[PATCH] D131287: Fix branch weight in FoldCondBranchOnValueKnownInPredecessor pass in SimplifyCFG

[Zhi Zhuang via Phabricator via llvm-commits]

LukeZhuang added a comment.

Hi Paul, thank you very much for the suggestions! I'm working on improving the code according to your comments.
For your question about JumpThreading, since I'm not an expert on this, here is my understeading:
(1) I agree that using blockfrequency(like the function that nikic suggested) is the best way to solve this issue. I was trying to use BlockFrequencyInfo at the beginning but I found this information is not maintained and no otherwhere else use this in SimplifyCFG. May I ask what do we usually do for this situation? Is that adding this in SimplifyCFG?
(2) Jumpthreading seems is doing the same thing as FoldCondBranchOnValueKnownInPredecessor in SimplifyCFG, may I ask do you know(or someone else know) why we need both of them? And jumpthreading seems is not in -O1 optimization. I guess if we can use jumpthreading, this issue would not exist at the beginning.
Any way, thank you for the comments!


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https://reviews.llvm.org/D131287