[PATCH] D16263: [CodeGenPrepare] Also consider metadata uses

[Keno Fischer via llvm-commits]

DWARF may describe locations, but LLVM IR describes values and just happens
to reuse the DWARF opcodes for it's expressions.

On Wed, Jan 20, 2016 at 8:37 PM, Adrian Prantl <aprantl at apple.com> wrote:

>
> > On Jan 16, 2016, at 9:01 PM, Keno Fischer <kfischer at college.harvard.edu>
> wrote:
> >
> > loladiro added a comment.
> >
> > Yeah, I was fearing something like that, although I had hoped that since
> this won't actually show  up in the generated assembly (or at least it
> shouldn't), it might be ok. In any case, I don't think this is
> representable in debug info currently without having an actual trunc
> instruction. We could modify the DIExpression to be able to express
> truncation, but that's somewhat tricky, since DWARF does not have such an
> operation. @aprantl, thoughts?
>
> Is the problem the Verifier? Because DWARF expressions are supposed to
> describe the location of a value rather than the value a truncation
> operation doesn’t necessarily make sense.
>
> -- adrian
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