[llvm] [DebugInfo][RemoveDIs] Avoid leaking trailing DPMarkers (PR #74458)

[Jeremy Morse via llvm-commits]

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@@ -1030,6 +1037,7 @@ void BasicBlock::spliceDebugInfoImpl(BasicBlock::iterator Dest, BasicBlock *Src,
     DPMarker *TrailingDPValues = getTrailingDPValues();
     if (TrailingDPValues) {
       FirstMarker->absorbDebugValues(*TrailingDPValues, true);
+      TrailingDPValues->eraseFromParent();
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jmorse wrote:

Eventually yes -- however the RemoveDIs/DDD model in-tree right now has one DPMarker allocated per instruction, and we haven't landed the plumbing required to support that (we'll get null pointer exceptions everywhere otherwise).

Over in 2f93a721eaf2aa348, which is a refactoring of the internal patch we've got, there's an "adopt" call that works very similarly to what you describe here. It might be able to automate erasing (erasal?) but still requires juggling with the trailingDPValues :(.

https://github.com/llvm/llvm-project/pull/74458