[llvm] [InferAddressSpaces] Safely delete duplicate dead instructions (PR #222115)

[Alex MacLean via llvm-commits]

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@@ -1661,8 +1661,12 @@ bool InferAddressSpacesImpl::rewriteWithNewAddressSpaces(
     }
   }
 
-  for (Instruction *I : DeadInstructions)
-    RecursivelyDeleteTriviallyDeadInstructions(I);
+  // Deleting one instruction may recursively delete another queued
+  // instruction. Create handles before the first deletion so overlapping
+  // entries are nulled instead of leaving dangling pointers.
+  SmallVector<WeakTrackingVH> DeadInstructionHandles(DeadInstructions.begin(),
+                                                     DeadInstructions.end());
+  RecursivelyDeleteTriviallyDeadInstructions(DeadInstructionHandles);
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AlexMaclean wrote:

Nit: can we use to_vector_of<WeakTrackingVH, 16>(DeadInstructionHandles)?

https://github.com/llvm/llvm-project/pull/222115