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

[Renato Golin]

================
Comment at: lib/Target/AArch64/AArch64FixCortexA53_835769.cpp:155
@@ +154,3 @@
+
+  assert(false && "Expected to find instruction");
+}
----------------
shouldn't this be an llvm_unreachable instead?

================
Comment at: test/CodeGen/AArch64/aarch64-fix-cortex-a53-835769.ll:36
@@ +35,3 @@
+; CHECK-NOWORKAROUND-NEXT:	madd
+; CHECK-BASIC-PASS-DISABLED-LABEL: f_load_madd_64:
+; CHECK-BASIC-PASS-DISABLED:  ldr
----------------
If BASIC-PASS-DISABLED == NOWORKAROUND, why have two?

http://reviews.llvm.org/D5721