[ORC] Add convenience methods for creating DynamicLibraryFallbackGenerators for

libraries on disk, and for the current process.

Avoids more boilerplate during JIT construction.

llvm-svn: 343430

include/llvm/ExecutionEngine/Orc/ExecutionUtils.h

@@ -215,8 +215,32 @@ public:
 class DynamicLibraryFallbackGenerator {
 public:
   using SymbolPredicate = std::function<bool(SymbolStringPtr)>;
+
+  static bool AllowAll(SymbolStringPtr Name) { return true; }
+
+  /// Create a DynamicLibraryFallbackGenerator that searches for symbols in the
+  /// given sys::DynamicLibrary.
+  /// Only symbols that match the 'Allow' predicate will be searched for.
   DynamicLibraryFallbackGenerator(sys::DynamicLibrary Dylib,
-                                  const DataLayout &DL, SymbolPredicate Allow);
+                                  const DataLayout &DL,
+                                  SymbolPredicate Allow = AllowAll);
+
+  /// Permanently loads the library at the given path and, on success, returns
+  /// a DynamicLibraryFallbackGenerator that will search it for symbol
+  /// definitions matching the Allow predicate.
+  /// On failure returns the reason the library failed to load.
+  static Expected<DynamicLibraryFallbackGenerator>
+  Load(const char *FileName, const DataLayout &DL,
+       SymbolPredicate Allow = AllowAll);
+
+  /// Creates a DynamicLibraryFallbackGenerator that searches for symbols in
+  /// the current process.
+  static Expected<DynamicLibraryFallbackGenerator>
+  CreateForCurrentProcess(const DataLayout &DL,
+                          SymbolPredicate Allow = AllowAll) {
+    return Load(nullptr, DL, std::move(Allow));
+  }
+
   SymbolNameSet operator()(JITDylib &JD, const SymbolNameSet &Names);
 
 private:

lib/ExecutionEngine/Orc/ExecutionUtils.cpp

@@ -174,6 +174,15 @@ DynamicLibraryFallbackGenerator::DynamicLibraryFallbackGenerator(
     : Dylib(std::move(Dylib)), Allow(std::move(Allow)),
       GlobalPrefix(DL.getGlobalPrefix()) {}
 
+Expected<DynamicLibraryFallbackGenerator> DynamicLibraryFallbackGenerator::Load(
+    const char *FileName, const DataLayout &DL, SymbolPredicate Allow) {
+  std::string ErrMsg;
+  auto Lib = sys::DynamicLibrary::getPermanentLibrary(FileName, &ErrMsg);
+  if (!Lib.isValid())
+    return make_error<StringError>(std::move(ErrMsg), inconvertibleErrorCode());
+  return DynamicLibraryFallbackGenerator(std::move(Lib), DL, std::move(Allow));
+}
+
 SymbolNameSet DynamicLibraryFallbackGenerator::
 operator()(JITDylib &JD, const SymbolNameSet &Names) {
   orc::SymbolNameSet Added;

tools/lli/lli.cpp

@@ -752,15 +752,6 @@ static orc::IRTransformLayer2::TransformFunction createDebugDumper() {
 int runOrcLazyJIT(const char *ProgName) {
   // Start setting up the JIT environment.
 
-  // First add lli's symbols into the JIT's search space.
-  std::string ErrMsg;
-  sys::DynamicLibrary LibLLI =
-      sys::DynamicLibrary::getPermanentLibrary(nullptr, &ErrMsg);
-  if (!LibLLI.isValid()) {
-    errs() << "Error loading lli symbols: " << ErrMsg << ".\n";
-    return 1;
-  }
-
   // Parse the main module.
   orc::ThreadSafeContext TSCtx(llvm::make_unique<LLVMContext>());
   SMDiagnostic Err;
@@ -802,9 +793,8 @@ int runOrcLazyJIT(const char *ProgName) {
     }
     return Dump(std::move(TSM), R);
   });
-  J->getMainJITDylib().setFallbackDefinitionGenerator(
-      orc::DynamicLibraryFallbackGenerator(
-          std::move(LibLLI), DL, [](orc::SymbolStringPtr) { return true; }));
+  J->getMainJITDylib().setFallbackDefinitionGenerator(ExitOnErr(
+      orc::DynamicLibraryFallbackGenerator::CreateForCurrentProcess(DL)));
 
   orc::MangleAndInterner Mangle(J->getExecutionSession(), DL);
   orc::LocalCXXRuntimeOverrides2 CXXRuntimeOverrides;