[PATCH] [AArch64] Improve and enable the SeparateConstOffsetFromGEP for AArch64 backend.

[Jingyue Wu]

SPEC2006 benchmarks are single-threaded, but this single thread can be
scheduled by the operating system on different CPUs (cores, hyperthreads,
etc.) in different time slices. I used to encounter fluctuation too and
fixed that using the taskset command. Not sure if that can help you too.

Also, I don't think x86 matters because this pass is only enabled in
AArch64 and NVPTX for now. I do feel a little worried on the 1%-2%
regression you observed on AArch64. It would be great if you can get a more
stable result.

Jingyue

http://reviews.llvm.org/D5864