[PATCH] D53710: [FileCheck] Warn if a prefix is only used in LABEL checks

[Paul Robinson via Phabricator via llvm-commits]

probinson added a comment.

In https://reviews.llvm.org/D53710#1290345, @jdenny wrote:

> In https://reviews.llvm.org/D53710#1289937, @SjoerdMeijer wrote:
>
> > > AMDGPU does this a lot intentionally for a shared label prefix and unique per run like ones for different subtargets
> >
> > Yep.  Briefly looked at AMDGPU warnings. The very first 4 warnings, in tests `basic-loop.ll`, `basic-call-return.ll`, `bug-vopc-commute.ll`, `call-return-types.ll`, shows I think that they are dodgy tests, but then I see indeed the intentional use of the shared label prefix.
>
>
> You two seem to be saying that the concept of a "shared label prefix" justifies this use case.  I'm sorry, but I don't know what that phrase means.  Could someone please explain?  In other words, couldn't these tests just use "CHECK:" (or "GCN:" or whatever prefix they prefer) without "-LABEL"?  I believe that's Paul's position.


I think a concrete example would help, and it looks like CodeGen/AMDGPU/cttz_zero_undef.ll is one.  In this test, there are three RUN lines, each for a different subtarget, and the check-prefix options include FUNC and also some subtarget-specific prefixes.  Then you have checks like

  ; FUNC-LABEL: {{^}}s_cttz_zero_undef_i32:
  ; SI: something
  ; EG: some other thing
  ; FUNC-LABEL: {{^}}v_cttz_zero_undef_i32:
  ; SI: thing3
  ; EG: thing4

So the FUNC prefix is used just for the LABELs, and other prefixes are used for target-specific variations within each test function.

This seems like a reasonable use-case to me.


https://reviews.llvm.org/D53710