1 files changed, 60 insertions, 4 deletions
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/GISelChangeObserver.h b/llvm/include/llvm/CodeGen/GlobalISel/GISelChangeObserver.h
index d21c73309a5..c8e8a7a5a7c 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/GISelChangeObserver.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/GISelChangeObserver.h
@@ -15,6 +15,7 @@
 #define LLVM_CODEGEN_GLOBALISEL_GISELCHANGEOBSERVER_H
 
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/CodeGen/MachineFunction.h"
 
 namespace llvm {
 class MachineInstr;
@@ -32,13 +33,13 @@ public:
   virtual ~GISelChangeObserver() {}
 
   /// An instruction is about to be erased.
-  virtual void erasingInstr(const MachineInstr &MI) = 0;
+  virtual void erasingInstr(MachineInstr &MI) = 0;
   /// An instruction was created and inserted into the function.
-  virtual void createdInstr(const MachineInstr &MI) = 0;
+  virtual void createdInstr(MachineInstr &MI) = 0;
   /// This instruction is about to be mutated in some way.
-  virtual void changingInstr(const MachineInstr &MI) = 0;
+  virtual void changingInstr(MachineInstr &MI) = 0;
   /// This instruction was mutated in some way.
-  virtual void changedInstr(const MachineInstr &MI) = 0;
+  virtual void changedInstr(MachineInstr &MI) = 0;
 
   /// All the instructions using the given register are being changed.
   /// For convenience, finishedChangingAllUsesOfReg() will report the completion
@@ -51,5 +52,60 @@ public:
 
 };
 
+/// Simple wrapper observer that takes several observers, and calls
+/// each one for each event. If there are multiple observers (say CSE,
+/// Legalizer, Combiner), it's sufficient to register this to the machine
+/// function as the delegate.
+class GISelObserverWrapper : public MachineFunction::Delegate,
+                             public GISelChangeObserver {
+  SmallVector<GISelChangeObserver *, 4> Observers;
+
+public:
+  GISelObserverWrapper() = default;
+  GISelObserverWrapper(ArrayRef<GISelChangeObserver *> Obs)
+      : Observers(Obs.begin(), Obs.end()) {}
+  // Adds an observer.
+  void addObserver(GISelChangeObserver *O) { Observers.push_back(O); }
+  // Removes an observer from the list and does nothing if observer is not
+  // present.
+  void removeObserver(GISelChangeObserver *O) {
+    auto It = std::find(Observers.begin(), Observers.end(), O);
+    if (It != Observers.end())
+      Observers.erase(It);
+  }
+  // API for Observer.
+  void erasingInstr(MachineInstr &MI) override {
+    for (auto &O : Observers)
+      O->erasingInstr(MI);
+  }
+  void createdInstr(MachineInstr &MI) override {
+    for (auto &O : Observers)
+      O->createdInstr(MI);
+  }
+  void changingInstr(MachineInstr &MI) override {
+    for (auto &O : Observers)
+      O->changingInstr(MI);
+  }
+  void changedInstr(MachineInstr &MI) override {
+    for (auto &O : Observers)
+      O->changedInstr(MI);
+  }
+  // API for MachineFunction::Delegate
+  void MF_HandleInsertion(MachineInstr &MI) override { createdInstr(MI); }
+  void MF_HandleRemoval(MachineInstr &MI) override { erasingInstr(MI); }
+};
+
+/// A simple RAII based CSEInfo installer.
+/// Use this in a scope to install a delegate to the MachineFunction and reset
+/// it at the end of the scope.
+class RAIIDelegateInstaller {
+  MachineFunction &MF;
+  MachineFunction::Delegate *Delegate;
+
+public:
+  RAIIDelegateInstaller(MachineFunction &MF, MachineFunction::Delegate *Del);
+  ~RAIIDelegateInstaller();
+};
+
 } // namespace llvm
 #endif