[LLVMdev] [llvm-commits] [PATCH] A "very verbose" mode for FileCheck

Thu Jan 17 11:19:46 PST 2013

On Thu, Jan 17, 2013 at 10:59 AM, David Blaikie <dblaikie at gmail.com> wrote:

> On Thu, Jan 17, 2013 at 10:51 AM, Daniel Dunbar <daniel at zuster.org> wrote:
> > Note that as far as places to put temporary files, the right place to put
> > them is alongside the other test outputs in the test output "sandbox"
> > directory.
> >
> > Somewhat orthogonal, but we should also fix up lit to purge those
> sandboxes
> > before it starts a new test run.
>
> SGTM - though if we are going to go with the plan/features you've
> outlined, it might not be so unreasonable to, rather than tunnelling
> the log files through the lit output & splitting them back out, do the
> work to actually gather those log files directly (it's a bit more work
> in the buildbot configuration - enough that I didn't think I could
> justify it given Dmitri's original proposal - but seems like it would
> simplify this change & leave us roughly where I was discussing earlier
> (though your suggestion of generalizing this over all of lit, rather
> than just FileCheck is a step beyond what I'd proposed - it sounds
> good/right though))
>

I'm fine not having the files dumped into the output, but I at least want
the buildbot to get the names of the files to collect from the lit output,
not just by scanning the folder.

I asked about how to do this in the freenode buildbot channel & they
> mentioned that it is possible to name log files dynamically to be
> retrieved from the slave - I haven't looked into it in detail because
> it did sound a bit more complicated, but should be achievable.
>

Yes, it is possible. I can help with the buildbot implementation if need be.

> The drawback to your approach is that we'd have to enable this feature
> unconditionally - rather than having the optimization advantage of
> only dumping files on failure (see my question earlier in the thread,
> Eli's concern that dumping output would be expensive, and Dmitri's
> response that we'd only be dumping on failure anyway). Given that it
> seems the vast majority of our failures aren't flakey, we could have
> lit setup to rerun failures in a "create all the temporary files"
> mode, though missing flakes would be unfortunate.
>

In my experience, there isn't actually that much performance difference
(and sometimes a loss) of using a file instead of a pipe. With all the
other stuff going on in the test suite I would be surprised if this added
much impact. Note that I personally often write my tests to use temporary
files instead of pipes anyway just because I like how the RUN lines look,
so its not exactly like we aren't already storing many of these files.

There would be some code simplification advantages internally to lit too if
it avoided actually using pipes, although I'm not sure I want to go as far
as dropping that support.

If it is measurable, then my proposal is to do as you say and just rerun
the test with the collection enabled. I actually think that lit by default
should rerun failing tests so that it can diagnose flaky tests, so this
fits in with that.

 - Daniel

> >
> >  - Daniel
> >
> >
> > On Wed, Jan 16, 2013 at 3:31 PM, Dmitri Gribenko <gribozavr at gmail.com>
> > wrote:
> >>
> >> On Thu, Jan 17, 2013 at 1:23 AM, Evgeniy Stepanov
> >> <eugeni.stepanov at gmail.com> wrote:
> >> > On Thu, Jan 17, 2013 at 1:19 AM, Dmitri Gribenko <gribozavr at gmail.com
> >
> >> > wrote:
> >> >> On Wed, Jan 16, 2013 at 9:33 PM, Dmitri Gribenko <
> gribozavr at gmail.com>
> >> >> wrote:
> >> >>> On Wed, Jan 16, 2013 at 9:24 PM, Chris Lattner <clattner at apple.com>
> >> >>> wrote:
> >> >>>>
> >> >>>> On Jan 16, 2013, at 10:32 AM, Dmitri Gribenko <gribozavr at gmail.com
> >
> >> >>>> wrote:
> >> >>>>
> >> >>>>> Hello,
> >> >>>>>
> >> >>>>> When someone breaks a FileCheck-based test on some buildbot,
> >> >>>>> sometimes
> >> >>>>> it may not be obvious *why* did it fail.  If the failure can not
> be
> >> >>>>> reproduced locally, it can be very hard to fix.
> >> >>>>>
> >> >>>>> I propose adding a "very verbose" mode to FileCheck.  In this mode
> >> >>>>> FileCheck will dump the input file in case of failure.  This mode
> >> >>>>> will
> >> >>>>> be enabled by an environment variable "FILECHECK_VERY_VERBOSE".
>  If
> >> >>>>> we
> >> >>>>> chose a command line option, we would have to edit all
> >> >>>>> FileCheck-based
> >> >>>>> tests to use %FileCheck.
> >> >>>>
> >> >>>> I think that this idea is good, but I'd prefer it be implemented a
> >> >>>> different way:
> >> >>>>
> >> >>>>  - Filecheck should take a new flag -dump-input-on-error that
> causes
> >> >>>> it to... dump the input file on error.
> >> >>>>  - Lit should be the thing that checks the environment (or perhaps
> >> >>>> add a new option to lit), and adds the flag to FileCheck
> invocations.
> >> >>>>
> >> >>>> I don't like it when the behavior of such a low-level tool like
> this
> >> >>>> changes based on environment variables.  It isn't discoverable in
> --help.
> >> >>>> If for some reason, it is bad for lit to implicitly pass the
> option, I'd
> >> >>>> rather have a standard FILECHECK_COMMANDLINE environment variable,
> and have
> >> >>>> filecheck parse arbitrary options out of it using the
> >> >>>> cl::ParseEnvironmentOptions function.
> >> >>>
> >> >>> I agree that a command line option would be better.  But in that
> case
> >> >>> all tests should be updated.  It is not an issue for me -- it is
> >> >>> mostly mechanical.  So should I change tests to use %FileCheck?
> >> >>
> >> >> Here's a third attempt.
> >> >>
> >> >> The new behavior is as follows:
> >> >>
> >> >> 1. In case of errors we always dump output to a temporary file and
> >> >> print
> >> >
> >> > Does it mean we get one more file in /tmp every time a test fails, and
> >> > it is not cleaned up automatically? I don't think this should happen
> >> > in the "default" mode of the tool.
> >>
> >> Well, yes.  David requested that and I agreed that it is a good idea.
> >> Are you strongly opposed to it?
> >>
> >> Dmitri
> >>
> >> --
> >> main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
> >> (j){printf("%d\n",i);}}} /*Dmitri Gribenko <gribozavr at gmail.com>*/
> >>
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> >
> >
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