| Index: runtime/vm/atomic_win.h | 
| diff --git a/runtime/vm/atomic_win.h b/runtime/vm/atomic_win.h | 
| index 38ec10a1f8996841078d0dec585ed38f8fe84601..2f8ee20b5817e77e7869ba3dccfa857e21bdc441 100644 | 
| --- a/runtime/vm/atomic_win.h | 
| +++ b/runtime/vm/atomic_win.h | 
| @@ -28,6 +28,19 @@ inline uintptr_t AtomicOperations::FetchAndIncrement(uintptr_t* p) { | 
| } | 
|  | 
|  | 
| +inline intptr_t AtomicOperations::FetchAndIncrement(intptr_t* p) { | 
| +#if defined(HOST_ARCH_X64) | 
| +  return static_cast<intptr_t>( | 
| +      InterlockedIncrement64(reinterpret_cast<LONGLONG*>(p))) - 1; | 
| +#elif defined(HOST_ARCH_IA32) | 
| +  return static_cast<intptr_t>( | 
| +      InterlockedIncrement(reinterpret_cast<LONG*>(p))) - 1; | 
| +#else | 
| +#error Unsupported host architecture. | 
| +#endif | 
| +} | 
| + | 
| + | 
| inline void AtomicOperations::IncrementBy(intptr_t* p, intptr_t value) { | 
| #if defined(HOST_ARCH_X64) | 
| InterlockedExchangeAdd64(reinterpret_cast<LONGLONG*>(p), | 
| @@ -64,6 +77,19 @@ inline uintptr_t AtomicOperations::FetchAndDecrement(uintptr_t* p) { | 
| } | 
|  | 
|  | 
| +inline intptr_t AtomicOperations::FetchAndDecrement(intptr_t* p) { | 
| +#if defined(HOST_ARCH_X64) | 
| +  return static_cast<intptr_t>( | 
| +      InterlockedDecrement64(reinterpret_cast<LONGLONG*>(p))) + 1; | 
| +#elif defined(HOST_ARCH_IA32) | 
| +  return static_cast<intptr_t>( | 
| +      InterlockedDecrement(reinterpret_cast<LONG*>(p))) + 1; | 
| +#else | 
| +#error Unsupported host architecture. | 
| +#endif | 
| +} | 
| + | 
| + | 
| inline void AtomicOperations::DecrementBy(intptr_t* p, intptr_t value) { | 
| #if defined(HOST_ARCH_X64) | 
| InterlockedExchangeAdd64(reinterpret_cast<LONGLONG*>(p), | 
|  |