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diff --git a/llvm/lib/Analysis/LoopUnrollAnalyzer.cpp b/llvm/lib/Analysis/LoopUnrollAnalyzer.cpp
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+++ b/llvm/lib/Analysis/LoopUnrollAnalyzer.cpp
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+//===- LoopUnrollAnalyzer.cpp - Unrolling Effect Estimation -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements UnrolledInstAnalyzer class. It's used for predicting
+// potential effects that loop unrolling might have, such as enabling constant
+// propagation and other optimizations.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/LoopUnrollAnalyzer.h"
+#include "llvm/IR/Dominators.h"
+
+using namespace llvm;
+
+/// \brief Try to simplify instruction \param I using its SCEV expression.
+///
+/// The idea is that some AddRec expressions become constants, which then
+/// could trigger folding of other instructions. However, that only happens
+/// for expressions whose start value is also constant, which isn't always the
+/// case. In another common and important case the start value is just some
+/// address (i.e. SCEVUnknown) - in this case we compute the offset and save
+/// it along with the base address instead.
+bool UnrolledInstAnalyzer::simplifyInstWithSCEV(Instruction *I) {
+  if (!SE.isSCEVable(I->getType()))
+    return false;
+
+  const SCEV *S = SE.getSCEV(I);
+  if (auto *SC = dyn_cast<SCEVConstant>(S)) {
+    SimplifiedValues[I] = SC->getValue();
+    return true;
+  }
+
+  auto *AR = dyn_cast<SCEVAddRecExpr>(S);
+  if (!AR)
+    return false;
+
+  const SCEV *ValueAtIteration = AR->evaluateAtIteration(IterationNumber, SE);
+  // Check if the AddRec expression becomes a constant.
+  if (auto *SC = dyn_cast<SCEVConstant>(ValueAtIteration)) {
+    SimplifiedValues[I] = SC->getValue();
+    return true;
+  }
+
+  // Check if the offset from the base address becomes a constant.
+  auto *Base = dyn_cast<SCEVUnknown>(SE.getPointerBase(S));
+  if (!Base)
+    return false;
+  auto *Offset =
+      dyn_cast<SCEVConstant>(SE.getMinusSCEV(ValueAtIteration, Base));
+  if (!Offset)
+    return false;
+  SimplifiedAddress Address;
+  Address.Base = Base->getValue();
+  Address.Offset = Offset->getValue();
+  SimplifiedAddresses[I] = Address;
+  return true;
+}
+
+/// Try to simplify binary operator I.
+///
+/// TODO: Probably it's worth to hoist the code for estimating the
+/// simplifications effects to a separate class, since we have a very similar
+/// code in InlineCost already.
+bool UnrolledInstAnalyzer::visitBinaryOperator(BinaryOperator &I) {
+  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+  if (!isa<Constant>(LHS))
+    if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
+      LHS = SimpleLHS;
+  if (!isa<Constant>(RHS))
+    if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
+      RHS = SimpleRHS;
+
+  Value *SimpleV = nullptr;
+  const DataLayout &DL = I.getModule()->getDataLayout();
+  if (auto FI = dyn_cast<FPMathOperator>(&I))
+    SimpleV =
+        SimplifyFPBinOp(I.getOpcode(), LHS, RHS, FI->getFastMathFlags(), DL);
+  else
+    SimpleV = SimplifyBinOp(I.getOpcode(), LHS, RHS, DL);
+
+  if (Constant *C = dyn_cast_or_null<Constant>(SimpleV))
+    SimplifiedValues[&I] = C;
+
+  if (SimpleV)
+    return true;
+  return Base::visitBinaryOperator(I);
+}
+
+/// Try to fold load I.
+bool UnrolledInstAnalyzer::visitLoad(LoadInst &I) {
+  Value *AddrOp = I.getPointerOperand();
+
+  auto AddressIt = SimplifiedAddresses.find(AddrOp);
+  if (AddressIt == SimplifiedAddresses.end())
+    return false;
+  ConstantInt *SimplifiedAddrOp = AddressIt->second.Offset;
+
+  auto *GV = dyn_cast<GlobalVariable>(AddressIt->second.Base);
+  // We're only interested in loads that can be completely folded to a
+  // constant.
+  if (!GV || !GV->hasDefinitiveInitializer() || !GV->isConstant())
+    return false;
+
+  ConstantDataSequential *CDS =
+      dyn_cast<ConstantDataSequential>(GV->getInitializer());
+  if (!CDS)
+    return false;
+
+  // We might have a vector load from an array. FIXME: for now we just bail
+  // out in this case, but we should be able to resolve and simplify such
+  // loads.
+  if(!CDS->isElementTypeCompatible(I.getType()))
+    return false;
+
+  int ElemSize = CDS->getElementType()->getPrimitiveSizeInBits() / 8U;
+  assert(SimplifiedAddrOp->getValue().getActiveBits() < 64 &&
+         "Unexpectedly large index value.");
+  int64_t Index = SimplifiedAddrOp->getSExtValue() / ElemSize;
+  if (Index >= CDS->getNumElements()) {
+    // FIXME: For now we conservatively ignore out of bound accesses, but
+    // we're allowed to perform the optimization in this case.
+    return false;
+  }
+
+  Constant *CV = CDS->getElementAsConstant(Index);
+  assert(CV && "Constant expected.");
+  SimplifiedValues[&I] = CV;
+
+  return true;
+}
+
+/// Try to simplify cast instruction.
+bool UnrolledInstAnalyzer::visitCastInst(CastInst &I) {
+  // Propagate constants through casts.
+  Constant *COp = dyn_cast<Constant>(I.getOperand(0));
+  if (!COp)
+    COp = SimplifiedValues.lookup(I.getOperand(0));
+  if (COp)
+    if (Constant *C =
+            ConstantExpr::getCast(I.getOpcode(), COp, I.getType())) {
+      SimplifiedValues[&I] = C;
+      return true;
+    }
+
+  return Base::visitCastInst(I);
+}
+
+/// Try to simplify cmp instruction.
+bool UnrolledInstAnalyzer::visitCmpInst(CmpInst &I) {
+  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+
+  // First try to handle simplified comparisons.
+  if (!isa<Constant>(LHS))
+    if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
+      LHS = SimpleLHS;
+  if (!isa<Constant>(RHS))
+    if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
+      RHS = SimpleRHS;
+
+  if (!isa<Constant>(LHS) && !isa<Constant>(RHS)) {
+    auto SimplifiedLHS = SimplifiedAddresses.find(LHS);
+    if (SimplifiedLHS != SimplifiedAddresses.end()) {
+      auto SimplifiedRHS = SimplifiedAddresses.find(RHS);
+      if (SimplifiedRHS != SimplifiedAddresses.end()) {
+        SimplifiedAddress &LHSAddr = SimplifiedLHS->second;
+        SimplifiedAddress &RHSAddr = SimplifiedRHS->second;
+        if (LHSAddr.Base == RHSAddr.Base) {
+          LHS = LHSAddr.Offset;
+          RHS = RHSAddr.Offset;
+        }
+      }
+    }
+  }
+
+  if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
+    if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
+      if (Constant *C = ConstantExpr::getCompare(I.getPredicate(), CLHS, CRHS)) {
+        SimplifiedValues[&I] = C;
+        return true;
+      }
+    }
+  }
+
+  return Base::visitCmpInst(I);
+}