[llvm] [Instrumentation] Support MachineFunction in ChangeReporter (PR #80946)

[Arthur Eubanks via llvm-commits]

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@@ -409,6 +435,10 @@ template <typename T>
 void ChangeReporter<T>::handleInvalidatedPass(StringRef PassID) {
   assert(!BeforeStack.empty() && "Unexpected empty stack encountered.");
 
+  // Prepare to process the next MIR.
+  if (PassID == FreeMachineFunctionPass::name())
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aeubanks wrote:

`InitialIR` is used to determine when to call `handleInitialIR`, which is typically used to print to the user "Initial IR: ...". I don't think we need that for MIR, except in the case where we start with MIR (mostly just tests). We can just let before/after pass handle MIR?

https://github.com/llvm/llvm-project/pull/80946