[ORC] Switch to asynchronous resolution in JITSymbolResolver.
authorLang Hames <lhames@gmail.com>
Tue, 25 Sep 2018 04:43:38 +0000 (04:43 +0000)
committerLang Hames <lhames@gmail.com>
Tue, 25 Sep 2018 04:43:38 +0000 (04:43 +0000)
Asynchronous resolution (where the caller receives a callback once the requested
set of symbols are resolved) is a core part of the new concurrent ORC APIs. This
change extends the asynchronous resolution model down to RuntimeDyld, which is
necessary to prevent deadlocks when compiling/linking on a fixed number of
threads: If RuntimeDyld's linking process were a blocking operation, then any
complete K-graph in a program will require at least K threads to link in the
worst case, as each thread would block waiting for all the others to complete.
Using callbacks instead allows the work to be passed between dependent threads
until it is complete.

For backwards compatibility, all existing RuntimeDyld functions will continue
to operate in blocking mode as before. This change will enable the introduction
of a new async finalization process in a subsequent patch to enable asynchronous
JIT linking.

llvm-svn: 342939

llvm/include/llvm/ExecutionEngine/JITSymbol.h
llvm/include/llvm/ExecutionEngine/Orc/Core.h
llvm/include/llvm/ExecutionEngine/Orc/Legacy.h
llvm/lib/ExecutionEngine/Orc/Legacy.cpp
llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp
llvm/lib/ExecutionEngine/RuntimeDyld/JITSymbol.cpp
llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldCheckerImpl.h
llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h

index 8956033..18b972e 100644 (file)
@@ -333,6 +333,7 @@ class JITSymbolResolver {
 public:
   using LookupSet = std::set<StringRef>;
   using LookupResult = std::map<StringRef, JITEvaluatedSymbol>;
+  using OnResolvedFunction = std::function<void(Expected<LookupResult>)>;
 
   virtual ~JITSymbolResolver() = default;
 
@@ -341,7 +342,8 @@ public:
   ///
   /// This method will return an error if any of the given symbols can not be
   /// resolved, or if the resolution process itself triggers an error.
-  virtual Expected<LookupResult> lookup(const LookupSet &Symbols) = 0;
+  virtual void lookup(const LookupSet &Symbols,
+                      OnResolvedFunction OnResolved) = 0;
 
   /// Returns the subset of the given symbols that should be materialized by
   /// the caller. Only weak/common symbols should be looked up, as strong
@@ -359,7 +361,7 @@ public:
   /// Performs lookup by, for each symbol, first calling
   ///        findSymbolInLogicalDylib and if that fails calling
   ///        findSymbol.
-  Expected<LookupResult> lookup(const LookupSet &Symbols) final;
+  void lookup(const LookupSet &Symbols, OnResolvedFunction OnResolved) final;
 
   /// Performs flags lookup by calling findSymbolInLogicalDylib and
   ///        returning the flags value for that symbol.
index 6440d81..c7a925c 100644 (file)
@@ -376,6 +376,7 @@ private:
 class AsynchronousSymbolQuery {
   friend class ExecutionSession;
   friend class JITDylib;
+  friend class JITSymbolResolverAdapter;
 
 public:
 
index b873049..4c6162a 100644 (file)
@@ -90,12 +90,13 @@ createSymbolResolver(GetResponsibilitySetFn &&GetResponsibilitySet,
       std::forward<LookupFn>(Lookup));
 }
 
+/// Legacy adapter. Remove once we kill off the old ORC layers.
 class JITSymbolResolverAdapter : public JITSymbolResolver {
 public:
   JITSymbolResolverAdapter(ExecutionSession &ES, SymbolResolver &R,
                            MaterializationResponsibility *MR);
   Expected<LookupSet> getResponsibilitySet(const LookupSet &Symbols) override;
-  Expected<LookupResult> lookup(const LookupSet &Symbols) override;
+  void lookup(const LookupSet &Symbols, OnResolvedFunction OnResolved) override;
 
 private:
   ExecutionSession &ES;
index 925729e..f61376a 100644 (file)
@@ -18,34 +18,34 @@ JITSymbolResolverAdapter::JITSymbolResolverAdapter(
     ExecutionSession &ES, SymbolResolver &R, MaterializationResponsibility *MR)
     : ES(ES), R(R), MR(MR) {}
 
-Expected<JITSymbolResolverAdapter::LookupResult>
-JITSymbolResolverAdapter::lookup(const LookupSet &Symbols) {
+void JITSymbolResolverAdapter::lookup(const LookupSet &Symbols,
+                                      OnResolvedFunction OnResolved) {
   SymbolNameSet InternedSymbols;
   for (auto &S : Symbols)
     InternedSymbols.insert(ES.getSymbolStringPool().intern(S));
 
-  auto LookupFn = [&, this](std::shared_ptr<AsynchronousSymbolQuery> Q,
-                            SymbolNameSet Unresolved) {
-    return R.lookup(std::move(Q), std::move(Unresolved));
-  };
+  auto OnResolvedWithUnwrap = [OnResolved](Expected<SymbolMap> InternedResult) {
+    if (!InternedResult) {
+      OnResolved(InternedResult.takeError());
+      return;
+    }
 
-  auto RegisterDependencies = [&](const SymbolDependenceMap &Deps) {
-    if (MR)
-      MR->addDependenciesForAll(Deps);
+    LookupResult Result;
+    for (auto &KV : *InternedResult)
+      Result[*KV.first] = std::move(KV.second);
+    OnResolved(Result);
   };
 
-  auto InternedResult =
-      ES.legacyLookup(std::move(LookupFn), std::move(InternedSymbols),
-                      false, RegisterDependencies);
-
-  if (!InternedResult)
-    return InternedResult.takeError();
+  auto Q = std::make_shared<AsynchronousSymbolQuery>(
+      InternedSymbols, OnResolvedWithUnwrap,
+      [this](Error Err) { ES.reportError(std::move(Err)); });
 
-  JITSymbolResolver::LookupResult Result;
-  for (auto &KV : *InternedResult)
-    Result[*KV.first] = KV.second;
-
-  return Result;
+  auto Unresolved = R.lookup(Q, InternedSymbols);
+  if (Unresolved.empty()) {
+    if (MR)
+      MR->addDependenciesForAll(Q->QueryRegistrations);
+  } else
+    ES.legacyFailQuery(*Q, make_error<SymbolsNotFound>(std::move(Unresolved)));
 }
 
 Expected<JITSymbolResolverAdapter::LookupSet>
index 3156897..d87078f 100644 (file)
@@ -18,30 +18,42 @@ class JITDylibSearchOrderResolver : public JITSymbolResolver {
 public:
   JITDylibSearchOrderResolver(MaterializationResponsibility &MR) : MR(MR) {}
 
-  Expected<LookupResult> lookup(const LookupSet &Symbols) {
+  void lookup(const LookupSet &Symbols, OnResolvedFunction OnResolved) {
     auto &ES = MR.getTargetJITDylib().getExecutionSession();
     SymbolNameSet InternedSymbols;
 
+    // Intern the requested symbols: lookup takes interned strings.
     for (auto &S : Symbols)
       InternedSymbols.insert(ES.getSymbolStringPool().intern(S));
 
+    // Build an OnResolve callback to unwrap the interned strings and pass them
+    // to the OnResolved callback.
+    // FIXME: Switch to move capture of OnResolved once we have c++14.
+    auto OnResolvedWithUnwrap =
+        [OnResolved](Expected<SymbolMap> InternedResult) {
+          if (!InternedResult) {
+            OnResolved(InternedResult.takeError());
+            return;
+          }
+
+          LookupResult Result;
+          for (auto &KV : *InternedResult)
+            Result[*KV.first] = std::move(KV.second);
+          OnResolved(Result);
+        };
+
+    // We're not waiting for symbols to be ready. Just log any errors.
+    auto OnReady = [&ES](Error Err) { ES.reportError(std::move(Err)); };
+
+    // Register dependencies for all symbols contained in this set.
     auto RegisterDependencies = [&](const SymbolDependenceMap &Deps) {
       MR.addDependenciesForAll(Deps);
     };
 
-    auto InternedResult =
-        MR.getTargetJITDylib().withSearchOrderDo([&](const JITDylibList &JDs) {
-          return ES.lookup(JDs, InternedSymbols, RegisterDependencies, false);
-        });
-
-    if (!InternedResult)
-      return InternedResult.takeError();
-
-    LookupResult Result;
-    for (auto &KV : *InternedResult)
-      Result[*KV.first] = std::move(KV.second);
-
-    return Result;
+    MR.getTargetJITDylib().withSearchOrderDo([&](const JITDylibList &JDs) {
+      ES.lookup(JDs, InternedSymbols, OnResolvedWithUnwrap, OnReady,
+                RegisterDependencies);
+    });
   }
 
   Expected<LookupSet> getResponsibilitySet(const LookupSet &Symbols) {
index d865216..b6ef8ad 100644 (file)
@@ -62,34 +62,42 @@ llvm::ARMJITSymbolFlags::fromObjectSymbol(const object::SymbolRef &Symbol) {
 /// Performs lookup by, for each symbol, first calling
 ///        findSymbolInLogicalDylib and if that fails calling
 ///        findSymbol.
-Expected<JITSymbolResolver::LookupResult>
-LegacyJITSymbolResolver::lookup(const LookupSet &Symbols) {
+void LegacyJITSymbolResolver::lookup(const LookupSet &Symbols,
+                                     OnResolvedFunction OnResolved) {
   JITSymbolResolver::LookupResult Result;
   for (auto &Symbol : Symbols) {
     std::string SymName = Symbol.str();
     if (auto Sym = findSymbolInLogicalDylib(SymName)) {
       if (auto AddrOrErr = Sym.getAddress())
         Result[Symbol] = JITEvaluatedSymbol(*AddrOrErr, Sym.getFlags());
-      else
-        return AddrOrErr.takeError();
-    } else if (auto Err = Sym.takeError())
-      return std::move(Err);
-    else {
+      else {
+        OnResolved(AddrOrErr.takeError());
+        return;
+      }
+    } else if (auto Err = Sym.takeError()) {
+      OnResolved(std::move(Err));
+      return;
+    } else {
       // findSymbolInLogicalDylib failed. Lets try findSymbol.
       if (auto Sym = findSymbol(SymName)) {
         if (auto AddrOrErr = Sym.getAddress())
           Result[Symbol] = JITEvaluatedSymbol(*AddrOrErr, Sym.getFlags());
-        else
-          return AddrOrErr.takeError();
-      } else if (auto Err = Sym.takeError())
-        return std::move(Err);
-      else
-        return make_error<StringError>("Symbol not found: " + Symbol,
-                                       inconvertibleErrorCode());
+        else {
+          OnResolved(AddrOrErr.takeError());
+          return;
+        }
+      } else if (auto Err = Sym.takeError()) {
+        OnResolved(std::move(Err));
+        return;
+      } else {
+        OnResolved(make_error<StringError>("Symbol not found: " + Symbol,
+                                           inconvertibleErrorCode()));
+        return;
+      }
     }
   }
 
-  return std::move(Result);
+  OnResolved(std::move(Result));
 }
 
 /// Performs flags lookup by calling findSymbolInLogicalDylib and
index 43c99b5..a651e78 100644 (file)
@@ -23,6 +23,8 @@
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/MutexGuard.h"
 
+#include <future>
+
 using namespace llvm;
 using namespace llvm::object;
 
@@ -996,42 +998,8 @@ void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
   }
 }
 
-Error RuntimeDyldImpl::resolveExternalSymbols() {
-  StringMap<JITEvaluatedSymbol> ExternalSymbolMap;
-
-  // Resolution can trigger emission of more symbols, so iterate until
-  // we've resolved *everything*.
-  {
-    JITSymbolResolver::LookupSet ResolvedSymbols;
-
-    while (true) {
-      JITSymbolResolver::LookupSet NewSymbols;
-
-      for (auto &RelocKV : ExternalSymbolRelocations) {
-        StringRef Name = RelocKV.first();
-        if (!Name.empty() && !GlobalSymbolTable.count(Name) &&
-            !ResolvedSymbols.count(Name))
-          NewSymbols.insert(Name);
-      }
-
-      if (NewSymbols.empty())
-        break;
-
-      auto NewResolverResults = Resolver.lookup(NewSymbols);
-      if (!NewResolverResults)
-        return NewResolverResults.takeError();
-
-      assert(NewResolverResults->size() == NewSymbols.size() &&
-             "Should have errored on unresolved symbols");
-
-      for (auto &RRKV : *NewResolverResults) {
-        assert(!ResolvedSymbols.count(RRKV.first) && "Redundant resolution?");
-        ExternalSymbolMap.insert(RRKV);
-        ResolvedSymbols.insert(RRKV.first);
-      }
-    }
-  }
-
+void RuntimeDyldImpl::applyExternalSymbolRelocations(
+    const StringMap<JITEvaluatedSymbol> ExternalSymbolMap) {
   while (!ExternalSymbolRelocations.empty()) {
 
     StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin();
@@ -1093,6 +1061,54 @@ Error RuntimeDyldImpl::resolveExternalSymbols() {
 
     ExternalSymbolRelocations.erase(i);
   }
+}
+
+Error RuntimeDyldImpl::resolveExternalSymbols() {
+  StringMap<JITEvaluatedSymbol> ExternalSymbolMap;
+
+  // Resolution can trigger emission of more symbols, so iterate until
+  // we've resolved *everything*.
+  {
+    JITSymbolResolver::LookupSet ResolvedSymbols;
+
+    while (true) {
+      JITSymbolResolver::LookupSet NewSymbols;
+
+      for (auto &RelocKV : ExternalSymbolRelocations) {
+        StringRef Name = RelocKV.first();
+        if (!Name.empty() && !GlobalSymbolTable.count(Name) &&
+            !ResolvedSymbols.count(Name))
+          NewSymbols.insert(Name);
+      }
+
+      if (NewSymbols.empty())
+        break;
+
+      auto NewSymbolsP = std::make_shared<
+          std::promise<Expected<JITSymbolResolver::LookupResult>>>();
+      auto NewSymbolsF = NewSymbolsP->get_future();
+      Resolver.lookup(NewSymbols,
+                      [=](Expected<JITSymbolResolver::LookupResult> Result) {
+                        NewSymbolsP->set_value(std::move(Result));
+                      });
+
+      auto NewResolverResults = NewSymbolsF.get();
+
+      if (!NewResolverResults)
+        return NewResolverResults.takeError();
+
+      assert(NewResolverResults->size() == NewSymbols.size() &&
+             "Should have errored on unresolved symbols");
+
+      for (auto &RRKV : *NewResolverResults) {
+        assert(!ResolvedSymbols.count(RRKV.first) && "Redundant resolution?");
+        ExternalSymbolMap.insert(RRKV);
+        ResolvedSymbols.insert(RRKV.first);
+      }
+    }
+  }
+
+  applyExternalSymbolRelocations(ExternalSymbolMap);
 
   return Error::success();
 }
index fa89068..79a1bbb 100644 (file)
@@ -16,6 +16,7 @@
 #include "llvm/MC/MCInst.h"
 #include "llvm/Support/Path.h"
 #include <cctype>
+#include <future>
 #include <memory>
 #include <utility>
 
@@ -729,15 +730,29 @@ bool RuntimeDyldCheckerImpl::checkAllRulesInBuffer(StringRef RulePrefix,
   return DidAllTestsPass && (NumRules != 0);
 }
 
+Expected<JITSymbolResolver::LookupResult> RuntimeDyldCheckerImpl::lookup(
+    const JITSymbolResolver::LookupSet &Symbols) const {
+  auto ResultP = std::make_shared<
+      std::promise<Expected<JITSymbolResolver::LookupResult>>>();
+  auto ResultF = ResultP->get_future();
+
+  getRTDyld().Resolver.lookup(
+      Symbols, [=](Expected<JITSymbolResolver::LookupResult> Result) {
+        ResultP->set_value(std::move(Result));
+      });
+  return ResultF.get();
+}
+
 bool RuntimeDyldCheckerImpl::isSymbolValid(StringRef Symbol) const {
   if (getRTDyld().getSymbol(Symbol))
     return true;
-  JITSymbolResolver::LookupSet Symbols({Symbol});
-  auto Result = getRTDyld().Resolver.lookup(Symbols);
+  auto Result = lookup({Symbol});
+
   if (!Result) {
     logAllUnhandledErrors(Result.takeError(), errs(), "RTDyldChecker: ");
     return false;
   }
+
   assert(Result->count(Symbol) && "Missing symbol result");
   return true;
 }
@@ -751,8 +766,7 @@ uint64_t RuntimeDyldCheckerImpl::getSymbolRemoteAddr(StringRef Symbol) const {
   if (auto InternalSymbol = getRTDyld().getSymbol(Symbol))
     return InternalSymbol.getAddress();
 
-  JITSymbolResolver::LookupSet Symbols({Symbol});
-  auto Result = getRTDyld().Resolver.lookup(Symbols);
+  auto Result = lookup({Symbol});
   if (!Result) {
     logAllUnhandledErrors(Result.takeError(), errs(), "RTDyldChecker: ");
     return 0;
index b462ef2..6da1a68 100644 (file)
@@ -41,6 +41,9 @@ private:
 
   RuntimeDyldImpl &getRTDyld() const { return *RTDyld.Dyld; }
 
+  Expected<JITSymbolResolver::LookupResult>
+  lookup(const JITSymbolResolver::LookupSet &Symbols) const;
+
   bool isSymbolValid(StringRef Symbol) const;
   uint64_t getSymbolLocalAddr(StringRef Symbol) const;
   uint64_t getSymbolRemoteAddr(StringRef Symbol) const;
index 9b33952..f01d310 100644 (file)
@@ -433,6 +433,9 @@ protected:
                        const ObjectFile &Obj, ObjSectionToIDMap &ObjSectionToID,
                        StubMap &Stubs) = 0;
 
+  void applyExternalSymbolRelocations(
+      const StringMap<JITEvaluatedSymbol> ExternalSymbolMap);
+
   /// Resolve relocations to external symbols.
   Error resolveExternalSymbols();