Fix for 3303 MultithreadedParallelIsolates has a race condition.

src/arm/assembler-arm-inl.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 204 matching lines @@
   Memory::Address_at(pc_) = address;
   if (mode == UPDATE_WRITE_BARRIER && host() != NULL) {
     // TODO(1550) We are passing NULL as a slot because cell can never be on
     // evacuation candidate.
     host()->GetHeap()->incremental_marking()->RecordWrite(
         host(), NULL, cell);
   }
 }
 
 
-static const int kNoCodeAgeSequenceLength = 3;
+static const int kNoCodeAgeSequenceLength = 3 * Assembler::kInstrSize;
 
 
 Handle<Object> RelocInfo::code_age_stub_handle(Assembler* origin) {
   UNREACHABLE();  // This should never be reached on Arm.
   return Handle<Object>();
 }
 
 
 Code* RelocInfo::code_age_stub() {
   ASSERT(rmode_ == RelocInfo::CODE_AGE_SEQUENCE);
   return Code::GetCodeFromTargetAddress(
-      Memory::Address_at(pc_ + Assembler::kInstrSize *
-                         (kNoCodeAgeSequenceLength - 1)));
+      Memory::Address_at(pc_ +
+                         (kNoCodeAgeSequenceLength - Assembler::kInstrSize)));
 }
 
 
 void RelocInfo::set_code_age_stub(Code* stub) {
   ASSERT(rmode_ == RelocInfo::CODE_AGE_SEQUENCE);
-  Memory::Address_at(pc_ + Assembler::kInstrSize *
-                     (kNoCodeAgeSequenceLength - 1)) =
+  Memory::Address_at(pc_ +
+                     (kNoCodeAgeSequenceLength - Assembler::kInstrSize)) =
       stub->instruction_start();
 }
 
 
 Address RelocInfo::call_address() {
   // The 2 instructions offset assumes patched debug break slot or return
   // sequence.
   ASSERT((IsJSReturn(rmode()) && IsPatchedReturnSequence()) ||
          (IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence()));
   return Memory::Address_at(pc_ + 2 * Assembler::kInstrSize);
@@ skipping 280 matching lines @@
     // ldr   ip, [pc, #...]
     // since the instruction accessing this address in the constant pool remains
     // unchanged.
   }
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_ASSEMBLER_ARM_INL_H_