On Wed, Dec 19, 2018 at 8:40 AM Tom Roeder <tmroeder@xxxxxxxxxx> wrote: > > The LLVM/Clang project provides many tools for analyzing C source code. > Many of these tools are based on LibTooling > (https://clang.llvm.org/docs/LibTooling.html), which depends on a > database of compiler flags. The standard container for this database is > compile_commands.json, which consists of a list of JSON objects, each > with "directory", "file", and "command" fields. > > Some build systems, like cmake or bazel, produce this compilation > information directly. Naturally, Makefiles don't. However, the kernel > makefiles already create .<target>.o.cmd files that contain all the > information needed to build a compile_commands.json file. > > So, this commit adds scripts/gen_compile_commands.py, which recursively > searches through a directory for .<target>.o.cmd files and extracts > appropriate compile commands from them. It writes a > compile_commands.json file that LibTooling-based tools can use. > > By default, gen_compile_commands.py starts its search in its working > directory and (over)writes compile_commands.json in the working > directory. However, it also supports --output and --directory flags for > out-of-tree use. > > Note that while gen_compile_commands.py enables the use of clang-based > tools, it does not require the kernel to be compiled with clang. E.g., > the following sequence of commands produces a compile_commands.json file > that works correctly with LibTooling. > > make defconfig > make > scripts/gen_compile_commands.py > > Also note that this script is written to work correctly in both Python 2 > and Python 3, so it does not specify the Python version in its first > line. > > For an example of the utility of this script: after running > gen_compile_commands.json on the latest kernel version, I was able to > use Vim + the YouCompleteMe pluging + clangd to automatically jump to > definitions and declarations. Obviously, cscope and ctags provide some > of this functionality; the advantage of supporting LibTooling is that it > opens the door to many other clang-based tools that understand the code > directly and do not rely on regular expressions and heuristics. > > Tested: Built several recent kernel versions and ran the script against > them, testing tools like clangd (for editor/LSP support) and clang-check > (for static analysis). Also extracted some test .cmd files from a kernel > build and wrote a test script to check that the script behaved correctly > with all permutations of the --output and --directory flags. > > Signed-off-by: Tom Roeder <tmroeder@xxxxxxxxxx> > --- > Changelog since v1: > - Add simple string replacement to unescape the pound sign. Applied to linux-kbuild. Thanks! -- Best Regards Masahiro Yamada
