[PATCH] D65060: [LICM] Make Loop ICM profile aware

Mon Jul 22 12:07:30 PDT 2019

wenlei added a comment.

In D65060#1596152 <https://reviews.llvm.org/D65060#1596152>, @davidxl wrote:

> This was tried before. IIRC, the conclusion was to implement look sinking pass to undo non-profitable LICM. The loop sinking pass was in D22778 <https://reviews.llvm.org/D22778>.    Can the loop sinking pass be enhanced to handle the case here ( I have not looked in details) ?

I just looked at D22778 <https://reviews.llvm.org/D22778> briefly, but it didn't mention why we need to undo it later instead of just checking bfi during LICM - I'm curious. The loop sinking pass evidently didn't help the pathological case (a big switch inside a loop, and hundreds of switch arms got hoisted) we hit, but I didn't look into why either.

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https://reviews.llvm.org/D65060