Fix Crankshafted CompareNil of constant values

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index ba1de7aa2258a308927c90f937d5d1e6beccd841..f32e0cd2120812eb837594e8132bc5eab1adce02 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -1748,32 +1748,48 @@ void HGraphBuilder::BuildCompareNil(
     HIfContinuation* continuation) {
   IfBuilder if_nil(this, position);
   bool needs_or = false;
-  if (type->Maybe(Type::Null())) {
-    if (needs_or) if_nil.Or();
-    if_nil.If<HCompareObjectEqAndBranch>(value, graph()->GetConstantNull());
-    needs_or = true;
-  }
-  if (type->Maybe(Type::Undefined())) {
-    if (needs_or) if_nil.Or();
-    if_nil.If<HCompareObjectEqAndBranch>(value,
-                                         graph()->GetConstantUndefined());
-    needs_or = true;
-  }
-  if (type->Maybe(Type::Undetectable())) {
-    if (needs_or) if_nil.Or();
-    if_nil.If<HIsUndetectableAndBranch>(value);
+  if (value->IsConstant()) {
+    bool is_null = false;
+    HConstant* constant_value = HConstant::cast(value);
+    if (!constant_value->HasNumberValue()) {
+      Object* constant_object = *(constant_value->handle());

[Jakob Kummerow, 2013/08/14 15:45:20]

nit: let's just keep this handlified, i.e.:
Handle<Object> constant_object = constant_value->handle();

+      is_null = constant_object->IsNull() ||
+          constant_object->IsUndefined() ||
+          constant_object->IsUndetectableObject();
+    }
+    constant_value = is_null
+        ? graph()->GetConstantTrue()
+        : graph()->GetConstantFalse();
+    if_nil.If<HCompareObjectEqAndBranch>(constant_value,
+                                         graph()->GetConstantTrue());
   } else {
-    if_nil.Then();
-    if_nil.Else();
-    if (type->NumClasses() == 1) {
-      BuildCheckHeapObject(value);
-      // For ICs, the map checked below is a sentinel map that gets replaced by
-      // the monomorphic map when the code is used as a template to generate a
-      // new IC. For optimized functions, there is no sentinel map, the map
-      // emitted below is the actual monomorphic map.
-      BuildCheckMap(value, type->Classes().Current());
+    if (type->Maybe(Type::Null())) {
+      if (needs_or) if_nil.Or();
+      if_nil.If<HCompareObjectEqAndBranch>(value, graph()->GetConstantNull());
+      needs_or = true;
+    }
+    if (type->Maybe(Type::Undefined())) {
+      if (needs_or) if_nil.Or();
+      if_nil.If<HCompareObjectEqAndBranch>(value,
+                                           graph()->GetConstantUndefined());
+      needs_or = true;
+    }
+    if (type->Maybe(Type::Undetectable())) {
+      if (needs_or) if_nil.Or();
+      if_nil.If<HIsUndetectableAndBranch>(value);
     } else {
-      if_nil.Deopt("Too many undetectable types");
+      if_nil.Then();
+      if_nil.Else();
+      if (type->NumClasses() == 1) {
+        BuildCheckHeapObject(value);
+        // For ICs, the map checked below is a sentinel map that gets replaced
+        // by the monomorphic map when the code is used as a template to
+        // generate a new IC. For optimized functions, there is no sentinel map,
+        // the map emitted below is the actual monomorphic map.
+        BuildCheckMap(value, type->Classes().Current());
+      } else {
+        if_nil.Deopt("Too many undetectable types");
+      }
     }
   }