This patch adds the X86FixupLEAs pass, which will reduce instruction
latency for certain models of the Intel Atom family, by converting
instructions into their equivalent LEA instructions, when it is both
useful and possible to do so.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180573 91177308-0d34-0410-b5e6-96231b3b80d8