[PATCH] [AArch64] Basic Sched Model for Cortex-A57

[Andrew Trick]

I'm not reviewing the A57 spec, but it looks good at the level of machine model defs. There's no fancy composition of SchedWrites, but the straightforward approach looks good to me.

================
Comment at: lib/Target/AArch64/AArch64SchedA57.td:104
@@ +103,3 @@
+// subtarget-defined types. As the modeled is refined, this will override most
+// of the above ShchedAlias mappings.
+
----------------
Typo: SchedAlias

http://reviews.llvm.org/D4008