[clang-repl] Include consistency using the default clang actions.

This patch improves the code reuse of the actions system and adds several
improvements for easier debugging via clang-repl --debug-only=clang-repl.

The change inimproves the consistency of the TUKind when actions are handled
within a WrapperFrontendAction. In this case instead of falling back to default
TU_Complete, we forward to the TUKind of the ASTContext which presumably was
created by the intended action. This enables the incremental infrastructure to
reuse code.

This patch also clones the first llvm::Module because the first PTU now can come
from -include A.h and the presumption of llvm::Module being empty does not hold.
The changes are a first step to fix the issues with `clang-repl --cuda`.

Author: vgvassilev

clang/include/clang/Frontend/FrontendAction.h

@@ -21,6 +21,7 @@
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/LangOptions.h"
 #include "clang/Frontend/ASTUnit.h"
+#include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/FrontendOptions.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Error.h"
@@ -185,7 +186,12 @@ class FrontendAction {
   virtual bool usesPreprocessorOnly() const = 0;
 
   /// For AST-based actions, the kind of translation unit we're handling.
-  virtual TranslationUnitKind getTranslationUnitKind() { return TU_Complete; }
+  virtual TranslationUnitKind getTranslationUnitKind() {
+    // The ASTContext, if exists, knows the exact TUKind of the frondend.
+    if (Instance && Instance->hasASTContext())
+      return Instance->getASTContext().TUKind;
+    return TU_Complete;
+  }
 
   /// Does this action support use with PCH?
   virtual bool hasPCHSupport() const { return true; }

clang/include/clang/Interpreter/Interpreter.h

@@ -177,7 +177,8 @@ class Interpreter {
 
   CodeGenerator *getCodeGen() const;
   std::unique_ptr<llvm::Module> GenModule();
-  PartialTranslationUnit &RegisterPTU(TranslationUnitDecl *TU);
+  PartialTranslationUnit &RegisterPTU(TranslationUnitDecl *TU,
+                                      std::unique_ptr<llvm::Module> M = {});
 
   // A cache for the compiled destructors used to for de-allocation of managed
   // clang::Values.

clang/include/clang/Interpreter/PartialTranslationUnit.h

@@ -31,6 +31,9 @@ struct PartialTranslationUnit {
 
   /// The llvm IR produced for the input.
   std::unique_ptr<llvm::Module> TheModule;
+  bool operator==(const PartialTranslationUnit &other) {
+    return other.TUPart == TUPart && other.TheModule == TheModule;
+  }
 };
 } // namespace clang
 

clang/lib/Interpreter/CMakeLists.txt

@@ -10,7 +10,8 @@ set(LLVM_LINK_COMPONENTS
    Support
    Target
    TargetParser
-  )
+   TransformUtils
+   )
 
 if (EMSCRIPTEN AND "lld" IN_LIST LLVM_ENABLE_PROJECTS)
   set(WASM_SRC Wasm.cpp)

clang/lib/Interpreter/Interpreter.cpp

@@ -50,6 +50,9 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/TargetParser/Host.h"
+#include "llvm/Transforms/Utils/Cloning.h" // for CloneModule
+
+#define DEBUG_TYPE "clang-repl"
 
 using namespace clang;
 // FIXME: Figure out how to unify with namespace init_convenience from
@@ -339,19 +342,8 @@ class IncrementalAction : public WrapperFrontendAction {
   }
 
   void ExecuteAction() override {
-    CompilerInstance &CI = getCompilerInstance();
-    assert(CI.hasPreprocessor() && "No PP!");
-
-    // Use a code completion consumer?
-    CodeCompleteConsumer *CompletionConsumer = nullptr;
-    if (CI.hasCodeCompletionConsumer())
-      CompletionConsumer = &CI.getCodeCompletionConsumer();
-
-    Preprocessor &PP = CI.getPreprocessor();
-    PP.EnterMainSourceFile();
-
-    if (!CI.hasSema())
-      CI.createSema(getTranslationUnitKind(), CompletionConsumer);
+    WrapperFrontendAction::ExecuteAction();
+    getCompilerInstance().getSema().CurContext = nullptr;
   }
 
   // Do not terminate after processing the input. This allows us to keep various
@@ -385,27 +377,29 @@ Interpreter::Interpreter(std::unique_ptr<CompilerInstance> Instance,
     return;
   CI->ExecuteAction(*Act);
 
-  ASTContext &C = CI->getASTContext();
-
   IncrParser = std::make_unique<IncrementalParser>(*CI, ErrOut);
 
   if (ErrOut)
     return;
 
   if (getCodeGen()) {
     CachedInCodeGenModule = GenModule();
+    // The initial PTU is filled by `-include` or by CUDA includes
+    // automatically.
+    if (!CI->getPreprocessorOpts().Includes.empty()) {
+      // We can't really directly pass the CachedInCodeGenModule to the Jit
+      // because it will steal it, causing dangling references as explained in
+      // Interpreter::Execute
+      auto M = llvm::CloneModule(*CachedInCodeGenModule);
+      ASTContext &C = CI->getASTContext();
+      RegisterPTU(C.getTranslationUnitDecl(), std::move(M));
+    }
     if (llvm::Error Err = CreateExecutor()) {
       ErrOut = joinErrors(std::move(ErrOut), std::move(Err));
       return;
     }
   }
 
-  // The initial PTU is filled by `-include` or by CUDA includes automatically.
-  RegisterPTU(C.getTranslationUnitDecl());
-
-  // Prepare the IncrParser for input.
-  llvm::cantFail(Parse(""));
-
   // Not all frontends support code-generation, e.g. ast-dump actions don't
   if (getCodeGen()) {
     // Process the PTUs that came from initialization. For example -include will
@@ -535,14 +529,25 @@ size_t Interpreter::getEffectivePTUSize() const {
   return PTUs.size() - InitPTUSize;
 }
 
-PartialTranslationUnit &Interpreter::RegisterPTU(TranslationUnitDecl *TU) {
+PartialTranslationUnit &
+Interpreter::RegisterPTU(TranslationUnitDecl *TU,
+                         std::unique_ptr<llvm::Module> M /*={}*/) {
   PTUs.emplace_back(PartialTranslationUnit());
   PartialTranslationUnit &LastPTU = PTUs.back();
   LastPTU.TUPart = TU;
 
-  if (std::unique_ptr<llvm::Module> M = GenModule())
-    LastPTU.TheModule = std::move(M);
+  if (!M)
+    M = GenModule();
+
+  assert((!getCodeGen() || M) && "Must have a llvm::Module at this point");
 
+  LastPTU.TheModule = std::move(M);
+  LLVM_DEBUG(llvm::dbgs() << "compile-ptu " << PTUs.size() - 1
+                          << ": [TU=" << LastPTU.TUPart);
+  if (LastPTU.TheModule)
+    LLVM_DEBUG(llvm::dbgs() << ", M=" << LastPTU.TheModule.get() << " ("
+                            << LastPTU.TheModule->getName() << ")");
+  LLVM_DEBUG(llvm::dbgs() << "]\n");
   return LastPTU;
 }
 
@@ -615,6 +620,14 @@ void Interpreter::ResetExecutor() { IncrExecutor.reset(); }
 
 llvm::Error Interpreter::Execute(PartialTranslationUnit &T) {
   assert(T.TheModule);
+  LLVM_DEBUG(llvm::dbgs()
+             << "execute-ptu "
+             << ((std::find(PTUs.begin(), PTUs.end(), T) != PTUs.end())
+                     ? std::distance(PTUs.begin(),
+                                     std::find(PTUs.begin(), PTUs.end(), T))
+                     : -1)
+             << ": [TU=" << T.TUPart << ", M=" << T.TheModule.get() << " ("
+             << T.TheModule->getName() << ")]\n");
   if (!IncrExecutor) {
     auto Err = CreateExecutor();
     if (Err)
@@ -723,10 +736,12 @@ std::unique_ptr<llvm::Module> Interpreter::GenModule() {
     // of the module which does not map well to CodeGen's design. To work this
     // around we created an empty module to make CodeGen happy. We should make
     // sure it always stays empty.
-    assert((!CachedInCodeGenModule || (CachedInCodeGenModule->empty() &&
-                                       CachedInCodeGenModule->global_empty() &&
-                                       CachedInCodeGenModule->alias_empty() &&
-                                       CachedInCodeGenModule->ifunc_empty())) &&
+    assert(((!CachedInCodeGenModule ||
+             !getCompilerInstance()->getPreprocessorOpts().Includes.empty()) ||
+            (CachedInCodeGenModule->empty() &&
+             CachedInCodeGenModule->global_empty() &&
+             CachedInCodeGenModule->alias_empty() &&
+             CachedInCodeGenModule->ifunc_empty())) &&
            "CodeGen wrote to a readonly module");
     std::unique_ptr<llvm::Module> M(CG->ReleaseModule());
     CG->StartModule("incr_module_" + std::to_string(ID++), M->getContext());