[PATCH] D100137: [JumpThreading] merge debug info when merging select+br

[Nick Desaulniers via Phabricator via llvm-commits]

nickdesaulniers added a comment.

In D100137#2678335 <https://reviews.llvm.org/D100137#2678335>, @nickdesaulniers wrote:

>> I guess it'd probably be worth fixing that code to do something to add a valid location to those function calls too
>
> Yeah, that sounds like the best long term solution to me; otherwise we'll be playing whack-a-mole with destructive transforms losing debug and results in confusing-for-developers error messages.  When splitting a critical edge, what location do we use if neither contain debug info?  If only one is missing debug info, I'd guess that `Instruction::applyMergedLocation` will pick the one existing one?

Created https://reviews.llvm.org/D100158 to followup and pursue that idea (though this issue addressed by this patch should still be fixed IMO). It looks like `llvm::SplitCriticalEdge` utilizes the debug location from the predecessors branch instruction; if it has none, oh well. So my previous question about multiple locations doesn't make much sense, as we only have 1 edge.


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https://reviews.llvm.org/D100137