From ea9826ff77195c12dfba698d5fcb90786c949aa2 Mon Sep 17 00:00:00 2001
From: Lang Hames <lhames@gmail.com>
Date: Mon, 18 Oct 2021 22:11:16 -0700
Subject: [PATCH] [ORC-RT] Avoid switching out-of-band error value into
 __orc_rt::Error and back.

WrapperFunctionResult can already convey serialization errors as out-of-band
error values, so there's no need to wrap it in an Expected here. Removing the
wrapper simplifies the plumbing and call sites.
---
 compiler-rt/lib/orc/wrapper_function_utils.h | 30 +++++++++++-----------------
 1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/compiler-rt/lib/orc/wrapper_function_utils.h b/compiler-rt/lib/orc/wrapper_function_utils.h
index db6c897..a78c999 100644
--- a/compiler-rt/lib/orc/wrapper_function_utils.h
+++ b/compiler-rt/lib/orc/wrapper_function_utils.h
@@ -116,14 +116,14 @@ private:
 namespace detail {
 
 template <typename SPSArgListT, typename... ArgTs>
-Expected<WrapperFunctionResult>
+WrapperFunctionResult
 serializeViaSPSToWrapperFunctionResult(const ArgTs &...Args) {
   auto Result = WrapperFunctionResult::allocate(SPSArgListT::size(Args...));
   SPSOutputBuffer OB(Result.data(), Result.size());
   if (!SPSArgListT::serialize(OB, Args...))
-    return make_error<StringError>(
+    return WrapperFunctionResult::createOutOfBandError(
         "Error serializing arguments to blob in call");
-  return std::move(Result);
+  return Result;
 }
 
 template <typename RetT> class WrapperFunctionHandlerCaller {
@@ -171,12 +171,8 @@ public:
     auto HandlerResult = WrapperFunctionHandlerCaller<RetT>::call(
         std::forward<HandlerT>(H), Args, ArgIndices{});
 
-    if (auto Result = ResultSerializer<decltype(HandlerResult)>::serialize(
-            std::move(HandlerResult)))
-      return std::move(*Result);
-    else
-      return WrapperFunctionResult::createOutOfBandError(
-          toString(Result.takeError()));
+    return ResultSerializer<decltype(HandlerResult)>::serialize(
+        std::move(HandlerResult));
   }
 
 private:
@@ -186,7 +182,6 @@ private:
     SPSInputBuffer IB(ArgData, ArgSize);
     return SPSArgList<SPSTagTs...>::deserialize(IB, std::get<I>(Args)...);
   }
-
 };
 
 // Map function references to function types.
@@ -215,7 +210,7 @@ class WrapperFunctionHandlerHelper<RetT (ClassT::*)(ArgTs...) const,
 
 template <typename SPSRetTagT, typename RetT> class ResultSerializer {
 public:
-  static Expected<WrapperFunctionResult> serialize(RetT Result) {
+  static WrapperFunctionResult serialize(RetT Result) {
     return serializeViaSPSToWrapperFunctionResult<SPSArgList<SPSRetTagT>>(
         Result);
   }
@@ -223,7 +218,7 @@ public:
 
 template <typename SPSRetTagT> class ResultSerializer<SPSRetTagT, Error> {
 public:
-  static Expected<WrapperFunctionResult> serialize(Error Err) {
+  static WrapperFunctionResult serialize(Error Err) {
     return serializeViaSPSToWrapperFunctionResult<SPSArgList<SPSRetTagT>>(
         toSPSSerializable(std::move(Err)));
   }
@@ -232,7 +227,7 @@ public:
 template <typename SPSRetTagT, typename T>
 class ResultSerializer<SPSRetTagT, Expected<T>> {
 public:
-  static Expected<WrapperFunctionResult> serialize(Expected<T> E) {
+  static WrapperFunctionResult serialize(Expected<T> E) {
     return serializeViaSPSToWrapperFunctionResult<SPSArgList<SPSRetTagT>>(
         toSPSSerializable(std::move(E)));
   }
@@ -310,12 +305,11 @@ public:
     auto ArgBuffer =
         detail::serializeViaSPSToWrapperFunctionResult<SPSArgList<SPSTagTs...>>(
             Args...);
-    if (!ArgBuffer)
-      return ArgBuffer.takeError();
+    if (const char *ErrMsg = ArgBuffer.getOutOfBandError())
+      return make_error<StringError>(ErrMsg);
 
-    WrapperFunctionResult ResultBuffer =
-        __orc_rt_jit_dispatch(&__orc_rt_jit_dispatch_ctx, FnTag,
-                              ArgBuffer->data(), ArgBuffer->size());
+    WrapperFunctionResult ResultBuffer = __orc_rt_jit_dispatch(
+        &__orc_rt_jit_dispatch_ctx, FnTag, ArgBuffer.data(), ArgBuffer.size());
     if (auto ErrMsg = ResultBuffer.getOutOfBandError())
       return make_error<StringError>(ErrMsg);
 
-- 
2.7.4