[PATCH] D65718: [LangRef] Document forward-progress requirement

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

In D65718#1613947 <https://reviews.llvm.org/D65718#1613947>, @lebedev.ri wrote:

> I was under impression that the exact opposite was the status,
>  even if it wasn't consistently followed everywhere.


That was also my own impression as well, but @jdoerfert and @Meinersbur argued that this is the the current consensus. I would be //very// happy if this isn't the case. We should clarify this one way or another in LangRef though, to avoid future confusion on this point.

For what it's worth, actually using `llvm.sideeffect` for this purpose results in pretty catastrophic regressions right now. I think things wouldn't be quite as bad if it was only needed to control loops, but the need to also account for recursion means that `llvm.sideeffect` ends up literally everywhere. If this is indeed the way forward, we should probably add a sideeffect coalescing pass and see if that makes this at least somewhat viable.


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