Why doesn't the JVM emit prefetch instructions on Windows x86

As the title states, why doesn't the OpenJDK JVM emit prefetch instruction on Windows x86? See OpenJDK Mercurial @ http://hg.openjdk.java.net/jdk8u/jdk8u/hotspot/file/c49dcaf78a65/src/os_cpu/windows_x86/vm/prefetch_windows_x86.inline.hpp

inline void Prefetch::read (void *loc, intx interval) {}
inline void Prefetch::write(void *loc, intx interval) {}

There are no comments and I've found no other resources besides the source code. I am asking because it does so for Linux x86, see http://hg.openjdk.java.net/jdk8u/jdk8u/hotspot/file/c49dcaf78a65/src/os_cpu/linux_x86/vm/prefetch_linux_x86.inline.hpp

inline void Prefetch::read (void *loc, intx interval) {
#ifdef AMD64
  __asm__ ("prefetcht0 (%0,%1,1)" : : "r" (loc), "r" (interval));
#endif // AMD64
}

inline void Prefetch::write(void *loc, intx interval) {
#ifdef AMD64

  // Do not use the 3dnow prefetchw instruction.  It isn't supported on em64t.
  //  __asm__ ("prefetchw (%0,%1,1)" : : "r" (loc), "r" (interval));
  __asm__ ("prefetcht0 (%0,%1,1)" : : "r" (loc), "r" (interval));

#endif // AMD64
}