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diff --git a/contrib/llvm/lib/Transforms/Scalar/DCE.cpp b/contrib/llvm/lib/Transforms/Scalar/DCE.cpp
new file mode 100644
index 000000000000..fa4806e884c3
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+++ b/contrib/llvm/lib/Transforms/Scalar/DCE.cpp
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+//===- DCE.cpp - Code to perform dead code elimination --------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements dead inst elimination and dead code elimination.
+//
+// Dead Inst Elimination performs a single pass over the function removing
+// instructions that are obviously dead.  Dead Code Elimination is similar, but
+// it rechecks instructions that were used by removed instructions to see if
+// they are newly dead.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar/DCE.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/IR/InstIterator.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/Local.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "dce"
+
+STATISTIC(DIEEliminated, "Number of insts removed by DIE pass");
+STATISTIC(DCEEliminated, "Number of insts removed");
+
+namespace {
+  //===--------------------------------------------------------------------===//
+  // DeadInstElimination pass implementation
+  //
+  struct DeadInstElimination : public BasicBlockPass {
+    static char ID; // Pass identification, replacement for typeid
+    DeadInstElimination() : BasicBlockPass(ID) {
+      initializeDeadInstEliminationPass(*PassRegistry::getPassRegistry());
+    }
+    bool runOnBasicBlock(BasicBlock &BB) override {
+      if (skipBasicBlock(BB))
+        return false;
+      auto *TLIP = getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
+      TargetLibraryInfo *TLI = TLIP ? &TLIP->getTLI() : nullptr;
+      bool Changed = false;
+      for (BasicBlock::iterator DI = BB.begin(); DI != BB.end(); ) {
+        Instruction *Inst = &*DI++;
+        if (isInstructionTriviallyDead(Inst, TLI)) {
+          Inst->eraseFromParent();
+          Changed = true;
+          ++DIEEliminated;
+        }
+      }
+      return Changed;
+    }
+
+    void getAnalysisUsage(AnalysisUsage &AU) const override {
+      AU.setPreservesCFG();
+    }
+  };
+}
+
+char DeadInstElimination::ID = 0;
+INITIALIZE_PASS(DeadInstElimination, "die",
+                "Dead Instruction Elimination", false, false)
+
+Pass *llvm::createDeadInstEliminationPass() {
+  return new DeadInstElimination();
+}
+
+static bool DCEInstruction(Instruction *I,
+                           SmallSetVector<Instruction *, 16> &WorkList,
+                           const TargetLibraryInfo *TLI) {
+  if (isInstructionTriviallyDead(I, TLI)) {
+    // Null out all of the instruction's operands to see if any operand becomes
+    // dead as we go.
+    for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
+      Value *OpV = I->getOperand(i);
+      I->setOperand(i, nullptr);
+
+      if (!OpV->use_empty() || I == OpV)
+        continue;
+
+      // If the operand is an instruction that became dead as we nulled out the
+      // operand, and if it is 'trivially' dead, delete it in a future loop
+      // iteration.
+      if (Instruction *OpI = dyn_cast<Instruction>(OpV))
+        if (isInstructionTriviallyDead(OpI, TLI))
+          WorkList.insert(OpI);
+    }
+
+    I->eraseFromParent();
+    ++DCEEliminated;
+    return true;
+  }
+  return false;
+}
+
+static bool eliminateDeadCode(Function &F, TargetLibraryInfo *TLI) {
+  bool MadeChange = false;
+  SmallSetVector<Instruction *, 16> WorkList;
+  // Iterate over the original function, only adding insts to the worklist
+  // if they actually need to be revisited. This avoids having to pre-init
+  // the worklist with the entire function's worth of instructions.
+  for (inst_iterator FI = inst_begin(F), FE = inst_end(F); FI != FE;) {
+    Instruction *I = &*FI;
+    ++FI;
+
+    // We're visiting this instruction now, so make sure it's not in the
+    // worklist from an earlier visit.
+    if (!WorkList.count(I))
+      MadeChange |= DCEInstruction(I, WorkList, TLI);
+  }
+
+  while (!WorkList.empty()) {
+    Instruction *I = WorkList.pop_back_val();
+    MadeChange |= DCEInstruction(I, WorkList, TLI);
+  }
+  return MadeChange;
+}
+
+PreservedAnalyses DCEPass::run(Function &F, FunctionAnalysisManager &AM) {
+  if (!eliminateDeadCode(F, AM.getCachedResult<TargetLibraryAnalysis>(F)))
+    return PreservedAnalyses::all();
+
+  PreservedAnalyses PA;
+  PA.preserveSet<CFGAnalyses>();
+  return PA;
+}
+
+namespace {
+struct DCELegacyPass : public FunctionPass {
+  static char ID; // Pass identification, replacement for typeid
+  DCELegacyPass() : FunctionPass(ID) {
+    initializeDCELegacyPassPass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnFunction(Function &F) override {
+    if (skipFunction(F))
+      return false;
+
+    auto *TLIP = getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
+    TargetLibraryInfo *TLI = TLIP ? &TLIP->getTLI() : nullptr;
+
+    return eliminateDeadCode(F, TLI);
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+  }
+};
+}
+
+char DCELegacyPass::ID = 0;
+INITIALIZE_PASS(DCELegacyPass, "dce", "Dead Code Elimination", false, false)
+
+FunctionPass *llvm::createDeadCodeEliminationPass() {
+  return new DCELegacyPass();
+}