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

[Zhi Zhuang via Phabricator via llvm-commits]

LukeZhuang added a comment.

In D131287#3710144 <https://reviews.llvm.org/D131287#3710144>, @nikic wrote:

> This is a jump threading optimization -- is it possible to reuse the branch weight adjustment code from the JumpThreading pass? The updateBlockFreqAndEdgeWeight() method looks relevant.

Hi Nikic, thanks for the comments! Actually I have two questions about this:

1. I just looked at the code, JumpThreading pass seems did the same thing as FoldCondBranchOnValueKnownInPredecessor in SimplifyCFG. May I ask why we need both of them originally? Or is this just my misunderstanding
2. I previously also thinking of using BlockFrequencyInfo but I found it's not used and maintained in SimplifyCFG pass. Is that means we need to add it?


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https://reviews.llvm.org/D131287