[llvm-mca] Refactor event listeners to make the backend agnostic to event types.

Summary: This is a first step towards making the pipeline configurable.

Subscribers: llvm-commits, andreadb

Differential Revision: https://reviews.llvm.org/D44309

llvm-svn: 327389
diff --git a/llvm/tools/llvm-mca/ResourcePressureView.h b/llvm/tools/llvm-mca/ResourcePressureView.h
index 105aa40..1b577a2 100644
--- a/llvm/tools/llvm-mca/ResourcePressureView.h
+++ b/llvm/tools/llvm-mca/ResourcePressureView.h
@@ -96,9 +96,7 @@
     initialize();
   }
 
-  void onInstructionIssued(
-      unsigned Index,
-      const llvm::ArrayRef<std::pair<ResourceRef, unsigned>> &Used) override;
+  void onInstructionEvent(const HWInstructionEvent &Event) override;
 
   void printView(llvm::raw_ostream &OS) const override {
     unsigned Executions = Source.getNumIterations();