Use whitelist to check static initializers

This CL does two things:
1. Replace the SI count check with a whitelist check.
2. Add InstrProfilingRuntime.cc to the whitelist because coverage build
   needs it and it is ONLY used on coverage build.

This change only applies to Linux platform, and in order to make Mac
platform work, a separate CL is required to change
//tools/mac/dump-static-initializers.py to have the same output format
as //tools/linux/dump-static-initializers.py.

Bug: 956591
Change-Id: I54119676bea59a8f1e6fdba470bbeac32b121c3c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1653319Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#668535}

testing/scripts/check_static_initializers.py

@@ -11,14 +11,25 @@ import sys
 
 import common
 
-# If something adds a static initializer, revert it, don't increase these
-# numbers. We don't accept regressions in static initializers.
-EXPECTED_LINUX_SI_COUNTS = {
-    'chrome': 4,
-    'nacl_helper': 4,
-    'nacl_helper_bootstrap': 0,
+# A list of whitelisted files that are allowed to have static initializers.
+# If something adds a static initializer, revert it. We don't accept regressions
+# in static initializers.
+_LINUX_SI_FILE_WHITELIST = {
+    'chrome': [
+        'InstrProfilingRuntime.cc',  # Only in coverage builds, not production.
+        'atomicops_internals_x86.cc',  # TODO(crbug.com/973551): Remove.
+        'debugallocation_shim.cc',  # TODO(crbug.com/973552): Remove.
+        'iostream.cpp',  # TODO(crbug.com/973554): Remove.
+        'spinlock.cc',  # TODO(crbug.com/973556): Remove.
+    ],
+    'nacl_helper_bootstrap': [],
 }
+_LINUX_SI_FILE_WHITELIST['nacl_helper'] = _LINUX_SI_FILE_WHITELIST['chrome']
 
+# TODO: Convert Mac to use the whitelist, but need to first modify
+# //tools/mac/dump-static-initializers.py to have the same stdout format as
+# //tools/linux/dump-static-initializers.py.
+#
 # A static initializer is needed on Mac for libc++ to set up std::cin/cout/cerr
 # before main() runs.
 EXPECTED_MAC_SI_COUNT = 1
@@ -92,56 +103,39 @@ def main_mac(src_dir):
 
 
 def main_linux(src_dir):
-
-  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.*$' % re.escape(section_name), readelf_stdout,
-                      re.MULTILINE)
-    if not match:
-      return (False, -1)
-    size_str = re.split(r'\W+', match.group(0))[5]
-    return (True, int(size_str, 16))
-
-  def get_word_size(binary_name):
-    stdout = run_process(['readelf', '-h', binary_name])
-    elf_class_line = re.search('Class:.*$', stdout, re.MULTILINE).group(0)
-    elf_class = re.split(r'\W+', elf_class_line)[1]
-    if elf_class == 'ELF32':
-      return 4
-    elif elf_class == 'ELF64':
-      return 8
-    raise Exception('Unsupported architecture')
-
   ret = 0
-  for binary_name in EXPECTED_LINUX_SI_COUNTS:
+  for binary_name in _LINUX_SI_FILE_WHITELIST:
     if not os.path.exists(binary_name):
       continue
-    # NOTE: this is very implementation-specific and makes assumptions
-    # about how compiler and linker implement global static initializers.
-    si_count = 0
-    stdout = run_process(['readelf', '-SW', binary_name])
-    has_init_array, init_array_size = get_elf_section_size(stdout, 'init_array')
-    if has_init_array:
-      si_count = init_array_size / get_word_size(binary_name)
-      # In newer versions of gcc crtbegin.o inserts frame_dummy into .init_array
-      # but we don't want to count this entry, since its always present and not
-      # related to our code.
-      stdout = run_process(['objdump', '-t', binary_name, '-j' '.init_array'])
-      if '__frame_dummy_init_array_entry' in stdout:
-        si_count -= 1
-
-    # Print the list of static initializers.
-    if (binary_name in EXPECTED_LINUX_SI_COUNTS and
-        si_count > EXPECTED_LINUX_SI_COUNTS[binary_name]):
-      print('Expected <= %d static initializers in %s, but found %d' %
-            (EXPECTED_LINUX_SI_COUNTS[binary_name], binary_name, si_count))
-      ret = 1
-    if si_count > 0:
-      dump_static_initializers = os.path.join(src_dir, 'tools', 'linux',
-                                              'dump-static-initializers.py')
-      stdout = run_process([dump_static_initializers, '-d', binary_name])
-      print '\n# Static initializers in %s:' % binary_name
-      print stdout
+
+    dump_static_initializers = os.path.join(src_dir, 'tools', 'linux',
+                                            'dump-static-initializers.py')
+    stdout = run_process([dump_static_initializers, '-d', binary_name])
+    # The output has the following format:
+    # First lines: '# <file_name> <si_name>'
+    # Last line: '# Found <num> static initializers in <num> files.'
+    #
+    # For example:
+    # # spinlock.cc GetSystemCPUsCount()
+    # # spinlock.cc adaptive_spin_count
+    # # Found 2 static initializers in 1 files.
+
+    files_with_si = set()
+    for line in stdout.splitlines()[:-1]:
+      parts = line.split(' ', 2)
+      assert len(parts) == 3 and parts[0] == '#'
+
+      files_with_si.add(parts[1])
+
+    for f in files_with_si:
+      if f not in _LINUX_SI_FILE_WHITELIST[binary_name]:
+        ret = 1
+        print('Error: file "%s" is not expected to have static initializers in'
+              ' binary "%s"') % (f, binary_name)
+
+    print '\n# Static initializers in %s:' % binary_name
+    print stdout
+
   return ret