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

David Blaikie via llvm-dev
2020-11-09T21:53:59Z

On Mon, Nov 9, 2020 at 10:18 AM Mircea Trofin via llvm-dev
<llvm-dev at lists.llvm.org> 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.

Got a sense of roughly how many are like this? (have you found a lot,
or so far just a few?) FileCheck has mechanism for referencing the
current (& relative) line numbers which can help make tests like this
more flexible - if it's only a few I'd be in favor of improving the
tests to use that sort of thing.

> 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?

Not hugely in favor, but plausible - I'd probably use a long/fairly
explanatory name, but don't have great ideas for what that'd be.
"-allow-unused-prefixes=allowed_by_cleanup_please_check_if_usage_is_intentional"
or something.

>
> 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 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
>>>>>>> >
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>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> 宋方睿
>>>>>>
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>>>>>>
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