s390: Remove RSubI on s390 and optimize ConstantI

src/crankshaft/s390/lithium-s390.h

Index: src/crankshaft/s390/lithium-s390.h
diff --git a/src/crankshaft/s390/lithium-s390.h b/src/crankshaft/s390/lithium-s390.h
index b946d4f271c8a65483d874f6700248067c27f8a2..e2c3180212be85de9ccf5df5d0aab4d74a752aa3 100644
--- a/src/crankshaft/s390/lithium-s390.h
+++ b/src/crankshaft/s390/lithium-s390.h
@@ -133,7 +133,6 @@ class LCodeGen;
   V(StringCharFromCode)                      \
   V(StringCompareAndBranch)                  \
   V(SubI)                                    \
-  V(RSubI)                                   \
   V(TaggedToI)                               \
   V(ThisFunction)                            \
   V(TransitionElementsKind)                  \
@@ -178,6 +177,8 @@ class LInstruction : public ZoneObject {
 #undef DECLARE_OPCODE
   };
 
+  static const char* GetOpcodeName(Opcode op);
+
   virtual Opcode opcode() const = 0;
 
 // Declare non-virtual type testers for all leaf IR classes.
@@ -1090,20 +1091,6 @@ class LSubI final : public LTemplateInstruction<1, 2, 0> {
   DECLARE_HYDROGEN_ACCESSOR(Sub)
 };
 
-class LRSubI final : public LTemplateInstruction<1, 2, 0> {
- public:
-  LRSubI(LOperand* left, LOperand* right) {
-    inputs_[0] = left;
-    inputs_[1] = right;
-  }
-
-  LOperand* left() { return inputs_[0]; }
-  LOperand* right() { return inputs_[1]; }
-
-  DECLARE_CONCRETE_INSTRUCTION(RSubI, "rsub-i")
-  DECLARE_HYDROGEN_ACCESSOR(Sub)
-};
-
 class LConstantI final : public LTemplateInstruction<1, 0, 0> {
  public:
   DECLARE_CONCRETE_INSTRUCTION(ConstantI, "constant-i")
@@ -2141,7 +2128,6 @@ class LChunkBuilder final : public LChunkBuilderBase {
 
   LInstruction* DoMultiplyAdd(HMul* mul, HValue* addend);
   LInstruction* DoMultiplySub(HValue* minuend, HMul* mul);
-  LInstruction* DoRSub(HSub* instr);
 
   static bool HasMagicNumberForDivisor(int32_t divisor);