Serializer enable/disable flags need thread safety.

src/x64/macro-assembler-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 56 matching lines @@
       reinterpret_cast<Address>(isolate()->heap()->roots_array_start());
   intptr_t delta = other.address() - roots_register_value;
   return delta;
 }
 
 
 Operand MacroAssembler::ExternalOperand(ExternalReference target,
                                         Register scratch) {
   if (root_array_available_ && !Serializer::enabled()) {
     intptr_t delta = RootRegisterDelta(target);
-    if (delta != kInvalidRootRegisterDelta && is_int32(delta)) {
-      Serializer::TooLateToEnableNow();
+    if (delta != kInvalidRootRegisterDelta && is_int32(delta) &&
+        Serializer::TrySetPermanentlyDisabled()) {
       return Operand(kRootRegister, static_cast<int32_t>(delta));
     }
   }
   Move(scratch, target);
   return Operand(scratch, 0);
 }
 
 
 void MacroAssembler::Load(Register destination, ExternalReference source) {
   if (root_array_available_ && !Serializer::enabled()) {
     intptr_t delta = RootRegisterDelta(source);
-    if (delta != kInvalidRootRegisterDelta && is_int32(delta)) {
-      Serializer::TooLateToEnableNow();
+    if (delta != kInvalidRootRegisterDelta && is_int32(delta) &&
+        Serializer::TrySetPermanentlyDisabled()) {
       movp(destination, Operand(kRootRegister, static_cast<int32_t>(delta)));
       return;
     }
   }
   // Safe code.
   if (destination.is(rax)) {
     load_rax(source);
   } else {
     Move(kScratchRegister, source);
     movp(destination, Operand(kScratchRegister, 0));
   }
 }
 
 
 void MacroAssembler::Store(ExternalReference destination, Register source) {
   if (root_array_available_ && !Serializer::enabled()) {
     intptr_t delta = RootRegisterDelta(destination);
-    if (delta != kInvalidRootRegisterDelta && is_int32(delta)) {
-      Serializer::TooLateToEnableNow();
+    if (delta != kInvalidRootRegisterDelta && is_int32(delta) &&
+        Serializer::TrySetPermanentlyDisabled()) {
       movp(Operand(kRootRegister, static_cast<int32_t>(delta)), source);
       return;
     }
   }
   // Safe code.
   if (source.is(rax)) {
     store_rax(destination);
   } else {
     Move(kScratchRegister, destination);
     movp(Operand(kScratchRegister, 0), source);
   }
 }
 
 
 void MacroAssembler::LoadAddress(Register destination,
                                  ExternalReference source) {
   if (root_array_available_ && !Serializer::enabled()) {
     intptr_t delta = RootRegisterDelta(source);
-    if (delta != kInvalidRootRegisterDelta && is_int32(delta)) {
-      Serializer::TooLateToEnableNow();
+    if (delta != kInvalidRootRegisterDelta && is_int32(delta) &&
+        Serializer::TrySetPermanentlyDisabled()) {
       leap(destination, Operand(kRootRegister, static_cast<int32_t>(delta)));
       return;
     }
   }
   // Safe code.
   Move(destination, source);
 }
 
 
 int MacroAssembler::LoadAddressSize(ExternalReference source) {
   if (root_array_available_ && !Serializer::enabled()) {
     // This calculation depends on the internals of LoadAddress.
     // It's correctness is ensured by the asserts in the Call
     // instruction below.
     intptr_t delta = RootRegisterDelta(source);
-    if (delta != kInvalidRootRegisterDelta && is_int32(delta)) {
-      Serializer::TooLateToEnableNow();
+    if (delta != kInvalidRootRegisterDelta && is_int32(delta) &&
+        Serializer::TrySetPermanentlyDisabled()) {
       // Operand is leap(scratch, Operand(kRootRegister, delta));
       // Opcodes : REX.W 8D ModRM Disp8/Disp32  - 4 or 7.
       int size = 4;
       if (!is_int8(static_cast<int32_t>(delta))) {
         size += 3;  // Need full four-byte displacement in lea.
       }
       return size;
     }
   }
   // Size of movp(destination, src);
@@ skipping 4997 matching lines @@
   if (ms.shift() > 0) sarl(rdx, Immediate(ms.shift()));
   movl(rax, dividend);
   shrl(rax, Immediate(31));
   addl(rdx, rax);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64