[gcmole] Re-write gcmole runner in Python

This removes the dependency on Lua for running gcmole, and Python's
expressiveness lets us clean up the code a bit, including getting rid
of global variables, embedding the multiprocessing (removing the need
for a separate `parallel.py`), and using difflib for printing the test
expectation diff.

Bug: v8:11169, v8:8590, chromium:1097212
Change-Id: If0ab5ea6f764864855d73cd0ba63cb37c1823955
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2543927
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Liviu Rau <liviurau@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71253}

tools/gcmole/BUILD.gn

@@ -8,12 +8,10 @@ group("v8_run_gcmole") {
   testonly = true
 
   data = [
-    "gccause.lua",
     "GCMOLE.gn",
-    "gcmole.lua",
+    "gcmole.py",
     "gcmole-test.cc",
     "gcmole-tools/",
-    "parallel.py",
     "run-gcmole.py",
     "suspects.whitelist",
     "ignored_files",

tools/gcmole/bootstrap.sh

@@ -117,5 +117,5 @@ set +x
 echo
 echo You can now run gcmole using this command:
 echo
-echo CLANG_BIN=\"tools/gcmole/gcmole-tools/bin\" lua tools/gcmole/gcmole.lua
+echo CLANG_BIN=\"tools/gcmole/gcmole-tools/bin\" python tools/gcmole/gcmole.py
 echo

tools/gcmole/gccause.lua

--- Copyright 2011 the V8 project authors. All rights reserved.
--- Redistribution and use in source and binary forms, with or without
--- modification, are permitted provided that the following conditions are
--- met:
---
---     * Redistributions of source code must retain the above copyright
---       notice, this list of conditions and the following disclaimer.
---     * Redistributions in binary form must reproduce the above
---       copyright notice, this list of conditions and the following
---       disclaimer in the documentation and/or other materials provided
---       with the distribution.
---     * Neither the name of Google Inc. nor the names of its
---       contributors may be used to endorse or promote products derived
---       from this software without specific prior written permission.
---
--- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
--- "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
--- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
--- A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
--- OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
--- SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
--- LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
--- DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
--- THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
--- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
--- OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
--- This is an auxiliary tool that reads gccauses file generated by
--- gcmole.lua and prints tree of the calls that can potentially cause a GC
--- inside a given function.
---
--- Usage: lua tools/gcmole/gccause.lua <function-name-pattern>
---
-
-assert(loadfile "gccauses")()
-
-local P = ...
-
-local T = {}
-
-local function TrackCause(name, lvl)
-   io.write(("  "):rep(lvl or 0), name, "\n")
-   if GC[name] then
-      local causes = GC[name]
-      for i = 1, #causes do
-	 local f = causes[i]
-	 if not T[f] then
-	    T[f] = true
-	    TrackCause(f, (lvl or 0) + 1)
-	 end
-
-	 if f == '<GC>' then break end
-      end
-   end
-end
-
-for name, _ in pairs(GC) do
-   if name:match(P) then
-      T = {}
-      TrackCause(name)
-   end
-end

tools/gcmole/package.sh

@@ -49,5 +49,5 @@ echo $(readlink -f "${PACKAGE_FILE}")
 echo
 echo You can now run gcmole using this command:
 echo
-echo CLANG_BIN=\"tools/gcmole/gcmole-tools/bin\" lua tools/gcmole/gcmole.lua
+echo CLANG_BIN=\"tools/gcmole/gcmole-tools/bin\" python tools/gcmole/gcmole.py
 echo

tools/gcmole/parallel.py

-#!/usr/bin/env python
-# Copyright 2015 the V8 project authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-"""
-This script calls the first argument for each of the following arguments in
-parallel. E.g.
-parallel.py "clang --opt" file1 file2
-calls
-clang --opt file1
-clang --opt file2
-
-The output (stdout and stderr) is concatenated sequentially in the form:
-______________ file1
-<output of clang --opt file1>
-______________ finish <exit code of clang --opt file1> ______________
-______________ file2
-<output of clang --opt file2>
-______________ finish <exit code of clang --opt file2> ______________
-"""
-
-# for py2/py3 compatibility
-from __future__ import print_function
-
-import itertools
-import multiprocessing
-import subprocess
-import sys
-
-def invoke(cmdline):
-  try:
-    return (subprocess.check_output(
-        cmdline, shell=True, stderr=subprocess.STDOUT), 0)
-  except subprocess.CalledProcessError as e:
-    return (e.output, e.returncode)
-
-if __name__ == '__main__':
-  assert len(sys.argv) > 2
-  processes = multiprocessing.cpu_count()
-  pool = multiprocessing.Pool(processes=processes)
-  cmdlines = ["%s %s" % (sys.argv[1], filename) for filename in sys.argv[2:]]
-  for filename, result in itertools.izip(
-      sys.argv[2:], pool.imap(invoke, cmdlines)):
-    print("______________ %s" % filename)
-    print(result[0])
-    print("______________ finish %d ______________" % result[1])

tools/gcmole/run-gcmole.py

@@ -15,19 +15,18 @@ import sys
 GCMOLE_PATH = os.path.dirname(os.path.abspath(__file__))
 CLANG_BIN = os.path.join(GCMOLE_PATH, 'gcmole-tools', 'bin')
 CLANG_PLUGINS = os.path.join(GCMOLE_PATH, 'gcmole-tools')
-LUA = os.path.join(GCMOLE_PATH, 'gcmole-tools', 'lua52')
-DRIVER = os.path.join(GCMOLE_PATH, 'gcmole.lua')
+DRIVER = os.path.join(GCMOLE_PATH, 'gcmole.py')
 BASE_PATH = os.path.dirname(os.path.dirname(GCMOLE_PATH))
 
-assert len(sys.argv) == 2
+assert len(sys.argv) >= 2
 
 if not os.path.isfile("out/build/gen/torque-generated/builtin-definitions.h"):
   print("Expected generated headers in out/build/gen.")
-  print("Either build v8 in out/build or change gcmole.lua:115")
+  print("Either build v8 in out/build or change the 'out/build/gen' location in gcmole.py")
   sys.exit(-1)
 
 proc = subprocess.Popen(
-    [LUA, DRIVER, sys.argv[1]],
+    ["python", DRIVER] + sys.argv[1:],
     env={'CLANG_BIN': CLANG_BIN, 'CLANG_PLUGINS': CLANG_PLUGINS},
     cwd=BASE_PATH,
 )