supersize: Fix --toolprefix="" not being followed

tools/binary_size/libsupersize/archive.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.
 
 """Main Python API for analyzing binary size."""
 
 import argparse
 import calendar
 import collections
 import datetime
@@ skipping 531 matching lines @@
   # Matches  [ 2] .hash HASH 00000000006681f0 0001f0 003154 04   A  3   0  8
   for match in re.finditer(r'\[[\s\d]+\] (\..*)$', stdout, re.MULTILINE):
     items = match.group(1).split()
     section_sizes[items[0]] = int(items[4], 16)
   return section_sizes
 
 
 def _ArchFromElf(elf_path, tool_prefix):
   args = [tool_prefix + 'readelf', '-h', elf_path]
   stdout = subprocess.check_output(args)
-  return re.search('Machine:\s*(\S+)', stdout).group(1)
+  machine = re.search('Machine:\s*(.+)', stdout).group(1)
+  if machine == 'Intel 80386':
+    return 'x86'
+  if machine == 'Advanced Micro Devices X86-64':
+    return 'x64'
+  elif machine == 'ARM':
+    return 'arm'
+  elif machine == 'AArch64':
+    return 'arm64'
+  return machine
 
 
 def _ParseGnArgs(args_path):
   """Returns a list of normalized "key=value" strings."""
   args = {}
   with open(args_path) as f:
     for l in f:
       # Strips #s even if within string literal. Not a problem in practice.
       parts = l.split('#')[0].split('=')
       if len(parts) != 2:
@@ skipping 94 matching lines @@
     if apk_path:
       logging.debug('Extracting section sizes from .so within .apk')
       unstripped_section_sizes = size_info.section_sizes
       apk_build_id, size_info.section_sizes = apk_elf_result.get()
       assert apk_build_id == metadata[models.METADATA_ELF_BUILD_ID], (
           'BuildID for %s within %s did not match the one at %s' %
           (apk_so_path, apk_path, elf_path))
 
       packed_section_name = None
       architecture = metadata[models.METADATA_ELF_ARCHITECTURE]
-      if architecture == 'ARM':
+      # Packing occurs enabled only arm32 & arm64.
+      if architecture == 'arm':
         packed_section_name = '.rel.dyn'
-      elif architecture == 'AArch64':
+      elif architecture == 'arm64':
         packed_section_name = '.rela.dyn'
 
       if packed_section_name:
         logging.debug('Recording size of unpacked relocations')
         if packed_section_name not in size_info.section_sizes:
           logging.warning('Packed section not present: %s', packed_section_name)
         else:
           size_info.section_sizes['%s (unpacked)' % packed_section_name] = (
               unstripped_section_sizes.get(packed_section_name))
 
   logging.info('Recording metadata: \n  %s',
                '\n  '.join(describe.DescribeMetadata(size_info.metadata)))
   logging.info('Saving result to %s', args.size_file)
   file_format.SaveSizeInfo(size_info, args.size_file)
   logging.info('Done')