xref: /external/v8/tools/ll_prof.py

#!/usr/bin/env python
#
# Copyright 2012 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.

import bisect
import collections
import ctypes
import disasm
import mmap
import optparse
import os
import re
import subprocess
import sys
import time


USAGE="""usage: %prog [OPTION]...

Analyses V8 and perf logs to produce profiles.

Perf logs can be collected using a command like:
  $ perf record -R -e cycles -c 10000 -f -i ./d8 bench.js --ll-prof
  # -R: collect all data
  # -e cycles: use cpu-cycles event (run "perf list" for details)
  # -c 10000: write a sample after each 10000 events
  # -f: force output file overwrite
  # -i: limit profiling to our process and the kernel
  # --ll-prof shell flag enables the right V8 logs
This will produce a binary trace file (perf.data) that %prog can analyse.

IMPORTANT:
  The kernel has an internal maximum for events per second, it is 100K by
  default. That's not enough for "-c 10000". Set it to some higher value:
  $ echo 10000000 | sudo tee /proc/sys/kernel/perf_event_max_sample_rate
  You can also make the warning about kernel address maps go away:
  $ echo 0 | sudo tee /proc/sys/kernel/kptr_restrict

We have a convenience script that handles all of the above for you:
  $ tools/run-llprof.sh ./d8 bench.js

Examples:
  # Print flat profile with annotated disassembly for the 10 top
  # symbols. Use default log names.
  $ %prog --disasm-top=10

  # Print flat profile with annotated disassembly for all used symbols.
  # Use default log names and include kernel symbols into analysis.
  $ %prog --disasm-all --kernel

  # Print flat profile. Use custom log names.
  $ %prog --log=foo.log --trace=foo.data
"""


JS_ORIGIN = "js"


class Code(object):
  """Code object."""

  _id = 0
  UNKNOWN = 0
  V8INTERNAL = 1
  FULL_CODEGEN = 2
  OPTIMIZED = 3

  def __init__(self, name, start_address, end_address, origin, origin_offset):
    self.id = Code._id
    Code._id += 1
    self.name = name
    self.other_names = None
    self.start_address = start_address
    self.end_address = end_address
    self.origin = origin
    self.origin_offset = origin_offset
    self.self_ticks = 0
    self.self_ticks_map = None
    self.callee_ticks = None
    if name.startswith("LazyCompile:*"):
      self.codetype = Code.OPTIMIZED
    elif name.startswith("LazyCompile:"):
      self.codetype = Code.FULL_CODEGEN
    elif name.startswith("v8::internal::"):
      self.codetype = Code.V8INTERNAL
    else:
      self.codetype = Code.UNKNOWN

  def AddName(self, name):
    assert self.name != name
    if self.other_names is None:
      self.other_names = [name]
      return
    if not name in self.other_names:
      self.other_names.append(name)

  def FullName(self):
    if self.other_names is None:
      return self.name
    self.other_names.sort()
    return "%s (aka %s)" % (self.name, ", ".join(self.other_names))

  def IsUsed(self):
    return self.self_ticks > 0 or self.callee_ticks is not None

  def Tick(self, pc):
    self.self_ticks += 1
    if self.self_ticks_map is None:
      self.self_ticks_map = collections.defaultdict(lambda: 0)
    offset = pc - self.start_address
    self.self_ticks_map[offset] += 1

  def CalleeTick(self, callee):
    if self.callee_ticks is None:
      self.callee_ticks = collections.defaultdict(lambda: 0)
    self.callee_ticks[callee] += 1

  def PrintAnnotated(self, arch, options):
    if self.self_ticks_map is None:
      ticks_map = []
    else:
      ticks_map = self.self_ticks_map.items()
    # Convert the ticks map to offsets and counts arrays so that later
    # we can do binary search in the offsets array.
    ticks_map.sort(key=lambda t: t[0])
    ticks_offsets = [t[0] for t in ticks_map]
    ticks_counts = [t[1] for t in ticks_map]
    # Get a list of disassembled lines and their addresses.
    lines = self._GetDisasmLines(arch, options)
    if len(lines) == 0:
      return
    # Print annotated lines.
    address = lines[0][0]
    total_count = 0
    for i in xrange(len(lines)):
      start_offset = lines[i][0] - address
      if i == len(lines) - 1:
        end_offset = self.end_address - self.start_address
      else:
        end_offset = lines[i + 1][0] - address
      # Ticks (reported pc values) are not always precise, i.e. not
      # necessarily point at instruction starts. So we have to search
      # for ticks that touch the current instruction line.
      j = bisect.bisect_left(ticks_offsets, end_offset)
      count = 0
      for offset, cnt in reversed(zip(ticks_offsets[:j], ticks_counts[:j])):
        if offset < start_offset:
          break
        count += cnt
      total_count += count
      percent = 100.0 * count / self.self_ticks
      offset = lines[i][0]
      if percent >= 0.01:
        # 5 spaces for tick count
        # 1 space following
        # 1 for '|'
        # 1 space following
        # 6 for the percentage number, incl. the '.'
        # 1 for the '%' sign
        # => 15
        print "%5d | %6.2f%% %x(%d): %s" % (count, percent, offset, offset, lines[i][1])
      else:
        print "%s %x(%d): %s" % (" " * 15, offset, offset, lines[i][1])
    print
    assert total_count == self.self_ticks, \
        "Lost ticks (%d != %d) in %s" % (total_count, self.self_ticks, self)

  def __str__(self):
    return "%s [0x%x, 0x%x) size: %d origin: %s" % (
      self.name,
      self.start_address,
      self.end_address,
      self.end_address - self.start_address,
      self.origin)

  def _GetDisasmLines(self, arch, options):
    if self.origin == JS_ORIGIN:
      inplace = False
      filename = options.log + ".ll"
    else:
      inplace = True
      filename = self.origin
    return disasm.GetDisasmLines(filename,
                                 self.origin_offset,
                                 self.end_address - self.start_address,
                                 arch,
                                 inplace)


class CodePage(object):
  """Group of adjacent code objects."""

  SHIFT = 20  # 1M pages
  SIZE = (1 << SHIFT)
  MASK = ~(SIZE - 1)

  @staticmethod
  def PageAddress(address):
    return address & CodePage.MASK

  @staticmethod
  def PageId(address):
    return address >> CodePage.SHIFT

  @staticmethod
  def PageAddressFromId(id):
    return id << CodePage.SHIFT

  def __init__(self, address):
    self.address = address
    self.code_objects = []

  def Add(self, code):
    self.code_objects.append(code)

  def Remove(self, code):
    self.code_objects.remove(code)

  def Find(self, pc):
    code_objects = self.code_objects
    for i, code in enumerate(code_objects):
      if code.start_address <= pc < code.end_address:
        code_objects[0], code_objects[i] = code, code_objects[0]
        return code
    return None

  def __iter__(self):
    return self.code_objects.__iter__()


class CodeMap(object):
  """Code object map."""

  def __init__(self):
    self.pages = {}
    self.min_address = 1 << 64
    self.max_address = -1

  def Add(self, code, max_pages=-1):
    page_id = CodePage.PageId(code.start_address)
    limit_id = CodePage.PageId(code.end_address + CodePage.SIZE - 1)
    pages = 0
    while page_id < limit_id:
      if max_pages >= 0 and pages > max_pages:
        print >>sys.stderr, \
            "Warning: page limit (%d) reached for %s [%s]" % (
            max_pages, code.name, code.origin)
        break
      if page_id in self.pages:
        page = self.pages[page_id]
      else:
        page = CodePage(CodePage.PageAddressFromId(page_id))
        self.pages[page_id] = page
      page.Add(code)
      page_id += 1
      pages += 1
    self.min_address = min(self.min_address, code.start_address)
    self.max_address = max(self.max_address, code.end_address)

  def Remove(self, code):
    page_id = CodePage.PageId(code.start_address)
    limit_id = CodePage.PageId(code.end_address + CodePage.SIZE - 1)
    removed = False
    while page_id < limit_id:
      if page_id not in self.pages:
        page_id += 1
        continue
      page = self.pages[page_id]
      page.Remove(code)
      removed = True
      page_id += 1
    return removed

  def AllCode(self):
    for page in self.pages.itervalues():
      for code in page:
        if CodePage.PageAddress(code.start_address) == page.address:
          yield code

  def UsedCode(self):
    for code in self.AllCode():
      if code.IsUsed():
        yield code

  def Print(self):
    for code in self.AllCode():
      print code

  def Find(self, pc):
    if pc < self.min_address or pc >= self.max_address:
      return None
    page_id = CodePage.PageId(pc)
    if page_id not in self.pages:
      return None
    return self.pages[page_id].Find(pc)


class CodeInfo(object):
  """Generic info about generated code objects."""

  def __init__(self, arch, header_size):
    self.arch = arch
    self.header_size = header_size


class LogReader(object):
  """V8 low-level (binary) log reader."""

  _ARCH_TO_POINTER_TYPE_MAP = {
    "ia32": ctypes.c_uint32,
    "arm": ctypes.c_uint32,
    "mips": ctypes.c_uint32,
    "x64": ctypes.c_uint64,
    "arm64": ctypes.c_uint64
  }

  _CODE_CREATE_TAG = "C"
  _CODE_MOVE_TAG = "M"
  _CODE_MOVING_GC_TAG = "G"

  def __init__(self, log_name, code_map):
    self.log_file = open(log_name, "r")
    self.log = mmap.mmap(self.log_file.fileno(), 0, mmap.MAP_PRIVATE)
    self.log_pos = 0
    self.code_map = code_map

    self.arch = self.log[:self.log.find("\0")]
    self.log_pos += len(self.arch) + 1
    assert self.arch in LogReader._ARCH_TO_POINTER_TYPE_MAP, \
        "Unsupported architecture %s" % self.arch
    pointer_type = LogReader._ARCH_TO_POINTER_TYPE_MAP[self.arch]

    self.code_create_struct = LogReader._DefineStruct([
        ("name_size", ctypes.c_int32),
        ("code_address", pointer_type),
        ("code_size", ctypes.c_int32)])

    self.code_move_struct = LogReader._DefineStruct([
        ("from_address", pointer_type),
        ("to_address", pointer_type)])

    self.code_delete_struct = LogReader._DefineStruct([
        ("address", pointer_type)])

  def ReadUpToGC(self):
    while self.log_pos < self.log.size():
      tag = self.log[self.log_pos]
      self.log_pos += 1

      if tag == LogReader._CODE_MOVING_GC_TAG:
        return

      if tag == LogReader._CODE_CREATE_TAG:
        event = self.code_create_struct.from_buffer(self.log, self.log_pos)
        self.log_pos += ctypes.sizeof(event)
        start_address = event.code_address
        end_address = start_address + event.code_size
        name = self.log[self.log_pos:self.log_pos + event.name_size]
        origin = JS_ORIGIN
        self.log_pos += event.name_size
        origin_offset = self.log_pos
        self.log_pos += event.code_size
        code = Code(name, start_address, end_address, origin, origin_offset)
        conficting_code = self.code_map.Find(start_address)
        if conficting_code:
          if not (conficting_code.start_address == code.start_address and
            conficting_code.end_address == code.end_address):
            self.code_map.Remove(conficting_code)
          else:
            LogReader._HandleCodeConflict(conficting_code, code)
            # TODO(vitalyr): this warning is too noisy because of our
            # attempts to reconstruct code log from the snapshot.
            # print >>sys.stderr, \
            #     "Warning: Skipping duplicate code log entry %s" % code
            continue
        self.code_map.Add(code)
        continue

      if tag == LogReader._CODE_MOVE_TAG:
        event = self.code_move_struct.from_buffer(self.log, self.log_pos)
        self.log_pos += ctypes.sizeof(event)
        old_start_address = event.from_address
        new_start_address = event.to_address
        if old_start_address == new_start_address:
          # Skip useless code move entries.
          continue
        code = self.code_map.Find(old_start_address)
        if not code:
          print >>sys.stderr, "Warning: Not found %x" % old_start_address
          continue
        assert code.start_address == old_start_address, \
            "Inexact move address %x for %s" % (old_start_address, code)
        self.code_map.Remove(code)
        size = code.end_address - code.start_address
        code.start_address = new_start_address
        code.end_address = new_start_address + size
        self.code_map.Add(code)
        continue

      assert False, "Unknown tag %s" % tag

  def Dispose(self):
    self.log.close()
    self.log_file.close()

  @staticmethod
  def _DefineStruct(fields):
    class Struct(ctypes.Structure):
      _fields_ = fields
    return Struct

  @staticmethod
  def _HandleCodeConflict(old_code, new_code):
    assert (old_code.start_address == new_code.start_address and
            old_code.end_address == new_code.end_address), \
        "Conficting code log entries %s and %s" % (old_code, new_code)
    if old_code.name == new_code.name:
      return
    # Code object may be shared by a few functions. Collect the full
    # set of names.
    old_code.AddName(new_code.name)


class Descriptor(object):
  """Descriptor of a structure in the binary trace log."""

  CTYPE_MAP = {
    "u16": ctypes.c_uint16,
    "u32": ctypes.c_uint32,
    "u64": ctypes.c_uint64
  }

  def __init__(self, fields):
    class TraceItem(ctypes.Structure):
      _fields_ = Descriptor.CtypesFields(fields)

      def __str__(self):
        return ", ".join("%s: %s" % (field, self.__getattribute__(field))
                         for field, _ in TraceItem._fields_)

    self.ctype = TraceItem

  def Read(self, trace, offset):
    return self.ctype.from_buffer(trace, offset)

  @staticmethod
  def CtypesFields(fields):
    return [(field, Descriptor.CTYPE_MAP[format]) for (field, format) in fields]


# Please see http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=tree;f=tools/perf
# for the gory details.


# Reference: struct perf_file_header in kernel/tools/perf/util/header.h
TRACE_HEADER_DESC = Descriptor([
  ("magic", "u64"),
  ("size", "u64"),
  ("attr_size", "u64"),
  ("attrs_offset", "u64"),
  ("attrs_size", "u64"),
  ("data_offset", "u64"),
  ("data_size", "u64"),
  ("event_types_offset", "u64"),
  ("event_types_size", "u64")
])


# Reference: /usr/include/linux/perf_event.h
PERF_EVENT_ATTR_DESC = Descriptor([
  ("type", "u32"),
  ("size", "u32"),
  ("config", "u64"),
  ("sample_period_or_freq", "u64"),
  ("sample_type", "u64"),
  ("read_format", "u64"),
  ("flags", "u64"),
  ("wakeup_events_or_watermark", "u32"),
  ("bp_type", "u32"),
  ("bp_addr", "u64"),
  ("bp_len", "u64")
])


# Reference: /usr/include/linux/perf_event.h
PERF_EVENT_HEADER_DESC = Descriptor([
  ("type", "u32"),
  ("misc", "u16"),
  ("size", "u16")
])


# Reference: kernel/tools/perf/util/event.h
PERF_MMAP_EVENT_BODY_DESC = Descriptor([
  ("pid", "u32"),
  ("tid", "u32"),
  ("addr", "u64"),
  ("len", "u64"),
  ("pgoff", "u64")
])

# Reference: kernel/tools/perf/util/event.h
PERF_MMAP2_EVENT_BODY_DESC = Descriptor([
  ("pid", "u32"),
  ("tid", "u32"),
  ("addr", "u64"),
  ("len", "u64"),
  ("pgoff", "u64"),
  ("maj", "u32"),
  ("min", "u32"),
  ("ino", "u64"),
  ("ino_generation", "u64"),
  ("prot", "u32"),
  ("flags","u32")
])

# perf_event_attr.sample_type bits control the set of
# perf_sample_event fields.
PERF_SAMPLE_IP = 1 << 0
PERF_SAMPLE_TID = 1 << 1
PERF_SAMPLE_TIME = 1 << 2
PERF_SAMPLE_ADDR = 1 << 3
PERF_SAMPLE_READ = 1 << 4
PERF_SAMPLE_CALLCHAIN = 1 << 5
PERF_SAMPLE_ID = 1 << 6
PERF_SAMPLE_CPU = 1 << 7
PERF_SAMPLE_PERIOD = 1 << 8
PERF_SAMPLE_STREAM_ID = 1 << 9
PERF_SAMPLE_RAW = 1 << 10


# Reference: /usr/include/perf_event.h, the comment for PERF_RECORD_SAMPLE.
PERF_SAMPLE_EVENT_BODY_FIELDS = [
  ("ip", "u64", PERF_SAMPLE_IP),
  ("pid", "u32", PERF_SAMPLE_TID),
  ("tid", "u32", PERF_SAMPLE_TID),
  ("time", "u64", PERF_SAMPLE_TIME),
  ("addr", "u64", PERF_SAMPLE_ADDR),
  ("id", "u64", PERF_SAMPLE_ID),
  ("stream_id", "u64", PERF_SAMPLE_STREAM_ID),
  ("cpu", "u32", PERF_SAMPLE_CPU),
  ("res", "u32", PERF_SAMPLE_CPU),
  ("period", "u64", PERF_SAMPLE_PERIOD),
  # Don't want to handle read format that comes after the period and
  # before the callchain and has variable size.
  ("nr", "u64", PERF_SAMPLE_CALLCHAIN)
  # Raw data follows the callchain and is ignored.
]


PERF_SAMPLE_EVENT_IP_FORMAT = "u64"


PERF_RECORD_MMAP = 1
PERF_RECORD_MMAP2 = 10
PERF_RECORD_SAMPLE = 9


class TraceReader(object):
  """Perf (linux-2.6/tools/perf) trace file reader."""

  _TRACE_HEADER_MAGIC = 4993446653023372624

  def __init__(self, trace_name):
    self.trace_file = open(trace_name, "r")
    self.trace = mmap.mmap(self.trace_file.fileno(), 0, mmap.MAP_PRIVATE)
    self.trace_header = TRACE_HEADER_DESC.Read(self.trace, 0)
    if self.trace_header.magic != TraceReader._TRACE_HEADER_MAGIC:
      print >>sys.stderr, "Warning: unsupported trace header magic"
    self.offset = self.trace_header.data_offset
    self.limit = self.trace_header.data_offset + self.trace_header.data_size
    assert self.limit <= self.trace.size(), \
        "Trace data limit exceeds trace file size"
    self.header_size = ctypes.sizeof(PERF_EVENT_HEADER_DESC.ctype)
    assert self.trace_header.attrs_size != 0, \
        "No perf event attributes found in the trace"
    perf_event_attr = PERF_EVENT_ATTR_DESC.Read(self.trace,
                                                self.trace_header.attrs_offset)
    self.sample_event_body_desc = self._SampleEventBodyDesc(
        perf_event_attr.sample_type)
    self.callchain_supported = \
        (perf_event_attr.sample_type & PERF_SAMPLE_CALLCHAIN) != 0
    if self.callchain_supported:
      self.ip_struct = Descriptor.CTYPE_MAP[PERF_SAMPLE_EVENT_IP_FORMAT]
      self.ip_size = ctypes.sizeof(self.ip_struct)

  def ReadEventHeader(self):
    if self.offset >= self.limit:
      return None, 0
    offset = self.offset
    header = PERF_EVENT_HEADER_DESC.Read(self.trace, self.offset)
    self.offset += header.size
    return header, offset

  def ReadMmap(self, header, offset):
    mmap_info = PERF_MMAP_EVENT_BODY_DESC.Read(self.trace,
                                               offset + self.header_size)
    # Read null-terminated filename.
    filename = self.trace[offset + self.header_size + ctypes.sizeof(mmap_info):
                          offset + header.size]
    mmap_info.filename = HOST_ROOT + filename[:filename.find(chr(0))]
    return mmap_info

  def ReadMmap2(self, header, offset):
    mmap_info = PERF_MMAP2_EVENT_BODY_DESC.Read(self.trace,
                                                offset + self.header_size)
    # Read null-terminated filename.
    filename = self.trace[offset + self.header_size + ctypes.sizeof(mmap_info):
                          offset + header.size]
    mmap_info.filename = HOST_ROOT + filename[:filename.find(chr(0))]
    return mmap_info

  def ReadSample(self, header, offset):
    sample = self.sample_event_body_desc.Read(self.trace,
                                              offset + self.header_size)
    if not self.callchain_supported:
      return sample
    sample.ips = []
    offset += self.header_size + ctypes.sizeof(sample)
    for _ in xrange(sample.nr):
      sample.ips.append(
        self.ip_struct.from_buffer(self.trace, offset).value)
      offset += self.ip_size
    return sample

  def Dispose(self):
    self.trace.close()
    self.trace_file.close()

  def _SampleEventBodyDesc(self, sample_type):
    assert (sample_type & PERF_SAMPLE_READ) == 0, \
           "Can't hande read format in samples"
    fields = [(field, format)
              for (field, format, bit) in PERF_SAMPLE_EVENT_BODY_FIELDS
              if (bit & sample_type) != 0]
    return Descriptor(fields)


OBJDUMP_SECTION_HEADER_RE = re.compile(
  r"^\s*\d+\s(\.\S+)\s+[a-f0-9]")
OBJDUMP_SYMBOL_LINE_RE = re.compile(
  r"^([a-f0-9]+)\s(.{7})\s(\S+)\s+([a-f0-9]+)\s+(?:\.hidden\s+)?(.*)$")
OBJDUMP_DYNAMIC_SYMBOLS_START_RE = re.compile(
  r"^DYNAMIC SYMBOL TABLE")
OBJDUMP_SKIP_RE = re.compile(
  r"^.*ld\.so\.cache$")
KERNEL_ALLSYMS_FILE = "/proc/kallsyms"
PERF_KERNEL_ALLSYMS_RE = re.compile(
  r".*kallsyms.*")
KERNEL_ALLSYMS_LINE_RE = re.compile(
  r"^([a-f0-9]+)\s(?:t|T)\s(\S+)$")


class LibraryRepo(object):
  def __init__(self):
    self.infos = []
    self.names = set()
    self.ticks = {}


  def HasDynamicSymbols(self, filename):
    if filename.endswith(".ko"): return False
    process = subprocess.Popen(
      "%s -h %s" % (OBJDUMP_BIN, filename),
      shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    pipe = process.stdout
    try:
      for line in pipe:
        match = OBJDUMP_SECTION_HEADER_RE.match(line)
        if match and match.group(1) == 'dynsym': return True
    finally:
      pipe.close()
    assert process.wait() == 0, "Failed to objdump -h %s" % filename
    return False


  def Load(self, mmap_info, code_map, options):
    # Skip kernel mmaps when requested using the fact that their tid
    # is 0.
    if mmap_info.tid == 0 and not options.kernel:
      return True
    if OBJDUMP_SKIP_RE.match(mmap_info.filename):
      return True
    if PERF_KERNEL_ALLSYMS_RE.match(mmap_info.filename):
      return self._LoadKernelSymbols(code_map)
    self.infos.append(mmap_info)
    mmap_info.ticks = 0
    mmap_info.unique_name = self._UniqueMmapName(mmap_info)
    if not os.path.exists(mmap_info.filename):
      return True
    # Request section headers (-h), symbols (-t), and dynamic symbols
    # (-T) from objdump.
    # Unfortunately, section headers span two lines, so we have to
    # keep the just seen section name (from the first line in each
    # section header) in the after_section variable.
    if self.HasDynamicSymbols(mmap_info.filename):
      dynamic_symbols = "-T"
    else:
      dynamic_symbols = ""
    process = subprocess.Popen(
      "%s -h -t %s -C %s" % (OBJDUMP_BIN, dynamic_symbols, mmap_info.filename),
      shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    pipe = process.stdout
    after_section = None
    code_sections = set()
    reloc_sections = set()
    dynamic = False
    try:
      for line in pipe:
        if after_section:
          if line.find("CODE") != -1:
            code_sections.add(after_section)
          if line.find("RELOC") != -1:
            reloc_sections.add(after_section)
          after_section = None
          continue

        match = OBJDUMP_SECTION_HEADER_RE.match(line)
        if match:
          after_section = match.group(1)
          continue

        if OBJDUMP_DYNAMIC_SYMBOLS_START_RE.match(line):
          dynamic = True
          continue

        match = OBJDUMP_SYMBOL_LINE_RE.match(line)
        if match:
          start_address = int(match.group(1), 16)
          origin_offset = start_address
          flags = match.group(2)
          section = match.group(3)
          if section in code_sections:
            if dynamic or section in reloc_sections:
              start_address += mmap_info.addr
            size = int(match.group(4), 16)
            name = match.group(5)
            origin = mmap_info.filename
            code_map.Add(Code(name, start_address, start_address + size,
                              origin, origin_offset))
    finally:
      pipe.close()
    assert process.wait() == 0, "Failed to objdump %s" % mmap_info.filename

  def Tick(self, pc):
    for i, mmap_info in enumerate(self.infos):
      if mmap_info.addr <= pc < (mmap_info.addr + mmap_info.len):
        mmap_info.ticks += 1
        self.infos[0], self.infos[i] = mmap_info, self.infos[0]
        return True
    return False

  def _UniqueMmapName(self, mmap_info):
    name = mmap_info.filename
    index = 1
    while name in self.names:
      name = "%s-%d" % (mmap_info.filename, index)
      index += 1
    self.names.add(name)
    return name

  def _LoadKernelSymbols(self, code_map):
    if not os.path.exists(KERNEL_ALLSYMS_FILE):
      print >>sys.stderr, "Warning: %s not found" % KERNEL_ALLSYMS_FILE
      return False
    kallsyms = open(KERNEL_ALLSYMS_FILE, "r")
    code = None
    for line in kallsyms:
      match = KERNEL_ALLSYMS_LINE_RE.match(line)
      if match:
        start_address = int(match.group(1), 16)
        end_address = start_address
        name = match.group(2)
        if code:
          code.end_address = start_address
          code_map.Add(code, 16)
        code = Code(name, start_address, end_address, "kernel", 0)
    return True


def PrintReport(code_map, library_repo, arch, ticks, options):
  print "Ticks per symbol:"
  used_code = [code for code in code_map.UsedCode()]
  used_code.sort(key=lambda x: x.self_ticks, reverse=True)
  for i, code in enumerate(used_code):
    code_ticks = code.self_ticks
    print "%10d %5.1f%% %s [%s]" % (code_ticks, 100. * code_ticks / ticks,
                                    code.FullName(), code.origin)
    if options.disasm_all or i < options.disasm_top:
      code.PrintAnnotated(arch, options)
  print
  print "Ticks per library:"
  mmap_infos = [m for m in library_repo.infos if m.ticks > 0]
  mmap_infos.sort(key=lambda m: m.ticks, reverse=True)
  for mmap_info in mmap_infos:
    mmap_ticks = mmap_info.ticks
    print "%10d %5.1f%% %s" % (mmap_ticks, 100. * mmap_ticks / ticks,
                               mmap_info.unique_name)


def PrintDot(code_map, options):
  print "digraph G {"
  for code in code_map.UsedCode():
    if code.self_ticks < 10:
      continue
    print "n%d [shape=box,label=\"%s\"];" % (code.id, code.name)
    if code.callee_ticks:
      for callee, ticks in code.callee_ticks.iteritems():
        print "n%d -> n%d [label=\"%d\"];" % (code.id, callee.id, ticks)
  print "}"


if __name__ == "__main__":
  parser = optparse.OptionParser(USAGE)
  parser.add_option("--log",
                    default="v8.log",
                    help="V8 log file name [default: %default]")
  parser.add_option("--trace",
                    default="perf.data",
                    help="perf trace file name [default: %default]")
  parser.add_option("--kernel",
                    default=False,
                    action="store_true",
                    help="process kernel entries [default: %default]")
  parser.add_option("--disasm-top",
                    default=0,
                    type="int",
                    help=("number of top symbols to disassemble and annotate "
                          "[default: %default]"))
  parser.add_option("--disasm-all",
                    default=False,
                    action="store_true",
                    help=("disassemble and annotate all used symbols "
                          "[default: %default]"))
  parser.add_option("--dot",
                    default=False,
                    action="store_true",
                    help="produce dot output (WIP) [default: %default]")
  parser.add_option("--quiet", "-q",
                    default=False,
                    action="store_true",
                    help="no auxiliary messages [default: %default]")
  parser.add_option("--gc-fake-mmap",
                    default="/tmp/__v8_gc__",
                    help="gc fake mmap file [default: %default]")
  parser.add_option("--objdump",
                    default="/usr/bin/objdump",
                    help="objdump tool to use [default: %default]")
  parser.add_option("--host-root",
                    default="",
                    help="Path to the host root [default: %default]")
  options, args = parser.parse_args()

  if not options.quiet:
    print "V8 log: %s, %s.ll" % (options.log, options.log)
    print "Perf trace file: %s" % options.trace

  V8_GC_FAKE_MMAP = options.gc_fake_mmap
  HOST_ROOT = options.host_root
  if os.path.exists(options.objdump):
    disasm.OBJDUMP_BIN = options.objdump
    OBJDUMP_BIN = options.objdump
  else:
    print "Cannot find %s, falling back to default objdump" % options.objdump

  # Stats.
  events = 0
  ticks = 0
  missed_ticks = 0
  really_missed_ticks = 0
  optimized_ticks = 0
  generated_ticks = 0
  v8_internal_ticks = 0
  mmap_time = 0
  sample_time = 0

  # Initialize the log reader.
  code_map = CodeMap()
  log_reader = LogReader(log_name=options.log + ".ll",
                         code_map=code_map)
  if not options.quiet:
    print "Generated code architecture: %s" % log_reader.arch
    print
    sys.stdout.flush()

  # Process the code and trace logs.
  library_repo = LibraryRepo()
  log_reader.ReadUpToGC()
  trace_reader = TraceReader(options.trace)
  while True:
    header, offset = trace_reader.ReadEventHeader()
    if not header:
      break
    events += 1
    if header.type == PERF_RECORD_MMAP:
      start = time.time()
      mmap_info = trace_reader.ReadMmap(header, offset)
      if mmap_info.filename == HOST_ROOT + V8_GC_FAKE_MMAP:
        log_reader.ReadUpToGC()
      else:
        library_repo.Load(mmap_info, code_map, options)
      mmap_time += time.time() - start
    elif header.type == PERF_RECORD_MMAP2:
      start = time.time()
      mmap_info = trace_reader.ReadMmap2(header, offset)
      if mmap_info.filename == HOST_ROOT + V8_GC_FAKE_MMAP:
        log_reader.ReadUpToGC()
      else:
        library_repo.Load(mmap_info, code_map, options)
      mmap_time += time.time() - start
    elif header.type == PERF_RECORD_SAMPLE:
      ticks += 1
      start = time.time()
      sample = trace_reader.ReadSample(header, offset)
      code = code_map.Find(sample.ip)
      if code:
        code.Tick(sample.ip)
        if code.codetype == Code.OPTIMIZED:
          optimized_ticks += 1
        elif code.codetype == Code.FULL_CODEGEN:
          generated_ticks += 1
        elif code.codetype == Code.V8INTERNAL:
          v8_internal_ticks += 1
      else:
        missed_ticks += 1
      if not library_repo.Tick(sample.ip) and not code:
        really_missed_ticks += 1
      if trace_reader.callchain_supported:
        for ip in sample.ips:
          caller_code = code_map.Find(ip)
          if caller_code:
            if code:
              caller_code.CalleeTick(code)
            code = caller_code
      sample_time += time.time() - start

  if options.dot:
    PrintDot(code_map, options)
  else:
    PrintReport(code_map, library_repo, log_reader.arch, ticks, options)

    if not options.quiet:
      def PrintTicks(number, total, description):
        print("%10d %5.1f%% ticks in %s" %
              (number, 100.0*number/total, description))
      print
      print "Stats:"
      print "%10d total trace events" % events
      print "%10d total ticks" % ticks
      print "%10d ticks not in symbols" % missed_ticks
      unaccounted = "unaccounted ticks"
      if really_missed_ticks > 0:
        unaccounted += " (probably in the kernel, try --kernel)"
      PrintTicks(really_missed_ticks, ticks, unaccounted)
      PrintTicks(optimized_ticks, ticks, "ticks in optimized code")
      PrintTicks(generated_ticks, ticks, "ticks in other lazily compiled code")
      PrintTicks(v8_internal_ticks, ticks, "ticks in v8::internal::*")
      print "%10d total symbols" % len([c for c in code_map.AllCode()])
      print "%10d used symbols" % len([c for c in code_map.UsedCode()])
      print "%9.2fs library processing time" % mmap_time
      print "%9.2fs tick processing time" % sample_time

  log_reader.Dispose()
  trace_reader.Dispose()