llvm/lib/ExecutionEngine/Orc/SimpleRemoteEPC.cpp - llvm-project - Git at Google

 //===------- SimpleRemoteEPC.cpp -- Simple remote executor control --------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/ExecutionEngine/Orc/SimpleRemoteEPC.h"
 #include "llvm/ExecutionEngine/Orc/CallProxiesSPS.h"
 #include "llvm/ExecutionEngine/Orc/EPCGenericDylibManagerSPS.h"
 #include "llvm/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManagerSPS.h"
 #include "llvm/ExecutionEngine/Orc/EPCGenericMemoryAccessSPS.h"
 #include "llvm/ExecutionEngine/Orc/Shared/OrcRTBridge.h"
 #include "llvm/Support/FormatVariadic.h"

 #define DEBUG_TYPE "orc"

 namespace llvm {
 namespace orc {

 SimpleRemoteEPC::~SimpleRemoteEPC() {
 #ifndef NDEBUG
   std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
   assert(Disconnected && "Destroyed without disconnection");
 #endif // NDEBUG
 }

 Expected<int32_t> SimpleRemoteEPC::runAsMain(ExecutorAddr MainFnAddr,
                                              ArrayRef<std::string> Args) {
   int64_t Result = 0;
   if (auto Err = callSPSWrapper<rt::sps_ci::CallMain::SPSSig>(
           RunAsMainAddr, Result, MainFnAddr, Args))
     return std::move(Err);
   return Result;
 }

 void SimpleRemoteEPC::callWrapperAsync(ExecutorAddr WrapperFnAddr,
                                        IncomingWFRHandler OnComplete,
                                        ArrayRef<char> ArgBuffer) {
   uint64_t SeqNo;
   {
     std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
     SeqNo = getNextSeqNo();
     assert(!PendingCallWrapperResults.count(SeqNo) && "SeqNo already in use");
     PendingCallWrapperResults[SeqNo] = std::move(OnComplete);
   }

   if (auto Err = sendMessage(SimpleRemoteEPCOpcode::CallWrapper, SeqNo,
                              WrapperFnAddr, ArgBuffer)) {
     IncomingWFRHandler H;

     // We just registered OnComplete, but there may be a race between this
     // thread returning from sendMessage and handleDisconnect being called from
     // the transport's listener thread. If handleDisconnect gets there first
     // then it will have failed 'H' for us. If we get there first (or if
     // handleDisconnect already ran) then we need to take care of it.
     {
       std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
       auto I = PendingCallWrapperResults.find(SeqNo);
       if (I != PendingCallWrapperResults.end()) {
         H = std::move(I->second);
         PendingCallWrapperResults.erase(I);
       }
     }

     if (H)
       H(shared::WrapperFunctionBuffer::createOutOfBandError("disconnecting"));

     getExecutionSession().reportError(std::move(Err));
   }
 }

 Expected<std::unique_ptr<jitlink::JITLinkMemoryManager>>
 SimpleRemoteEPC::createDefaultMemoryManager() {
   return sps::createEPCGenericJITLinkMemoryManager(getExecutionSession());
 }

 Expected<std::unique_ptr<DylibManager>>
 SimpleRemoteEPC::createDefaultDylibMgr() {
   return sps::createEPCGenericDylibManager(getExecutionSession());
 }

 Expected<std::unique_ptr<MemoryAccess>>
 SimpleRemoteEPC::createDefaultMemoryAccess() {
   return sps::createEPCGenericMemoryAccess(getExecutionSession());
 }

 Error SimpleRemoteEPC::disconnect() {
   // disconnect is idempotent, so the first caller owns the hangup. There is
   // also nothing to announce to an executor that has already announced its own
   // departure.
   bool SendHangup = false;
   {
     std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
     SendHangup = !LocalHangup && !RemoteHangup;
     LocalHangup = true;
   }

   // Tell the executor we're going away, so that it can distinguish this from
   // losing us unexpectedly. Best-effort: if the send fails there is nothing to
   // do but tear down anyway, and the executor will report the disconnection as
   // unexpected. A locally requested disconnect is orderly, so the hangup
   // carries a success value.
   if (SendHangup) {
     auto Payload = encodeHangupPayload(Error::success());
     if (auto Err = sendMessage(SimpleRemoteEPCOpcode::Hangup, 0, ExecutorAddr(),
                                {Payload.data(), Payload.size()}))
       consumeError(std::move(Err));
   }

   T->disconnect();
   D->shutdown();
   std::unique_lock<std::mutex> Lock(SimpleRemoteEPCMutex);
   DisconnectCV.wait(Lock, [this] { return Disconnected; });
   return std::move(DisconnectErr);
 }

 Expected<SimpleRemoteEPCTransportClient::HandleMessageAction>
 SimpleRemoteEPC::handleMessage(SimpleRemoteEPCOpcode OpC, uint64_t SeqNo,
                                ExecutorAddr TagAddr,
                                shared::WrapperFunctionBuffer ArgBytes) {

   LLVM_DEBUG({
     dbgs() << "SimpleRemoteEPC::handleMessage: opc = ";
     switch (OpC) {
     case SimpleRemoteEPCOpcode::Setup:
       dbgs() << "Setup";
       assert(SeqNo == 0 && "Non-zero SeqNo for Setup?");
       assert(!TagAddr && "Non-zero TagAddr for Setup?");
       break;
     case SimpleRemoteEPCOpcode::Hangup:
       dbgs() << "Hangup";
       assert(SeqNo == 0 && "Non-zero SeqNo for Hangup?");
       assert(!TagAddr && "Non-zero TagAddr for Hangup?");
       break;
     case SimpleRemoteEPCOpcode::Result:
       dbgs() << "Result";
       assert(!TagAddr && "Non-zero TagAddr for Result?");
       break;
     case SimpleRemoteEPCOpcode::CallWrapper:
       dbgs() << "CallWrapper";
       break;
     }
     dbgs() << ", seqno = " << SeqNo << ", tag-addr = " << TagAddr
            << ", arg-buffer = " << formatv("{0:x}", ArgBytes.size())
            << " bytes\n";
   });

   using UT = std::underlying_type_t<SimpleRemoteEPCOpcode>;
   if (static_cast<UT>(OpC) > static_cast<UT>(SimpleRemoteEPCOpcode::LastOpC))
     return make_error<StringError>("Unexpected opcode",
                                    inconvertibleErrorCode());

   switch (OpC) {
   case SimpleRemoteEPCOpcode::Setup:
     if (auto Err = handleSetup(SeqNo, TagAddr, std::move(ArgBytes)))
       return std::move(Err);
     break;
   case SimpleRemoteEPCOpcode::Hangup:
     T->disconnect();
     {
       std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
       RemoteHangup = true;
     }
     if (auto Err = handleHangup(std::move(ArgBytes)))
       return std::move(Err);
     return EndSession;
   case SimpleRemoteEPCOpcode::Result:
     if (auto Err = handleResult(SeqNo, TagAddr, std::move(ArgBytes)))
       return std::move(Err);
     break;
   case SimpleRemoteEPCOpcode::CallWrapper:
     handleCallWrapper(SeqNo, TagAddr, std::move(ArgBytes));
     break;
   }
   return ContinueSession;
 }

 void SimpleRemoteEPC::handleDisconnect(Error Err) {
   LLVM_DEBUG({
     dbgs() << "SimpleRemoteEPC::handleDisconnect: "
            << (Err ? "failure" : "success") << "\n";
   });

   PendingCallWrapperResultsMap TmpPending;

   {
     std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
     std::swap(TmpPending, PendingCallWrapperResults);
   }

   for (auto &KV : TmpPending)
     KV.second(
         shared::WrapperFunctionBuffer::createOutOfBandError("disconnecting"));

   std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);

   // If the transport reported no error, but neither side announced the end of
   // the session, then the executor went away without telling us. The cause is
   // not knowable from here -- it may have crashed, been killed, or become
   // unreachable -- so report what was observed rather than a cause.
   //
   // A missing hangup is evidence, not proof: a hangup can also be lost in
   // transit, since closing a TCP socket with unread data queued sends an RST,
   // which can discard bytes the peer had already delivered. We accept that
   // rather than draining the read side before closing -- the cost is a
   // misleading diagnostic on a session that is ending regardless, whereas a
   // drain risks stalling teardown on a peer that never closes.
   Error DisconnectReason =
       (!Err && !LocalHangup && !RemoteHangup)
           ? make_error<StringError>("Connection closed without hangup",
                                     inconvertibleErrorCode())
           : std::move(Err);

   DisconnectErr =
       joinErrors(std::move(DisconnectErr), std::move(DisconnectReason));
   Disconnected = true;
   DisconnectCV.notify_all();
 }

 Error SimpleRemoteEPC::sendMessage(SimpleRemoteEPCOpcode OpC, uint64_t SeqNo,
                                    ExecutorAddr TagAddr,
                                    ArrayRef<char> ArgBytes) {
   assert(OpC != SimpleRemoteEPCOpcode::Setup &&
          "SimpleRemoteEPC sending Setup message? That's the wrong direction.");

   LLVM_DEBUG({
     dbgs() << "SimpleRemoteEPC::sendMessage: opc = ";
     switch (OpC) {
     case SimpleRemoteEPCOpcode::Hangup:
       dbgs() << "Hangup";
       assert(SeqNo == 0 && "Non-zero SeqNo for Hangup?");
       assert(!TagAddr && "Non-zero TagAddr for Hangup?");
       break;
     case SimpleRemoteEPCOpcode::Result:
       dbgs() << "Result";
       assert(!TagAddr && "Non-zero TagAddr for Result?");
       break;
     case SimpleRemoteEPCOpcode::CallWrapper:
       dbgs() << "CallWrapper";
       break;
     default:
       llvm_unreachable("Invalid opcode");
     }
     dbgs() << ", seqno = " << SeqNo << ", tag-addr = " << TagAddr
            << ", arg-buffer = " << formatv("{0:x}", ArgBytes.size())
            << " bytes\n";
   });
   auto Err = T->sendMessage(OpC, SeqNo, TagAddr, ArgBytes);
   LLVM_DEBUG({
     if (Err)
       dbgs() << "  \\--> SimpleRemoteEPC::sendMessage failed\n";
   });
   return Err;
 }

 Error SimpleRemoteEPC::handleSetup(uint64_t SeqNo, ExecutorAddr TagAddr,
                                    shared::WrapperFunctionBuffer ArgBytes) {
   if (SeqNo != 0)
     return make_error<StringError>("Setup packet SeqNo not zero",
                                    inconvertibleErrorCode());

   if (TagAddr)
     return make_error<StringError>("Setup packet TagAddr not zero",
                                    inconvertibleErrorCode());

   std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
   auto I = PendingCallWrapperResults.find(0);
   assert(PendingCallWrapperResults.size() == 1 &&
          I != PendingCallWrapperResults.end() &&
          "Setup message handler not connectly set up");
   auto SetupMsgHandler = std::move(I->second);
   PendingCallWrapperResults.erase(I);

   auto WFR =
       shared::WrapperFunctionBuffer::copyFrom(ArgBytes.data(), ArgBytes.size());
   SetupMsgHandler(std::move(WFR));
   return Error::success();
 }

 Error SimpleRemoteEPC::setup() {
   using namespace SimpleRemoteEPCDefaultBootstrapSymbolNames;

   std::promise<MSVCPExpected<SimpleRemoteEPCExecutorInfo>> EIP;
   auto EIF = EIP.get_future();

   // Prepare a handler for the setup packet.
   PendingCallWrapperResults[0] =
     RunInPlace()(
       [&](shared::WrapperFunctionBuffer SetupMsgBytes) {
         if (const char *ErrMsg = SetupMsgBytes.getOutOfBandError()) {
           EIP.set_value(
               make_error<StringError>(ErrMsg, inconvertibleErrorCode()));
           return;
         }
         using SPSSerialize =
             shared::SPSArgList<shared::SPSSimpleRemoteEPCExecutorInfo>;
         shared::SPSInputBuffer IB(SetupMsgBytes.data(), SetupMsgBytes.size());
         SimpleRemoteEPCExecutorInfo EI;
         if (SPSSerialize::deserialize(IB, EI))
           EIP.set_value(EI);
         else
           EIP.set_value(make_error<StringError>(
               "Could not deserialize setup message", inconvertibleErrorCode()));
       });

   // Start the transport.
   if (auto Err = T->start())
     return Err;

   // Wait for setup packet to arrive.
   auto EI = EIF.get();
   if (!EI) {
     T->disconnect();
     return EI.takeError();
   }

   LLVM_DEBUG({
     dbgs() << "SimpleRemoteEPC received setup message:\n"
            << "  Triple: " << EI->TargetTriple << "\n"
            << "  Page size: " << EI->PageSize << "\n"
            << "  Bootstrap map" << (EI->BootstrapMap.empty() ? " empty" : ":")
            << "\n";
     for (const auto &KV : EI->BootstrapMap)
       dbgs() << "    " << KV.first() << ": " << KV.second.size()
              << "-byte SPS encoded buffer\n";
     dbgs() << "  Bootstrap symbols"
            << (EI->BootstrapSymbols.empty() ? " empty" : ":") << "\n";
     for (const auto &KV : EI->BootstrapSymbols)
       dbgs() << "    " << KV.first() << ": " << KV.second << "\n";
   });
   TargetTriple = Triple(EI->TargetTriple);
   PageSize = EI->PageSize;
   BootstrapMap = std::move(EI->BootstrapMap);
   BootstrapSymbols = std::move(EI->BootstrapSymbols);

   BootstrapSymbols[rt::DispatchName] = BootstrapSymbols[DispatchFnName];
   BootstrapSymbols[rt::DispatchCtxName] =
       BootstrapSymbols[ExecutorSessionObjectName];

   if (auto Err =
           getBootstrapSymbols({{RunAsMainAddr, rt::sps_ci::CallMain::Name}}))
     return Err;

   return Error::success();
 }

 Error SimpleRemoteEPC::handleResult(uint64_t SeqNo, ExecutorAddr TagAddr,
                                     shared::WrapperFunctionBuffer ArgBytes) {
   IncomingWFRHandler SendResult;

   if (TagAddr)
     return make_error<StringError>("Unexpected TagAddr in result message",
                                    inconvertibleErrorCode());

   {
     std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
     auto I = PendingCallWrapperResults.find(SeqNo);
     if (I == PendingCallWrapperResults.end())
       return make_error<StringError>("No call for sequence number " +
                                          Twine(SeqNo),
                                      inconvertibleErrorCode());
     SendResult = std::move(I->second);
     PendingCallWrapperResults.erase(I);
     releaseSeqNo(SeqNo);
   }

   auto WFR =
       shared::WrapperFunctionBuffer::copyFrom(ArgBytes.data(), ArgBytes.size());
   SendResult(std::move(WFR));
   return Error::success();
 }

 void SimpleRemoteEPC::handleCallWrapper(
     uint64_t RemoteSeqNo, ExecutorAddr TagAddr,
     shared::WrapperFunctionBuffer ArgBytes) {
   assert(ES && "No ExecutionSession attached");
   D->dispatch(makeGenericNamedTask(
       [this, RemoteSeqNo, TagAddr, ArgBytes = std::move(ArgBytes)]() mutable {
         ES->runJITDispatchHandler(
             [this, RemoteSeqNo](shared::WrapperFunctionBuffer WFR) {
               if (auto Err =
                       sendMessage(SimpleRemoteEPCOpcode::Result, RemoteSeqNo,
                                   ExecutorAddr(), {WFR.data(), WFR.size()}))
                 getExecutionSession().reportError(std::move(Err));
             },
             TagAddr, std::move(ArgBytes));
       },
       "callWrapper task"));
 }

 Error SimpleRemoteEPC::handleHangup(shared::WrapperFunctionBuffer ArgBytes) {
   return decodeHangupPayload(std::move(ArgBytes));
 }

 } // end namespace orc
 } // end namespace llvm
	//===------- SimpleRemoteEPC.cpp -- Simple remote executor control --------===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/ExecutionEngine/Orc/SimpleRemoteEPC.h"
	#include "llvm/ExecutionEngine/Orc/CallProxiesSPS.h"
	#include "llvm/ExecutionEngine/Orc/EPCGenericDylibManagerSPS.h"
	#include "llvm/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManagerSPS.h"
	#include "llvm/ExecutionEngine/Orc/EPCGenericMemoryAccessSPS.h"
	#include "llvm/ExecutionEngine/Orc/Shared/OrcRTBridge.h"
	#include "llvm/Support/FormatVariadic.h"

	#define DEBUG_TYPE "orc"

	namespace llvm {
	namespace orc {

	SimpleRemoteEPC::~SimpleRemoteEPC() {
	#ifndef NDEBUG
	std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
	assert(Disconnected && "Destroyed without disconnection");
	#endif // NDEBUG
	}

	Expected<int32_t> SimpleRemoteEPC::runAsMain(ExecutorAddr MainFnAddr,
	ArrayRef<std::string> Args) {
	int64_t Result = 0;
	if (auto Err = callSPSWrapper<rt::sps_ci::CallMain::SPSSig>(
	RunAsMainAddr, Result, MainFnAddr, Args))
	return std::move(Err);
	return Result;
	}

	void SimpleRemoteEPC::callWrapperAsync(ExecutorAddr WrapperFnAddr,
	IncomingWFRHandler OnComplete,
	ArrayRef<char> ArgBuffer) {
	uint64_t SeqNo;
	{
	std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
	SeqNo = getNextSeqNo();
	assert(!PendingCallWrapperResults.count(SeqNo) && "SeqNo already in use");
	PendingCallWrapperResults[SeqNo] = std::move(OnComplete);
	}

	if (auto Err = sendMessage(SimpleRemoteEPCOpcode::CallWrapper, SeqNo,
	WrapperFnAddr, ArgBuffer)) {
	IncomingWFRHandler H;

	// We just registered OnComplete, but there may be a race between this
	// thread returning from sendMessage and handleDisconnect being called from
	// the transport's listener thread. If handleDisconnect gets there first
	// then it will have failed 'H' for us. If we get there first (or if
	// handleDisconnect already ran) then we need to take care of it.
	{
	std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
	auto I = PendingCallWrapperResults.find(SeqNo);
	if (I != PendingCallWrapperResults.end()) {
	H = std::move(I->second);
	PendingCallWrapperResults.erase(I);
	}
	}

	if (H)
	H(shared::WrapperFunctionBuffer::createOutOfBandError("disconnecting"));

	getExecutionSession().reportError(std::move(Err));
	}
	}

	Expected<std::unique_ptr<jitlink::JITLinkMemoryManager>>
	SimpleRemoteEPC::createDefaultMemoryManager() {
	return sps::createEPCGenericJITLinkMemoryManager(getExecutionSession());
	}

	Expected<std::unique_ptr<DylibManager>>
	SimpleRemoteEPC::createDefaultDylibMgr() {
	return sps::createEPCGenericDylibManager(getExecutionSession());
	}

	Expected<std::unique_ptr<MemoryAccess>>
	SimpleRemoteEPC::createDefaultMemoryAccess() {
	return sps::createEPCGenericMemoryAccess(getExecutionSession());
	}

	Error SimpleRemoteEPC::disconnect() {
	// disconnect is idempotent, so the first caller owns the hangup. There is
	// also nothing to announce to an executor that has already announced its own
	// departure.
	bool SendHangup = false;
	{
	std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
	SendHangup = !LocalHangup && !RemoteHangup;
	LocalHangup = true;
	}

	// Tell the executor we're going away, so that it can distinguish this from
	// losing us unexpectedly. Best-effort: if the send fails there is nothing to
	// do but tear down anyway, and the executor will report the disconnection as
	// unexpected. A locally requested disconnect is orderly, so the hangup
	// carries a success value.
	if (SendHangup) {
	auto Payload = encodeHangupPayload(Error::success());
	if (auto Err = sendMessage(SimpleRemoteEPCOpcode::Hangup, 0, ExecutorAddr(),
	{Payload.data(), Payload.size()}))
	consumeError(std::move(Err));
	}

	T->disconnect();
	D->shutdown();
	std::unique_lock<std::mutex> Lock(SimpleRemoteEPCMutex);
	DisconnectCV.wait(Lock, [this] { return Disconnected; });
	return std::move(DisconnectErr);
	}

	Expected<SimpleRemoteEPCTransportClient::HandleMessageAction>
	SimpleRemoteEPC::handleMessage(SimpleRemoteEPCOpcode OpC, uint64_t SeqNo,
	ExecutorAddr TagAddr,
	shared::WrapperFunctionBuffer ArgBytes) {

	LLVM_DEBUG({
	dbgs() << "SimpleRemoteEPC::handleMessage: opc = ";
	switch (OpC) {
	case SimpleRemoteEPCOpcode::Setup:
	dbgs() << "Setup";
	assert(SeqNo == 0 && "Non-zero SeqNo for Setup?");
	assert(!TagAddr && "Non-zero TagAddr for Setup?");
	break;
	case SimpleRemoteEPCOpcode::Hangup:
	dbgs() << "Hangup";
	assert(SeqNo == 0 && "Non-zero SeqNo for Hangup?");
	assert(!TagAddr && "Non-zero TagAddr for Hangup?");
	break;
	case SimpleRemoteEPCOpcode::Result:
	dbgs() << "Result";
	assert(!TagAddr && "Non-zero TagAddr for Result?");
	break;
	case SimpleRemoteEPCOpcode::CallWrapper:
	dbgs() << "CallWrapper";
	break;
	}
	dbgs() << ", seqno = " << SeqNo << ", tag-addr = " << TagAddr
	<< ", arg-buffer = " << formatv("{0:x}", ArgBytes.size())
	<< " bytes\n";
	});

	using UT = std::underlying_type_t<SimpleRemoteEPCOpcode>;
	if (static_cast<UT>(OpC) > static_cast<UT>(SimpleRemoteEPCOpcode::LastOpC))
	return make_error<StringError>("Unexpected opcode",
	inconvertibleErrorCode());

	switch (OpC) {
	case SimpleRemoteEPCOpcode::Setup:
	if (auto Err = handleSetup(SeqNo, TagAddr, std::move(ArgBytes)))
	return std::move(Err);
	break;
	case SimpleRemoteEPCOpcode::Hangup:
	T->disconnect();
	{
	std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
	RemoteHangup = true;
	}
	if (auto Err = handleHangup(std::move(ArgBytes)))
	return std::move(Err);
	return EndSession;
	case SimpleRemoteEPCOpcode::Result:
	if (auto Err = handleResult(SeqNo, TagAddr, std::move(ArgBytes)))
	return std::move(Err);
	break;
	case SimpleRemoteEPCOpcode::CallWrapper:
	handleCallWrapper(SeqNo, TagAddr, std::move(ArgBytes));
	break;
	}
	return ContinueSession;
	}

	void SimpleRemoteEPC::handleDisconnect(Error Err) {
	LLVM_DEBUG({
	dbgs() << "SimpleRemoteEPC::handleDisconnect: "
	<< (Err ? "failure" : "success") << "\n";
	});

	PendingCallWrapperResultsMap TmpPending;

	{
	std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
	std::swap(TmpPending, PendingCallWrapperResults);
	}

	for (auto &KV : TmpPending)
	KV.second(
	shared::WrapperFunctionBuffer::createOutOfBandError("disconnecting"));

	std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);

	// If the transport reported no error, but neither side announced the end of
	// the session, then the executor went away without telling us. The cause is
	// not knowable from here -- it may have crashed, been killed, or become
	// unreachable -- so report what was observed rather than a cause.
	//
	// A missing hangup is evidence, not proof: a hangup can also be lost in
	// transit, since closing a TCP socket with unread data queued sends an RST,
	// which can discard bytes the peer had already delivered. We accept that
	// rather than draining the read side before closing -- the cost is a
	// misleading diagnostic on a session that is ending regardless, whereas a
	// drain risks stalling teardown on a peer that never closes.
	Error DisconnectReason =
	(!Err && !LocalHangup && !RemoteHangup)
	? make_error<StringError>("Connection closed without hangup",
	inconvertibleErrorCode())
	: std::move(Err);

	DisconnectErr =
	joinErrors(std::move(DisconnectErr), std::move(DisconnectReason));
	Disconnected = true;
	DisconnectCV.notify_all();
	}

	Error SimpleRemoteEPC::sendMessage(SimpleRemoteEPCOpcode OpC, uint64_t SeqNo,
	ExecutorAddr TagAddr,
	ArrayRef<char> ArgBytes) {
	assert(OpC != SimpleRemoteEPCOpcode::Setup &&
	"SimpleRemoteEPC sending Setup message? That's the wrong direction.");

	LLVM_DEBUG({
	dbgs() << "SimpleRemoteEPC::sendMessage: opc = ";
	switch (OpC) {
	case SimpleRemoteEPCOpcode::Hangup:
	dbgs() << "Hangup";
	assert(SeqNo == 0 && "Non-zero SeqNo for Hangup?");
	assert(!TagAddr && "Non-zero TagAddr for Hangup?");
	break;
	case SimpleRemoteEPCOpcode::Result:
	dbgs() << "Result";
	assert(!TagAddr && "Non-zero TagAddr for Result?");
	break;
	case SimpleRemoteEPCOpcode::CallWrapper:
	dbgs() << "CallWrapper";
	break;
	default:
	llvm_unreachable("Invalid opcode");
	}
	dbgs() << ", seqno = " << SeqNo << ", tag-addr = " << TagAddr
	<< ", arg-buffer = " << formatv("{0:x}", ArgBytes.size())
	<< " bytes\n";
	});
	auto Err = T->sendMessage(OpC, SeqNo, TagAddr, ArgBytes);
	LLVM_DEBUG({
	if (Err)
	dbgs() << " \\--> SimpleRemoteEPC::sendMessage failed\n";
	});
	return Err;
	}

	Error SimpleRemoteEPC::handleSetup(uint64_t SeqNo, ExecutorAddr TagAddr,
	shared::WrapperFunctionBuffer ArgBytes) {
	if (SeqNo != 0)
	return make_error<StringError>("Setup packet SeqNo not zero",
	inconvertibleErrorCode());

	if (TagAddr)
	return make_error<StringError>("Setup packet TagAddr not zero",
	inconvertibleErrorCode());

	std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
	auto I = PendingCallWrapperResults.find(0);
	assert(PendingCallWrapperResults.size() == 1 &&
	I != PendingCallWrapperResults.end() &&
	"Setup message handler not connectly set up");
	auto SetupMsgHandler = std::move(I->second);
	PendingCallWrapperResults.erase(I);

	auto WFR =
	shared::WrapperFunctionBuffer::copyFrom(ArgBytes.data(), ArgBytes.size());
	SetupMsgHandler(std::move(WFR));
	return Error::success();
	}

	Error SimpleRemoteEPC::setup() {
	using namespace SimpleRemoteEPCDefaultBootstrapSymbolNames;

	std::promise<MSVCPExpected<SimpleRemoteEPCExecutorInfo>> EIP;
	auto EIF = EIP.get_future();

	// Prepare a handler for the setup packet.
	PendingCallWrapperResults[0] =
	RunInPlace()(
	[&](shared::WrapperFunctionBuffer SetupMsgBytes) {
	if (const char *ErrMsg = SetupMsgBytes.getOutOfBandError()) {
	EIP.set_value(
	make_error<StringError>(ErrMsg, inconvertibleErrorCode()));
	return;
	}
	using SPSSerialize =
	shared::SPSArgList<shared::SPSSimpleRemoteEPCExecutorInfo>;
	shared::SPSInputBuffer IB(SetupMsgBytes.data(), SetupMsgBytes.size());
	SimpleRemoteEPCExecutorInfo EI;
	if (SPSSerialize::deserialize(IB, EI))
	EIP.set_value(EI);
	else
	EIP.set_value(make_error<StringError>(
	"Could not deserialize setup message", inconvertibleErrorCode()));
	});

	// Start the transport.
	if (auto Err = T->start())
	return Err;

	// Wait for setup packet to arrive.
	auto EI = EIF.get();
	if (!EI) {
	T->disconnect();
	return EI.takeError();
	}

	LLVM_DEBUG({
	dbgs() << "SimpleRemoteEPC received setup message:\n"
	<< " Triple: " << EI->TargetTriple << "\n"
	<< " Page size: " << EI->PageSize << "\n"
	<< " Bootstrap map" << (EI->BootstrapMap.empty() ? " empty" : ":")
	<< "\n";
	for (const auto &KV : EI->BootstrapMap)
	dbgs() << " " << KV.first() << ": " << KV.second.size()
	<< "-byte SPS encoded buffer\n";
	dbgs() << " Bootstrap symbols"
	<< (EI->BootstrapSymbols.empty() ? " empty" : ":") << "\n";
	for (const auto &KV : EI->BootstrapSymbols)
	dbgs() << " " << KV.first() << ": " << KV.second << "\n";
	});
	TargetTriple = Triple(EI->TargetTriple);
	PageSize = EI->PageSize;
	BootstrapMap = std::move(EI->BootstrapMap);
	BootstrapSymbols = std::move(EI->BootstrapSymbols);

	BootstrapSymbols[rt::DispatchName] = BootstrapSymbols[DispatchFnName];
	BootstrapSymbols[rt::DispatchCtxName] =
	BootstrapSymbols[ExecutorSessionObjectName];

	if (auto Err =
	getBootstrapSymbols({{RunAsMainAddr, rt::sps_ci::CallMain::Name}}))
	return Err;

	return Error::success();
	}

	Error SimpleRemoteEPC::handleResult(uint64_t SeqNo, ExecutorAddr TagAddr,
	shared::WrapperFunctionBuffer ArgBytes) {
	IncomingWFRHandler SendResult;

	if (TagAddr)
	return make_error<StringError>("Unexpected TagAddr in result message",
	inconvertibleErrorCode());

	{
	std::lock_guard<std::mutex> Lock(SimpleRemoteEPCMutex);
	auto I = PendingCallWrapperResults.find(SeqNo);
	if (I == PendingCallWrapperResults.end())
	return make_error<StringError>("No call for sequence number " +
	Twine(SeqNo),
	inconvertibleErrorCode());
	SendResult = std::move(I->second);
	PendingCallWrapperResults.erase(I);
	releaseSeqNo(SeqNo);
	}

	auto WFR =
	shared::WrapperFunctionBuffer::copyFrom(ArgBytes.data(), ArgBytes.size());
	SendResult(std::move(WFR));
	return Error::success();
	}

	void SimpleRemoteEPC::handleCallWrapper(
	uint64_t RemoteSeqNo, ExecutorAddr TagAddr,
	shared::WrapperFunctionBuffer ArgBytes) {
	assert(ES && "No ExecutionSession attached");
	D->dispatch(makeGenericNamedTask(
	[this, RemoteSeqNo, TagAddr, ArgBytes = std::move(ArgBytes)]() mutable {
	ES->runJITDispatchHandler(
	[this, RemoteSeqNo](shared::WrapperFunctionBuffer WFR) {
	if (auto Err =
	sendMessage(SimpleRemoteEPCOpcode::Result, RemoteSeqNo,
	ExecutorAddr(), {WFR.data(), WFR.size()}))
	getExecutionSession().reportError(std::move(Err));
	},
	TagAddr, std::move(ArgBytes));
	},
	"callWrapper task"));
	}

	Error SimpleRemoteEPC::handleHangup(shared::WrapperFunctionBuffer ArgBytes) {
	return decodeHangupPayload(std::move(ArgBytes));
	}

	} // end namespace orc
	} // end namespace llvm