allocator = MS_SPACE;
allocator = LOS_SPACE;
  public final VM_Address alloc(EXTENT bytes, boolean isScalar, int allocator, 				AllocAdvice advice)    throws VM_PragmaInline {    if (VM.VerifyAssertions) VM._assert(bytes == (bytes & (~(WORD_SIZE-1))));    if (allocator == NURSERY_SPACE && bytes > LOS_SIZE_THRESHOLD)      allocator = MS_SPACE;    VM_Address region;    switch (allocator) {      case  NURSERY_SPACE: region = nursery.alloc(isScalar, bytes); break;      case       MS_SPACE: region = ms.alloc(isScalar, bytes); break;      case IMMORTAL_SPACE: region = immortal.alloc(isScalar, bytes); break;      default:             if (VM.VerifyAssertions) VM.sysFail("No such allocator");	                   region = VM_Address.zero();    }    if (VM.VerifyAssertions) VM._assert(Memory.assertIsZeroed(region, bytes));    return region;  }