[llvm] [CodeGen] Port FreeMachineFunction to new pass manager (PR #79421)

[via llvm-commits]

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@@ -125,8 +125,8 @@ MACHINE_FUNCTION_ANALYSIS("pass-instrumentation", PassInstrumentationAnalysis,
 #ifndef MACHINE_FUNCTION_PASS
 #define MACHINE_FUNCTION_PASS(NAME, PASS_NAME, CONSTRUCTOR)
 #endif
+MACHINE_FUNCTION_PASS("free-machine-function", FreeMachineFunctionPass, ())
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paperchalice wrote:

In theory we should never run this pass manually, `MachineFunctionPassManager` will always create a machine function (by getOrCreateMachineFunction). Or we shouldn't expose this pass , like `BitcodeWriterPass`.

https://github.com/llvm/llvm-project/pull/79421