = stack in
          ( use_gas_counter_in_context ctxt gas @@ fun ctxt ->
            Script_big_map.get_and_update ctxt key v map )
          >>=? fun ((v', map'), ctxt, gas) ->
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks v' (map', stack)
      (* timestamp operations *)
      | IAdd_seconds_to_timestamp (_, k) ->
          let n = accu in
          let t, stack = stack in
          let result = Script_timestamp.add_delta t n in
          (step [@ocaml.tailcall]) g gas k ks result stack
      | IAdd_timestamp_to_seconds (_, k) ->
          let t = accu in
          let n, stack = stack in
          let result = Script_timestamp.add_delta t n in
          (step [@ocaml.tailcall]) g gas k ks result stack
      | ISub_timestamp_seconds (_, k) ->
          let t = accu in
          let s, stack = stack in
          let result = Script_timestamp.sub_delta t s in
          (step [@ocaml.tailcall]) g gas k ks result stack
      | IDiff_timestamps (_, k) ->
          let t1 = accu in
          let t2, stack = stack in
          let result = Script_timestamp.diff t1 t2 in
          (step [@ocaml.tailcall]) g gas k ks result stack
      (* string operations *)
      | IConcat_string_pair (_, k) ->
          let x = accu in
          let y, stack = stack in
          let s = Script_string.concat_pair x y in
          (step [@ocaml.tailcall]) g gas k ks s stack
      | IConcat_string (_, k) ->
          let ss = accu in
          (* The cost for this fold_left has been paid upfront *)
          let total_length =
            List.fold_left
              (fun acc s -> S.add acc (S.safe_int (Script_string.length s)))
              S.zero
              ss.elements
          in
          consume gas (Interp_costs.concat_string total_length) >>?= fun gas ->
          let s = Script_string.concat ss.elements in
          (step [@ocaml.tailcall]) g gas k ks s stack
      | ISlice_string (_, k) ->
          let offset = accu and length, (s, stack) = stack in
          let s_length = Z.of_int (Script_string.length s) in
          let offset = Script_int.to_zint offset in
          let length = Script_int.to_zint length in
          if Compare.Z.(offset < s_length && Z.add offset length <= s_length)
          then
            let s = Script_string.sub s (Z.to_int offset) (Z.to_int length) in
            (step [@ocaml.tailcall]) g gas k ks (Some s) stack
          else (step [@ocaml.tailcall]) g gas k ks None stack
      | IString_size (_, k) ->
          let s = accu in
          let result = Script_int.(abs (of_int (Script_string.length s))) in
          (step [@ocaml.tailcall]) g gas k ks result stack
      (* bytes operations *)
      | IConcat_bytes_pair (_, k) ->
          let x = accu in
          let y, stack = stack in
          let s = Bytes.cat x y in
          (step [@ocaml.tailcall]) g gas k ks s stack
      | IConcat_bytes (_, k) ->
          let ss = accu in
          (* The cost for this fold_left has been paid upfront *)
          let total_length =
            List.fold_left
              (fun acc s -> S.add acc (S.safe_int (Bytes.length s)))
              S.zero
              ss.elements
          in
          consume gas (Interp_costs.concat_string total_length) >>?= fun gas ->
          let s = Bytes.concat Bytes.empty ss.elements in
          (step [@ocaml.tailcall]) g gas k ks s stack
      | ISlice_bytes (_, k) ->
          let offset = accu and length, (s, stack) = stack in
          let s_length = Z.of_int (Bytes.length s) in
          let offset = Script_int.to_zint offset in
          let length = Script_int.to_zint length in
          if Compare.Z.(offset < s_length && Z.add offset length <= s_length)
          then
            let s = Bytes.sub s (Z.to_int offset) (Z.to_int length) in
            (step [@ocaml.tailcall]) g gas k ks (Some s) stack
          else (step [@ocaml.tailcall]) g gas k ks None stack
      | IBytes_size (_, k) ->
          let s = accu in
          let result = Script_int.(abs (of_int (Bytes.length s))) in
          (step [@ocaml.tailcall]) g gas k ks result stack
      (* currency operations *)
      | IAdd_tez (_, k) ->
          let x = accu in
          let y, stack = stack in
          Tez.(x +? y) >>?= fun res ->
          (step [@ocaml.tailcall]) g gas k ks res stack
      | ISub_tez (_, k) ->
          let x = accu in
          let y, stack = stack in
          let res = Tez.sub_opt x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | ISub_tez_legacy (_, k) ->
          let x = accu in
          let y, stack = stack in
          Tez.(x -? y) >>?= fun res ->
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IMul_teznat (loc, k) -> imul_teznat None g gas loc k ks accu stack
      | IMul_nattez (loc, k) -> imul_nattez None g gas loc k ks accu stack
      (* boolean operations *)
      | IOr (_, k) ->
          let x = accu in
          let y, stack = stack in
          (step [@ocaml.tailcall]) g gas k ks (x || y) stack
      | IAnd (_, k) ->
          let x = accu in
          let y, stack = stack in
          (step [@ocaml.tailcall]) g gas k ks (x && y) stack
      | IXor (_, k) ->
          let x = accu in
          let y, stack = stack in
          let res = Compare.Bool.(x <> y) in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | INot (_, k) ->
          let x = accu in
          (step [@ocaml.tailcall]) g gas k ks (not x) stack
      (* integer operations *)
      | IIs_nat (_, k) ->
          let x = accu in
          let res = Script_int.is_nat x in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IAbs_int (_, k) ->
          let x = accu in
          let res = Script_int.abs x in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IInt_nat (_, k) ->
          let x = accu in
          let res = Script_int.int x in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | INeg (_, k) ->
          let x = accu in
          let res = Script_int.neg x in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IAdd_int (_, k) ->
          let x = accu and y, stack = stack in
          let res = Script_int.add x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IAdd_nat (_, k) ->
          let x = accu and y, stack = stack in
          let res = Script_int.add_n x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | ISub_int (_, k) ->
          let x = accu and y, stack = stack in
          let res = Script_int.sub x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IMul_int (_, k) ->
          let x = accu and y, stack = stack in
          let res = Script_int.mul x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IMul_nat (_, k) ->
          let x = accu and y, stack = stack in
          let res = Script_int.mul_n x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IEdiv_teznat (_, k) ->
          let x = accu and y, stack = stack in
          let x = Script_int.of_int64 (Tez.to_mutez x) in
          let result =
            match Script_int.ediv x y with
            | None -> None
            | Some (q, r) -> (
                match (Script_int.to_int64 q, Script_int.to_int64 r) with
                | Some q, Some r -> (
                    match (Tez.of_mutez q, Tez.of_mutez r) with
                    | Some q, Some r -> Some (q, r)
                    (* Cannot overflow *)
                    | _ -> assert false)
                (* Cannot overflow *)
                | _ -> assert false)
          in
          (step [@ocaml.tailcall]) g gas k ks result stack
      | IEdiv_tez (_, k) ->
          let x = accu and y, stack = stack in
          let x = Script_int.abs (Script_int.of_int64 (Tez.to_mutez x)) in
          let y = Script_int.abs (Script_int.of_int64 (Tez.to_mutez y)) in
          let result =
            match Script_int.ediv_n x y with
            | None -> None
            | Some (q, r) -> (
                match Script_int.to_int64 r with
                | None -> assert false (* Cannot overflow *)
                | Some r -> (
                    match Tez.of_mutez r with
                    | None -> assert false (* Cannot overflow *)
                    | Some r -> Some (q, r)))
          in
          (step [@ocaml.tailcall]) g gas k ks result stack
      | IEdiv_int (_, k) ->
          let x = accu and y, stack = stack in
          let res = Script_int.ediv x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IEdiv_nat (_, k) ->
          let x = accu and y, stack = stack in
          let res = Script_int.ediv_n x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | ILsl_nat (loc, k) -> ilsl_nat None g gas loc k ks accu stack
      | ILsr_nat (loc, k) -> ilsr_nat None g gas loc k ks accu stack
      | IOr_nat (_, k) ->
          let x = accu and y, stack = stack in
          let res = Script_int.logor x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IAnd_nat (_, k) ->
          let x = accu and y, stack = stack in
          let res = Script_int.logand x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IAnd_int_nat (_, k) ->
          let x = accu and y, stack = stack in
          let res = Script_int.logand x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IXor_nat (_, k) ->
          let x = accu and y, stack = stack in
          let res = Script_int.logxor x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | INot_int (_, k) ->
          let x = accu in
          let res = Script_int.lognot x in
          (step [@ocaml.tailcall]) g gas k ks res stack
      (* control *)
      | IIf {branch_if_true; branch_if_false; k; _} ->
          let res, stack = stack in
          if accu then
            (step [@ocaml.tailcall])
              g
              gas
              branch_if_true
              (KCons (k, ks))
              res
              stack
          else
            (step [@ocaml.tailcall])
              g
              gas
              branch_if_false
              (KCons (k, ks))
              res
              stack
      | ILoop (_, body, k) ->
          let ks = KLoop_in (body, KCons (k, ks)) in
          (next [@ocaml.tailcall]) g gas ks accu stack
      | ILoop_left (_, bl, br) ->
          let ks = KLoop_in_left (bl, KCons (br, ks)) in
          (next [@ocaml.tailcall]) g gas ks accu stack
      | IDip (_, b, ty, k) ->
          let ign = accu in
          let ks = KUndip (ign, ty, KCons (k, ks)) in
          let accu, stack = stack in
          (step [@ocaml.tailcall]) g gas b ks accu stack
      | IExec (_, sty, k) -> iexec id None g gas sty k ks accu stack
      | IApply (_, capture_ty, k) ->
          let capture = accu in
          let lam, stack = stack in
          apply ctxt gas capture_ty capture lam >>=? fun (lam', ctxt, gas) ->
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks lam' stack
      | ILambda (_, lam, k) ->
          (step [@ocaml.tailcall]) g gas k ks lam (accu, stack)
      | IFailwith (kloc, tv) ->
          let {ifailwith} = ifailwith in
          ifailwith None g gas kloc tv accu
      (* comparison *)
      | ICompare (_, ty, k) ->
          let a = accu in
          let b, stack = stack in
          let r =
            Script_int.of_int @@ Script_comparable.compare_comparable ty a b
          in
          (step [@ocaml.tailcall]) g gas k ks r stack
      (* comparators *)
      | IEq (_, k) ->
          let a = accu in
          let a = Script_int.compare a Script_int.zero in
          let a = Compare.Int.(a = 0) in
          (step [@ocaml.tailcall]) g gas k ks a stack
      | INeq (_, k) ->
          let a = accu in
          let a = Script_int.compare a Script_int.zero in
          let a = Compare.Int.(a <> 0) in
          (step [@ocaml.tailcall]) g gas k ks a stack
      | ILt (_, k) ->
          let a = accu in
          let a = Script_int.compare a Script_int.zero in
          let a = Compare.Int.(a < 0) in
          (step [@ocaml.tailcall]) g gas k ks a stack
      | ILe (_, k) ->
          let a = accu in
          let a = Script_int.compare a Script_int.zero in
          let a = Compare.Int.(a <= 0) in
          (step [@ocaml.tailcall]) g gas k ks a stack
      | IGt (_, k) ->
          let a = accu in
          let a = Script_int.compare a Script_int.zero in
          let a = Compare.Int.(a > 0) in
          (step [@ocaml.tailcall]) g gas k ks a stack
      | IGe (_, k) ->
          let a = accu in
          let a = Script_int.compare a Script_int.zero in
          let a = Compare.Int.(a >= 0) in
          (step [@ocaml.tailcall]) g gas k ks a stack
      (* packing *)
      | IPack (_, ty, k) ->
          let value = accu in
          ( use_gas_counter_in_context ctxt gas @@ fun ctxt ->
            Script_ir_translator.pack_data ctxt ty value )
          >>=? fun (bytes, ctxt, gas) ->
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks bytes stack
      | IUnpack (_, ty, k) ->
          let bytes = accu in
          ( use_gas_counter_in_context ctxt gas @@ fun ctxt ->
            unpack ctxt ~ty ~bytes )
          >>=? fun (opt, ctxt, gas) ->
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks opt stack
      | IAddress (_, k) ->
          let typed_contract = accu in
          let destination = Typed_contract.destination typed_contract in
          let entrypoint = Typed_contract.entrypoint typed_contract in
          let address = {destination; entrypoint} in
          (step [@ocaml.tailcall]) g gas k ks address stack
      | IContract (loc, t, entrypoint, k) -> (
          let addr = accu in
          let entrypoint_opt =
            if Entrypoint.is_default addr.entrypoint then Some entrypoint
            else if Entrypoint.is_default entrypoint then Some addr.entrypoint
            else (* both entrypoints are non-default *) None
          in
          match entrypoint_opt with
          | Some entrypoint ->
              let ctxt = update_context gas ctxt in
              Script_ir_translator.parse_contract_for_script
                ctxt
                loc
                t
                addr.destination
                ~entrypoint
              >>=? fun (ctxt, maybe_contract) ->
              let gas, ctxt = local_gas_counter_and_outdated_context ctxt in
              let accu = maybe_contract in
              (step [@ocaml.tailcall]) (ctxt, sc) gas k ks accu stack
          | None -> (step [@ocaml.tailcall]) (ctxt, sc) gas k ks None stack)
      | ITransfer_tokens (loc, k) ->
          let p = accu in
          let amount, (typed_contract, stack) = stack in
          transfer (ctxt, sc) gas amount loc typed_contract p
          >>=? fun (accu, ctxt, gas) ->
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks accu stack
      | IImplicit_account (_, k) ->
          let key = accu in
          let res = Typed_implicit key in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IView (_, view_signature, stack_ty, k) ->
          (iview [@ocaml.tailcall])
            id
            g
            gas
            view_signature
            stack_ty
            k
            ks
            accu
            stack
      | ICreate_contract {storage_type; code; k; loc = _} ->
          (* Removed the instruction's arguments manager, spendable and delegatable *)
          let delegate = accu in
          let credit, (init, stack) = stack in
          create_contract g gas storage_type code delegate credit init
          >>=? fun (res, contract, ctxt, gas) ->
          let destination = Destination.Contract (Originated contract) in
          let stack = ({destination; entrypoint = Entrypoint.default}, stack) in
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks res stack
      | ISet_delegate (_, k) ->
          let delegate = accu in
          let operation = Delegation delegate in
          let ctxt = update_context gas ctxt in
          fresh_internal_nonce ctxt >>?= fun (ctxt, nonce) ->
          let piop =
            Internal_operation
              {source = Contract.Originated sc.self; operation; nonce}
          in
          let res = {piop; lazy_storage_diff = None} in
          let gas, ctxt = local_gas_counter_and_outdated_context ctxt in
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks res stack
      | IBalance (_, k) ->
          let ctxt = update_context gas ctxt in
          let gas, ctxt = local_gas_counter_and_outdated_context ctxt in
          let g = (ctxt, sc) in
          (step [@ocaml.tailcall]) g gas k ks sc.balance (accu, stack)
      | ILevel (_, k) ->
          (step [@ocaml.tailcall]) g gas k ks sc.level (accu, stack)
      | INow (_, k) -> (step [@ocaml.tailcall]) g gas k ks sc.now (accu, stack)
      | IMin_block_time (_, k) ->
          let ctxt = update_context gas ctxt in
          let min_block_time =
            Alpha_context.Constants.minimal_block_delay ctxt
            |> Period.to_seconds |> Script_int.of_int64
            (* Realistically the block delay is never negative. *)
            |> Script_int.abs
          in
          let new_stack = (accu, stack) in
          (step [@ocaml.tailcall]) g gas k ks min_block_time new_stack
      | ICheck_signature (_, k) ->
          let key = accu and signature, (message, stack) = stack in
          let res = Script_signature.check key signature message in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IHash_key (_, k) ->
          let key = accu in
          let res = Signature.Public_key.hash key in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IBlake2b (_, k) ->
          let bytes = accu in
          let hash = Raw_hashes.blake2b bytes in
          (step [@ocaml.tailcall]) g gas k ks hash stack
      | ISha256 (_, k) ->
          let bytes = accu in
          let hash = Raw_hashes.sha256 bytes in
          (step [@ocaml.tailcall]) g gas k ks hash stack
      | ISha512 (_, k) ->
          let bytes = accu in
          let hash = Raw_hashes.sha512 bytes in
          (step [@ocaml.tailcall]) g gas k ks hash stack
      | ISource (_, k) ->
          let destination : Destination.t = Contract (Implicit sc.payer) in
          let res = {destination; entrypoint = Entrypoint.default} in
          (step [@ocaml.tailcall]) g gas k ks res (accu, stack)
      | ISender (_, k) ->
          let destination : Destination.t = Contract sc.source in
          let res = {destination; entrypoint = Entrypoint.default} in
          (step [@ocaml.tailcall]) g gas k ks res (accu, stack)
      | ISelf (_, ty, entrypoint, k) ->
          let res =
            Typed_originated {arg_ty = ty; contract_hash = sc.self; entrypoint}
          in
          (step [@ocaml.tailcall]) g gas k ks res (accu, stack)
      | ISelf_address (_, k) ->
          let destination : Destination.t = Contract (Originated sc.self) in
          let res = {destination; entrypoint = Entrypoint.default} in
          (step [@ocaml.tailcall]) g gas k ks res (accu, stack)
      | IAmount (_, k) ->
          let accu = sc.amount and stack = (accu, stack) in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IDig (_, _n, n', k) ->
          let (accu, stack), x =
            interp_stack_prefix_preserving_operation
              (fun v stack -> (stack, v))
              n'
              accu
              stack
          in
          let accu = x and stack = (accu, stack) in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IDug (_, _n, n', k) ->
          let v = accu in
          let accu, stack = stack in
          let (accu, stack), () =
            interp_stack_prefix_preserving_operation
              (fun accu stack -> ((v, (accu, stack)), ()))
              n'
              accu
              stack
          in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IDipn (_, _n, n', b, k) ->
          let accu, stack, restore_prefix = kundip n' accu stack k in
          let ks = KCons (restore_prefix, ks) in
          (step [@ocaml.tailcall]) g gas b ks accu stack
      | IDropn (_, _n, n', k) ->
          let stack =
            let rec aux :
                type a s b t.
                (b, t, b, t, a, s, a, s) stack_prefix_preservation_witness ->
                a ->
                s ->
                b * t =
             fun w accu stack ->
              match w with
              | KRest -> (accu, stack)
              | KPrefix (_, _ty, w) ->
                  let accu, stack = stack in
                  aux w accu stack
            in
            aux n' accu stack
          in
          let accu, stack = stack in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | ISapling_empty_state (_, memo_size, k) ->
          let state = Sapling.empty_state ~memo_size () in
          (step [@ocaml.tailcall]) g gas k ks state (accu, stack)
      | ISapling_verify_update (_, k) -> (
          let transaction = accu in
          let state, stack = stack in
          let address = Contract_hash.to_b58check sc.self in
          let sc_chain_id = Script_chain_id.make sc.chain_id in
          let chain_id = Script_chain_id.to_b58check sc_chain_id in
          let anti_replay = address ^ chain_id in
          let ctxt = update_context gas ctxt in
          Sapling.verify_update ctxt state transaction anti_replay
          >>=? fun (ctxt, balance_state_opt) ->
          let gas, ctxt = local_gas_counter_and_outdated_context ctxt in
          match balance_state_opt with
          | Some (balance, state) ->
              let state =
                Some
                  ( Bytes.of_string transaction.bound_data,
                    (Script_int.of_int64 balance, state) )
              in
              (step [@ocaml.tailcall]) (ctxt, sc) gas k ks state stack
          | None -> (step [@ocaml.tailcall]) (ctxt, sc) gas k ks None stack)
      | ISapling_verify_update_deprecated (_, k) -> (
          let transaction = accu in
          let state, stack = stack in
          let address = Contract_hash.to_b58check sc.self in
          let sc_chain_id = Script_chain_id.make sc.chain_id in
          let chain_id = Script_chain_id.to_b58check sc_chain_id in
          let anti_replay = address ^ chain_id in
          let ctxt = update_context gas ctxt in
          Sapling.Legacy.verify_update ctxt state transaction anti_replay
          >>=? fun (ctxt, balance_state_opt) ->
          let gas, ctxt = local_gas_counter_and_outdated_context ctxt in
          match balance_state_opt with
          | Some (balance, state) ->
              let state = Some (Script_int.of_int64 balance, state) in
              (step [@ocaml.tailcall]) (ctxt, sc) gas k ks state stack
          | None -> (step [@ocaml.tailcall]) (ctxt, sc) gas k ks None stack)
      | IChainId (_, k) ->
          let accu = Script_chain_id.make sc.chain_id
          and stack = (accu, stack) in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | INever _ -> ( match accu with _ -> .)
      | IVoting_power (_, k) ->
          let key_hash = accu in
          let ctxt = update_context gas ctxt in
          Vote.get_voting_power ctxt key_hash >>=? fun (ctxt, power) ->
          let power = Script_int.(abs (of_int64 power)) in
          let gas, ctxt = local_gas_counter_and_outdated_context ctxt in
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks power stack
      | ITotal_voting_power (_, k) ->
          let ctxt = update_context gas ctxt in
          Vote.get_total_voting_power ctxt >>=? fun (ctxt, power) ->
          let power = Script_int.(abs (of_int64 power)) in
          let gas, ctxt = local_gas_counter_and_outdated_context ctxt in
          let g = (ctxt, sc) in
          (step [@ocaml.tailcall]) g gas k ks power (accu, stack)
      | IKeccak (_, k) ->
          let bytes = accu in
          let hash = Raw_hashes.keccak256 bytes in
          (step [@ocaml.tailcall]) g gas k ks hash stack
      | ISha3 (_, k) ->
          let bytes = accu in
          let hash = Raw_hashes.sha3_256 bytes in
          (step [@ocaml.tailcall]) g gas k ks hash stack
      | IAdd_bls12_381_g1 (_, k) ->
          let x = accu and y, stack = stack in
          let accu = Script_bls.G1.add x y in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IAdd_bls12_381_g2 (_, k) ->
          let x = accu and y, stack = stack in
          let accu = Script_bls.G2.add x y in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IAdd_bls12_381_fr (_, k) ->
          let x = accu and y, stack = stack in
          let accu = Script_bls.Fr.add x y in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IMul_bls12_381_g1 (_, k) ->
          let x = accu and y, stack = stack in
          let accu = Script_bls.G1.mul x y in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IMul_bls12_381_g2 (_, k) ->
          let x = accu and y, stack = stack in
          let accu = Script_bls.G2.mul x y in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IMul_bls12_381_fr (_, k) ->
          let x = accu and y, stack = stack in
          let accu = Script_bls.Fr.mul x y in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IMul_bls12_381_fr_z (_, k) ->
          let x = accu and y, stack = stack in
          let x = Script_bls.Fr.of_z (Script_int.to_zint x) in
          let res = Script_bls.Fr.mul x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IMul_bls12_381_z_fr (_, k) ->
          let y = accu and x, stack = stack in
          let x = Script_bls.Fr.of_z (Script_int.to_zint x) in
          let res = Script_bls.Fr.mul x y in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | IInt_bls12_381_fr (_, k) ->
          let x = accu in
          let res = Script_int.of_zint (Script_bls.Fr.to_z x) in
          (step [@ocaml.tailcall]) g gas k ks res stack
      | INeg_bls12_381_g1 (_, k) ->
          let x = accu in
          let accu = Script_bls.G1.negate x in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | INeg_bls12_381_g2 (_, k) ->
          let x = accu in
          let accu = Script_bls.G2.negate x in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | INeg_bls12_381_fr (_, k) ->
          let x = accu in
          let accu = Script_bls.Fr.negate x in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IPairing_check_bls12_381 (_, k) ->
          let pairs = accu in
          let check = Script_bls.pairing_check pairs.elements in
          (step [@ocaml.tailcall]) g gas k ks check stack
      | IComb (_, _, witness, k) ->
          let rec aux :
              type a b s c d t.
              (a, b, s, c, d, t) comb_gadt_witness -> a * (b * s) -> c * (d * t)
              =
           fun witness stack ->
            match (witness, stack) with
            | Comb_one, stack -> stack
            | Comb_succ witness', (a, tl) ->
                let b, tl' = aux witness' tl in
                ((a, b), tl')
          in
          let stack = aux witness (accu, stack) in
          let accu, stack = stack in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IUncomb (_, _, witness, k) ->
          let rec aux :
              type a b s c d t.
              (a, b, s, c, d, t) uncomb_gadt_witness ->
              a * (b * s) ->
              c * (d * t) =
           fun witness stack ->
            match (witness, stack) with
            | Uncomb_one, stack -> stack
            | Uncomb_succ witness', ((a, b), tl) -> (a, aux witness' (b, tl))
          in
          let stack = aux witness (accu, stack) in
          let accu, stack = stack in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IComb_get (_, _, witness, k) ->
          let comb = accu in
          let rec aux :
              type before after.
              (before, after) comb_get_gadt_witness -> before -> after =
           fun witness comb ->
            match (witness, comb) with
            | Comb_get_zero, v -> v
            | Comb_get_one, (a, _) -> a
            | Comb_get_plus_two witness', (_, b) -> aux witness' b
          in
          let accu = aux witness comb in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IComb_set (_, _, witness, k) ->
          let value = accu and comb, stack = stack in
          let rec aux :
              type value before after.
              (value, before, after) comb_set_gadt_witness ->
              value ->
              before ->
              after =
           fun witness value item ->
            match (witness, item) with
            | Comb_set_zero, _ -> value
            | Comb_set_one, (_hd, tl) -> (value, tl)
            | Comb_set_plus_two witness', (hd, tl) -> (hd, aux witness' value tl)
          in
          let accu = aux witness value comb in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IDup_n (_, _, witness, k) ->
          let rec aux :
              type a b before after.
              (a, b, before, after) dup_n_gadt_witness ->
              a * (b * before) ->
              after =
           fun witness stack ->
            match (witness, stack) with
            | Dup_n_zero, (a, _) -> a
            | Dup_n_succ witness', (_, tl) -> aux witness' tl
          in
          let stack = (accu, stack) in
          let accu = aux witness stack in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      (* Tickets *)
      | ITicket_deprecated (_, _, k) -> (
          let contents = accu and amount, stack = stack in
          match Ticket_amount.of_n amount with
          | Some amount ->
              let ticketer = Contract.Originated sc.self in
              let accu = {ticketer; contents; amount} in
              (step [@ocaml.tailcall]) g gas k ks accu stack
          | None -> fail Script_tc_errors.Forbidden_zero_ticket_quantity)
      | ITicket (_, _, k) -> (
          let contents = accu and amount, stack = stack in
          match Ticket_amount.of_n amount with
          | Some amount ->
              let ticketer = Contract.Originated sc.self in
              let accu = Some {ticketer; contents; amount} in
              (step [@ocaml.tailcall]) g gas k ks accu stack
          | None -> (step [@ocaml.tailcall]) g gas k ks None stack)
      | IRead_ticket (_, _, k) ->
          let {ticketer; contents; amount} = accu in
          let stack = (accu, stack) in
          let destination : Destination.t = Contract ticketer in
          let addr = {destination; entrypoint = Entrypoint.default} in
          let accu =
            (addr, (contents, (amount :> Script_int.n Script_int.num)))
          in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | ISplit_ticket (_, k) ->
          let ticket = accu and (amount_a, amount_b), stack = stack in
          let result =
            Option.bind (Ticket_amount.of_n amount_a) @@ fun amount_a ->
            Option.bind (Ticket_amount.of_n amount_b) @@ fun amount_b ->
            let amount = Ticket_amount.add amount_a amount_b in
            if
              Compare.Int.(
                Script_int.(compare (amount :> n num) (ticket.amount :> n num))
                = 0)
            then
              Some
                ( {ticket with amount = amount_a},
                  {ticket with amount = amount_b} )
            else None
          in
          (step [@ocaml.tailcall]) g gas k ks result stack
      | IJoin_tickets (_, contents_ty, k) ->
          let ticket_a, ticket_b = accu in
          let result =
            if
              Compare.Int.(
                Contract.compare ticket_a.ticketer ticket_b.ticketer = 0
                && Script_comparable.compare_comparable
                     contents_ty
                     ticket_a.contents
                     ticket_b.contents
                   = 0)
            then
              Some
                {
                  ticketer = ticket_a.ticketer;
                  contents = ticket_a.contents;
                  amount = Ticket_amount.add ticket_a.amount ticket_b.amount;
                }
            else None
          in
          (step [@ocaml.tailcall]) g gas k ks result stack
      | IOpen_chest (_, k) ->
          let open Timelock in
          let chest_key = accu in
          let chest, (time_z, stack) = stack in
          (* If the time is not an integer we then consider the proof as
             incorrect. Indeed the verification asks for an integer for practical reasons.
             Therefore no proof can be correct.*)
          let accu =
            match Script_int.to_int time_z with
            | None -> R false
            | Some time -> (
                match Script_timelock.open_chest chest chest_key ~time with
                | Correct bytes -> L bytes
                | Bogus_cipher -> R false
                | Bogus_opening -> R true)
          in
          (step [@ocaml.tailcall]) g gas k ks accu stack
      | IEmit {tag; ty = event_type; unparsed_ty; k; loc = _} ->
          let event_data = accu in
          emit_event (ctxt, sc) gas ~event_type ~unparsed_ty ~tag ~event_data
          >>=? fun (accu, ctxt, gas) ->
          (step [@ocaml.tailcall]) (ctxt, sc) gas k ks accu stack)

(*

  Zero-cost logging
  =================

*)

(*

   The following functions insert a logging instruction to continue
   the logging process in the next execution steps.

   There is a special treatment of instructions that generate fresh
   continuations: we pass a constructor as argument to their
   evaluation rules so that they can instrument these fresh
   continuations by themselves. Instructions that create continuations
   without calling specialised functions have their branches from [step]
   function duplicated and adjusted here.

   This on-the-fly instrumentation of the execution allows zero-cost
   logging since logging instructions are only introduced if an
   initial logging continuation is pushed in the initial continuation
   that starts the evaluation.

*)
and log :
    type a s b t r f.
    logger * logging_event -> (a, s) stack_ty -> (a, s, b, t, r, f) step_type =
 fun (logger, event) sty ((ctxt, _) as g) gas k ks accu stack ->
  (match (k, event) with
  | ILog _, LogEntry -> ()
  | _, LogEntry ->
      Script_interpreter_logging.log_entry logger ctxt gas k sty accu stack
  | _, LogExit prev_loc ->
      Script_interpreter_logging.log_exit
        logger
        ctxt
        gas
        prev_loc
        k
        sty
        accu
        stack) ;
  Script_interpreter_logging.log_next_kinstr logger sty k >>?= fun k ->
  (* We need to match on instructions that create continuations so
     that we can instrument those continuations with [KLog] (see
     comment above).  For functions that don't do this, we simply call
     [step], as they don't require any special treatment. *)
  match k with
  | IIf_none {branch_if_none; branch_if_some; k; _} -> (
      let (Item_t (Option_t (ty, _, _), rest)) = sty in
      Script_interpreter_logging.branched_final_stack_type
        [
          Ex_init_stack_ty (rest, branch_if_none);
          Ex_init_stack_ty (Item_t (ty, rest), branch_if_some);
        ]
      >>?= fun sty_opt ->
      let ks' =
        match sty_opt with
        | None -> KCons (k, ks)
        | Some sty' ->
            Script_interpreter_logging.instrument_cont logger sty'
            @@ KCons (k, ks)
      in
      match accu with
      | None ->
          let accu, stack = stack in
          (step [@ocaml.tailcall]) g gas branch_if_none ks' accu stack
      | Some v -> (step [@ocaml.tailcall]) g gas branch_if_some ks' v stack)
  | IOpt_map {body; k; loc = _} -> (
      match accu with
      | None -> (step [@ocaml.tailcall]) g gas k ks None stack
      | Some v ->
          let (Item_t (Option_t (ty, _, _), rest)) = sty in
          let bsty = Item_t (ty, rest) in
          let kmap_head = KMap_head (Option.some, KCons (k, ks)) in
          Script_interpreter_logging.kinstr_final_stack_type bsty body
          >>?= fun sty_opt ->
          let ks' =
            match sty_opt with
            | None -> kmap_head
            | Some sty' ->
                Script_interpreter_logging.instrument_cont logger sty' kmap_head
          in
          (step [@ocaml.tailcall]) g gas body ks' v stack)
  | IIf_left {branch_if_left; branch_if_right; k; _} -> (
      let (Item_t (Union_t (lty, rty, _, _), rest)) = sty in
      Script_interpreter_logging.branched_final_stack_type
        [
          Ex_init_stack_ty (Item_t (lty, rest), branch_if_left);
          Ex_init_stack_ty (Item_t (rty, rest), branch_if_right);
        ]
      >>?= fun sty_opt ->
      let k' =
        match sty_opt with
        | None -> KCons (k, ks)
        | Some sty' ->
            Script_interpreter_logging.instrument_cont logger sty'
            @@ KCons (k, ks)
      in
      match accu with
      | L v -> (step [@ocaml.tailcall]) g gas branch_if_left k' v stack
      | R v -> (step [@ocaml.tailcall]) g gas branch_if_right k' v stack)
  | IIf_cons {branch_if_cons; branch_if_nil; k; _} -> (
      let (Item_t ((List_t (elty, _) as lty), rest)) = sty in
      Script_interpreter_logging.branched_final_stack_type
        [
          Ex_init_stack_ty (rest, branch_if_nil);
          Ex_init_stack_ty (Item_t (elty, Item_t (lty, rest)), branch_if_cons);
        ]
      >>?= fun sty' ->
      let k' =
        match sty' with
        | None -> KCons (k, ks)
        | Some sty' ->
            Script_interpreter_logging.instrument_cont logger sty'
            @@ KCons (k, ks)
      in
      match accu.elements with
      | [] ->
          let accu, stack = stack in
          (step [@ocaml.tailcall]) g gas branch_if_nil k' accu stack
      | hd :: tl ->
          let tl = {elements = tl; length = accu.length - 1} in
          (step [@ocaml.tailcall]) g gas branch_if_cons k' hd (tl, stack))
  | IList_map (_, body, ty, k) ->
      let (Item_t (_, sty')) = sty in
      let instrument = Script_interpreter_logging.instrument_cont logger sty' in
      (ilist_map [@ocaml.tailcall]) instrument g gas body k ks ty accu stack
  | IList_iter (_, ty, body, k) ->
      let (Item_t (_, sty')) = sty in
      let instrument = Script_interpreter_logging.instrument_cont logger sty' in
      (ilist_iter [@ocaml.tailcall]) instrument g gas body ty k ks accu stack
  | ISet_iter (_, ty, body, k) ->
      let (Item_t (_, rest)) = sty in
      let instrument = Script_interpreter_logging.instrument_cont logger rest in
      (iset_iter [@ocaml.tailcall]) instrument g gas body ty k ks accu stack
  | IMap_map (_, ty, body, k) ->
      let (Item_t (_, rest)) = sty in
      let instrument = Script_interpreter_logging.instrument_cont logger rest in
      (imap_map [@ocaml.tailcall]) instrument g gas body k ks ty accu stack
  | IMap_iter (_, kvty, body, k) ->
      let (Item_t (_, rest)) = sty in
      let instrument = Script_interpreter_logging.instrument_cont logger rest in
      (imap_iter [@ocaml.tailcall]) instrument g gas body kvty k ks accu stack
  | IMul_teznat (loc, k) ->
      (imul_teznat [@ocaml.tailcall]) (Some logger) g gas loc k ks accu stack
  | IMul_nattez (loc, k) ->
      (imul_nattez [@ocaml.tailcall]) (Some logger) g gas loc k ks accu stack
  | ILsl_nat (loc, k) ->
      (ilsl_nat [@ocaml.tailcall]) (Some logger) g gas loc k ks accu stack
  | ILsr_nat (loc, k) ->
      (ilsr_nat [@ocaml.tailcall]) (Some logger) g gas loc k ks accu stack
  | IIf {branch_if_true; branch_if_false; k; _} ->
      let (Item_t (Bool_t, rest)) = sty in
      Script_interpreter_logging.branched_final_stack_type
        [
          Ex_init_stack_ty (rest, branch_if_true);
          Ex_init_stack_ty (rest, branch_if_false);
        ]
      >>?= fun sty' ->
      let k' =
        match sty' with
        | None -> KCons (k, ks)
        | Some sty' ->
            Script_interpreter_logging.instrument_cont logger sty'
            @@ KCons (k, ks)
      in
      let res, stack = stack in
      if accu then (step [@ocaml.tailcall]) g gas branch_if_true k' res stack
      else (step [@ocaml.tailcall]) g gas branch_if_false k' res stack
  | ILoop (_, body, k) ->
      let ks =
        Script_interpreter_logging.instrument_cont logger sty
        @@ KLoop_in (body, KCons (k, ks))
      in
      (next [@ocaml.tailcall]) g gas ks accu stack
  | ILoop_left (_, bl, br) ->
      let ks =
        Script_interpreter_logging.instrument_cont logger sty
        @@ KLoop_in_left (bl, KCons (br, ks))
      in
      (next [@ocaml.tailcall]) g gas ks accu stack
  | IDip (_, b, ty, k) ->
      let (Item_t (_, rest)) = sty in
      Script_interpreter_logging.kinstr_final_stack_type rest b
      >>?= fun rest' ->
      let ign = accu in
      let ks =
        match rest' with
        | None -> KUndip (ign, ty, KCons (k, ks))
        | Some rest' ->
            Script_interpreter_logging.instrument_cont
              logger
              rest'
              (KUndip (ign, ty, KCons (k, ks)))
      in
      let accu, stack = stack in
      (step [@ocaml.tailcall]) g gas b ks accu stack
  | IExec (_, stack_ty, k) ->
      let (Item_t (_, Item_t (Lambda_t (_, ret, _), _))) = sty in
      let sty' = Item_t (ret, Bot_t) in
      let instrument = Script_interpreter_logging.instrument_cont logger sty' in
      iexec instrument (Some logger) g gas stack_ty k ks accu stack
  | IFailwith (kloc, tv) ->
      let {ifailwith} = ifailwith in
      (ifailwith [@ocaml.tailcall]) (Some logger) g gas kloc tv accu
  | IDipn (_, _n, n', b, k) ->
      let accu, stack, restore_prefix = kundip n' accu stack k in
      let dipped_sty = Script_interpreter_logging.dipn_stack_ty n' sty in
      Script_interpreter_logging.kinstr_final_stack_type dipped_sty b
      >>?= fun sty' ->
      let ks =
        match sty' with
        | None -> KCons (restore_prefix, ks)
        | Some sty' ->
            Script_interpreter_logging.instrument_cont logger sty'
            @@ KCons (restore_prefix, ks)
      in
      (step [@ocaml.tailcall]) g gas b ks accu stack
  | IView (_, (View_signature {output_ty; _} as view_signature), stack_ty, k) ->
      let sty' = Item_t (output_ty, Bot_t) in
      let instrument = Script_interpreter_logging.instrument_cont logger sty' in
      (iview [@ocaml.tailcall])
        instrument
        g
        gas
        view_signature
        stack_ty
        k
        ks
        accu
        stack
  | _ -> (step [@ocaml.tailcall]) g gas k ks accu stack
 [@@inline]

and klog :
    type a s r f.
    logger ->
    outdated_context * step_constants ->
    local_gas_counter ->
    (a, s) stack_ty ->
    (a, s, r, f) continuation ->
    (a, s, r, f) continuation ->
    a ->
    s ->
    (r * f * outdated_context * local_gas_counter) tzresult Lwt.t =
 fun logger g gas stack_ty k0 ks accu stack ->
  let ty_for_logging_unsafe = function
    (* This function is only called when logging is enabled.  If
       that's the case, the elaborator must have been called with
       [logging_enabled] option, which ensures that this will not be
       [None]. Realistically, it can happen that the [logging_enabled]
       option was omitted, resulting in a crash here. But this is
       acceptable, because logging is never enabled during block
       validation, so the layer 1 is safe. *)
    | None -> assert false
    | Some ty -> ty
  in
  (match ks with
  | KLog _ -> ()
  | _ -> Script_interpreter_logging.log_control logger ks) ;
  Script_interpreter_logging.log_next_continuation logger stack_ty ks
  >>?= function
  | KCons (ki, k) -> (step [@ocaml.tailcall]) g gas ki k accu stack
  | KLoop_in (ki, k) -> (kloop_in [@ocaml.tailcall]) g gas k0 ki k accu stack
  | KReturn (_, _, _) as k -> (next [@ocaml.tailcall]) g gas k accu stack
  | KLoop_in_left (ki, k) ->
      (kloop_in_left [@ocaml.tailcall]) g gas k0 ki k accu stack
  | KUndip (_, _, _) as k -> (next [@ocaml.tailcall]) g gas k accu stack
  | KIter (body, xty, xs, k) ->
      let instrument =
        Script_interpreter_logging.instrument_cont logger stack_ty
      in
      (kiter [@ocaml.tailcall]) instrument g gas body xty xs k accu stack
  | KList_enter_body (body, xs, ys, ty_opt, len, k) ->
      let instrument =
        let ty = ty_for_logging_unsafe ty_opt in
        let (List_t (vty, _)) = ty in
        let sty = Item_t (vty, stack_ty) in
        Script_interpreter_logging.instrument_cont logger sty
      in
      (klist_enter [@ocaml.tailcall])
        instrument
        g
        gas
        body
        xs
        ys
        ty_opt
        len
        k
        accu
        stack
  | KList_exit_body (body, xs, ys, ty_opt, len, k) ->
      let (Item_t (_, rest)) = stack_ty in
      let instrument = Script_interpreter_logging.instrument_cont logger rest in
      (klist_exit [@ocaml.tailcall])
        instrument
        g
        gas
        body
        xs
        ys
        ty_opt
        len
        k
        accu
        stack
  | KMap_enter_body (body, xs, ys, ty_opt, k) ->
      let instrument =
        let ty = ty_for_logging_unsafe ty_opt in
        let (Map_t (_, vty, _)) = ty in
        let sty = Item_t (vty, stack_ty) in
        Script_interpreter_logging.instrument_cont logger sty
      in
      (kmap_enter [@ocaml.tailcall])
        instrument
        g
        gas
        body
        xs
        ty_opt
        ys
        k
        accu
        stack
  | KMap_exit_body (body, xs, ys, yk, ty_opt, k) ->
      let (Item_t (_, rest)) = stack_ty in
      let instrument = Script_interpreter_logging.instrument_cont logger rest in
      (kmap_exit [@ocaml.tailcall])
        instrument
        g
        gas
        body
        xs
        ty_opt
        ys
        yk
        k
        accu
        stack
  | KMap_head (f, k) -> (next [@ocaml.taillcall]) g gas k (f accu) stack
  | KView_exit (scs, k) ->
      (next [@ocaml.tailcall]) (fst g, scs) gas k accu stack
  | KLog _ as k ->
      (* This case should never happen. *)
      (next [@ocaml.tailcall]) g gas k accu stack
  | KNil as k -> (next [@ocaml.tailcall]) g gas k accu stack
 [@@inline]
(*

   Entrypoints
   ===========

*)

let step_descr ~log_now logger (ctxt, sc) descr accu stack =
  let gas, outdated_ctxt = local_gas_counter_and_outdated_context ctxt in
  (match logger with
  | None -> step (outdated_ctxt, sc) gas descr.kinstr KNil accu stack
  | Some logger ->
      (if log_now then
       let loc = kinstr_location descr.kinstr in
       logger.log_interp descr.kinstr ctxt loc descr.kbef (accu, stack)) ;
      let log =
        ILog
          ( kinstr_location descr.kinstr,
            descr.kbef,
            LogEntry,
            logger,
            descr.kinstr )
      in
      let knil = KLog (KNil, descr.kaft, logger) in
      step (outdated_ctxt, sc) gas log knil accu stack)
  >>=? fun (accu, stack, ctxt, gas) ->
  return (accu, stack, update_context gas ctxt)

let interp logger g lam arg =
  match lam with
  | LamRec (code, _) ->
      step_descr ~log_now:true logger g code arg (lam, (EmptyCell, EmptyCell))
      >|=? fun (ret, (EmptyCell, EmptyCell), ctxt) -> (ret, ctxt)
  | Lam (code, _) ->
      step_descr ~log_now:true logger g code arg (EmptyCell, EmptyCell)
      >|=? fun (ret, (EmptyCell, EmptyCell), ctxt) -> (ret, ctxt)

(*

   High-level functions
   ====================

*)
type execution_arg =
  | Typed_arg :
      Script.location * ('a, _) Script_typed_ir.ty * 'a
      -> execution_arg
  | Untyped_arg : Script.expr -> execution_arg

let lift_execution_arg (type a ac) ctxt ~internal (entrypoint_ty : (a, ac) ty)
    (construct : a -> 'b) arg : ('b * context) tzresult Lwt.t =
  (match arg with
  | Untyped_arg arg ->
      let arg = Micheline.root arg in
      parse_data
        ctxt
        ~elab_conf:Script_ir_translator_config.(make ~legacy:false ())
        ~allow_forged:internal
        entrypoint_ty
        arg
  | Typed_arg (loc, parsed_arg_ty, parsed_arg) ->
      Gas_monad.run
        ctxt
        (Script_ir_translator.ty_eq
           ~error_details:(Informative loc)
           entrypoint_ty
           parsed_arg_ty)
      >>?= fun (res, ctxt) ->
      res >>?= fun Eq ->
      let parsed_arg : a = parsed_arg in
      return (parsed_arg, ctxt))
  >>=? fun (entrypoint_arg, ctxt) -> return (construct entrypoint_arg, ctxt)

type execution_result = {
  script : Script_ir_translator.ex_script;
  code_size : int;
  storage : Script.expr;
  lazy_storage_diff : Lazy_storage.diffs option;
  operations : packed_internal_operation list;
  ticket_diffs : Z.t Ticket_token_map.t;
  ticket_receipt : Ticket_receipt.t;
}

let execute_any_arg logger ctxt mode step_constants ~entrypoint ~internal
    unparsed_script cached_script arg =
  let elab_conf =
    Script_ir_translator_config.make
      ~legacy:true
      ~keep_extra_types_for_interpreter_logging:(Option.is_some logger)
      ()
  in
  (match cached_script with
  | None ->
      parse_script ctxt unparsed_script ~elab_conf ~allow_forged_in_storage:true
  | Some ex_script -> return (ex_script, ctxt))
  >>=? fun ( Ex_script
               (Script
                 {
                   code_size;
                   code;
                   arg_type;
                   storage = old_storage;
                   storage_type;
                   entrypoints;
                   views;
                 }),
             ctxt ) ->
  Gas_monad.run
    ctxt
    (find_entrypoint
       ~error_details:(Informative ())
       arg_type
       entrypoints
       entrypoint)
  >>?= fun (r, ctxt) ->
  let self_contract = Contract.Originated step_constants.self in
  record_trace (Bad_contract_parameter self_contract) r
  >>?= fun (Ex_ty_cstr {ty = entrypoint_ty; construct; original_type_expr = _})
    ->
  trace
    (Bad_contract_parameter self_contract)
    (lift_execution_arg ctxt ~internal entrypoint_ty construct arg)
  >>=? fun (arg, ctxt) ->
  Script_ir_translator.collect_lazy_storage ctxt arg_type arg
  >>?= fun (to_duplicate, ctxt) ->
  Script_ir_translator.collect_lazy_storage ctxt storage_type old_storage
  >>?= fun (to_update, ctxt) ->
  trace
    (Runtime_contract_error step_constants.self)
    (interp logger (ctxt, step_constants) code (arg, old_storage))
  >>=? fun ((ops, new_storage), ctxt) ->
  Script_ir_translator.extract_lazy_storage_diff
    ctxt
    mode
    ~temporary:false
    ~to_duplicate
    ~to_update
    storage_type
    new_storage
  >>=? fun (storage, lazy_storage_diff, ctxt) ->
  trace Cannot_serialize_storage (unparse_data ctxt mode storage_type storage)
  >>=? fun (unparsed_storage, ctxt) ->
  let op_to_couple op = (op.piop, op.lazy_storage_diff) in
  let operations, op_diffs =
    ops.elements |> List.map op_to_couple |> List.split
  in
  let lazy_storage_diff_all =
    match
      List.flatten
        (List.map (Option.value ~default:[]) (op_diffs @ [lazy_storage_diff]))
    with
    | [] -> None
    | diff -> Some diff
  in
  let script =
    Ex_script
      (Script
         {code_size; code; arg_type; storage; storage_type; entrypoints; views})
  in
  Ticket_scanner.type_has_tickets ctxt arg_type
  >>?= fun (arg_type_has_tickets, ctxt) ->
  Ticket_scanner.type_has_tickets ctxt storage_type
  >>?= fun (storage_type_has_tickets, ctxt) ->
  (* Collect the ticket diffs *)
  Ticket_accounting.ticket_diffs
    ctxt
    ~self_contract
    ~arg_type_has_tickets
    ~storage_type_has_tickets
    ~arg
    ~old_storage
    ~new_storage
    ~lazy_storage_diff:(Option.value ~default:[] lazy_storage_diff)
  >>=? fun (ticket_diffs, ticket_receipt, ctxt) ->
  (* We consume gas after the fact in order to not have to instrument
     [script_size] (for efficiency).
     This is safe, as we already pay gas proportional to storage size
     in [unparse_data]. *)
  let size, cost = Script_ir_translator.script_size script in
  Gas.consume ctxt cost >>?= fun ctxt ->
  return
    ( {
        script;
        code_size = size;
        storage = unparsed_storage;
        lazy_storage_diff = lazy_storage_diff_all;
        operations;
        ticket_diffs;
        ticket_receipt;
      },
      ctxt )

let execute_with_typed_parameter ?logger ctxt ~cached_script mode step_constants
    ~script ~entrypoint ~parameter_ty ~location ~parameter ~internal =
  execute_any_arg
    logger
    ctxt
    mode
    step_constants
    ~entrypoint
    ~internal
    script
    cached_script
    (Typed_arg (location, parameter_ty, parameter))

let execute ?logger ctxt ~cached_script mode step_constants ~script ~entrypoint
    ~parameter ~internal =
  execute_any_arg
    logger
    ctxt
    mode
    step_constants
    ~entrypoint
    ~internal
    script
    cached_script
    (Untyped_arg parameter)

(*

    Internals
    =========

*)

(*

   We export the internals definitions for tool that requires
   a white-box view on the interpreter, typically snoop, the
   gas model inference engine.

*)
module Internals = struct
  let next logger g gas sty ks accu stack =
    let ks =
      match logger with None -> ks | Some logger -> KLog (ks, sty, logger)
    in
    next g gas ks accu stack

  let kstep logger ctxt step_constants sty kinstr accu stack =
    let kinstr =
      match logger with
      | None -> kinstr
      | Some logger ->
          ILog (kinstr_location kinstr, sty, LogEntry, logger, kinstr)
    in
    let gas, outdated_ctxt = local_gas_counter_and_outdated_context ctxt in
    step (outdated_ctxt, step_constants) gas kinstr KNil accu stack
    >>=? fun (accu, stack, ctxt, gas) ->
    return (accu, stack, update_context gas ctxt)

  let step (ctxt, step_constants) gas ks accu stack =
    step (ctxt, step_constants) gas ks KNil accu stack

  let step_descr logger ctxt step_constants descr stack =
    step_descr ~log_now:false logger (ctxt, step_constants) descr stack
end