[PATCH] D38392: Disallow sinking of unordered atomic loads into loops

Dehao Chen via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Fri Sep 29 17:31:25 PDT 2017


danielcdh added a comment.

In https://reviews.llvm.org/D38392#885134, @reames wrote:

> In https://reviews.llvm.org/D38392#885108, @danielcdh wrote:
>
> > I see your point now. My concern is performance: if we allow hoisting of atomic load, but not allow sinking it, we may end up with bad performance as we may have too much redundant atomic loads in the preheader. Any suggestions on how to solve that?
>
>
> Not really.  I can say that we've been running performance tests for months in this configuration (LICM hoisting unordered loads, no LoopSink) without noticing any problems.  I'm not immediately concerned.


Sorry, not sure if I follow the logic, could you explain why you don't think this is a performance concern?


https://reviews.llvm.org/D38392





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