[llvm-branch-commits] [llvm] release/19.x: [RemoveDIs] Fix spliceDebugInfo splice-to-end edge case (#105671, #106723) (PR #106952)

[Orlando Cazalet-Hyams via llvm-branch-commits]

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@@ -975,8 +975,16 @@ void BasicBlock::spliceDebugInfoImpl(BasicBlock::iterator Dest, BasicBlock *Src,
   if (ReadFromTail && Src->getMarker(Last)) {
     DbgMarker *FromLast = Src->getMarker(Last);
     if (LastIsEnd) {
-      Dest->adoptDbgRecords(Src, Last, true);
-      // adoptDbgRecords will release any trailers.
+      if (Dest == end()) {
+        // Abosrb the trailing markers from Src.
+        assert(FromLast == Src->getTrailingDbgRecords());
+        createMarker(Dest)->absorbDebugValues(*FromLast, true);
+        FromLast->eraseFromParent();
+        Src->deleteTrailingDbgRecords();
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OCHyams wrote:

`Src` is not null (it is dereferenced throughout function without null checks).

Here the trailing marker is deleted (eraseFromParent) and unlinked from its parent (deleteTrailingDbgRecords) - the order doesn't matter because `deleteTrailingDbgRecords` just removes the ptr from a map.

https://github.com/llvm/llvm-project/pull/106952