removed unary negation from flambda (#3572)

Author: jvanburen

middle_end/flambda2/from_lambda/lambda_to_flambda_primitives.ml

@@ -539,11 +539,6 @@ let box_vec128 mode (arg : H.expr_primitive) ~current_region : H.expr_primitive
 let unbox_vec128 (arg : H.simple_or_prim) : H.simple_or_prim =
   Prim (Unary (Unbox_number Naked_vec128, arg))
 
-let bint_unary_prim bi mode prim arg1 =
-  box_bint bi mode
-    (Unary
-       (Int_arith (standard_int_of_boxed_integer bi, prim), unbox_bint bi arg1))
-
 let bint_binary_prim bi mode prim arg1 arg2 =
   box_bint bi mode
     (Binary
@@ -1547,7 +1542,10 @@ let convert_lprim ~big_endian (prim : L.primitive) (args : Simple.t list list)
           Printlambda.primitive prim
     in
     [Unary (Duplicate_block { kind }, arg)]
-  | Pnegint, [[arg]] -> [Unary (Int_arith (I.Tagged_immediate, Neg), arg)]
+  | Pnegint, [[arg]] ->
+    let kind = I.Tagged_immediate in
+    let zero = Simple.const_int_of_kind (I.to_kind kind) 0 in
+    [Binary (Int_arith (kind, Sub), Simple zero, arg)]
   | Paddint, [[arg1]; [arg2]] ->
     [Binary (Int_arith (I.Tagged_immediate, Add), arg1, arg2)]
   | Psubint, [[arg1]; [arg2]] ->
@@ -1890,7 +1888,12 @@ let convert_lprim ~big_endian (prim : L.primitive) (args : Simple.t list list)
              unbox_bint source arg ))
         ~current_region ]
   | Pnegbint (bi, mode), [[arg]] ->
-    [bint_unary_prim bi mode Neg arg ~current_region]
+    let size = standard_int_of_boxed_integer bi in
+    [ box_bint bi mode ~current_region
+        (Binary
+           ( Int_arith (size, Sub),
+             Simple (Simple.const_int_of_kind (I.to_kind size) 0),
+             unbox_bint bi arg )) ]
   | Paddbint (bi, mode), [[arg1]; [arg2]] ->
     [bint_binary_prim bi mode Add arg1 arg2 ~current_region]
   | Psubbint (bi, mode), [[arg1]; [arg2]] ->

middle_end/flambda2/parser/fexpr.ml

@@ -270,7 +270,6 @@ type signed_or_unsigned = Flambda_primitive.signed_or_unsigned =
   | Unsigned
 
 type unary_int_arith_op = Flambda_primitive.unary_int_arith_op =
-  | Neg
   | Swap_byte_endianness
 
 type array_kind_for_length = Flambda_primitive.Array_kind_for_length.t =

middle_end/flambda2/parser/flambda_parser.ml

@@ -386,7 +386,6 @@ recursive:
 
 unary_int_arith_op:
   | KWD_BSWAP { Swap_byte_endianness }
-  | TILDEMINUS { Neg }
 
 unop:
   | PRIM_ARRAY_LENGTH; kind = array_kind_for_length { Array_length kind }

middle_end/flambda2/parser/flambda_parser.mly

@@ -557,8 +557,7 @@ let binop ppf binop a b =
       a simple b
 
 let unary_int_arith_op ppf (o : unary_int_arith_op) =
-  Format.pp_print_string ppf
-  @@ match o with Neg -> "~-" | Swap_byte_endianness -> "bswap"
+  Format.pp_print_string ppf @@ match o with Swap_byte_endianness -> "bswap"
 
 let unop ppf u =
   let str s = Format.pp_print_string ppf s in

middle_end/flambda2/parser/print_fexpr.ml

@@ -195,8 +195,13 @@ end = struct
                       "Cannot use [Negation_of_the_other_side] with floats; \
                        use the float version instead"
                 in
+                let zero =
+                  Simple.const_int_of_kind
+                    (K.Standard_int.to_kind standard_int_kind)
+                    0
+                in
                 let prim : P.t =
-                  Unary (Int_arith (standard_int_kind, Neg), other_side)
+                  Binary (Int_arith (standard_int_kind, Sub), zero, other_side)
                 in
                 Some (PR.Set.add (Prim prim) possible_results)
               | Float_negation_of_the_other_side width ->

middle_end/flambda2/simplify/simplify_binary_primitive.ml

@@ -275,9 +275,7 @@ module Unary_int_arith (I : A.Int_number_kind) = struct
     | Known_result ints ->
       assert (not (I.Num.Set.is_empty ints));
       let f =
-        match op with
-        | Neg -> I.Num.neg
-        | Swap_byte_endianness -> I.Num.swap_byte_endianness
+        match op with Swap_byte_endianness -> I.Num.swap_byte_endianness
       in
       let possible_results = I.Num.Set.map f ints in
       let ty = I.these_unboxed possible_results in

middle_end/flambda2/simplify/simplify_unary_primitive.ml

@@ -66,16 +66,12 @@ let unary_int_prim_size kind op =
     ( (kind : Flambda_kind.Standard_int.t),
       (op : Flambda_primitive.unary_int_arith_op) )
   with
-  | Tagged_immediate, Neg -> 1
   | Tagged_immediate, Swap_byte_endianness ->
     (* CR pchambart: size depends a lot of the architecture. If the backend
        handles it, this is a single arith op. *)
     2 + does_not_need_caml_c_call_extcall_size + 1
-  | Naked_immediate, Neg -> 1
   | Naked_immediate, Swap_byte_endianness ->
     does_not_need_caml_c_call_extcall_size + 1
-  | Naked_int64, Neg when arch32 -> does_not_need_caml_c_call_extcall_size + 1
-  | (Naked_int32 | Naked_int64 | Naked_nativeint), Neg -> 1
   | (Naked_int32 | Naked_int64 | Naked_nativeint), Swap_byte_endianness ->
     does_not_need_caml_c_call_extcall_size + 1
 

middle_end/flambda2/terms/code_size.ml

@@ -878,15 +878,11 @@ type num_dimensions = int
 
 let print_num_dimensions ppf d = Format.fprintf ppf "%d" d
 
-type unary_int_arith_op =
-  | Neg
-  | Swap_byte_endianness
+type unary_int_arith_op = Swap_byte_endianness
 
 let print_unary_int_arith_op ppf o =
   let fprintf = Format.fprintf in
-  match o with
-  | Neg -> fprintf ppf "~-"
-  | Swap_byte_endianness -> fprintf ppf "bswap"
+  match o with Swap_byte_endianness -> fprintf ppf "bswap"
 
 type unary_float_arith_op =
   | Abs
@@ -1424,7 +1420,7 @@ let effects_and_coeffects_of_unary_primitive p : Effects_and_coeffects.t =
   | Int_as_pointer alloc_mode ->
     No_effects, coeffects_of_mode alloc_mode, Strict
   | Opaque_identity _ -> Arbitrary_effects, Has_coeffects, Strict
-  | Int_arith (_, (Neg | Swap_byte_endianness))
+  | Int_arith (_, Swap_byte_endianness)
   | Num_conv _ | Boolean_not | Reinterpret_64_bit_word _ ->
     No_effects, No_coeffects, Strict
   | Float_arith (_width, (Abs | Neg)) ->

middle_end/flambda2/terms/flambda_primitive.ml

@@ -339,9 +339,7 @@ type nullary_primitive =
     encoding a 16-bit quantity (described in the least significant 16 bits of
     the immediate after untagging) and exchanges the two halves of the 16-bit
     quantity. The higher-order bits are zeroed. *)
-type unary_int_arith_op =
-  | Neg
-  | Swap_byte_endianness
+type unary_int_arith_op = Swap_byte_endianness
 
 (** Naked float unary arithmetic operations. *)
 type unary_float_arith_op =

middle_end/flambda2/terms/flambda_primitive.mli

@@ -75,7 +75,7 @@ let code size(2)
         my_closure my_region my_ghost_region my_depth
         -> k * k1
         : imm tagged =
-  let Pnegint = %int_arith ~- x in
+  let Pnegint = 0 - x in
   cont k (Pnegint)
 in
 let code size(2)
@@ -202,7 +202,7 @@ let code loopify(never) size(2) newer_version_of(negate_5)
         my_closure my_region my_ghost_region my_depth
         -> k * k1
         : imm tagged =
-  let Pnegint = %int_arith ~- x in
+  let Pnegint = 0 - x in
   cont k (Pnegint)
 in
 let $camlTests15__negate_12 = closure negate_5_1 @negate in

middle_end/flambda2/tests/mlexamples/tests15.flt

@@ -75,7 +75,7 @@ let code size(2)
         my_closure my_region my_ghost_region my_depth
         -> k * k1
         : imm tagged =
-  let Pnegint = %int_arith ~- x in
+  let Pnegint = 0 - x in
   cont k (Pnegint)
 in
 let code size(2)

middle_end/flambda2/tests/mlexamples/tests15_in.fl

@@ -74,7 +74,7 @@ let code loopify(never) size(2) newer_version_of(negate_5)
         my_closure my_region my_ghost_region my_depth
         -> k * k1
         : imm tagged =
-  let Pnegint = %int_arith ~- x in
+  let Pnegint = 0 - x in
   cont k (Pnegint)
 in
 let $camlTests15__negate_12 = closure negate_5_1 @negate in

middle_end/flambda2/tests/mlexamples/tests15_out.fl

@@ -555,18 +555,6 @@ let scalar_type_of_standard_int_or_float :
 
 let unary_int_arith_primitive _env dbg kind op arg =
   match (op : P.unary_int_arith_op) with
-  | Neg -> (
-    match integral_of_standard_int kind with
-    | Tagged src ->
-      C.Scalar_type.Tagged_integer.conjugate ~dbg ~outer:src
-        ~inner:C.Scalar_type.Tagged_integer.immediate
-        ~f:(fun x -> C.negint x dbg)
-        arg
-    | Untagged src ->
-      let bits = C.Scalar_type.Integer.bit_width src in
-      C.Scalar_type.Integer.conjugate arg ~outer:src
-        ~inner:C.Scalar_type.Integer.nativeint ~dbg ~f:(fun arg ->
-          C.neg_int (C.low_bits ~bits arg ~dbg) dbg))
   | Swap_byte_endianness -> (
     match (kind : K.Standard_int.t) with
     | Tagged_immediate ->