The patch changes the order in which L1 dcache and icache are looked up when a 
request comes in. Earlier, if a request came in for instruction fetch, the dcache 
was looked up before the icache, to correctly handle self-modifying code. But, in 
the common case, dcache is going to report a miss and the subsequent icache lookup 
is going to report a hit. Given the invariant - caches under the same controller 
keep track of disjoint sets of cache blocks, we can move the icache lookup before 
the dcache lookup. In case of a hit in the icache, using our invariant, we know 
that the dcache would have reported a miss. In  case of a miss in the icache, we 
know that icache would have missed even if the dcache was looked up before looking 
up the icache. Effectively, we are doing the same thing as before, though in the 
common case, we expect reduction in the number of lookups. This was empirically 
confirmed for MOESI hammer. The ratio lookups to access requests is now about 
1.1 to 1.

All the protocols have been tested using ruby random tester. The parameters 
supplied were l = 10000, n = 4. MOESI hammer was profiled using ruby_fs.py.