Make NaNs quiet when converting to/from bits

V8 can turn signalling NaNs into quite NaNs, so it is more consistent
to hide the difference.

Author: vouillon

compiler/lib/eval.ml

@@ -139,6 +139,8 @@ let nativeint_shiftop (l : constant list) (f : int32 -> int -> int32) : constant
   | [ NativeInt i; Int j ] -> Some (NativeInt (f i (Targetint.to_int_exn j)))
   | _ -> None
 
+let quiet_nan n = Int64.logor n 0x00_08_00_00_00_00_00_00L
+
 let eval_prim ~target x =
   match x with
   | Not, [ Int i ] -> bool (Targetint.is_zero i)
@@ -236,7 +238,9 @@ let eval_prim ~target x =
              | `JavaScript ->
                  let f = Int32.float_of_bits i in
                  (not (Float.is_nan f))
-                 || Int64.equal (Int64.bits_of_float f) (Int64.bits_of_float nan)
+                 || Int64.equal
+                      (quiet_nan (Int64.bits_of_float f))
+                      (Int64.bits_of_float nan)
              | `Wasm -> true -> Some (float (Int32.float_of_bits i))
       | "caml_int32_of_float", [ Float f ] ->
           int32 (Int32.of_float (Int64.float_of_bits f))
@@ -269,7 +273,9 @@ let eval_prim ~target x =
              | `JavaScript ->
                  let f = Int32.float_of_bits i in
                  (not (Float.is_nan f))
-                 || Int64.equal (Int64.bits_of_float f) (Int64.bits_of_float nan)
+                 || Int64.equal
+                      (quiet_nan (Int64.bits_of_float f))
+                      (Int64.bits_of_float nan)
              | `Wasm -> true -> Some (float (Int32.float_of_bits i))
       | "caml_nativeint_of_float", [ Float f ] ->
           nativeint (Int32.of_float (Int64.float_of_bits f))
@@ -299,7 +305,7 @@ let eval_prim ~target x =
         when match target with
              | `JavaScript ->
                  (not (Float.is_nan (Int64.float_of_bits i)))
-                 || Int64.equal i (Int64.bits_of_float nan)
+                 || Int64.equal (quiet_nan i) (Int64.bits_of_float nan)
              | `Wasm -> true -> Some (Float i)
       | "caml_int64_of_float", [ Float f ] ->
           int64 (Int64.of_float (Int64.float_of_bits f))

compiler/tests-full/stdlib.cma.expected.js

@@ -8028,7 +8028,6 @@
     caml_floatarray_make = runtime.caml_floatarray_make,
     caml_floatarray_sub = runtime.caml_floatarray_sub,
     caml_hash = runtime.caml_hash,
-    caml_int64_create_lo_mi_hi = runtime.caml_int64_create_lo_mi_hi,
     caml_maybe_attach_backtrace = runtime.caml_maybe_attach_backtrace,
     caml_nextafter_float = runtime.caml_nextafter_float,
     caml_signbit_float = runtime.caml_signbit_float,
@@ -8051,10 +8050,7 @@
     Stdlib = global_data.Stdlib,
     infinity = Stdlib[22],
     neg_infinity = Stdlib[23],
-    nan = Stdlib[24],
-    signaling_nan =
-       /*<<float.ml:38:20>>*/ runtime.caml_int64_float_of_bits
-       (caml_int64_create_lo_mi_hi(1, 0, 32752));
+    nan = Stdlib[24];
    function is_finite(x){
      /*<<float.ml:39:33>>*/ return x - x === 0. ? 1 : 0;
     /*<<float.ml:39:38>>*/ }
@@ -8987,7 +8983,7 @@
        infinity,
        neg_infinity,
        nan,
-       signaling_nan,
+       NaN,
        nan,
        3.141592653589793,
        max_float,