[Templight] Template Instantiation Observer

This patch adds a base-class called TemplateInstantiationObserver which gets
notified whenever a template instantiation is entered or exited during
semantic analysis. This is a base class used to implement the template
profiling and debugging tool called
Templight (https://github.com/mikael-s-persson/templight).

The patch also makes a few more changes:

* ActiveTemplateInstantiation class is moved out of the Sema class (so it can be used with inclusion of Sema.h).
* CreateFrontendAction function in front-end utilities is given external linkage (not longer a hidden static function).
* TemplateInstObserverChain data member added to Sema class to hold the list of template-inst observers.
* Notifications to the template-inst observer are added at the key places where templates are instantiated.

Patch by: Abel Sinkovics!

Differential Revision: https://reviews.llvm.org/D5767

llvm-svn: 324808

clang/include/clang/Driver/CC1Options.td

@@ -533,6 +533,8 @@ def ast_dump : Flag<["-"], "ast-dump">,
   HelpText<"Build ASTs and then debug dump them">;
 def ast_dump_all : Flag<["-"], "ast-dump-all">,
   HelpText<"Build ASTs and then debug dump them, forcing deserialization">;
+def templight_dump : Flag<["-"], "templight-dump">,
+  HelpText<"Dump templight information to stdout">;
 def ast_dump_lookups : Flag<["-"], "ast-dump-lookups">,
   HelpText<"Build ASTs and then debug dump their name lookup tables">;
 def ast_view : Flag<["-"], "ast-view">,

clang/include/clang/Frontend/FrontendActions.h

@@ -167,6 +167,14 @@ class VerifyPCHAction : public ASTFrontendAction {
   bool hasCodeCompletionSupport() const override { return false; }
 };
 
+class TemplightDumpAction : public ASTFrontendAction {
+protected:
+  std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI,
+                                                 StringRef InFile) override;
+
+  void ExecuteAction() override;
+};
+
 /**
  * \brief Frontend action adaptor that merges ASTs together.
  *

clang/include/clang/Frontend/FrontendOptions.h

@@ -58,6 +58,7 @@ namespace frontend {
     RewriteObjC,            ///< ObjC->C Rewriter.
     RewriteTest,            ///< Rewriter playground
     RunAnalysis,            ///< Run one or more source code analyses.
+    TemplightDump,          ///< Dump template instantiations
     MigrateSource,          ///< Run migrator.
     RunPreprocessorOnly     ///< Just lex, no output.
   };

clang/include/clang/FrontendTool/Utils.h

@@ -15,9 +15,18 @@
 #ifndef LLVM_CLANG_FRONTENDTOOL_UTILS_H
 #define LLVM_CLANG_FRONTENDTOOL_UTILS_H
 
+#include <memory>
+
 namespace clang {
 
 class CompilerInstance;
+class FrontendAction;
+
+/// Construct the FrontendAction of a compiler invocation based on the
+/// options specified for the compiler invocation.
+///
+/// \return - The created FrontendAction object
+std::unique_ptr<FrontendAction> CreateFrontendAction(CompilerInstance &CI);
 
 /// ExecuteCompilerInvocation - Execute the given actions described by the
 /// compiler invocation object in the given compiler instance.

clang/include/clang/Sema/Sema.h

@@ -172,6 +172,7 @@ namespace clang {
   class TemplateArgumentList;
   class TemplateArgumentLoc;
   class TemplateDecl;
+  class TemplateInstantiationCallback;
   class TemplateParameterList;
   class TemplatePartialOrderingContext;
   class TemplateTemplateParmDecl;
@@ -7127,6 +7128,12 @@ class Sema {
       /// We are defining a synthesized function (such as a defaulted special
       /// member).
       DefiningSynthesizedFunction,
+
+      /// Added for Template instantiation observation.
+      /// Memoization means we are _not_ instantiating a template because
+      /// it is already instantiated (but we entered a context where we
+      /// would have had to if it was not already instantiated).
+      Memoization
     } Kind;
 
     /// \brief Was the enclosing context a non-instantiation SFINAE context?
@@ -7235,6 +7242,14 @@ class Sema {
   // FIXME: Does this belong in Sema? It's tough to implement it anywhere else.
   unsigned LastEmittedCodeSynthesisContextDepth = 0;
 
+  /// \brief The template instantiation callbacks to trace or track
+  /// instantiations (objects can be chained).
+  ///
+  /// This callbacks is used to print, trace or track template
+  /// instantiations as they are being constructed.
+  std::vector<std::unique_ptr<TemplateInstantiationCallback>>
+      TemplateInstCallbacks;
+
   /// \brief The current index into pack expansion arguments that will be
   /// used for substitution of parameter packs.
   ///

clang/include/clang/Sema/TemplateInstCallback.h

@@ -0,0 +1,83 @@
+//===- TemplateInstCallback.h - Template Instantiation Callback - C++ --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===---------------------------------------------------------------------===//
+//
+// This file defines the TemplateInstantiationCallback class, which is the
+// base class for callbacks that will be notified at template instantiations.
+//
+//===---------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TEMPLATE_INST_CALLBACK_H
+#define LLVM_CLANG_TEMPLATE_INST_CALLBACK_H
+
+#include "clang/Sema/Sema.h"
+
+namespace clang {
+
+/// \brief This is a base class for callbacks that will be notified at every
+/// template instantiation.
+class TemplateInstantiationCallback {
+public:
+  virtual ~TemplateInstantiationCallback() = default;
+
+  /// \brief Called before doing AST-parsing.
+  virtual void initialize(const Sema &TheSema) = 0;
+
+  /// \brief Called after AST-parsing is completed.
+  virtual void finalize(const Sema &TheSema) = 0;
+
+  /// \brief Called when instantiation of a template just began.
+  virtual void atTemplateBegin(const Sema &TheSema,
+                               const Sema::CodeSynthesisContext &Inst) = 0;
+
+  /// \brief Called when instantiation of a template is just about to end.
+  virtual void atTemplateEnd(const Sema &TheSema,
+                             const Sema::CodeSynthesisContext &Inst) = 0;
+};
+
+template <class TemplateInstantiationCallbackPtrs>
+void initialize(TemplateInstantiationCallbackPtrs &Callbacks,
+                const Sema &TheSema) {
+  for (auto &C : Callbacks) {
+    if (C)
+      C->initialize(TheSema);
+  }
+}
+
+template <class TemplateInstantiationCallbackPtrs>
+void finalize(TemplateInstantiationCallbackPtrs &Callbacks,
+              const Sema &TheSema) {
+  for (auto &C : Callbacks) {
+    if (C)
+      C->finalize(TheSema);
+  }
+}
+
+template <class TemplateInstantiationCallbackPtrs>
+void atTemplateBegin(TemplateInstantiationCallbackPtrs &Callbacks,
+                     const Sema &TheSema,
+                     const Sema::CodeSynthesisContext &Inst) {
+  for (auto &C : Callbacks) {
+    if (C)
+      C->atTemplateBegin(TheSema, Inst);
+  }
+}
+
+template <class TemplateInstantiationCallbackPtrs>
+void atTemplateEnd(TemplateInstantiationCallbackPtrs &Callbacks,
+                   const Sema &TheSema,
+                   const Sema::CodeSynthesisContext &Inst) {
+  for (auto &C : Callbacks) {
+    if (C)
+      C->atTemplateEnd(TheSema, Inst);
+  }
+}
+
+} // namespace clang
+
+#endif

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1358,6 +1358,8 @@ static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
       Opts.ProgramAction = frontend::PrintPreamble; break;
     case OPT_E:
       Opts.ProgramAction = frontend::PrintPreprocessedInput; break;
+    case OPT_templight_dump:
+      Opts.ProgramAction = frontend::TemplightDump; break;
     case OPT_rewrite_macros:
       Opts.ProgramAction = frontend::RewriteMacros; break;
     case OPT_rewrite_objc:
@@ -2620,6 +2622,7 @@ static bool isStrictlyPreprocessorAction(frontend::ActionKind Action) {
   case frontend::RewriteObjC:
   case frontend::RewriteTest:
   case frontend::RunAnalysis:
+  case frontend::TemplightDump:
   case frontend::MigrateSource:
     return false;
 

clang/lib/Frontend/FrontendActions.cpp

@@ -18,17 +18,36 @@
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Lex/PreprocessorOptions.h"
+#include "clang/Sema/TemplateInstCallback.h"
 #include "clang/Serialization/ASTReader.h"
 #include "clang/Serialization/ASTWriter.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/YAMLTraits.h"
 #include <memory>
 #include <system_error>
 
 using namespace clang;
 
+namespace {
+CodeCompleteConsumer *GetCodeCompletionConsumer(CompilerInstance &CI) {
+  return CI.hasCodeCompletionConsumer() ? &CI.getCodeCompletionConsumer()
+                                        : nullptr;
+}
+
+void EnsureSemaIsCreated(CompilerInstance &CI, FrontendAction &Action) {
+  if (Action.hasCodeCompletionSupport() &&
+      !CI.getFrontendOpts().CodeCompletionAt.FileName.empty())
+    CI.createCodeCompletionConsumer();
+
+  if (!CI.hasSema())
+    CI.createSema(Action.getTranslationUnitKind(),
+                  GetCodeCompletionConsumer(CI));
+}
+} // namespace
+
 //===----------------------------------------------------------------------===//
 // Custom Actions
 //===----------------------------------------------------------------------===//
@@ -261,6 +280,140 @@ void VerifyPCHAction::ExecuteAction() {
                   ASTReader::ARR_ConfigurationMismatch);
 }
 
+namespace {
+struct TemplightEntry {
+  std::string Name;
+  std::string Kind;
+  std::string Event;
+  std::string DefinitionLocation;
+  std::string PointOfInstantiation;
+};
+} // namespace
+
+namespace llvm {
+namespace yaml {
+template <> struct MappingTraits<TemplightEntry> {
+  static void mapping(IO &io, TemplightEntry &fields) {
+    io.mapRequired("name", fields.Name);
+    io.mapRequired("kind", fields.Kind);
+    io.mapRequired("event", fields.Event);
+    io.mapRequired("orig", fields.DefinitionLocation);
+    io.mapRequired("poi", fields.PointOfInstantiation);
+  }
+};
+} // namespace yaml
+} // namespace llvm
+
+namespace {
+class DefaultTemplateInstCallback : public TemplateInstantiationCallback {
+  using CodeSynthesisContext = Sema::CodeSynthesisContext;
+
+public:
+  virtual void initialize(const Sema &) {}
+
+  virtual void finalize(const Sema &) {}
+
+  virtual void atTemplateBegin(const Sema &TheSema,
+                               const CodeSynthesisContext &Inst) override {
+    displayTemplightEntry<true>(llvm::outs(), TheSema, Inst);
+  }
+
+  virtual void atTemplateEnd(const Sema &TheSema,
+                             const CodeSynthesisContext &Inst) override {
+    displayTemplightEntry<false>(llvm::outs(), TheSema, Inst);
+  }
+
+private:
+  static std::string toString(CodeSynthesisContext::SynthesisKind Kind) {
+    switch (Kind) {
+    case CodeSynthesisContext::TemplateInstantiation:
+      return "TemplateInstantiation";
+    case CodeSynthesisContext::DefaultTemplateArgumentInstantiation:
+      return "DefaultTemplateArgumentInstantiation";
+    case CodeSynthesisContext::DefaultFunctionArgumentInstantiation:
+      return "DefaultFunctionArgumentInstantiation";
+    case CodeSynthesisContext::ExplicitTemplateArgumentSubstitution:
+      return "ExplicitTemplateArgumentSubstitution";
+    case CodeSynthesisContext::DeducedTemplateArgumentSubstitution:
+      return "DeducedTemplateArgumentSubstitution";
+    case CodeSynthesisContext::PriorTemplateArgumentSubstitution:
+      return "PriorTemplateArgumentSubstitution";
+    case CodeSynthesisContext::DefaultTemplateArgumentChecking:
+      return "DefaultTemplateArgumentChecking";
+    case CodeSynthesisContext::ExceptionSpecInstantiation:
+      return "ExceptionSpecInstantiation";
+    case CodeSynthesisContext::DeclaringSpecialMember:
+      return "DeclaringSpecialMember";
+    case CodeSynthesisContext::DefiningSynthesizedFunction:
+      return "DefiningSynthesizedFunction";
+    case CodeSynthesisContext::Memoization:
+      return "Memoization";
+    }
+    return "";
+  }
+
+  template <bool BeginInstantiation>
+  static void displayTemplightEntry(llvm::raw_ostream &Out, const Sema &TheSema,
+                                    const CodeSynthesisContext &Inst) {
+    std::string YAML;
+    {
+      llvm::raw_string_ostream OS(YAML);
+      llvm::yaml::Output YO(OS);
+      TemplightEntry Entry =
+          getTemplightEntry<BeginInstantiation>(TheSema, Inst);
+      llvm::yaml::EmptyContext Context;
+      llvm::yaml::yamlize(YO, Entry, true, Context);
+    }
+    Out << "---" << YAML << "\n";
+  }
+
+  template <bool BeginInstantiation>
+  static TemplightEntry getTemplightEntry(const Sema &TheSema,
+                                          const CodeSynthesisContext &Inst) {
+    TemplightEntry Entry;
+    Entry.Kind = toString(Inst.Kind);
+    Entry.Event = BeginInstantiation ? "Begin" : "End";
+    if (auto *NamedTemplate = dyn_cast_or_null<NamedDecl>(Inst.Entity)) {
+      llvm::raw_string_ostream OS(Entry.Name);
+      NamedTemplate->getNameForDiagnostic(OS, TheSema.getLangOpts(), true);
+      const PresumedLoc DefLoc = 
+        TheSema.getSourceManager().getPresumedLoc(Inst.Entity->getLocation());
+      if(!DefLoc.isInvalid())
+        Entry.DefinitionLocation = std::string(DefLoc.getFilename()) + ":" +
+                                   std::to_string(DefLoc.getLine()) + ":" +
+                                   std::to_string(DefLoc.getColumn());
+    }
+    const PresumedLoc PoiLoc =
+        TheSema.getSourceManager().getPresumedLoc(Inst.PointOfInstantiation);
+    if (!PoiLoc.isInvalid()) {
+      Entry.PointOfInstantiation = std::string(PoiLoc.getFilename()) + ":" +
+                                   std::to_string(PoiLoc.getLine()) + ":" +
+                                   std::to_string(PoiLoc.getColumn());
+    }
+    return Entry;
+  }
+};
+} // namespace
+
+std::unique_ptr<ASTConsumer>
+TemplightDumpAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
+  return llvm::make_unique<ASTConsumer>();
+}
+
+void TemplightDumpAction::ExecuteAction() {
+  CompilerInstance &CI = getCompilerInstance();
+
+  // This part is normally done by ASTFrontEndAction, but needs to happen
+  // before Templight observers can be created
+  // FIXME: Move the truncation aspect of this into Sema, we delayed this till
+  // here so the source manager would be initialized.
+  EnsureSemaIsCreated(CI, *this);
+
+  CI.getSema().TemplateInstCallbacks.push_back(
+      llvm::make_unique<DefaultTemplateInstCallback>());
+  ASTFrontendAction::ExecuteAction();
+}
+
 namespace {
   /// \brief AST reader listener that dumps module information for a module
   /// file.