s390x: simply ByteReverse using templates

Change-Id: I8ec751f578e2d7a790852670690797f19aba74e4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2570220Reviewed-by: Milad Fa <mfarazma@redhat.com>
Commit-Queue: Junliang Yan <junyan@redhat.com>
Cr-Commit-Position: refs/heads/master@{#71578}

src/execution/s390/simulator-s390.cc

@@ -2347,34 +2347,6 @@ void Simulator::PrintStopInfo(uint32_t code) {
 #define CheckOverflowForShiftLeft(src1, src2) \
   (((src1) << (src2)) >> (src2) != (src1))
 
-int16_t Simulator::ByteReverse(int16_t hword) {
-#if defined(__GNUC__)
-  return __builtin_bswap16(hword);
-#else
-  return (hword << 8) | ((hword >> 8) & 0x00FF);
-#endif
-}
-
-int32_t Simulator::ByteReverse(int32_t word) {
-#if defined(__GNUC__)
-  return __builtin_bswap32(word);
-#else
-  int32_t result = word << 24;
-  result |= (word << 8) & 0x00FF0000;
-  result |= (word >> 8) & 0x0000FF00;
-  result |= (word >> 24) & 0x00000FF;
-  return result;
-#endif
-}
-
-int64_t Simulator::ByteReverse(int64_t dword) {
-#if defined(__GNUC__)
-  return __builtin_bswap64(dword);
-#else
-#error unsupport __builtin_bswap64
-#endif
-}
-
 int Simulator::DecodeInstruction(Instruction* instr) {
   Opcode op = instr->S390OpcodeValue();
   DCHECK_NOT_NULL(EvalTable[op]);

src/execution/s390/simulator-s390.h

@@ -246,9 +246,38 @@ class Simulator : public SimulatorBase {
   void PrintStopInfo(uint32_t code);
 
   // Byte Reverse
-  inline int16_t ByteReverse(int16_t hword);
-  inline int32_t ByteReverse(int32_t word);
-  inline int64_t ByteReverse(int64_t dword);
+  static inline __uint128_t __builtin_bswap128(__uint128_t v) {
+    union {
+      uint64_t u64[2];
+      __uint128_t u128;
+    } res, val;
+    val.u128 = v;
+    res.u64[0] = __builtin_bswap64(val.u64[1]);
+    res.u64[1] = __builtin_bswap64(val.u64[0]);
+    return res.u128;
+  }
+
+  template <class T>
+  static inline T ByteReverse(T val) {
+    constexpr int size = sizeof(T);
+#define CASE(type, size_in_bits)                                              \
+  case sizeof(type): {                                                        \
+    type res = __builtin_bswap##size_in_bits(*reinterpret_cast<type*>(&val)); \
+    return *reinterpret_cast<T*>(&res);                                       \
+  }
+    switch (size) {
+      case 1:
+        return val;
+        CASE(uint16_t, 16);
+        CASE(uint32_t, 32);
+        CASE(uint64_t, 64);
+        CASE(__uint128_t, 128);
+      default:
+        UNREACHABLE();
+    }
+#undef CASE
+    return val;
+  }
 
   // Read and write memory.
   inline uint8_t ReadBU(intptr_t addr);