[RegAllocFast] Eliminate dead copies (#196056) github issue: https://github.com/llvm/llvm-project/issues/168201 This patch extends copy elimination in **RegAllocFast** to catch an additional class of redundant copies. Previously, only identity copies (where source and destination registers are the same) were marked for removal. Now, we check whether the current instruction is dead and remove it if it is. The change: - Updates the copy-elimination condition to include dead destination operands. - Improves debug output to be more generic. This reduces unnecessary instructions and can lead to slightly better codegen by eliminating dead copies earlier in the fast register allocation pass.
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