VM: Fix bug in x64 allocation tracing code.

runtime/vm/assembler_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // NOLINT
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/heap.h"
@@ skipping 3474 matching lines @@
   Address state_address(kNoRegister, 0);
   if (cid < kNumPredefinedCids) {
     ComputeHeapStatsStateAddressForCid(cid, &state_address);
   } else {
     Register temp_reg = TMP;
     const uword class_offset = cid * sizeof(ClassHeapStats);  // NOLINT
     const uword state_offset = ClassHeapStats::state_offset();
     // temp_reg gets address of class table pointer.
     ClassTable* class_table = Isolate::Current()->class_table();
     movq(temp_reg, Immediate(class_table->ClassStatsTableAddress()));
+    movq(temp_reg, Address(temp_reg, 0));
     state_address = Address(temp_reg, class_offset + state_offset);
   }
   testb(state_address, Immediate(ClassHeapStats::TraceAllocationMask()));
   // We are tracing for this class, jump to the trace label which will use
   // the allocation stub.
   j(NOT_ZERO, trace, near_jump);
 }
 
 
 void Assembler::UpdateAllocationStats(intptr_t cid,
@@ skipping 454 matching lines @@
 
 
 const char* Assembler::FpuRegisterName(FpuRegister reg) {
   ASSERT((0 <= reg) && (reg < kNumberOfXmmRegisters));
   return xmm_reg_names[reg];
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64