From a779e0266fae5dcf64acfba0e165e2f0ac12a745 Mon Sep 17 00:00:00 2001
From: Lang Hames <lhames@gmail.com>
Date: Mon, 21 May 2018 21:11:21 +0000
Subject: [PATCH] [ORC] Lookup now returns an error if any symbols are not
 found.

Also tightens the behavior of ExecutionSession::failQuery. Queries can usually
only be failed by marking a symbol as failed-to-materialize, but
ExecutionSession::failQuery provides a second route, and both routes may be
executed from different threads. In the case that a query has already been
failed due to a materialization error, ExecutionSession::failQuery will
direct the error to ExecutionSession::reportError instead.

llvm-svn: 332898
---
 include/llvm/ExecutionEngine/Orc/Core.h | 16 +++++++++++
 lib/ExecutionEngine/Orc/Core.cpp        | 35 +++++++++++++++++++++++--
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/include/llvm/ExecutionEngine/Orc/Core.h b/include/llvm/ExecutionEngine/Orc/Core.h
index d06e5bf9430..06e6a0f3469 100644
--- a/include/llvm/ExecutionEngine/Orc/Core.h
+++ b/include/llvm/ExecutionEngine/Orc/Core.h
@@ -79,6 +79,20 @@ private:
   SymbolNameSet Symbols;
 };
 
+/// Used to notify clients when symbols can not be found during a lookup.
+class SymbolsNotFound : public ErrorInfo<SymbolsNotFound> {
+public:
+  static char ID;
+
+  SymbolsNotFound(SymbolNameSet Symbols);
+  std::error_code convertToErrorCode() const override;
+  void log(raw_ostream &OS) const override;
+  const SymbolNameSet &getSymbols() const { return Symbols; }
+
+private:
+  SymbolNameSet Symbols;
+};
+
 /// Tracks responsibility for materialization, and mediates interactions between
 /// MaterializationUnits and VSOs.
 ///
@@ -366,6 +380,8 @@ private:
 
   void removeQueryDependence(VSO &V, const SymbolStringPtr &Name);
 
+  bool canStillFail();
+
   void handleFailed(Error Err);
 
   void detach();
diff --git a/lib/ExecutionEngine/Orc/Core.cpp b/lib/ExecutionEngine/Orc/Core.cpp
index ded8bddb468..760e2561ba6 100644
--- a/lib/ExecutionEngine/Orc/Core.cpp
+++ b/lib/ExecutionEngine/Orc/Core.cpp
@@ -20,6 +20,7 @@ namespace llvm {
 namespace orc {
 
 char FailedToMaterialize::ID = 0;
+char SymbolsNotFound::ID = 0;
 
 void MaterializationUnit::anchor() {}
 void SymbolResolver::anchor() {}
@@ -110,11 +111,31 @@ void FailedToMaterialize::log(raw_ostream &OS) const {
   OS << "Failed to materialize symbols: " << Symbols;
 }
 
+SymbolsNotFound::SymbolsNotFound(SymbolNameSet Symbols)
+    : Symbols(std::move(Symbols)) {
+  assert(!this->Symbols.empty() && "Can not fail to resolve an empty set");
+}
+
+std::error_code SymbolsNotFound::convertToErrorCode() const {
+  return orcError(OrcErrorCode::UnknownORCError);
+}
+
+void SymbolsNotFound::log(raw_ostream &OS) const {
+  OS << "Symbols not found: " << Symbols;
+}
+
 void ExecutionSessionBase::failQuery(AsynchronousSymbolQuery &Q, Error Err) {
+  bool DeliveredError = true;
   runSessionLocked([&]() -> void {
     Q.detach();
-    Q.handleFailed(std::move(Err));
+    if (Q.canStillFail())
+      Q.handleFailed(std::move(Err));
+    else
+      DeliveredError = false;
   });
+
+  if (!DeliveredError)
+    reportError(std::move(Err));
 }
 
 AsynchronousSymbolQuery::AsynchronousSymbolQuery(
@@ -160,6 +181,10 @@ void AsynchronousSymbolQuery::handleFullyReady() {
   NotifySymbolsReady = SymbolsReadyCallback();
 }
 
+bool AsynchronousSymbolQuery::canStillFail() {
+  return (NotifySymbolsResolved || NotifySymbolsReady);
+}
+
 void AsynchronousSymbolQuery::handleFailed(Error Err) {
   assert(QueryRegistrations.empty() && ResolvedSymbols.empty() &&
          NotYetResolvedCount == 0 && NotYetReadyCount == 0 &&
@@ -902,7 +927,13 @@ Expected<SymbolMap> lookup(const std::vector<VSO *> &VSOs, SymbolNameSet Names)
     UnresolvedSymbols = V->lookup(Query, UnresolvedSymbols);
   }
 
-  // FIXME: Error out if there are remaining unresolved symbols.
+  if (!UnresolvedSymbols.empty()) {
+    // If there are unresolved symbols then the query will never return.
+    // Fail it with ES.failQuery.
+    auto &ES = (*VSOs.begin())->getExecutionSession();
+    ES.failQuery(*Query,
+                 make_error<SymbolsNotFound>(std::move(UnresolvedSymbols)));
+  }
 
 #if LLVM_ENABLE_THREADS
   auto ResultFuture = PromisedResult.get_future();