[PATCH] Add peephole optimization to use LEA instructions of Intel Atom

[Nadav Rotem]

  Hi Preston,

  Why are you doing this optimization after register allocation, or even during instruction selection ?  If LEAs are better, why not use them all the time ?  Why are you going through the convertToThreeAddress, and not just do the conversion ?  Other users of convertToThreeAddress won't benefit from it because it is guarded by the isAfterRA flag, and you don't really need any of the logic in convertToThreeAddress ?

  Thanks,
  Nadav

http://llvm-reviews.chandlerc.com/D660