[ORC] Add non-const WrapperFunctionResult::data method, simplify allocate.

WrapperFunctionResult no longer supports wrapping constant data, so this patch
adds a non-const data method. Since data can now be written through the data
method, the allocate method can be simplified to return a WrapperFunctionResult.

llvm/include/llvm/ExecutionEngine/Orc/Shared/WrapperFunctionUtils.h

@@ -89,6 +89,13 @@ public:
   }
 
   /// Get a pointer to the data contained in this instance.
+  char *data() {
+    assert((R.Size != 0 || R.Data.ValuePtr == nullptr) &&
+           "Cannot get data for out-of-band error value");
+    return R.Size > sizeof(R.Data.Value) ? R.Data.ValuePtr : R.Data.Value;
+  }
+
+  /// Get a const pointer to the data contained in this instance.
   const char *data() const {
     assert((R.Size != 0 || R.Data.ValuePtr == nullptr) &&
            "Cannot get data for out-of-band error value");
@@ -108,24 +115,19 @@ public:
 
   /// Create a WrapperFunctionResult with the given size and return a pointer
   /// to the underlying memory.
-  static char *allocate(WrapperFunctionResult &WFR, size_t Size) {
+  static WrapperFunctionResult allocate(size_t Size) {
     // Reset.
-    WFR = WrapperFunctionResult();
+    WrapperFunctionResult WFR;
     WFR.R.Size = Size;
-    char *DataPtr;
-    if (WFR.R.Size > sizeof(WFR.R.Data.Value)) {
-      DataPtr = (char *)malloc(WFR.R.Size);
-      WFR.R.Data.ValuePtr = DataPtr;
-    } else
-      DataPtr = WFR.R.Data.Value;
-    return DataPtr;
+    if (WFR.R.Size > sizeof(WFR.R.Data.Value))
+      WFR.R.Data.ValuePtr = (char *)malloc(WFR.R.Size);
+    return WFR;
   }
 
   /// Copy from the given char range.
   static WrapperFunctionResult copyFrom(const char *Source, size_t Size) {
-    WrapperFunctionResult WFR;
-    char *DataPtr = allocate(WFR, Size);
-    memcpy(DataPtr, Source, Size);
+    auto WFR = allocate(Size);
+    memcpy(WFR.data(), Source, Size);
     return WFR;
   }
 
@@ -174,10 +176,8 @@ namespace detail {
 template <typename SPSArgListT, typename... ArgTs>
 WrapperFunctionResult
 serializeViaSPSToWrapperFunctionResult(const ArgTs &...Args) {
-  WrapperFunctionResult Result;
-  char *DataPtr =
-      WrapperFunctionResult::allocate(Result, SPSArgListT::size(Args...));
-  SPSOutputBuffer OB(DataPtr, Result.size());
+  auto Result = WrapperFunctionResult::allocate(SPSArgListT::size(Args...));
+  SPSOutputBuffer OB(Result.data(), Result.size());
   if (!SPSArgListT::serialize(OB, Args...))
     return WrapperFunctionResult::createOutOfBandError(
         "Error serializing arguments to blob in call");

llvm/include/llvm/ExecutionEngine/Orc/TargetProcess/OrcRPCTPCServer.h

@@ -125,10 +125,9 @@ public:
     if (auto Err = deserializeSeq(C, Size))
       return Err;
 
-    WrapperFunctionResult Tmp;
-    char *Data = WrapperFunctionResult::allocate(Tmp, Size);
+    auto Tmp = WrapperFunctionResult::allocate(Size);
 
-    if (auto Err = C.readBytes(Data, Size))
+    if (auto Err = C.readBytes(Tmp.data(), Tmp.size()))
       return Err;
 
     E = std::move(Tmp);

llvm/unittests/ExecutionEngine/Orc/ExecutionSessionWrapperFunctionCallsTest.cpp

@@ -97,10 +97,8 @@ TEST(ExecutionSessionWrapperFunctionCalls, RegisterAsyncHandlerAndRun) {
 
   using ArgSerialization = SPSArgList<int32_t, int32_t>;
   size_t ArgBufferSize = ArgSerialization::size(1, 2);
-  WrapperFunctionResult ArgBuffer;
-  char *ArgBufferData =
-      WrapperFunctionResult::allocate(ArgBuffer, ArgBufferSize);
-  SPSOutputBuffer OB(ArgBufferData, ArgBufferSize);
+  auto ArgBuffer = WrapperFunctionResult::allocate(ArgBufferSize);
+  SPSOutputBuffer OB(ArgBuffer.data(), ArgBuffer.size());
   EXPECT_TRUE(ArgSerialization::serialize(OB, 1, 2));
 
   ES.runJITDispatchHandler(