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diff --git a/contrib/llvm/lib/CodeGen/RegisterCoalescer.h b/contrib/llvm/lib/CodeGen/RegisterCoalescer.h
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+//===-- RegisterCoalescer.h - Register Coalescing Interface ------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the abstract interface for register coalescers, 
+// allowing them to interact with and query register allocators.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_REGISTER_COALESCER_H
+#define LLVM_CODEGEN_REGISTER_COALESCER_H
+
+namespace llvm {
+
+  class MachineInstr;
+  class TargetRegisterInfo;
+  class TargetRegisterClass;
+  class TargetInstrInfo;
+
+  /// CoalescerPair - A helper class for register coalescers. When deciding if
+  /// two registers can be coalesced, CoalescerPair can determine if a copy
+  /// instruction would become an identity copy after coalescing.
+  class CoalescerPair {
+    const TargetInstrInfo &TII;
+    const TargetRegisterInfo &TRI;
+
+    /// DstReg - The register that will be left after coalescing. It can be a
+    /// virtual or physical register.
+    unsigned DstReg;
+
+    /// SrcReg - the virtual register that will be coalesced into dstReg.
+    unsigned SrcReg;
+
+    /// subReg_ - The subregister index of srcReg in DstReg. It is possible the
+    /// coalesce SrcReg into a subreg of the larger DstReg when DstReg is a
+    /// virtual register.
+    unsigned SubIdx;
+
+    /// Partial - True when the original copy was a partial subregister copy.
+    bool Partial;
+
+    /// CrossClass - True when both regs are virtual, and newRC is constrained.
+    bool CrossClass;
+
+    /// Flipped - True when DstReg and SrcReg are reversed from the oriignal
+    /// copy instruction.
+    bool Flipped;
+
+    /// NewRC - The register class of the coalesced register, or NULL if DstReg
+    /// is a physreg.
+    const TargetRegisterClass *NewRC;
+
+  public:
+    CoalescerPair(const TargetInstrInfo &tii, const TargetRegisterInfo &tri)
+      : TII(tii), TRI(tri), DstReg(0), SrcReg(0), SubIdx(0),
+        Partial(false), CrossClass(false), Flipped(false), NewRC(0) {}
+
+    /// setRegisters - set registers to match the copy instruction MI. Return
+    /// false if MI is not a coalescable copy instruction.
+    bool setRegisters(const MachineInstr*);
+
+    /// flip - Swap SrcReg and DstReg. Return false if swapping is impossible
+    /// because DstReg is a physical register, or SubIdx is set.
+    bool flip();
+
+    /// isCoalescable - Return true if MI is a copy instruction that will become
+    /// an identity copy after coalescing.
+    bool isCoalescable(const MachineInstr*) const;
+
+    /// isPhys - Return true if DstReg is a physical register.
+    bool isPhys() const { return !NewRC; }
+
+    /// isPartial - Return true if the original copy instruction did not copy
+    /// the full register, but was a subreg operation.
+    bool isPartial() const { return Partial; }
+
+    /// isCrossClass - Return true if DstReg is virtual and NewRC is a smaller
+    /// register class than DstReg's.
+    bool isCrossClass() const { return CrossClass; }
+
+    /// isFlipped - Return true when getSrcReg is the register being defined by
+    /// the original copy instruction.
+    bool isFlipped() const { return Flipped; }
+
+    /// getDstReg - Return the register (virtual or physical) that will remain
+    /// after coalescing.
+    unsigned getDstReg() const { return DstReg; }
+
+    /// getSrcReg - Return the virtual register that will be coalesced away.
+    unsigned getSrcReg() const { return SrcReg; }
+
+    /// getSubIdx - Return the subregister index in DstReg that SrcReg will be
+    /// coalesced into, or 0.
+    unsigned getSubIdx() const { return SubIdx; }
+
+    /// getNewRC - Return the register class of the coalesced register.
+    const TargetRegisterClass *getNewRC() const { return NewRC; }
+  };
+} // End llvm namespace
+
+#endif