In background compilation make a copy of Field in order to freeze its state

runtime/vm/intermediate_language_arm64.cc

Index: runtime/vm/intermediate_language_arm64.cc
diff --git a/runtime/vm/intermediate_language_arm64.cc b/runtime/vm/intermediate_language_arm64.cc
index 3f6d6648ca76c3507ad1d1a6feb63d0f3c65d9c1..79296b39ff373429e50d0a7592f852edc3b1c02e 100644
--- a/runtime/vm/intermediate_language_arm64.cc
+++ b/runtime/vm/intermediate_language_arm64.cc
@@ -21,6 +21,7 @@
 #include "vm/symbols.h"
 
 #define __ compiler->assembler()->
+#define Z (compiler->zone())
 
 namespace dart {
 
@@ -1467,7 +1468,7 @@ void GuardFieldClassInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Label* fail = (deopt != NULL) ? deopt : &fail_label;
 
   if (emit_full_guard) {
-    __ LoadObject(field_reg, Field::ZoneHandle(field().raw()));
+    __ LoadObject(field_reg, Field::ZoneHandle(field().Original()));
 
     FieldAddress field_cid_operand(
         field_reg, Field::guarded_cid_offset(), kUnsignedWord);
@@ -1611,7 +1612,7 @@ void GuardFieldLengthInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
 
     Label ok;
 
-    __ LoadObject(field_reg, Field::ZoneHandle(field().raw()));
+    __ LoadObject(field_reg, Field::ZoneHandle(field().Original()));
 
     __ ldr(offset_reg,
            FieldAddress(field_reg,
@@ -1837,7 +1838,7 @@ void StoreInstanceFieldInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
     Label store_float32x4;
     Label store_float64x2;
 
-    __ LoadObject(temp, Field::ZoneHandle(field().raw()));
+    __ LoadObject(temp, Field::ZoneHandle(Z, field().Original()));
 
     __ LoadFieldFromOffset(temp2, temp, Field::is_nullable_offset(),
                            kUnsignedWord);
@@ -1975,7 +1976,7 @@ void StoreStaticFieldInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   const Register value = locs()->in(0).reg();
   const Register temp = locs()->temp(0).reg();
 
-  __ LoadObject(temp, field());
+  __ LoadObject(temp, Field::ZoneHandle(Z, field().Original()));
   if (this->value()->NeedsStoreBuffer()) {
     __ StoreIntoObjectOffset(
         temp, Field::static_value_offset(), value, CanValueBeSmi());
@@ -2187,7 +2188,7 @@ void LoadFieldInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
     Label load_float32x4;
     Label load_float64x2;
 
-    __ LoadObject(result_reg, Field::ZoneHandle(field()->raw()));
+    __ LoadObject(result_reg, Field::ZoneHandle(field()->Original()));
 
     FieldAddress field_cid_operand(
         result_reg, Field::guarded_cid_offset(), kUnsignedWord);