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

runtime/vm/assembler_ia32.cc

Index: runtime/vm/assembler_ia32.cc
diff --git a/runtime/vm/assembler_ia32.cc b/runtime/vm/assembler_ia32.cc
index 1a41e68a3c7487c3c95355704acdb1d6b953f630..2759cd2f51716ead718990981121924a90067516 100644
--- a/runtime/vm/assembler_ia32.cc
+++ b/runtime/vm/assembler_ia32.cc
@@ -2163,6 +2163,7 @@ void Assembler::LoadIsolate(Register dst) {
 
 void Assembler::LoadObject(Register dst, const Object& object) {
   ASSERT(!object.IsICData() || ICData::Cast(object).IsOriginal());
+  ASSERT(!object.IsField() || Field::Cast(object).IsOriginal());
   if (object.IsSmi() || object.InVMHeap()) {
     movl(dst, Immediate(reinterpret_cast<int32_t>(object.raw())));
   } else {
@@ -2177,6 +2178,7 @@ void Assembler::LoadObject(Register dst, const Object& object) {
 
 void Assembler::LoadObjectSafely(Register dst, const Object& object) {
   ASSERT(!object.IsICData() || ICData::Cast(object).IsOriginal());
+  ASSERT(!object.IsField() || Field::Cast(object).IsOriginal());
   if (Assembler::IsSafe(object)) {
     LoadObject(dst, object);
   } else {
@@ -2189,6 +2191,7 @@ void Assembler::LoadObjectSafely(Register dst, const Object& object) {
 
 void Assembler::PushObject(const Object& object) {
   ASSERT(!object.IsICData() || ICData::Cast(object).IsOriginal());
+  ASSERT(!object.IsField() || Field::Cast(object).IsOriginal());
   if (object.IsSmi() || object.InVMHeap()) {
     pushl(Immediate(reinterpret_cast<int32_t>(object.raw())));
   } else {
@@ -2203,6 +2206,7 @@ void Assembler::PushObject(const Object& object) {
 
 void Assembler::CompareObject(Register reg, const Object& object) {
   ASSERT(!object.IsICData() || ICData::Cast(object).IsOriginal());
+  ASSERT(!object.IsField() || Field::Cast(object).IsOriginal());
   if (object.IsSmi() || object.InVMHeap()) {
     cmpl(reg, Immediate(reinterpret_cast<int32_t>(object.raw())));
   } else {
@@ -2402,6 +2406,7 @@ void Assembler::StoreIntoObjectNoBarrier(Register object,
 void Assembler::UnverifiedStoreOldObject(const Address& dest,
                                          const Object& value) {
   ASSERT(!value.IsICData() || ICData::Cast(value).IsOriginal());
+  ASSERT(!value.IsField() || Field::Cast(value).IsOriginal());
   ASSERT(value.IsOld());
   ASSERT(!value.InVMHeap());
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
@@ -2416,6 +2421,7 @@ void Assembler::StoreIntoObjectNoBarrier(Register object,
                                          const Object& value,
                                          FieldContent old_content) {
   ASSERT(!value.IsICData() || ICData::Cast(value).IsOriginal());
+  ASSERT(!value.IsField() || Field::Cast(value).IsOriginal());
   VerifyHeapWord(dest, old_content);
   if (value.IsSmi() || value.InVMHeap()) {
     Immediate imm_value(reinterpret_cast<int32_t>(value.raw()));