[PATCH] D143229: [FunctionImporter] Don't upgrade debug info for ThinLTO compiles

Thu Feb 2 16:28:25 PST 2023

dblaikie added a subscriber: JDevlieghere.
dblaikie added a comment.

In D143229#4101253 <https://reviews.llvm.org/D143229#4101253>, @aeubanks wrote:

> In D143229#4101251 <https://reviews.llvm.org/D143229#4101251>, @mehdi_amini wrote:
>
>>> With ThinLTO, we only support cases where the input bitcode is built with the same LLVM revision
>>
>> I am pretty sure ThinLTO was designed without this restriction, where is it coming from?
>
> Hmm I thought I remembered this being true, I may be wrong though. Hopefully others can comment.
> If my assumption is wrong, I can make this into a flag instead.

Yeah, my understanding's with @mehdi_amini too - that ThinLTO should be/is currently compatible with archived bitcode (Apple folks would be the ones most likely to speak to that, perhaps @tejohnson knows who's best to rope in on their side these days), it's just that our (Google) internal use doesn't need this flexibility and is paying a penalty for it. The cost of running the IR verifier for debug info might interest @aprantl and @JDevlieghere in case they've got ideas about other ways to address this or might just be interested in knowing it's hot and might be worth improvements, even if Google still ends up turning it off entirely.

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  https://reviews.llvm.org/D143229/new/

https://reviews.llvm.org/D143229