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diff --git a/clang-r353983/include/llvm/CodeGen/LiveIntervalUnion.h b/clang-r353983/include/llvm/CodeGen/LiveIntervalUnion.h
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+//===- LiveIntervalUnion.h - Live interval union data struct ---*- C++ -*--===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// LiveIntervalUnion is a union of live segments across multiple live virtual
+// registers. This may be used during coalescing to represent a congruence
+// class, or during register allocation to model liveness of a physical
+// register.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_LIVEINTERVALUNION_H
+#define LLVM_CODEGEN_LIVEINTERVALUNION_H
+
+#include "llvm/ADT/IntervalMap.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/CodeGen/LiveInterval.h"
+#include "llvm/CodeGen/SlotIndexes.h"
+#include <cassert>
+#include <limits>
+
+namespace llvm {
+
+class raw_ostream;
+class TargetRegisterInfo;
+
+#ifndef NDEBUG
+// forward declaration
+template <unsigned Element> class SparseBitVector;
+
+using LiveVirtRegBitSet = SparseBitVector<128>;
+#endif
+
+/// Union of live intervals that are strong candidates for coalescing into a
+/// single register (either physical or virtual depending on the context).  We
+/// expect the constituent live intervals to be disjoint, although we may
+/// eventually make exceptions to handle value-based interference.
+class LiveIntervalUnion {
+  // A set of live virtual register segments that supports fast insertion,
+  // intersection, and removal.
+  // Mapping SlotIndex intervals to virtual register numbers.
+  using LiveSegments = IntervalMap<SlotIndex, LiveInterval*>;
+
+public:
+  // SegmentIter can advance to the next segment ordered by starting position
+  // which may belong to a different live virtual register. We also must be able
+  // to reach the current segment's containing virtual register.
+  using SegmentIter = LiveSegments::iterator;
+
+  /// Const version of SegmentIter.
+  using ConstSegmentIter = LiveSegments::const_iterator;
+
+  // LiveIntervalUnions share an external allocator.
+  using Allocator = LiveSegments::Allocator;
+
+private:
+  unsigned Tag = 0;       // unique tag for current contents.
+  LiveSegments Segments;  // union of virtual reg segments
+
+public:
+  explicit LiveIntervalUnion(Allocator &a) : Segments(a) {}
+
+  // Iterate over all segments in the union of live virtual registers ordered
+  // by their starting position.
+  SegmentIter begin() { return Segments.begin(); }
+  SegmentIter end() { return Segments.end(); }
+  SegmentIter find(SlotIndex x) { return Segments.find(x); }
+  ConstSegmentIter begin() const { return Segments.begin(); }
+  ConstSegmentIter end() const { return Segments.end(); }
+  ConstSegmentIter find(SlotIndex x) const { return Segments.find(x); }
+
+  bool empty() const { return Segments.empty(); }
+  SlotIndex startIndex() const { return Segments.start(); }
+
+  // Provide public access to the underlying map to allow overlap iteration.
+  using Map = LiveSegments;
+  const Map &getMap() const { return Segments; }
+
+  /// getTag - Return an opaque tag representing the current state of the union.
+  unsigned getTag() const { return Tag; }
+
+  /// changedSince - Return true if the union change since getTag returned tag.
+  bool changedSince(unsigned tag) const { return tag != Tag; }
+
+  // Add a live virtual register to this union and merge its segments.
+  void unify(LiveInterval &VirtReg, const LiveRange &Range);
+
+  // Remove a live virtual register's segments from this union.
+  void extract(LiveInterval &VirtReg, const LiveRange &Range);
+
+  // Remove all inserted virtual registers.
+  void clear() { Segments.clear(); ++Tag; }
+
+  // Print union, using TRI to translate register names
+  void print(raw_ostream &OS, const TargetRegisterInfo *TRI) const;
+
+#ifndef NDEBUG
+  // Verify the live intervals in this union and add them to the visited set.
+  void verify(LiveVirtRegBitSet& VisitedVRegs);
+#endif
+
+  /// Query interferences between a single live virtual register and a live
+  /// interval union.
+  class Query {
+    const LiveIntervalUnion *LiveUnion = nullptr;
+    const LiveRange *LR = nullptr;
+    LiveRange::const_iterator LRI;  ///< current position in LR
+    ConstSegmentIter LiveUnionI;    ///< current position in LiveUnion
+    SmallVector<LiveInterval*,4> InterferingVRegs;
+    bool CheckedFirstInterference = false;
+    bool SeenAllInterferences = false;
+    unsigned Tag = 0;
+    unsigned UserTag = 0;
+
+    void reset(unsigned NewUserTag, const LiveRange &NewLR,
+               const LiveIntervalUnion &NewLiveUnion) {
+      LiveUnion = &NewLiveUnion;
+      LR = &NewLR;
+      InterferingVRegs.clear();
+      CheckedFirstInterference = false;
+      SeenAllInterferences = false;
+      Tag = NewLiveUnion.getTag();
+      UserTag = NewUserTag;
+    }
+
+  public:
+    Query() = default;
+    Query(const LiveRange &LR, const LiveIntervalUnion &LIU):
+      LiveUnion(&LIU), LR(&LR) {}
+    Query(const Query &) = delete;
+    Query &operator=(const Query &) = delete;
+
+    void init(unsigned NewUserTag, const LiveRange &NewLR,
+              const LiveIntervalUnion &NewLiveUnion) {
+      if (UserTag == NewUserTag && LR == &NewLR && LiveUnion == &NewLiveUnion &&
+          !NewLiveUnion.changedSince(Tag)) {
+        // Retain cached results, e.g. firstInterference.
+        return;
+      }
+      reset(NewUserTag, NewLR, NewLiveUnion);
+    }
+
+    // Does this live virtual register interfere with the union?
+    bool checkInterference() { return collectInterferingVRegs(1); }
+
+    // Count the virtual registers in this union that interfere with this
+    // query's live virtual register, up to maxInterferingRegs.
+    unsigned collectInterferingVRegs(
+        unsigned MaxInterferingRegs = std::numeric_limits<unsigned>::max());
+
+    // Was this virtual register visited during collectInterferingVRegs?
+    bool isSeenInterference(LiveInterval *VirtReg) const;
+
+    // Did collectInterferingVRegs collect all interferences?
+    bool seenAllInterferences() const { return SeenAllInterferences; }
+
+    // Vector generated by collectInterferingVRegs.
+    const SmallVectorImpl<LiveInterval*> &interferingVRegs() const {
+      return InterferingVRegs;
+    }
+  };
+
+  // Array of LiveIntervalUnions.
+  class Array {
+    unsigned Size = 0;
+    LiveIntervalUnion *LIUs = nullptr;
+
+  public:
+    Array() = default;
+    ~Array() { clear(); }
+
+    // Initialize the array to have Size entries.
+    // Reuse an existing allocation if the size matches.
+    void init(LiveIntervalUnion::Allocator&, unsigned Size);
+
+    unsigned size() const { return Size; }
+
+    void clear();
+
+    LiveIntervalUnion& operator[](unsigned idx) {
+      assert(idx <  Size && "idx out of bounds");
+      return LIUs[idx];
+    }
+
+    const LiveIntervalUnion& operator[](unsigned Idx) const {
+      assert(Idx < Size && "Idx out of bounds");
+      return LIUs[Idx];
+    }
+  };
+};
+
+} // end namespace llvm
+
+#endif // LLVM_CODEGEN_LIVEINTERVALUNION_H