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// Copyright 2011 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// This is clang plugin used by gcmole tool. See README for more details.

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#include <bitset>
#include <fstream>
#include <iostream>
#include <map>
#include <set>
#include <stack>

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#include "clang/AST/AST.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/Mangle.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/StmtVisitor.h"
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#include "clang/Basic/FileManager.h"
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#include "clang/Frontend/CompilerInstance.h"
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#include "clang/Frontend/FrontendPluginRegistry.h"
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#include "llvm/Support/raw_ostream.h"

namespace {

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bool g_tracing_enabled = false;
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bool g_dead_vars_analysis = false;
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#define TRACE(str)                   \
  do {                               \
    if (g_tracing_enabled) {         \
      std::cout << str << std::endl; \
    }                                \
  } while (false)

#define TRACE_LLVM_TYPE(str, type)                                \
  do {                                                            \
    if (g_tracing_enabled) {                                      \
      std::cout << str << " " << type.getAsString() << std::endl; \
    }                                                             \
  } while (false)

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// Node: The following is used when tracing --dead-vars
// to provide extra info for the GC suspect.
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#define TRACE_LLVM_DECL(str, decl)                   \
  do {                                               \
    if (g_tracing_enabled && g_dead_vars_analysis) { \
      std::cout << str << std::endl;                 \
      decl->dump();                                  \
    }                                                \
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  } while (false)

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typedef std::string MangledName;
typedef std::set<MangledName> CalleesSet;
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typedef std::map<MangledName, MangledName> CalleesMap;
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static bool GetMangledName(clang::MangleContext* ctx,
                           const clang::NamedDecl* decl,
                           MangledName* result) {
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  if (!llvm::isa<clang::CXXConstructorDecl>(decl) &&
      !llvm::isa<clang::CXXDestructorDecl>(decl)) {
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    llvm::SmallVector<char, 512> output;
    llvm::raw_svector_ostream out(output);
    ctx->mangleName(decl, out);
    *result = out.str().str();
    return true;
  }

  return false;
}


static bool InV8Namespace(const clang::NamedDecl* decl) {
  return decl->getQualifiedNameAsString().compare(0, 4, "v8::") == 0;
}


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static std::string EXTERNAL("EXTERNAL");
static std::string STATE_TAG("enum v8::internal::StateTag");

static bool IsExternalVMState(const clang::ValueDecl* var) {
  const clang::EnumConstantDecl* enum_constant =
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      llvm::dyn_cast<clang::EnumConstantDecl>(var);
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  if (enum_constant != NULL && enum_constant->getNameAsString() == EXTERNAL) {
    clang::QualType type = enum_constant->getType();
    return (type.getAsString() == STATE_TAG);
  }

  return false;
}


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struct Resolver {
  explicit Resolver(clang::ASTContext& ctx)
      : ctx_(ctx), decl_ctx_(ctx.getTranslationUnitDecl()) {
  }

  Resolver(clang::ASTContext& ctx, clang::DeclContext* decl_ctx)
      : ctx_(ctx), decl_ctx_(decl_ctx) {
  }

  clang::DeclarationName ResolveName(const char* n) {
    clang::IdentifierInfo* ident = &ctx_.Idents.get(n);
    return ctx_.DeclarationNames.getIdentifier(ident);
  }

  Resolver ResolveNamespace(const char* n) {
    return Resolver(ctx_, Resolve<clang::NamespaceDecl>(n));
  }

  template<typename T>
  T* Resolve(const char* n) {
    if (decl_ctx_ == NULL) return NULL;

    clang::DeclContext::lookup_result result =
        decl_ctx_->lookup(ResolveName(n));

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    clang::DeclContext::lookup_iterator end = result.end();
    for (clang::DeclContext::lookup_iterator i = result.begin(); i != end;
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         i++) {
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      if (llvm::isa<T>(*i)) {
        return llvm::cast<T>(*i);
      } else {
        llvm::errs() << "Didn't match declaration template against "
                     << (*i)->getNameAsString() << "\n";
      }
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    }

    return NULL;
  }

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  clang::CXXRecordDecl* ResolveTemplate(const char* n) {
    clang::NamedDecl* initial_template = Resolve<clang::NamedDecl>(n);
    if (!initial_template) return NULL;

    clang::NamedDecl* underlying_template =
        initial_template->getUnderlyingDecl();
    if (!underlying_template) {
      llvm::errs() << "Couldn't resolve underlying template\n";
      return NULL;
    }
    const clang::TypeAliasDecl* type_alias_decl =
        llvm::dyn_cast_or_null<clang::TypeAliasDecl>(underlying_template);
    if (!type_alias_decl) {
      llvm::errs() << "Couldn't resolve TypeAliasDecl\n";
      return NULL;
    }
    const clang::Type* type = type_alias_decl->getTypeForDecl();
    if (!type) {
      llvm::errs() << "Couldn't resolve TypeAliasDecl to Type\n";
      return NULL;
    }
    const clang::TypedefType* typedef_type =
        llvm::dyn_cast_or_null<clang::TypedefType>(type);
    if (!typedef_type) {
      llvm::errs() << "Couldn't resolve TypedefType\n";
      return NULL;
    }
    const clang::TypedefNameDecl* typedef_name_decl = typedef_type->getDecl();
    if (!typedef_name_decl) {
      llvm::errs() << "Couldn't resolve TypedefType to TypedefNameDecl\n";
      return NULL;
    }

    clang::QualType underlying_type = typedef_name_decl->getUnderlyingType();
    if (!llvm::isa<clang::TemplateSpecializationType>(underlying_type)) {
      llvm::errs() << "Couldn't resolve TemplateSpecializationType\n";
      return NULL;
    }

    const clang::TemplateSpecializationType* templ_specialization_type =
        llvm::cast<clang::TemplateSpecializationType>(underlying_type);
    if (!llvm::isa<clang::RecordType>(templ_specialization_type->desugar())) {
      llvm::errs() << "Couldn't resolve RecordType\n";
      return NULL;
    }

    const clang::RecordType* record_type =
        llvm::cast<clang::RecordType>(templ_specialization_type->desugar());
    clang::CXXRecordDecl* record_decl =
        llvm::dyn_cast_or_null<clang::CXXRecordDecl>(record_type->getDecl());
    if (!record_decl) {
      llvm::errs() << "Couldn't resolve CXXRecordDecl\n";
      return NULL;
    }
    return record_decl;
  }

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 private:
  clang::ASTContext& ctx_;
  clang::DeclContext* decl_ctx_;
};


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class CalleesPrinter : public clang::RecursiveASTVisitor<CalleesPrinter> {
 public:
  explicit CalleesPrinter(clang::MangleContext* ctx) : ctx_(ctx) {
  }

  virtual bool VisitCallExpr(clang::CallExpr* expr) {
    const clang::FunctionDecl* callee = expr->getDirectCallee();
    if (callee != NULL) AnalyzeFunction(callee);
    return true;
  }

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  virtual bool VisitDeclRefExpr(clang::DeclRefExpr* expr) {
    // If function mentions EXTERNAL VMState add artificial garbage collection
    // mark.
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    if (IsExternalVMState(expr->getDecl())) {
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      AddCallee("CollectGarbage", "CollectGarbage");
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    }
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    return true;
  }

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  void AnalyzeFunction(const clang::FunctionDecl* f) {
    MangledName name;
    if (InV8Namespace(f) && GetMangledName(ctx_, f, &name)) {
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      const std::string& function = f->getNameAsString();
      AddCallee(name, function);
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      const clang::FunctionDecl* body = NULL;
      if (f->hasBody(body) && !Analyzed(name)) {
        EnterScope(name);
        TraverseStmt(body->getBody());
        LeaveScope();
      }
    }
  }

  typedef std::map<MangledName, CalleesSet* > Callgraph;

  bool Analyzed(const MangledName& name) {
    return callgraph_[name] != NULL;
  }

  void EnterScope(const MangledName& name) {
    CalleesSet* callees = callgraph_[name];

    if (callees == NULL) {
      callgraph_[name] = callees = new CalleesSet();
    }

    scopes_.push(callees);
  }

  void LeaveScope() {
    scopes_.pop();
  }

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  void AddCallee(const MangledName& name, const MangledName& function) {
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    if (!scopes_.empty()) scopes_.top()->insert(name);
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    mangled_to_function_[name] = function;
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  }

  void PrintCallGraph() {
    for (Callgraph::const_iterator i = callgraph_.begin(), e = callgraph_.end();
         i != e;
         ++i) {
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      std::cout << i->first << "," << mangled_to_function_[i->first] << "\n";
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      CalleesSet* callees = i->second;
      for (CalleesSet::const_iterator j = callees->begin(), e = callees->end();
           j != e;
           ++j) {
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        std::cout << "\t" << *j << "," << mangled_to_function_[*j] << "\n";
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      }
    }
  }

 private:
  clang::MangleContext* ctx_;

  std::stack<CalleesSet* > scopes_;
  Callgraph callgraph_;
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  CalleesMap mangled_to_function_;
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};

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class FunctionDeclarationFinder
    : public clang::ASTConsumer,
      public clang::RecursiveASTVisitor<FunctionDeclarationFinder> {
 public:
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  explicit FunctionDeclarationFinder(clang::DiagnosticsEngine& d,
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                                     clang::SourceManager& sm,
                                     const std::vector<std::string>& args)
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      : d_(d), sm_(sm) {}
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  virtual void HandleTranslationUnit(clang::ASTContext &ctx) {
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    mangle_context_ = clang::ItaniumMangleContext::create(ctx, d_);
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    callees_printer_ = new CalleesPrinter(mangle_context_);

    TraverseDecl(ctx.getTranslationUnitDecl());

    callees_printer_->PrintCallGraph();
  }

  virtual bool VisitFunctionDecl(clang::FunctionDecl* decl) {
    callees_printer_->AnalyzeFunction(decl);
    return true;
  }

 private:
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  clang::DiagnosticsEngine& d_;
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  clang::SourceManager& sm_;
  clang::MangleContext* mangle_context_;

  CalleesPrinter* callees_printer_;
};

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static bool gc_suspects_loaded = false;
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static CalleesSet gc_suspects;
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static CalleesSet gc_functions;
static bool whitelist_loaded = false;
static CalleesSet suspects_whitelist;
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static void LoadGCSuspects() {
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  if (gc_suspects_loaded) return;
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  std::ifstream fin("gcsuspects");
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  std::string mangled, function;
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  while (!fin.eof()) {
    std::getline(fin, mangled, ',');
    gc_suspects.insert(mangled);
    std::getline(fin, function);
    gc_functions.insert(function);
  }
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  gc_suspects_loaded = true;
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}

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static void LoadSuspectsWhitelist() {
  if (whitelist_loaded) return;

  std::ifstream fin("tools/gcmole/suspects.whitelist");
  std::string s;

  while (fin >> s) suspects_whitelist.insert(s);
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  whitelist_loaded = true;
}

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// Looks for exact match of the mangled name.
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static bool KnownToCauseGC(clang::MangleContext* ctx,
                           const clang::FunctionDecl* decl) {
  LoadGCSuspects();

  if (!InV8Namespace(decl)) return false;

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  if (suspects_whitelist.find(decl->getNameAsString()) !=
      suspects_whitelist.end()) {
    return false;
  }

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  MangledName name;
  if (GetMangledName(ctx, decl, &name)) {
    return gc_suspects.find(name) != gc_suspects.end();
  }

  return false;
}

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// Looks for partial match of only the function name.
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static bool SuspectedToCauseGC(clang::MangleContext* ctx,
                               const clang::FunctionDecl* decl) {
  LoadGCSuspects();

  if (!InV8Namespace(decl)) return false;

  LoadSuspectsWhitelist();
  if (suspects_whitelist.find(decl->getNameAsString()) !=
      suspects_whitelist.end()) {
    return false;
  }

  if (gc_functions.find(decl->getNameAsString()) != gc_functions.end()) {
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    TRACE_LLVM_DECL("Suspected by ", decl);
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    return true;
  }

  return false;
}
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static const int kNoEffect = 0;
static const int kCausesGC = 1;
static const int kRawDef = 2;
static const int kRawUse = 4;
static const int kAllEffects = kCausesGC | kRawDef | kRawUse;
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class Environment;

class ExprEffect {
 public:
  bool hasGC() { return (effect_ & kCausesGC) != 0; }
  void setGC() { effect_ |= kCausesGC; }

  bool hasRawDef() { return (effect_ & kRawDef) != 0; }
  void setRawDef() { effect_ |= kRawDef; }

  bool hasRawUse() { return (effect_ & kRawUse) != 0; }
  void setRawUse() { effect_ |= kRawUse; }

  static ExprEffect None() { return ExprEffect(kNoEffect, NULL); }
  static ExprEffect NoneWithEnv(Environment* env) {
    return ExprEffect(kNoEffect, env);
  }
  static ExprEffect RawUse() { return ExprEffect(kRawUse, NULL); }

  static ExprEffect Merge(ExprEffect a, ExprEffect b);
  static ExprEffect MergeSeq(ExprEffect a, ExprEffect b);
  ExprEffect Define(const std::string& name);

  Environment* env() {
    return reinterpret_cast<Environment*>(effect_ & ~kAllEffects);
  }

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  static ExprEffect GC() {
    return ExprEffect(kCausesGC, NULL);
  }

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 private:
  ExprEffect(int effect, Environment* env)
      : effect_((effect & kAllEffects) |
                reinterpret_cast<intptr_t>(env)) { }

  intptr_t effect_;
};


const std::string BAD_EXPR_MSG("Possible problem with evaluation order.");
const std::string DEAD_VAR_MSG("Possibly dead variable.");


class Environment {
 public:
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  Environment() = default;
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  static Environment Unreachable() {
    Environment env;
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    env.unreachable_ = true;
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    return env;
  }

  static Environment Merge(const Environment& l,
                           const Environment& r) {
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    Environment out(l);
    out &= r;
    return out;
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  }

  Environment ApplyEffect(ExprEffect effect) const {
    Environment out = effect.hasGC() ? Environment() : Environment(*this);
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    if (effect.env()) out |= *effect.env();
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    return out;
  }

  typedef std::map<std::string, int> SymbolTable;

  bool IsAlive(const std::string& name) const {
    SymbolTable::iterator code = symbol_table_.find(name);
    if (code == symbol_table_.end()) return false;
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    return is_live(code->second);
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  }

  bool Equal(const Environment& env) {
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    if (unreachable_ && env.unreachable_) return true;
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    size_t size = std::max(live_.size(), env.live_.size());
    for (size_t i = 0; i < size; ++i) {
      if (is_live(i) != env.is_live(i)) return false;
    }
    return true;
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  }

  Environment Define(const std::string& name) const {
    return Environment(*this, SymbolToCode(name));
  }

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  void MDefine(const std::string& name) { set_live(SymbolToCode(name)); }
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  static int SymbolToCode(const std::string& name) {
    SymbolTable::iterator code = symbol_table_.find(name);

    if (code == symbol_table_.end()) {
      int new_code = symbol_table_.size();
      symbol_table_.insert(std::make_pair(name, new_code));
      return new_code;
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    }
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    return code->second;
  }

  static void ClearSymbolTable() {
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    for (Environment* e : envs_) delete e;
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    envs_.clear();
    symbol_table_.clear();
  }

  void Print() const {
    bool comma = false;
    std::cout << "{";
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    for (auto& e : symbol_table_) {
      if (!is_live(e.second)) continue;
      if (comma) std::cout << ", ";
      std::cout << e.first;
      comma = true;
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    }
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    std::cout << "}" << std::endl;
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  }

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  static Environment* Allocate(const Environment& env) {
    Environment* allocated_env = new Environment(env);
    envs_.push_back(allocated_env);
    return allocated_env;
  }

 private:
  Environment(const Environment& l, int code)
      : live_(l.live_) {
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    set_live(code);
  }

  void set_live(size_t pos) {
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    if (unreachable_) return;
    if (pos >= live_.size()) live_.resize(pos + 1);
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    live_[pos] = true;
  }

  bool is_live(size_t pos) const {
    return unreachable_ || (live_.size() > pos && live_[pos]);
  }

  Environment& operator|=(const Environment& o) {
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    if (o.unreachable_) {
      unreachable_ = true;
      live_.clear();
    } else if (!unreachable_) {
      for (size_t i = 0, e = o.live_.size(); i < e; ++i) {
        if (o.live_[i]) set_live(i);
      }
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    }
    return *this;
  }

  Environment& operator&=(const Environment& o) {
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    if (o.unreachable_) return *this;
    if (unreachable_) return *this = o;

    // Carry over false bits from the tail of o.live_, and reset all bits that
    // are not set in o.live_.
    size_t size = std::max(live_.size(), o.live_.size());
    if (size > live_.size()) live_.resize(size);
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    for (size_t i = 0; i < size; ++i) {
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      if (live_[i] && (i >= o.live_.size() || !o.live_[i])) live_[i] = false;
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    }
    return *this;
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  }

  static SymbolTable symbol_table_;
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  static std::vector<Environment*> envs_;
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  std::vector<bool> live_;
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  // unreachable_ == true implies live_.empty(), but still is_live(i) returns
  // true for all i.
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  bool unreachable_ = false;
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  friend class ExprEffect;
  friend class CallProps;
};


class CallProps {
 public:
  CallProps() : env_(NULL) { }

  void SetEffect(int arg, ExprEffect in) {
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    if (in.hasGC()) {
      gc_.set(arg);
    }
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    if (in.hasRawDef()) raw_def_.set(arg);
    if (in.hasRawUse()) raw_use_.set(arg);
    if (in.env() != NULL) {
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      if (env_ == NULL) {
        env_ = in.env();
      } else {
        *env_ |= *in.env();
      }
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    }
  }

  ExprEffect ComputeCumulativeEffect(bool result_is_raw) {
    ExprEffect out = ExprEffect::NoneWithEnv(env_);
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    if (gc_.any()) {
      out.setGC();
    }
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    if (raw_use_.any()) out.setRawUse();
    if (result_is_raw) out.setRawDef();
    return out;
  }

  bool IsSafe() {
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    if (!gc_.any()) {
      return true;
    }
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    std::bitset<kMaxNumberOfArguments> raw = (raw_def_ | raw_use_);
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    if (!raw.any()) {
      return true;
    }
    bool result = gc_.count() == 1 && !((raw ^ gc_).any());
    return result;
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  }

 private:
  static const int kMaxNumberOfArguments = 64;
  std::bitset<kMaxNumberOfArguments> raw_def_;
  std::bitset<kMaxNumberOfArguments> raw_use_;
  std::bitset<kMaxNumberOfArguments> gc_;
  Environment* env_;
};


Environment::SymbolTable Environment::symbol_table_;
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std::vector<Environment*> Environment::envs_;
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ExprEffect ExprEffect::Merge(ExprEffect a, ExprEffect b) {
  Environment* a_env = a.env();
  Environment* b_env = b.env();
  Environment* out = NULL;
  if (a_env != NULL && b_env != NULL) {
    out = Environment::Allocate(*a_env);
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    *out &= *b_env;
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  }
  return ExprEffect(a.effect_ | b.effect_, out);
}


ExprEffect ExprEffect::MergeSeq(ExprEffect a, ExprEffect b) {
  Environment* a_env = b.hasGC() ? NULL : a.env();
  Environment* b_env = b.env();
  Environment* out = (b_env == NULL) ? a_env : b_env;
  if (a_env != NULL && b_env != NULL) {
    out = Environment::Allocate(*b_env);
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    *out |= *a_env;
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  }
  return ExprEffect(a.effect_ | b.effect_, out);
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}


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ExprEffect ExprEffect::Define(const std::string& name) {
  Environment* e = env();
  if (e == NULL) {
    e = Environment::Allocate(Environment());
  }
  e->MDefine(name);
  return ExprEffect(effect_, e);
}


static std::string THIS ("this");


class FunctionAnalyzer {
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 public:
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  FunctionAnalyzer(clang::MangleContext* ctx, clang::CXXRecordDecl* object_decl,
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                   clang::CXXRecordDecl* maybe_object_decl,
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                   clang::CXXRecordDecl* smi_decl,
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                   clang::CXXRecordDecl* no_gc_mole_decl,
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                   clang::DiagnosticsEngine& d, clang::SourceManager& sm)
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      : ctx_(ctx),
        object_decl_(object_decl),
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        maybe_object_decl_(maybe_object_decl),
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        smi_decl_(smi_decl),
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        no_gc_mole_decl_(no_gc_mole_decl),
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        d_(d),
        sm_(sm),
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        block_(NULL) {}
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  // --------------------------------------------------------------------------
  // Expressions
  // --------------------------------------------------------------------------

  ExprEffect VisitExpr(clang::Expr* expr, const Environment& env) {
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#define VISIT(type)                                                         \
  do {                                                                      \
    clang::type* concrete_expr = llvm::dyn_cast_or_null<clang::type>(expr); \
    if (concrete_expr != NULL) {                                            \
      return Visit##type(concrete_expr, env);                               \
    }                                                                       \
  } while (0);
712 713 714 715 716 717 718 719 720 721 722

    VISIT(AbstractConditionalOperator);
    VISIT(AddrLabelExpr);
    VISIT(ArraySubscriptExpr);
    VISIT(BinaryOperator);
    VISIT(BlockExpr);
    VISIT(CallExpr);
    VISIT(CastExpr);
    VISIT(CharacterLiteral);
    VISIT(ChooseExpr);
    VISIT(CompoundLiteralExpr);
723
    VISIT(ConstantExpr);
724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747
    VISIT(CXXBindTemporaryExpr);
    VISIT(CXXBoolLiteralExpr);
    VISIT(CXXConstructExpr);
    VISIT(CXXDefaultArgExpr);
    VISIT(CXXDeleteExpr);
    VISIT(CXXDependentScopeMemberExpr);
    VISIT(CXXNewExpr);
    VISIT(CXXNoexceptExpr);
    VISIT(CXXNullPtrLiteralExpr);
    VISIT(CXXPseudoDestructorExpr);
    VISIT(CXXScalarValueInitExpr);
    VISIT(CXXThisExpr);
    VISIT(CXXThrowExpr);
    VISIT(CXXTypeidExpr);
    VISIT(CXXUnresolvedConstructExpr);
    VISIT(CXXUuidofExpr);
    VISIT(DeclRefExpr);
    VISIT(DependentScopeDeclRefExpr);
    VISIT(DesignatedInitExpr);
    VISIT(ExprWithCleanups);
    VISIT(ExtVectorElementExpr);
    VISIT(FloatingLiteral);
    VISIT(GNUNullExpr);
    VISIT(ImaginaryLiteral);
748
    VISIT(ImplicitCastExpr);
749 750 751
    VISIT(ImplicitValueInitExpr);
    VISIT(InitListExpr);
    VISIT(IntegerLiteral);
752
    VISIT(MaterializeTemporaryExpr);
753 754 755 756 757 758 759 760 761 762 763 764 765
    VISIT(MemberExpr);
    VISIT(OffsetOfExpr);
    VISIT(OpaqueValueExpr);
    VISIT(OverloadExpr);
    VISIT(PackExpansionExpr);
    VISIT(ParenExpr);
    VISIT(ParenListExpr);
    VISIT(PredefinedExpr);
    VISIT(ShuffleVectorExpr);
    VISIT(SizeOfPackExpr);
    VISIT(StmtExpr);
    VISIT(StringLiteral);
    VISIT(SubstNonTypeTemplateParmPackExpr);
766
    VISIT(TypeTraitExpr);
767
    VISIT(UnaryOperator);
768
    VISIT(UnaryExprOrTypeTraitExpr);
769 770 771 772
    VISIT(VAArgExpr);
#undef VISIT

    return ExprEffect::None();
773 774
  }

775 776
#define DECL_VISIT_EXPR(type)                                           \
  ExprEffect Visit##type (clang::type* expr, const Environment& env)
777

778 779 780 781
#define IGNORE_EXPR(type)                                               \
  ExprEffect Visit##type (clang::type* expr, const Environment& env) {  \
    return ExprEffect::None();                                          \
  }
782

783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811
  IGNORE_EXPR(AddrLabelExpr);
  IGNORE_EXPR(BlockExpr);
  IGNORE_EXPR(CharacterLiteral);
  IGNORE_EXPR(ChooseExpr);
  IGNORE_EXPR(CompoundLiteralExpr);
  IGNORE_EXPR(CXXBoolLiteralExpr);
  IGNORE_EXPR(CXXDependentScopeMemberExpr);
  IGNORE_EXPR(CXXNullPtrLiteralExpr);
  IGNORE_EXPR(CXXPseudoDestructorExpr);
  IGNORE_EXPR(CXXScalarValueInitExpr);
  IGNORE_EXPR(CXXNoexceptExpr);
  IGNORE_EXPR(CXXTypeidExpr);
  IGNORE_EXPR(CXXUnresolvedConstructExpr);
  IGNORE_EXPR(CXXUuidofExpr);
  IGNORE_EXPR(DependentScopeDeclRefExpr);
  IGNORE_EXPR(DesignatedInitExpr);
  IGNORE_EXPR(ExtVectorElementExpr);
  IGNORE_EXPR(FloatingLiteral);
  IGNORE_EXPR(ImaginaryLiteral);
  IGNORE_EXPR(IntegerLiteral);
  IGNORE_EXPR(OffsetOfExpr);
  IGNORE_EXPR(ImplicitValueInitExpr);
  IGNORE_EXPR(PackExpansionExpr);
  IGNORE_EXPR(PredefinedExpr);
  IGNORE_EXPR(ShuffleVectorExpr);
  IGNORE_EXPR(SizeOfPackExpr);
  IGNORE_EXPR(StmtExpr);
  IGNORE_EXPR(StringLiteral);
  IGNORE_EXPR(SubstNonTypeTemplateParmPackExpr);
812
  IGNORE_EXPR(TypeTraitExpr);
813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828
  IGNORE_EXPR(VAArgExpr);
  IGNORE_EXPR(GNUNullExpr);
  IGNORE_EXPR(OverloadExpr);

  DECL_VISIT_EXPR(CXXThisExpr) {
    return Use(expr, expr->getType(), THIS, env);
  }

  DECL_VISIT_EXPR(AbstractConditionalOperator) {
    Environment after_cond = env.ApplyEffect(VisitExpr(expr->getCond(), env));
    return ExprEffect::Merge(VisitExpr(expr->getTrueExpr(), after_cond),
                             VisitExpr(expr->getFalseExpr(), after_cond));
  }

  DECL_VISIT_EXPR(ArraySubscriptExpr) {
    clang::Expr* exprs[2] = {expr->getBase(), expr->getIdx()};
829
    return Parallel(expr, 2, exprs, env);
830 831 832
  }

  bool IsRawPointerVar(clang::Expr* expr, std::string* var_name) {
833 834 835
    if (llvm::isa<clang::DeclRefExpr>(expr)) {
      *var_name =
          llvm::cast<clang::DeclRefExpr>(expr)->getDecl()->getNameAsString();
836
      return true;
837
    }
838

839 840 841
    return false;
  }

842 843 844 845 846 847 848
  DECL_VISIT_EXPR(BinaryOperator) {
    clang::Expr* lhs = expr->getLHS();
    clang::Expr* rhs = expr->getRHS();
    clang::Expr* exprs[2] = {lhs, rhs};

    switch (expr->getOpcode()) {
      case clang::BO_Comma:
849
        return Sequential(expr, 2, exprs, env);
850 851 852 853 854 855

      case clang::BO_LAnd:
      case clang::BO_LOr:
        return ExprEffect::Merge(VisitExpr(lhs, env), VisitExpr(rhs, env));

      default:
856
        return Parallel(expr, 2, exprs, env);
857
    }
858 859
  }

860 861
  DECL_VISIT_EXPR(CXXBindTemporaryExpr) {
    return VisitExpr(expr->getSubExpr(), env);
862 863
  }

864 865 866 867
  DECL_VISIT_EXPR(MaterializeTemporaryExpr) {
    return VisitExpr(expr->GetTemporaryExpr(), env);
  }

868 869 870 871 872 873 874 875 876 877 878 879
  DECL_VISIT_EXPR(CXXConstructExpr) {
    return VisitArguments<>(expr, env);
  }

  DECL_VISIT_EXPR(CXXDefaultArgExpr) {
    return VisitExpr(expr->getExpr(), env);
  }

  DECL_VISIT_EXPR(CXXDeleteExpr) {
    return VisitExpr(expr->getArgument(), env);
  }

880
  DECL_VISIT_EXPR(CXXNewExpr) { return VisitExpr(expr->getInitializer(), env); }
881 882 883 884 885 886 887 888 889

  DECL_VISIT_EXPR(ExprWithCleanups) {
    return VisitExpr(expr->getSubExpr(), env);
  }

  DECL_VISIT_EXPR(CXXThrowExpr) {
    return VisitExpr(expr->getSubExpr(), env);
  }

890 891 892 893 894 895
  DECL_VISIT_EXPR(ImplicitCastExpr) {
    return VisitExpr(expr->getSubExpr(), env);
  }

  DECL_VISIT_EXPR(ConstantExpr) { return VisitExpr(expr->getSubExpr(), env); }

896
  DECL_VISIT_EXPR(InitListExpr) {
897
    return Sequential(expr, expr->getNumInits(), expr->getInits(), env);
898 899 900 901 902 903 904 905 906 907 908 909 910 911 912
  }

  DECL_VISIT_EXPR(MemberExpr) {
    return VisitExpr(expr->getBase(), env);
  }

  DECL_VISIT_EXPR(OpaqueValueExpr) {
    return VisitExpr(expr->getSourceExpr(), env);
  }

  DECL_VISIT_EXPR(ParenExpr) {
    return VisitExpr(expr->getSubExpr(), env);
  }

  DECL_VISIT_EXPR(ParenListExpr) {
913
    return Parallel(expr, expr->getNumExprs(), expr->getExprs(), env);
914 915 916
  }

  DECL_VISIT_EXPR(UnaryOperator) {
917
    // TODO(gcmole): We are treating all expressions that look like
918 919
    // {&raw_pointer_var} as definitions of {raw_pointer_var}. This should be
    // changed to recognize less generic pattern:
920
    //
921
    //   if (maybe_object->ToObject(&obj)) return maybe_object;
922 923 924 925 926 927 928 929 930 931
    //
    if (expr->getOpcode() == clang::UO_AddrOf) {
      std::string var_name;
      if (IsRawPointerVar(expr->getSubExpr(), &var_name)) {
        return ExprEffect::None().Define(var_name);
      }
    }
    return VisitExpr(expr->getSubExpr(), env);
  }

932 933 934 935 936 937 938 939
  DECL_VISIT_EXPR(UnaryExprOrTypeTraitExpr) {
    if (expr->isArgumentType()) {
      return ExprEffect::None();
    }

    return VisitExpr(expr->getArgumentExpr(), env);
  }

940 941 942 943 944 945 946 947
  DECL_VISIT_EXPR(CastExpr) {
    return VisitExpr(expr->getSubExpr(), env);
  }

  DECL_VISIT_EXPR(DeclRefExpr) {
    return Use(expr, expr->getDecl(), env);
  }

948 949 950 951
  // Represents a node in the AST {parent} whose children {exprs} have
  // undefined order of evaluation, e.g. array subscript or a binary operator.
  ExprEffect Parallel(clang::Expr* parent, int n, clang::Expr** exprs,
                      const Environment& env) {
952 953 954 955 956 957 958 959
    CallProps props;

    for (int i = 0; i < n; ++i) {
      props.SetEffect(i, VisitExpr(exprs[i], env));
    }

    if (!props.IsSafe()) ReportUnsafe(parent, BAD_EXPR_MSG);

960 961
    return props.ComputeCumulativeEffect(
        RepresentsRawPointerType(parent->getType()));
962 963
  }

964 965 966 967
  // Represents a node in the AST {parent} whose children {exprs} are
  // executed in sequence, e.g. a switch statement or an initializer list.
  ExprEffect Sequential(clang::Stmt* parent, int n, clang::Expr** exprs,
                        const Environment& env) {
968 969 970 971 972 973 974 975 976
    ExprEffect out = ExprEffect::None();
    Environment out_env = env;
    for (int i = 0; i < n; ++i) {
      out = ExprEffect::MergeSeq(out, VisitExpr(exprs[i], out_env));
      out_env = out_env.ApplyEffect(out);
    }
    return out;
  }

977 978 979 980 981 982
  // Represents a node in the AST {parent} which uses the variable {var_name},
  // e.g. this expression or operator&.
  // Here we observe the type in {var_type} of a previously declared variable
  // and if it's a raw heap object type, we do the following:
  // 1. If it got stale due to GC since its declaration, we report it as such.
  // 2. Mark its raw usage in the ExprEffect returned by this function.
983 984 985 986
  ExprEffect Use(const clang::Expr* parent,
                 const clang::QualType& var_type,
                 const std::string& var_name,
                 const Environment& env) {
987 988 989 990 991 992 993
    if (RepresentsRawPointerType(var_type)) {
      // We currently care only about our internal pointer types and not about
      // raw C++ pointers, because normally special care is taken when storing
      // raw pointers to the managed heap. Furthermore, checking for raw
      // pointers produces too many false positives in the dead variable
      // analysis.
      if (IsInternalPointerType(var_type) && !env.IsAlive(var_name) &&
994
          !HasActiveGuard() && g_dead_vars_analysis) {
995
        ReportUnsafe(parent, DEAD_VAR_MSG);
996
      }
997
      return ExprEffect::RawUse();
998
    }
999 1000 1001 1002 1003 1004
    return ExprEffect::None();
  }

  ExprEffect Use(const clang::Expr* parent,
                 const clang::ValueDecl* var,
                 const Environment& env) {
1005 1006 1007
    if (IsExternalVMState(var)) {
      return ExprEffect::GC();
    }
1008 1009 1010
    return Use(parent, var->getType(), var->getNameAsString(), env);
  }

1011

1012 1013 1014 1015 1016
  template<typename ExprType>
  ExprEffect VisitArguments(ExprType* call, const Environment& env) {
    CallProps props;
    VisitArguments<>(call, &props, env);
    if (!props.IsSafe()) ReportUnsafe(call, BAD_EXPR_MSG);
1017 1018
    return props.ComputeCumulativeEffect(
        RepresentsRawPointerType(call->getType()));
1019 1020 1021 1022 1023 1024
  }

  template<typename ExprType>
  void VisitArguments(ExprType* call,
                      CallProps* props,
                      const Environment& env) {
1025
    for (unsigned arg = 0; arg < call->getNumArgs(); arg++) {
1026
      props->SetEffect(arg + 1, VisitExpr(call->getArg(arg), env));
1027 1028 1029
    }
  }

1030 1031 1032
  // After visiting the receiver and the arguments of the {call} node, this
  // function might report a GC-unsafe usage (due to the undefined evaluation
  // order of the receiver and the rest of the arguments).
1033 1034 1035
  ExprEffect VisitCallExpr(clang::CallExpr* call,
                           const Environment& env) {
    CallProps props;
1036 1037

    clang::CXXMemberCallExpr* memcall =
1038
        llvm::dyn_cast_or_null<clang::CXXMemberCallExpr>(call);
1039 1040 1041
    if (memcall != NULL) {
      clang::Expr* receiver = memcall->getImplicitObjectArgument();
      props.SetEffect(0, VisitExpr(receiver, env));
1042 1043
    }

1044 1045 1046 1047 1048
    std::string var_name;
    clang::CXXOperatorCallExpr* opcall =
        llvm::dyn_cast_or_null<clang::CXXOperatorCallExpr>(call);
    if (opcall != NULL && opcall->isAssignmentOp() &&
        IsRawPointerVar(opcall->getArg(0), &var_name)) {
1049
      // TODO(gcmole): We are treating all assignment operator calls with
1050 1051 1052 1053 1054 1055 1056 1057
      // the left hand side looking like {raw_pointer_var} as safe independent
      // of the concrete assignment operator implementation. This should be
      // changed to be more narrow only if the assignment operator of the base
      // {Object} or {HeapObject} class was used, which we know to be safe.
      props.SetEffect(1, VisitExpr(call->getArg(1), env).Define(var_name));
    } else {
      VisitArguments<>(call, &props, env);
    }
1058 1059 1060

    if (!props.IsSafe()) ReportUnsafe(call, BAD_EXPR_MSG);

1061 1062
    ExprEffect out = props.ComputeCumulativeEffect(
        RepresentsRawPointerType(call->getType()));
1063 1064

    clang::FunctionDecl* callee = call->getDirectCallee();
1065 1066 1067
    if (callee != NULL) {
      if (KnownToCauseGC(ctx_, callee)) {
        out.setGC();
1068 1069
        scopes_.back().SetGCCauseLocation(
            clang::FullSourceLoc(call->getExprLoc(), sm_));
1070 1071
      }

1072
      // Support for virtual methods that might be GC suspects.
1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083
      clang::CXXMethodDecl* method =
          llvm::dyn_cast_or_null<clang::CXXMethodDecl>(callee);
      if (method != NULL && method->isVirtual()) {
        clang::CXXMemberCallExpr* memcall =
            llvm::dyn_cast_or_null<clang::CXXMemberCallExpr>(call);
        if (memcall != NULL) {
          clang::CXXMethodDecl* target = method->getDevirtualizedMethod(
              memcall->getImplicitObjectArgument(), false);
          if (target != NULL) {
            if (KnownToCauseGC(ctx_, target)) {
              out.setGC();
1084 1085
              scopes_.back().SetGCCauseLocation(
                  clang::FullSourceLoc(call->getExprLoc(), sm_));
1086 1087
            }
          } else {
1088 1089 1090 1091
            // According to the documentation, {getDevirtualizedMethod} might
            // return NULL, in which case we still want to use the partial
            // match of the {method}'s name against the GC suspects in order
            // to increase coverage.
1092 1093
            if (SuspectedToCauseGC(ctx_, method)) {
              out.setGC();
1094 1095
              scopes_.back().SetGCCauseLocation(
                  clang::FullSourceLoc(call->getExprLoc(), sm_));
1096 1097 1098 1099
            }
          }
        }
      }
1100 1101 1102 1103 1104 1105 1106 1107 1108 1109
    }

    return out;
  }

  // --------------------------------------------------------------------------
  // Statements
  // --------------------------------------------------------------------------

  Environment VisitStmt(clang::Stmt* stmt, const Environment& env) {
1110 1111 1112 1113 1114 1115 1116 1117 1118
#define VISIT(type)                                                         \
  do {                                                                      \
    clang::type* concrete_stmt = llvm::dyn_cast_or_null<clang::type>(stmt); \
    if (concrete_stmt != NULL) {                                            \
      return Visit##type(concrete_stmt, env);                               \
    }                                                                       \
  } while (0);

    if (clang::Expr* expr = llvm::dyn_cast_or_null<clang::Expr>(stmt)) {
1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206
      return env.ApplyEffect(VisitExpr(expr, env));
    }

    VISIT(AsmStmt);
    VISIT(BreakStmt);
    VISIT(CompoundStmt);
    VISIT(ContinueStmt);
    VISIT(CXXCatchStmt);
    VISIT(CXXTryStmt);
    VISIT(DeclStmt);
    VISIT(DoStmt);
    VISIT(ForStmt);
    VISIT(GotoStmt);
    VISIT(IfStmt);
    VISIT(IndirectGotoStmt);
    VISIT(LabelStmt);
    VISIT(NullStmt);
    VISIT(ReturnStmt);
    VISIT(CaseStmt);
    VISIT(DefaultStmt);
    VISIT(SwitchStmt);
    VISIT(WhileStmt);
#undef VISIT

    return env;
  }

#define DECL_VISIT_STMT(type)                                           \
  Environment Visit##type (clang::type* stmt, const Environment& env)

#define IGNORE_STMT(type)                                               \
  Environment Visit##type (clang::type* stmt, const Environment& env) { \
    return env;                                                         \
  }

  IGNORE_STMT(IndirectGotoStmt);
  IGNORE_STMT(NullStmt);
  IGNORE_STMT(AsmStmt);

  // We are ignoring control flow for simplicity.
  IGNORE_STMT(GotoStmt);
  IGNORE_STMT(LabelStmt);

  // We are ignoring try/catch because V8 does not use them.
  IGNORE_STMT(CXXCatchStmt);
  IGNORE_STMT(CXXTryStmt);

  class Block {
   public:
    Block(const Environment& in,
          FunctionAnalyzer* owner)
        : in_(in),
          out_(Environment::Unreachable()),
          changed_(false),
          owner_(owner) {
      parent_ = owner_->EnterBlock(this);
    }

    ~Block() {
      owner_->LeaveBlock(parent_);
    }

    void MergeIn(const Environment& env) {
      Environment old_in = in_;
      in_ = Environment::Merge(in_, env);
      changed_ = !old_in.Equal(in_);
    }

    bool changed() {
      if (changed_) {
        changed_ = false;
        return true;
      }
      return false;
    }

    const Environment& in() {
      return in_;
    }

    const Environment& out() {
      return out_;
    }

    void MergeOut(const Environment& env) {
      out_ = Environment::Merge(out_, env);
    }

1207
    void Sequential(clang::Stmt* a, clang::Stmt* b, clang::Stmt* c) {
1208 1209 1210 1211 1212 1213
      Environment a_out = owner_->VisitStmt(a, in());
      Environment b_out = owner_->VisitStmt(b, a_out);
      Environment c_out = owner_->VisitStmt(c, b_out);
      MergeOut(c_out);
    }

1214
    void Sequential(clang::Stmt* a, clang::Stmt* b) {
1215 1216 1217 1218 1219 1220
      Environment a_out = owner_->VisitStmt(a, in());
      Environment b_out = owner_->VisitStmt(b, a_out);
      MergeOut(b_out);
    }

    void Loop(clang::Stmt* a, clang::Stmt* b, clang::Stmt* c) {
1221
      Sequential(a, b, c);
1222 1223 1224 1225
      MergeIn(out());
    }

    void Loop(clang::Stmt* a, clang::Stmt* b) {
1226
      Sequential(a, b);
1227
      MergeIn(out());
1228
    }
1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250


   private:
    Environment in_;
    Environment out_;
    bool changed_;
    FunctionAnalyzer* owner_;
    Block* parent_;
  };


  DECL_VISIT_STMT(BreakStmt) {
    block_->MergeOut(env);
    return Environment::Unreachable();
  }

  DECL_VISIT_STMT(ContinueStmt) {
    block_->MergeIn(env);
    return Environment::Unreachable();
  }

  DECL_VISIT_STMT(CompoundStmt) {
1251
    scopes_.push_back(GCScope());
1252 1253 1254 1255 1256 1257 1258
    Environment out = env;
    clang::CompoundStmt::body_iterator end = stmt->body_end();
    for (clang::CompoundStmt::body_iterator s = stmt->body_begin();
         s != end;
         ++s) {
      out = VisitStmt(*s, out);
    }
1259
    scopes_.pop_back();
1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281
    return out;
  }

  DECL_VISIT_STMT(WhileStmt) {
    Block block (env, this);
    do {
      block.Loop(stmt->getCond(), stmt->getBody());
    } while (block.changed());
    return block.out();
  }

  DECL_VISIT_STMT(DoStmt) {
    Block block (env, this);
    do {
      block.Loop(stmt->getBody(), stmt->getCond());
    } while (block.changed());
    return block.out();
  }

  DECL_VISIT_STMT(ForStmt) {
    Block block (VisitStmt(stmt->getInit(), env), this);
    do {
1282
      block.Loop(stmt->getCond(), stmt->getBody(), stmt->getInc());
1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295
    } while (block.changed());
    return block.out();
  }

  DECL_VISIT_STMT(IfStmt) {
    Environment cond_out = VisitStmt(stmt->getCond(), env);
    Environment then_out = VisitStmt(stmt->getThen(), cond_out);
    Environment else_out = VisitStmt(stmt->getElse(), cond_out);
    return Environment::Merge(then_out, else_out);
  }

  DECL_VISIT_STMT(SwitchStmt) {
    Block block (env, this);
1296
    block.Sequential(stmt->getCond(), stmt->getBody());
1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313
    return block.out();
  }

  DECL_VISIT_STMT(CaseStmt) {
    Environment in = Environment::Merge(env, block_->in());
    Environment after_lhs = VisitStmt(stmt->getLHS(), in);
    return VisitStmt(stmt->getSubStmt(), after_lhs);
  }

  DECL_VISIT_STMT(DefaultStmt) {
    Environment in = Environment::Merge(env, block_->in());
    return VisitStmt(stmt->getSubStmt(), in);
  }

  DECL_VISIT_STMT(ReturnStmt) {
    VisitExpr(stmt->getRetValue(), env);
    return Environment::Unreachable();
1314 1315 1316 1317 1318
  }

  const clang::TagType* ToTagType(const clang::Type* t) {
    if (t == NULL) {
      return NULL;
1319 1320 1321 1322 1323 1324
    } else if (llvm::isa<clang::TagType>(t)) {
      return llvm::cast<clang::TagType>(t);
    } else if (llvm::isa<clang::SubstTemplateTypeParmType>(t)) {
      return ToTagType(llvm::cast<clang::SubstTemplateTypeParmType>(t)
                           ->getReplacementType()
                           .getTypePtr());
1325 1326 1327 1328 1329
    } else {
      return NULL;
    }
  }

1330 1331
  bool IsDerivedFrom(const clang::CXXRecordDecl* record,
                     const clang::CXXRecordDecl* base) {
1332 1333
    return (record == base) || record->isDerivedFrom(base);
  }
1334

1335 1336
  const clang::CXXRecordDecl* GetDefinitionOrNull(
      const clang::CXXRecordDecl* record) {
1337
    if (record == NULL) return NULL;
1338
    if (!InV8Namespace(record)) return NULL;
1339
    if (!record->hasDefinition()) return NULL;
1340 1341 1342
    return record->getDefinition();
  }

1343
  bool IsDerivedFromInternalPointer(const clang::CXXRecordDecl* record) {
1344
    const clang::CXXRecordDecl* definition = GetDefinitionOrNull(record);
1345
    if (!definition) return false;
1346 1347 1348 1349
    bool result = (IsDerivedFrom(record, object_decl_) &&
                   !IsDerivedFrom(record, smi_decl_)) ||
                  IsDerivedFrom(record, maybe_object_decl_);
    return result;
1350
  }
1351

1352 1353 1354 1355 1356 1357 1358
  bool IsRawPointerType(const clang::PointerType* type) {
    const clang::CXXRecordDecl* record = type->getPointeeCXXRecordDecl();
    bool result = IsDerivedFromInternalPointer(record);
    TRACE("is raw " << result << " " << record->getNameAsString());
    return result;
  }

1359
  bool IsInternalPointerType(clang::QualType qtype) {
1360 1361 1362
    const clang::CXXRecordDecl* record = qtype->getAsCXXRecordDecl();
    bool result = IsDerivedFromInternalPointer(record);
    TRACE_LLVM_TYPE("is internal " << result, qtype);
1363
    return result;
1364 1365 1366 1367 1368
  }

  // Returns weather the given type is a raw pointer or a wrapper around
  // such. For V8 that means Object and MaybeObject instances.
  bool RepresentsRawPointerType(clang::QualType qtype) {
1369
    // Not yet assigned pointers can't get moved by the GC.
1370
    if (qtype.isNull()) return false;
1371
    // nullptr can't get moved by the GC.
1372
    if (qtype->isNullPtrType()) return false;
1373

1374 1375 1376
    const clang::PointerType* pointer_type =
        llvm::dyn_cast_or_null<clang::PointerType>(qtype.getTypePtrOrNull());
    if (pointer_type != NULL) {
1377
      return IsRawPointerType(pointer_type);
1378 1379 1380
    } else {
      return IsInternalPointerType(qtype);
    }
1381 1382
  }

1383
  bool IsGCGuard(clang::QualType qtype) {
1384 1385 1386
    if (!no_gc_mole_decl_) return false;
    if (qtype.isNull()) return false;
    if (qtype->isNullPtrType()) return false;
1387 1388 1389 1390

    const clang::CXXRecordDecl* record = qtype->getAsCXXRecordDecl();
    const clang::CXXRecordDecl* definition = GetDefinitionOrNull(record);

1391 1392
    if (!definition) return false;
    return no_gc_mole_decl_ == definition;
1393 1394 1395
  }

  Environment VisitDecl(clang::Decl* decl, Environment& env) {
1396
    if (clang::VarDecl* var = llvm::dyn_cast<clang::VarDecl>(decl)) {
1397 1398
      Environment out = var->hasInit() ? VisitStmt(var->getInit(), env) : env;

1399
      if (RepresentsRawPointerType(var->getType())) {
1400 1401
        out = out.Define(var->getNameAsString());
      }
1402
      if (IsGCGuard(var->getType())) {
1403 1404
        scopes_.back().guard_location =
            clang::FullSourceLoc(decl->getLocation(), sm_);
1405
      }
1406

1407 1408
      return out;
    }
1409
    // TODO(gcmole): handle other declarations?
1410
    return env;
1411 1412
  }

1413 1414 1415 1416 1417 1418 1419 1420 1421
  DECL_VISIT_STMT(DeclStmt) {
    Environment out = env;
    clang::DeclStmt::decl_iterator end = stmt->decl_end();
    for (clang::DeclStmt::decl_iterator decl = stmt->decl_begin();
         decl != end;
         ++decl) {
      out = VisitDecl(*decl, out);
    }
    return out;
1422 1423 1424
  }


1425 1426 1427 1428 1429 1430 1431 1432 1433 1434
  void DefineParameters(const clang::FunctionDecl* f,
                        Environment* env) {
    env->MDefine(THIS);
    clang::FunctionDecl::param_const_iterator end = f->param_end();
    for (clang::FunctionDecl::param_const_iterator p = f->param_begin();
         p != end;
         ++p) {
      env->MDefine((*p)->getNameAsString());
    }
  }
1435 1436


1437 1438 1439 1440 1441 1442 1443 1444 1445
  void AnalyzeFunction(const clang::FunctionDecl* f) {
    const clang::FunctionDecl* body = NULL;
    if (f->hasBody(body)) {
      Environment env;
      DefineParameters(body, &env);
      VisitStmt(body->getBody(), env);
      Environment::ClearSymbolTable();
    }
  }
1446

1447 1448 1449 1450 1451
  Block* EnterBlock(Block* block) {
    Block* parent = block_;
    block_ = block;
    return parent;
  }
1452

1453 1454 1455
  void LeaveBlock(Block* block) {
    block_ = block;
  }
1456

1457 1458
  bool HasActiveGuard() {
    for (auto s : scopes_) {
1459
      if (s.IsBeforeGCCause()) return true;
1460 1461 1462 1463
    }
    return false;
  }

1464 1465 1466
 private:
  void ReportUnsafe(const clang::Expr* expr, const std::string& msg) {
    d_.Report(clang::FullSourceLoc(expr->getExprLoc(), sm_),
1467 1468
              d_.getCustomDiagID(clang::DiagnosticsEngine::Warning, "%0"))
        << msg;
1469
  }
1470 1471


1472 1473
  clang::MangleContext* ctx_;
  clang::CXXRecordDecl* object_decl_;
1474
  clang::CXXRecordDecl* maybe_object_decl_;
1475
  clang::CXXRecordDecl* smi_decl_;
1476
  clang::CXXRecordDecl* no_gc_mole_decl_;
1477
  clang::CXXRecordDecl* no_heap_access_decl_;
1478

1479
  clang::DiagnosticsEngine& d_;
1480
  clang::SourceManager& sm_;
1481

1482
  Block* block_;
1483

1484 1485 1486
  struct GCScope {
    clang::FullSourceLoc guard_location;
    clang::FullSourceLoc gccause_location;
1487

1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501
    // We're only interested in guards that are declared before any further GC
    // causing calls (see TestGuardedDeadVarAnalysisMidFunction for example).
    bool IsBeforeGCCause() {
      if (!guard_location.isValid()) return false;
      if (!gccause_location.isValid()) return true;
      return guard_location.isBeforeInTranslationUnitThan(gccause_location);
    }

    // After we set the first GC cause in the scope, we don't need the later
    // ones.
    void SetGCCauseLocation(clang::FullSourceLoc gccause_location_) {
      if (gccause_location.isValid()) return;
      gccause_location = gccause_location_;
    }
1502
  };
1503
  std::vector<GCScope> scopes_;
1504
};
1505

1506 1507 1508
class ProblemsFinder : public clang::ASTConsumer,
                       public clang::RecursiveASTVisitor<ProblemsFinder> {
 public:
1509
  ProblemsFinder(clang::DiagnosticsEngine& d, clang::SourceManager& sm,
1510
                 const std::vector<std::string>& args)
1511
      : d_(d), sm_(sm) {
1512 1513
    for (unsigned i = 0; i < args.size(); ++i) {
      if (args[i] == "--dead-vars") {
1514
        g_dead_vars_analysis = true;
1515
      }
1516 1517 1518
      if (args[i] == "--verbose") {
        g_tracing_enabled = true;
      }
1519
    }
1520
  }
1521

1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539
  bool TranslationUnitIgnored() {
    if (!ignored_files_loaded_) {
      std::ifstream fin("tools/gcmole/ignored_files");
      std::string s;
      while (fin >> s) ignored_files_.insert(s);
      ignored_files_loaded_ = true;
    }

    clang::FileID main_file_id = sm_.getMainFileID();
    std::string filename = sm_.getFileEntryForID(main_file_id)->getName().str();

    bool result = ignored_files_.find(filename) != ignored_files_.end();
    if (result) {
      llvm::outs() << "Ignoring file " << filename << "\n";
    }
    return result;
  }

1540
  virtual void HandleTranslationUnit(clang::ASTContext &ctx) {
1541
    if (TranslationUnitIgnored()) return;
1542

1543 1544
    Resolver r(ctx);

1545 1546 1547 1548 1549 1550
    // It is a valid situation that no_gc_mole_decl == NULL when DisableGCMole
    // is not included and can't be resolved. This is gracefully handled in the
    // FunctionAnalyzer later.
    auto v8_internal = r.ResolveNamespace("v8").ResolveNamespace("internal");
    clang::CXXRecordDecl* no_gc_mole_decl =
        v8_internal.ResolveTemplate("DisableGCMole");
1551

1552
    clang::CXXRecordDecl* object_decl =
1553
        v8_internal.Resolve<clang::CXXRecordDecl>("Object");
1554

1555
    clang::CXXRecordDecl* maybe_object_decl =
1556
        v8_internal.Resolve<clang::CXXRecordDecl>("MaybeObject");
1557

1558
    clang::CXXRecordDecl* smi_decl =
1559
        v8_internal.Resolve<clang::CXXRecordDecl>("Smi");
1560 1561 1562

    if (object_decl != NULL) object_decl = object_decl->getDefinition();

1563
    if (maybe_object_decl != NULL) {
1564
      maybe_object_decl = maybe_object_decl->getDefinition();
1565
    }
1566

1567 1568
    if (smi_decl != NULL) smi_decl = smi_decl->getDefinition();

1569
    if (object_decl != NULL && smi_decl != NULL && maybe_object_decl != NULL) {
1570 1571
      function_analyzer_ = new FunctionAnalyzer(
          clang::ItaniumMangleContext::create(ctx, d_), object_decl,
1572
          maybe_object_decl, smi_decl, no_gc_mole_decl, d_, sm_);
1573 1574
      TraverseDecl(ctx.getTranslationUnitDecl());
    } else {
1575 1576 1577
      if (object_decl == NULL) {
        llvm::errs() << "Failed to resolve v8::internal::Object\n";
      }
1578 1579 1580
      if (maybe_object_decl == NULL) {
        llvm::errs() << "Failed to resolve v8::internal::MaybeObject\n";
      }
1581 1582 1583
      if (smi_decl == NULL) {
        llvm::errs() << "Failed to resolve v8::internal::Smi\n";
      }
1584 1585 1586
    }
  }

1587
  virtual bool VisitFunctionDecl(clang::FunctionDecl* decl) {
1588 1589 1590 1591 1592 1593 1594 1595
    // Don't print tracing from includes, otherwise the output is too big.
    bool tracing = g_tracing_enabled;
    const auto& fileID = sm_.getFileID(decl->getLocation());
    if (fileID != sm_.getMainFileID()) {
      g_tracing_enabled = false;
    }

    TRACE("Visiting function " << decl->getNameAsString());
1596
    function_analyzer_->AnalyzeFunction(decl);
1597 1598

    g_tracing_enabled = tracing;
1599 1600 1601 1602
    return true;
  }

 private:
1603
  clang::DiagnosticsEngine& d_;
1604 1605
  clang::SourceManager& sm_;

1606 1607 1608
  bool ignored_files_loaded_ = false;
  std::set<std::string> ignored_files_;

1609
  FunctionAnalyzer* function_analyzer_;
1610 1611 1612 1613 1614 1615
};


template<typename ConsumerType>
class Action : public clang::PluginASTAction {
 protected:
1616 1617 1618 1619
  virtual std::unique_ptr<clang::ASTConsumer> CreateASTConsumer(
      clang::CompilerInstance& CI, llvm::StringRef InFile) {
    return std::unique_ptr<clang::ASTConsumer>(
        new ConsumerType(CI.getDiagnostics(), CI.getSourceManager(), args_));
1620 1621 1622 1623
  }

  bool ParseArgs(const clang::CompilerInstance &CI,
                 const std::vector<std::string>& args) {
1624
    args_ = args;
1625 1626 1627
    return true;
  }

1628 1629 1630 1631
  void PrintHelp(llvm::raw_ostream& ros) {
  }
 private:
  std::vector<std::string> args_;
1632 1633 1634 1635 1636
};


}

1637 1638
static clang::FrontendPluginRegistry::Add<Action<ProblemsFinder> >
FindProblems("find-problems", "Find GC-unsafe places.");
1639

1640 1641
static clang::FrontendPluginRegistry::Add<
  Action<FunctionDeclarationFinder> >
1642
DumpCallees("dump-callees", "Dump callees for each function.");
1643 1644 1645 1646 1647 1648 1649 1650

#undef TRACE
#undef TRACE_LLVM_TYPE
#undef TRACE_LLVM_DECL
#undef DECL_VISIT_EXPR
#undef IGNORE_EXPR
#undef DECL_VISIT_STMT
#undef IGNORE_STMT