CSE of boolean not

Author: chambart

middle_end/flambda/simplify/simplify_unary_primitive.ml

@@ -349,11 +349,20 @@ module Simplify_int_conv_naked_int64 = Make_simplify_int_conv (A.For_int64s)
 module Simplify_int_conv_naked_nativeint =
   Make_simplify_int_conv (A.For_nativeints)
 
-let simplify_boolean_not dacc ~original_term ~arg:_ ~arg_ty ~result_var =
+let simplify_boolean_not dacc ~original_term ~arg ~arg_ty ~result_var =
   let result = Name.var (Var_in_binding_pos.var result_var) in
   let denv = DA.denv dacc in
   let typing_env = DE.typing_env denv in
   let proof = T.prove_equals_tagged_immediates typing_env arg_ty in
+  let dacc =
+    DA.map_denv dacc ~f:(fun denv ->
+      let prim : P.t =
+        Unary (Boolean_not,
+          Simple.var (Var_in_binding_pos.var result_var))
+      in
+      DE.add_cse denv (P.Eligible_for_cse.create_exn prim)
+        ~bound_to:arg)
+  in
   let result_unknown () =
     let ty = T.unknown K.value in
     let env_extension = TEE.one_equation result ty in