DBC: Enables unboxed doubles

runtime/vm/flow_graph_compiler_dbc.cc

 // Copyright (c) 2016, 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_DBC.
 #if defined(TARGET_ARCH_DBC)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
@@ skipping 26 matching lines @@
 FlowGraphCompiler::~FlowGraphCompiler() {
   // BlockInfos are zone-allocated, so their destructors are not called.
   // Verify the labels explicitly here.
   for (int i = 0; i < block_info_.length(); ++i) {
     ASSERT(!block_info_[i]->jump_label()->IsLinked());
   }
 }
 
 
 bool FlowGraphCompiler::SupportsUnboxedDoubles() {
+#if defined(ARCH_IS_64_BIT)
+  return true;
+#else
+  // We use 64-bit wide stack slots to unbox doubles.
   return false;
+#endif
 }
 
 
 bool FlowGraphCompiler::SupportsUnboxedMints() {
   return false;
 }
 
 
 bool FlowGraphCompiler::SupportsUnboxedSimd128() {
   return false;
@@ skipping 457 matching lines @@
 void ParallelMoveResolver::RestoreFpuScratch(FpuRegister reg) {
   UNIMPLEMENTED();
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_DBC