PPC: Mark null and undefined as undetectable, and use it to handle abstract equality comparison in …

src/full-codegen/ppc/full-codegen-ppc.cc

Index: src/full-codegen/ppc/full-codegen-ppc.cc
diff --git a/src/full-codegen/ppc/full-codegen-ppc.cc b/src/full-codegen/ppc/full-codegen-ppc.cc
index 1555344b52aee1dbc88ace133bec18e2fa9ad24e..69e1578d1b49dbc5d24a5476ec4402737fbde37c 100644
--- a/src/full-codegen/ppc/full-codegen-ppc.cc
+++ b/src/full-codegen/ppc/full-codegen-ppc.cc
@@ -514,7 +514,7 @@ void FullCodeGenerator::StackValueContext::Plug(Handle<Object> lit) const {
 void FullCodeGenerator::TestContext::Plug(Handle<Object> lit) const {
   codegen()->PrepareForBailoutBeforeSplit(condition(), true, true_label_,
                                           false_label_);
-  DCHECK(!lit->IsUndetectableObject());  // There are no undetectable literals.
+  DCHECK(lit->IsNull() || lit->IsUndefined() || !lit->IsUndetectableObject());
   if (lit->IsUndefined() || lit->IsNull() || lit->IsFalse()) {
     if (false_label_ != fall_through_) __ b(false_label_);
   } else if (lit->IsTrue() || lit->IsJSObject()) {
@@ -4295,8 +4295,8 @@ void FullCodeGenerator::EmitLiteralCompareTypeof(Expression* expr,
     __ CompareRoot(r3, Heap::kFalseValueRootIndex);
     Split(eq, if_true, if_false, fall_through);
   } else if (String::Equals(check, factory->undefined_string())) {
-    __ CompareRoot(r3, Heap::kUndefinedValueRootIndex);
-    __ beq(if_true);
+    __ CompareRoot(r3, Heap::kNullValueRootIndex);
+    __ beq(if_false);
     __ JumpIfSmi(r3, if_false);
     // Check for undetectable objects => true.
     __ LoadP(r3, FieldMemOperand(r3, HeapObject::kMapOffset));