[llvm-dev] RFC: [FileCheck] CHECK-DAG for multiple occurrences of string

[Joel E. Denny via llvm-dev]

Hi Jessica,

This time I'm replying all....

On Fri, May 4, 2018 at 12:45 PM, Jessica Paquette <jpaquette at apple.com>
wrote:

> I would personally like a feature like that in FileCheck because it would
> make it a lot easier to write MachineOutliner tests, and would make the
> tests significantly smaller and easier to understand.
>

How do MachineOutliner tests accomplish this now?  Can you point me to an
example?

Thanks.

Joel


>
> - Jessica
>
> > On May 4, 2018, at 8:40 AM, Joel E. Denny via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> > Hi,
> >
> > Using FileCheck, I have not found a way to make a group of CHECK-DAG
> directives match multiple occurrences of a string.  For example, I naively
> thought the following would match successfully:
> >
> > ```
> > $ cat checks.txt
> > // CHECK: start
> > // CHECK-DAG: foo
> > // CHECK-DAG: foo
> > // CHECK-DAG: bar
> > // CHECK-NEXT: end
> >
> > $ cat input.txt
> > start
> > foo
> > bar
> > foo
> > end
> >
> > $ FileCheck --input-file=input.txt checks.txt
> > checks.txt:5:16: error: CHECK-NEXT: is not on the line after the
> previous match
> > // CHECK-NEXT: end
> >                ^
> > input.txt:5:1: note: 'next' match was here
> > end
> > ^
> > input.txt:3:4: note: previous match ended here
> > bar
> >    ^
> > input.txt:4:1: note: non-matching line after previous match is here
> > foo
> > ^
> > ```
> >
> > The trouble is that both "CHECK-DAG: foo" directives match the first
> "foo".
> >
> > I'd like this ability for testing a parallel program that outputs a
> series of non-unique strings in non-deterministic order.  Am I trying to
> push FileCheck beyond its intended domain?  Is there some existing feature
> for this purpose that I've overlooked?  If not, I see two potential
> solutions:
> >
> > 1. In a CHECK-DAG group, don't let the matches for patterns overlap.
> >
> > 2. Add a new CHECK-DAG-N directive, where N is some integer, to express
> that a pattern must have N non-overlapping matches.
> >
> > An advantage of #1 that the intuitive way (at least in my mind) of
> expressing multiple occurrences of a string, as in the example above, would
> work.  An advantage of #2 is that existing CHECK-DAG functionality would
> not change, and so there should be no chance of impacting existing well
> formed tests.
> >
> > To understand the issue better, I've prototyped #2.  It still needs test
> cases and documentation, so it's not ready for a formal patch review.  If
> people like the idea, I'll polish it up.
> >
> > Thanks.
> >
> > Joel
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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