ARM patterns emit multiple instructions

[Andrew Stubbs]

A number of ARM/Thumb machine description patterns emit multiple instructions to perform one operation. Ideally, many of these patterns should be split up in order to allow the compiler to optimize the instruction sequence as well as it possibly can.

An *example* of a pattern *already* fixed can be found here:
  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42835

Note that the majority of these cases are not critical (hence they haven't been fixed yet), so there probably isn't a major win here.

[CodeSourcery Tracker ID #8453]

[Ramana Radhakrishnan (ramana)]

We should rewrite the multiple instruction emitting patterns into splits or define_insn_and_splits where applicable.