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diff --git a/llvm/lib/CodeGen/VirtRegMap.h b/llvm/lib/CodeGen/VirtRegMap.h
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+++ b/llvm/lib/CodeGen/VirtRegMap.h
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+//===-- llvm/CodeGen/VirtRegMap.h - Virtual Register Map -*- C++ -*--------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a virtual register map. This maps virtual
+// registers to physical registers and virtual registers to stack
+// slots. It is created and updated by a register allocator and then
+// used by a machine code rewriter that adds spill code and rewrites
+// virtual into physical register references.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_VIRTREGMAP_H
+#define LLVM_CODEGEN_VIRTREGMAP_H
+
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/SSARegMap.h"
+#include <climits>
+
+namespace llvm {
+
+    class VirtRegMap {
+    public:
+        typedef std::vector<unsigned> Virt2PhysMap;
+        typedef std::vector<int> Virt2StackSlotMap;
+ 
+        enum {
+            NO_PHYS_REG   = 0,
+            NO_STACK_SLOT = INT_MAX
+        };
+
+    private:
+        MachineFunction* mf_;
+        Virt2PhysMap v2pMap_;
+        Virt2StackSlotMap v2ssMap_;
+
+        // do not implement
+        VirtRegMap(const VirtRegMap& rhs);
+        const VirtRegMap& operator=(const VirtRegMap& rhs);
+
+        static unsigned toIndex(unsigned virtReg) {
+            return virtReg - MRegisterInfo::FirstVirtualRegister;
+        }
+        static unsigned fromIndex(unsigned index) {
+            return index + MRegisterInfo::FirstVirtualRegister;
+        }
+
+    public:
+        VirtRegMap(MachineFunction& mf)
+            : mf_(&mf),
+              v2pMap_(mf.getSSARegMap()->getNumVirtualRegs(), NO_PHYS_REG),
+              v2ssMap_(mf.getSSARegMap()->getNumVirtualRegs(), NO_STACK_SLOT) {
+        }
+
+        unsigned getPhys4Virt(unsigned virtReg) const {
+            assert(MRegisterInfo::isVirtualRegister(virtReg));
+            return v2pMap_[toIndex(virtReg)];
+        }
+
+        void assignVirt2Phys(unsigned virtReg, unsigned physReg) {
+            assert(MRegisterInfo::isVirtualRegister(virtReg) &&
+                   MRegisterInfo::isPhysicalRegister(physReg));
+            assert(v2pMap_[toIndex(virtReg)] == NO_PHYS_REG &&
+                   "attempt to assign physical register to already mapped "
+                   "virtual register");
+            v2pMap_[toIndex(virtReg)] = physReg;
+        }
+
+        void clearVirtReg(unsigned virtReg) {
+            assert(MRegisterInfo::isVirtualRegister(virtReg));
+            assert(v2pMap_[toIndex(virtReg)] != NO_PHYS_REG &&
+                   "attempt to clear a not assigned virtual register");
+            v2pMap_[toIndex(virtReg)] = NO_PHYS_REG;
+        }
+
+        int getStackSlot4Virt(unsigned virtReg) const {
+            assert(MRegisterInfo::isVirtualRegister(virtReg));
+            return v2ssMap_[toIndex(virtReg)];
+        }
+
+        int assignVirt2StackSlot(unsigned virtReg);
+
+        friend std::ostream& operator<<(std::ostream& os, const VirtRegMap& li);
+    };
+
+    std::ostream& operator<<(std::ostream& os, const VirtRegMap& li);
+
+} // End llvm namespace
+
+#endif