S390: Use TM instead of TMLL in case of memory operand.

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 2970b01b8757bcb661fc2211d9d08e1b1bec2f76..6d2dcd3bd08c083a7cce69f09f32361016ee599e 100644
--- a/src/s390/macro-assembler-s390.h
+++ b/src/s390/macro-assembler-s390.h
@@ -1552,6 +1552,16 @@ class MacroAssembler : public Assembler {
 
   inline void TestIfSmi(Register value) { tmll(value, Operand(1)); }
 
+  inline void TestIfSmi(MemOperand value) {
+    if (is_uint12(value.offset())) {
+      tm(value, Operand(1));
+    } else if (is_int20(value.offset())) {
+      tmy(value, Operand(1));
+    } else {
+      UNIMPLEMENTED();

[JoranSiu, 2016/12/19 16:25:33]

A bit concerned about this unimplemented path... as it'll likely be a matter of
time before we hit this. :|  

+    }
+  }
+
   inline void TestIfPositiveSmi(Register value, Register scratch) {
     STATIC_ASSERT((kSmiTagMask | kSmiSignMask) ==
                   (intptr_t)(1UL << (kBitsPerPointer - 1) | 1));