Runtime: normalize nan when hashing floats

Author: hhugo

compiler/tests-ocaml/lib-hashtbl/hfun_js.expected

@@ -12,9 +12,9 @@
 -0.0		07be548a
 +infty		23ea56fb
 -infty		059f7872
-NaN		23498e72
-NaN#2		23498e72
-NaN#3		23498e72
+NaN		3228858d
+NaN#2		3228858d
+NaN#3		3228858d
 -- Native integers:
 0		07be548a
 -1		3653e015

runtime/js/hash.js

@@ -41,9 +41,25 @@ function caml_hash_mix_final(h) {
 }
 
 //Provides: caml_hash_mix_float
-//Requires: caml_int64_bits_of_float, caml_hash_mix_int64
-function caml_hash_mix_float(h, v0) {
-  return caml_hash_mix_int64(h, caml_int64_bits_of_float(v0));
+//Requires: caml_int64_bits_of_float
+//Requires: caml_hash_mix_int
+//Requires: caml_int64_lo32, caml_int64_hi32
+function caml_hash_mix_float(hash, v0) {
+  var i64 = caml_int64_bits_of_float(v0);
+  var l = caml_int64_lo32(i64);
+  var h = caml_int64_hi32(i64);
+  /* Normalize NaNs */
+  if ((h & 0x7FF00000) == 0x7FF00000 && (l | (h & 0xFFFFF)) != 0) {
+    h = 0x7FF00000;
+    l = 0x00000001;
+  }
+  /* Normalize -0 into +0 */
+  else if (h == (0x80000000 | 0) && l == 0) {
+    h = 1;
+  }
+  hash = caml_hash_mix_int(hash, l);
+  hash = caml_hash_mix_int(hash, h);
+  return hash;
 }
 //Provides: caml_hash_mix_int64
 //Requires: caml_hash_mix_int