Use mutable heapnumbers to store doubles in fields.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 3b873699135edefe1b2b36e417b29962e3b2c22b..28b784c33bece55ec87ef4a895f3c91d40a5fbe5 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -2668,29 +2668,21 @@ void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
 
 
 void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
+  int offset = instr->hydrogen()->offset();
   Register object = ToRegister(instr->object());
-  if (!FLAG_track_double_fields) {
-    ASSERT(!instr->hydrogen()->representation().IsDouble());
+  if (FLAG_track_double_fields &&
+      instr->hydrogen()->representation().IsDouble()) {
+    XMMRegister result = ToDoubleRegister(instr->result());
+    __ movsd(result, FieldOperand(object, offset));
+    return;
   }
-  Register temp = instr->hydrogen()->representation().IsDouble()
-      ? ToRegister(instr->temp()) : ToRegister(instr->result());
+
+  Register result = ToRegister(instr->result());
   if (instr->hydrogen()->is_in_object()) {
-    __ movq(temp, FieldOperand(object, instr->hydrogen()->offset()));
+    __ movq(result, FieldOperand(object, offset));
   } else {
-    __ movq(temp, FieldOperand(object, JSObject::kPropertiesOffset));
-    __ movq(temp, FieldOperand(temp, instr->hydrogen()->offset()));
-  }
-
-  if (instr->hydrogen()->representation().IsDouble()) {
-    Label load_from_heap_number, done;
-    XMMRegister result = ToDoubleRegister(instr->result());
-    __ JumpIfNotSmi(temp, &load_from_heap_number);
-    __ SmiToInteger32(temp, temp);
-    __ cvtlsi2sd(result, temp);
-    __ jmp(&done);
-    __ bind(&load_from_heap_number);
-    __ movsd(result, FieldOperand(temp, HeapNumber::kValueOffset));
-    __ bind(&done);
+    __ movq(result, FieldOperand(object, JSObject::kPropertiesOffset));
+    __ movq(result, FieldOperand(result, offset));
   }
 }
 
@@ -3910,6 +3902,8 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
 
   int offset = instr->offset();
 
+  Handle<Map> transition = instr->transition();
+
   if (FLAG_track_fields && representation.IsSmi()) {
     if (instr->value()->IsConstantOperand()) {
       LConstantOperand* operand_value = LConstantOperand::cast(instr->value());
@@ -3920,18 +3914,15 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
       Register value = ToRegister(instr->value());
       __ Integer32ToSmi(value, value);
     }
-  } else if (FLAG_track_double_fields && representation.IsDouble() &&
-             !instr->hydrogen()->value()->type().IsSmi() &&
-             !instr->hydrogen()->value()->type().IsHeapNumber()) {
-    Register value = ToRegister(instr->value());
-    Label do_store;
-    __ JumpIfSmi(value, &do_store);
-    Handle<Map> map(isolate()->factory()->heap_number_map());
-    DoCheckMapCommon(value, map, REQUIRE_EXACT_MAP, instr);
-    __ bind(&do_store);
+  } else if (FLAG_track_double_fields && representation.IsDouble()) {
+    ASSERT(transition.is_null());
+    ASSERT(instr->is_in_object());
+    ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
+    XMMRegister value = ToDoubleRegister(instr->value());
+    __ movsd(FieldOperand(object, offset), value);
+    return;
   }
 
-  Handle<Map> transition = instr->transition();
   if (!transition.is_null()) {
     if (transition->CanBeDeprecated()) {
       transition_maps_.Add(transition, info()->zone());
@@ -3976,6 +3967,7 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
               ToRegister(operand_value));
     } else {
       Handle<Object> handle_value = ToHandle(operand_value);
+      ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
       __ Move(FieldOperand(write_register, offset), handle_value);
     }
   } else {
@@ -5228,7 +5220,8 @@ void LCodeGen::DoObjectLiteral(LObjectLiteral* instr) {
   // Set up the parameters to the stub/runtime call and pick the right
   // runtime function or stub to call.
   int properties_count = instr->hydrogen()->constant_properties_length() / 2;
-  if (instr->hydrogen()->depth() > 1) {
+  if ((FLAG_track_double_fields && instr->hydrogen()->may_store_doubles()) ||
+      instr->hydrogen()->depth() > 1) {
     __ PushHeapObject(literals);
     __ Push(Smi::FromInt(instr->hydrogen()->literal_index()));
     __ Push(constant_properties);