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Mark MergedLoadStoreMotion as not preserving MemDep results
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Authored by dotdash on Feb 12 2018, 3:04 AM.

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Summary

MemDep caches results that signify that a dependence is non-local, and
there is currently no way to invalidate such cache entries.
Unfortunately, when MLSM sinks a store that can result in a non-local
dependence becoming a local one, and then MemDep gives wrong answers.
The easiest way out here is to just say that MLSM does indeed not
preserve MemDep results.

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rL LLVM

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dotdash created this revision.Feb 12 2018, 3:04 AM

I think this Is in line with what Gerolf had in mind, but I'll let him sign off this one.

Hi Gerolf,

I just wanted to check if you could have a look at this patch.

Thanks!

Yes, this LGTM. I could not find a way to perform updates properly in the example. If recomputing the dependencies results in a compile-time issue we will have to dig deeper into MemDep.

Thanks for your fix + patience!

Cheers
Gerolf

This revision was not accepted when it landed; it landed in state Needs Review.Feb 23 2018, 2:44 AM
This revision was automatically updated to reflect the committed changes.