[llvm] [NewPM][Instrumentation] Support `MachineOptimizationRemarkEmitter` (PR #90563)

[Arthur Eubanks via llvm-commits]

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@@ -2493,6 +2551,79 @@ void PrintCrashIRInstrumentation::registerCallbacks(
       });
 }
 
+void InstrCountChangedReporter::registerCallbacks(
+    PassInstrumentationCallbacks &PIC, ModuleAnalysisManager &MAM) {
+  PIC.registerBeforeNonSkippedPassCallback([this, &MAM, Registered = false](
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aeubanks wrote:

is it possible to know ahead of time if remarks are enabled so we can avoid calling these callbacks after every pass in the common case where we don't want remarks?

https://github.com/llvm/llvm-project/pull/90563