[clang-repl] Lay the basic infrastructure for pretty printing of types (#148701)

The idea is to store a type-value pair in clang::Value which is updated
by the interpreter runtime. The class copies builtin types and boxes
non-builtin types to provide some lifetime control.

The patch enables default printers for C and C++ using a very
minimalistic approach. We handle enums, arrays and user types. Once we
land this we can focus on enabling user-defined pretty-printers which
take control over printing of types

The work started as part of https://reviews.llvm.org/D146809, then we
created a giant in #84769

Author: vgvassilev

clang/include/clang/AST/ASTContext.h

@@ -1192,6 +1192,8 @@ class ASTContext : public RefCountedBase<ASTContext> {
   bool isInSameModule(const Module *M1, const Module *M2) const;
 
   TranslationUnitDecl *getTranslationUnitDecl() const {
+    assert(TUDecl->getMostRecentDecl() == TUDecl &&
+           "The active TU is not current one!");
     return TUDecl->getMostRecentDecl();
   }
   void addTranslationUnitDecl() {

clang/include/clang/Interpreter/Interpreter.h

@@ -175,31 +175,42 @@ class Interpreter {
   llvm::Expected<llvm::orc::ExecutorAddr>
   getSymbolAddressFromLinkerName(llvm::StringRef LinkerName) const;
 
-  const llvm::SmallVectorImpl<Expr *> &getValuePrintingInfo() const {
-    return ValuePrintingInfo;
-  }
-
-  Expr *SynthesizeExpr(Expr *E);
+  std::unique_ptr<llvm::Module> GenModule(IncrementalAction *Action = nullptr);
+  PartialTranslationUnit &RegisterPTU(TranslationUnitDecl *TU,
+                                      std::unique_ptr<llvm::Module> M = {},
+                                      IncrementalAction *Action = nullptr);
 
 private:
   size_t getEffectivePTUSize() const;
   void markUserCodeStart();
   llvm::Expected<Expr *> ExtractValueFromExpr(Expr *E);
-  llvm::Expected<llvm::orc::ExecutorAddr> CompileDtorCall(CXXRecordDecl *CXXRD);
-
-  CodeGenerator *getCodeGen(IncrementalAction *Action = nullptr) const;
-  std::unique_ptr<llvm::Module> GenModule(IncrementalAction *Action = nullptr);
-  PartialTranslationUnit &RegisterPTU(TranslationUnitDecl *TU,
-                                      std::unique_ptr<llvm::Module> M = {},
-                                      IncrementalAction *Action = nullptr);
 
   // A cache for the compiled destructors used to for de-allocation of managed
   // clang::Values.
-  llvm::DenseMap<CXXRecordDecl *, llvm::orc::ExecutorAddr> Dtors;
+  mutable llvm::DenseMap<CXXRecordDecl *, llvm::orc::ExecutorAddr> Dtors;
 
-  llvm::SmallVector<Expr *, 4> ValuePrintingInfo;
+  std::array<Expr *, 4> ValuePrintingInfo = {0};
 
   std::unique_ptr<llvm::orc::LLJITBuilder> JITBuilder;
+
+  /// @}
+  /// @name Value and pretty printing support
+  /// @{
+
+  std::string ValueDataToString(const Value &V) const;
+  std::string ValueTypeToString(const Value &V) const;
+
+  llvm::Expected<Expr *> convertExprToValue(Expr *E);
+
+  // When we deallocate clang::Value we need to run the destructor of the type.
+  // This function forces emission of the needed dtor.
+  llvm::Expected<llvm::orc::ExecutorAddr>
+  CompileDtorCall(CXXRecordDecl *CXXRD) const;
+
+  /// @}
+  /// @name Code generation
+  /// @{
+  CodeGenerator *getCodeGen(IncrementalAction *Action = nullptr) const;
 };
 } // namespace clang
 

clang/include/clang/Interpreter/Value.h

@@ -35,6 +35,7 @@
 
 #include "llvm/Config/llvm-config.h" // for LLVM_BUILD_LLVM_DYLIB, LLVM_BUILD_SHARED_LIBS
 #include "llvm/Support/Compiler.h"
+#include <cassert>
 #include <cstdint>
 
 // NOTE: Since the REPL itself could also include this runtime, extreme caution
@@ -97,6 +98,7 @@ class REPL_EXTERNAL_VISIBILITY Value {
     REPL_BUILTIN_TYPES
 #undef X
     void *m_Ptr;
+    unsigned char m_RawBits[sizeof(long double) * 8]; // widest type
   };
 
 public:
@@ -111,7 +113,7 @@ class REPL_EXTERNAL_VISIBILITY Value {
   };
 
   Value() = default;
-  Value(Interpreter *In, void *Ty);
+  Value(const Interpreter *In, void *Ty);
   Value(const Value &RHS);
   Value(Value &&RHS) noexcept;
   Value &operator=(const Value &RHS);
@@ -124,9 +126,7 @@ class REPL_EXTERNAL_VISIBILITY Value {
   void dump() const;
   void clear();
 
-  ASTContext &getASTContext();
   const ASTContext &getASTContext() const;
-  Interpreter &getInterpreter();
   const Interpreter &getInterpreter() const;
   QualType getType() const;
 
@@ -140,6 +140,7 @@ class REPL_EXTERNAL_VISIBILITY Value {
 
   void *getPtr() const;
   void setPtr(void *Ptr) { Data.m_Ptr = Ptr; }
+  void setRawBits(void *Ptr, unsigned NBits = sizeof(Storage));
 
 #define X(type, name)                                                          \
   void set##name(type Val) { Data.m_##name = Val; }                            \
@@ -193,7 +194,7 @@ class REPL_EXTERNAL_VISIBILITY Value {
     }
   };
 
-  Interpreter *Interp = nullptr;
+  const Interpreter *Interp = nullptr;
   void *OpaqueType = nullptr;
   Storage Data;
   Kind ValueKind = K_Unspecified;
@@ -205,6 +206,5 @@ template <> inline void *Value::as() const {
     return Data.m_Ptr;
   return (void *)as<uintptr_t>();
 }
-
 } // namespace clang
 #endif

clang/lib/Interpreter/CMakeLists.txt

@@ -29,6 +29,7 @@ add_clang_library(clangInterpreter
   InterpreterUtils.cpp
   RemoteJITUtils.cpp
   Value.cpp
+  InterpreterValuePrinter.cpp
   ${WASM_SRC}
   PARTIAL_SOURCES_INTENDED
 

clang/lib/Interpreter/Interpreter.cpp

@@ -264,7 +264,7 @@ class InProcessPrintingASTConsumer final : public MultiplexConsumer {
       if (auto *TLSD = llvm::dyn_cast<TopLevelStmtDecl>(D))
         if (TLSD && TLSD->isSemiMissing()) {
           auto ExprOrErr =
-              Interp.ExtractValueFromExpr(cast<Expr>(TLSD->getStmt()));
+              Interp.convertExprToValue(cast<Expr>(TLSD->getStmt()));
           if (llvm::Error E = ExprOrErr.takeError()) {
             llvm::logAllUnhandledErrors(std::move(E), llvm::errs(),
                                         "Value printing failed: ");
@@ -440,11 +440,10 @@ const char *const Runtimes = R"(
     #define __CLANG_REPL__ 1
 #ifdef __cplusplus
     #define EXTERN_C extern "C"
-    void *__clang_Interpreter_SetValueWithAlloc(void*, void*, void*);
     struct __clang_Interpreter_NewTag{} __ci_newtag;
     void* operator new(__SIZE_TYPE__, void* __p, __clang_Interpreter_NewTag) noexcept;
     template <class T, class = T (*)() /*disable for arrays*/>
-    void __clang_Interpreter_SetValueCopyArr(T* Src, void* Placement, unsigned long Size) {
+    void __clang_Interpreter_SetValueCopyArr(const T* Src, void* Placement, unsigned long Size) {
       for (auto Idx = 0; Idx < Size; ++Idx)
         new ((void*)(((T*)Placement) + Idx), __ci_newtag) T(Src[Idx]);
     }
@@ -454,8 +453,12 @@ const char *const Runtimes = R"(
     }
 #else
     #define EXTERN_C extern
+    EXTERN_C void *memcpy(void *restrict dst, const void *restrict src, __SIZE_TYPE__ n);
+    EXTERN_C inline void __clang_Interpreter_SetValueCopyArr(const void* Src, void* Placement, unsigned long Size) {
+      memcpy(Placement, Src, Size);
+    }
 #endif // __cplusplus
-
+  EXTERN_C void *__clang_Interpreter_SetValueWithAlloc(void*, void*, void*);
   EXTERN_C void __clang_Interpreter_SetValueNoAlloc(void *This, void *OutVal, void *OpaqueType, ...);
 )";
 
@@ -470,12 +473,12 @@ Interpreter::create(std::unique_ptr<CompilerInstance> CI,
 
   // Add runtime code and set a marker to hide it from user code. Undo will not
   // go through that.
-  auto PTU = Interp->Parse(Runtimes);
-  if (!PTU)
-    return PTU.takeError();
+  Err = Interp->ParseAndExecute(Runtimes);
+  if (Err)
+    return std::move(Err);
+
   Interp->markUserCodeStart();
 
-  Interp->ValuePrintingInfo.resize(4);
   return std::move(Interp);
 }
 
@@ -524,12 +527,11 @@ Interpreter::createWithCUDA(std::unique_ptr<CompilerInstance> CI,
   return std::move(Interp);
 }
 
+CompilerInstance *Interpreter::getCompilerInstance() { return CI.get(); }
 const CompilerInstance *Interpreter::getCompilerInstance() const {
-  return CI.get();
+  return const_cast<Interpreter *>(this)->getCompilerInstance();
 }
 
-CompilerInstance *Interpreter::getCompilerInstance() { return CI.get(); }
-
 llvm::Expected<llvm::orc::LLJIT &> Interpreter::getExecutionEngine() {
   if (!IncrExecutor) {
     if (auto Err = CreateExecutor())
@@ -610,7 +612,14 @@ Interpreter::Parse(llvm::StringRef Code) {
   if (!TuOrErr)
     return TuOrErr.takeError();
 
-  return RegisterPTU(*TuOrErr);
+  PTUs.emplace_back(PartialTranslationUnit());
+  PartialTranslationUnit &LastPTU = PTUs.back();
+  LastPTU.TUPart = *TuOrErr;
+
+  if (std::unique_ptr<llvm::Module> M = GenModule())
+    LastPTU.TheModule = std::move(M);
+
+  return LastPTU;
 }
 
 static llvm::Expected<llvm::orc::JITTargetMachineBuilder>
@@ -808,10 +817,10 @@ Interpreter::GenModule(IncrementalAction *Action) {
     // sure it always stays empty.
     assert(((!CachedInCodeGenModule ||
              !getCompilerInstance()->getPreprocessorOpts().Includes.empty()) ||
-            (CachedInCodeGenModule->empty() &&
-             CachedInCodeGenModule->global_empty() &&
-             CachedInCodeGenModule->alias_empty() &&
-             CachedInCodeGenModule->ifunc_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());
@@ -828,4 +837,4 @@ CodeGenerator *Interpreter::getCodeGen(IncrementalAction *Action) const {
     return nullptr;
   return static_cast<CodeGenAction *>(WrappedAct)->getCodeGenerator();
 }
-} // namespace clang
+} // end namespace clang

clang/lib/Interpreter/InterpreterUtils.cpp

@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "InterpreterUtils.h"
+#include "clang/AST/QualTypeNames.h"
 
 namespace clang {
 
@@ -81,7 +82,7 @@ NamedDecl *LookupNamed(Sema &S, llvm::StringRef Name,
   else {
     const DeclContext *PrimaryWithin = nullptr;
     if (const auto *TD = dyn_cast<TagDecl>(Within))
-      PrimaryWithin = llvm::dyn_cast_or_null<DeclContext>(TD->getDefinition());
+      PrimaryWithin = dyn_cast_if_present<DeclContext>(TD->getDefinition());
     else
       PrimaryWithin = Within->getPrimaryContext();
 
@@ -97,15 +98,16 @@ NamedDecl *LookupNamed(Sema &S, llvm::StringRef Name,
   R.resolveKind();
 
   if (R.isSingleResult())
-    return llvm::dyn_cast<NamedDecl>(R.getFoundDecl());
+    return dyn_cast<NamedDecl>(R.getFoundDecl());
 
   return nullptr;
 }
 
 std::string GetFullTypeName(ASTContext &Ctx, QualType QT) {
+  QualType FQT = TypeName::getFullyQualifiedType(QT, Ctx);
   PrintingPolicy Policy(Ctx.getPrintingPolicy());
   Policy.SuppressScope = false;
   Policy.AnonymousTagLocations = false;
-  return QT.getAsString(Policy);
+  return FQT.getAsString(Policy);
 }
 } // namespace clang

clang/lib/Interpreter/InterpreterUtils.h

@@ -45,7 +45,7 @@ NamespaceDecl *LookupNamespace(Sema &S, llvm::StringRef Name,
                                const DeclContext *Within = nullptr);
 
 NamedDecl *LookupNamed(Sema &S, llvm::StringRef Name,
-                       const DeclContext *Within);
+                       const DeclContext *Within = nullptr);
 
 std::string GetFullTypeName(ASTContext &Ctx, QualType QT);
 } // namespace clang