//tools/binary_size: Change merge symbols to have their size as padding

tools/binary_size/linker_map_parser.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.
 
 import logging
 
 import models
 
 
 class MapFileParser(object):
@@ skipping 157 matching lines @@
                 elif name is None:
                   address_str2, name = self._ParsePossiblyWrappedParts(line, 2)
 
               if address_str == '0xffffffffffffffff':
                 # The section needs special handling (e.g., a merge section)
                 # It also generally has a large offset after it, so don't
                 # penalize the subsequent symbol for this gap (e.g. a 50kb gap).
                 # There seems to be no corelation between where these gaps occur
                 # and the symbols they come in-between.
                 # TODO(agrieve): Learn more about why this happens.
-                address = -1
-                if syms and syms[-1].address > 0:
-                  merge_symbol_start_address = syms[-1].end_address
-                merge_symbol_start_address += size
+                if address_str2:
+                  address = int(address_str2[2:], 16) - 1
+                elif syms and syms[-1].address > 0:
+                  # Merge sym with no second line showing real address.
+                  address = syms[-1].end_address
+                else:
+                  logging.warning('First symbol of section had address -1')
+                  address = 0
+
+                merge_symbol_start_address = address + size
               else:
                 address = int(address_str[2:], 16)
                 # Finish off active address gap / merge section.
                 if merge_symbol_start_address:
                   merge_size = address - merge_symbol_start_address
                   logging.debug('Merge symbol of size %d found at:\n  %r',
                                 merge_size, syms[-1])
+                  # Set size=0 so that it will show up as padding.
                   sym = models.Symbol(
-                      section_name, merge_size,
-                      address=merge_symbol_start_address,
+                      section_name, 0,
+                      address=address,
                       name='** symbol gap %d' % symbol_gap_count,
                       object_path=path)
                   symbol_gap_count += 1
                   syms.append(sym)
                   merge_symbol_start_address = 0
 
-              if address == -1 and address_str2:
-                address = int(address_str2[2:], 16) - 1
-              # Merge sym with no second line showing real address.
-              if address == -1:
-                address = syms[-1].end_address
               syms.append(models.Symbol(section_name, size, address=address,
                                         name=name or mangled_name,
                                         object_path=path))
           logging.debug('Symbol count for %s: %d', section_name,
                         len(syms) - sym_count_at_start)
       except:
         logging.error('Problem line: %r', line)
         logging.error('In section: %r', section_name)
         raise