A64: Make the simulator sampling friendly.

src/a64/constants-a64.h

Index: src/a64/constants-a64.h
diff --git a/src/a64/constants-a64.h b/src/a64/constants-a64.h
index 625f9872e506ce56fbd7cab8e662385274fef2ba..4f43f13537c9b966177c69d2da7b890db0d7ff1e 100644
--- a/src/a64/constants-a64.h
+++ b/src/a64/constants-a64.h
@@ -707,12 +707,18 @@ enum MemBarrierOp {
   ISB             = MemBarrierFixed | 0x00000040
 };
 
-// Any load or store.
+// Any load or store (including pair).
 enum LoadStoreAnyOp {
   LoadStoreAnyFMask = 0x0a000000,
   LoadStoreAnyFixed = 0x08000000
 };
 
+// Any load pair or store pair.
+enum LoadStorePairAnyOp {
+  LoadStorePairAnyFMask = 0x3a000000,
+  LoadStorePairAnyFixed = 0x28000000
+};
+
 #define LOAD_STORE_PAIR_OP_LIST(V)  \
   V(STP, w,   0x00000000),          \
   V(LDP, w,   0x00400000),          \