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diff --git a/contrib/llvm-project/llvm/lib/CodeGen/GlobalISel/Combiner.cpp b/contrib/llvm-project/llvm/lib/CodeGen/GlobalISel/Combiner.cpp
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+++ b/contrib/llvm-project/llvm/lib/CodeGen/GlobalISel/Combiner.cpp
@@ -0,0 +1,147 @@
+//===-- lib/CodeGen/GlobalISel/Combiner.cpp -------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file constains common code to combine machine functions at generic
+// level.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/GlobalISel/Combiner.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/CodeGen/GlobalISel/CSEInfo.h"
+#include "llvm/CodeGen/GlobalISel/CombinerInfo.h"
+#include "llvm/CodeGen/GlobalISel/CSEMIRBuilder.h"
+#include "llvm/CodeGen/GlobalISel/GISelChangeObserver.h"
+#include "llvm/CodeGen/GlobalISel/GISelWorkList.h"
+#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
+#include "llvm/CodeGen/GlobalISel/Utils.h"
+#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "gi-combiner"
+
+using namespace llvm;
+
+namespace {
+/// This class acts as the glue the joins the CombinerHelper to the overall
+/// Combine algorithm. The CombinerHelper is intended to report the
+/// modifications it makes to the MIR to the GISelChangeObserver and the
+/// observer subclass will act on these events. In this case, instruction
+/// erasure will cancel any future visits to the erased instruction and
+/// instruction creation will schedule that instruction for a future visit.
+/// Other Combiner implementations may require more complex behaviour from
+/// their GISelChangeObserver subclass.
+class WorkListMaintainer : public GISelChangeObserver {
+  using WorkListTy = GISelWorkList<512>;
+  WorkListTy &WorkList;
+  /// The instructions that have been created but we want to report once they
+  /// have their operands. This is only maintained if debug output is requested.
+  SmallPtrSet<const MachineInstr *, 4> CreatedInstrs;
+
+public:
+  WorkListMaintainer(WorkListTy &WorkList)
+      : GISelChangeObserver(), WorkList(WorkList) {}
+  virtual ~WorkListMaintainer() {
+  }
+
+  void erasingInstr(MachineInstr &MI) override {
+    LLVM_DEBUG(dbgs() << "Erasing: " << MI << "\n");
+    WorkList.remove(&MI);
+  }
+  void createdInstr(MachineInstr &MI) override {
+    LLVM_DEBUG(dbgs() << "Creating: " << MI << "\n");
+    WorkList.insert(&MI);
+    LLVM_DEBUG(CreatedInstrs.insert(&MI));
+  }
+  void changingInstr(MachineInstr &MI) override {
+    LLVM_DEBUG(dbgs() << "Changing: " << MI << "\n");
+    WorkList.insert(&MI);
+  }
+  void changedInstr(MachineInstr &MI) override {
+    LLVM_DEBUG(dbgs() << "Changed: " << MI << "\n");
+    WorkList.insert(&MI);
+  }
+
+  void reportFullyCreatedInstrs() {
+    LLVM_DEBUG(for (const auto *MI
+                    : CreatedInstrs) {
+      dbgs() << "Created: ";
+      MI->print(dbgs());
+    });
+    LLVM_DEBUG(CreatedInstrs.clear());
+  }
+};
+}
+
+Combiner::Combiner(CombinerInfo &Info, const TargetPassConfig *TPC)
+    : CInfo(Info), TPC(TPC) {
+  (void)this->TPC; // FIXME: Remove when used.
+}
+
+bool Combiner::combineMachineInstrs(MachineFunction &MF,
+                                    GISelCSEInfo *CSEInfo) {
+  // If the ISel pipeline failed, do not bother running this pass.
+  // FIXME: Should this be here or in individual combiner passes.
+  if (MF.getProperties().hasProperty(
+          MachineFunctionProperties::Property::FailedISel))
+    return false;
+
+  Builder =
+      CSEInfo ? make_unique<CSEMIRBuilder>() : make_unique<MachineIRBuilder>();
+  MRI = &MF.getRegInfo();
+  Builder->setMF(MF);
+  if (CSEInfo)
+    Builder->setCSEInfo(CSEInfo);
+
+  LLVM_DEBUG(dbgs() << "Generic MI Combiner for: " << MF.getName() << '\n');
+
+  MachineOptimizationRemarkEmitter MORE(MF, /*MBFI=*/nullptr);
+
+  bool MFChanged = false;
+  bool Changed;
+  MachineIRBuilder &B = *Builder.get();
+
+  do {
+    // Collect all instructions. Do a post order traversal for basic blocks and
+    // insert with list bottom up, so while we pop_back_val, we'll traverse top
+    // down RPOT.
+    Changed = false;
+    GISelWorkList<512> WorkList;
+    WorkListMaintainer Observer(WorkList);
+    GISelObserverWrapper WrapperObserver(&Observer);
+    if (CSEInfo)
+      WrapperObserver.addObserver(CSEInfo);
+    RAIIDelegateInstaller DelInstall(MF, &WrapperObserver);
+    for (MachineBasicBlock *MBB : post_order(&MF)) {
+      if (MBB->empty())
+        continue;
+      for (auto MII = MBB->rbegin(), MIE = MBB->rend(); MII != MIE;) {
+        MachineInstr *CurMI = &*MII;
+        ++MII;
+        // Erase dead insts before even adding to the list.
+        if (isTriviallyDead(*CurMI, *MRI)) {
+          LLVM_DEBUG(dbgs() << *CurMI << "Is dead; erasing.\n");
+          CurMI->eraseFromParentAndMarkDBGValuesForRemoval();
+          continue;
+        }
+        WorkList.deferred_insert(CurMI);
+      }
+    }
+    WorkList.finalize();
+    // Main Loop. Process the instructions here.
+    while (!WorkList.empty()) {
+      MachineInstr *CurrInst = WorkList.pop_back_val();
+      LLVM_DEBUG(dbgs() << "\nTry combining " << *CurrInst;);
+      Changed |= CInfo.combine(WrapperObserver, *CurrInst, B);
+      Observer.reportFullyCreatedInstrs();
+    }
+    MFChanged |= Changed;
+  } while (Changed);
+
+  return MFChanged;
+}