[PATCH] D124315: lld: Bundle compact_unwind_encoding.h in lld to fix stand-alone builds

Fri Apr 22 18:48:20 PDT 2022

smeenai added a comment.

In D124315#3469458 <https://reviews.llvm.org/D124315#3469458>, @tstellar wrote:

> In D124315#3469449 <https://reviews.llvm.org/D124315#3469449>, @smeenai wrote:
>
>> To be clear, this is to support a build scenario where you only have the source tree under `lld` available?
>
> Yes, that's correct.

Ah, I'd missed that part of the definition in https://discourse.llvm.org/t/rfc-stand-alone-build-support/61291. Thanks for confirming.

The duplication here is really unfortunate, especially cos the burden of keeping the copied header up-to-date will fall on non-standalone build users. On the other hand, this header hasn't seen actual (non-license) update since 2016, so I imagine it'll remain pretty stable going forward.

An alternative would have been to move the header into LLVM (I think BinaryFormat would be a reasonable place for it), and then have libunwind and LLD both use it from there. It's still unclear if libunwind can use LLVM headers though; I don't see any existing usage, and the demangler is still duplicated between libc++abi and LLVM, for example.

All things considered, I'm fine with this; I'll give others some time to chime in as well though.

Repository:
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  https://reviews.llvm.org/D124315/new/

https://reviews.llvm.org/D124315