llvm-project/lldb/source/Core/Mangled.cpp

//===-- Mangled.cpp ---------------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "lldb/Core/Mangled.h"

#if defined(_WIN32)
#include "lldb/Host/windows/windows.h"

#include <dbghelp.h>
#pragma comment(lib, "dbghelp.lib")
#endif

#ifdef LLDB_USE_BUILTIN_DEMANGLER
// Provide a fast-path demangler implemented in FastDemangle.cpp until it can
// replace the existing C++ demangler with a complete implementation
#include "lldb/Utility/FastDemangle.h"
#include "llvm/Demangle/Demangle.h"
#else
// FreeBSD9-STABLE requires this to know about size_t in cxxabi.
#include <cstddef>
#include <cxxabi.h>
#endif

#include "lldb/Core/Timer.h"
#include "lldb/Utility/ConstString.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/Logging.h"
#include "lldb/Utility/RegularExpression.h"
#include "lldb/Utility/Stream.h"
#include "lldb/lldb-enumerations.h" // for LanguageType

#include "Plugins/Language/CPlusPlus/CPlusPlusLanguage.h"
#include "Plugins/Language/ObjC/ObjCLanguage.h"

#include "llvm/ADT/StringRef.h"    // for StringRef
#include "llvm/Support/Compiler.h" // for LLVM_PRETT...

#include <mutex>   // for mutex, loc...
#include <string>  // for string
#include <utility> // for pair

#include <stdlib.h>
#include <string.h>
using namespace lldb_private;

#if defined(_MSC_VER)
static DWORD safeUndecorateName(const char *Mangled, char *Demangled,
                                DWORD DemangledLength) {
  static std::mutex M;
  std::lock_guard<std::mutex> Lock(M);
  return ::UnDecorateSymbolName(
      Mangled, Demangled, DemangledLength,
      UNDNAME_NO_ACCESS_SPECIFIERS |       // Strip public, private, protected
                                           // keywords
          UNDNAME_NO_ALLOCATION_LANGUAGE | // Strip __thiscall, __stdcall,
                                           // etc keywords
          UNDNAME_NO_THROW_SIGNATURES |    // Strip throw() specifications
          UNDNAME_NO_MEMBER_TYPE |         // Strip virtual, static, etc
                                           // specifiers
          UNDNAME_NO_MS_KEYWORDS           // Strip all MS extension keywords
      );
}
#endif

static inline Mangled::ManglingScheme cstring_mangling_scheme(const char *s) {
  if (s) {
    if (s[0] == '?')
      return Mangled::eManglingSchemeMSVC;
    if (s[0] == '_' && s[1] == 'Z')
      return Mangled::eManglingSchemeItanium;
  }
  return Mangled::eManglingSchemeNone;
}

static inline bool cstring_is_mangled(const char *s) {
  return cstring_mangling_scheme(s) != Mangled::eManglingSchemeNone;
}

static const ConstString &
get_demangled_name_without_arguments(ConstString mangled,
                                     ConstString demangled) {
  // This pair is <mangled name, demangled name without function arguments>
  static std::pair<ConstString, ConstString>
      g_most_recent_mangled_to_name_sans_args;

  // Need to have the mangled & demangled names we're currently examining as
  // statics
  // so we can return a const ref to them at the end of the func if we don't
  // have
  // anything better.
  static ConstString g_last_mangled;
  static ConstString g_last_demangled;

  if (mangled && g_most_recent_mangled_to_name_sans_args.first == mangled) {
    return g_most_recent_mangled_to_name_sans_args.second;
  }

  g_last_demangled = demangled;
  g_last_mangled = mangled;

  const char *mangled_name_cstr = mangled.GetCString();

  if (demangled && mangled_name_cstr && mangled_name_cstr[0]) {
    if (mangled_name_cstr[0] == '_' && mangled_name_cstr[1] == 'Z' &&
        (mangled_name_cstr[2] != 'T' && // avoid virtual table, VTT structure,
                                        // typeinfo structure, and typeinfo
                                        // mangled_name
         mangled_name_cstr[2] != 'G' && // avoid guard variables
         mangled_name_cstr[2] != 'Z')) // named local entities (if we eventually
                                       // handle eSymbolTypeData, we will want
                                       // this back)
    {
      CPlusPlusLanguage::MethodName cxx_method(demangled);
      if (!cxx_method.GetBasename().empty()) {
        std::string shortname;
        if (!cxx_method.GetContext().empty())
          shortname = cxx_method.GetContext().str() + "::";
        shortname += cxx_method.GetBasename().str();
        ConstString result(shortname.c_str());
        g_most_recent_mangled_to_name_sans_args.first = mangled;
        g_most_recent_mangled_to_name_sans_args.second = result;
        return g_most_recent_mangled_to_name_sans_args.second;
      }
    }
  }

  if (demangled)
    return g_last_demangled;
  return g_last_mangled;
}

#pragma mark Mangled
//----------------------------------------------------------------------
// Default constructor
//----------------------------------------------------------------------
Mangled::Mangled() : m_mangled(), m_demangled() {}

//----------------------------------------------------------------------
// Constructor with an optional string and a boolean indicating if it is
// the mangled version.
//----------------------------------------------------------------------
Mangled::Mangled(const ConstString &s, bool mangled)
    : m_mangled(), m_demangled() {
  if (s)
    SetValue(s, mangled);
}

Mangled::Mangled(llvm::StringRef name, bool is_mangled) {
  if (!name.empty())
    SetValue(ConstString(name), is_mangled);
}

Mangled::Mangled(const ConstString &s) : m_mangled(), m_demangled() {
  if (s)
    SetValue(s);
}

Mangled::Mangled(llvm::StringRef name) {
  if (!name.empty())
    SetValue(ConstString(name));
}

//----------------------------------------------------------------------
// Destructor
//----------------------------------------------------------------------
Mangled::~Mangled() {}

//----------------------------------------------------------------------
// Convert to pointer operator. This allows code to check any Mangled
// objects to see if they contain anything valid using code such as:
//
//  Mangled mangled(...);
//  if (mangled)
//  { ...
//----------------------------------------------------------------------
Mangled::operator void *() const {
  return (m_mangled) ? const_cast<Mangled *>(this) : NULL;
}

//----------------------------------------------------------------------
// Logical NOT operator. This allows code to check any Mangled
// objects to see if they are invalid using code such as:
//
//  Mangled mangled(...);
//  if (!file_spec)
//  { ...
//----------------------------------------------------------------------
bool Mangled::operator!() const { return !m_mangled; }

//----------------------------------------------------------------------
// Clear the mangled and demangled values.
//----------------------------------------------------------------------
void Mangled::Clear() {
  m_mangled.Clear();
  m_demangled.Clear();
}

//----------------------------------------------------------------------
// Compare the string values.
//----------------------------------------------------------------------
int Mangled::Compare(const Mangled &a, const Mangled &b) {
  return ConstString::Compare(
      a.GetName(lldb::eLanguageTypeUnknown, ePreferMangled),
      a.GetName(lldb::eLanguageTypeUnknown, ePreferMangled));
}

//----------------------------------------------------------------------
// Set the string value in this objects. If "mangled" is true, then
// the mangled named is set with the new value in "s", else the
// demangled name is set.
//----------------------------------------------------------------------
void Mangled::SetValue(const ConstString &s, bool mangled) {
  if (s) {
    if (mangled) {
      m_demangled.Clear();
      m_mangled = s;
    } else {
      m_demangled = s;
      m_mangled.Clear();
    }
  } else {
    m_demangled.Clear();
    m_mangled.Clear();
  }
}

void Mangled::SetValue(const ConstString &name) {
  if (name) {
    if (cstring_is_mangled(name.GetCString())) {
      m_demangled.Clear();
      m_mangled = name;
    } else {
      m_demangled = name;
      m_mangled.Clear();
    }
  } else {
    m_demangled.Clear();
    m_mangled.Clear();
  }
}

//----------------------------------------------------------------------
// Generate the demangled name on demand using this accessor. Code in
// this class will need to use this accessor if it wishes to decode
// the demangled name. The result is cached and will be kept until a
// new string value is supplied to this object, or until the end of the
// object's lifetime.
//----------------------------------------------------------------------
const ConstString &
Mangled::GetDemangledName(lldb::LanguageType language) const {
  // Check to make sure we have a valid mangled name and that we
  // haven't already decoded our mangled name.
  if (m_mangled && !m_demangled) {
    // We need to generate and cache the demangled name.
    static Timer::Category func_cat(LLVM_PRETTY_FUNCTION);
    Timer scoped_timer(func_cat, "Mangled::GetDemangledName (m_mangled = %s)",
                       m_mangled.GetCString());

    Log *log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_DEMANGLE);

    // Don't bother running anything that isn't mangled
    const char *mangled_name = m_mangled.GetCString();
    ManglingScheme mangling_scheme{cstring_mangling_scheme(mangled_name)};
    if (mangling_scheme != eManglingSchemeNone &&
        !m_mangled.GetMangledCounterpart(m_demangled)) {
      // We didn't already mangle this name, demangle it and if all goes well
      // add it to our map.
      char *demangled_name = nullptr;
      switch (mangling_scheme) {
      case eManglingSchemeMSVC: {
#if defined(_MSC_VER)
        if (log)
          log->Printf("demangle msvc: %s", mangled_name);
        const size_t demangled_length = 2048;
        demangled_name = static_cast<char *>(::malloc(demangled_length));
        ::ZeroMemory(demangled_name, demangled_length);
        DWORD result =
            safeUndecorateName(mangled_name, demangled_name, demangled_length);
        if (log) {
          if (demangled_name && demangled_name[0])
            log->Printf("demangled msvc: %s -> \"%s\"", mangled_name,
                        demangled_name);
          else
            log->Printf("demangled msvc: %s -> error: 0x%lu", mangled_name,
                        result);
        }

        if (result == 0) {
          free(demangled_name);
          demangled_name = nullptr;
        }
#endif
        break;
      }
      case eManglingSchemeItanium: {
#ifdef LLDB_USE_BUILTIN_DEMANGLER
        if (log)
          log->Printf("demangle itanium: %s", mangled_name);
        // Try to use the fast-path demangler first for the
        // performance win, falling back to the full demangler only
        // when necessary
        demangled_name = FastDemangle(mangled_name, m_mangled.GetLength());
        if (!demangled_name)
          demangled_name =
              llvm::itaniumDemangle(mangled_name, NULL, NULL, NULL);
#else
        demangled_name = abi::__cxa_demangle(mangled_name, NULL, NULL, NULL);
#endif
        if (log) {
          if (demangled_name)
            log->Printf("demangled itanium: %s -> \"%s\"", mangled_name,
                        demangled_name);
          else
            log->Printf("demangled itanium: %s -> error: failed to demangle",
                        mangled_name);
        }
        break;
      }
      case eManglingSchemeNone:
        break;
      }
      if (demangled_name) {
        m_demangled.SetCStringWithMangledCounterpart(demangled_name, m_mangled);
        free(demangled_name);
      }
    }
    if (!m_demangled) {
      // Set the demangled string to the empty string to indicate we
      // tried to parse it once and failed.
      m_demangled.SetCString("");
    }
  }

  return m_demangled;
}

ConstString
Mangled::GetDisplayDemangledName(lldb::LanguageType language) const {
  return GetDemangledName(language);
}

bool Mangled::NameMatches(const RegularExpression &regex,
                          lldb::LanguageType language) const {
  if (m_mangled && regex.Execute(m_mangled.AsCString()))
    return true;

  ConstString demangled = GetDemangledName(language);
  if (demangled && regex.Execute(demangled.AsCString()))
    return true;
  return false;
}

//----------------------------------------------------------------------
// Get the demangled name if there is one, else return the mangled name.
//----------------------------------------------------------------------
ConstString Mangled::GetName(lldb::LanguageType language,
                             Mangled::NamePreference preference) const {
  if (preference == ePreferMangled && m_mangled)
    return m_mangled;

  ConstString demangled = GetDemangledName(language);

  if (preference == ePreferDemangledWithoutArguments) {
    return get_demangled_name_without_arguments(m_mangled, demangled);
  }
  if (preference == ePreferDemangled) {
    // Call the accessor to make sure we get a demangled name in case
    // it hasn't been demangled yet...
    if (demangled)
      return demangled;
    return m_mangled;
  }
  return demangled;
}

//----------------------------------------------------------------------
// Dump a Mangled object to stream "s". We don't force our
// demangled name to be computed currently (we don't use the accessor).
//----------------------------------------------------------------------
void Mangled::Dump(Stream *s) const {
  if (m_mangled) {
    *s << ", mangled = " << m_mangled;
  }
  if (m_demangled) {
    const char *demangled = m_demangled.AsCString();
    s->Printf(", demangled = %s", demangled[0] ? demangled : "<error>");
  }
}

//----------------------------------------------------------------------
// Dumps a debug version of this string with extra object and state
// information to stream "s".
//----------------------------------------------------------------------
void Mangled::DumpDebug(Stream *s) const {
  s->Printf("%*p: Mangled mangled = ", static_cast<int>(sizeof(void *) * 2),
            static_cast<const void *>(this));
  m_mangled.DumpDebug(s);
  s->Printf(", demangled = ");
  m_demangled.DumpDebug(s);
}

//----------------------------------------------------------------------
// Return the size in byte that this object takes in memory. The size
// includes the size of the objects it owns, and not the strings that
// it references because they are shared strings.
//----------------------------------------------------------------------
size_t Mangled::MemorySize() const {
  return m_mangled.MemorySize() + m_demangled.MemorySize();
}

//----------------------------------------------------------------------
// We "guess" the language because we can't determine a symbol's language
// from it's name.  For example, a Pascal symbol can be mangled using the
// C++ Itanium scheme, and defined in a compilation unit within the same
// module as other C++ units.  In addition, different targets could have
// different ways of mangling names from a given language, likewise the
// compilation units within those targets.
//----------------------------------------------------------------------
lldb::LanguageType Mangled::GuessLanguage() const {
  ConstString mangled = GetMangledName();
  if (mangled) {
    if (GetDemangledName(lldb::eLanguageTypeUnknown)) {
      const char *mangled_name = mangled.GetCString();
      if (CPlusPlusLanguage::IsCPPMangledName(mangled_name))
        return lldb::eLanguageTypeC_plus_plus;
      else if (ObjCLanguage::IsPossibleObjCMethodName(mangled_name))
        return lldb::eLanguageTypeObjC;
    }
  } else {
    // ObjC names aren't really mangled, so they won't necessarily be in the 
    // mangled name slot.
    ConstString demangled_name = GetDemangledName(lldb::eLanguageTypeUnknown);
    if (demangled_name 
        && ObjCLanguage::IsPossibleObjCMethodName(demangled_name.GetCString()))
      return lldb::eLanguageTypeObjC;
  
  }
  return lldb::eLanguageTypeUnknown;
}

//----------------------------------------------------------------------
// Dump OBJ to the supplied stream S.
//----------------------------------------------------------------------
Stream &operator<<(Stream &s, const Mangled &obj) {
  if (obj.GetMangledName())
    s << "mangled = '" << obj.GetMangledName() << "'";

  const ConstString &demangled =
      obj.GetDemangledName(lldb::eLanguageTypeUnknown);
  if (demangled)
    s << ", demangled = '" << demangled << '\'';
  else
    s << ", demangled = <error>";
  return s;
}