[PATCH] D59936: SimplifyCFG SinkCommonCodeFromPredecessors: Also sink function calls without used results (PR41259)

Wed Apr 3 01:29:44 PDT 2019

hans added a comment.

In D59936#1452733 <https://reviews.llvm.org/D59936#1452733>, @uabelho wrote:

> When looking at some code changes for my out-of-tree target with this commit I noticed a change that I thought I'd ask if you think
>  is good or not.
>
> With this change we now seem to sink e.g. calls to @llvm.lifetime.end? It returns void, and thus has 0 uses, and as far as I understand
>  such calls were not sinked before? Is this on purpose and is that good? In general I guess it's good to do lifetime.end at soon as possible?
>
> (And I suppose there are also a whole bunch of other intrinsics that also return void that can be sinked now, I've no idea if that
>  can cause problems somewhere?)

It's not on purpose in the sense that I was targeting the lifetime intrinsics, but it's showing my change working as intended.

For the lifetime intrinsics, I don't think this really matters. As you say, it's good to do lifetime.end as soon as possible, so sinking them in general doesn't make sense, but I also don't think this matters much here because they can't be sunk very far, i.e. I don't see how this sinking could actually extend the lifetime.

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  https://reviews.llvm.org/D59936/new/

https://reviews.llvm.org/D59936