third_party/binary_size/src/binary_size_utils.py

# Copyright 2014 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.
"""Common utilities for tools that deal with binary size information.
"""

import logging
import re


def ParseNm(nm_lines):
    """Parse nm output, returning data for all relevant (to binary size)
  symbols and ignoring the rest.

  Args:
      nm_lines: an iterable over lines of nm output.

  Yields:
      (symbol name, symbol type, symbol size, source file path).

      Path may be None if nm couldn't figure out the source file.
  """

    # Match lines with size, symbol, optional location, optional discriminator
    sym_re = re.compile(r'^([0-9a-f]{8,}) '  # address (8+ hex digits)
                        '([0-9a-f]{8,}) '  # size (8+ hex digits)
                        '(.) '  # symbol type, one character
                        '([^\t]+)'  # symbol name, separated from next by tab
                        '(?:\t(.*):[\d\?]+)?.*$')  # location
    # Match lines with addr but no size.
    addr_re = re.compile(r'^[0-9a-f]{8,} (.) ([^\t]+)(?:\t.*)?$')
    # Match lines that don't have an address at all -- typically external symbols.
    noaddr_re = re.compile(r'^ {8,} (.) (.*)$')
    # Match lines with no symbol name, only addr and type
    addr_only_re = re.compile(r'^[0-9a-f]{8,} (.)$')

    seen_lines = set()
    for line in nm_lines:
        line = line.rstrip()
        if line in seen_lines:
            # nm outputs identical lines at times. We don't want to treat
            # those as distinct symbols because that would make no sense.
            continue
        seen_lines.add(line)
        match = sym_re.match(line)
        if match:
            address, size, sym_type, sym = match.groups()[0:4]
            size = int(size, 16)
            if sym_type in ('B', 'b'):
                continue  # skip all BSS for now.
            path = match.group(5)
            yield sym, sym_type, size, path, address
            continue
        match = addr_re.match(line)
        if match:
            # sym_type, sym = match.groups()[0:2]
            continue  # No size == we don't care.
        match = noaddr_re.match(line)
        if match:
            sym_type, sym = match.groups()
            if sym_type in ('U', 'w'):
                continue  # external or weak symbol
        match = addr_only_re.match(line)
        if match:
            continue  # Nothing to do.

        # If we reach this part of the loop, there was something in the
        # line that we didn't expect or recognize.
        logging.warning('nm output parser failed to parse: %s', repr(line))