Support reusable boxes for Float32x4 fields

runtime/vm/flow_graph_compiler_arm.cc

Index: runtime/vm/flow_graph_compiler_arm.cc
diff --git a/runtime/vm/flow_graph_compiler_arm.cc b/runtime/vm/flow_graph_compiler_arm.cc
index 21639f86c8b066d37a5db33791b39eeee2ce6548..e58ae7e5e750d36a150181932ae8c90e7295745a 100644
--- a/runtime/vm/flow_graph_compiler_arm.cc
+++ b/runtime/vm/flow_graph_compiler_arm.cc
@@ -26,6 +26,7 @@ DECLARE_FLAG(int, optimization_counter_threshold);
 DECLARE_FLAG(int, reoptimization_counter_threshold);
 DECLARE_FLAG(bool, enable_type_checks);
 DECLARE_FLAG(bool, eliminate_type_checks);
+DECLARE_FLAG(bool, enable_simd_inline);
 
 
 FlowGraphCompiler::~FlowGraphCompiler() {
@@ -42,6 +43,11 @@ bool FlowGraphCompiler::SupportsUnboxedMints() {
 }
 
 
+bool FlowGraphCompiler::SupportsUnboxedFloat32x4() {
+  return CPUFeatures::neon_supported() && FLAG_enable_simd_inline;
+}
+
+
 bool FlowGraphCompiler::SupportsSinCos() {
   return false;
 }