[llvm-dev] [RFC] FileCheck: (dis)allowing unused prefixes

James Henderson via llvm-dev
2020-11-10T09:03:20Z

I don't know if lit's parser is up to this (I suspect it isn't), but
could
you add a comment to the end/in the middle of a RUN? Something like `# RUN:
do some thing | FileCheck %s --check-prefix=UNUSED --allow-unused-prefixes
## FIXME? That would avoid changing the line count. Alternatively, I'd just
fixup the tests as you go (i.e. change the expected line number, if they're
not huge in number). It may be obvious from reading whether or not the
prefix is intentionally unused, so you might even be able to skip the FIXME
annotation and just do the right thing.

On Mon, 9 Nov 2020 at 18:18, Mircea Trofin <mtrofin at google.com> wrote:

> There's a wrinkle in this: some tests (clang ones, for instance) have
> output checks depending on the line position of the input. For example,
> they check debug info. Adding // FIXME:  comments shift that.
>
> If the goal is easy identification of auto-inserted -allow-unused-prefixes
> directives, how about:
> - we make the flag an enum: true, false, and auto_inserted
> - we use -allow-unused-prefixes=auto_inserted for the scripts
>
> This allows easy identification, and should be easier to script without
> requiring more significant test by test surgery.
>
> WDYT?
>
> On Fri, Nov 6, 2020 at 7:13 AM Mircea Trofin <mtrofin at google.com>
wrote:
>
>> Oh! Perfect - thanks!
>>
>> (plus, if it becomes unsupported, there's another nudge to fix :) )
>>
>> On Fri, Nov 6, 2020 at 7:05 AM James Henderson <
>> jh7370.2008 at my.bristol.ac.uk> wrote:
>>
>>> I recently discovered that multi-line RUN statements can actually
be
>>> interrupted with non-RUN lines, without changing the behaviour. In
other
>>> words, you can do something like:
>>>
>>> # RUN: some command --option1 \
>>> ## Comment
>>> # CHECK: check something
>>> # RUN:     --option2
>>>
>>> And you'd end up with "some command --option1
--option2" being run. It's
>>> rather surprising behaviour, and not one I'd generally
recommend
>>> exercising, but maybe in this context it would be okay?
>>>
>>> On Fri, 6 Nov 2020 at 15:00, Mircea Trofin <mtrofin at
google.com> wrote:
>>>
>>>>
>>>>
>>>> On Fri, Nov 6, 2020 at 2:22 AM James Henderson <
>>>> jh7370.2008 at my.bristol.ac.uk> wrote:
>>>>
>>>>> I think it would make more sense to add it at each
individual call
>>>>> site. This ensures that all cases are fixed, rather than
just one in a
>>>>> file. It also ensures that in the (hopefully unlikely)
event that there are
>>>>> both intentional and unintentional use-cases within a file,
each one gets
>>>>> checked.
>>>>>
>>>>> That would be better indeed, but may be trickier to
automate - the
>>>> challenge, in my mind, comes from multi-line RUN statements,
but maybe I'm
>>>> missing something / maybe there aren't that many. If folks
have
>>>> suggestions, please don't hesitate to throw them my way!
>>>>
>>>> Thanks!
>>>>
>>>>
>>>>> On Thu, 5 Nov 2020 at 20:29, Mircea Trofin via llvm-dev
<
>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>
>>>>>> Thanks!
>>>>>>
>>>>>> On Thu, Nov 5, 2020 at 11:50 AM Fāng-ruì Sòng
<maskray at google.com>
>>>>>> wrote:
>>>>>>
>>>>>>> On Thu, Nov 5, 2020 at 11:36 AM David Blaikie via
llvm-dev
>>>>>>> <llvm-dev at lists.llvm.org> wrote:
>>>>>>> >
>>>>>>> >
>>>>>>> >
>>>>>>> > On Thu, Nov 5, 2020 at 10:46 AM Mircea Trofin
<mtrofin at google.com>
>>>>>>> wrote:
>>>>>>> >>
>>>>>>> >>
>>>>>>> >>
>>>>>>> >> On Thu, Nov 5, 2020 at 10:40 AM David
Blaikie <dblaikie at gmail.com>
>>>>>>> wrote:
>>>>>>> >>>
>>>>>>> >>>
>>>>>>> >>>
>>>>>>> >>> On Thu, Nov 5, 2020 at 7:30 AM Mircea
Trofin via llvm-dev <
>>>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>>> >>>>
>>>>>>> >>>> There are currently 1350
owner-less failures in the
>>>>>>> spreadsheet. These seem to be the larger areas
there.
>>>>>>> >>>>
>>>>>>> >>>> If you see an area you have
ownership or expertise in, please
>>>>>>> sign up for fixing the tests by Monday, Nov. 9.
>>>>>>> >>>>
>>>>>>> >>>> Otherwise, I will
"blanket-add" --allow-unused-prefixes=true to
>>>>>>> the remaining failing tests.
>>>>>>> >>>
>>>>>>> >>>
>>>>>>> >>> If/when you do that, probably worth
adding a comment at each
>>>>>>> site to clarify that this was added automatically,
not vetted/intentionally
>>>>>>> added by a human. Something like "// FIXME:
Verify that unused prefixes are
>>>>>>> used intentionally" or the like.
>>>>>>> >>
>>>>>>> >> Ack. or, we can grep for
-allow-unused-prefixes=true, wdyt?
>>>>>>> >
>>>>>>> >
>>>>>>> > Not sure I understand who/when
>>>>>>> <https://teams.googleplex.com/u/when> they
would grep for that?
>>>>>>>
>>>>>>
>>>>>> AAh! Nevermind me :) forgot that there are reasonable
cases using it.
>>>>>> Yes, it makes sense to add a FIXME, perhaps at the
start of each file
>>>>>>
>>>>>>
>>>>>>> >
>>>>>>> > I was suggesting adding an explicit "this
use of
>>>>>>> --allow-unused-prefixes=true hasn't been
confirmed as intentional" so that
>>>>>>> the backwards compatibility cases can be
distinguished from the intentional
>>>>>>> cases when someone is reading the test case, rather
than puzzling over why
>>>>>>> this flag was added (which looks intentional)
though the unused prefix may
>>>>>>> not make sense in that particular test. It'll
make it easier in the future
>>>>>>> when someone does look at the test for them to not
feel like they're being
>>>>>>> implicitly told "this use of unused prefixes
is intentional" (by the
>>>>>>> presence of an explicit flag requesting such
support) while staring at the
>>>>>>> test and not being able to see why someone
would've done that intentionally.
>>>>>>>
>>>>>>> Directly CCing some folks who can fix or find
people to fix some
>>>>>>> directories (*/AMDGPU, */X86, */OpenMP, */AArch64)
on
>>>>>>>
>>>>>>>
https://docs.google.com/spreadsheets/d/1o6q3XH1n3DDyyccnYZ_kVfhFbTDzC_S09e973_cwYuw/edit#gid=0
>>>>>>> After these big directories are cleaned up, the
remaining tests
>>>>>>> should
>>>>>>> be manageable in amount.
>>>>>>>
>>>>>>> How to reproduce:
>>>>>>>
>>>>>>> sed -i
'/allow-unused-prefixes/s/true/false/'
>>>>>>> llvm/utils/FileCheck/FileCheck.cpp
>>>>>>> git update-index --assume-unchanged
>>>>>>> llvm/utils/FileCheck/FileCheck.cpp
>>>>>>> ninja check-llvm   # or check-clang ...
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> >>>
>>>>>>> >>>
>>>>>>> >>>>
>>>>>>> >>>>
>>>>>>> >>>>
>>>>>>> >>>> On Fri, Oct 30, 2020 at 12:48 PM
Mircea Trofin <
>>>>>>> mtrofin at google.com> wrote:
>>>>>>> >>>>>
>>>>>>> >>>>> An update: as of 871d658c9ceb,
the flag is now available, if
>>>>>>> folks need to use it.
>>>>>>> >>>>>
>>>>>>> >>>>> On Thu, Oct 29, 2020 at 10:28
AM Mircea Trofin <
>>>>>>> mtrofin at google.com> wrote:
>>>>>>> >>>>>>
>>>>>>> >>>>>> Hello all,
>>>>>>> >>>>>>
>>>>>>> >>>>>> TL;DR; if you used
FileCheck --check-prefixes and you missed
>>>>>>> (misspelled, for instance) one of the prefixes in
your test, FileCheck
>>>>>>> silently ignores that and the test passes.
>>>>>>> >>>>>>
>>>>>>> >>>>>> 1579 tests have this
property.
>>>>>>> >>>>>>
>>>>>>> >>>>>>
>>>>>>> >>>>>> The details
>>>>>>> >>>>>>
========>>>>>>> >>>>>> Please refer to
https://reviews.llvm.org/D90281 and the
>>>>>>> discussion there for more details (make sure you
open "older changes" for
>>>>>>> full context)
>>>>>>> >>>>>>
>>>>>>> >>>>>> The problem is covered by
the TL;DR;.
>>>>>>> >>>>>>
>>>>>>> >>>>>> The proposal is to add an
explicit flag to FileCheck,
>>>>>>> --allow-unused-prefixes, to indicate whether the
current behavior is
>>>>>>> intended (for instance, jdoerfert contributed a
scenario where that is the
>>>>>>> case).
>>>>>>> >>>>>>
>>>>>>> >>>>>> We want the default
behavior to be 'strict', i.e.
>>>>>>> --allow-unused-prefixes=false. Doing that right now
would lead to 1500 test
>>>>>>> failures.
>>>>>>> >>>>>>
>>>>>>> >>>>>> To get there (thanks,
maskray, for suggestion), we propose we:
>>>>>>> >>>>>> * land D90281 where the
flag is introduced, but is flipped to
>>>>>>> match today's behavior
>>>>>>> >>>>>> * employ a 'busy
beavers' approach, where test maintainers
>>>>>>> patch their tests:
>>>>>>> >>>>>>   - either leveraging the
flag, to explicitly indicate that
>>>>>>> unused prefixes is intended (i.e. add
--allow-unused-patches=true); or
>>>>>>> >>>>>>   - fix the test (e.g.
maybe there was a misspelling
>>>>>>> issue/omission/etc).
>>>>>>> >>>>>>
>>>>>>> >>>>>> A spreadsheet with the
failing tests is available here [1].
>>>>>>> >>>>>>
>>>>>>> >>>>>> The request to the
community members is to please sign up for
>>>>>>> their respective area in the spreadsheet, and then
mark it completed when
>>>>>>> that's the case (yes/no in the respective
column).
>>>>>>> >>>>>>
>>>>>>> >>>>>> When all the tests are
fixed, we will then flip
>>>>>>> --allow-unused-prefixes to false by default.
>>>>>>> >>>>>>
>>>>>>> >>>>>> Meanwhile, please consider
leveraging the flag explicitly
>>>>>>> when you author new tests that use
--check-prefixes. That can be then
>>>>>>> cleaned up easily after we switch to the
'strict' behavior.
>>>>>>> >>>>>>
>>>>>>> >>>>>> Thanks!
>>>>>>> >>>>>>
>>>>>>> >>>>>> [1]
>>>>>>>
https://docs.google.com/spreadsheets/d/1o6q3XH1n3DDyyccnYZ_kVfhFbTDzC_S09e973_cwYuw/edit?usp=sharing
>>>>>>> >>>>
>>>>>>> >>>>
_______________________________________________
>>>>>>> >>>> LLVM Developers mailing list
>>>>>>> >>>> llvm-dev at lists.llvm.org
>>>>>>> >>>>
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>> >
>>>>>>> >
_______________________________________________
>>>>>>> > LLVM Developers mailing list
>>>>>>> > llvm-dev at lists.llvm.org
>>>>>>> >
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> 宋方睿
>>>>>>>
>>>>>> _______________________________________________
>>>>>> LLVM Developers mailing list
>>>>>> llvm-dev at lists.llvm.org
>>>>>>
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>
>>>>>
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