[PATCH] [AArch64] Add workaround for Cortex-A53 erratum (835769)

[Tim Northover]

================
Comment at: lib/Target/AArch64/AArch64FixCortexA53_835769.cpp:143
@@ +142,3 @@
+  for (MachineBasicBlock *S : MBB.predecessors())
+    if (S == PrevBB)
+      return S;
----------------
t.p.northover wrote:
> This doesn't necessarily mean it was a fallthrough. Particularly at -O0 a block may happen to be before another in layout order but contain a real branch anyway.
Actually, AnalyzeBranch is probably what you want to use here, if you find some way to go ahead with the NOP at end solution.

http://reviews.llvm.org/D5721