[ORC-RT] Add SPS serialization for span<const char> / SPSSequence<char>.

Author: lhames

compiler-rt/lib/orc/simple_packed_serialization.h

@@ -354,6 +354,27 @@ class SPSSerializationTraits<SPSSequence<SPSElementTagT>, SequenceT,
   }
 };
 
+/// Trivial serialization / deserialization for span<char>
+template <> class SPSSerializationTraits<SPSSequence<char>, span<const char>> {
+public:
+  static size_t size(const span<const char> &S) {
+    return SPSArgList<uint64_t>::size(static_cast<uint64_t>(S.size())) +
+           S.size();
+  }
+  static bool serialize(SPSOutputBuffer &OB, const span<const char> &S) {
+    if (!SPSArgList<uint64_t>::serialize(OB, static_cast<uint64_t>(S.size())))
+      return false;
+    return OB.write(S.data(), S.size());
+  }
+  static bool deserialize(SPSInputBuffer &IB, span<const char> &S) {
+    uint64_t Size;
+    if (!SPSArgList<uint64_t>::deserialize(IB, Size))
+      return false;
+    S = span<const char>(IB.data(), Size);
+    return IB.skip(Size);
+  }
+};
+
 /// SPSTuple serialization for std::pair.
 template <typename SPSTagT1, typename SPSTagT2, typename T1, typename T2>
 class SPSSerializationTraits<SPSTuple<SPSTagT1, SPSTagT2>, std::pair<T1, T2>> {

compiler-rt/lib/orc/unittests/simple_packed_serialization_test.cpp

@@ -130,6 +130,30 @@ TEST(SimplePackedSerializationTest, StringViewCharSequenceSerialization) {
   blobSerializationRoundTrip<SPSString, string_view>(string_view(HW));
 }
 
+TEST(SimplePackedSerializationTest, SpanSerialization) {
+  const char Data[] = {3, 2, 1, 0, 1, 2, 3}; // Span should handle nulls.
+  span<const char> OutS(Data, sizeof(Data));
+
+  size_t Size = SPSArgList<SPSSequence<char>>::size(OutS);
+  auto Buffer = std::make_unique<char[]>(Size);
+  SPSOutputBuffer OB(Buffer.get(), Size);
+
+  EXPECT_TRUE(SPSArgList<SPSSequence<char>>::serialize(OB, OutS));
+
+  SPSInputBuffer IB(Buffer.get(), Size);
+
+  span<const char> InS;
+
+  EXPECT_TRUE(SPSArgList<SPSSequence<char>>::deserialize(IB, InS));
+
+  // Check that the serialized and deserialized values match.
+  EXPECT_EQ(InS.size(), OutS.size());
+  EXPECT_EQ(memcmp(OutS.data(), InS.data(), InS.size()), 0);
+
+  // Check that the span points directly to the input buffer.
+  EXPECT_EQ(InS.data(), Buffer.get() + sizeof(uint64_t));
+}
+
 TEST(SimplePackedSerializationTest, StdPairSerialization) {
   std::pair<int32_t, std::string> P(42, "foo");
   blobSerializationRoundTrip<SPSTuple<int32_t, SPSString>,