[Android] Change resource_sizes.py to get static initializers the same as size.py

build/android/resource_sizes.py

Index: build/android/resource_sizes.py
diff --git a/build/android/resource_sizes.py b/build/android/resource_sizes.py
index 00df8efc3de696b8db0ba0bcf14c01d48dca2f0b..0ee5366c195d15b5f3e197fa19e37de868a19ea4 100755
--- a/build/android/resource_sizes.py
+++ b/build/android/resource_sizes.py
@@ -37,24 +37,6 @@ with host_paths.SysPath(host_paths.BUILD_COMMON_PATH):
 # using 'nm' on libchrome.so which results from a GCC official build (i.e.
 # Clang is not supported currently).
 
-STATIC_INITIALIZER_SYMBOL_PREFIX = '_GLOBAL__I_'
-
-EXPECTED_STATIC_INITIALIZERS = frozenset([
-    'allocators.cpp',
-    'common.pb.cc',
-    'defaults.cc',
-    'generated_message_util.cc',
-    'locale_impl.cpp',
-    'timeutils.cc',
-    'watchdog.cc',
-    # http://b/6354040
-    'SkFontHost_android.cpp',
-    # http://b/6354040
-    'isolate.cc',
-    'assembler_arm.cc',
-    'isolate.cc',
-])
-
 _BASE_CHART = {
     'format_version': '0.1',
     'benchmark_name': 'resource_sizes',
@@ -66,19 +48,43 @@ _BASE_CHART = {
 _RC_HEADER_RE = re.compile(r'^#define (?P<name>\w+) (?P<id>\d+)$')
 
 
+def CountStaticInitializers(so_path):
+  def get_elf_section_size(readelf_stdout, section_name):
+    # Matches: .ctors PROGBITS 000000000516add0 5169dd0 000010 00 WA 0 0 8
+    match = re.search(r'\.%s.*$' % re.escape(section_name),
+                      readelf_stdout, re.MULTILINE)
+    if not match:
+      return (False, -1)
+    size_str = re.split(r'\W+', match.group(0))[5]
+    return (True, int(size_str, 16))
+
+  # Find the number of files with at least one static initializer.
+  # First determine if we're 32 or 64 bit
+  stdout = cmd_helper.GetCmdOutput(['readelf', '-h', so_path])
+  elf_class_line = re.search('Class:.*$', stdout, re.MULTILINE).group(0)
+  elf_class = re.split(r'\W+', elf_class_line)[1]
+  if elf_class == 'ELF32':
+    word_size = 4
+  else:
+    word_size = 8
+
+  # Then find the number of files with global static initializers.
+  # NOTE: this is very implementation-specific and makes assumptions
+  # about how compiler and linker implement global static initializers.
+  si_count = 0
+  stdout = cmd_helper.GetCmdOutput(['readelf', '-SW', so_path])
+  has_init_array, init_array_size = get_elf_section_size(stdout, 'init_array')
+  if has_init_array:
+    si_count = init_array_size / word_size
+  si_count = max(si_count, 0)
+  return si_count
+
+
 def GetStaticInitializers(so_path):
-  """Returns a list of static initializers found in the non-stripped library
-     located at the provided path. Note that this function assumes that the
-     library was compiled with GCC.
-  """
-  output = cmd_helper.GetCmdOutput(['nm', so_path])
-  static_initializers = []
-  for line in output:
-    symbol_name = line.split(' ').pop().rstrip()
-    if STATIC_INITIALIZER_SYMBOL_PREFIX in symbol_name:
-      static_initializers.append(
-          symbol_name.replace(STATIC_INITIALIZER_SYMBOL_PREFIX, ''))
-  return static_initializers
+  dump_initializers = os.path.join(host_paths.DIR_SOURCE_ROOT, 'tools', 'linux',

[perezju, 2016/02/01 10:23:59]

nit: maybe this can be a module-level constant?

[rnephew (Reviews Here), 2016/02/01 15:46:19]

Done.

+                                   'dump-static-initializers.py')
+  output = cmd_helper.GetCmdOutput([dump_initializers, '-d', so_path])
+  return output.splitlines()
 
 
 def ReportPerfResult(chart_data, graph_title, trace_title, value, units,
@@ -308,12 +314,12 @@ def PrintStaticInitializersCount(so_with_symbols_path, chartjson=None):
        so_with_symbols_path: Path to the unstripped libchrome.so file.
   """
   print 'Files with static initializers:'
+  si_count = CountStaticInitializers(so_with_symbols_path)
   static_initializers = GetStaticInitializers(so_with_symbols_path)

[perezju, 2016/02/01 10:23:59]

Asking mostly out of ignorance, but could si_count != len(static_initializers)?

Also, why do we GetStaticInitializers? It seems that we only print them to
stdout, but do nothing else with them.

[rnephew (Reviews Here), 2016/02/01 15:46:19]

https://codereview.chromium.org/1445633002/

[perezju, 2016/02/03 11:09:02]

I had a look but I'm still confused:

1. is si_count == len(static_initializers) always true? if not, why not?

2. why do we need to compute the list of static_initializers if they are not
reported as perf results?

   print '\n'.join(static_initializers)
 
   ReportPerfResult(chartjson, 'StaticInitializersCount', 'count',
-                   len(static_initializers), 'count')
-
+                   si_count, 'count')
 
 def _FormatBytes(byts):
   """Pretty-print a number of bytes."""