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diff --git a/gnu/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/gnu/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
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+++ b/gnu/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
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+//===- CorrelatedValuePropagation.cpp - Propagate CFG-derived info --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Correlated Value Propagation pass.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/LazyValueInfo.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/Local.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "correlated-value-propagation"
+
+STATISTIC(NumPhis,      "Number of phis propagated");
+STATISTIC(NumSelects,   "Number of selects propagated");
+STATISTIC(NumMemAccess, "Number of memory access targets propagated");
+STATISTIC(NumCmps,      "Number of comparisons propagated");
+STATISTIC(NumReturns,   "Number of return values propagated");
+STATISTIC(NumDeadCases, "Number of switch cases removed");
+
+namespace {
+  class CorrelatedValuePropagation : public FunctionPass {
+    LazyValueInfo *LVI;
+
+    bool processSelect(SelectInst *SI);
+    bool processPHI(PHINode *P);
+    bool processMemAccess(Instruction *I);
+    bool processCmp(CmpInst *C);
+    bool processSwitch(SwitchInst *SI);
+    bool processCallSite(CallSite CS);
+
+    /// Return a constant value for V usable at At and everything it
+    /// dominates.  If no such Constant can be found, return nullptr.
+    Constant *getConstantAt(Value *V, Instruction *At);
+
+  public:
+    static char ID;
+    CorrelatedValuePropagation(): FunctionPass(ID) {
+     initializeCorrelatedValuePropagationPass(*PassRegistry::getPassRegistry());
+    }
+
+    bool runOnFunction(Function &F) override;
+
+    void getAnalysisUsage(AnalysisUsage &AU) const override {
+      AU.addRequired<LazyValueInfo>();
+      AU.addPreserved<GlobalsAAWrapperPass>();
+    }
+  };
+}
+
+char CorrelatedValuePropagation::ID = 0;
+INITIALIZE_PASS_BEGIN(CorrelatedValuePropagation, "correlated-propagation",
+                "Value Propagation", false, false)
+INITIALIZE_PASS_DEPENDENCY(LazyValueInfo)
+INITIALIZE_PASS_END(CorrelatedValuePropagation, "correlated-propagation",
+                "Value Propagation", false, false)
+
+// Public interface to the Value Propagation pass
+Pass *llvm::createCorrelatedValuePropagationPass() {
+  return new CorrelatedValuePropagation();
+}
+
+bool CorrelatedValuePropagation::processSelect(SelectInst *S) {
+  if (S->getType()->isVectorTy()) return false;
+  if (isa<Constant>(S->getOperand(0))) return false;
+
+  Constant *C = LVI->getConstant(S->getOperand(0), S->getParent(), S);
+  if (!C) return false;
+
+  ConstantInt *CI = dyn_cast<ConstantInt>(C);
+  if (!CI) return false;
+
+  Value *ReplaceWith = S->getOperand(1);
+  Value *Other = S->getOperand(2);
+  if (!CI->isOne()) std::swap(ReplaceWith, Other);
+  if (ReplaceWith == S) ReplaceWith = UndefValue::get(S->getType());
+
+  S->replaceAllUsesWith(ReplaceWith);
+  S->eraseFromParent();
+
+  ++NumSelects;
+
+  return true;
+}
+
+bool CorrelatedValuePropagation::processPHI(PHINode *P) {
+  bool Changed = false;
+
+  BasicBlock *BB = P->getParent();
+  for (unsigned i = 0, e = P->getNumIncomingValues(); i < e; ++i) {
+    Value *Incoming = P->getIncomingValue(i);
+    if (isa<Constant>(Incoming)) continue;
+
+    Value *V = LVI->getConstantOnEdge(Incoming, P->getIncomingBlock(i), BB, P);
+
+    // Look if the incoming value is a select with a scalar condition for which
+    // LVI can tells us the value. In that case replace the incoming value with
+    // the appropriate value of the select. This often allows us to remove the
+    // select later.
+    if (!V) {
+      SelectInst *SI = dyn_cast<SelectInst>(Incoming);
+      if (!SI) continue;
+
+      Value *Condition = SI->getCondition();
+      if (!Condition->getType()->isVectorTy()) {
+        if (Constant *C = LVI->getConstantOnEdge(
+                Condition, P->getIncomingBlock(i), BB, P)) {
+          if (C->isOneValue()) {
+            V = SI->getTrueValue();
+          } else if (C->isZeroValue()) {
+            V = SI->getFalseValue();
+          }
+          // Once LVI learns to handle vector types, we could also add support
+          // for vector type constants that are not all zeroes or all ones.
+        }
+      }
+
+      // Look if the select has a constant but LVI tells us that the incoming
+      // value can never be that constant. In that case replace the incoming
+      // value with the other value of the select. This often allows us to
+      // remove the select later.
+      if (!V) {
+        Constant *C = dyn_cast<Constant>(SI->getFalseValue());
+        if (!C) continue;
+
+        if (LVI->getPredicateOnEdge(ICmpInst::ICMP_EQ, SI, C,
+              P->getIncomingBlock(i), BB, P) !=
+            LazyValueInfo::False)
+          continue;
+        V = SI->getTrueValue();
+      }
+
+      DEBUG(dbgs() << "CVP: Threading PHI over " << *SI << '\n');
+    }
+
+    P->setIncomingValue(i, V);
+    Changed = true;
+  }
+
+  // FIXME: Provide TLI, DT, AT to SimplifyInstruction.
+  const DataLayout &DL = BB->getModule()->getDataLayout();
+  if (Value *V = SimplifyInstruction(P, DL)) {
+    P->replaceAllUsesWith(V);
+    P->eraseFromParent();
+    Changed = true;
+  }
+
+  if (Changed)
+    ++NumPhis;
+
+  return Changed;
+}
+
+bool CorrelatedValuePropagation::processMemAccess(Instruction *I) {
+  Value *Pointer = nullptr;
+  if (LoadInst *L = dyn_cast<LoadInst>(I))
+    Pointer = L->getPointerOperand();
+  else
+    Pointer = cast<StoreInst>(I)->getPointerOperand();
+
+  if (isa<Constant>(Pointer)) return false;
+
+  Constant *C = LVI->getConstant(Pointer, I->getParent(), I);
+  if (!C) return false;
+
+  ++NumMemAccess;
+  I->replaceUsesOfWith(Pointer, C);
+  return true;
+}
+
+/// processCmp - See if LazyValueInfo's ability to exploit edge conditions,
+/// or range information is sufficient to prove this comparison.  Even for
+/// local conditions, this can sometimes prove conditions instcombine can't by
+/// exploiting range information.
+bool CorrelatedValuePropagation::processCmp(CmpInst *C) {
+  Value *Op0 = C->getOperand(0);
+  Constant *Op1 = dyn_cast<Constant>(C->getOperand(1));
+  if (!Op1) return false;
+
+  // As a policy choice, we choose not to waste compile time on anything where
+  // the comparison is testing local values.  While LVI can sometimes reason
+  // about such cases, it's not its primary purpose.  We do make sure to do
+  // the block local query for uses from terminator instructions, but that's
+  // handled in the code for each terminator.
+  auto *I = dyn_cast<Instruction>(Op0);
+  if (I && I->getParent() == C->getParent())
+    return false;
+
+  LazyValueInfo::Tristate Result =
+    LVI->getPredicateAt(C->getPredicate(), Op0, Op1, C);
+  if (Result == LazyValueInfo::Unknown) return false;
+
+  ++NumCmps;
+  if (Result == LazyValueInfo::True)
+    C->replaceAllUsesWith(ConstantInt::getTrue(C->getContext()));
+  else
+    C->replaceAllUsesWith(ConstantInt::getFalse(C->getContext()));
+  C->eraseFromParent();
+
+  return true;
+}
+
+/// processSwitch - Simplify a switch instruction by removing cases which can
+/// never fire.  If the uselessness of a case could be determined locally then
+/// constant propagation would already have figured it out.  Instead, walk the
+/// predecessors and statically evaluate cases based on information available
+/// on that edge.  Cases that cannot fire no matter what the incoming edge can
+/// safely be removed.  If a case fires on every incoming edge then the entire
+/// switch can be removed and replaced with a branch to the case destination.
+bool CorrelatedValuePropagation::processSwitch(SwitchInst *SI) {
+  Value *Cond = SI->getCondition();
+  BasicBlock *BB = SI->getParent();
+
+  // If the condition was defined in same block as the switch then LazyValueInfo
+  // currently won't say anything useful about it, though in theory it could.
+  if (isa<Instruction>(Cond) && cast<Instruction>(Cond)->getParent() == BB)
+    return false;
+
+  // If the switch is unreachable then trying to improve it is a waste of time.
+  pred_iterator PB = pred_begin(BB), PE = pred_end(BB);
+  if (PB == PE) return false;
+
+  // Analyse each switch case in turn.  This is done in reverse order so that
+  // removing a case doesn't cause trouble for the iteration.
+  bool Changed = false;
+  for (SwitchInst::CaseIt CI = SI->case_end(), CE = SI->case_begin(); CI-- != CE;
+       ) {
+    ConstantInt *Case = CI.getCaseValue();
+
+    // Check to see if the switch condition is equal to/not equal to the case
+    // value on every incoming edge, equal/not equal being the same each time.
+    LazyValueInfo::Tristate State = LazyValueInfo::Unknown;
+    for (pred_iterator PI = PB; PI != PE; ++PI) {
+      // Is the switch condition equal to the case value?
+      LazyValueInfo::Tristate Value = LVI->getPredicateOnEdge(CmpInst::ICMP_EQ,
+                                                              Cond, Case, *PI,
+                                                              BB, SI);
+      // Give up on this case if nothing is known.
+      if (Value == LazyValueInfo::Unknown) {
+        State = LazyValueInfo::Unknown;
+        break;
+      }
+
+      // If this was the first edge to be visited, record that all other edges
+      // need to give the same result.
+      if (PI == PB) {
+        State = Value;
+        continue;
+      }
+
+      // If this case is known to fire for some edges and known not to fire for
+      // others then there is nothing we can do - give up.
+      if (Value != State) {
+        State = LazyValueInfo::Unknown;
+        break;
+      }
+    }
+
+    if (State == LazyValueInfo::False) {
+      // This case never fires - remove it.
+      CI.getCaseSuccessor()->removePredecessor(BB);
+      SI->removeCase(CI); // Does not invalidate the iterator.
+
+      // The condition can be modified by removePredecessor's PHI simplification
+      // logic.
+      Cond = SI->getCondition();
+
+      ++NumDeadCases;
+      Changed = true;
+    } else if (State == LazyValueInfo::True) {
+      // This case always fires.  Arrange for the switch to be turned into an
+      // unconditional branch by replacing the switch condition with the case
+      // value.
+      SI->setCondition(Case);
+      NumDeadCases += SI->getNumCases();
+      Changed = true;
+      break;
+    }
+  }
+
+  if (Changed)
+    // If the switch has been simplified to the point where it can be replaced
+    // by a branch then do so now.
+    ConstantFoldTerminator(BB);
+
+  return Changed;
+}
+
+/// processCallSite - Infer nonnull attributes for the arguments at the
+/// specified callsite.
+bool CorrelatedValuePropagation::processCallSite(CallSite CS) {
+  SmallVector<unsigned, 4> Indices;
+  unsigned ArgNo = 0;
+
+  for (Value *V : CS.args()) {
+    PointerType *Type = dyn_cast<PointerType>(V->getType());
+
+    if (Type && !CS.paramHasAttr(ArgNo + 1, Attribute::NonNull) &&
+        LVI->getPredicateAt(ICmpInst::ICMP_EQ, V,
+                            ConstantPointerNull::get(Type),
+                            CS.getInstruction()) == LazyValueInfo::False)
+      Indices.push_back(ArgNo + 1);
+    ArgNo++;
+  }
+
+  assert(ArgNo == CS.arg_size() && "sanity check");
+
+  if (Indices.empty())
+    return false;
+
+  AttributeSet AS = CS.getAttributes();
+  LLVMContext &Ctx = CS.getInstruction()->getContext();
+  AS = AS.addAttribute(Ctx, Indices, Attribute::get(Ctx, Attribute::NonNull));
+  CS.setAttributes(AS);
+
+  return true;
+}
+
+Constant *CorrelatedValuePropagation::getConstantAt(Value *V, Instruction *At) {
+  if (Constant *C = LVI->getConstant(V, At->getParent(), At))
+    return C;
+
+  // TODO: The following really should be sunk inside LVI's core algorithm, or
+  // at least the outer shims around such.
+  auto *C = dyn_cast<CmpInst>(V);
+  if (!C) return nullptr;
+
+  Value *Op0 = C->getOperand(0);
+  Constant *Op1 = dyn_cast<Constant>(C->getOperand(1));
+  if (!Op1) return nullptr;
+  
+  LazyValueInfo::Tristate Result =
+    LVI->getPredicateAt(C->getPredicate(), Op0, Op1, At);
+  if (Result == LazyValueInfo::Unknown)
+    return nullptr;
+  
+  return (Result == LazyValueInfo::True) ?
+    ConstantInt::getTrue(C->getContext()) :
+    ConstantInt::getFalse(C->getContext());
+}
+
+bool CorrelatedValuePropagation::runOnFunction(Function &F) {
+  if (skipOptnoneFunction(F))
+    return false;
+
+  LVI = &getAnalysis<LazyValueInfo>();
+
+  bool FnChanged = false;
+
+  for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) {
+    bool BBChanged = false;
+    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); BI != BE; ) {
+      Instruction *II = &*BI++;
+      switch (II->getOpcode()) {
+      case Instruction::Select:
+        BBChanged |= processSelect(cast<SelectInst>(II));
+        break;
+      case Instruction::PHI:
+        BBChanged |= processPHI(cast<PHINode>(II));
+        break;
+      case Instruction::ICmp:
+      case Instruction::FCmp:
+        BBChanged |= processCmp(cast<CmpInst>(II));
+        break;
+      case Instruction::Load:
+      case Instruction::Store:
+        BBChanged |= processMemAccess(II);
+        break;
+      case Instruction::Call:
+      case Instruction::Invoke:
+        BBChanged |= processCallSite(CallSite(II));
+        break;
+      }
+    }
+
+    Instruction *Term = FI->getTerminator();
+    switch (Term->getOpcode()) {
+    case Instruction::Switch:
+      BBChanged |= processSwitch(cast<SwitchInst>(Term));
+      break;
+    case Instruction::Ret: {
+      auto *RI = cast<ReturnInst>(Term);
+      // Try to determine the return value if we can.  This is mainly here to
+      // simplify the writing of unit tests, but also helps to enable IPO by
+      // constant folding the return values of callees.
+      auto *RetVal = RI->getReturnValue();
+      if (!RetVal) break; // handle "ret void"
+      if (isa<Constant>(RetVal)) break; // nothing to do
+      if (auto *C = getConstantAt(RetVal, RI)) {
+        ++NumReturns;
+        RI->replaceUsesOfWith(RetVal, C);
+        BBChanged = true;        
+      }
+    }
+    };
+
+    FnChanged |= BBChanged;
+  }
+
+  return FnChanged;
+}