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

[Jessica Paquette via llvm-dev]

Right now, the tests try to accomplish the following

1. Define a sequence of instructions (e.g a,b,c)
2. Insert that sequence into k places with an unique instruction between them to make sure the outliner will yank them out *without overlaps*
3. Check for k calls to an outlined function
4. Check that the outlined sequence still exists in the program

This can result in some pretty long tests which would be a lot easier to define if we could say something like “this function must contain k instances of an outlined call, and not contain this sequence of instructions”.

test/CodeGen/machine-outliner.mir is a pretty good example of a test that would benefit from this sort of thing.

- Jessica

> On May 4, 2018, at 10:05 AM, Joel E. Denny <jdenny.ornl at gmail.com> wrote:
> 
> Hi Jessica,
> 
> This time I'm replying all....
> 
> On Fri, May 4, 2018 at 12:45 PM, Jessica Paquette <jpaquette at apple.com <mailto: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 <mailto: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 <mailto:llvm-dev at lists.llvm.org>
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev <http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> 
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20180507/37c034e7/attachment.html>