SuperSize: Teach it about thin archives

"supersize archive" would crash upon encountering a .a file that was
linked as a "thin archive" (where the actual .o files are not embedded).

This fixes the tool by transforming all foo.a(bar.o) paths into their
external object paths.

Also adds main() functions for ninja_parser.py for debugging.

Bug: 830843
Change-Id: Iddc374565b8e94a4a89b2faa343256ea2d9f569e
Reviewed-on: https://chromium-review.googlesource.com/1007317
Commit-Queue: agrieve <agrieve@chromium.org>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550141}

tools/binary_size/README.md

@@ -85,26 +85,28 @@ between milestones.
 ##### Native Symbols
 
 1. Symbol list is Extracted from linker `.map` file.
-   * Map files contain some unique pieces of information compared to `nm` output,
-      such as `** merge strings` entries, and some unnamed symbols (which
-      although unnamed, contain the `.o` path).
+   * Map files contain some unique pieces of information compared to `nm`
+      output, such as `** merge strings` entries, and some unnamed symbols
+      (which although unnamed, contain the `.o` path).
 1. `.o` files are mapped to `.cc` files by parsing `.ninja` files.
-   * This means that `.h` files are never listed as sources. No information about
-     inlined symbols is gathered.
-1. Symbol aliases (when multiple symbols share an address) are collected from
-   debug information via `nm elf-file`.
-   * Aliases are created by identical code folding (linker optimization).
+   * This means that `.h` files are never listed as sources. No information
+     about inlined symbols is gathered.
+1. `** merge strings` symbols are further broken down into individual string
+   literal symbols. This is done by reading string literals from `.o` files, and
+   then searching for them within the `** merge strings` sections.
+1. Symbol aliases:
    * Aliases have the same address and size, but report their `.pss` as
       `.size / .num_aliases`.
-1. `** merge strings` symbols are further broken down into individual string
-  literal symbols. This is done by reading string literals from `.o` files, and
-  then searching for them within the `** merge strings` sections.
-1. "Shared symbols" are those that are owned by multiple `.o` files. These include
-  inline functions defined in `.h` files, and string literals that are de-duped
-  at link-time. Shared symbols are normally represented using one symbol alias
-  per path, but are sometimes collapsed into a single symbol where the path is
-  set to `{shared}/$SYMBOL_COUNT`. This collapsing is done only for symbols owned
-  by a large number of paths.
+   * Type 1: Different names. Caused by identical code folding.
+     * These are collected from debug information via `nm elf-file`.
+   * Type 2: Same names, different paths. Caused by inline functions defined in
+     `.h` files.
+     * These are collected by running `nm` on each `.o` file.
+     * Normally represented using one alias per path, but are sometimes
+       collapsed into a single symbol with a path of `{shared}/$SYMBOL_COUNT`.
+       This collapsing is done only for symbols owned by a large number of paths.
+   * Type 3: String literals that are de-duped at link-time.
+     * These are found as part of the string literal extraction process.
 
 ##### Pak Symbols
 

tools/binary_size/libsupersize/ar.py

+#!/usr/bin/env python
+# Copyright 2018 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.
+
+"""Logic for reading .a files."""
+
+from __future__ import print_function
+
+import argparse
+import logging
+import os
+
+
+def IsThinArchive(path):
+  """Returns whether the given .a is a thin archive."""
+  with open(path, 'rb') as f:
+    return f.read(8) == '!<thin>\n'
+
+
+def CreateThinObjectPath(archive_path, subpath):
+  """Given the .a path and .o subpath, returns the .o path."""
+  # .o subpaths in thin archives are relative to the directory of the .a.
+  parent_path = os.path.dirname(archive_path)
+  return os.path.normpath(os.path.join(parent_path, subpath))
+
+
+def IterArchiveChunks(path):
+  """For each .o embedded in the given .a file, yields (foo.o, foo_contents)."""
+  # File format reference:
+  # https://github.com/pathscale/binutils/blob/master/gold/archive.cc
+  with open(path, 'rb') as f:
+    header = f.read(8)
+    is_thin = header == '!<thin>\n'
+    if not is_thin and header != '!<arch>\n':
+      raise Exception('Invalid .a: ' + path)
+
+    def read_payload(size):
+      ret = f.read(size)
+      # Entries are 2-byte aligned.
+      if size & 1 != 0:
+        f.read(1)
+      return ret
+
+    while True:
+      entry = f.read(60)
+      if not entry:
+        return
+      entry_name = entry[:16].rstrip()
+      entry_size = int(entry[48:58].rstrip())
+
+      if entry_name in ('', '/', '//', '/SYM64/'):
+        payload = read_payload(entry_size)
+        # Metadata sections we don't care about.
+        if entry_name == '//':
+          name_list = payload
+        continue
+
+      if entry_name[0] == '/':
+        # Name is specified as location in name table.
+        # E.g.: /123
+        name_offset = int(entry_name[1:])
+        # String table enties are delimited by \n (e.g. "browser.o/\n").
+        end_idx = name_list.index('\n', name_offset)
+        entry_name = name_list[name_offset:end_idx]
+      else:
+        # Name specified inline with spaces for padding (e.g. "browser.o/    ").
+        entry_name = entry_name.rstrip()
+
+      # Although entry_size exists for thin archives, no data exists in the .a.
+      entry_data = None if is_thin else read_payload(entry_size)
+      yield entry_name.rstrip('/'), entry_data
+
+
+def ExpandThinArchives(paths, output_directory):
+  """Expands all thin archives found in |paths| into .o paths.
+
+  Args:
+    paths: List of paths relative to |output_directory|.
+    output_directory: Output directory.
+
+  Returns:
+    * A new list of paths with all thin archives replaced by .o paths.
+    * A set of all .a paths that were thin archives.
+  """
+  expanded_paths = []
+  thin_paths = set()
+  num_archives = 0
+  for path in paths:
+    if not path.endswith('.a'):
+      expanded_paths.append(path)
+      continue
+    num_archives += 1
+    abs_path = os.path.join(output_directory, path)
+    if not IsThinArchive(abs_path):
+      expanded_paths.append(path)
+      continue
+
+    thin_paths.add(path)
+    # Thin archive.
+    for subpath, _ in IterArchiveChunks(abs_path):
+      expanded_paths.append(CreateThinObjectPath(path, subpath))
+
+  logging.info('%d of %d .a files were thin archives',
+               len(thin_paths), num_archives)
+  return expanded_paths, thin_paths
+
+
+def CreateThinObjectPath(archive_path, subpath):
+  parent_path = os.path.dirname(archive_path)
+  return os.path.normpath(os.path.join(parent_path, subpath))
+
+
+def main():
+  parser = argparse.ArgumentParser()
+  parser.add_argument('ar_path')
+  parser.add_argument('--expand-thin', action='store_true')
+  parser.add_argument('--output-directory', default='.')
+  args = parser.parse_args()
+
+  if args.expand_thin:
+    expanded = ExpandThinArchives([args.ar_path], args.output_directory)[0]
+    print('\n'.join(expanded))
+  else:
+    for name, payload in IterArchiveChunks(args.ar_path):
+      print('{}: size={}'.format(name, len(payload) if payload else '<thin>'))
+
+
+if __name__ == '__main__':
+  main()

tools/binary_size/libsupersize/archive.py

@@ -20,6 +20,7 @@ import tempfile
 import zipfile
 
 import apkanalyzer
+import ar
 import concurrent
 import demangle
 import describe
@@ -35,6 +36,16 @@ sys.path.insert(1, os.path.join(path_util.SRC_ROOT, 'tools', 'grit'))
 from grit.format import data_pack
 
 
+# Holds computation state that is live only when an output directory exists.
+_OutputDirectoryContext = collections.namedtuple('_OutputDirectoryContext', [
+    'elf_object_paths',  # Only when elf_path is also provided.
+    'known_inputs',  # Only when elf_path is also provided.
+    'output_directory',
+    'source_mapper',
+    'thin_archives',
+])
+
+
 # Tunable "knobs" for CreateSectionSizesAndSymbols().
 class SectionSizeKnobs(object):
   def __init__(self):
@@ -190,8 +201,9 @@ def _NormalizeObjectPath(path):
     # Convert ../../third_party/... -> third_party/...
     path = path[6:]
   if path.endswith(')'):
-    # Convert foo/bar.a(baz.o) -> foo/bar.a/baz.o
-    start_idx = path.index('(')
+    # Convert foo/bar.a(baz.o) -> foo/bar.a/baz.o so that hierarchical
+    # breakdowns consider the .o part to be a separate node.
+    start_idx = path.rindex('(')
     path = os.path.join(path[:start_idx], path[start_idx + 1:-1])
   return path
 
@@ -373,17 +385,16 @@ def _AssignNmAliasPathsAndCreatePathAliases(raw_symbols, object_paths_by_name):
   return ret
 
 
-def _DiscoverMissedObjectPaths(raw_symbols, elf_object_paths):
+def _DiscoverMissedObjectPaths(raw_symbols, known_inputs):
   # Missing object paths are caused by .a files added by -l flags, which are not
   # listed as explicit inputs within .ninja rules.
-  parsed_inputs = set(elf_object_paths)
   missed_inputs = set()
   for symbol in raw_symbols:
     path = symbol.object_path
     if path.endswith(')'):
       # Convert foo/bar.a(baz.o) -> foo/bar.a
-      path = path[:path.index('(')]
-    if path and path not in parsed_inputs:
+      path = path[:path.rindex('(')]
+    if path and path not in known_inputs:
       missed_inputs.add(path)
   return missed_inputs
 
@@ -608,9 +619,21 @@ def CreateMetadata(map_path, elf_path, apk_path, tool_prefix, output_directory):
   return metadata
 
 
-def _ParseElfInfo(map_path, elf_path, tool_prefix, output_directory,
-    track_string_literals, elf_object_paths):
-  """Adds Elf section sizes and symbols."""
+def _ResolveThinArchivePaths(raw_symbols, thin_archives):
+  """Converts object_paths for thin archives to external .o paths."""
+  for symbol in raw_symbols:
+    object_path = symbol.object_path
+    if object_path.endswith(')'):
+      start_idx = object_path.rindex('(')
+      archive_path = object_path[:start_idx]
+      if archive_path in thin_archives:
+        subpath = object_path[start_idx + 1:-1]
+        symbol.object_path = ar.CreateThinObjectPath(archive_path, subpath)
+
+
+def _ParseElfInfo(map_path, elf_path, tool_prefix, track_string_literals,
+                  outdir_context=None):
+  """Adds ELF section sizes and symbols."""
   if elf_path:
     # Run nm on the elf file to retrieve the list of symbol names per-address.
     # This list is required because the .map file contains only a single name
@@ -627,15 +650,19 @@ def _ParseElfInfo(map_path, elf_path, tool_prefix, output_directory,
     # single path for these symbols.
     # Rather than record all paths for each symbol, set the paths to be the
     # common ancestor of all paths.
-    if output_directory:
-      bulk_analyzer = nm.BulkObjectFileAnalyzer(tool_prefix, output_directory)
-      bulk_analyzer.AnalyzePaths(elf_object_paths)
+    if outdir_context:
+      bulk_analyzer = nm.BulkObjectFileAnalyzer(
+          tool_prefix, outdir_context.output_directory)
+      bulk_analyzer.AnalyzePaths(outdir_context.elf_object_paths)
 
   logging.info('Parsing Linker Map')
   with _OpenMaybeGz(map_path) as map_file:
     section_sizes, raw_symbols = (
         linker_map_parser.MapFileParser().Parse(map_file))
 
+    if outdir_context and outdir_context.thin_archives:
+      _ResolveThinArchivePaths(raw_symbols, outdir_context.thin_archives)
+
   if elf_path:
     logging.debug('Validating section sizes')
     elf_section_sizes = _SectionSizesFromElf(elf_path, tool_prefix)
@@ -646,9 +673,11 @@ def _ParseElfInfo(map_path, elf_path, tool_prefix, output_directory,
         logging.error('readelf: %r', elf_section_sizes)
         sys.exit(1)
 
-  if elf_path and output_directory:
+  if elf_path and outdir_context:
     missed_object_paths = _DiscoverMissedObjectPaths(
-        raw_symbols, elf_object_paths)
+        raw_symbols, outdir_context.known_inputs)
+    missed_object_paths = ar.ExpandThinArchives(
+        missed_object_paths, outdir_context.output_directory)[0]
     bulk_analyzer.AnalyzePaths(missed_object_paths)
     bulk_analyzer.SortPaths()
     if track_string_literals:
@@ -674,11 +703,12 @@ def _ParseElfInfo(map_path, elf_path, tool_prefix, output_directory,
     names_by_address = elf_nm_result.get()
     raw_symbols = _AddNmAliases(raw_symbols, names_by_address)
 
-    if output_directory:
+    if outdir_context:
       object_paths_by_name = bulk_analyzer.GetSymbolNames()
-      logging.debug('Fetched path information for %d symbols from %d files',
-                    len(object_paths_by_name),
-                    len(elf_object_paths) + len(missed_object_paths))
+      logging.debug(
+          'Fetched path information for %d symbols from %d files',
+          len(object_paths_by_name),
+          len(outdir_context.elf_object_paths) + len(missed_object_paths))
 
       # For aliases, this provides path information where there wasn't any.
       logging.info('Creating aliases for symbols shared by multiple paths')
@@ -923,22 +953,42 @@ def CreateSectionSizesAndSymbols(
     apk_elf_result = concurrent.ForkAndCall(
         _ElfInfoFromApk, (apk_path, apk_so_path, tool_prefix))
 
+  outdir_context = None
   source_mapper = None
-  elf_object_paths = None
   if output_directory:
     # Start by finding the elf_object_paths, so that nm can run on them while
     # the linker .map is being parsed.
     logging.info('Parsing ninja files.')
-    source_mapper, elf_object_paths = ninja_parser.Parse(
-        output_directory, elf_path)
+    source_mapper, ninja_elf_object_paths = (
+        ninja_parser.Parse(output_directory, elf_path))
     logging.debug('Parsed %d .ninja files.', source_mapper.parsed_file_count)
-    assert not elf_path or elf_object_paths, (
+    assert not elf_path or ninja_elf_object_paths, (
         'Failed to find link command in ninja files for ' +
         os.path.relpath(elf_path, output_directory))
 
+    if ninja_elf_object_paths:
+      elf_object_paths, thin_archives = ar.ExpandThinArchives(
+          ninja_elf_object_paths, output_directory)
+      known_inputs = set(elf_object_paths)
+      known_inputs.update(ninja_elf_object_paths)
+    else:
+      elf_object_paths = None
+      known_inputs = None
+      # When we don't know which elf file is used, just search all paths.
+      thin_archives = set(
+          p for p in source_mapper.IterAllPaths()
+          if p.endswith('.a') and ar.IsThinArchive(
+              os.path.join(output_directory, p)))
+
+    outdir_context = _OutputDirectoryContext(
+        elf_object_paths=elf_object_paths,
+        known_inputs=known_inputs,
+        output_directory=output_directory,
+        source_mapper=source_mapper,
+        thin_archives=thin_archives)
+
   section_sizes, raw_symbols = _ParseElfInfo(
-      map_path, elf_path, tool_prefix, output_directory, track_string_literals,
-      elf_object_paths)
+      map_path, elf_path, tool_prefix, track_string_literals, outdir_context)
   elf_overhead_size = _CalculateElfOverhead(section_sizes, elf_path)
 
   pak_symbols_by_id = None
@@ -981,6 +1031,10 @@ def CreateSizeInfo(
     section_sizes, raw_symbols, metadata=None, normalize_names=True):
   """Performs operations on all symbols and creates a SizeInfo object."""
   logging.debug('Sorting %d symbols', len(raw_symbols))
+  # TODO(agrieve): Either change this sort so that it's only sorting by section
+  #     (and not using .sort()), or have it specify a total ordering (which must
+  #     also include putting padding-only symbols before others of the same
+  #     address). Note: The sort as-is takes ~1.5 seconds.
   raw_symbols.sort(key=lambda s: (
       s.IsPak(), s.IsBss(), s.section_name, s.address))
   logging.info('Processed %d symbols', len(raw_symbols))

tools/binary_size/libsupersize/ninja_parser.py

+#!/usr/bin/env python
 # 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.
 """Extract source file information from .ninja files."""
 
+from __future__ import print_function
+
+import argparse
 import logging
 import os
 import re
@@ -118,3 +122,32 @@ def Parse(output_directory, elf_path):
     to_parse.extend(sub_ninjas)
 
   return _SourceMapper(dep_map, len(seen_paths)), elf_inputs
+
+
+def main():
+  parser = argparse.ArgumentParser()
+  parser.add_argument('--output-directory', required=True)
+  parser.add_argument('--elf-path')
+  parser.add_argument('--show-inputs', action='store_true')
+  parser.add_argument('--show-mappings', action='store_true')
+  args = parser.parse_args()
+  logging.basicConfig(level=logging.DEBUG,
+                      format='%(levelname).1s %(relativeCreated)6d %(message)s')
+
+  source_mapper, elf_inputs = Parse(args.output_directory, args.elf_path)
+  if not elf_inputs:
+    elf_inputs = []
+
+  print('Found {} elf_inputs, and {} source mappings'.format(
+      len(elf_inputs), len(source_mapper._dep_map)))
+  if args.show_inputs:
+    print('elf_inputs:')
+    print('\n'.join(elf_inputs))
+  if args.show_mappings:
+    print('object_path -> source_path:')
+    for path in source_mapper.IterAllPaths():
+      print('{} -> {}'.format(path, source_mapper.FindSourceForPath(path)))
+
+
+if __name__ == '__main__':
+  main()

tools/binary_size/libsupersize/nm.py

@@ -30,7 +30,7 @@ BulkObjectFileAnalyzer:
   Alias for _BulkObjectFileAnalyzerMaster, but when SUPERSIZE_DISABLE_ASYNC=1,
   alias for _BulkObjectFileAnalyzerWorker.
   * AnalyzePaths: Run "nm" on all .o files to collect symbol names that exist
-    within each.
+    within each. Does not work with thin archives (expand them first).
   * SortPaths: Sort results of AnalyzePaths().
   * AnalyzeStringLiterals: Must be run after AnalyzePaths() has completed.
     Extracts string literals from .o files, and then locates them within the
@@ -57,6 +57,7 @@ import sys
 import threading
 import traceback
 
+import ar
 import concurrent
 import demangle
 import models
@@ -263,41 +264,6 @@ def _ReadFileChunks(path, positions):
   return ret
 
 
-def _IterArchiveChunks(path):
-  """For each .o embedded in the given .a file, yields (foo.o, foo_contents)."""
-  with open(path, 'rb') as f:
-    if f.read(8) != '!<arch>\n' :
-      raise Exception('Invalid .a: ' + path)
-    while True:
-      line = f.readline()
-      if not line:
-        return
-      parts = line.split()
-      chunk_size = int(parts[-2])
-      chunk_data = f.read(chunk_size)
-
-      name = parts[0]
-      if name == '/':
-        # Initial metadata chunk.
-        continue
-      elif name == '//':
-        name_list = chunk_data
-        continue
-      elif name[0] == '/':
-        # Name is specified as location in name table.
-        # E.g.: /123
-        name_offset = int(name[1:])
-        slash_idx = name_list.index('/', name_offset)
-        name = name_list[name_offset:slash_idx]
-      else:
-        # Name is specified inline.
-        # E.g.: foo.o/
-        # Name may not have whitespace before next field, so use rindex.
-        # E.g.: somelongername.o/1234
-        name = name[:name.rindex('/')]
-      yield name, chunk_data
-
-
 def _ParseOneObjectFileNmOutput(lines):
   # Constructors are often repeated because they have the same unmangled
   # name, but multiple mangled names. See:
@@ -332,7 +298,7 @@ def _ReadStringSections(target, output_directory, positions_by_path):
   is_archive = isinstance(target, basestring)
   string_sections_by_path = {}
   if is_archive:
-    for subpath, chunk in _IterArchiveChunks(
+    for subpath, chunk in ar.IterArchiveChunks(
         os.path.join(output_directory, target)):
       path = '{}({})'.format(target, subpath)
       positions = positions_by_path.get(path)

tools/binary_size/libsupersize/testdata/Archive.golden

@@ -24,18 +24,18 @@ Section .bss: has 40.3% of 524520 bytes accounted for from 6 symbols. 775936 byt
 * Contains 0 aliases
 * 0 symbols have shared ownership
 .data@2de7000(size_without_padding=4,padding=0,full_name=google::protobuf::internal::pLinuxKernelCmpxchg,object_path=base/base/page_allocator.o,source_path=,flags={},num_aliases=1)
-.data@2de7004(size_without_padding=4,padding=0,full_name=google::protobuf::internal::pLinuxKernelMemoryBarrier,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=,flags={},num_aliases=1)
-.data@2de7008(size_without_padding=152,padding=0,full_name=base::android::kBaseRegisteredMethods,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=,flags={rel},num_aliases=1)
-.data@2de70a0(size_without_padding=4,padding=0,full_name=base::android::g_renderer_histogram_code,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=,flags={anon},num_aliases=1)
-.data@2de70a4(size_without_padding=4,padding=0,full_name=base::android::g_library_version_number,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=,flags={anon,rel.loc},num_aliases=1)
+.data@2de7004(size_without_padding=4,padding=0,full_name=google::protobuf::internal::pLinuxKernelMemoryBarrier,object_path=third_party/WebKit.a/sub/ContiguousContainer.o,source_path=,flags={},num_aliases=1)
+.data@2de7008(size_without_padding=152,padding=0,full_name=base::android::kBaseRegisteredMethods,object_path=third_party/WebKit.a/sub/ContiguousContainer.o,source_path=,flags={rel},num_aliases=1)
+.data@2de70a0(size_without_padding=4,padding=0,full_name=base::android::g_renderer_histogram_code,object_path=third_party/WebKit.a/sub/ContiguousContainer.o,source_path=,flags={anon},num_aliases=1)
+.data@2de70a4(size_without_padding=4,padding=0,full_name=base::android::g_library_version_number,object_path=third_party/WebKit.a/sub/ContiguousContainer.o,source_path=,flags={anon,rel.loc},num_aliases=1)
 .data@2dffd88(size_without_padding=0,padding=101600,full_name=** symbol gap 0 (end of section),object_path=,source_path=,flags={},num_aliases=1)
-.data.rel.ro@2cd8500(size_without_padding=56,padding=0,full_name=ChromeMainDelegateAndroid [vtable],object_path=third_party/WebKit.a/PaintChunker.o,source_path=,flags={},num_aliases=1)
+.data.rel.ro@2cd8500(size_without_padding=56,padding=0,full_name=ChromeMainDelegateAndroid [vtable],object_path=third_party/WebKit.a/sub/PaintChunker.o,source_path=,flags={},num_aliases=1)
 .data.rel.ro@2cd8538(size_without_padding=24,padding=0,full_name=mojo::MessageReceiver [vtable],object_path=base/base/page_allocator.o,source_path=,flags={},num_aliases=1)
 .data.rel.ro@2cd8550(size_without_padding=12,padding=0,full_name=kMethodsAnimationFrameTimeHistogram,object_path=base/base/page_allocator.o,source_path=,flags={},num_aliases=1)
 .data.rel.ro@2ddc608(size_without_padding=0,padding=1065132,full_name=** symbol gap 0 (end of section),object_path=,source_path=,flags={},num_aliases=1)
 .data.rel.ro.local@2c176f0(size_without_padding=56,padding=0,full_name=ChromeMainDelegate [vtable],object_path=third_party/icu/icuuc/ucnv_ext.o,source_path=,flags={},num_aliases=1)
 .data.rel.ro.local@2c17728(size_without_padding=24,padding=0,full_name=chrome::mojom::FieldTrialRecorder [vtable],object_path=third_party/icu/icuuc/ucnv_ext.o,source_path=,flags={},num_aliases=1)
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+.data.rel.ro.local@2c17740(size_without_padding=789904,padding=0,full_name=chrome::mojom::FieldTrialRecorderProxy [vtable],object_path=third_party/WebKit.a/sub/ContiguousContainer.o,source_path=,flags={},num_aliases=1)
 .data.rel.ro.local@2cd84e0(size_without_padding=16,padding=16,full_name=.Lswitch.table.45,object_path=third_party/gvr-android-sdk/libgvr_shim_static_arm.a/libcontroller_api_impl.a_controller_api_impl.o,source_path=,flags={},num_aliases=1)
 .data.rel.ro.local@2cd84f0(size_without_padding=8,padding=0,full_name=kSystemClassPrefixes,object_path=third_party/gvr-android-sdk/libgvr_shim_static_arm.a/libport_android_jni.a_jni_utils.o,source_path=,flags={anon},num_aliases=1)
 .rodata@266e600(size_without_padding=32,padding=0,full_name=** merge strings,object_path=,source_path=,flags={},num_aliases=1)
@@ -44,9 +44,9 @@ Section .bss: has 40.3% of 524520 bytes accounted for from 6 symbols. 775936 byt
 .rodata@284e364(size_without_padding=0,padding=3,full_name=** symbol gap 0,object_path=,source_path=,flags={},num_aliases=1)
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-.rodata@284e398(size_without_padding=32,padding=0,full_name=chrome::mojom::FilePatcher::Name_,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=,flags={},num_aliases=1)
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 .rodata@2c158e4(size_without_padding=0,padding=3286112,full_name=** symbol gap 1 (end of section),object_path=,source_path=,flags={},num_aliases=1)
 .text@28d900(size_without_padding=16,padding=0,full_name=_GLOBAL__sub_I_page_allocator.cc,object_path=base/base/page_allocator.o,source_path=,flags={startup},num_aliases=1)
 .text@28d910(size_without_padding=56,padding=0,full_name=_GLOBAL__sub_I_bbr_sender.cc,object_path=base/base/page_allocator.o,source_path=,flags={startup},num_aliases=1)
@@ -57,11 +57,11 @@ Section .bss: has 40.3% of 524520 bytes accounted for from 6 symbols. 775936 byt
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 .text@28f1e0(size_without_padding=69120,padding=4,full_name=foo_bar,object_path=third_party/icu/icuuc/ucnv_ext.o,source_path=,flags={unlikely},num_aliases=1)
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tools/binary_size/libsupersize/testdata/Archive_Elf.golden

@@ -36,18 +36,18 @@ Section .other: has 100.0% of 33984171 bytes accounted for from 1 symbols. 0 byt
 * Contains 0 aliases
 * 0 symbols have shared ownership
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+.data.rel.ro@2cd8500(size_without_padding=56,padding=0,full_name=ChromeMainDelegateAndroid [vtable],object_path=third_party/sub/PaintChunker.o,source_path=third_party/paint.cc,flags={},num_aliases=1)
 .data.rel.ro@2cd8538(size_without_padding=24,padding=0,full_name=mojo::MessageReceiver [vtable],object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={},num_aliases=1)
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+.data.rel.ro.local@2c17740(size_without_padding=789904,padding=0,full_name=chrome::mojom::FieldTrialRecorderProxy [vtable],object_path=third_party/sub/ContiguousContainer.o,source_path=third_party/container.c,flags={},num_aliases=1)
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@@ -59,9 +59,9 @@ Section .other: has 100.0% of 33984171 bytes accounted for from 1 symbols. 0 byt
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@@ -76,11 +76,11 @@ Section .other: has 100.0% of 33984171 bytes accounted for from 1 symbols. 0 byt
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tools/binary_size/libsupersize/testdata/Archive_Pak_Files.golden

@@ -40,18 +40,18 @@ Section .other: has 100.0% of 33984171 bytes accounted for from 1 symbols. 0 byt
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 .data.rel.ro.local@2c17728(size_without_padding=24,padding=0,full_name=chrome::mojom::FieldTrialRecorder [vtable],object_path=third_party/icu/icuuc/ucnv_ext.o,source_path=third_party/icu/ucnv_ext.c,flags={gen},num_aliases=1)
-.data.rel.ro.local@2c17740(size_without_padding=789904,padding=0,full_name=chrome::mojom::FieldTrialRecorderProxy [vtable],object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={},num_aliases=1)
+.data.rel.ro.local@2c17740(size_without_padding=789904,padding=0,full_name=chrome::mojom::FieldTrialRecorderProxy [vtable],object_path=third_party/sub/ContiguousContainer.o,source_path=third_party/container.c,flags={},num_aliases=1)
 .data.rel.ro.local@2cd84e0(size_without_padding=16,padding=16,full_name=.Lswitch.table.45,object_path=third_party/gvr-android-sdk/libgvr_shim_static_arm.a/libcontroller_api_impl.a_controller_api_impl.o,source_path=,flags={},num_aliases=1)
 .data.rel.ro.local@2cd84f0(size_without_padding=8,padding=0,full_name=kSystemClassPrefixes,object_path=third_party/gvr-android-sdk/libgvr_shim_static_arm.a/libport_android_jni.a_jni_utils.o,source_path=,flags={anon},num_aliases=1)
 .other@0(size_without_padding=0,padding=33984171,full_name=Overhead: ELF file,object_path=,source_path=,flags={},num_aliases=1)
@@ -63,9 +63,9 @@ Section .other: has 100.0% of 33984171 bytes accounted for from 1 symbols. 0 byt
 .rodata@284e364(size_without_padding=0,padding=3,full_name=** symbol gap 0,object_path=,source_path=,flags={},num_aliases=1)
 .rodata@284e364(size_without_padding=8,padding=0,full_name=,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={},num_aliases=1)
 .rodata@284e370(size_without_padding=40,padding=4,full_name=Name,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={},num_aliases=1)
-.rodata@284e398(size_without_padding=32,padding=0,full_name=chrome::mojom::FilePatcher::Name_,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={},num_aliases=1)
-.rodata@28f3450(size_without_padding=48,padding=675992,full_name=kAnimationFrameTimeHistogramClassPath,object_path=third_party/WebKit.a/PaintChunker.o,source_path=third_party/paint.cc,flags={anon},num_aliases=1)
-.rodata@28f3480(size_without_padding=4,padding=0,full_name=blink::CSSValueKeywordsHash::findValueImpl(char const*, unsigned int)::value_word_list,object_path=third_party/WebKit.a/PaintChunker.o,source_path=third_party/paint.cc,flags={anon},num_aliases=1)
+.rodata@284e398(size_without_padding=32,padding=0,full_name=chrome::mojom::FilePatcher::Name_,object_path=third_party/sub/ContiguousContainer.o,source_path=third_party/container.c,flags={},num_aliases=1)
+.rodata@28f3450(size_without_padding=48,padding=675992,full_name=kAnimationFrameTimeHistogramClassPath,object_path=third_party/sub/PaintChunker.o,source_path=third_party/paint.cc,flags={anon},num_aliases=1)
+.rodata@28f3480(size_without_padding=4,padding=0,full_name=blink::CSSValueKeywordsHash::findValueImpl(char const*, unsigned int)::value_word_list,object_path=third_party/sub/PaintChunker.o,source_path=third_party/paint.cc,flags={anon},num_aliases=1)
 .rodata@2c158e4(size_without_padding=0,padding=3286112,full_name=** symbol gap 1 (end of section),object_path=,source_path=,flags={},num_aliases=1)
 .text@28d900(size_without_padding=16,padding=0,full_name=_GLOBAL__sub_I_page_allocator.cc,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={startup},num_aliases=1)
 .text@28d910(size_without_padding=56,padding=0,full_name=_GLOBAL__sub_I_bbr_sender.cc,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={startup},num_aliases=1)
@@ -80,11 +80,11 @@ Section .other: has 100.0% of 33984171 bytes accounted for from 1 symbols. 0 byt
 .text@2a0000(size_without_padding=16,padding=32,full_name=blink::ContiguousContainerBase::shrinkToFit(),object_path=,source_path=,flags={},num_aliases=2)
 .text@2a0010(size_without_padding=12,padding=0,full_name=BarAlias(),object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_float.o,source_path=third_party/fft_float.cc,flags={},num_aliases=4)
 .text@2a0010(size_without_padding=12,padding=0,full_name=FooAlias(),object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_float.o,source_path=third_party/fft_float.cc,flags={},num_aliases=4)
-.text@2a0010(size_without_padding=12,padding=0,full_name=blink::ContiguousContainerBase::shrinkToFit(),object_path=third_party/WebKit.a/PaintChunker.o,source_path=third_party/paint.cc,flags={clone},num_aliases=4)
 .text@2a0010(size_without_padding=12,padding=0,full_name=blink::ContiguousContainerBase::shrinkToFit(),object_path=third_party/icu/icuuc/ucnv_ext.o,source_path=third_party/icu/ucnv_ext.c,flags={gen,clone},num_aliases=4)
-.text@2a0020(size_without_padding=24,padding=4,full_name=blink::ContiguousContainerBase::ContiguousContainerBase(blink::ContiguousContainerBase&&),object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={},num_aliases=1)
+.text@2a0010(size_without_padding=12,padding=0,full_name=blink::ContiguousContainerBase::shrinkToFit(),object_path=third_party/sub/PaintChunker.o,source_path=third_party/paint.cc,flags={clone},num_aliases=4)
+.text@2a0020(size_without_padding=24,padding=4,full_name=blink::ContiguousContainerBase::ContiguousContainerBase(blink::ContiguousContainerBase&&),object_path=third_party/sub/ContiguousContainer.o,source_path=third_party/container.c,flags={},num_aliases=1)
 .text@2a1000(size_without_padding=0,padding=4040,full_name=** symbol gap 1,object_path=,source_path=,flags={},num_aliases=1)
-.text@2a1000(size_without_padding=94,padding=0,full_name=blink::PaintChunker::releasePaintChunks(),object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={anon,clone},num_aliases=1)
+.text@2a1000(size_without_padding=94,padding=0,full_name=blink::PaintChunker::releasePaintChunks(),object_path=third_party/sub/ContiguousContainer.o,source_path=third_party/container.c,flags={anon,clone},num_aliases=1)
 .text@24ca628(size_without_padding=0,padding=35821002,full_name=** symbol gap 2 (end of section),object_path=,source_path=,flags={},num_aliases=1)
 .bss@0(size_without_padding=262144,padding=0,full_name=ff_cos_131072,object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_float.o,source_path=third_party/fft_float.cc,flags={},num_aliases=1)
 .bss@0(size_without_padding=131072,padding=0,full_name=ff_cos_131072_fixed,object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_fixed.o,source_path=third_party/fft_fixed.cc,flags={},num_aliases=1)

tools/binary_size/libsupersize/testdata/Console.golden

@@ -170,9 +170,9 @@ Index | Running Total | Section@Address | PSS | Path
              BarAlias (num_aliases=4)
 39)  77769423 (100.0%) t@0x2a0010   3 (size=12)    third_party/fft_float.cc
              FooAlias (num_aliases=4)
-40)  77769426 (100.0%) t@0x2a0010   3 (size=12)    third_party/paint.cc
+40)  77769426 (100.0%) t@0x2a0010   3 (size=12)    $root_gen_dir/third_party/icu/ucnv_ext.c
              blink::ContiguousContainerBase::shrinkToFit (num_aliases=4)
-41)  77769429 (100.0%) t@0x2a0010   3 (size=12)    $root_gen_dir/third_party/icu/ucnv_ext.c
+41)  77769429 (100.0%) t@0x2a0010   3 (size=12)    third_party/paint.cc
              blink::ContiguousContainerBase::shrinkToFit (num_aliases=4)
 42)  77769457 (100.0%) t@0x2a0020   28             third_party/container.c
              blink::ContiguousContainerBase::ContiguousContainerBase

tools/binary_size/libsupersize/testdata/Diff_Basic.golden

@@ -55,5 +55,5 @@ Section Legend: t=.text, r=.rodata, R=.data.rel.ro, d=.data, b=.bss
 Index | Running Total | Section@Address | ...
 ------------------------------------------------------------
 ~ 0)         10 (100.0%) d@0x2de70a0  +10 (-6->4)  num_aliases=1
-               source_path=third_party/container.c 	object_path=third_party/WebKit.a/ContiguousContainer.o
+               source_path=third_party/container.c 	object_path=third_party/sub/ContiguousContainer.o
                flags={}  name=base::android::g_renderer_histogram_code

tools/binary_size/libsupersize/testdata/mock_output_directory/obj/third_party/WebKit.a

+!<thin>
+/               0           0     0     0       60        `
+For convenience, each line of this string table is 60 bytes
+//              0           0     0     0       120       `
+                                        sub/PaintChunker.o/
+                                 sub/ContiguousContainer.o/
+/40             0           0     0     644     281516    `
+/93             0           0     0     644     281516    `

tools/binary_size/libsupersize/testdata/mock_output_directory/obj/third_party/ffmpeg/libffmpeg_internal.a

+This file has to exist so that it can be checked for whether or not it is a
+thin archive. Thin archives start with "!<thin>\n". As you can see, this file is
+not a thin archive.

tools/binary_size/libsupersize/testdata/mock_toolchain/mock_nm.py

@@ -38,16 +38,14 @@ _OBJECT_OUTPUTS = {
          ' int, unsigned short const*, int, unsigned int*, signed char, signed '
          'char)'),
     ],
-    'obj/third_party/WebKit.a': [
-        '',
-        'PaintChunker.o:',
+    'obj/third_party/sub/PaintChunker.o': [
         '01010101 t ' + _SHRINK_TO_FIT,
         '010101 t (anonymous namespace)::kAnimationFrameTimeHistogramClassPath',
         '010101 r vtable for ChromeMainDelegateAndroid',
         ('01010101 r blink::(anonymous namespace)::CSSValueKeywordsHash::findVa'
          'lueImpl(char const*, unsigned int)::value_word_list'),
-        '',
-        'ContiguousContainer.o:',
+    ],
+    'obj/third_party/sub/ContiguousContainer.o': [
         '01010101 d chrome::mojom::FilePatcher::Name_',
         '01010101 r vtable for chrome::mojom::FieldTrialRecorderProxy',
         '01010101 r google::protobuf::internal::pLinuxKernelMemoryBarrier',

tools/binary_size/libsupersize/testdata/test.map

@@ -90,17 +90,17 @@ Memory map
  .text.unlikely.foo_bar
                 0x0028f1e0       0x10e00 ./obj/third_party/icu/../icu/icuuc/ucnv_ext.o
  .text._ZN5blink23ContiguousContainerBase11shrinkToFitEv
-                0x002a0000       0x10 obj/third_party/WebKit.a(PaintChunker.o)
+                0x002a0000       0x10 obj/third_party/WebKit.a(sub/PaintChunker.o)
                 0x002a0001                blink::ContiguousContainerBase::shrinkToFit()
  .text.hot._ZN5blink23ContiguousContainerBase11shrinkToFitEv2.part.1234.isra.2
-                0x002a0010       0xc obj/third_party/WebKit.a(PaintChunker.o)
+                0x002a0010       0xc obj/third_party/WebKit.a(sub/PaintChunker.o)
                 0x002a0011                blink::ContiguousContainerBase::shrinkToFit()
  .text._ZN5blink23ContiguousContainerBaseC2EOS0_
-                0xffffffffffffffff       0x18 obj/third_party/WebKit.a(ContiguousContainer.o)
+                0xffffffffffffffff       0x18 obj/third_party/WebKit.a(sub/ContiguousContainer.o)
                 0x002a0021                blink::ContiguousContainerBase::ContiguousContainerBase(blink::ContiguousContainerBase&&)
                 0x002a0021                blink::ContiguousContainerBase::ContiguousContainerBase(blink::ContiguousContainerBase&&)
  .text._ZN10_GLOBAL__N5blink12PaintChunker18releasePaintChunksEv.part.1
-                0x002a1000       0x5e obj/third_party/WebKit.a(ContiguousContainer.o)
+                0x002a1000       0x5e obj/third_party/WebKit.a(sub/ContiguousContainer.o)
                 0x002a1001                (anonymous namespace)::blink::PaintChunker::releasePaintChunks() [clone .part.1]
 
 .ARM.exidx      0x024ca628   0x1771c8
@@ -123,12 +123,12 @@ Memory map
                 0x0284e370       0x28 obj/base/base/page_allocator.o
                 0x0284e370                Name
  .rodata._ZN6chrome5mojom11FilePatcher5Name_E
-                0x0284e398       0x20 obj/third_party/WebKit.a(ContiguousContainer.o)
+                0x0284e398       0x20 obj/third_party/WebKit.a(sub/ContiguousContainer.o)
                 0x0284e398                chrome::mojom::FilePatcher::Name_
  .rodata._ZN12_GLOBAL__N_1L37kAnimationFrameTimeHistogramClassPathE
-                0x028f3450       0x30 obj/third_party/WebKit.a(PaintChunker.o)
+                0x028f3450       0x30 obj/third_party/WebKit.a(sub/PaintChunker.o)
  .rodata._ZZN10_GLOBAL__N5blink20CSSValueKeywordsHash13findValueImplEPKcjE15value_word_list
-                0x028f3480       0x4 obj/third_party/WebKit.a(PaintChunker.o)
+                0x028f3480       0x4 obj/third_party/WebKit.a(sub/PaintChunker.o)
                 0x028f3480                blink::(anonymous namespace)::CSSValueKeywordsHash::findValueImpl(char const*, unsigned int)::value_word_list
 
 .data.rel.ro.local
@@ -140,7 +140,7 @@ Memory map
                 0x02c17728       0x18 ./obj/third_party/icu/../icu/icuuc/ucnv_ext.o
                 0x02c17728                vtable for chrome::mojom::FieldTrialRecorder
  .data.rel.ro.local._ZTVN6chrome5mojom23FieldTrialRecorderProxyE
-                0x02c17740       0xc0d90 obj/third_party/WebKit.a(ContiguousContainer.o)
+                0x02c17740       0xc0d90 obj/third_party/WebKit.a(sub/ContiguousContainer.o)
                 0x02c17740                vtable for chrome::mojom::FieldTrialRecorderProxy
  .data.rel.ro.local..Lswitch.table.45
                 0x02cd84e0       0x10 ../../third_party/gvr-android-sdk/libgvr_shim_static_arm.a(libcontroller_api_impl.a_controller_api_impl.o)
@@ -149,7 +149,7 @@ Memory map
 
 .data.rel.ro    0x02cd8500   0x104108
  .data.rel.ro._ZTV25ChromeMainDelegateAndroid
-                0x02cd8500       0x38 obj/third_party/WebKit.a(PaintChunker.o)
+                0x02cd8500       0x38 obj/third_party/WebKit.a(sub/PaintChunker.o)
                 0x02cd8500                vtable for ChromeMainDelegateAndroid
  .data.rel.ro._ZTVN4mojo15MessageReceiverE
                 0x02cd8538       0x18 obj/base/base/page_allocator.o
@@ -179,14 +179,14 @@ Memory map
                 0x02de7000        0x4 obj/base/base/page_allocator.o
                 0x02de7000                google::protobuf::internal::pLinuxKernelCmpxchg
  .data._ZN6google8protobuf8internal25pLinuxKernelMemoryBarrierE
-                0x02de7004        0x4 obj/third_party/WebKit.a(ContiguousContainer.o)
+                0x02de7004        0x4 obj/third_party/WebKit.a(sub/ContiguousContainer.o)
                 0x02de7004                google::protobuf::internal::pLinuxKernelMemoryBarrier
  .data.rel._ZN4base7androidL22kBaseRegisteredMethodsE
-                0x02de7008       0x98 obj/third_party/WebKit.a(ContiguousContainer.o)
+                0x02de7008       0x98 obj/third_party/WebKit.a(sub/ContiguousContainer.o)
  .data._ZN4base7android12_GLOBAL__N_125g_renderer_histogram_codeE
-                0x02de70a0        0x4 obj/third_party/WebKit.a(ContiguousContainer.o)
+                0x02de70a0        0x4 obj/third_party/WebKit.a(sub/ContiguousContainer.o)
  .data.rel.local._ZN4base7android12_GLOBAL__N_124g_library_version_numberE
-                0x02de70a4        0x4 obj/third_party/WebKit.a(ContiguousContainer.o)
+                0x02de70a4        0x4 obj/third_party/WebKit.a(sub/ContiguousContainer.o)
 
 .bss            0x02dffda0   0x13d7e8
  .bss.g_chrome_content_browser_client

tools/binary_size/libsupersize/third_party/gvr-android-sdk/libgvr_shim_static_arm.a

+This file has to exist so that it can be checked for whether or not it is a
+thin archive. Thin archives start with "!<thin>\n". As you can see, this file is
+not a thin archive.