WIP: Poison constants

compilerlibs/Makefile.compilerlibs

@@ -262,6 +262,7 @@ MIDDLE_END_FLAMBDA_TYPES=\
   middle_end/flambda/types/basic/or_bottom.cmo \
   middle_end/flambda/types/basic/string_info.cmo \
   middle_end/flambda/types/basic/or_unknown_or_bottom.cmo \
+  middle_end/flambda/types/basic/or_unknown_or_bottom_or_poison.cmo \
   middle_end/flambda/types/structures/code_age_relation.cmo \
   middle_end/flambda/types/structures/type_structure_intf.cmo \
   middle_end/flambda/types/structures/product_intf.cmo \

flambdatest/mlexamples/unboxing_need_poison.ml

@@ -0,0 +1,17 @@
+type ('a, 'b) t = A of int * 'a | B of 'b
+
+let[@inline] f b y z g =
+  let v =
+    if b then
+      A (42, g y)
+    else
+      B (g z)
+  in
+  match v with
+  | A (_, a) -> a + 2
+  | B c -> c + 2
+
+let[@inline] g x = 12
+
+let test b y z =
+  f b y z g

middle_end/flambda/basic/reg_width_const.ml

@@ -27,6 +27,15 @@ let kind t =
   | Naked_int32 _ -> K.naked_int32
   | Naked_int64 _ -> K.naked_int64
   | Naked_nativeint _ -> K.naked_nativeint
+  | Poison k -> begin
+      match k with
+      | Naked_immediate -> K.naked_immediate
+      | Value -> K.value
+      | Naked_float -> K.naked_float
+      | Naked_int32 -> K.naked_int32
+      | Naked_int64 -> K.naked_int64
+      | Naked_nativeint -> K.naked_nativeint
+    end
 
 let of_descr (descr : Descr.t) =
   match descr with
@@ -36,3 +45,9 @@ let of_descr (descr : Descr.t) =
   | Naked_int32 i -> naked_int32 i
   | Naked_int64 i -> naked_int64 i
   | Naked_nativeint i -> naked_nativeint i
+  | Poison Naked_immediate -> naked_immediate_poison
+  | Poison Value -> value_poison
+  | Poison Naked_float -> naked_float_poison
+  | Poison Naked_int32 -> naked_int32_poison
+  | Poison Naked_int64 -> naked_int64_poison
+  | Poison Naked_nativeint -> naked_nativeint_poison

middle_end/flambda/compilenv_deps/reg_width_things.ml

@@ -26,13 +26,56 @@ let const_flags = 2
 let simple_flags = 3
 
 module Const_data = struct
+  module Kind = struct
+    type t =
+      | Value
+      | Naked_immediate
+      | Naked_float
+      | Naked_int32
+      | Naked_int64
+      | Naked_nativeint
+
+    let compare t1 t2 =
+      match t1, t2 with
+      | Value, Value -> 0
+      | Value, _ -> 1
+      | _, Value -> -1
+      | Naked_immediate, Naked_immediate -> 0
+      | Naked_immediate, _ -> 1
+      | _, Naked_immediate -> -1
+      | Naked_float, Naked_float -> 0
+      | Naked_float, _ -> 1
+      | _, Naked_float -> -1
+      | Naked_int32, Naked_int32 -> 0
+      | Naked_int32, _ -> 1
+      | _, Naked_int32 -> -1
+      | Naked_int64, Naked_int64 -> 0
+      | Naked_int64, _ -> 1
+      | _, Naked_int64 -> -1
+      | Naked_nativeint, Naked_nativeint -> 0
+
+    let equal k1 k2 =
+      match k1, k2 with
+      | Value, Value
+      | Naked_immediate, Naked_immediate
+      | Naked_float, Naked_float
+      | Naked_int32, Naked_int32
+      | Naked_int64, Naked_int64
+      | Naked_nativeint, Naked_nativeint ->
+        true
+      | ( Value | Naked_immediate | Naked_float
+        | Naked_int32 | Naked_int64 | Naked_nativeint ), _ ->
+        false
+  end
+
   type t =
     | Naked_immediate of Target_imm.t
     | Tagged_immediate of Target_imm.t
     | Naked_float of Numbers.Float_by_bit_pattern.t
     | Naked_int32 of Int32.t
     | Naked_int64 of Int64.t
     | Naked_nativeint of Targetint.t
+    | Poison of Kind.t
 
   let flags = const_flags
 
@@ -71,6 +114,24 @@ module Const_data = struct
           (Flambda_colours.naked_number ())
           Targetint.print n
           (Flambda_colours.normal ())
+      | Poison kind ->
+        let colour =
+          match kind with
+          | Value -> Flambda_colours.tagged_immediate
+          | Naked_immediate | Naked_float | Naked_int32
+          | Naked_int64 | Naked_nativeint ->
+            Flambda_colours.naked_number
+        in
+        let poison =
+          if !Clflags.flambda_unicode then
+            "\u{2620}"
+          else
+            "Poison"
+        in
+        Format.fprintf ppf "@<0>%s%s@<0>%s"
+          (colour ())
+          poison
+          (Flambda_colours.normal ())
 
     let output _ _ = Misc.fatal_error "[output] not yet implemented"
 
@@ -88,6 +149,8 @@ module Const_data = struct
         Int64.compare n1 n2
       | Naked_nativeint n1, Naked_nativeint n2 ->
         Targetint.compare n1 n2
+      | Poison k1, Poison k2 ->
+        Kind.compare k1 k2
       | Naked_immediate _, _ -> -1
       | _, Naked_immediate _ -> 1
       | Tagged_immediate _, _ -> -1
@@ -98,6 +161,8 @@ module Const_data = struct
       | _, Naked_int32 _ -> 1
       | Naked_int64 _, _ -> -1
       | _, Naked_int64 _ -> 1
+      | Naked_nativeint _, _ -> -1
+      | _, Naked_nativeint _ -> 1
 
     let equal t1 t2 =
       if t1 == t2 then true
@@ -115,8 +180,11 @@ module Const_data = struct
           Int64.equal n1 n2
         | Naked_nativeint n1, Naked_nativeint n2 ->
           Targetint.equal n1 n2
+        | Poison k1, Poison k2 ->
+          Kind.equal k1 k2
         | (Naked_immediate _ | Tagged_immediate _ | Naked_float _
-            | Naked_int32 _ | Naked_int64 _ | Naked_nativeint _), _ -> false
+            | Naked_int32 _ | Naked_int64 _ | Naked_nativeint _
+            | Poison _ ), _ -> false
 
     let hash t =
       match t with
@@ -126,6 +194,7 @@ module Const_data = struct
       | Naked_int32 n -> Hashtbl.hash n
       | Naked_int64 n -> Hashtbl.hash n
       | Naked_nativeint n -> Targetint.hash n
+      | Poison k -> Hashtbl.hash k
   end)
 end
 
@@ -288,6 +357,13 @@ module Const = struct
   let const_one = tagged_immediate Target_imm.one
   let const_unit = const_zero
 
+  let naked_immediate_poison = create (Poison Naked_immediate)
+  let value_poison = create (Poison Value)
+  let naked_float_poison = create (Poison Naked_float)
+  let naked_int32_poison = create (Poison Naked_int32)
+  let naked_int64_poison = create (Poison Naked_int64)
+  let naked_nativeint_poison = create (Poison Naked_nativeint)
+
   let descr t = find_data t
 
   module T0 = struct

middle_end/flambda/compilenv_deps/reg_width_things.mli

@@ -52,14 +52,32 @@ module Const : sig
   val naked_int64 : Int64.t -> t
   val naked_nativeint : Targetint.t -> t
 
+  val naked_immediate_poison : t
+  val value_poison : t
+  val naked_float_poison : t
+  val naked_int32_poison : t
+  val naked_int64_poison : t
+  val naked_nativeint_poison : t
+
   module Descr : sig
-    type t = private
-      | Naked_immediate of Target_imm.t
-      | Tagged_immediate of Target_imm.t
-      | Naked_float of Numbers.Float_by_bit_pattern.t
-      | Naked_int32 of Int32.t
-      | Naked_int64 of Int64.t
-      | Naked_nativeint of Targetint.t
+    module Kind : sig
+      type t = private
+        | Value
+        | Naked_immediate
+        | Naked_float
+        | Naked_int32
+        | Naked_int64
+        | Naked_nativeint
+    end
+
+  type t = private
+    | Naked_immediate of Target_imm.t
+    | Tagged_immediate of Target_imm.t
+    | Naked_float of Numbers.Float_by_bit_pattern.t
+    | Naked_int32 of Int32.t
+    | Naked_int64 of Int64.t
+    | Naked_nativeint of Targetint.t
+    | Poison of Kind.t
 
     include Identifiable.S with type t := t
   end

middle_end/flambda/parser/flambda_to_fexpr.ml

@@ -272,6 +272,13 @@ let const c : Fexpr.const =
     Naked_int64 i
   | Naked_nativeint i ->
     Naked_nativeint (i |> Targetint.to_int64)
+  | Poison Naked_immediate
+  | Poison Value
+  | Poison Naked_float
+  | Poison Naked_int32
+  | Poison Naked_int64
+  | Poison Naked_nativeint ->
+    Misc.fatal_errorf "TODO: Poison constants"
 
 let simple env s =
   Simple.pattern_match s

middle_end/flambda/simplify/simplify_named.ml

@@ -71,6 +71,7 @@ let record_any_symbol_projection dacc (defining_expr : Simplified_named.t)
         Simple.pattern_match index
           ~const:(fun const ->
             match Reg_width_const.descr const with
+            | Poison Value -> None
             | Tagged_immediate imm ->
               Simple.pattern_match' block
                 ~const:(fun _ -> None)
@@ -80,7 +81,9 @@ let record_any_symbol_projection dacc (defining_expr : Simplified_named.t)
                     (SP.Projection.block_load ~index)))
                 ~var:(fun _ -> None)
             | Naked_immediate _ | Naked_float _
-            | Naked_int32 _ | Naked_int64 _ | Naked_nativeint _ ->
+            | Naked_int32 _ | Naked_int64 _ | Naked_nativeint _
+            | Poison ( Naked_immediate | Naked_float | Naked_int32
+              | Naked_int64 | Naked_nativeint )->
               Misc.fatal_errorf "Kind error for [Block_load] index:@ \
                   %a@ =@ %a"
                 Bindable_let_bound.print bindable_let_bound

middle_end/flambda/simplify/simplify_static_const.ml

@@ -42,8 +42,13 @@ let simplify_field_of_block dacc (field : Field_of_block.t) =
         ~const:(fun const ->
           match Reg_width_const.descr const with
           | Tagged_immediate imm -> Field_of_block.Tagged_immediate imm, ty
+          | Poison Value ->
+            (* CR pchambart: This should be "invalid" and propagate up *)
+            field, T.bottom K.value
           | Naked_immediate _ | Naked_float _ | Naked_int32 _
-              | Naked_int64 _ | Naked_nativeint _ ->
+              | Naked_int64 _ | Naked_nativeint _
+              | Poison ( Naked_immediate | Naked_float | Naked_int32
+                | Naked_int64 | Naked_nativeint ) ->
             (* CR mshinwell: This should be "invalid" and propagate up *)
             field, ty)
 

middle_end/flambda/simplify/simplify_switch_expr.ml

@@ -99,6 +99,7 @@ let rebuild_switch ~simplify_let dacc ~arms ~scrutinee ~scrutinee_ty uacc
                     normal_case ~identity_arms ~not_arms
                   else
                     normal_case ~identity_arms ~not_arms
+                | Poison _
                 | Naked_immediate _ | Naked_float _ | Naked_int32 _
                 | Naked_int64 _ | Naked_nativeint _ ->
                   normal_case ~identity_arms ~not_arms

middle_end/flambda/to_cmm/un_cps.ml

@@ -77,13 +77,22 @@ let const _env cst =
   match Reg_width_const.descr cst with
   | Naked_immediate i ->
     C.targetint (targetint_of_imm i)
+  | Poison Naked_immediate ->
+    C.targetint (targetint_of_imm Target_imm.zero)
   | Tagged_immediate i ->
     C.targetint (tag_targetint (targetint_of_imm i))
+  | Poison Value ->
+    C.targetint (tag_targetint (targetint_of_imm Target_imm.zero))
   | Naked_float f ->
     C.float (Numbers.Float_by_bit_pattern.to_float f)
+  | Poison Naked_float ->
+    C.float 0.
   | Naked_int32 i -> C.int32 i
+  | Poison Naked_int32 -> C.int32 0l
   | Naked_int64 i -> C.int64 i
+  | Poison Naked_int64 -> C.int64 0L
   | Naked_nativeint t -> C.targetint t
+  | Poison Naked_nativeint -> C.targetint Targetint.zero
 
 let default_of_kind (k : Flambda_kind.t) =
   match k with

middle_end/flambda/to_cmm/un_cps_static.ml

@@ -57,17 +57,31 @@ let const_static _env cst =
   match Reg_width_const.descr cst with
   | Naked_immediate i ->
       [C.cint (nativeint_of_targetint (targetint_of_imm i))]
+  | Poison Naked_immediate ->
+      (* CR pchambart: Should we use something more noticeable than 0 ? *)
+      [C.cint 0n]
   | Tagged_immediate i ->
       [C.cint (nativeint_of_targetint (tag_targetint (targetint_of_imm i)))]
+  | Poison Value ->
+      [C.cint 1n]
   | Naked_float f ->
       [C.cfloat (Numbers.Float_by_bit_pattern.to_float f)]
+  | Poison Naked_float ->
+      [C.cfloat 0.]
   | Naked_int32 i ->
       [C.cint (Nativeint.of_int32 i)]
+  | Poison Naked_int32 ->
+      [C.cint 0n]
   | Naked_int64 i ->
       if C.arch32 then todo() (* split int64 on 32-bit archs *)
       else [C.cint (Int64.to_nativeint i)]
+  | Poison Naked_int64 ->
+      if C.arch32 then todo() (* split int64 on 32-bit archs *)
+      else [C.cint 0n]
   | Naked_nativeint t ->
       [C.cint (nativeint_of_targetint t)]
+  | Poison Naked_nativeint ->
+      [C.cint 0n]
 
 let simple_static env s =
   Simple.pattern_match s