Implement basic array prefetching hints in Hydrogen.

Implement basic array prefetching hints in Hydrogen.
Insert prefetch instructions for those array element accesses (reads) with the
prefetch hints in IA32 Lithium code generator.

With this CL Kraken reports 60% improvement on audio-dft on Atom, where huge
amount of cache misses were observed before.

Currently the write accesses are not prefetched, just in order to isolate
the individual impacts.

[yuqiang.xian%intel.com, 2012-12-04 08:47:30]

On 2012/12/04 08:12:38, yuqiang.xian%intel.com wrote:

Some files are missing when uploading, so closed this entry. Sorry for the mess.