Add gn args to metadata and metadata diffing

tools/binary_size/models.py

 # 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.
 """Classes that comprise the data model for binary size analysis.
 
 The primary classes are Symbol, and SymbolGroup.
 
 Some notes on common propertis:
   * address: The start address of the symbol.
         May be 0 (e.g. for .bss or for SymbolGroups).
@@ skipping 15 matching lines @@
 
 import collections
 import copy
 import os
 import re
 
 import match_util
 
 
 METADATA_GIT_REVISION = 'git_revision'
-METADATA_MAP_FILENAME = 'map_file_name'
-METADATA_ELF_FILENAME = 'elf_file_name'
+METADATA_MAP_FILENAME = 'map_file_name'  # Path relative to output_directory.
+METADATA_ELF_FILENAME = 'elf_file_name'  # Path relative to output_directory.
 METADATA_ELF_MTIME = 'elf_mtime'  # int timestamp in utc.
 METADATA_ELF_BUILD_ID = 'elf_build_id'
+METADATA_GN_ARGS = 'gn_args'
+
 
 SECTION_TO_SECTION_NAME = {
     'b': '.bss',
     'd': '.data',
     'r': '.rodata',
     't': '.text',
 }
 
 
 class SizeInfo(object):
   """Represents all size information for a single binary.
 
   Fields:
     section_sizes: A dict of section_name -> size.
-    symbols: A SymbolGroup (or SymbolDiff) with all symbols in it.
+    symbols: A SymbolGroup with all symbols in it.
     metadata: A dict.
   """
   __slots__ = (
       'section_sizes',
       'symbols',
       'metadata',
   )
 
   """Root size information."""
   def __init__(self, section_sizes, symbols, metadata=None):
     self.section_sizes = section_sizes  # E.g. {'.text': 0}
     self.symbols = symbols  # List of symbols sorted by address per-section.
     self.metadata = metadata or {}
 
 
+class SizeInfoDiff(object):
+  """What you get when you Diff() two SizeInfo objects.
+
+  Fields:
+    section_sizes: A dict of section_name -> size delta.
+    symbols: A SymbolDiff with all symbols in it.
+    old_metadata: metadata of the "old" SizeInfo.
+    new_metadata: metadata of the "new" SizeInfo.
+  """
+  __slots__ = (
+      'section_sizes',
+      'symbols',
+      'old_metadata',
+      'new_metadata',
+  )
+
+  def __init__(self, section_sizes, symbols, old_metadata, new_metadata):
+    self.section_sizes = section_sizes
+    self.symbols = symbols
+    self.old_metadata = old_metadata
+    self.new_metadata = new_metadata
+
+
 class BaseSymbol(object):
   """Base class for Symbol and SymbolGroup.
 
   Refer to module docs for field descriptions.
   """
   __slots__ = ()
 
   @property
   def section(self):
     """Returns the one-letter section.
@@ skipping 462 matching lines @@
   def IsRemoved(self, sym):
     return id(sym) in self._removed_ids
 
   def WhereNotUnchanged(self):
     return self.Filter(lambda s: not self.IsSimilar(s) or s.size)
 
 
 def Diff(new, old):
   """Diffs two SizeInfo or SymbolGroup objects.
 
-  When diffing SizeInfos, ret.section_sizes are the result of |new| - |old|, and
-  ret.symbols will be a SymbolDiff.
-
+  When diffing SizeInfos, a SizeInfoDiff is returned.
   When diffing SymbolGroups, a SymbolDiff is returned.
 
   Returns:
     Returns a SizeInfo when args are of type SizeInfo.
     Returns a SymbolDiff when args are of type SymbolGroup.
   """
   if isinstance(new, SizeInfo):
     assert isinstance(old, SizeInfo)
     section_sizes = {
         k:new.section_sizes[k] - v for k, v in old.section_sizes.iteritems()}
     symbol_diff = Diff(new.symbols, old.symbols)
-    return SizeInfo(section_sizes, symbol_diff)
+    return SizeInfoDiff(section_sizes, symbol_diff, old.metadata, new.metadata)
 
   assert isinstance(new, SymbolGroup) and isinstance(old, SymbolGroup)
   symbols_by_key = collections.defaultdict(list)
   for s in old:
     symbols_by_key[s._Key()].append(s)
 
   added = []
   removed = []
   similar = []
   # For similar symbols, padding is zeroed out. In order to not lose the
@@ skipping 33 matching lines @@
 
 def _ExtractPrefixBeforeSeparator(string, separator, count=1):
   idx = -len(separator)
   prev_idx = None
   for _ in xrange(count):
     idx = string.find(separator, idx + len(separator))
     if idx < 0:
       break
     prev_idx = idx
   return string[:prev_idx]