[SystemZ] Add hasSideEffects flag on Serialize instruction.

Serialize will perform a hardware serialization operation, and is
acting as a memory barrier. Therefore it must have the hasSideEffects
flag set so it will be treated as a global memory object.

Reviewed by Ulrich Weigand

llvm-svn: 257036

llvm/lib/Target/SystemZ/SystemZInstrInfo.td

@@ -1219,6 +1219,9 @@ def PFDRL : PrefetchRILPC<"pfdrl", 0xC62, z_prefetch>;
 // Atomic operations
 //===----------------------------------------------------------------------===//
 
+// A serialization instruction that acts as a barrier for all memory
+// accesses, which expands to "bcr 14, 0".
+let hasSideEffects = 1 in
 def Serialize : Alias<2, (outs), (ins), [(z_serialize)]>;
 
 let Predicates = [FeatureInterlockedAccess1], Defs = [CC] in {