Eliminate write barrier for global stores at compile time if value stored is a smi.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
===================================================================
--- src/hydrogen-instructions.cc	(revision 9605)
+++ src/hydrogen-instructions.cc	(working copy)
@@ -1746,6 +1746,12 @@
 }
 
 
+HType HChange::CalculateInferredType() {
+  if (from().IsDouble() && to().IsTagged()) return HType::HeapNumber();
+  return type();
+}
+
+
 HType HBitwiseBinaryOperation::CalculateInferredType() {
   return HType::TaggedNumber();
 }
@@ -1801,6 +1807,31 @@
 }
 
 
+HType HStringCharFromCode::CalculateInferredType() {
+  return HType::String();
+}
+
+
+HType HArrayLiteral::CalculateInferredType() {
+  return HType::JSArray();
+}
+
+
+HType HObjectLiteral::CalculateInferredType() {
+  return HType::JSObject();
+}
+
+
+HType HRegExpLiteral::CalculateInferredType() {
+  return HType::JSObject();
+}
+
+
+HType HFunctionLiteral::CalculateInferredType() {
+  return HType::JSObject();
+}
+
+
 HValue* HUnaryMathOperation::EnsureAndPropagateNotMinusZero(
     BitVector* visited) {
   visited->Add(id());