[PATCH] D66882: [DAGCombiner] Match (add X, X) as (shl X, 1) when detecting rotate.

[Amaury SECHET via Phabricator via llvm-commits]

deadalnix added a comment.

In D66882#1649078 <https://reviews.llvm.org/D66882#1649078>, @lebedev.ri wrote:

> Pattern look good to me, but i recall having disscussion in https://reviews.llvm.org/D64275#inline-576684
>  Granted, that is InstCombine, but what happens here if we create instruction but then fail to fold?


The node created this way end up added to PruningList by `WorklistInserter` are are removed when poping the next element from the worklist in `clearAddedDanglingWorklistEntries`.

@RKSimon Let me try that. This will require to refactor MatchRotate quite a bit, but it may be possible.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D66882/new/

https://reviews.llvm.org/D66882