LLVMSymbolize.cpp

//===-- LLVMSymbolize.cpp -------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Implementation for LLVM symbolization library.
//
//===----------------------------------------------------------------------===//

#include "LLVMSymbolize.h"
#include "llvm/Object/MachO.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Path.h"

#include <sstream>

namespace llvm {
namespace symbolize {

static uint32_t getDILineInfoSpecifierFlags(
    const LLVMSymbolizer::Options &Opts) {
  uint32_t Flags = llvm::DILineInfoSpecifier::FileLineInfo |
                   llvm::DILineInfoSpecifier::AbsoluteFilePath;
  if (Opts.PrintFunctions)
    Flags |= llvm::DILineInfoSpecifier::FunctionName;
  return Flags;
}

static void patchFunctionNameInDILineInfo(const std::string &NewFunctionName,
                                          DILineInfo &LineInfo) {
  std::string FileName = LineInfo.getFileName();
  LineInfo = DILineInfo(StringRef(FileName), StringRef(NewFunctionName),
                        LineInfo.getLine(), LineInfo.getColumn());
}

DILineInfo ModuleInfo::symbolizeCode(uint64_t ModuleOffset,
    const LLVMSymbolizer::Options& Opts) const {
  DILineInfo LineInfo;
  if (DebugInfoContext) {
    LineInfo = DebugInfoContext->getLineInfoForAddress(
        ModuleOffset, getDILineInfoSpecifierFlags(Opts));
  }
  // Override function name from symbol table if necessary.
  if (Opts.PrintFunctions && Opts.UseSymbolTable) {
    std::string FunctionName;
    uint64_t Start, Size;
    if (getNameFromSymbolTable(SymbolRef::ST_Function,
                               ModuleOffset, FunctionName, Start, Size)) {
      patchFunctionNameInDILineInfo(FunctionName, LineInfo);
    }
  }
  return LineInfo;
}

DIInliningInfo ModuleInfo::symbolizeInlinedCode(uint64_t ModuleOffset,
    const LLVMSymbolizer::Options& Opts) const {
  DIInliningInfo InlinedContext;
  if (DebugInfoContext) {
    InlinedContext = DebugInfoContext->getInliningInfoForAddress(
        ModuleOffset, getDILineInfoSpecifierFlags(Opts));
  }
  // Make sure there is at least one frame in context.
  if (InlinedContext.getNumberOfFrames() == 0) {
    InlinedContext.addFrame(DILineInfo());
  }
  // Override the function name in lower frame with name from symbol table.
  if (Opts.PrintFunctions && Opts.UseSymbolTable) {
    DIInliningInfo PatchedInlinedContext;
    for (uint32_t i = 0, n = InlinedContext.getNumberOfFrames();
         i < n; i++) {
      DILineInfo LineInfo = InlinedContext.getFrame(i);
      if (i == n - 1) {
        std::string FunctionName;
        uint64_t Start, Size;
        if (getNameFromSymbolTable(SymbolRef::ST_Function,
                                   ModuleOffset, FunctionName, Start, Size)) {
          patchFunctionNameInDILineInfo(FunctionName, LineInfo);
        }
      }
      PatchedInlinedContext.addFrame(LineInfo);
    }
    InlinedContext = PatchedInlinedContext;
  }
  return InlinedContext;
}

bool ModuleInfo::symbolizeData(uint64_t ModuleOffset, std::string &Name,
                               uint64_t &Start, uint64_t &Size) const {
  return getNameFromSymbolTable(SymbolRef::ST_Data,
                                ModuleOffset, Name, Start, Size);
}

static bool error(error_code ec) {
  if (!ec) return false;
  errs() << "LLVMSymbolizer: error reading file: " << ec.message() << ".\n";
  return true;
}

bool ModuleInfo::getNameFromSymbolTable(SymbolRef::Type Type, uint64_t Address,
                                        std::string &Name, uint64_t &Addr,
                                        uint64_t &Size) const {
  assert(Module);
  error_code ec;
  for (symbol_iterator si = Module->begin_symbols(),
                       se = Module->end_symbols();
                       si != se; si.increment(ec)) {
    if (error(ec)) return false;
    uint64_t SymbolAddress;
    uint64_t SymbolSize;
    SymbolRef::Type SymbolType;
    if (error(si->getAddress(SymbolAddress)) ||
        SymbolAddress == UnknownAddressOrSize) continue;
    if (error(si->getSize(SymbolSize)) ||
        SymbolSize == UnknownAddressOrSize) continue;
    if (error(si->getType(SymbolType))) continue;
    // FIXME: If a function has alias, there are two entries in symbol table
    // with same address size. Make sure we choose the correct one.
    if (SymbolAddress <= Address && Address < SymbolAddress + SymbolSize &&
        SymbolType == Type) {
      StringRef SymbolName;
      if (error(si->getName(SymbolName))) continue;
      Name = SymbolName.str();
      Addr = SymbolAddress;
      Size = SymbolSize;
      return true;
    }
  }
  return false;
}

const std::string LLVMSymbolizer::kBadString = "??";

std::string LLVMSymbolizer::symbolizeCode(const std::string &ModuleName,
                                          uint64_t ModuleOffset) {
  ModuleInfo *Info = getOrCreateModuleInfo(ModuleName);
  if (Info == 0)
    return printDILineInfo(DILineInfo());
  if (Opts.PrintInlining) {
    DIInliningInfo InlinedContext = Info->symbolizeInlinedCode(
        ModuleOffset, Opts);
    uint32_t FramesNum = InlinedContext.getNumberOfFrames();
    assert(FramesNum > 0);
    std::string Result;
    for (uint32_t i = 0; i < FramesNum; i++) {
      DILineInfo LineInfo = InlinedContext.getFrame(i);
      Result += printDILineInfo(LineInfo);
    }
    return Result;
  }
  DILineInfo LineInfo = Info->symbolizeCode(ModuleOffset, Opts);
  return printDILineInfo(LineInfo);
}

std::string LLVMSymbolizer::symbolizeData(const std::string &ModuleName,
                                          uint64_t ModuleOffset) {
  std::string Name = kBadString;
  uint64_t Start = 0;
  uint64_t Size = 0;
  if (Opts.UseSymbolTable) {
    if (ModuleInfo *Info = getOrCreateModuleInfo(ModuleName)) {
      if (Info->symbolizeData(ModuleOffset, Name, Start, Size))
        DemangleName(Name);
    }
  }
  std::stringstream ss;
  ss << Name << "\n" << Start << " " << Size << "\n";
  return ss.str();
}

// Returns true if the object endianness is known.
static bool getObjectEndianness(const ObjectFile *Obj,
                                bool &IsLittleEndian) {
  // FIXME: Implement this when libLLVMObject allows to do it easily.
  IsLittleEndian = true;
  return true;
}

static ObjectFile *getObjectFile(const std::string &Path) {
  OwningPtr<MemoryBuffer> Buff;
  MemoryBuffer::getFile(Path, Buff);
  return ObjectFile::createObjectFile(Buff.take());
}

static std::string getDarwinDWARFResourceForModule(const std::string &Path) {
  StringRef Basename = sys::path::filename(Path);
  const std::string &DSymDirectory = Path + ".dSYM";
  SmallString<16> ResourceName = StringRef(DSymDirectory);
  sys::path::append(ResourceName, "Contents", "Resources", "DWARF");
  sys::path::append(ResourceName, Basename);
  return ResourceName.str();
}

ModuleInfo *LLVMSymbolizer::getOrCreateModuleInfo(
    const std::string &ModuleName) {
  ModuleMapTy::iterator I = Modules.find(ModuleName);
  if (I != Modules.end())
    return I->second;

  ObjectFile *Obj = getObjectFile(ModuleName);
  ObjectFile *DbgObj = Obj;
  if (Obj == 0) {
    // Module name doesn't point to a valid object file.
    Modules.insert(make_pair(ModuleName, (ModuleInfo*)0));
    return 0;
  }

  DIContext *Context = 0;
  bool IsLittleEndian;
  if (getObjectEndianness(Obj, IsLittleEndian)) {
    // On Darwin we may find DWARF in separate object file in
    // resource directory.
    if (isa<MachOObjectFile>(Obj)) {
      const std::string &ResourceName = getDarwinDWARFResourceForModule(
          ModuleName);
      ObjectFile *ResourceObj = getObjectFile(ResourceName);
      if (ResourceObj != 0)
        DbgObj = ResourceObj;
    }
    Context = DIContext::getDWARFContext(DbgObj);
    assert(Context);
  }

  ModuleInfo *Info = new ModuleInfo(Obj, Context);
  Modules.insert(make_pair(ModuleName, Info));
  return Info;
}

std::string LLVMSymbolizer::printDILineInfo(DILineInfo LineInfo) const {
  // By default, DILineInfo contains "<invalid>" for function/filename it
  // cannot fetch. We replace it to "??" to make our output closer to addr2line.
  static const std::string kDILineInfoBadString = "<invalid>";
  std::stringstream Result;
  if (Opts.PrintFunctions) {
    std::string FunctionName = LineInfo.getFunctionName();
    if (FunctionName == kDILineInfoBadString)
      FunctionName = kBadString;
    DemangleName(FunctionName);
    Result << FunctionName << "\n";
  }
  std::string Filename = LineInfo.getFileName();
  if (Filename == kDILineInfoBadString)
    Filename = kBadString;
  Result << Filename << ":" << LineInfo.getLine()
                     << ":" << LineInfo.getColumn() << "\n";
  return Result.str();
}

#if !defined(_MSC_VER)
// Assume that __cxa_demangle is provided by libcxxabi (except for Windows).
extern "C" char *__cxa_demangle(const char *mangled_name, char *output_buffer,
                                size_t *length, int *status);
#endif

void LLVMSymbolizer::DemangleName(std::string &Name) const {
#if !defined(_MSC_VER)
  if (!Opts.Demangle)
    return;
  int status = 0;
  char *DemangledName = __cxa_demangle(Name.c_str(), 0, 0, &status);
  if (status != 0)
    return;
  Name = DemangledName;
  free(DemangledName);
#endif
}

}  // namespace symbolize
}  // namespace llvm