[llvm-dev] [RFC] - Deduplication of debug information in linkers (LLD).

[David Blaikie via llvm-dev]

On Fri, Dec 15, 2017 at 7:47 AM George Rimar <grimar at accesssoftek.com>
wrote:

> >Not quite sure what you mean by "on linker side" - but I guess you mean
> using linker features like comdats etc, rather than DWARF
> parsing/reassembly/etc.
>
>
> I mean that it probably not a good idea for external library. I feel it
> is much more convinent to do such proccessing in a linker.
>
Ah, a matter of where the logic is implemented.

My concern is that we already have one use of this logic (dsymutil) and at
least two other places that could benefit from it (lld and dwp) - it would
seem unfortunate to build and maintain 3 separate versions of this.

(also, possibly one day, a 4th place: llvm IR linking - it could be useful
to generate type DWARF (& CodeView) from frontends rather than backends,
then do a full DWARF aware linking of it in the llvm linking step)

But all of that's probably a bit of a long way off I imagine, in terms of
getting the initial idea (should lld grow/have DWARF aware linking
functionality) going.

> Linker do and knows much more about things like sections that are ICFed,
> eliminated, about COMDATs and many things like strings dedups.
>
> So it can rebuild relocations and perform DWARF deduplication probably in
> a faster/more convinent way probably than external API could provide.
>
> Honestly I did not yet think about it too much, just current feelings.
>
Fair, fair.

- Dave

>
> Geоrge.
>
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