[llvm] [RegisterCoalescer] Fix reuse of instruction pointers (PR #73519)

[Matt Arsenault via llvm-commits]

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@@ -1190,7 +1203,15 @@ bool RegisterCoalescer::removePartialRedundancy(const CoalescerPair &CP,
     // If the newly created Instruction has an address of an instruction that was
     // deleted before (object recycled by the allocator) it needs to be removed from
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arsenm wrote:

I don't really trust this system of relying on deleted instruction pointers. Is there a better way to handle this?

https://github.com/llvm/llvm-project/pull/73519