[AArch64] Enable SeparateConstOffsetFromGEP, EarlyCSE and LICM passes on AArch64 backend.
SeparateConstOffsetFromGEP can gives more optimizaiton opportunities related to GEPs, which benefits EarlyCSE
and LICM. By enabling these passes we can have better address calculations and generate a better addressing
mode. Some SPEC 2006 benchmarks (astar, gobmk, namd) have obvious improvements on Cortex-A57.

Reviewed in http://reviews.llvm.org/D5864.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222331 91177308-0d34-0410-b5e6-96231b3b80d8
[AArch64] Disable useAA for Cortex-A57.
Using AA during CodeGen is very useful for in-order cores. It is less useful for ooo cores. Also I find
enabling useAA for Cortex-A57 may generate worse code for some test cases. If useAA in codegen is improved 
and benefical for ooo cores, we can enable it again.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222333 91177308-0d34-0410-b5e6-96231b3b80d8