[llvm-dev] Jump Threading duplicates dbg.declare intrinsics for fragments, bug?

[Reid Kleckner via llvm-dev]

On Tue, Sep 19, 2017 at 8:40 AM, Adrian Prantl via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> > Later loop unroll comes and unrolls the loop and then suddenly we have
> two absolutely identical dbg.declares and the assert in addFragmentOffset()
> blows. Who's at fault?
>
> Without having read the code yet, my intuition says that the unroller
> should not be duplicating dbg.declares, only dbg.values.
>

I think it's a bug in both places: the backend should tolerate identical,
duplicate dbg.declares, and the loop unroller probably shouldn't duplicate
dbg.declare, since there is no point.

IR is supposed to be duplicatable unless it is marked noduplicate. That was
ultimately the fix we applied for PR33157, right?
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