//===---------------------------------------------------------------------===//
-Instcombine misses several of these cases (see the testcase in the patch):
-http://gcc.gnu.org/ml/gcc-patches/2006-10/msg01519.html
-
-//===---------------------------------------------------------------------===//
-
viterbi speeds up *significantly* if the various "history" related copy loops
are turned into memcpy calls at the source level. We need a "loops to memcpy"
pass.