s390: exploit high-word facility for Smi Ops

src/s390/macro-assembler-s390.h

Index: src/s390/macro-assembler-s390.h
diff --git a/src/s390/macro-assembler-s390.h b/src/s390/macro-assembler-s390.h
index adb688b102403f080bd7ddbdb49f7263e1e85637..65dd162b395c584a8c4f42cb7b06c71f5c39051a 100644
--- a/src/s390/macro-assembler-s390.h
+++ b/src/s390/macro-assembler-s390.h
@@ -828,8 +828,10 @@ class MacroAssembler : public Assembler {
   void StoreRepresentation(Register src, const MemOperand& mem,
                            Representation r, Register scratch = no_reg);
 
-  void AddSmiLiteral(Register dst, Register src, Smi* smi, Register scratch);
-  void SubSmiLiteral(Register dst, Register src, Smi* smi, Register scratch);
+  void AddSmiLiteral(Register dst, Register src, Smi* smi,
+                     Register scratch = r0);
+  void SubSmiLiteral(Register dst, Register src, Smi* smi,
+                     Register scratch = r0);
   void CmpSmiLiteral(Register src1, Smi* smi, Register scratch);
   void CmpLogicalSmiLiteral(Register src1, Smi* smi, Register scratch);
   void AndSmiLiteral(Register dst, Register src, Smi* smi);