[clang-repl] Expose CreateExecutor() and ResetExecutor() in extended Interpreter interface (#84460)

IncrementalExecutor is an implementation detail of the Interpreter. In
order to test extended features properly, we must be able to setup and
tear down the executor manually.

clang/include/clang/Interpreter/Interpreter.h

@@ -96,7 +96,6 @@ class Interpreter {
   // An optional parser for CUDA offloading
   std::unique_ptr<IncrementalParser> DeviceParser;
 
-  llvm::Error CreateExecutor();
   unsigned InitPTUSize = 0;
 
   // This member holds the last result of the value printing. It's a class
@@ -114,6 +113,14 @@ protected:
   // That's useful for testing and out-of-tree clients.
   Interpreter(std::unique_ptr<CompilerInstance> CI, llvm::Error &Err);
 
+  // Create the internal IncrementalExecutor, or re-create it after calling
+  // ResetExecutor().
+  llvm::Error CreateExecutor();
+
+  // Delete the internal IncrementalExecutor. This causes a hard shutdown of the
+  // JIT engine. In particular, it doesn't run cleanup or destructors.
+  void ResetExecutor();
+
   // Lazily construct the RuntimeInterfaceBuilder. The provided instance will be
   // used for the entire lifetime of the interpreter. The default implementation
   // targets the in-process __clang_Interpreter runtime. Override this to use a

clang/lib/Interpreter/Interpreter.cpp

@@ -375,6 +375,10 @@ Interpreter::Parse(llvm::StringRef Code) {
 llvm::Error Interpreter::CreateExecutor() {
   const clang::TargetInfo &TI =
       getCompilerInstance()->getASTContext().getTargetInfo();
+  if (IncrExecutor)
+    return llvm::make_error<llvm::StringError>("Operation failed. "
+                                               "Execution engine exists",
+                                               std::error_code());
   llvm::Error Err = llvm::Error::success();
   auto Executor = std::make_unique<IncrementalExecutor>(*TSCtx, Err, TI);
   if (!Err)
@@ -383,6 +387,8 @@ llvm::Error Interpreter::CreateExecutor() {
   return Err;
 }
 
+void Interpreter::ResetExecutor() { IncrExecutor.reset(); }
+
 llvm::Error Interpreter::Execute(PartialTranslationUnit &T) {
   assert(T.TheModule);
   if (!IncrExecutor) {

clang/unittests/Interpreter/CMakeLists.txt

@@ -4,6 +4,7 @@ set(LLVM_LINK_COMPONENTS
   OrcJIT
   Support
   TargetParser
+  TestingSupport
   )
 
 add_clang_unittest(ClangReplInterpreterTests

clang/unittests/Interpreter/InterpreterExtensionsTest.cpp

@@ -27,6 +27,30 @@
 using namespace clang;
 namespace {
 
+class TestCreateResetExecutor : public Interpreter {
+public:
+  TestCreateResetExecutor(std::unique_ptr<CompilerInstance> CI,
+                          llvm::Error &Err)
+      : Interpreter(std::move(CI), Err) {}
+
+  llvm::Error testCreateExecutor() { return Interpreter::CreateExecutor(); }
+
+  void resetExecutor() { Interpreter::ResetExecutor(); }
+};
+
+TEST(InterpreterExtensionsTest, ExecutorCreateReset) {
+  clang::IncrementalCompilerBuilder CB;
+  llvm::Error ErrOut = llvm::Error::success();
+  TestCreateResetExecutor Interp(cantFail(CB.CreateCpp()), ErrOut);
+  cantFail(std::move(ErrOut));
+  cantFail(Interp.testCreateExecutor());
+  Interp.resetExecutor();
+  cantFail(Interp.testCreateExecutor());
+  EXPECT_THAT_ERROR(Interp.testCreateExecutor(),
+                    llvm::FailedWithMessage("Operation failed. "
+                                            "Execution engine exists"));
+}
+
 class RecordRuntimeIBMetrics : public Interpreter {
   struct NoopRuntimeInterfaceBuilder : public RuntimeInterfaceBuilder {
     NoopRuntimeInterfaceBuilder(Sema &S) : S(S) {}