Revert "Use llvm symbolizer for stack script."

This reverts commit b6e038a7.

Reason for revert: Broke stack_tool_with_logcat_dump on WebKit Android (Nexus4): https://uberchromegw.corp.google.com/i/chromium.webkit/builders/WebKit%20Android%20%28Nexus4%29/builds/72002

Original change's description:
> Use llvm symbolizer for stack script.
> 
> llvm symbolizer is a more efficient symbolizer than addr2line, objdump,
> etc.
> 
> In this cl, I 1)created a wrapper instance to interact with
> llvm symbolizer, 2)made the stack script to use llvm symbolizer instance,
> and then 3)added llvm symbolizer into isolated inputs.
> 
> Bug: 774267
> Change-Id: I971fb808b97f3a569eb9615f99efa41e3a56f3cb
> Reviewed-on: https://chromium-review.googlesource.com/789376
> Reviewed-by: agrieve <agrieve@chromium.org>
> Reviewed-by: Dirk Pranke <dpranke@chromium.org>
> Commit-Queue: Zhiling Huang <hzl@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#521820}

TBR=dpranke@chromium.org,agrieve@chromium.org,hzl@chromium.org,bpastene@chromium.org,jbudorick@chromium.org

Change-Id: Ieebbcb9527dafd25a0fc74d2826a31162495c86e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 774267
Reviewed-on: https://chromium-review.googlesource.com/809941Reviewed-by: Derek Cheng <imcheng@chromium.org>
Commit-Queue: Derek Cheng <imcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521898}

build/secondary/third_party/android_platform/development/scripts/BUILD.gn

@@ -13,5 +13,9 @@ group("stack_py") {
   sources = _py_files
   data = sources
 
-  data += [ "//third_party/llvm-build/Release+Asserts/bin/llvm-symbolizer" ]
+  data += [
+    "${android_tool_prefix}addr2line",
+    "${android_tool_prefix}objdump",
+    "${android_tool_prefix}c++filt",
+  ]
 }

third_party/android_platform/README.chromium

@@ -40,10 +40,6 @@ Added code to capture java stderr for better handling of native->java crashes.
 Fixed invalid using decl in logging header debug.h
 Only attempt to symbolize with ELF libraries.
 
-Changed the stack script to use llvm symbolizer instead of addr2line,
-objdump, etc, since llvm symbolizer is more efficient in finding
-function names, line numbers etc.
-
 Android relocation packing tool details:
     Copy sources from AOSP bionic/tools/relocation_packer
     Remove scripts that regenerate golden test data (not relevant here)

third_party/android_platform/development/scripts/stack

@@ -31,13 +31,8 @@ import sys
 sys.path.insert(0, os.path.join(os.path.dirname(__file__),
                                 os.pardir, os.pardir, os.pardir, os.pardir,
                                 'build', 'android'))
-
 from pylib import constants
 
-sys.path.insert(0, os.path.join(os.path.dirname(__file__),
-                                os.pardir, os.pardir, os.pardir, os.pardir,
-                                'tools', 'python'))
-import llvm_symbolizer
 
 DEFAULT_SYMROOT='/tmp/symbols'
 # From: https://source.android.com/source/build-numbers.html
@@ -230,12 +225,10 @@ def main(argv):
   print ("Reading Android symbols from: "
          + os.path.normpath(symbol.SYMBOLS_DIR))
   chrome_search_path = symbol.GetLibrarySearchPaths()
-
-  with llvm_symbolizer.LLVMSymbolizer() as symbolizer:
-    print ("Searching for Chrome symbols from within: "
-           + ':'.join((os.path.normpath(d) for d in chrome_search_path)))
-    stack_core.ConvertTrace(lines, load_vaddrs, more_info, fallback_monochrome,
-                            arch_defined, symbolizer)
+  print ("Searching for Chrome symbols from within: "
+         + ':'.join((os.path.normpath(d) for d in chrome_search_path)))
+  stack_core.ConvertTrace(lines, load_vaddrs, more_info, fallback_monochrome,
+                          arch_defined)
 
   if rootdir:
     # be a good citizen and clean up...os.rmdir and os.removedirs() don't work

third_party/android_platform/development/scripts/stack_core.py

@@ -158,7 +158,7 @@ def PrintDivider():
   print
   print '-----------------------------------------------------\n'
 
-def ConvertTrace(lines, load_vaddrs, more_info, fallback_monochrome, arch_defined, llvm_symbolizer):
+def ConvertTrace(lines, load_vaddrs, more_info, fallback_monochrome, arch_defined):
   """Convert strings containing native crash to a stack."""
   InitWidthRelatedLineMatchers()
 
@@ -189,7 +189,7 @@ def ConvertTrace(lines, load_vaddrs, more_info, fallback_monochrome, arch_define
       print ('Find ABI:' + arch)
       symbol.ARCH = arch
 
-  ResolveCrashSymbol(list(useful_log), more_info, llvm_symbolizer)
+  ResolveCrashSymbol(list(useful_log), more_info)
   end = time.time()
   logging.debug('Finished resolving symbols. Elapsed time: %.4fs',
                 (end - start))
@@ -304,7 +304,7 @@ class PreProcessLog:
         useful_log.append(line)
     return useful_log, self._so_dirs
 
-def ResolveCrashSymbol(lines, more_info, llvm_symbolizer):
+def ResolveCrashSymbol(lines, more_info):
   """Convert unicode strings which contains native crash to a stack
   """
 
@@ -313,6 +313,39 @@ def ResolveCrashSymbol(lines, more_info, llvm_symbolizer):
   last_frame = -1
   pid = -1
 
+  # It is faster to get symbol information with a single call rather than with
+  # separate calls for each line. Since symbol.SymbolInformation caches results,
+  # we can extract all the addresses that we will want symbol information for
+  # from the log and call symbol.SymbolInformation so that the results are
+  # cached in the following lookups.
+  code_addresses = {}
+
+  # Collects all java exception lines, keyed by pid for later output during
+  # native crash handling.
+  java_stderr_by_pid = {}
+  for line in lines:
+    lib, address = None, None
+
+    match = _TRACE_LINE.match(line) or _DEBUG_TRACE_LINE.match(line)
+    if match:
+      address, lib = match.group('address', 'lib')
+
+    match = _VALUE_LINE.match(line)
+    if match and not _CODE_LINE.match(line):
+      (_0, _1, address, lib, _2, _3) = match.groups()
+
+    if lib:
+      code_addresses.setdefault(lib, set()).add(address)
+
+    java_stderr_match = _JAVA_STDERR_LINE.search(line)
+    if java_stderr_match:
+      pid, msg = java_stderr_match.groups()
+      java_stderr_by_pid.setdefault(pid, []).append(msg)
+
+  for lib in code_addresses:
+    symbol.SymbolInformationForSet(
+        symbol.TranslateLibPath(lib), code_addresses[lib], more_info)
+
   for line in lines:
     # AndroidFeedback adds zero width spaces into its crash reports. These
     # should be removed or the regular expresssions will fail to match.
@@ -377,19 +410,25 @@ def ResolveCrashSymbol(lines, more_info, llvm_symbolizer):
         logging.debug('Identified lib: %s' % area)
         # If a calls b which further calls c and c is inlined to b, we want to
         # display "a -> b -> c" in the stack trace instead of just "a -> c"
-        # To use llvm symbolizer, the hexadecimal address has to start with 0x.
-        info = llvm_symbolizer.GetSymbolInformation(
-            os.path.join(symbol.SYMBOLS_DIR, symbol.TranslateLibPath(area)),
-            '0x' + code_addr)
+        info = symbol.SymbolInformation(area, code_addr, more_info)
         logging.debug('symbol information: %s' % info)
         nest_count = len(info) - 1
-        for source_symbol, source_location in info:
+        for (source_symbol, source_location, object_symbol_with_offset) in info:
+          if not source_symbol:
+            if symbol_present:
+              source_symbol = symbol.CallCppFilt(symbol_name)
+            else:
+              source_symbol = UNKNOWN
+          if not source_location:
+            source_location = area
           if nest_count > 0:
             nest_count = nest_count - 1
             trace_lines.append(('v------>', source_symbol, source_location))
           else:
+            if not object_symbol_with_offset:
+              object_symbol_with_offset = source_symbol
             trace_lines.append((code_addr,
-                                source_symbol,
+                                object_symbol_with_offset,
                                 source_location))
     match = _VALUE_LINE.match(line)
     if match:
@@ -397,14 +436,20 @@ def ResolveCrashSymbol(lines, more_info, llvm_symbolizer):
       if area == UNKNOWN or area == HEAP or area == STACK or not area:
         value_lines.append((addr, value, '', area))
       else:
-        info = llvm_symbolizer.GetSymbolInformation(
-            os.path.join(symbol.SYMBOLS_DIR, symbol.TranslateLibPath(area)),
-            '0x' + code_addr)
-        source_symbol, source_location = info.pop()
-
+        info = symbol.SymbolInformation(area, value, more_info)
+        (source_symbol, source_location, object_symbol_with_offset) = info.pop()
+        if not source_symbol:
+          if symbol_present:
+            source_symbol = symbol.CallCppFilt(symbol_name)
+          else:
+            source_symbol = UNKNOWN
+        if not source_location:
+          source_location = area
+        if not object_symbol_with_offset:
+          object_symbol_with_offset = source_symbol
         value_lines.append((addr,
                             value,
-                            source_symbol,
+                            object_symbol_with_offset,
                             source_location))
 
   java_lines = []

third_party/android_platform/development/scripts/symbol.py

@@ -69,6 +69,91 @@ def Uname():
     return "linux-x86"
   return uname
 
+def ToolPath(tool, toolchain_info=None):
+  """Return a full qualified path to the specified tool"""
+  # ToolPath looks for the tools in the completely incorrect directory.
+  # This looks in the checked in android_tools.
+  if ARCH == "arm":
+    toolchain_source = "arm-linux-androideabi-4.9"
+    toolchain_prefix = "arm-linux-androideabi"
+    ndk = "ndk"
+  elif ARCH == "arm64":
+    toolchain_source = "aarch64-linux-android-4.9"
+    toolchain_prefix = "aarch64-linux-android"
+    ndk = "ndk"
+  elif ARCH == "x86":
+    toolchain_source = "x86-4.9"
+    toolchain_prefix = "i686-linux-android"
+    ndk = "ndk"
+  elif ARCH == "x86_64" or ARCH == "x64":
+    toolchain_source = "x86_64-4.9"
+    toolchain_prefix = "x86_64-linux-android"
+    ndk = "ndk"
+  elif ARCH == "mips":
+    toolchain_source = "mipsel-linux-android-4.9"
+    toolchain_prefix = "mipsel-linux-android"
+    ndk = "ndk"
+  else:
+    raise Exception("Could not find tool chain for " + ARCH)
+
+  toolchain_subdir = (
+      "third_party/android_tools/%s/toolchains/%s/prebuilt/linux-x86_64/bin" %
+       (ndk, toolchain_source))
+
+  return os.path.join(CHROME_SRC,
+                      toolchain_subdir,
+                      toolchain_prefix + "-" + tool)
+
+def FindToolchain():
+  """Look for the latest available toolchain
+
+  Args:
+    None
+
+  Returns:
+    A pair of strings containing toolchain label and target prefix.
+  """
+  global TOOLCHAIN_INFO
+  if TOOLCHAIN_INFO is not None:
+    return TOOLCHAIN_INFO
+
+  ## Known toolchains, newer ones in the front.
+  gcc_version = "4.9"
+  if ARCH == "arm64":
+    known_toolchains = [
+      ("aarch64-linux-android-" + gcc_version, "aarch64", "aarch64-linux-android")
+    ]
+  elif ARCH == "arm":
+    known_toolchains = [
+      ("arm-linux-androideabi-" + gcc_version, "arm", "arm-linux-androideabi")
+    ]
+  elif ARCH =="x86":
+    known_toolchains = [
+      ("x86-" + gcc_version, "x86", "i686-linux-android")
+    ]
+  elif ARCH =="x86_64" or ARCH =="x64":
+    known_toolchains = [
+      ("x86_64-" + gcc_version, "x86_64", "x86_64-linux-android")
+    ]
+  elif ARCH == "mips":
+    known_toolchains = [
+      ("mipsel-linux-android-" + gcc_version, "mips", "mipsel-linux-android")
+    ]
+  else:
+    known_toolchains = []
+
+  logging.debug('FindToolcahin: known_toolchains=%s' % known_toolchains)
+  # Look for addr2line to check for valid toolchain path.
+  for (label, platform, target) in known_toolchains:
+    toolchain_info = (label, platform, target);
+    if os.path.exists(ToolPath("addr2line", toolchain_info)):
+      TOOLCHAIN_INFO = toolchain_info
+      print ("Using toolchain from: "
+             + os.path.normpath(ToolPath("", TOOLCHAIN_INFO)))
+      return toolchain_info
+
+  raise Exception("Could not find tool chain")
+
 def GetAapt():
   """Returns the path to aapt.
 
@@ -279,7 +364,260 @@ def TranslateLibPath(lib):
 
   library_path = os.path.relpath(candidate_libraries[0], SYMBOLS_DIR)
   logging.debug('TranslateLibPath: library_path=%s' % library_path)
-  return library_path
+  return '/' + library_path
+
+def SymbolInformation(lib, addr, get_detailed_info):
+  """Look up symbol information about an address.
+
+  Args:
+    lib: library (or executable) pathname containing symbols
+    addr: string hexidecimal address
+
+  Returns:
+    A list of the form [(source_symbol, source_location,
+    object_symbol_with_offset)].
+
+    If the function has been inlined then the list may contain
+    more than one element with the symbols for the most deeply
+    nested inlined location appearing first.  The list is
+    always non-empty, even if no information is available.
+
+    Usually you want to display the source_location and
+    object_symbol_with_offset from the last element in the list.
+  """
+  lib = TranslateLibPath(lib)
+  info = SymbolInformationForSet(lib, set([addr]), get_detailed_info)
+  return (info and info.get(addr)) or [(None, None, None)]
+
+
+def SymbolInformationForSet(lib, unique_addrs, get_detailed_info):
+  """Look up symbol information for a set of addresses from the given library.
+
+  Args:
+    lib: library (or executable) pathname containing symbols
+    unique_addrs: set of hexidecimal addresses
+
+  Returns:
+    A dictionary of the form {addr: [(source_symbol, source_location,
+    object_symbol_with_offset)]} where each address has a list of
+    associated symbols and locations.  The list is always non-empty.
+
+    If the function has been inlined then the list may contain
+    more than one element with the symbols for the most deeply
+    nested inlined location appearing first.  The list is
+    always non-empty, even if no information is available.
+
+    Usually you want to display the source_location and
+    object_symbol_with_offset from the last element in the list.
+  """
+  if not lib:
+    return None
+
+  addr_to_line = CallAddr2LineForSet(lib, unique_addrs)
+  if not addr_to_line:
+    return None
+
+  if get_detailed_info:
+    addr_to_objdump = CallObjdumpForSet(lib, unique_addrs)
+    if not addr_to_objdump:
+      return None
+  else:
+    addr_to_objdump = dict((addr, ("", 0)) for addr in unique_addrs)
+
+  result = {}
+  for addr in unique_addrs:
+    source_info = addr_to_line.get(addr)
+    if not source_info:
+      source_info = [(None, None)]
+    if addr in addr_to_objdump:
+      (object_symbol, object_offset) = addr_to_objdump.get(addr)
+      object_symbol_with_offset = FormatSymbolWithOffset(object_symbol,
+                                                         object_offset)
+    else:
+      object_symbol_with_offset = None
+    result[addr] = [(source_symbol, source_location, object_symbol_with_offset)
+        for (source_symbol, source_location) in source_info]
+
+  return result
+
+
+class MemoizedForSet(object):
+  def __init__(self, fn):
+    self.fn = fn
+    self.cache = {}
+
+  def __call__(self, lib, unique_addrs):
+    lib_cache = self.cache.setdefault(lib, {})
+
+    no_cache = filter(lambda x: x not in lib_cache, unique_addrs)
+    if no_cache:
+      lib_cache.update((k, None) for k in no_cache)
+      result = self.fn(lib, no_cache)
+      if result:
+        lib_cache.update(result)
+
+    return dict((k, lib_cache[k]) for k in unique_addrs if lib_cache[k])
+
+
+@MemoizedForSet
+def CallAddr2LineForSet(lib, unique_addrs):
+  """Look up line and symbol information for a set of addresses.
+
+  Args:
+    lib: library (or executable) pathname containing symbols
+    unique_addrs: set of string hexidecimal addresses look up.
+
+  Returns:
+    A dictionary of the form {addr: [(symbol, file:line)]} where
+    each address has a list of associated symbols and locations
+    or an empty list if no symbol information was found.
+
+    If the function has been inlined then the list may contain
+    more than one element with the symbols for the most deeply
+    nested inlined location appearing first.
+  """
+  if not lib:
+    return None
+
+  symbols = SYMBOLS_DIR + lib
+  if not os.path.splitext(symbols)[1] in ['', '.so', '.apk']:
+    return None
+
+  if not os.path.isfile(symbols):
+    return None
+
+  addrs = sorted(unique_addrs)
+  result = {}
+
+  def _Callback(sym, addr):
+    records = []
+    while sym:  # Traverse all the inlines following the |inlined_by| chain.
+      if sym.source_path and sym.source_line:
+        location = '%s:%d' % (sym.source_path, sym.source_line)
+      else:
+        location = None
+      records += [(sym.name, location)]
+      sym = sym.inlined_by
+    result[addr] = records
+
+  (label, platform, target) = FindToolchain()
+  symbolizer = elf_symbolizer.ELFSymbolizer(
+      elf_file_path=symbols,
+      addr2line_path=ToolPath("addr2line"),
+      callback=_Callback,
+      inlines=True)
+
+  for addr in addrs:
+    symbolizer.SymbolizeAsync(int(addr, 16), addr)
+  symbolizer.Join()
+  return result
+
+
+def StripPC(addr):
+  """Strips the Thumb bit a program counter address when appropriate.
+
+  Args:
+    addr: the program counter address
+
+  Returns:
+    The stripped program counter address.
+  """
+  global ARCH
+
+  if ARCH == "arm":
+    return addr & ~1
+  return addr
+
+@MemoizedForSet
+def CallObjdumpForSet(lib, unique_addrs):
+  """Use objdump to find out the names of the containing functions.
+
+  Args:
+    lib: library (or executable) pathname containing symbols
+    unique_addrs: set of string hexidecimal addresses to find the functions for.
+
+  Returns:
+    A dictionary of the form {addr: (string symbol, offset)}.
+  """
+  if not lib:
+    return None
+
+  symbols = SYMBOLS_DIR + lib
+  if not os.path.exists(symbols):
+    return None
+
+  symbols = SYMBOLS_DIR + lib
+  if not os.path.exists(symbols):
+    return None
+
+  result = {}
+
+  # Function lines look like:
+  #   000177b0 <android::IBinder::~IBinder()+0x2c>:
+  # We pull out the address and function first. Then we check for an optional
+  # offset. This is tricky due to functions that look like "operator+(..)+0x2c"
+  func_regexp = re.compile("(^[a-f0-9]*) \<(.*)\>:$")
+  offset_regexp = re.compile("(.*)\+0x([a-f0-9]*)")
+
+  # A disassembly line looks like:
+  #   177b2:  b510        push  {r4, lr}
+  asm_regexp = re.compile("(^[ a-f0-9]*):[ a-f0-0]*.*$")
+
+  for target_addr in unique_addrs:
+    start_addr_dec = str(StripPC(int(target_addr, 16)))
+    stop_addr_dec = str(StripPC(int(target_addr, 16)) + 8)
+    cmd = [ToolPath("objdump"),
+           "--section=.text",
+           "--demangle",
+           "--disassemble",
+           "--start-address=" + start_addr_dec,
+           "--stop-address=" + stop_addr_dec,
+           symbols]
+
+    current_symbol = None    # The current function symbol in the disassembly.
+    current_symbol_addr = 0  # The address of the current function.
+
+    stream = subprocess.Popen(cmd, stdout=subprocess.PIPE).stdout
+    for line in stream:
+      # Is it a function line like:
+      #   000177b0 <android::IBinder::~IBinder()>:
+      components = func_regexp.match(line)
+      if components:
+        # This is a new function, so record the current function and its address.
+        current_symbol_addr = int(components.group(1), 16)
+        current_symbol = components.group(2)
+
+        # Does it have an optional offset like: "foo(..)+0x2c"?
+        components = offset_regexp.match(current_symbol)
+        if components:
+          current_symbol = components.group(1)
+          offset = components.group(2)
+          if offset:
+            current_symbol_addr -= int(offset, 16)
+
+      # Is it an disassembly line like:
+      #   177b2:  b510        push  {r4, lr}
+      components = asm_regexp.match(line)
+      if components:
+        addr = components.group(1)
+        i_addr = int(addr, 16)
+        i_target = StripPC(int(target_addr, 16))
+        if i_addr == i_target:
+          result[target_addr] = (current_symbol, i_target - current_symbol_addr)
+    stream.close()
+
+  return result
+
+
+def CallCppFilt(mangled_symbol):
+  cmd = [ToolPath("c++filt")]
+  process = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
+  process.stdin.write(mangled_symbol)
+  process.stdin.write("\n")
+  process.stdin.close()
+  demangled_symbol = process.stdout.readline().strip()
+  process.stdout.close()
+  return demangled_symbol
 
 def FormatSymbolWithOffset(symbol, offset):
   if offset == 0:

tools/python/llvm_symbolizer.py

-# Copyright 2017 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.
-
-import logging
-import os
-import re
-import subprocess
-import threading
-
-_CHROME_SRC = os.path.join(os.path.dirname(__file__), os.pardir, os.pardir)
-_LLVM_SYMBOLIZER_PATH = os.path.join(
-    _CHROME_SRC, 'third_party', 'llvm-build', 'Release+Asserts', 'bin',
-    'llvm-symbolizer')
-
-_BINARY = re.compile(r'0b[0,1]+')
-_HEX = re.compile(r'0x[0-9,a-e]+')
-_OCTAL = re.compile(r'0[0-7]+')
-
-_UNKNOWN = '<UNKNOWN>'
-
-
-def _CheckValidAddr(addr):
-  """
-  Check whether the addr is valid input to llvm symbolizer.
-  Valid addr has to be octal, binary, or hex number.
-
-  Args:
-    addr: addr to be entered to llvm symbolizer.
-
-  Returns:
-    whether the addr is valid input to llvm symbolizer.
-  """
-  return _HEX.match(addr) or _OCTAL.match(addr) or _BINARY.match(addr)
-
-
-class LLVMSymbolizer(object):
-  def __init__(self):
-    """Create a LLVMSymbolizer instance that interacts with the llvm symbolizer.
-
-    The purpose of the LLVMSymbolizer is to get function names and line
-    numbers of an address from the symbols library.
-    """
-    self._llvm_symbolizer_subprocess = None
-    # Allow only one thread to call GetSymbolInformation at a time.
-    self._lock = threading.Lock()
-
-  def Start(self):
-    """Start the llvm symbolizer subprocess.
-
-    Create a subprocess of the llvm symbolizer executable, which will be used
-    to retrieve function names etc.
-    """
-    if os.path.isfile(_LLVM_SYMBOLIZER_PATH):
-      self._llvm_symbolizer_subprocess = subprocess.Popen(
-        [_LLVM_SYMBOLIZER_PATH], stdout=subprocess.PIPE, stdin=subprocess.PIPE)
-    else:
-      logging.error('Cannot find llvm_symbolizer here: %s.' %
-                    _LLVM_SYMBOLIZER_PATH)
-      self._llvm_symbolizer_subprocess = None
-
-  def Close(self):
-    """Close the llvm symbolizer subprocess.
-
-    Close the subprocess by closing stdin, stdout and killing the subprocess.
-    """
-    with self._lock:
-      if self._llvm_symbolizer_subprocess:
-        self._llvm_symbolizer_subprocess.kill()
-        self._llvm_symbolizer_subprocess = None
-
-  def __enter__(self):
-    """Start the llvm symbolizer subprocess."""
-    self.Start()
-    return self
-
-  def __exit__(self, exc_type, exc_val, exc_tb):
-    """Close the llvm symbolizer subprocess."""
-    self.Close()
-
-  def GetSymbolInformation(self, lib, addr):
-    """Return the corresponding function names and line numbers.
-
-    Args:
-      lib: library to search for info.
-      addr: address to look for info.
-
-    Returns:
-      A list of (function name, line numbers) tuple.
-    """
-    if (self._llvm_symbolizer_subprocess is None or not lib
-        or not _CheckValidAddr(addr) or not os.path.isfile(lib)):
-      return [(_UNKNOWN, lib)]
-
-    with self._lock:
-      self._llvm_symbolizer_subprocess.stdin.write('%s %s\n' % (lib, addr))
-      self._llvm_symbolizer_subprocess.stdin.flush()
-
-      result = []
-      # Read till see new line, which is a symbol of end of output.
-      # One line of function name is always followed by one line of line number.
-      while True:
-        line = self._llvm_symbolizer_subprocess.stdout.readline()
-        if line != '\n':
-          line_numbers = self._llvm_symbolizer_subprocess.stdout.readline()
-          result.append(
-            (line[:-1],
-             line_numbers[:-1]))
-        else:
-          return result