tools/clang/blink_gc_plugin/BlinkGCPlugin.cpp

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
IsTemplateInstantiation
record_decls
trace_decls
shouldVisitTemplateInstantiations
VisitCXXRecordDecl
TraverseCXXMethodDecl
might_be_collected
VisitMember
VisitCollection
cache_
finalized_fields
WalkUpFromCXXOperatorCallExpr
WalkUpFromCallExpr
VisitMemberExpr
MightBeCollected
dispatched_to_receiver_
dispatched_to_receiver
VisitMemberExpr
info_
VisitMemberExpr
info_
IsWeakCallback
MarkTraced
gc_roots
ContainsGCRoots
VisitValue
VisitPersistent
AtCollection
stack_allocated_host_
invalid_fields
ContainsInvalidFields
VisitMember
VisitValue
json_
HandleTranslationUnit
CheckRecord
CheckClass
CheckDispatch
CheckFinalization
CheckTracingMethod
CheckTraceOrDispatchMethod
CheckTraceMethod
DumpClass
DumpEdge
DumpField
AtValue
getErrorLevel
GetLocString
IsIgnored
IsIgnoredClass
InIgnoredDirectory
InCheckedNamespace
GetFilename
ReportClassRequiresTraceMethod
ReportBaseRequiresTracing
ReportFieldsRequireTracing
ReportClassContainsInvalidFields
ReportClassContainsGCRoots
ReportFinalizerAccessesFinalizedFields
ReportClassRequiresFinalization
ReportOverriddenNonVirtualTrace
ReportMissingTraceDispatchMethod
ReportMissingFinalizeDispatchMethod
ReportMissingDispatchMethod
ReportVirtualAndManualDispatch
ReportMissingTraceDispatch
ReportMissingFinalizeDispatch
ReportMissingDispatch
ReportDerivesNonStackAllocated
NoteManualDispatchMethod
NoteFieldRequiresTracing
NotePartObjectContainsGCRoot
NoteFieldContainsGCRoot
NoteUserDeclaredDestructor
NoteUserDeclaredFinalizer
NoteBaseRequiresFinalization
NoteField
NoteField
NoteOverriddenNonVirtualTrace
CreateASTConsumer
ParseArgs
// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This clang plugin checks various invariants of the Blink garbage
// collection infrastructure.
//
// Errors are described at:
// http://www.chromium.org/developers/blink-gc-plugin-errors

#include "Config.h"
#include "JsonWriter.h"
#include "RecordInfo.h"

#include "clang/AST/AST.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Frontend/FrontendPluginRegistry.h"

using namespace clang;
using std::string;

namespace {

const char kClassRequiresTraceMethod[] =
    "[blink-gc] Class %0 requires a trace method"
    " because it contains fields that require tracing.";

const char kBaseRequiresTracing[] =
    "[blink-gc] Base class %0 of derived class %1 requires tracing.";

const char kFieldsRequireTracing[] =
    "[blink-gc] Class %0 has untraced fields that require tracing.";

const char kFieldRequiresTracingNote[] =
    "[blink-gc] Untraced field %0 declared here:";

const char kClassContainsInvalidFields[] =
    "[blink-gc] Class %0 contains invalid fields.";

const char kClassContainsGCRoot[] =
    "[blink-gc] Class %0 contains GC root in field %1.";

const char kClassRequiresFinalization[] =
    "[blink-gc] Class %0 requires finalization.";

const char kFinalizerAccessesFinalizedField[] =
    "[blink-gc] Finalizer %0 accesses potentially finalized field %1.";

const char kRawPtrToGCManagedClassNote[] =
    "[blink-gc] Raw pointer field %0 to a GC managed class declared here:";

const char kRefPtrToGCManagedClassNote[] =
    "[blink-gc] RefPtr field %0 to a GC managed class declared here:";

const char kOwnPtrToGCManagedClassNote[] =
    "[blink-gc] OwnPtr field %0 to a GC managed class declared here:";

const char kStackAllocatedFieldNote[] =
    "[blink-gc] Stack-allocated field %0 declared here:";

const char kMemberInUnmanagedClassNote[] =
    "[blink-gc] Member field %0 in unmanaged class declared here:";

const char kPartObjectContainsGCRoot[] =
    "[blink-gc] Field %0 with embedded GC root in %1 declared here:";

const char kFieldContainsGCRoot[] =
    "[blink-gc] Field %0 defining a GC root declared here:";

const char kOverriddenNonVirtualTrace[] =
    "[blink-gc] Class %0 overrides non-virtual trace of base class %1.";

const char kOverriddenNonVirtualTraceNote[] =
    "[blink-gc] Non-virtual trace method declared here:";

const char kMissingTraceDispatchMethod[] =
    "[blink-gc] Class %0 is missing manual trace dispatch.";

const char kMissingFinalizeDispatchMethod[] =
    "[blink-gc] Class %0 is missing manual finalize dispatch.";

const char kVirtualAndManualDispatch[] =
    "[blink-gc] Class %0 contains or inherits virtual methods"
    " but implements manual dispatching.";

const char kMissingTraceDispatch[] =
    "[blink-gc] Missing dispatch to class %0 in manual trace dispatch.";

const char kMissingFinalizeDispatch[] =
    "[blink-gc] Missing dispatch to class %0 in manual finalize dispatch.";

const char kFinalizedFieldNote[] =
    "[blink-gc] Potentially finalized field %0 declared here:";

const char kUserDeclaredDestructorNote[] =
    "[blink-gc] User-declared destructor declared here:";

const char kUserDeclaredFinalizerNote[] =
    "[blink-gc] User-declared finalizer declared here:";

const char kBaseRequiresFinalizationNote[] =
    "[blink-gc] Base class %0 requiring finalization declared here:";

const char kFieldRequiresFinalizationNote[] =
    "[blink-gc] Field %0 requiring finalization declared here:";

const char kManualDispatchMethodNote[] =
    "[blink-gc] Manual dispatch %0 declared here:";

const char kDerivesNonStackAllocated[] =
    "[blink-gc] Stack-allocated class %0 derives class %1"
    " which is not stack allocated.";

struct BlinkGCPluginOptions {
  BlinkGCPluginOptions() : enable_oilpan(false), dump_graph(false) {}
  bool enable_oilpan;
  bool dump_graph;
  std::set<std::string> ignored_classes;
  std::set<std::string> checked_namespaces;
  std::vector<std::string> ignored_directories;
};

typedef std::vector<CXXRecordDecl*> RecordVector;
typedef std::vector<CXXMethodDecl*> MethodVector;

// Test if a template specialization is an instantiation.
static bool IsTemplateInstantiation(CXXRecordDecl* record) {
  ClassTemplateSpecializationDecl* spec =
      dyn_cast<ClassTemplateSpecializationDecl>(record);
  if (!spec)
    return false;
  switch (spec->getTemplateSpecializationKind()) {
    case TSK_ImplicitInstantiation:
    case TSK_ExplicitInstantiationDefinition:
      return true;
    case TSK_Undeclared:
    case TSK_ExplicitSpecialization:
      return false;
    // TODO: unsupported cases.
    case TSK_ExplicitInstantiationDeclaration:
      return false;
  }
  assert(false && "Unknown template specialization kind");
}

// This visitor collects the entry points for the checker.
class CollectVisitor : public RecursiveASTVisitor<CollectVisitor> {
 public:
  CollectVisitor() {}

  RecordVector& record_decls() { return record_decls_; }
  MethodVector& trace_decls() { return trace_decls_; }

  bool shouldVisitTemplateInstantiations() { return false; }

  // Collect record declarations, including nested declarations.
  bool VisitCXXRecordDecl(CXXRecordDecl* record) {
    if (record->hasDefinition() && record->isCompleteDefinition())
      record_decls_.push_back(record);
    return true;
  }

  // Collect tracing method definitions, but don't traverse method bodies.
  bool TraverseCXXMethodDecl(CXXMethodDecl* method) {
    if (method->isThisDeclarationADefinition() && Config::IsTraceMethod(method))
      trace_decls_.push_back(method);
    return true;
  }

 private:
  RecordVector record_decls_;
  MethodVector trace_decls_;
};

// This visitor checks that a finalizer method does not have invalid access to
// fields that are potentially finalized. A potentially finalized field is
// either a Member, a heap-allocated collection or an off-heap collection that
// contains Members.  Invalid uses are currently identified as passing the field
// as the argument of a procedure call or using the -> or [] operators on it.
class CheckFinalizerVisitor
    : public RecursiveASTVisitor<CheckFinalizerVisitor> {
 private:
  // Simple visitor to determine if the content of a field might be collected
  // during finalization.
  class MightBeCollectedVisitor : public EdgeVisitor {
   public:
    MightBeCollectedVisitor() : might_be_collected_(false) {}
    bool might_be_collected() { return might_be_collected_; }
    void VisitMember(Member* edge) override { might_be_collected_ = true; }
    void VisitCollection(Collection* edge) override {
      if (edge->on_heap()) {
        might_be_collected_ = !edge->is_root();
      } else {
        edge->AcceptMembers(this);
      }
    }

   private:
    bool might_be_collected_;
  };

 public:
  typedef std::vector<std::pair<MemberExpr*, FieldPoint*> > Errors;

  CheckFinalizerVisitor(RecordCache* cache)
      : blacklist_context_(false), cache_(cache) {}

  Errors& finalized_fields() { return finalized_fields_; }

  bool WalkUpFromCXXOperatorCallExpr(CXXOperatorCallExpr* expr) {
    // Only continue the walk-up if the operator is a blacklisted one.
    switch (expr->getOperator()) {
      case OO_Arrow:
      case OO_Subscript:
        this->WalkUpFromCallExpr(expr);
      default:
        return true;
    }
  }

  // We consider all non-operator calls to be blacklisted contexts.
  bool WalkUpFromCallExpr(CallExpr* expr) {
    bool prev_blacklist_context = blacklist_context_;
    blacklist_context_ = true;
    for (size_t i = 0; i < expr->getNumArgs(); ++i)
      this->TraverseStmt(expr->getArg(i));
    blacklist_context_ = prev_blacklist_context;
    return true;
  }

  bool VisitMemberExpr(MemberExpr* member) {
    FieldDecl* field = dyn_cast<FieldDecl>(member->getMemberDecl());
    if (!field)
      return true;

    RecordInfo* info = cache_->Lookup(field->getParent());
    if (!info)
      return true;

    RecordInfo::Fields::iterator it = info->GetFields().find(field);
    if (it == info->GetFields().end())
      return true;

    if (blacklist_context_ && MightBeCollected(&it->second))
      finalized_fields_.push_back(std::make_pair(member, &it->second));
    return true;
  }

  bool MightBeCollected(FieldPoint* point) {
    MightBeCollectedVisitor visitor;
    point->edge()->Accept(&visitor);
    return visitor.might_be_collected();
  }

 private:
  bool blacklist_context_;
  Errors finalized_fields_;
  RecordCache* cache_;
};

// This visitor checks that a method contains within its body, a call to a
// method on the provided receiver class. This is used to check manual
// dispatching for trace and finalize methods.
class CheckDispatchVisitor : public RecursiveASTVisitor<CheckDispatchVisitor> {
 public:
  CheckDispatchVisitor(RecordInfo* receiver)
      : receiver_(receiver), dispatched_to_receiver_(false) {}

  bool dispatched_to_receiver() { return dispatched_to_receiver_; }

  bool VisitMemberExpr(MemberExpr* member) {
    if (CXXMethodDecl* fn = dyn_cast<CXXMethodDecl>(member->getMemberDecl())) {
      if (fn->getParent() == receiver_->record())
        dispatched_to_receiver_ = true;
    }
    return true;
  }

 private:
  RecordInfo* receiver_;
  bool dispatched_to_receiver_;
};

// This visitor checks a tracing method by traversing its body.
// - A member field is considered traced if it is referenced in the body.
// - A base is traced if a base-qualified call to a trace method is found.
class CheckTraceVisitor : public RecursiveASTVisitor<CheckTraceVisitor> {
 public:
  CheckTraceVisitor(CXXMethodDecl* trace, RecordInfo* info)
      : trace_(trace), info_(info) {}

  // Allow recursive traversal by using VisitMemberExpr.
  bool VisitMemberExpr(MemberExpr* member) {
    // If this member expression references a field decl, mark it as traced.
    if (FieldDecl* field = dyn_cast<FieldDecl>(member->getMemberDecl())) {
      if (IsTemplateInstantiation(info_->record())) {
        // Pointer equality on fields does not work for template instantiations.
        // The trace method refers to fields of the template definition which
        // are different from the instantiated fields that need to be traced.
        const string& name = field->getNameAsString();
        for (RecordInfo::Fields::iterator it = info_->GetFields().begin();
             it != info_->GetFields().end();
             ++it) {
          if (it->first->getNameAsString() == name) {
            MarkTraced(it);
            break;
          }
        }
      } else {
        RecordInfo::Fields::iterator it = info_->GetFields().find(field);
        if (it != info_->GetFields().end())
          MarkTraced(it);
      }
      return true;
    }

    // If this is a weak callback function we only check field tracing.
    if (IsWeakCallback())
      return true;

    // For method calls, check tracing of bases and other special GC methods.
    if (CXXMethodDecl* fn = dyn_cast<CXXMethodDecl>(member->getMemberDecl())) {
      const string& name = fn->getNameAsString();
      // Check weak callbacks.
      if (name == kRegisterWeakMembersName) {
        if (fn->isTemplateInstantiation()) {
          const TemplateArgumentList& args =
              *fn->getTemplateSpecializationInfo()->TemplateArguments;
          // The second template argument is the callback method.
          if (args.size() > 1 &&
              args[1].getKind() == TemplateArgument::Declaration) {
            if (FunctionDecl* callback =
                    dyn_cast<FunctionDecl>(args[1].getAsDecl())) {
              if (callback->hasBody()) {
                CheckTraceVisitor nested_visitor(info_);
                nested_visitor.TraverseStmt(callback->getBody());
              }
            }
          }
        }
        return true;
      }

      // TODO: It is possible to have multiple bases, where one must be traced
      // using a traceAfterDispatch. In such a case we should also check that
      // the mixin does not add a vtable.
      if (Config::IsTraceMethod(fn) && member->hasQualifier()) {
        if (const Type* type = member->getQualifier()->getAsType()) {
          if (CXXRecordDecl* decl = type->getAsCXXRecordDecl()) {
            RecordInfo::Bases::iterator it = info_->GetBases().find(decl);
            if (it != info_->GetBases().end())
              it->second.MarkTraced();
          }
        }
      }
    }
    return true;
  }

 private:
  // Nested checking for weak callbacks.
  CheckTraceVisitor(RecordInfo* info) : trace_(0), info_(info) {}

  bool IsWeakCallback() { return !trace_; }

  void MarkTraced(RecordInfo::Fields::iterator it) {
    // In a weak callback we can't mark strong fields as traced.
    if (IsWeakCallback() && !it->second.edge()->IsWeakMember())
      return;
    it->second.MarkTraced();
  }

  CXXMethodDecl* trace_;
  RecordInfo* info_;
};

// This visitor checks that the fields of a class and the fields of
// its part objects don't define GC roots.
class CheckGCRootsVisitor : public RecursiveEdgeVisitor {
 public:
  typedef std::vector<FieldPoint*> RootPath;
  typedef std::vector<RootPath> Errors;

  CheckGCRootsVisitor() {}

  Errors& gc_roots() { return gc_roots_; }

  bool ContainsGCRoots(RecordInfo* info) {
    for (RecordInfo::Fields::iterator it = info->GetFields().begin();
         it != info->GetFields().end();
         ++it) {
      current_.push_back(&it->second);
      it->second.edge()->Accept(this);
      current_.pop_back();
    }
    return !gc_roots_.empty();
  }

  void VisitValue(Value* edge) override {
    // TODO: what should we do to check unions?
    if (edge->value()->record()->isUnion())
      return;

    // If the value is a part object, then continue checking for roots.
    for (Context::iterator it = context().begin();
         it != context().end();
         ++it) {
      if (!(*it)->IsCollection())
        return;
    }
    ContainsGCRoots(edge->value());
  }

  void VisitPersistent(Persistent* edge) override {
    gc_roots_.push_back(current_);
  }

  void AtCollection(Collection* edge) override {
    if (edge->is_root())
      gc_roots_.push_back(current_);
  }

 protected:
  RootPath current_;
  Errors gc_roots_;
};

// This visitor checks that the fields of a class are "well formed".
// - OwnPtr, RefPtr and RawPtr must not point to a GC derived types.
// - An on-heap class must never contain GC roots.
class CheckFieldsVisitor : public RecursiveEdgeVisitor {
 public:
  typedef std::vector<std::pair<FieldPoint*, Edge*> > Errors;

  CheckFieldsVisitor(const BlinkGCPluginOptions& options)
      : options_(options), current_(0), stack_allocated_host_(false) {}

  Errors& invalid_fields() { return invalid_fields_; }

  bool ContainsInvalidFields(RecordInfo* info) {
    stack_allocated_host_ = info->IsStackAllocated();
    managed_host_ = stack_allocated_host_ ||
                    info->IsGCAllocated() ||
                    info->IsNonNewable() ||
                    info->IsOnlyPlacementNewable();
    for (RecordInfo::Fields::iterator it = info->GetFields().begin();
         it != info->GetFields().end();
         ++it) {
      context().clear();
      current_ = &it->second;
      current_->edge()->Accept(this);
    }
    return !invalid_fields_.empty();
  }

  void VisitMember(Member* edge) override {
    if (managed_host_)
      return;
    // A member is allowed to appear in the context of a root.
    for (Context::iterator it = context().begin();
         it != context().end();
         ++it) {
      if ((*it)->Kind() == Edge::kRoot)
        return;
    }
    invalid_fields_.push_back(std::make_pair(current_, edge));
  }

  void VisitValue(Value* edge) override {
    // TODO: what should we do to check unions?
    if (edge->value()->record()->isUnion())
      return;

    if (!stack_allocated_host_ && edge->value()->IsStackAllocated()) {
      invalid_fields_.push_back(std::make_pair(current_, edge));
      return;
    }

    if (!Parent() || !edge->value()->IsGCAllocated())
      return;

    if (Parent()->IsOwnPtr() ||
        (stack_allocated_host_ && Parent()->IsRawPtr() &&
         // TODO: Remove this exception once the node hierarchy is moved.
         !edge->value()->IsTreeShared())) {
      invalid_fields_.push_back(std::make_pair(current_, Parent()));
      return;
    }

    // Don't check raw and ref pointers in transition mode.
    if (options_.enable_oilpan)
      return;

    if (Parent()->IsRawPtr() || Parent()->IsRefPtr())
      invalid_fields_.push_back(std::make_pair(current_, Parent()));
  }

 private:
  const BlinkGCPluginOptions& options_;
  FieldPoint* current_;
  bool stack_allocated_host_;
  bool managed_host_;
  Errors invalid_fields_;
};

// Main class containing checks for various invariants of the Blink
// garbage collection infrastructure.
class BlinkGCPluginConsumer : public ASTConsumer {
 public:
  BlinkGCPluginConsumer(CompilerInstance& instance,
                        const BlinkGCPluginOptions& options)
      : instance_(instance),
        diagnostic_(instance.getDiagnostics()),
        options_(options),
        json_(0) {

    // Only check structures in the blink, WebCore and WebKit namespaces.
    options_.checked_namespaces.insert("blink");
    options_.checked_namespaces.insert("WebCore");
    options_.checked_namespaces.insert("WebKit");

    // Ignore GC implementation files.
    options_.ignored_directories.push_back("/heap/");

    // Register warning/error messages.
    diag_class_requires_trace_method_ =
        diagnostic_.getCustomDiagID(getErrorLevel(), kClassRequiresTraceMethod);
    diag_base_requires_tracing_ =
        diagnostic_.getCustomDiagID(getErrorLevel(), kBaseRequiresTracing);
    diag_fields_require_tracing_ =
        diagnostic_.getCustomDiagID(getErrorLevel(), kFieldsRequireTracing);
    diag_class_contains_invalid_fields_ = diagnostic_.getCustomDiagID(
        getErrorLevel(), kClassContainsInvalidFields);
    diag_class_contains_gc_root_ =
        diagnostic_.getCustomDiagID(getErrorLevel(), kClassContainsGCRoot);
    diag_class_requires_finalization_ = diagnostic_.getCustomDiagID(
        getErrorLevel(), kClassRequiresFinalization);
    diag_finalizer_accesses_finalized_field_ = diagnostic_.getCustomDiagID(
        getErrorLevel(), kFinalizerAccessesFinalizedField);
    diag_overridden_non_virtual_trace_ = diagnostic_.getCustomDiagID(
        getErrorLevel(), kOverriddenNonVirtualTrace);
    diag_missing_trace_dispatch_method_ = diagnostic_.getCustomDiagID(
        getErrorLevel(), kMissingTraceDispatchMethod);
    diag_missing_finalize_dispatch_method_ = diagnostic_.getCustomDiagID(
        getErrorLevel(), kMissingFinalizeDispatchMethod);
    diag_virtual_and_manual_dispatch_ =
        diagnostic_.getCustomDiagID(getErrorLevel(), kVirtualAndManualDispatch);
    diag_missing_trace_dispatch_ =
        diagnostic_.getCustomDiagID(getErrorLevel(), kMissingTraceDispatch);
    diag_missing_finalize_dispatch_ =
        diagnostic_.getCustomDiagID(getErrorLevel(), kMissingFinalizeDispatch);
    diag_derives_non_stack_allocated_ =
        diagnostic_.getCustomDiagID(getErrorLevel(), kDerivesNonStackAllocated);

    // Register note messages.
    diag_field_requires_tracing_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kFieldRequiresTracingNote);
    diag_raw_ptr_to_gc_managed_class_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kRawPtrToGCManagedClassNote);
    diag_ref_ptr_to_gc_managed_class_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kRefPtrToGCManagedClassNote);
    diag_own_ptr_to_gc_managed_class_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kOwnPtrToGCManagedClassNote);
    diag_stack_allocated_field_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kStackAllocatedFieldNote);
    diag_member_in_unmanaged_class_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kMemberInUnmanagedClassNote);
    diag_part_object_contains_gc_root_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kPartObjectContainsGCRoot);
    diag_field_contains_gc_root_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kFieldContainsGCRoot);
    diag_finalized_field_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kFinalizedFieldNote);
    diag_user_declared_destructor_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kUserDeclaredDestructorNote);
    diag_user_declared_finalizer_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kUserDeclaredFinalizerNote);
    diag_base_requires_finalization_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kBaseRequiresFinalizationNote);
    diag_field_requires_finalization_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kFieldRequiresFinalizationNote);
    diag_overridden_non_virtual_trace_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kOverriddenNonVirtualTraceNote);
    diag_manual_dispatch_method_note_ = diagnostic_.getCustomDiagID(
        DiagnosticsEngine::Note, kManualDispatchMethodNote);
  }

  void HandleTranslationUnit(ASTContext& context) override {
    CollectVisitor visitor;
    visitor.TraverseDecl(context.getTranslationUnitDecl());

    if (options_.dump_graph) {
      string err;
      // TODO: Make createDefaultOutputFile or a shorter createOutputFile work.
      json_ = JsonWriter::from(instance_.createOutputFile(
          "",                                      // OutputPath
          err,                                     // Errors
          true,                                    // Binary
          true,                                    // RemoveFileOnSignal
          instance_.getFrontendOpts().OutputFile,  // BaseInput
          "graph.json",                            // Extension
          false,                                   // UseTemporary
          false,                                   // CreateMissingDirectories
          0,                                       // ResultPathName
          0));                                     // TempPathName
      if (err.empty() && json_) {
        json_->OpenList();
      } else {
        json_ = 0;
        llvm::errs()
            << "[blink-gc] "
            << "Failed to create an output file for the object graph.\n";
      }
    }

    for (RecordVector::iterator it = visitor.record_decls().begin();
         it != visitor.record_decls().end();
         ++it) {
      CheckRecord(cache_.Lookup(*it));
    }

    for (MethodVector::iterator it = visitor.trace_decls().begin();
         it != visitor.trace_decls().end();
         ++it) {
      CheckTracingMethod(*it);
    }

    if (json_) {
      json_->CloseList();
      delete json_;
      json_ = 0;
    }
  }

  // Main entry for checking a record declaration.
  void CheckRecord(RecordInfo* info) {
    if (IsIgnored(info))
      return;

    CXXRecordDecl* record = info->record();

    // TODO: what should we do to check unions?
    if (record->isUnion())
      return;

    // If this is the primary template declaration, check its specializations.
    if (record->isThisDeclarationADefinition() &&
        record->getDescribedClassTemplate()) {
      ClassTemplateDecl* tmpl = record->getDescribedClassTemplate();
      for (ClassTemplateDecl::spec_iterator it = tmpl->spec_begin();
           it != tmpl->spec_end();
           ++it) {
        CheckClass(cache_.Lookup(*it));
      }
      return;
    }

    CheckClass(info);
  }

  // Check a class-like object (eg, class, specialization, instantiation).
  void CheckClass(RecordInfo* info) {
    if (!info)
      return;

    // Check consistency of stack-allocated hierarchies.
    if (info->IsStackAllocated()) {
      for (RecordInfo::Bases::iterator it = info->GetBases().begin();
           it != info->GetBases().end();
           ++it) {
        if (!it->second.info()->IsStackAllocated())
          ReportDerivesNonStackAllocated(info, &it->second);
      }
    }

    if (info->RequiresTraceMethod() && !info->GetTraceMethod())
      ReportClassRequiresTraceMethod(info);

    {
      CheckFieldsVisitor visitor(options_);
      if (visitor.ContainsInvalidFields(info))
        ReportClassContainsInvalidFields(info, &visitor.invalid_fields());
    }

    if (info->IsGCDerived()) {
      CheckDispatch(info);

      // TODO: Remove this exception once TreeShared is properly traced.
      if (!info->IsTreeShared()) {
        CheckGCRootsVisitor visitor;
        if (visitor.ContainsGCRoots(info))
          ReportClassContainsGCRoots(info, &visitor.gc_roots());
      }

      if (info->NeedsFinalization())
        CheckFinalization(info);
    }

    DumpClass(info);
  }

  void CheckDispatch(RecordInfo* info) {
    bool finalized = info->IsGCFinalized();
    CXXMethodDecl* trace_dispatch = info->GetTraceDispatchMethod();
    CXXMethodDecl* finalize_dispatch = info->GetFinalizeDispatchMethod();
    if (!trace_dispatch && !finalize_dispatch)
      return;

    CXXRecordDecl* base = trace_dispatch ? trace_dispatch->getParent()
                                         : finalize_dispatch->getParent();

    // Check that dispatch methods are defined at the base.
    if (base == info->record()) {
      if (!trace_dispatch)
        ReportMissingTraceDispatchMethod(info);
      if (finalized && !finalize_dispatch)
        ReportMissingFinalizeDispatchMethod(info);
      if (!finalized && finalize_dispatch) {
        ReportClassRequiresFinalization(info);
        NoteUserDeclaredFinalizer(finalize_dispatch);
      }
    }

    // Check that classes implementing manual dispatch do not have vtables.
    if (info->record()->isPolymorphic())
      ReportVirtualAndManualDispatch(
          info, trace_dispatch ? trace_dispatch : finalize_dispatch);

    // If this is a non-abstract class check that it is dispatched to.
    // TODO: Create a global variant of this local check. We can only check if
    // the dispatch body is known in this compilation unit.
    if (info->IsConsideredAbstract())
      return;

    const FunctionDecl* defn;

    if (trace_dispatch && trace_dispatch->isDefined(defn)) {
      CheckDispatchVisitor visitor(info);
      visitor.TraverseStmt(defn->getBody());
      if (!visitor.dispatched_to_receiver())
        ReportMissingTraceDispatch(defn, info);
    }

    if (finalized && finalize_dispatch && finalize_dispatch->isDefined(defn)) {
      CheckDispatchVisitor visitor(info);
      visitor.TraverseStmt(defn->getBody());
      if (!visitor.dispatched_to_receiver())
        ReportMissingFinalizeDispatch(defn, info);
    }
  }

  // TODO: Should we collect destructors similar to trace methods?
  void CheckFinalization(RecordInfo* info) {
    CXXDestructorDecl* dtor = info->record()->getDestructor();

    // For finalized classes, check the finalization method if possible.
    if (info->IsGCFinalized()) {
      if (dtor && dtor->hasBody()) {
        CheckFinalizerVisitor visitor(&cache_);
        visitor.TraverseCXXMethodDecl(dtor);
        if (!visitor.finalized_fields().empty()) {
          ReportFinalizerAccessesFinalizedFields(
              dtor, &visitor.finalized_fields());
        }
      }
      return;
    }

    // Don't require finalization of a mixin that has not yet been "mixed in".
    if (info->IsGCMixin())
      return;

    // Report the finalization error, and proceed to print possible causes for
    // the finalization requirement.
    ReportClassRequiresFinalization(info);

    if (dtor && dtor->isUserProvided())
      NoteUserDeclaredDestructor(dtor);

    for (RecordInfo::Bases::iterator it = info->GetBases().begin();
         it != info->GetBases().end();
         ++it) {
      if (it->second.info()->NeedsFinalization())
        NoteBaseRequiresFinalization(&it->second);
    }

    for (RecordInfo::Fields::iterator it = info->GetFields().begin();
         it != info->GetFields().end();
         ++it) {
      if (it->second.edge()->NeedsFinalization())
        NoteField(&it->second, diag_field_requires_finalization_note_);
    }
  }

  // This is the main entry for tracing method definitions.
  void CheckTracingMethod(CXXMethodDecl* method) {
    RecordInfo* parent = cache_.Lookup(method->getParent());
    if (IsIgnored(parent))
      return;

    // Check templated tracing methods by checking the template instantiations.
    // Specialized templates are handled as ordinary classes.
    if (ClassTemplateDecl* tmpl =
            parent->record()->getDescribedClassTemplate()) {
      for (ClassTemplateDecl::spec_iterator it = tmpl->spec_begin();
           it != tmpl->spec_end();
           ++it) {
        // Check trace using each template instantiation as the holder.
        if (IsTemplateInstantiation(*it))
          CheckTraceOrDispatchMethod(cache_.Lookup(*it), method);
      }
      return;
    }

    CheckTraceOrDispatchMethod(parent, method);
  }

  // Determine what type of tracing method this is (dispatch or trace).
  void CheckTraceOrDispatchMethod(RecordInfo* parent, CXXMethodDecl* method) {
    bool isTraceAfterDispatch;
    if (Config::IsTraceMethod(method, &isTraceAfterDispatch)) {
      if (isTraceAfterDispatch || !parent->GetTraceDispatchMethod()) {
        CheckTraceMethod(parent, method, isTraceAfterDispatch);
      }
      // Dispatch methods are checked when we identify subclasses.
    }
  }

  // Check an actual trace method.
  void CheckTraceMethod(RecordInfo* parent,
                        CXXMethodDecl* trace,
                        bool isTraceAfterDispatch) {
    // A non-virtual trace method must not override another trace.
    if (!isTraceAfterDispatch && !trace->isVirtual()) {
      for (RecordInfo::Bases::iterator it = parent->GetBases().begin();
           it != parent->GetBases().end();
           ++it) {
        RecordInfo* base = it->second.info();
        // We allow mixin bases to contain a non-virtual trace since it will
        // never be used for dispatching.
        if (base->IsGCMixin())
          continue;
        if (CXXMethodDecl* other = base->InheritsNonVirtualTrace())
          ReportOverriddenNonVirtualTrace(parent, trace, other);
      }
    }

    CheckTraceVisitor visitor(trace, parent);
    visitor.TraverseCXXMethodDecl(trace);

    for (RecordInfo::Bases::iterator it = parent->GetBases().begin();
         it != parent->GetBases().end();
         ++it) {
      if (!it->second.IsProperlyTraced())
        ReportBaseRequiresTracing(parent, trace, it->first);
    }

    for (RecordInfo::Fields::iterator it = parent->GetFields().begin();
         it != parent->GetFields().end();
         ++it) {
      if (!it->second.IsProperlyTraced()) {
        // Discontinue once an untraced-field error is found.
        ReportFieldsRequireTracing(parent, trace);
        break;
      }
    }
  }

  void DumpClass(RecordInfo* info) {
    if (!json_)
      return;

    json_->OpenObject();
    json_->Write("name", info->record()->getQualifiedNameAsString());
    json_->Write("loc", GetLocString(info->record()->getLocStart()));
    json_->CloseObject();

    class DumpEdgeVisitor : public RecursiveEdgeVisitor {
     public:
      DumpEdgeVisitor(JsonWriter* json) : json_(json) {}
      void DumpEdge(RecordInfo* src,
                    RecordInfo* dst,
                    const string& lbl,
                    const Edge::LivenessKind& kind,
                    const string& loc) {
        json_->OpenObject();
        json_->Write("src", src->record()->getQualifiedNameAsString());
        json_->Write("dst", dst->record()->getQualifiedNameAsString());
        json_->Write("lbl", lbl);
        json_->Write("kind", kind);
        json_->Write("loc", loc);
        json_->Write("ptr",
                     !Parent() ? "val" :
                     Parent()->IsRawPtr() ? "raw" :
                     Parent()->IsRefPtr() ? "ref" :
                     Parent()->IsOwnPtr() ? "own" :
                     (Parent()->IsMember() ||
                      Parent()->IsWeakMember()) ? "mem" :
                     "val");
        json_->CloseObject();
      }

      void DumpField(RecordInfo* src, FieldPoint* point, const string& loc) {
        src_ = src;
        point_ = point;
        loc_ = loc;
        point_->edge()->Accept(this);
      }

      void AtValue(Value* e) override {
        // The liveness kind of a path from the point to this value
        // is given by the innermost place that is non-strong.
        Edge::LivenessKind kind = Edge::kStrong;
        if (Config::IsIgnoreCycleAnnotated(point_->field())) {
          kind = Edge::kWeak;
        } else {
          for (Context::iterator it = context().begin();
               it != context().end();
               ++it) {
            Edge::LivenessKind pointer_kind = (*it)->Kind();
            if (pointer_kind != Edge::kStrong) {
              kind = pointer_kind;
              break;
            }
          }
        }
        DumpEdge(
            src_, e->value(), point_->field()->getNameAsString(), kind, loc_);
      }

     private:
      JsonWriter* json_;
      RecordInfo* src_;
      FieldPoint* point_;
      string loc_;
    };

    DumpEdgeVisitor visitor(json_);

    RecordInfo::Bases& bases = info->GetBases();
    for (RecordInfo::Bases::iterator it = bases.begin();
         it != bases.end();
         ++it) {
      visitor.DumpEdge(info,
                       it->second.info(),
                       "<super>",
                       Edge::kStrong,
                       GetLocString(it->second.spec().getLocStart()));
    }

    RecordInfo::Fields& fields = info->GetFields();
    for (RecordInfo::Fields::iterator it = fields.begin();
         it != fields.end();
         ++it) {
      visitor.DumpField(info,
                        &it->second,
                        GetLocString(it->second.field()->getLocStart()));
    }
  }

  // Adds either a warning or error, based on the current handling of -Werror.
  DiagnosticsEngine::Level getErrorLevel() {
    return diagnostic_.getWarningsAsErrors() ? DiagnosticsEngine::Error
                                             : DiagnosticsEngine::Warning;
  }

  const string GetLocString(SourceLocation loc) {
    const SourceManager& source_manager = instance_.getSourceManager();
    PresumedLoc ploc = source_manager.getPresumedLoc(loc);
    if (ploc.isInvalid())
      return "";
    string loc_str;
    llvm::raw_string_ostream OS(loc_str);
    OS << ploc.getFilename()
       << ":" << ploc.getLine()
       << ":" << ploc.getColumn();
    return OS.str();
  }

  bool IsIgnored(RecordInfo* record) {
    return !record ||
           !InCheckedNamespace(record) ||
           IsIgnoredClass(record) ||
           InIgnoredDirectory(record);
  }

  bool IsIgnoredClass(RecordInfo* info) {
    // Ignore any class prefixed by SameSizeAs. These are used in
    // Blink to verify class sizes and don't need checking.
    const string SameSizeAs = "SameSizeAs";
    if (info->name().compare(0, SameSizeAs.size(), SameSizeAs) == 0)
      return true;
    return options_.ignored_classes.find(info->name()) !=
           options_.ignored_classes.end();
  }

  bool InIgnoredDirectory(RecordInfo* info) {
    string filename;
    if (!GetFilename(info->record()->getLocStart(), &filename))
      return false;  // TODO: should we ignore non-existing file locations?
    std::vector<string>::iterator it = options_.ignored_directories.begin();
    for (; it != options_.ignored_directories.end(); ++it)
      if (filename.find(*it) != string::npos)
        return true;
    return false;
  }

  bool InCheckedNamespace(RecordInfo* info) {
    if (!info)
      return false;
    DeclContext* context = info->record()->getDeclContext();
    if (context->isRecord())
      return InCheckedNamespace(cache_.Lookup(context));
    if (context->isNamespace()) {
      const NamespaceDecl* decl = dyn_cast<NamespaceDecl>(context);
      if (decl->isAnonymousNamespace())
        return false;
      return options_.checked_namespaces.find(decl->getNameAsString()) !=
          options_.checked_namespaces.end();
    }
    return false;
  }

  bool GetFilename(SourceLocation loc, string* filename) {
    const SourceManager& source_manager = instance_.getSourceManager();
    SourceLocation spelling_location = source_manager.getSpellingLoc(loc);
    PresumedLoc ploc = source_manager.getPresumedLoc(spelling_location);
    if (ploc.isInvalid()) {
      // If we're in an invalid location, we're looking at things that aren't
      // actually stated in the source.
      return false;
    }
    *filename = ploc.getFilename();
    return true;
  }

  void ReportClassRequiresTraceMethod(RecordInfo* info) {
    SourceLocation loc = info->record()->getInnerLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_class_requires_trace_method_)
        << info->record();
    for (RecordInfo::Fields::iterator it = info->GetFields().begin();
         it != info->GetFields().end();
         ++it) {
      if (!it->second.IsProperlyTraced())
        NoteFieldRequiresTracing(info, it->first);
    }
  }

  void ReportBaseRequiresTracing(RecordInfo* derived,
                                 CXXMethodDecl* trace,
                                 CXXRecordDecl* base) {
    SourceLocation loc = trace->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_base_requires_tracing_)
        << base << derived->record();
  }

  void ReportFieldsRequireTracing(RecordInfo* info, CXXMethodDecl* trace) {
    SourceLocation loc = trace->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_fields_require_tracing_)
        << info->record();
    for (RecordInfo::Fields::iterator it = info->GetFields().begin();
         it != info->GetFields().end();
         ++it) {
      if (!it->second.IsProperlyTraced())
        NoteFieldRequiresTracing(info, it->first);
    }
  }

  void ReportClassContainsInvalidFields(RecordInfo* info,
                                        CheckFieldsVisitor::Errors* errors) {
    SourceLocation loc = info->record()->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_class_contains_invalid_fields_)
        << info->record();
    for (CheckFieldsVisitor::Errors::iterator it = errors->begin();
         it != errors->end();
         ++it) {
      if (it->second->IsRawPtr()) {
        NoteField(it->first, diag_raw_ptr_to_gc_managed_class_note_);
      } else if (it->second->IsRefPtr()) {
        NoteField(it->first, diag_ref_ptr_to_gc_managed_class_note_);
      } else if (it->second->IsOwnPtr()) {
        NoteField(it->first, diag_own_ptr_to_gc_managed_class_note_);
      } else if (it->second->IsMember()) {
        NoteField(it->first, diag_member_in_unmanaged_class_note_);
      } else if (it->second->IsValue()) {
        NoteField(it->first, diag_stack_allocated_field_note_);
      }
    }
  }

  void ReportClassContainsGCRoots(RecordInfo* info,
                                  CheckGCRootsVisitor::Errors* errors) {
    SourceLocation loc = info->record()->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    for (CheckGCRootsVisitor::Errors::iterator it = errors->begin();
         it != errors->end();
         ++it) {
      CheckGCRootsVisitor::RootPath::iterator path = it->begin();
      FieldPoint* point = *path;
      diagnostic_.Report(full_loc, diag_class_contains_gc_root_)
          << info->record() << point->field();
      while (++path != it->end()) {
        NotePartObjectContainsGCRoot(point);
        point = *path;
      }
      NoteFieldContainsGCRoot(point);
    }
  }

  void ReportFinalizerAccessesFinalizedFields(
      CXXMethodDecl* dtor,
      CheckFinalizerVisitor::Errors* fields) {
    for (CheckFinalizerVisitor::Errors::iterator it = fields->begin();
         it != fields->end();
         ++it) {
      SourceLocation loc = it->first->getLocStart();
      SourceManager& manager = instance_.getSourceManager();
      FullSourceLoc full_loc(loc, manager);
      diagnostic_.Report(full_loc, diag_finalizer_accesses_finalized_field_)
          << dtor << it->second->field();
      NoteField(it->second, diag_finalized_field_note_);
    }
  }

  void ReportClassRequiresFinalization(RecordInfo* info) {
    SourceLocation loc = info->record()->getInnerLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_class_requires_finalization_)
        << info->record();
  }

  void ReportOverriddenNonVirtualTrace(RecordInfo* info,
                                       CXXMethodDecl* trace,
                                       CXXMethodDecl* overridden) {
    SourceLocation loc = trace->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_overridden_non_virtual_trace_)
        << info->record() << overridden->getParent();
    NoteOverriddenNonVirtualTrace(overridden);
  }

  void ReportMissingTraceDispatchMethod(RecordInfo* info) {
    ReportMissingDispatchMethod(info, diag_missing_trace_dispatch_method_);
  }

  void ReportMissingFinalizeDispatchMethod(RecordInfo* info) {
    ReportMissingDispatchMethod(info, diag_missing_finalize_dispatch_method_);
  }

  void ReportMissingDispatchMethod(RecordInfo* info, unsigned error) {
    SourceLocation loc = info->record()->getInnerLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, error) << info->record();
  }

  void ReportVirtualAndManualDispatch(RecordInfo* info,
                                      CXXMethodDecl* dispatch) {
    SourceLocation loc = info->record()->getInnerLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_virtual_and_manual_dispatch_)
        << info->record();
    NoteManualDispatchMethod(dispatch);
  }

  void ReportMissingTraceDispatch(const FunctionDecl* dispatch,
                                  RecordInfo* receiver) {
    ReportMissingDispatch(dispatch, receiver, diag_missing_trace_dispatch_);
  }

  void ReportMissingFinalizeDispatch(const FunctionDecl* dispatch,
                                     RecordInfo* receiver) {
    ReportMissingDispatch(dispatch, receiver, diag_missing_finalize_dispatch_);
  }

  void ReportMissingDispatch(const FunctionDecl* dispatch,
                             RecordInfo* receiver,
                             unsigned error) {
    SourceLocation loc = dispatch->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, error) << receiver->record();
  }

  void ReportDerivesNonStackAllocated(RecordInfo* info, BasePoint* base) {
    SourceLocation loc = base->spec().getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_derives_non_stack_allocated_)
        << info->record() << base->info()->record();
  }

  void NoteManualDispatchMethod(CXXMethodDecl* dispatch) {
    SourceLocation loc = dispatch->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_manual_dispatch_method_note_) << dispatch;
  }

  void NoteFieldRequiresTracing(RecordInfo* holder, FieldDecl* field) {
    NoteField(field, diag_field_requires_tracing_note_);
  }

  void NotePartObjectContainsGCRoot(FieldPoint* point) {
    FieldDecl* field = point->field();
    SourceLocation loc = field->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_part_object_contains_gc_root_note_)
        << field << field->getParent();
  }

  void NoteFieldContainsGCRoot(FieldPoint* point) {
    NoteField(point, diag_field_contains_gc_root_note_);
  }

  void NoteUserDeclaredDestructor(CXXMethodDecl* dtor) {
    SourceLocation loc = dtor->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_user_declared_destructor_note_);
  }

  void NoteUserDeclaredFinalizer(CXXMethodDecl* dtor) {
    SourceLocation loc = dtor->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_user_declared_finalizer_note_);
  }

  void NoteBaseRequiresFinalization(BasePoint* base) {
    SourceLocation loc = base->spec().getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_base_requires_finalization_note_)
        << base->info()->record();
  }

  void NoteField(FieldPoint* point, unsigned note) {
    NoteField(point->field(), note);
  }

  void NoteField(FieldDecl* field, unsigned note) {
    SourceLocation loc = field->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, note) << field;
  }

  void NoteOverriddenNonVirtualTrace(CXXMethodDecl* overridden) {
    SourceLocation loc = overridden->getLocStart();
    SourceManager& manager = instance_.getSourceManager();
    FullSourceLoc full_loc(loc, manager);
    diagnostic_.Report(full_loc, diag_overridden_non_virtual_trace_note_)
        << overridden;
  }

  unsigned diag_class_requires_trace_method_;
  unsigned diag_base_requires_tracing_;
  unsigned diag_fields_require_tracing_;
  unsigned diag_class_contains_invalid_fields_;
  unsigned diag_class_contains_gc_root_;
  unsigned diag_class_requires_finalization_;
  unsigned diag_finalizer_accesses_finalized_field_;
  unsigned diag_overridden_non_virtual_trace_;
  unsigned diag_missing_trace_dispatch_method_;
  unsigned diag_missing_finalize_dispatch_method_;
  unsigned diag_virtual_and_manual_dispatch_;
  unsigned diag_missing_trace_dispatch_;
  unsigned diag_missing_finalize_dispatch_;
  unsigned diag_derives_non_stack_allocated_;

  unsigned diag_field_requires_tracing_note_;
  unsigned diag_raw_ptr_to_gc_managed_class_note_;
  unsigned diag_ref_ptr_to_gc_managed_class_note_;
  unsigned diag_own_ptr_to_gc_managed_class_note_;
  unsigned diag_stack_allocated_field_note_;
  unsigned diag_member_in_unmanaged_class_note_;
  unsigned diag_part_object_contains_gc_root_note_;
  unsigned diag_field_contains_gc_root_note_;
  unsigned diag_finalized_field_note_;
  unsigned diag_user_declared_destructor_note_;
  unsigned diag_user_declared_finalizer_note_;
  unsigned diag_base_requires_finalization_note_;
  unsigned diag_field_requires_finalization_note_;
  unsigned diag_overridden_non_virtual_trace_note_;
  unsigned diag_manual_dispatch_method_note_;

  CompilerInstance& instance_;
  DiagnosticsEngine& diagnostic_;
  BlinkGCPluginOptions options_;
  RecordCache cache_;
  JsonWriter* json_;
};

class BlinkGCPluginAction : public PluginASTAction {
 public:
  BlinkGCPluginAction() {}

 protected:
  // Overridden from PluginASTAction:
  virtual ASTConsumer* CreateASTConsumer(CompilerInstance& instance,
                                         llvm::StringRef ref) {
    return new BlinkGCPluginConsumer(instance, options_);
  }

  virtual bool ParseArgs(const CompilerInstance& instance,
                         const std::vector<string>& args) {
    bool parsed = true;

    for (size_t i = 0; i < args.size() && parsed; ++i) {
      if (args[i] == "enable-oilpan") {
        options_.enable_oilpan = true;
      } else if (args[i] == "dump-graph") {
        options_.dump_graph = true;
      } else {
        parsed = false;
        llvm::errs() << "Unknown blink-gc-plugin argument: " << args[i] << "\n";
      }
    }

    return parsed;
  }

 private:
  BlinkGCPluginOptions options_;
};

}  // namespace

static FrontendPluginRegistry::Add<BlinkGCPluginAction> X(
    "blink-gc-plugin",
    "Check Blink GC invariants");
/* [<][>][^][v][top][bottom][index][help] */
root/tools/clang/blink_gc_plugin/BlinkGCPlugin.cpp

DEFINITIONS
