- Two-address pass should not assume unfolding is always successful.

- Two-address pass should not assume unfolding is always successful.
- X86 unfolding should check if the instructions being unfolded has memoperands.
  If there is no memoperands, then it must assume conservative alignment. If this
  would introduce an expensive sse unaligned load / store, then unfoldMemoryOperand
  etc. should not unfold the instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107509 91177308-0d34-0410-b5e6-96231b3b80d8