[U-Boot] policy regarding unused code

[Jean-Jacques Hiblot <jjhiblot@ti.com>]

>> I suspect this splits into three categories:
>> - Dead symbols and code to drop.
>> - Typos/thinkos
>> - Mistake in your grep?  I see CONFIG_VIRTIO_SANDBOX is used today for
>>    example.
>    what did you run to get that list of CONFIG_* symbols? years ago, i

This is small python script that I wrote (see code below).

What it does (roughly):

- scan all Makefile and*.mk file to create a set of variables starting 
with CONFIG_

- create the set of all used CONFIG_* variables by scanning 
moveconfig.db. This can be created with tools/moveconfig.py -b. (you 
need patch 'tools: moveconfig: Add an option to build a fuller database 
of options').

- subtract set#2 from set#1

JJ

From: Jean-Jacques Hiblot <jjhiblot@ti.com>
Date: Wed, 12 Dec 2018 16:15:21 +0100
Subject: [PATCH] simple tool to find unused options

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
---
  tools/find_unused_config_options.py | 78 
+++++++++++++++++++++++++++++++++++++
  1 file changed, 78 insertions(+)
  create mode 100755 tools/find_unused_config_options.py

diff --git a/tools/find_unused_config_options.py 
b/tools/find_unused_config_options.py
new file mode 100755
index 0000000..85c859a
--- /dev/null
+++ b/tools/find_unused_config_options.py
@@ -0,0 +1,78 @@
+#! /usr/bin/env python
+
+import re
+import os
+
+def get_var_from_moveconfig_db():
+       options = set()
+       search = re.compile("\s*CONFIG_([^=]*)=.*")
+       with open("moveconfig.db", "r") as f:
+               for l in f.readlines():
+                       m = search.match(l)
+                       if m:
+                               options.add(m.group(1))
+       return options
+
+def get_makefiles(start):
+       Makefiles = []
+       for (dirpath, dirnames, filenames) in os.walk(start):
+                Makefiles.extend([ os.path.join(dirpath,f) for f in 
filenames if f == "Makefile" or f.endswith(".mk")])
+       return Makefiles
+
+def get_C_files(start):
+       c_files = []
+       for (dirpath, dirnames, filenames) in os.walk(start):
+                Makefiles.extend([ os.path.join(dirpath,f) for f in 
filenames if f.endswith(".c") or f.endswith(".h")])
+       return c_files
+
+def get_CONFIG_var_from_Makefile(makefile):
+       simple_options = set()
+       spl_tpl_options = set()
+
+       search = re.compile("\$\(CONFIG_(.*)\)")
+       with open(makefile, "r") as f:
+               for l in f.readlines():
+                       m = search.search(l)
+                       if m:
+                               option = m.group(1)
+                               s = set()
+                               if option.startswith("$(SPL_)"):
+ s.add(option.replace("$(SPL_)",""))
+ s.add(option.replace("$(SPL_)","SPL_"))
+                               elif option.startswith("$(SPL_TPL_)"):
+ s.add(option.replace("$(SPL_TPL_)",""))
+ s.add(option.replace("$(SPL_TPL_)","SPL_"))
+ s.add(option.replace("$(SPL_TPL_)","TPL_"))
+                               else:
+ simple_options.add(option.split(')')[0].split(':')[0])
+                               for opt in s:
+ spl_tpl_options.add(opt.split(')')[0].split(':')[0])
+
+       return simple_options, spl_tpl_options
+
+
+makefiles = get_makefiles('./')
+simple_options = set()
+spl_tpl_options = set()
+for f in makefiles:
+       a, b = get_CONFIG_var_from_Makefile(f)
+       simple_options |= a
+       spl_tpl_options |= b
+
+var_in_makefiles = simple_options
+# add the SPL_TPL variables (but filter out those that are never 
referenced in the code)
+for option in spl_tpl_options:
+       ### filter out variable that are not reference at all
+       if os.system("git grep 'CONFIG_{}' > /dev/null".format(option)) 
== 0:
+               var_in_makefiles.add(option)
+
+var_in_cfg = get_var_from_moveconfig_db()
+
+whitelist = set(["SPL_BUILD","TPL_BUILD", "SHELL"])
+suspects = var_in_makefiles - var_in_cfg - whitelist
+
+print(" -----------------------")
+print ("used in makefile but NOT referenced in defconfigs")
+for option in suspects:
+       print('CONFIG_'+option)
+
-- 
2.7.4

>