[PATCH] D125160: [InstCombine] Reassociate add sequences to reduce dependency chains

Sun May 8 19:59:49 PDT 2022

Chenbing.Zheng abandoned this revision.
Chenbing.Zheng added a comment.

In D125160#3498707 <https://reviews.llvm.org/D125160#3498707>, @spatel wrote:

> What is the motivating case for this canonicalization? This requires more justification than the usual instcombine transform because it is the inverse of what another canonicalization pass (-reassociate) would do.
>
> Note that we do have this transform in the backend with "MachineCombiner", so it should handle cases like the ones shown in the test diffs if that is profitable.

At first I wanted to solve this problem D125198 <https://reviews.llvm.org/D125198>. I think  It is friendly to instruction parallelism, so I went to do this transformation by the way. 
Do this transform in the backend with "MachineCombiner" is more reasonable.

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https://reviews.llvm.org/D125160