[PATCH] D80274: [MachineVerifier] Handle the PHI node for verifyLiveVariables()

Matt Arsenault via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Jul 22 10:29:56 PDT 2020


arsenm added a comment.

In D80274#2164158 <https://reviews.llvm.org/D80274#2164158>, @bjope wrote:

> I'm a bit curious about the overall plan here. Some years ago the plan was to remove LiveVariables, and use LiveIntervals instead. And afaik PHIElimination was updated to support both LiveVariables and LiveIntervals, while TwoAddressInstructionPass only got partially updated. So for several years there have been a technical debt here, considering that the passes involved in de-SSA to some degree are supporting both LiveVaribels and LiveIntervals, while only LiveVariables is used in practise (and the support for LiveIntervals may have rotten since it is poorly tested).
>
> Considering that work now is being done to tidy up the LiveVariables support (or at least the verification of it), maybe we should consider dropping LiveIntervals support in the de-SSA phase completely. Or maybe we should spend time on finalizing the phase-out of LiveVariables instead. Is this perhaps something that you have been thinking about?


The idea is to remove kill flags and LiveVariables


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