Michael137 wrote:
> > @dwblaikie @rnk It's been a minute but here's the "canonical lambda names
> > in debug-info" that we talked about in #159592
> > The interesting bit is the 3rd commit.
> > Before:
> > ```
> > // CHECK: !DISubprogram(name: "f1<(lambda at
> > {{.*}}simple-template-names.cpp:[[# @LINE - 2]]:17)>",
> > ```
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > After:
> > ```
> > // CHECK: !DISubprogram(name: "f1<f()::(lambda1)>",
> > ```
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Still in draft mode until I verify that this does the right thing for
> > namespace contexts too. Also getting some debug-info size numbers
>
> That looks plausible - this WIP is only for lambdas, not for anonymous
> structs/classes/enums, etc? Might be worth looking at those too to see if the
> design is amenable to addressing those too.
This patch should also work for non-lambda anonymous entities. I'll need to add
some tests for those
> Also, addressing the canonicalization problem is only part of the solution
> for being able to use this for Simplified Template Names - the other part
> would be needing to encode this data (like the mangling number) in the DWARF.
> I guess we could put this stable name (the unqualified version of it, at
> least) in the DW_AT_name of the lambda, it's /probably/ better than no name
> at all (though no name is more accurate).
Right good point. For now I wasn't focused on solving the simple-template-name
reconstitution issue for now. But definitely good to follow-up on this after
this lands. I'd have to think more about that but off the top your suggestion
re. DW_AT_name sounds reasonable (though will need to be careful with
debug-info size there).
> Did you check two lambdas with different signatures?
> https://godbolt.org/z/qsvbfTs1f - the lambdas in inline function `f1` get a
> mangling number unique to the signature (so two lambdas with different
> signatures both get the mangling number 1) whereas in f3 (an extern linkage
> function) get numbered 1 and 2 (just a different choice in mangling - since
> the lambdas in f3 don't have external linkage, they can have any name we
> choose and we choose non-signature-scoped-numbering (GCC uses the inline type
> example))
Yea i still need to elaborate on the test cases. The previous version of this
patch wasn't using the lambda mangling number (which is different from
non-lambda mangling number). Latest version of the patch aligns with GCC,
though will add more tests before marking for review. Thanks for taking a
preliminary look!
https://github.com/llvm/llvm-project/pull/168533
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