S390: Fix LA overflow in return sequence

src/s390/macro-assembler-s390.cc

Index: src/s390/macro-assembler-s390.cc
diff --git a/src/s390/macro-assembler-s390.cc b/src/s390/macro-assembler-s390.cc
index 6ae50eea082f3505172048aab719ab5a307aaca9..8465fd71c618d7ec4f4b462b372db3856aa6cf53 100644
--- a/src/s390/macro-assembler-s390.cc
+++ b/src/s390/macro-assembler-s390.cc
@@ -154,7 +154,14 @@ void MacroAssembler::Call(Handle<Code> code, RelocInfo::Mode rmode,
 
 void MacroAssembler::Drop(int count) {
   if (count > 0) {
-    la(sp, MemOperand(sp, count * kPointerSize));
+    int total = count * kPointerSize;
+    if (is_uint12(total)) {
+      la(sp, MemOperand(sp, total));
+    } else if (is_int20(total)) {
+      lay(sp, MemOperand(sp, total));
+    } else {
+      AddP(sp, Operand(total));
+    }
   }
 }