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diff --git a/contrib/llvm-project/llvm/lib/Target/Hexagon/RDFDeadCode.h b/contrib/llvm-project/llvm/lib/Target/Hexagon/RDFDeadCode.h
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+//===--- RDFDeadCode.h ----------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// RDF-based generic dead code elimination.
+//
+// The main interface of this class are functions "collect" and "erase".
+// This allows custom processing of the function being optimized by a
+// particular consumer. The simplest way to use this class would be to
+// instantiate an object, and then simply call "collect" and "erase",
+// passing the result of "getDeadInstrs()" to it.
+// A more complex scenario would be to call "collect" first, then visit
+// all post-increment instructions to see if the address update is dead
+// or not, and if it is, convert the instruction to a non-updating form.
+// After that "erase" can be called with the set of nodes including both,
+// dead defs from the updating instructions and the nodes corresponding
+// to the dead instructions.
+
+#ifndef RDF_DEADCODE_H
+#define RDF_DEADCODE_H
+
+#include "RDFGraph.h"
+#include "RDFLiveness.h"
+#include "llvm/ADT/SetVector.h"
+
+namespace llvm {
+  class MachineRegisterInfo;
+
+namespace rdf {
+  struct DeadCodeElimination {
+    DeadCodeElimination(DataFlowGraph &dfg, MachineRegisterInfo &mri)
+      : Trace(false), DFG(dfg), MRI(mri), LV(mri, dfg) {}
+
+    bool collect();
+    bool erase(const SetVector<NodeId> &Nodes);
+    void trace(bool On) { Trace = On; }
+    bool trace() const { return Trace; }
+
+    SetVector<NodeId> getDeadNodes() { return DeadNodes; }
+    SetVector<NodeId> getDeadInstrs() { return DeadInstrs; }
+    DataFlowGraph &getDFG() { return DFG; }
+
+  private:
+    bool Trace;
+    SetVector<NodeId> LiveNodes;
+    SetVector<NodeId> DeadNodes;
+    SetVector<NodeId> DeadInstrs;
+    DataFlowGraph &DFG;
+    MachineRegisterInfo &MRI;
+    Liveness LV;
+
+    template<typename T> struct SetQueue;
+
+    bool isLiveInstr(const MachineInstr *MI) const;
+    void scanInstr(NodeAddr<InstrNode*> IA, SetQueue<NodeId> &WorkQ);
+    void processDef(NodeAddr<DefNode*> DA, SetQueue<NodeId> &WorkQ);
+    void processUse(NodeAddr<UseNode*> UA, SetQueue<NodeId> &WorkQ);
+  };
+} // namespace rdf
+} // namespace llvm
+
+#endif