From 1ad36b13466191ae871aa2ed4649907229491130 Mon Sep 17 00:00:00 2001
From: Carine Morel <carine@tarides.com>
Date: Tue, 25 Jun 2024 18:40:23 +0200
Subject: [PATCH 1/9] Create a multicore-magic-dscheck library.

---
 dune-project                                  |  10 +
 multicore-magic-dscheck.opam                  |  29 ++
 src/dscheck/dune                              |   4 +
 .../multicore_magic_atomic_array_dscheck.ml   |  20 ++
 src/dscheck/multicore_magic_dscheck.ml        |  14 +
 src/dscheck/multicore_magic_dscheck.mli       | 258 ++++++++++++++++++
 src/dscheck/transparent_atomic_dscheck.ml     |   3 +
 7 files changed, 338 insertions(+)
 create mode 100644 multicore-magic-dscheck.opam
 create mode 100644 src/dscheck/dune
 create mode 100644 src/dscheck/multicore_magic_atomic_array_dscheck.ml
 create mode 100644 src/dscheck/multicore_magic_dscheck.ml
 create mode 100644 src/dscheck/multicore_magic_dscheck.mli
 create mode 100644 src/dscheck/transparent_atomic_dscheck.ml

diff --git a/dune-project b/dune-project
index d6d4ea9..2492432 100644
--- a/dune-project
+++ b/dune-project
@@ -41,3 +41,13 @@
    (and
     (>= 2.4.1)
     :with-doc))))
+
+(package
+ (name multicore-magic-dscheck)
+ (synopsis "Low-level multiscore utilities for OCaml")
+ (depends
+  (ocaml
+   (>= 4.12.0))
+  ;; Test dependencies
+  (multicore-magic
+   (= :version))))
diff --git a/multicore-magic-dscheck.opam b/multicore-magic-dscheck.opam
new file mode 100644
index 0000000..3d2c095
--- /dev/null
+++ b/multicore-magic-dscheck.opam
@@ -0,0 +1,29 @@
+# This file is generated by dune, edit dune-project instead
+opam-version: "2.0"
+synopsis: "Low-level multiscore utilities for OCaml"
+maintainer: ["Vesa Karvonen <vesa.a.j.k@gmail.com>"]
+authors: ["Vesa Karvonen <vesa.a.j.k@gmail.com>"]
+license: "ISC"
+homepage: "https://github.com/ocaml-multicore/multicore-magic"
+bug-reports: "https://github.com/ocaml-multicore/multicore-magic/issues"
+depends: [
+  "dune" {>= "3.14"}
+  "ocaml" {>= "4.12.0"}
+  "multicore-magic" {= version}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/ocaml-multicore/multicore-magic.git"
diff --git a/src/dscheck/dune b/src/dscheck/dune
new file mode 100644
index 0000000..af2bb7e
--- /dev/null
+++ b/src/dscheck/dune
@@ -0,0 +1,4 @@
+(library
+ (name multicore_magic_dscheck)
+ (package multicore-magic-dscheck)
+ (libraries multicore-magic dscheck))
diff --git a/src/dscheck/multicore_magic_atomic_array_dscheck.ml b/src/dscheck/multicore_magic_atomic_array_dscheck.ml
new file mode 100644
index 0000000..7389b23
--- /dev/null
+++ b/src/dscheck/multicore_magic_atomic_array_dscheck.ml
@@ -0,0 +1,20 @@
+module Atomic = Dscheck.TracedAtomic
+
+type 'a t = 'a Atomic.t array
+
+let[@inline] at (type a) (xs : a t) i : a Atomic.t =
+  (* ['a t] does not contain [float]s. *)
+  Obj.magic (Array.unsafe_get (Obj.magic xs : a ref array) i)
+
+let[@inline] make n v = Array.init n @@ fun _ -> Atomic.make v
+let[@inline] init n fn = Array.init n @@ fun i -> Atomic.make (fn i)
+let[@inline] of_array xs = init (Array.length xs) (Array.unsafe_get xs)
+
+external length : 'a array -> int = "%array_length"
+
+let[@inline] unsafe_fenceless_set xs i v = Obj.magic (at xs i) := v
+let[@inline] unsafe_fenceless_get xs i = !(Obj.magic (at xs i))
+
+let[@inline] unsafe_compare_and_set xs i b a =
+  Atomic.compare_and_set (at xs i) b a
+
diff --git a/src/dscheck/multicore_magic_dscheck.ml b/src/dscheck/multicore_magic_dscheck.ml
new file mode 100644
index 0000000..c8c2201
--- /dev/null
+++ b/src/dscheck/multicore_magic_dscheck.ml
@@ -0,0 +1,14 @@
+include Multicore_magic
+
+
+let[@inline] fenceless_get (atomic : 'a Atomic.t) =
+  !(Sys.opaque_identity (Obj.magic atomic : 'a ref))
+
+let[@inline] fenceless_set (atomic : 'a Atomic.t) value =
+  (Obj.magic atomic : 'a ref) := value
+
+let[@inline] fence atomic = Atomic.fetch_and_add atomic 0 |> ignore
+
+
+module Transparent_atomic = Transparent_atomic_dscheck
+module Atomic_array = Multicore_magic_atomic_array_dscheck
diff --git a/src/dscheck/multicore_magic_dscheck.mli b/src/dscheck/multicore_magic_dscheck.mli
new file mode 100644
index 0000000..619b09e
--- /dev/null
+++ b/src/dscheck/multicore_magic_dscheck.mli
@@ -0,0 +1,258 @@
+(** This is a library of magic multicore utilities intended for experts for
+    extracting the best possible performance from multicore OCaml.
+
+    Hopefully future releases of multicore OCaml will make this library
+    obsolete! *)
+
+(** {1 Helpers for using padding to avoid false sharing} *)
+
+val copy_as_padded : 'a -> 'a
+(** Depending on the object, either creates a shallow clone of it or returns it
+    as is.  When cloned, the clone will have extra padding words added after the
+    last used word.
+
+    This is designed to help avoid
+    {{:https://en.wikipedia.org/wiki/False_sharing} false sharing}.  False
+    sharing has a negative impact on multicore performance.  Accesses of both
+    atomic and non-atomic locations, whether read-only or read-write, may suffer
+    from false sharing.
+
+    The intended use case for this is to pad all long lived objects that are
+    being accessed highly frequently (read or written).
+
+    Many kinds of objects can be padded, for example:
+
+    {[
+      let padded_atomic = Multicore_magic.copy_as_padded (Atomic.make 101)
+
+      let padded_ref = Multicore_magic.copy_as_padded (ref 42)
+
+      let padded_record = Multicore_magic.copy_as_padded {
+        number = 76;
+        pointer = 1 :: 2 :: 3 :: [];
+      }
+
+      let padded_variant = Multicore_magic.copy_as_padded (Some 1)
+    ]}
+
+    Padding changes the length of an array.  If you need to pad an array, use
+    {!make_padded_array}. *)
+
+val make_padded_array : int -> 'a -> 'a array
+(** Creates a padded array.  The length of the returned array includes padding.
+    Use {!length_of_padded_array} to get the unpadded length. *)
+
+val length_of_padded_array : 'a array -> int
+(** Returns the length of an array created by {!make_padded_array} without the
+    padding.
+
+    {b WARNING}: This is not guaranteed to work with {!copy_as_padded}. *)
+
+val length_of_padded_array_minus_1 : 'a array -> int
+(** Returns the length of an array created by {!make_padded_array} without the
+    padding minus 1.
+
+    {b WARNING}: This is not guaranteed to work with {!copy_as_padded}. *)
+
+(** {1 Missing [Atomic] operations} *)
+
+val fenceless_get : 'a Atomic.t -> 'a
+(** Get a value from the atomic without performing an acquire fence.
+
+    Consider the following prototypical example of a lock-free algorithm:
+
+    {[
+      let rec prototypical_lock_free_algorithm () =
+        let expected = Atomic.get atomic in
+        let desired = (* computed from expected *) in
+        if not (Atomic.compare_and_set atomic expected desired) then
+          (* failure, maybe retry *)
+        else
+          (* success *)
+    ]}
+
+    A potential performance problem with the above example is that it performs
+    two acquire fences.  Both the [Atomic.get] and the [Atomic.compare_and_set]
+    perform an acquire fence.  This may have a negative impact on performance.
+
+    Assuming the first fence is not necessary, we can rewrite the example using
+    {!fenceless_get} as follows:
+
+    {[
+      let rec prototypical_lock_free_algorithm () =
+        let expected = Multicore_magic.fenceless_get atomic in
+        let desired = (* computed from expected *) in
+        if not (Atomic.compare_and_set atomic expected desired) then
+          (* failure, maybe retry *)
+        else
+          (* success *)
+    ]}
+
+    Now only a single acquire fence is performed by [Atomic.compare_and_set] and
+    performance may be improved. *)
+
+val fenceless_set : 'a Atomic.t -> 'a -> unit
+(** Set the value of an atomic without performing a full fence.
+
+    Consider the following example:
+
+    {[
+      let new_atomic = Atomic.make dummy_value in
+      (* prepare data_structure referring to new_atomic *)
+      Atomic.set new_atomic data_structure;
+      (* publish the data_structure: *)
+      Atomic.exchance old_atomic data_structure
+    ]}
+
+    A potential performance problem with the above example is that it performs
+    two full fences.  Both the [Atomic.set] used to initialize the data
+    structure and the [Atomic.exchange] used to publish the data structure
+    perform a full fence.  The same would also apply in cases where
+    [Atomic.compare_and_set] or [Atomic.set] would be used to publish the data
+    structure.  This may have a negative impact on performance.
+
+    Using {!fenceless_set} we can rewrite the example as follows:
+
+    {[
+      let new_atomic = Atomic.make dummy_value in
+      (* prepare data_structure referring to new_atomic *)
+      Multicore_magic.fenceless_set new_atomic data_structure;
+      (* publish the data_structure: *)
+      Atomic.exchance old_atomic data_structure
+    ]}
+
+    Now only a single full fence is performed by [Atomic.exchange] and
+    performance may be improved. *)
+
+val fence : int Atomic.t -> unit
+(** Perform a full acquire-release fence on the given atomic.
+
+    [fence atomic] is equivalent to [ignore (Atomic.fetch_and_add atomic 0)]. *)
+
+(** {1 Fixes and workarounds} *)
+
+module Transparent_atomic : sig
+  (** A replacement for [Stdlib.Atomic] with fixes and performance improvements
+
+      [Stdlib.Atomic.get] is incorrectly subject to CSE optimization in OCaml
+      5.0.0 and 5.1.0.  This can result in code being generated that can produce
+      results that cannot be explained with the OCaml memory model.  It can also
+      sometimes result in code being generated where a manual optimization to
+      avoid writing to memory is defeated by the compiler as the compiler
+      eliminates a (repeated) read access.  This module implements {!get} such
+      that argument to [Stdlib.Atomic.get] is passed through
+      [Sys.opaque_identity], which prevents the compiler from applying the CSE
+      optimization.
+
+      OCaml 5 generates inefficient accesses of ['a Stdlib.Atomic.t array]s
+      assuming that the array might be an array of [float]ing point numbers.
+      That is because the [Stdlib.Atomic.t] type constructor is opaque, which
+      means that the compiler cannot assume that [_ Stdlib.Atomic.t] is not the
+      same as [float].  This module defines {{!t} the type} as [private 'a ref],
+      which allows the compiler to know that it cannot be the same as [float],
+      which allows the compiler to generate more efficient array accesses.  This
+      can both improve performance and reduce size of generated code when using
+      arrays of atomics. *)
+
+  type !'a t
+
+  val make : 'a -> 'a t
+  val make_contended : 'a -> 'a t
+  val get : 'a t -> 'a
+  val fenceless_get : 'a t -> 'a
+  val set : 'a t -> 'a -> unit
+  val fenceless_set : 'a t -> 'a -> unit
+  val exchange : 'a t -> 'a -> 'a
+  val compare_and_set : 'a t -> 'a -> 'a -> bool
+  val fetch_and_add : int t -> int -> int
+  val incr : int t -> unit
+  val decr : int t -> unit
+end
+
+(** {1 Missing functionality} *)
+
+module Atomic_array : sig
+  (** Array of (potentially unboxed) atomic locations.
+
+      Where available, this uses an undocumented operation exported by the OCaml
+      5 runtime,
+      {{:https://github.com/ocaml/ocaml/blob/7a5d882d22cdd32b6319e9be680bd1a3d67377a9/runtime/memory.c#L313-L338}
+      [caml_atomic_cas_field]}, which makes it possible to perform sequentially
+      consistent atomic updates of record fields and array elements.
+
+      Hopefully a future version of OCaml provides more comprehensive and even
+      more efficient support for both sequentially consistent and relaxed atomic
+      operations on records and arrays. *)
+
+  type !'a t
+  (** Represents an array of atomic locations. *)
+
+  val make : int -> 'a -> 'a t
+  (** [make n value] creates a new array of [n] atomic locations having given
+      [value]. *)
+
+  val of_array : 'a array -> 'a t
+  (** [of_array non_atomic_array] create a new array of atomic locations as a
+      copy of the given [non_atomic_array]. *)
+
+  val init : int -> (int -> 'a) -> 'a t
+  (** [init n fn] is equivalent to {{!of_array} [of_array (Array.init n fn)]}. *)
+
+  val length : 'a t -> int
+  (** [length atomic_array] returns the length of the [atomic_array]. *)
+
+  val unsafe_fenceless_get : 'a t -> int -> 'a
+  (** [unsafe_fenceless_get atomic_array index] reads and returns the value at
+      the specified [index] of the [atomic_array].
+
+      ⚠️ The read is {i relaxed} and may be reordered with respect to other reads
+      and writes in program order.
+
+      ⚠️ No bounds checking is performed. *)
+
+  val unsafe_fenceless_set : 'a t -> int -> 'a -> unit
+  (** [unsafe_fenceless_set atomic_array index value] writes the given [value]
+      to the specified [index] of the [atomic_array].
+
+      ⚠️ The write is {i relaxed} and may be reordered with respect to other
+      reads and (non-initializing) writes in program order.
+
+      ⚠️ No bounds checking is performed. *)
+
+  val unsafe_compare_and_set : 'a t -> int -> 'a -> 'a -> bool
+  (** [unsafe_compare_and_set atomic_array index before after] atomically
+      updates the specified [index] of the [atomic_array] to the [after] value
+      in case it had the [before] value and returns a boolean indicating whether
+      that was the case.  This operation is {i sequentially consistent} and may
+      not be reordered with respect to other reads and writes in program order.
+
+      ⚠️ No bounds checking is performed. *)
+end
+
+(** {1 Avoiding contention} *)
+
+val instantaneous_domain_index : unit -> int
+(** [instantaneous_domain_index ()] potentially (re)allocates and returns a
+    non-negative integer "index" for the current domain.  The indices are
+    guaranteed to be unique among the domains that exist at a point in time.
+    Each call of [instantaneous_domain_index ()] may return a different index.
+
+    The intention is that the returned value can be used as an index into a
+    contention avoiding parallelism safe data structure.  For example, a naïve
+    scalable increment of one counter from an array of counters could be done as
+    follows:
+
+    {[
+      let incr counters =
+        (* Assuming length of [counters] is a power of two and larger than
+           the number of domains. *)
+        let mask = Array.length counters - 1 in
+        let index = instantaneous_domain_index () in
+        Atomic.incr counters.(index land mask)
+    ]}
+
+    The implementation ensures that the indices are allocated as densely as
+    possible at any given moment.  This should allow allocating as many counters
+    as needed and essentially eliminate contention.
+
+    On OCaml 4 [instantaneous_domain_index ()] will always return [0]. *)
diff --git a/src/dscheck/transparent_atomic_dscheck.ml b/src/dscheck/transparent_atomic_dscheck.ml
new file mode 100644
index 0000000..a17cc84
--- /dev/null
+++ b/src/dscheck/transparent_atomic_dscheck.ml
@@ -0,0 +1,3 @@
+include Dscheck.TracedAtomic
+let fenceless_get = get
+let fenceless_set = set
\ No newline at end of file

From d9fa5c7f4137dd52796a52a2e3714b1b2064b950 Mon Sep 17 00:00:00 2001
From: Carine Morel <carine@tarides.com>
Date: Mon, 1 Jul 2024 18:48:29 +0200
Subject: [PATCH 2/9] Add a pin-depends to dscheck + formatting.

---
 dune-project                                        | 2 +-
 multicore-magic-dscheck.opam                        | 7 ++++++-
 multicore-magic-dscheck.opam.template               | 5 +++++
 src/dscheck/multicore_magic_atomic_array_dscheck.ml | 1 -
 src/dscheck/multicore_magic_dscheck.ml              | 2 --
 src/dscheck/transparent_atomic_dscheck.ml           | 3 ++-
 6 files changed, 14 insertions(+), 6 deletions(-)
 create mode 100644 multicore-magic-dscheck.opam.template

diff --git a/dune-project b/dune-project
index 2492432..3501c51 100644
--- a/dune-project
+++ b/dune-project
@@ -50,4 +50,4 @@
    (>= 4.12.0))
   ;; Test dependencies
   (multicore-magic
-   (= :version))))
+   (>= 2.2.0))))
diff --git a/multicore-magic-dscheck.opam b/multicore-magic-dscheck.opam
index 3d2c095..06c13fb 100644
--- a/multicore-magic-dscheck.opam
+++ b/multicore-magic-dscheck.opam
@@ -9,7 +9,7 @@ bug-reports: "https://github.com/ocaml-multicore/multicore-magic/issues"
 depends: [
   "dune" {>= "3.14"}
   "ocaml" {>= "4.12.0"}
-  "multicore-magic" {= version}
+  "multicore-magic" {>= "2.2.0"}
   "odoc" {with-doc}
 ]
 build: [
@@ -27,3 +27,8 @@ build: [
   ]
 ]
 dev-repo: "git+https://github.com/ocaml-multicore/multicore-magic.git"
+pin-depends:
+  [
+  "dscheck.~dev"
+  "git+https://github.com/lyrm/dscheck.git#make_contended"
+  ]
\ No newline at end of file
diff --git a/multicore-magic-dscheck.opam.template b/multicore-magic-dscheck.opam.template
new file mode 100644
index 0000000..589e962
--- /dev/null
+++ b/multicore-magic-dscheck.opam.template
@@ -0,0 +1,5 @@
+pin-depends:
+  [
+  "dscheck.~dev"
+  "git+https://github.com/lyrm/dscheck.git#make_contended"
+  ]
\ No newline at end of file
diff --git a/src/dscheck/multicore_magic_atomic_array_dscheck.ml b/src/dscheck/multicore_magic_atomic_array_dscheck.ml
index 7389b23..8a3cdfb 100644
--- a/src/dscheck/multicore_magic_atomic_array_dscheck.ml
+++ b/src/dscheck/multicore_magic_atomic_array_dscheck.ml
@@ -17,4 +17,3 @@ let[@inline] unsafe_fenceless_get xs i = !(Obj.magic (at xs i))
 
 let[@inline] unsafe_compare_and_set xs i b a =
   Atomic.compare_and_set (at xs i) b a
-
diff --git a/src/dscheck/multicore_magic_dscheck.ml b/src/dscheck/multicore_magic_dscheck.ml
index c8c2201..06311c6 100644
--- a/src/dscheck/multicore_magic_dscheck.ml
+++ b/src/dscheck/multicore_magic_dscheck.ml
@@ -1,6 +1,5 @@
 include Multicore_magic
 
-
 let[@inline] fenceless_get (atomic : 'a Atomic.t) =
   !(Sys.opaque_identity (Obj.magic atomic : 'a ref))
 
@@ -9,6 +8,5 @@ let[@inline] fenceless_set (atomic : 'a Atomic.t) value =
 
 let[@inline] fence atomic = Atomic.fetch_and_add atomic 0 |> ignore
 
-
 module Transparent_atomic = Transparent_atomic_dscheck
 module Atomic_array = Multicore_magic_atomic_array_dscheck
diff --git a/src/dscheck/transparent_atomic_dscheck.ml b/src/dscheck/transparent_atomic_dscheck.ml
index a17cc84..d01086d 100644
--- a/src/dscheck/transparent_atomic_dscheck.ml
+++ b/src/dscheck/transparent_atomic_dscheck.ml
@@ -1,3 +1,4 @@
 include Dscheck.TracedAtomic
+
 let fenceless_get = get
-let fenceless_set = set
\ No newline at end of file
+let fenceless_set = set

From 44221971975a7ea797df450957773d4efe19276e Mon Sep 17 00:00:00 2001
From: Carine Morel <carine@tarides.com>
Date: Tue, 2 Jul 2024 12:01:38 +0200
Subject: [PATCH 3/9] WIP : Trying with unwrapped lib and a module named
 multicore_magic. Cycling deps issue.

---
 src/dscheck/dune                              |   6 +-
 src/dscheck/multicore_magic.ml                |  37 +++
 .../multicore_magic_atomic_array_dscheck.ml   |  19 --
 src/dscheck/multicore_magic_dscheck.ml        |  12 -
 src/dscheck/multicore_magic_dscheck.mli       | 258 ------------------
 src/dscheck/transparent_atomic_dscheck.ml     |   4 -
 6 files changed, 41 insertions(+), 295 deletions(-)
 create mode 100644 src/dscheck/multicore_magic.ml
 delete mode 100644 src/dscheck/multicore_magic_atomic_array_dscheck.ml
 delete mode 100644 src/dscheck/multicore_magic_dscheck.ml
 delete mode 100644 src/dscheck/multicore_magic_dscheck.mli
 delete mode 100644 src/dscheck/transparent_atomic_dscheck.ml

diff --git a/src/dscheck/dune b/src/dscheck/dune
index af2bb7e..b649616 100644
--- a/src/dscheck/dune
+++ b/src/dscheck/dune
@@ -1,4 +1,6 @@
 (library
  (name multicore_magic_dscheck)
- (package multicore-magic-dscheck)
- (libraries multicore-magic dscheck))
+ (public_name multicore-magic-dscheck)
+ (wrapped false)
+ (root_module Deps)
+ (libraries multicore-magic dscheck))
\ No newline at end of file
diff --git a/src/dscheck/multicore_magic.ml b/src/dscheck/multicore_magic.ml
new file mode 100644
index 0000000..600a2ae
--- /dev/null
+++ b/src/dscheck/multicore_magic.ml
@@ -0,0 +1,37 @@
+include Deps.Multicore_magic
+module Atomic = Deps.Dscheck.TracedAtomic
+
+module Transparent_atomic = struct
+  include Atomic
+
+  let fenceless_get = get
+  let fenceless_set = set
+end
+
+let[@inline] fenceless_get (atomic : 'a Atomic.t) =
+  !(Sys.opaque_identity (Obj.magic atomic : 'a ref))
+
+let[@inline] fenceless_set (atomic : 'a Atomic.t) value =
+  (Obj.magic atomic : 'a ref) := value
+
+let[@inline] fence atomic = Atomic.fetch_and_add atomic 0 |> ignore
+
+module Atomic_array = struct
+  type 'a t = 'a Atomic.t array
+
+  let[@inline] at (type a) (xs : a t) i : a Atomic.t =
+    (* ['a t] does not contain [float]s. *)
+    Obj.magic (Array.unsafe_get (Obj.magic xs : a ref array) i)
+
+  let[@inline] make n v = Array.init n @@ fun _ -> Atomic.make v
+  let[@inline] init n fn = Array.init n @@ fun i -> Atomic.make (fn i)
+  let[@inline] of_array xs = init (Array.length xs) (Array.unsafe_get xs)
+
+  external length : 'a array -> int = "%array_length"
+
+  let[@inline] unsafe_fenceless_set xs i v = Obj.magic (at xs i) := v
+  let[@inline] unsafe_fenceless_get xs i = !(Obj.magic (at xs i))
+
+  let[@inline] unsafe_compare_and_set xs i b a =
+    Atomic.compare_and_set (at xs i) b a
+end
diff --git a/src/dscheck/multicore_magic_atomic_array_dscheck.ml b/src/dscheck/multicore_magic_atomic_array_dscheck.ml
deleted file mode 100644
index 8a3cdfb..0000000
--- a/src/dscheck/multicore_magic_atomic_array_dscheck.ml
+++ /dev/null
@@ -1,19 +0,0 @@
-module Atomic = Dscheck.TracedAtomic
-
-type 'a t = 'a Atomic.t array
-
-let[@inline] at (type a) (xs : a t) i : a Atomic.t =
-  (* ['a t] does not contain [float]s. *)
-  Obj.magic (Array.unsafe_get (Obj.magic xs : a ref array) i)
-
-let[@inline] make n v = Array.init n @@ fun _ -> Atomic.make v
-let[@inline] init n fn = Array.init n @@ fun i -> Atomic.make (fn i)
-let[@inline] of_array xs = init (Array.length xs) (Array.unsafe_get xs)
-
-external length : 'a array -> int = "%array_length"
-
-let[@inline] unsafe_fenceless_set xs i v = Obj.magic (at xs i) := v
-let[@inline] unsafe_fenceless_get xs i = !(Obj.magic (at xs i))
-
-let[@inline] unsafe_compare_and_set xs i b a =
-  Atomic.compare_and_set (at xs i) b a
diff --git a/src/dscheck/multicore_magic_dscheck.ml b/src/dscheck/multicore_magic_dscheck.ml
deleted file mode 100644
index 06311c6..0000000
--- a/src/dscheck/multicore_magic_dscheck.ml
+++ /dev/null
@@ -1,12 +0,0 @@
-include Multicore_magic
-
-let[@inline] fenceless_get (atomic : 'a Atomic.t) =
-  !(Sys.opaque_identity (Obj.magic atomic : 'a ref))
-
-let[@inline] fenceless_set (atomic : 'a Atomic.t) value =
-  (Obj.magic atomic : 'a ref) := value
-
-let[@inline] fence atomic = Atomic.fetch_and_add atomic 0 |> ignore
-
-module Transparent_atomic = Transparent_atomic_dscheck
-module Atomic_array = Multicore_magic_atomic_array_dscheck
diff --git a/src/dscheck/multicore_magic_dscheck.mli b/src/dscheck/multicore_magic_dscheck.mli
deleted file mode 100644
index 619b09e..0000000
--- a/src/dscheck/multicore_magic_dscheck.mli
+++ /dev/null
@@ -1,258 +0,0 @@
-(** This is a library of magic multicore utilities intended for experts for
-    extracting the best possible performance from multicore OCaml.
-
-    Hopefully future releases of multicore OCaml will make this library
-    obsolete! *)
-
-(** {1 Helpers for using padding to avoid false sharing} *)
-
-val copy_as_padded : 'a -> 'a
-(** Depending on the object, either creates a shallow clone of it or returns it
-    as is.  When cloned, the clone will have extra padding words added after the
-    last used word.
-
-    This is designed to help avoid
-    {{:https://en.wikipedia.org/wiki/False_sharing} false sharing}.  False
-    sharing has a negative impact on multicore performance.  Accesses of both
-    atomic and non-atomic locations, whether read-only or read-write, may suffer
-    from false sharing.
-
-    The intended use case for this is to pad all long lived objects that are
-    being accessed highly frequently (read or written).
-
-    Many kinds of objects can be padded, for example:
-
-    {[
-      let padded_atomic = Multicore_magic.copy_as_padded (Atomic.make 101)
-
-      let padded_ref = Multicore_magic.copy_as_padded (ref 42)
-
-      let padded_record = Multicore_magic.copy_as_padded {
-        number = 76;
-        pointer = 1 :: 2 :: 3 :: [];
-      }
-
-      let padded_variant = Multicore_magic.copy_as_padded (Some 1)
-    ]}
-
-    Padding changes the length of an array.  If you need to pad an array, use
-    {!make_padded_array}. *)
-
-val make_padded_array : int -> 'a -> 'a array
-(** Creates a padded array.  The length of the returned array includes padding.
-    Use {!length_of_padded_array} to get the unpadded length. *)
-
-val length_of_padded_array : 'a array -> int
-(** Returns the length of an array created by {!make_padded_array} without the
-    padding.
-
-    {b WARNING}: This is not guaranteed to work with {!copy_as_padded}. *)
-
-val length_of_padded_array_minus_1 : 'a array -> int
-(** Returns the length of an array created by {!make_padded_array} without the
-    padding minus 1.
-
-    {b WARNING}: This is not guaranteed to work with {!copy_as_padded}. *)
-
-(** {1 Missing [Atomic] operations} *)
-
-val fenceless_get : 'a Atomic.t -> 'a
-(** Get a value from the atomic without performing an acquire fence.
-
-    Consider the following prototypical example of a lock-free algorithm:
-
-    {[
-      let rec prototypical_lock_free_algorithm () =
-        let expected = Atomic.get atomic in
-        let desired = (* computed from expected *) in
-        if not (Atomic.compare_and_set atomic expected desired) then
-          (* failure, maybe retry *)
-        else
-          (* success *)
-    ]}
-
-    A potential performance problem with the above example is that it performs
-    two acquire fences.  Both the [Atomic.get] and the [Atomic.compare_and_set]
-    perform an acquire fence.  This may have a negative impact on performance.
-
-    Assuming the first fence is not necessary, we can rewrite the example using
-    {!fenceless_get} as follows:
-
-    {[
-      let rec prototypical_lock_free_algorithm () =
-        let expected = Multicore_magic.fenceless_get atomic in
-        let desired = (* computed from expected *) in
-        if not (Atomic.compare_and_set atomic expected desired) then
-          (* failure, maybe retry *)
-        else
-          (* success *)
-    ]}
-
-    Now only a single acquire fence is performed by [Atomic.compare_and_set] and
-    performance may be improved. *)
-
-val fenceless_set : 'a Atomic.t -> 'a -> unit
-(** Set the value of an atomic without performing a full fence.
-
-    Consider the following example:
-
-    {[
-      let new_atomic = Atomic.make dummy_value in
-      (* prepare data_structure referring to new_atomic *)
-      Atomic.set new_atomic data_structure;
-      (* publish the data_structure: *)
-      Atomic.exchance old_atomic data_structure
-    ]}
-
-    A potential performance problem with the above example is that it performs
-    two full fences.  Both the [Atomic.set] used to initialize the data
-    structure and the [Atomic.exchange] used to publish the data structure
-    perform a full fence.  The same would also apply in cases where
-    [Atomic.compare_and_set] or [Atomic.set] would be used to publish the data
-    structure.  This may have a negative impact on performance.
-
-    Using {!fenceless_set} we can rewrite the example as follows:
-
-    {[
-      let new_atomic = Atomic.make dummy_value in
-      (* prepare data_structure referring to new_atomic *)
-      Multicore_magic.fenceless_set new_atomic data_structure;
-      (* publish the data_structure: *)
-      Atomic.exchance old_atomic data_structure
-    ]}
-
-    Now only a single full fence is performed by [Atomic.exchange] and
-    performance may be improved. *)
-
-val fence : int Atomic.t -> unit
-(** Perform a full acquire-release fence on the given atomic.
-
-    [fence atomic] is equivalent to [ignore (Atomic.fetch_and_add atomic 0)]. *)
-
-(** {1 Fixes and workarounds} *)
-
-module Transparent_atomic : sig
-  (** A replacement for [Stdlib.Atomic] with fixes and performance improvements
-
-      [Stdlib.Atomic.get] is incorrectly subject to CSE optimization in OCaml
-      5.0.0 and 5.1.0.  This can result in code being generated that can produce
-      results that cannot be explained with the OCaml memory model.  It can also
-      sometimes result in code being generated where a manual optimization to
-      avoid writing to memory is defeated by the compiler as the compiler
-      eliminates a (repeated) read access.  This module implements {!get} such
-      that argument to [Stdlib.Atomic.get] is passed through
-      [Sys.opaque_identity], which prevents the compiler from applying the CSE
-      optimization.
-
-      OCaml 5 generates inefficient accesses of ['a Stdlib.Atomic.t array]s
-      assuming that the array might be an array of [float]ing point numbers.
-      That is because the [Stdlib.Atomic.t] type constructor is opaque, which
-      means that the compiler cannot assume that [_ Stdlib.Atomic.t] is not the
-      same as [float].  This module defines {{!t} the type} as [private 'a ref],
-      which allows the compiler to know that it cannot be the same as [float],
-      which allows the compiler to generate more efficient array accesses.  This
-      can both improve performance and reduce size of generated code when using
-      arrays of atomics. *)
-
-  type !'a t
-
-  val make : 'a -> 'a t
-  val make_contended : 'a -> 'a t
-  val get : 'a t -> 'a
-  val fenceless_get : 'a t -> 'a
-  val set : 'a t -> 'a -> unit
-  val fenceless_set : 'a t -> 'a -> unit
-  val exchange : 'a t -> 'a -> 'a
-  val compare_and_set : 'a t -> 'a -> 'a -> bool
-  val fetch_and_add : int t -> int -> int
-  val incr : int t -> unit
-  val decr : int t -> unit
-end
-
-(** {1 Missing functionality} *)
-
-module Atomic_array : sig
-  (** Array of (potentially unboxed) atomic locations.
-
-      Where available, this uses an undocumented operation exported by the OCaml
-      5 runtime,
-      {{:https://github.com/ocaml/ocaml/blob/7a5d882d22cdd32b6319e9be680bd1a3d67377a9/runtime/memory.c#L313-L338}
-      [caml_atomic_cas_field]}, which makes it possible to perform sequentially
-      consistent atomic updates of record fields and array elements.
-
-      Hopefully a future version of OCaml provides more comprehensive and even
-      more efficient support for both sequentially consistent and relaxed atomic
-      operations on records and arrays. *)
-
-  type !'a t
-  (** Represents an array of atomic locations. *)
-
-  val make : int -> 'a -> 'a t
-  (** [make n value] creates a new array of [n] atomic locations having given
-      [value]. *)
-
-  val of_array : 'a array -> 'a t
-  (** [of_array non_atomic_array] create a new array of atomic locations as a
-      copy of the given [non_atomic_array]. *)
-
-  val init : int -> (int -> 'a) -> 'a t
-  (** [init n fn] is equivalent to {{!of_array} [of_array (Array.init n fn)]}. *)
-
-  val length : 'a t -> int
-  (** [length atomic_array] returns the length of the [atomic_array]. *)
-
-  val unsafe_fenceless_get : 'a t -> int -> 'a
-  (** [unsafe_fenceless_get atomic_array index] reads and returns the value at
-      the specified [index] of the [atomic_array].
-
-      ⚠️ The read is {i relaxed} and may be reordered with respect to other reads
-      and writes in program order.
-
-      ⚠️ No bounds checking is performed. *)
-
-  val unsafe_fenceless_set : 'a t -> int -> 'a -> unit
-  (** [unsafe_fenceless_set atomic_array index value] writes the given [value]
-      to the specified [index] of the [atomic_array].
-
-      ⚠️ The write is {i relaxed} and may be reordered with respect to other
-      reads and (non-initializing) writes in program order.
-
-      ⚠️ No bounds checking is performed. *)
-
-  val unsafe_compare_and_set : 'a t -> int -> 'a -> 'a -> bool
-  (** [unsafe_compare_and_set atomic_array index before after] atomically
-      updates the specified [index] of the [atomic_array] to the [after] value
-      in case it had the [before] value and returns a boolean indicating whether
-      that was the case.  This operation is {i sequentially consistent} and may
-      not be reordered with respect to other reads and writes in program order.
-
-      ⚠️ No bounds checking is performed. *)
-end
-
-(** {1 Avoiding contention} *)
-
-val instantaneous_domain_index : unit -> int
-(** [instantaneous_domain_index ()] potentially (re)allocates and returns a
-    non-negative integer "index" for the current domain.  The indices are
-    guaranteed to be unique among the domains that exist at a point in time.
-    Each call of [instantaneous_domain_index ()] may return a different index.
-
-    The intention is that the returned value can be used as an index into a
-    contention avoiding parallelism safe data structure.  For example, a naïve
-    scalable increment of one counter from an array of counters could be done as
-    follows:
-
-    {[
-      let incr counters =
-        (* Assuming length of [counters] is a power of two and larger than
-           the number of domains. *)
-        let mask = Array.length counters - 1 in
-        let index = instantaneous_domain_index () in
-        Atomic.incr counters.(index land mask)
-    ]}
-
-    The implementation ensures that the indices are allocated as densely as
-    possible at any given moment.  This should allow allocating as many counters
-    as needed and essentially eliminate contention.
-
-    On OCaml 4 [instantaneous_domain_index ()] will always return [0]. *)
diff --git a/src/dscheck/transparent_atomic_dscheck.ml b/src/dscheck/transparent_atomic_dscheck.ml
deleted file mode 100644
index d01086d..0000000
--- a/src/dscheck/transparent_atomic_dscheck.ml
+++ /dev/null
@@ -1,4 +0,0 @@
-include Dscheck.TracedAtomic
-
-let fenceless_get = get
-let fenceless_set = set

From 35b0b1ebc7dafae191c8c8af22afa963772d7ae2 Mon Sep 17 00:00:00 2001
From: Carine Morel <carine@tarides.com>
Date: Tue, 2 Jul 2024 16:42:48 +0200
Subject: [PATCH 4/9] Back to the classic multicore-magic-dscheck way as cyclic
 deps are a real thing apparently.

---
 dune-project                                  |  3 +-
 src/dscheck/dune                              |  4 +-
 ...re_magic.ml => multicore_magic_dscheck.ml} | 11 +++++-
 src/dscheck/multicore_magic_dscheck.mli       | 39 +++++++++++++++++++
 4 files changed, 51 insertions(+), 6 deletions(-)
 rename src/dscheck/{multicore_magic.ml => multicore_magic_dscheck.ml} (80%)
 create mode 100644 src/dscheck/multicore_magic_dscheck.mli

diff --git a/dune-project b/dune-project
index 3501c51..d2d9438 100644
--- a/dune-project
+++ b/dune-project
@@ -44,7 +44,8 @@
 
 (package
  (name multicore-magic-dscheck)
- (synopsis "Low-level multiscore utilities for OCaml")
+ (synopsis
+  "A implementation of multicore-magic API using the atomic module of DScheck to make DScheck tests possible in libraries using multicore-magic.")
  (depends
   (ocaml
    (>= 4.12.0))
diff --git a/src/dscheck/dune b/src/dscheck/dune
index b649616..86455e9 100644
--- a/src/dscheck/dune
+++ b/src/dscheck/dune
@@ -1,6 +1,4 @@
 (library
  (name multicore_magic_dscheck)
  (public_name multicore-magic-dscheck)
- (wrapped false)
- (root_module Deps)
- (libraries multicore-magic dscheck))
\ No newline at end of file
+ (libraries multicore-magic dscheck))
diff --git a/src/dscheck/multicore_magic.ml b/src/dscheck/multicore_magic_dscheck.ml
similarity index 80%
rename from src/dscheck/multicore_magic.ml
rename to src/dscheck/multicore_magic_dscheck.ml
index 600a2ae..b47354a 100644
--- a/src/dscheck/multicore_magic.ml
+++ b/src/dscheck/multicore_magic_dscheck.ml
@@ -1,9 +1,14 @@
-include Deps.Multicore_magic
-module Atomic = Deps.Dscheck.TracedAtomic
+module Atomic = Dscheck.TracedAtomic
+
+let copy_as_padded = Fun.id
+let make_padded_array = Array.make
+let length_of_padded_array = Array.length
+let length_of_padded_array_minus_1 xs = Array.length xs - 1
 
 module Transparent_atomic = struct
   include Atomic
 
+  let make_contended = make
   let fenceless_get = get
   let fenceless_set = set
 end
@@ -35,3 +40,5 @@ module Atomic_array = struct
   let[@inline] unsafe_compare_and_set xs i b a =
     Atomic.compare_and_set (at xs i) b a
 end
+
+let instantaneous_domain_index () = 0
diff --git a/src/dscheck/multicore_magic_dscheck.mli b/src/dscheck/multicore_magic_dscheck.mli
new file mode 100644
index 0000000..faa3163
--- /dev/null
+++ b/src/dscheck/multicore_magic_dscheck.mli
@@ -0,0 +1,39 @@
+module Atomic = Dscheck.TracedAtomic
+
+val copy_as_padded : 'a -> 'a
+val make_padded_array : int -> 'a -> 'a array
+val length_of_padded_array : 'a array -> int
+val length_of_padded_array_minus_1 : 'a array -> int
+val fenceless_get : 'a Atomic.t -> 'a
+val fenceless_set : 'a Atomic.t -> 'a -> unit
+val fence : int Atomic.t -> unit
+
+module Transparent_atomic : sig
+  type !'a t = 'a Atomic.t
+
+  val make : 'a -> 'a t
+  val make_contended : 'a -> 'a t
+  val get : 'a t -> 'a
+  val fenceless_get : 'a t -> 'a
+  val set : 'a t -> 'a -> unit
+  val fenceless_set : 'a t -> 'a -> unit
+  val exchange : 'a t -> 'a -> 'a
+  val compare_and_set : 'a t -> 'a -> 'a -> bool
+  val fetch_and_add : int t -> int -> int
+  val incr : int t -> unit
+  val decr : int t -> unit
+end
+
+module Atomic_array : sig
+  type !'a t
+
+  val make : int -> 'a -> 'a t
+  val of_array : 'a array -> 'a t
+  val init : int -> (int -> 'a) -> 'a t
+  val length : 'a t -> int
+  val unsafe_fenceless_get : 'a t -> int -> 'a
+  val unsafe_fenceless_set : 'a t -> int -> 'a -> unit
+  val unsafe_compare_and_set : 'a t -> int -> 'a -> 'a -> bool
+end
+
+val instantaneous_domain_index : unit -> int

From 49474cd1795d2f105a8608cb7f849b573bd90bf5 Mon Sep 17 00:00:00 2001
From: Carine Morel <carine@tarides.com>
Date: Tue, 2 Jul 2024 17:07:45 +0200
Subject: [PATCH 5/9] Maybe a solution with the -open dune flags ?.

---
 dune-project                                                   | 2 +-
 multicore-magic-dscheck.opam                                   | 3 ++-
 src/dscheck/{multicore_magic_dscheck.ml => multicore_magic.ml} | 0
 .../{multicore_magic_dscheck.mli => multicore_magic.mli}       | 0
 4 files changed, 3 insertions(+), 2 deletions(-)
 rename src/dscheck/{multicore_magic_dscheck.ml => multicore_magic.ml} (100%)
 rename src/dscheck/{multicore_magic_dscheck.mli => multicore_magic.mli} (100%)

diff --git a/dune-project b/dune-project
index d2d9438..651e739 100644
--- a/dune-project
+++ b/dune-project
@@ -45,7 +45,7 @@
 (package
  (name multicore-magic-dscheck)
  (synopsis
-  "A implementation of multicore-magic API using the atomic module of DScheck to make DScheck tests possible in libraries using multicore-magic.")
+  "A implementation of multicore-magic API using the atomic module of DScheck to make DScheck tests possible in libraries using multicore-magic")
  (depends
   (ocaml
    (>= 4.12.0))
diff --git a/multicore-magic-dscheck.opam b/multicore-magic-dscheck.opam
index 06c13fb..c4557e2 100644
--- a/multicore-magic-dscheck.opam
+++ b/multicore-magic-dscheck.opam
@@ -1,6 +1,7 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-synopsis: "Low-level multiscore utilities for OCaml"
+synopsis:
+  "A implementation of multicore-magic API using the atomic module of DScheck to make DScheck tests possible in libraries using multicore-magic."
 maintainer: ["Vesa Karvonen <vesa.a.j.k@gmail.com>"]
 authors: ["Vesa Karvonen <vesa.a.j.k@gmail.com>"]
 license: "ISC"
diff --git a/src/dscheck/multicore_magic_dscheck.ml b/src/dscheck/multicore_magic.ml
similarity index 100%
rename from src/dscheck/multicore_magic_dscheck.ml
rename to src/dscheck/multicore_magic.ml
diff --git a/src/dscheck/multicore_magic_dscheck.mli b/src/dscheck/multicore_magic.mli
similarity index 100%
rename from src/dscheck/multicore_magic_dscheck.mli
rename to src/dscheck/multicore_magic.mli

From 36b8f5c646703b72c1ca9a098254f7e6209241cd Mon Sep 17 00:00:00 2001
From: Carine Morel <carine@tarides.com>
Date: Tue, 2 Jul 2024 17:51:27 +0200
Subject: [PATCH 6/9] dscheck deps.

---
 dune-project                          | 3 ++-
 multicore-magic-dscheck.opam          | 7 ++++---
 multicore-magic-dscheck.opam.template | 4 ++--
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/dune-project b/dune-project
index 651e739..7b64a9a 100644
--- a/dune-project
+++ b/dune-project
@@ -51,4 +51,5 @@
    (>= 4.12.0))
   ;; Test dependencies
   (multicore-magic
-   (>= 2.2.0))))
+   (>= 2.2.0))
+   (dscheck (= dev))))
diff --git a/multicore-magic-dscheck.opam b/multicore-magic-dscheck.opam
index c4557e2..2b2727d 100644
--- a/multicore-magic-dscheck.opam
+++ b/multicore-magic-dscheck.opam
@@ -1,7 +1,7 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
 synopsis:
-  "A implementation of multicore-magic API using the atomic module of DScheck to make DScheck tests possible in libraries using multicore-magic."
+  "A implementation of multicore-magic API using the atomic module of DScheck to make DScheck tests possible in libraries using multicore-magic"
 maintainer: ["Vesa Karvonen <vesa.a.j.k@gmail.com>"]
 authors: ["Vesa Karvonen <vesa.a.j.k@gmail.com>"]
 license: "ISC"
@@ -11,6 +11,7 @@ depends: [
   "dune" {>= "3.14"}
   "ocaml" {>= "4.12.0"}
   "multicore-magic" {>= "2.2.0"}
+  "dscheck" {= "dev"}
   "odoc" {with-doc}
 ]
 build: [
@@ -30,6 +31,6 @@ build: [
 dev-repo: "git+https://github.com/ocaml-multicore/multicore-magic.git"
 pin-depends:
   [
-  "dscheck.~dev"
-  "git+https://github.com/lyrm/dscheck.git#make_contended"
+  "dscheck.dev"
+  "git+https://github.com/lyrm/dscheck.git#d325890d36267dc0d4d76cbd38860ee67cee731e"
   ]
\ No newline at end of file
diff --git a/multicore-magic-dscheck.opam.template b/multicore-magic-dscheck.opam.template
index 589e962..3d6318b 100644
--- a/multicore-magic-dscheck.opam.template
+++ b/multicore-magic-dscheck.opam.template
@@ -1,5 +1,5 @@
 pin-depends:
   [
-  "dscheck.~dev"
-  "git+https://github.com/lyrm/dscheck.git#make_contended"
+  "dscheck.dev"
+  "git+https://github.com/lyrm/dscheck.git#d325890d36267dc0d4d76cbd38860ee67cee731e"
   ]
\ No newline at end of file

From c8c980d66bb98468f2da8a833e2a1b635b711329 Mon Sep 17 00:00:00 2001
From: Carine Morel <carine@tarides.com>
Date: Thu, 4 Jul 2024 10:54:51 +0200
Subject: [PATCH 7/9] Make it work with ocaml < 5.0

---
 dune-project     | 4 +++-
 src/dscheck/dune | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/dune-project b/dune-project
index 7b64a9a..4070162 100644
--- a/dune-project
+++ b/dune-project
@@ -46,10 +46,12 @@
  (name multicore-magic-dscheck)
  (synopsis
   "A implementation of multicore-magic API using the atomic module of DScheck to make DScheck tests possible in libraries using multicore-magic")
+ (allow_empty)
  (depends
   (ocaml
    (>= 4.12.0))
   ;; Test dependencies
   (multicore-magic
    (>= 2.2.0))
-   (dscheck (= dev))))
+  (dscheck
+   (= dev))))
diff --git a/src/dscheck/dune b/src/dscheck/dune
index 86455e9..ca2144d 100644
--- a/src/dscheck/dune
+++ b/src/dscheck/dune
@@ -1,4 +1,6 @@
 (library
  (name multicore_magic_dscheck)
  (public_name multicore-magic-dscheck)
- (libraries multicore-magic dscheck))
+ (libraries multicore-magic dscheck)
+ (enabled_if
+  (>= %{ocaml_version} 5)))

From e7f16b2e0514f58c2083f715750403a9fa842c55 Mon Sep 17 00:00:00 2001
From: Carine Morel <carine@tarides.com>
Date: Thu, 4 Jul 2024 16:20:51 +0200
Subject: [PATCH 8/9] Apply review comments.

---
 dune-project                    |  5 +----
 multicore-magic-dscheck.opam    |  3 +--
 src/dscheck/dune                |  2 +-
 src/dscheck/multicore_magic.ml  | 20 +++++++-------------
 src/dscheck/multicore_magic.mli |  1 +
 5 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/dune-project b/dune-project
index 4070162..66ab1bc 100644
--- a/dune-project
+++ b/dune-project
@@ -50,8 +50,5 @@
  (depends
   (ocaml
    (>= 4.12.0))
-  ;; Test dependencies
-  (multicore-magic
-   (>= 2.2.0))
   (dscheck
-   (= dev))))
+   (>= 0.5.0))))
diff --git a/multicore-magic-dscheck.opam b/multicore-magic-dscheck.opam
index 2b2727d..32bc643 100644
--- a/multicore-magic-dscheck.opam
+++ b/multicore-magic-dscheck.opam
@@ -10,8 +10,7 @@ bug-reports: "https://github.com/ocaml-multicore/multicore-magic/issues"
 depends: [
   "dune" {>= "3.14"}
   "ocaml" {>= "4.12.0"}
-  "multicore-magic" {>= "2.2.0"}
-  "dscheck" {= "dev"}
+  "dscheck" {>= "0.5.0"}
   "odoc" {with-doc}
 ]
 build: [
diff --git a/src/dscheck/dune b/src/dscheck/dune
index ca2144d..b4de21a 100644
--- a/src/dscheck/dune
+++ b/src/dscheck/dune
@@ -1,6 +1,6 @@
 (library
  (name multicore_magic_dscheck)
  (public_name multicore-magic-dscheck)
- (libraries multicore-magic dscheck)
+ (libraries dscheck)
  (enabled_if
   (>= %{ocaml_version} 5)))
diff --git a/src/dscheck/multicore_magic.ml b/src/dscheck/multicore_magic.ml
index b47354a..0af3718 100644
--- a/src/dscheck/multicore_magic.ml
+++ b/src/dscheck/multicore_magic.ml
@@ -1,6 +1,7 @@
 module Atomic = Dscheck.TracedAtomic
 
 let copy_as_padded = Fun.id
+let copy_as ?padded:_ x = x
 let make_padded_array = Array.make
 let length_of_padded_array = Array.length
 let length_of_padded_array_minus_1 xs = Array.length xs - 1
@@ -13,29 +14,22 @@ module Transparent_atomic = struct
   let fenceless_set = set
 end
 
-let[@inline] fenceless_get (atomic : 'a Atomic.t) =
-  !(Sys.opaque_identity (Obj.magic atomic : 'a ref))
-
-let[@inline] fenceless_set (atomic : 'a Atomic.t) value =
-  (Obj.magic atomic : 'a ref) := value
-
+let fenceless_get = Atomic.get
+let fenceless_set = Atomic.set
 let[@inline] fence atomic = Atomic.fetch_and_add atomic 0 |> ignore
 
 module Atomic_array = struct
   type 'a t = 'a Atomic.t array
 
-  let[@inline] at (type a) (xs : a t) i : a Atomic.t =
-    (* ['a t] does not contain [float]s. *)
-    Obj.magic (Array.unsafe_get (Obj.magic xs : a ref array) i)
-
+  let[@inline] at (xs : 'a t) i : 'a Atomic.t = Array.get xs i
   let[@inline] make n v = Array.init n @@ fun _ -> Atomic.make v
   let[@inline] init n fn = Array.init n @@ fun i -> Atomic.make (fn i)
-  let[@inline] of_array xs = init (Array.length xs) (Array.unsafe_get xs)
+  let[@inline] of_array xs = init (Array.length xs) (Array.get xs)
 
   external length : 'a array -> int = "%array_length"
 
-  let[@inline] unsafe_fenceless_set xs i v = Obj.magic (at xs i) := v
-  let[@inline] unsafe_fenceless_get xs i = !(Obj.magic (at xs i))
+  let unsafe_fenceless_set xs i v = Atomic.set xs.(i) v
+  let unsafe_fenceless_get xs i = Atomic.get xs.(i)
 
   let[@inline] unsafe_compare_and_set xs i b a =
     Atomic.compare_and_set (at xs i) b a
diff --git a/src/dscheck/multicore_magic.mli b/src/dscheck/multicore_magic.mli
index faa3163..fc7e9b2 100644
--- a/src/dscheck/multicore_magic.mli
+++ b/src/dscheck/multicore_magic.mli
@@ -1,6 +1,7 @@
 module Atomic = Dscheck.TracedAtomic
 
 val copy_as_padded : 'a -> 'a
+val copy_as : ?padded:bool -> 'a -> 'a
 val make_padded_array : int -> 'a -> 'a array
 val length_of_padded_array : 'a array -> int
 val length_of_padded_array_minus_1 : 'a array -> int

From 1a24f5917bc69261f0a9ecda07a2a217b3db1812 Mon Sep 17 00:00:00 2001
From: Carine Morel <carine@tarides.com>
Date: Tue, 9 Jul 2024 15:00:34 +0200
Subject: [PATCH 9/9] Remove dscheck pin

---
 multicore-magic-dscheck.opam          | 5 -----
 multicore-magic-dscheck.opam.template | 5 -----
 test/dune                             | 1 +
 3 files changed, 1 insertion(+), 10 deletions(-)
 delete mode 100644 multicore-magic-dscheck.opam.template

diff --git a/multicore-magic-dscheck.opam b/multicore-magic-dscheck.opam
index 32bc643..016751d 100644
--- a/multicore-magic-dscheck.opam
+++ b/multicore-magic-dscheck.opam
@@ -28,8 +28,3 @@ build: [
   ]
 ]
 dev-repo: "git+https://github.com/ocaml-multicore/multicore-magic.git"
-pin-depends:
-  [
-  "dscheck.dev"
-  "git+https://github.com/lyrm/dscheck.git#d325890d36267dc0d4d76cbd38860ee67cee731e"
-  ]
\ No newline at end of file
diff --git a/multicore-magic-dscheck.opam.template b/multicore-magic-dscheck.opam.template
deleted file mode 100644
index 3d6318b..0000000
--- a/multicore-magic-dscheck.opam.template
+++ /dev/null
@@ -1,5 +0,0 @@
-pin-depends:
-  [
-  "dscheck.dev"
-  "git+https://github.com/lyrm/dscheck.git#d325890d36267dc0d4d76cbd38860ee67cee731e"
-  ]
\ No newline at end of file
diff --git a/test/dune b/test/dune
index eb86f37..69509fb 100644
--- a/test/dune
+++ b/test/dune
@@ -1,4 +1,5 @@
 (test
  (name Multicore_magic_test)
+ (package multicore-magic)
  (modules Multicore_magic_test)
  (libraries Multicore_magic alcotest domain_shims threads.posix unix))