[SystemZ] Add GRH32 for the high word of a GR64

The only thing this does on its own is make the definitions of RISB[HL]G
a bit more precise.  Those instructions are only used by the MC layer at
the moment, so no behavioral change is intended.  The class is needed by
later patches though.

llvm-svn: 191660
diff --git a/llvm/lib/Target/SystemZ/Disassembler/SystemZDisassembler.cpp b/llvm/lib/Target/SystemZ/Disassembler/SystemZDisassembler.cpp
index 79469b6..fc7fbf9 100644
--- a/llvm/lib/Target/SystemZ/Disassembler/SystemZDisassembler.cpp
+++ b/llvm/lib/Target/SystemZ/Disassembler/SystemZDisassembler.cpp
@@ -66,6 +66,12 @@
   return decodeRegisterClass(Inst, RegNo, SystemZMC::GR32Regs);
 }
 
+static DecodeStatus DecodeGRH32BitRegisterClass(MCInst &Inst, uint64_t RegNo,
+                                                uint64_t Address,
+                                                const void *Decoder) {
+  return decodeRegisterClass(Inst, RegNo, SystemZMC::GRH32Regs);
+}
+
 static DecodeStatus DecodeGR64BitRegisterClass(MCInst &Inst, uint64_t RegNo,
                                                uint64_t Address,
                                                const void *Decoder) {