supersize: Make Disassemble() work for downloaded .size files

tools/binary_size/libsupersize/console.py

Index: tools/binary_size/libsupersize/console.py
diff --git a/tools/binary_size/libsupersize/console.py b/tools/binary_size/libsupersize/console.py
index f019564557333c337a84594bc8f2436226ef2484..1e87f44416577c38177b03c8bea61c15832b71c8 100644
--- a/tools/binary_size/libsupersize/console.py
+++ b/tools/binary_size/libsupersize/console.py
@@ -66,7 +66,7 @@ def _WriteToStream(lines, use_pager=None, to_file=None):
 class _Session(object):
   _readline_initialized = False
 
-  def __init__(self, size_infos, lazy_paths):
+  def __init__(self, size_infos, size_paths, lazy_paths):
     self._variables = {
         'Print': self._PrintFunc,
         'Diff': self._DiffFunc,
@@ -77,6 +77,8 @@ class _Session(object):
     }
     self._lazy_paths = lazy_paths
     self._size_infos = size_infos
+    self._size_paths = size_paths
+    self._disassemble_prefix_len = None
 
     if len(size_infos) == 1:
       self._variables['size_info'] = size_infos[0]
@@ -119,23 +121,71 @@ class _Session(object):
     lines = describe.GenerateLines(obj, verbose=verbose, recursive=recursive)
     _WriteToStream(lines, use_pager=use_pager, to_file=to_file)
 
-  def _ElfPathForSymbol(self, symbol):
+  def _ElfPathAndToolPrefixForSymbol(self, symbol, elf_path, tool_prefix):
     size_info = None
-    for size_info in self._size_infos:
+    size_path = None
+    for size_info, size_path in zip(self._size_infos, self._size_paths):
       if symbol in size_info.symbols:
         break
     else:
-      assert False, 'Symbol does not belong to a size_info.'
-
-    filename = size_info.metadata.get(models.METADATA_ELF_FILENAME)
-    output_dir = self._lazy_paths.output_directory or ''
-    path = os.path.normpath(os.path.join(output_dir, filename))
-
-    found_build_id = archive.BuildIdFromElf(path, self._lazy_paths.tool_prefix)
+      # If symbols is from a diff(), use its address+name to find it.
+      for size_info, size_path in zip(self._size_infos, self._size_paths):
+        matched = size_info.symbols.WhereAddressInRange(symbol.address)
+        # Use last matched symbol to skip over padding-only symbols.
+        if len(matched) > 0 and matched[-1].full_name == symbol.full_name:
+          symbol = matched[-1]
+          break
+      else:
+        assert False, 'Symbol does not belong to a size_info.'
+
+    orig_tool_prefix = size_info.metadata.get(models.METADATA_TOOL_PREFIX)
+    if orig_tool_prefix:
+      orig_tool_prefix = paths.FromSrcRootRelative(orig_tool_prefix)
+      if os.path.exists(orig_tool_prefix + 'objdump'):
+        tool_prefix = orig_tool_prefix
+
+    # TODO(agrieve): Would be even better to use objdump --info to check that
+    #     the toolchain is for the correct architecture.
+    assert tool_prefix is not None, (
+        'Could not determine --tool-prefix. Possible fixes include setting '
+        '--tool-prefix, or setting --output-directory')
+
+    if elf_path is None:
+      filename = size_info.metadata.get(models.METADATA_ELF_FILENAME)
+      output_dir = self._lazy_paths.output_directory
+      size_path = self._size_paths[self._size_infos.index(size_info)]
+      if output_dir:
+        # Local build: File is located in output directory.
+        path = os.path.normpath(os.path.join(output_dir, filename))
+      if not output_dir or not os.path.exists(path):
+        # Downloaded build: File is located beside .size file.
+        path = os.path.normpath(os.path.join(
+            os.path.dirname(size_path), os.path.basename(filename)))
+
+      assert os.path.exists(path), (
+          'Could locate ELF file. If binary was built locally, ensure '
+          '--output-directory is set. If output directory is unavailable, '
+          'ensure {} is located beside {}, or pass its path explicitly using '
+          'elf_path=').format(os.path.basename(filename), size_path)
+
+    found_build_id = archive.BuildIdFromElf(path, tool_prefix)
     expected_build_id = size_info.metadata.get(models.METADATA_ELF_BUILD_ID)
     assert found_build_id == expected_build_id, (
         'Build ID does not match for %s' % path)
-    return path
+    return path, tool_prefix
+
+  def _DetectDisassemblePrefixLen(self, args):
+    # Look for a line that looks like:
+    # /usr/{snip}/src/out/Release/../../net/quic/core/quic_time.h:100
+    output = subprocess.check_output(args)
+    for line in output.splitlines():
+      if line and line[0] == os.path.sep and line[-1].isdigit():
+        release_idx = line.find('Release')
+        if release_idx == -1:
+          break
+        return line.count(os.path.sep, 0, release_idx)
+    logging.warning('Found no source paths in objdump output.')
+    return None
 
   def _DisassembleFunc(self, symbol, elf_path=None, use_pager=None,
                        to_file=None):
@@ -147,13 +197,34 @@ class _Session(object):
           when auto-detection fails.
     """
     assert symbol.address and symbol.section_name == '.text'
-    if not elf_path:
-      elf_path = self._ElfPathForSymbol(symbol)
+
     tool_prefix = self._lazy_paths.tool_prefix
+    if not elf_path:
+      elf_path, tool_prefix = self._ElfPathAndToolPrefixForSymbol(
+          symbol, elf_path, tool_prefix)
+
     args = [tool_prefix + 'objdump', '--disassemble', '--source',
             '--line-numbers', '--demangle',
             '--start-address=0x%x' % symbol.address,
             '--stop-address=0x%x' % symbol.end_address, elf_path]
+    if self._disassemble_prefix_len is None:
+      prefix_len = self._DetectDisassemblePrefixLen(args)
+      if prefix_len is not None:
+        self._disassemble_prefix_len = prefix_len
+
+    if self._disassemble_prefix_len is not None:
+      output_directory = self._lazy_paths.output_directory
+      # Only matters for non-generated paths, so be lenient here.
+      if output_directory is None:
+        output_directory = os.path.join(paths.SRC_ROOT, 'out', 'Release')
+        if not os.path.exists(output_directory):
+          os.makedirs(output_directory)
+
+      args += [
+          '--prefix-strip', str(self._disassemble_prefix_len),
+          '--prefix', os.path.normpath(os.path.relpath(output_directory))
+      ]
+
     proc = subprocess.Popen(args, stdout=subprocess.PIPE)
     lines = itertools.chain(('Showing disassembly for %r' % symbol,
                              'Command: %s' % ' '.join(args)),
@@ -174,7 +245,7 @@ class _Session(object):
         '# Show two levels of .text, grouped by first two subdirectories',
         'text_syms = size_info.symbols.WhereInSection("t")',
         'by_path = text_syms.GroupedByPath(depth=2)',
-        'Print(by_path.WhereBiggerThan(1024))',
+        'Print(by_path.WherePssBiggerThan(1024))',
         '',
         '# Show all non-vtable generated symbols',
         'generated_syms = size_info.symbols.WhereGeneratedByToolchain()',
@@ -276,7 +347,7 @@ def Run(args, parser):
   lazy_paths = paths.LazyPaths(tool_prefix=args.tool_prefix,
                                output_directory=args.output_directory,
                                any_path_within_output_directory=args.inputs[0])
-  session = _Session(size_infos, lazy_paths)
+  session = _Session(size_infos, args.inputs, lazy_paths)
 
   if args.query:
     logging.info('Running query from command-line.')