MIPS: Serializer enable/disable flags need thread safety.

src/mips/assembler-mips.cc

Index: src/mips/assembler-mips.cc
diff --git a/src/mips/assembler-mips.cc b/src/mips/assembler-mips.cc
index 29df222f40c78f76b72c9f6be79b1ad89adfa7c4..f3a57f94a50d3c071605a00bfa73a4e658fd885f 100644
--- a/src/mips/assembler-mips.cc
+++ b/src/mips/assembler-mips.cc
@@ -46,6 +46,7 @@ namespace internal {
 #ifdef DEBUG
 bool CpuFeatures::initialized_ = false;
 #endif
+bool CpuFeatures::hint_creating_snapshot_ = false;
 unsigned CpuFeatures::supported_ = 0;
 unsigned CpuFeatures::found_by_runtime_probing_only_ = 0;
 unsigned CpuFeatures::cross_compile_ = 0;
@@ -102,7 +103,23 @@ const char* DoubleRegister::AllocationIndexToString(int index) {
 }
 
 
+void CpuFeatures::SetHintCreatingSnapshot() {
+  hint_creating_snapshot_ = true;
+}
+
+
+void CpuFeatures::ProbeWithoutIsolate() {
+  Probe(hint_creating_snapshot_);
+}
+
+
 void CpuFeatures::Probe() {
+  // The Serializer can only be queried after isolate initialization.
+  Probe(Serializer::enabled());
+}
+
+
+void CpuFeatures::Probe(bool serializer_enabled) {
   unsigned standard_features = (OS::CpuFeaturesImpliedByPlatform() |
                                 CpuFeaturesImpliedByCompiler());
   ASSERT(supported_ == 0 ||
@@ -116,7 +133,7 @@ void CpuFeatures::Probe() {
   // snapshot.
   supported_ |= standard_features;
 
-  if (Serializer::enabled()) {
+  if (serializer_enabled) {
     // No probing for features if we might serialize (generate snapshot).
     return;
   }
@@ -2080,11 +2097,6 @@ void Assembler::RecordRelocInfo(RelocInfo::Mode rmode, intptr_t data) {
   if (!RelocInfo::IsNone(rinfo.rmode())) {
     // Don't record external references unless the heap will be serialized.
     if (rmode == RelocInfo::EXTERNAL_REFERENCE) {
-#ifdef DEBUG
-      if (!Serializer::enabled()) {
-        Serializer::TooLateToEnableNow();
-      }
-#endif
       if (!Serializer::enabled() && !emit_debug_code()) {
         return;
       }