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diff --git a/include/llvm/CodeGen/LiveStacks.h b/include/llvm/CodeGen/LiveStacks.h
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+++ b/include/llvm/CodeGen/LiveStacks.h
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+//===- LiveStacks.h - Live Stack Slot Analysis ------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the live stack slot analysis pass. It is analogous to
+// live interval analysis except it's analyzing liveness of stack slots rather
+// than registers.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_LIVESTACKS_H
+#define LLVM_CODEGEN_LIVESTACKS_H
+
+#include "llvm/CodeGen/LiveInterval.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/Pass.h"
+#include <cassert>
+#include <map>
+#include <unordered_map>
+
+namespace llvm {
+
+class TargetRegisterClass;
+class TargetRegisterInfo;
+
+class LiveStacks : public MachineFunctionPass {
+  const TargetRegisterInfo *TRI;
+
+  /// Special pool allocator for VNInfo's (LiveInterval val#).
+  ///
+  VNInfo::Allocator VNInfoAllocator;
+
+  /// S2IMap - Stack slot indices to live interval mapping.
+  using SS2IntervalMap = std::unordered_map<int, LiveInterval>;
+  SS2IntervalMap S2IMap;
+
+  /// S2RCMap - Stack slot indices to register class mapping.
+  std::map<int, const TargetRegisterClass *> S2RCMap;
+
+public:
+  static char ID; // Pass identification, replacement for typeid
+
+  LiveStacks() : MachineFunctionPass(ID) {
+    initializeLiveStacksPass(*PassRegistry::getPassRegistry());
+  }
+
+  using iterator = SS2IntervalMap::iterator;
+  using const_iterator = SS2IntervalMap::const_iterator;
+
+  const_iterator begin() const { return S2IMap.begin(); }
+  const_iterator end() const { return S2IMap.end(); }
+  iterator begin() { return S2IMap.begin(); }
+  iterator end() { return S2IMap.end(); }
+
+  unsigned getNumIntervals() const { return (unsigned)S2IMap.size(); }
+
+  LiveInterval &getOrCreateInterval(int Slot, const TargetRegisterClass *RC);
+
+  LiveInterval &getInterval(int Slot) {
+    assert(Slot >= 0 && "Spill slot indice must be >= 0");
+    SS2IntervalMap::iterator I = S2IMap.find(Slot);
+    assert(I != S2IMap.end() && "Interval does not exist for stack slot");
+    return I->second;
+  }
+
+  const LiveInterval &getInterval(int Slot) const {
+    assert(Slot >= 0 && "Spill slot indice must be >= 0");
+    SS2IntervalMap::const_iterator I = S2IMap.find(Slot);
+    assert(I != S2IMap.end() && "Interval does not exist for stack slot");
+    return I->second;
+  }
+
+  bool hasInterval(int Slot) const { return S2IMap.count(Slot); }
+
+  const TargetRegisterClass *getIntervalRegClass(int Slot) const {
+    assert(Slot >= 0 && "Spill slot indice must be >= 0");
+    std::map<int, const TargetRegisterClass *>::const_iterator I =
+        S2RCMap.find(Slot);
+    assert(I != S2RCMap.end() &&
+           "Register class info does not exist for stack slot");
+    return I->second;
+  }
+
+  VNInfo::Allocator &getVNInfoAllocator() { return VNInfoAllocator; }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+  void releaseMemory() override;
+
+  /// runOnMachineFunction - pass entry point
+  bool runOnMachineFunction(MachineFunction &) override;
+
+  /// print - Implement the dump method.
+  void print(raw_ostream &O, const Module * = nullptr) const override;
+};
+
+} // end namespace llvm
+
+#endif