[AArch64] Re-run load/store optimizer after aggressive tail duplication

The Load/Store Optimizer runs before Machine Block Placement. At O3 the
Tail Duplication Threshold is set to 4 instructions and this can create
new opportunities for the Load/Store Optimizer. It seems worthwhile to
run it once again.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@349338 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed