LGTM. Thank you for revising the patch!

It looks like the testcase can be reduced to the following. You can check for no jump threading occurring:

Incorporated feedback from efriedma to use llvm::is_contained instead
of llvm::find.

Sorry, the infinite recursion seems to come from EvaluateOnPredecessorEdge, a function that I recently added to support jump threading across two basic blocks. EvaluateOnPredecessorEdge does not have a guard against infinite recursion while its close cousin ComputeValueKnownInPredecessors does.

Hi junparser, your main change in JumpThreading.cpp looks good. Now, could you explain your change in removed-use.ll? To be honest, I haven't understood the original intent of the testcase. Thanks!

Hi @maxim-kuvyrkov, would you mind filing two separate issues -- the size and performance -- preferably with preprocessed source code? Thanks!

LGTM.

Thank you for catching this! I meant to handle PredBB ending with a conditional branch only, but I wasn't aware that PredBB could end with an unconditional branch if its address is taken.

I've fixed the confusing debug message that Wei has pointed out.

I've fixed several bugs. PTAL Thanks!

This patch is work-in-progress, but I am uploading it now so I can
share it with wider audience. I am still working on fixing loose
ends.

I am re-opening this so that I can check in a revised version.

I echo what other have said.

PTAL Thanks!

I've further simplied thread-two-bbs3.ll, the testcase for Windows,
and made it a little more robust with:

I'm abandoning this change. We'll discuss the revision in https://reviews.llvm.org/D70247 instead.

PTAL Thanks!

I'm reopening this so that I can upload a revision containing a fix for Windows build.

I've reverted the change for now. I'll take a look at the failure on Windows.

Please take a look. Thanks!

Updated the patch, incorporating feedback from Wei.

https://reviews.llvm.org/D71733 supersedes this patch.

I've updated the patch so that we commit to jump threading across two
basic blocks once we are done with analysis. That is, we don't
transform the IR partially only to see jump threading proper failing.

Self-LGTM as this is a very simple NFC.

Updated to incorporate the feedback.

I've decided to scale back. I'm now simply factoring out code to
clone instructions. I thought about capturing more functionality into
CloneBasicBlock as you suggeted, but then the function would lose
generality I need for my upcoming patch.

I've incorporated the feedback from wmi.