Extend typed lowering to cover JSStrictEqual on differing types.

src/compiler/js-typed-lowering.cc

Index: src/compiler/js-typed-lowering.cc
diff --git a/src/compiler/js-typed-lowering.cc b/src/compiler/js-typed-lowering.cc
index 178a0628f3bb8b567fcd4bcf9821aeb4ebbabb68..8864582590a190c734e9369f485a139842b15301 100644
--- a/src/compiler/js-typed-lowering.cc
+++ b/src/compiler/js-typed-lowering.cc
@@ -459,8 +459,7 @@ Reduction JSTypedLowering::ReduceJSStrictEqual(Node* node, bool invert) {
   if (r.left() == r.right()) {
     // x === x is always true if x != NaN
     if (!r.left_type()->Maybe(Type::NaN())) {
-      return ReplaceEagerly(node, invert ? jsgraph()->FalseConstant()
-                                         : jsgraph()->TrueConstant());
+      return ReplaceEagerly(node, jsgraph()->BooleanConstant(!invert));
     }
   }
   if (r.OneInputIs(Type::Undefined())) {
@@ -489,6 +488,15 @@ Reduction JSTypedLowering::ReduceJSStrictEqual(Node* node, bool invert) {
   if (r.BothInputsAre(Type::Number())) {
     return r.ChangeToPureOperator(simplified()->NumberEqual(), invert);
   }
+  Type* string_or_number = Type::Union(Type::String(), Type::Number(), zone());
+  if (r.OneInputCannotBe(string_or_number)) {
+    // For values with canonical representation (i.e. not string nor number) an
+    // empty type intersection means the values cannot be strictly equal.
+    Type* intersect = Type::Intersect(r.left_type(), r.right_type(), zone());

[rossberg, 2014/11/14 13:41:42]

That's what left_type->Maybe(right_type) is for. ;)

[titzer, 2014/11/14 13:43:24]

I like Maybe, I just want it to be reliable....
/unpopular_opinion_bird 
:(

[Michael Starzinger, 2014/11/14 14:03:06]

Done.

+    if (!intersect->IsInhabited()) {
+      return ReplaceEagerly(node, jsgraph()->BooleanConstant(invert));
+    }
+  }
   // TODO(turbofan): js-typed-lowering of StrictEqual(mixed types)
   return NoChange();
 }