Record field initializer stores with simple literals at compile-time.

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 1564 matching lines @@
 
 
 LocationSummary* StoreInstanceFieldInstr::MakeLocationSummary(Isolate* isolate,
                                                               bool opt) const {
   const intptr_t kNumInputs = 2;
   const intptr_t kNumTemps =
       (IsUnboxedStore() && opt) ? 2 :
           ((IsPotentialUnboxedStore()) ? 3 : 0);
   LocationSummary* summary = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps,
-          !field().IsNull() &&
-          ((field().guarded_cid() == kIllegalCid) || is_initialization_)
+          ((IsUnboxedStore() && opt && is_initialization_) ||
+           IsPotentialUnboxedStore())
           ? LocationSummary::kCallOnSlowPath
           : LocationSummary::kNoCall);
 
   summary->set_in(0, Location::RequiresRegister());
   if (IsUnboxedStore() && opt) {
     summary->set_in(1, Location::RequiresFpuRegister());
     summary->set_temp(0, Location::RequiresRegister());
     summary->set_temp(1, Location::RequiresRegister());
   } else if (IsPotentialUnboxedStore()) {
     summary->set_in(1, ShouldEmitStoreBarrier()
@@ skipping 4226 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(ArgumentCount());  // Discard arguments.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64