V8: Add utility functions to check SameValue and SameValueZero.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index e53df91d0ba67f99ba9bb1f422a4b68ff9fed72d..97c8b65a465a7f25746301ded12ee29e239dd110 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -683,13 +683,7 @@ bool Object::SameValue(Object* other) {
   // The object is either a number, a name, an odd-ball,
   // a real JS object, or a Harmony proxy.
   if (IsNumber() && other->IsNumber()) {
-    double this_value = Number();
-    double other_value = other->Number();
-    bool equal = this_value == other_value;
-    // SameValue(NaN, NaN) is true.
-    if (!equal) return std::isnan(this_value) && std::isnan(other_value);
-    // SameValue(0.0, -0.0) is false.
-    return (this_value != 0) || ((1 / this_value) == (1 / other_value));
+    return v8::internal::SameValue(Number(), other->Number());

[adamk, 2015/07/14 18:26:58]

Why the "v8::internal::" prefix here? Does this fail to lookup properly without
it?

[bbudge, 2015/07/14 20:26:24]

Without the prefix, it tries to match to an Object:: overload, which doesn't
exist. I could change the name to same_value but this seems more consistent with
the existing math functions in utils.h.

   }
   if (IsString() && other->IsString()) {
     return String::cast(this)->Equals(String::cast(other));
@@ -704,11 +698,7 @@ bool Object::SameValueZero(Object* other) {
   // The object is either a number, a name, an odd-ball,
   // a real JS object, or a Harmony proxy.
   if (IsNumber() && other->IsNumber()) {
-    double this_value = Number();
-    double other_value = other->Number();
-    // +0 == -0 is true
-    return this_value == other_value
-        || (std::isnan(this_value) && std::isnan(other_value));
+    return v8::internal::SameValueZero(Number(), other->Number());
   }
   if (IsString() && other->IsString()) {
     return String::cast(this)->Equals(String::cast(other));