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diff --git a/contrib/llvm-project/llvm/include/llvm/CodeGen/LiveIntervalCalc.h b/contrib/llvm-project/llvm/include/llvm/CodeGen/LiveIntervalCalc.h
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+//===- LiveIntervalCalc.h - Calculate live intervals -----------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// The LiveIntervalCalc class is an extension of LiveRangeCalc targeted to the
+// computation and modification of the LiveInterval variants of LiveRanges.
+// LiveIntervals are meant to track liveness of registers and stack slots and
+// LiveIntervalCalc adds to LiveRangeCalc all the machinery requied to
+// construct the liveness of virtual registers tracked by a LiveInterval.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_CODEGEN_LIVEINTERVALCALC_H
+#define LLVM_LIB_CODEGEN_LIVEINTERVALCALC_H
+
+#include "llvm/CodeGen/LiveRangeCalc.h"
+
+namespace llvm {
+
+template <class NodeT> class DomTreeNodeBase;
+
+using MachineDomTreeNode = DomTreeNodeBase<MachineBasicBlock>;
+
+class LiveIntervalCalc : public LiveRangeCalc {
+  /// Extend the live range of @p LR to reach all uses of Reg.
+  ///
+  /// If @p LR is a main range, or if @p LI is null, then all uses must be
+  /// jointly dominated by the definitions from @p LR. If @p LR is a subrange
+  /// of the live interval @p LI, corresponding to lane mask @p LaneMask,
+  /// all uses must be jointly dominated by the definitions from @p LR
+  /// together with definitions of other lanes where @p LR becomes undefined
+  /// (via <def,read-undef> operands).
+  /// If @p LR is a main range, the @p LaneMask should be set to ~0, i.e.
+  /// LaneBitmask::getAll().
+  void extendToUses(LiveRange &LR, Register Reg, LaneBitmask LaneMask,
+                    LiveInterval *LI = nullptr);
+
+public:
+  LiveIntervalCalc() = default;
+
+  /// createDeadDefs - Create a dead def in LI for every def operand of Reg.
+  /// Each instruction defining Reg gets a new VNInfo with a corresponding
+  /// minimal live range.
+  void createDeadDefs(LiveRange &LR, Register Reg);
+
+  /// Extend the live range of @p LR to reach all uses of Reg.
+  ///
+  /// All uses must be jointly dominated by existing liveness.  PHI-defs are
+  /// inserted as needed to preserve SSA form.
+  void extendToUses(LiveRange &LR, MCRegister PhysReg) {
+    extendToUses(LR, PhysReg, LaneBitmask::getAll());
+  }
+
+  /// Calculates liveness for the register specified in live interval @p LI.
+  /// Creates subregister live ranges as needed if subreg liveness tracking is
+  /// enabled.
+  void calculate(LiveInterval &LI, bool TrackSubRegs);
+
+  /// For live interval \p LI with correct SubRanges construct matching
+  /// information for the main live range. Expects the main live range to not
+  /// have any segments or value numbers.
+  void constructMainRangeFromSubranges(LiveInterval &LI);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_LIB_CODEGEN_LIVEINTERVALCALC_H