[llvm-dev] Different ways of running lit

Zachary Turner via llvm-dev llvm-dev at lists.llvm.org
Mon Sep 11 10:52:35 PDT 2017

I'm looking at ways of simplifying the lit config files.  Currently, almost
every lit.cfg and lit.site.cfg.in has a ton of copied code.  I kind of
understand why this is necessary architecturally now, so now I'm looking at
how to break it apart.

For example, every single lit config file has a block of code that looks
like this:

# Check that the object root is known.
if config.test_exec_root is None:
    # Otherwise, we haven't loaded the site specific configuration (the
user is
    # probably trying to run on a test file directly, and either the site
    # configuration hasn't been created by the build system, or we are in an
    # out-of-tree build situation).

    # Check for 'lit_site_config' user parameter, and use that if available.
    site_cfg = lit_config.params.get('lit_site_config', None)
    if site_cfg and os.path.exists(site_cfg):
        lit_config.load_config(config, site_cfg)
        raise SystemExit

    # Try to detect the situation where we are using an out-of-tree build by
    # looking for 'llvm-config'.
    # FIXME: I debated (i.e., wrote and threw away) adding logic to
    # automagically generate the lit.site.cfg if we are in some kind of
    # build situation. This means knowing how to invoke the build system
    # and I decided it was too much magic. We should solve this by just
    # the .cfg files generated during the configuration step.

    llvm_config = lit.util.which('llvm-config', config.environment['PATH'])
    if not llvm_config:
        lit_config.fatal('No site specific configuration available!')

    # Get the source and object roots.
    llvm_src_root = lit.util.capture(['llvm-config', '--src-root']).strip()
    llvm_obj_root = lit.util.capture(['llvm-config', '--obj-root']).strip()
    clang_src_root = os.path.join(llvm_src_root, "tools", "clang")
    clang_obj_root = os.path.join(llvm_obj_root, "tools", "clang")

    clang_tools_extra_src_root = os.path.join(clang_src_root, "tools",
    clang_tools_extra_obj_root = os.path.join(clang_obj_root, "tools",
    # Validate that we got a tree which points to here, using the standard
    # tools/clang layout.
    this_src_root = os.path.dirname(config.test_source_root)
    if os.path.realpath(clang_tools_extra_src_root) !=
        lit_config.fatal('No site specific configuration available!')

    # Check that the site specific configuration exists.
    site_cfg = os.path.join(clang_tools_extra_obj_root, 'test',
    if not os.path.exists(site_cfg):
            'No site specific configuration available! You may need to '
            'run "make test" in your Clang build directory.')

    # Okay, that worked. Notify the user of the automagic, and reconfigure.
    lit_config.note('using out-of-tree build at %r' % clang_obj_root)
    lit_config.load_config(config, site_cfg)
    raise SystemExit

It's obviously copy / pasted, as even the comments are the same.

This is not the only example either, probably 50% of lit.cfg files are copy
/ paste.  I'm trying to eliminate all of this.

Again, I already kind of understand the basic idea of what needs to be
done, I just want to make sure I'm testing all use cases.

On Mon, Sep 11, 2017 at 10:32 AM Matthias Braun <mbraun at apple.com> wrote:

> Maybe tell us what you want to change?
> Indeed lit is used in various ways outside of llvm.
> libcxx and the llvm test-suite both have a bigger amount of custom python
> code for their lit tests and break easily when changing lit.
> - Matthias
> > On Sep 10, 2017, at 10:32 PM, Zachary Turner via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> > What are all the different ways people run lit?  I'm doing some
> refactoring and want to make sure I have all the based covered.  Obviously
> you can use check-llvm.  And you can also run llvm-lit.py in your bin
> directory and point it to your source tree.
> >
> > What else?  Both of the aforementioned methods require running cmake
> first, is there any use case where someone runs lit without having run
> cmake first?  Or anything else I'm not thinking of?
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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