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diff --git a/lib/Analysis/ScopedNoAliasAA.cpp b/lib/Analysis/ScopedNoAliasAA.cpp
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+//===- ScopedNoAliasAA.cpp - Scoped No-Alias Alias Analysis ---------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the ScopedNoAlias alias-analysis pass, which implements
+// metadata-based scoped no-alias support.
+//
+// Alias-analysis scopes are defined by an id (which can be a string or some
+// other metadata node), a domain node, and an optional descriptive string.
+// A domain is defined by an id (which can be a string or some other metadata
+// node), and an optional descriptive string.
+//
+// !dom0 =   metadata !{ metadata !"domain of foo()" }
+// !scope1 = metadata !{ metadata !scope1, metadata !dom0, metadata !"scope 1" }
+// !scope2 = metadata !{ metadata !scope2, metadata !dom0, metadata !"scope 2" }
+//
+// Loads and stores can be tagged with an alias-analysis scope, and also, with
+// a noalias tag for a specific scope:
+//
+// ... = load %ptr1, !alias.scope !{ !scope1 }
+// ... = load %ptr2, !alias.scope !{ !scope1, !scope2 }, !noalias !{ !scope1 }
+//
+// When evaluating an aliasing query, if one of the instructions is associated
+// has a set of noalias scopes in some domain that is superset of the alias
+// scopes in that domain of some other instruction, then the two memory
+// accesses are assumed not to alias.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/Analysis/Passes.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/CommandLine.h"
+using namespace llvm;
+
+// A handy option for disabling scoped no-alias functionality. The same effect
+// can also be achieved by stripping the associated metadata tags from IR, but
+// this option is sometimes more convenient.
+static cl::opt<bool>
+EnableScopedNoAlias("enable-scoped-noalias", cl::init(true));
+
+namespace {
+/// AliasScopeNode - This is a simple wrapper around an MDNode which provides
+/// a higher-level interface by hiding the details of how alias analysis
+/// information is encoded in its operands.
+class AliasScopeNode {
+  const MDNode *Node;
+
+public:
+  AliasScopeNode() : Node(0) {}
+  explicit AliasScopeNode(const MDNode *N) : Node(N) {}
+
+  /// getNode - Get the MDNode for this AliasScopeNode.
+  const MDNode *getNode() const { return Node; }
+
+  /// getDomain - Get the MDNode for this AliasScopeNode's domain.
+  const MDNode *getDomain() const {
+    if (Node->getNumOperands() < 2)
+      return nullptr;
+    return dyn_cast_or_null<MDNode>(Node->getOperand(1));
+  }
+};
+
+/// ScopedNoAliasAA - This is a simple alias analysis
+/// implementation that uses scoped-noalias metadata to answer queries.
+class ScopedNoAliasAA : public ImmutablePass, public AliasAnalysis {
+public:
+  static char ID; // Class identification, replacement for typeinfo
+  ScopedNoAliasAA() : ImmutablePass(ID) {
+    initializeScopedNoAliasAAPass(*PassRegistry::getPassRegistry());
+  }
+
+  void initializePass() override { InitializeAliasAnalysis(this); }
+
+  /// getAdjustedAnalysisPointer - This method is used when a pass implements
+  /// an analysis interface through multiple inheritance.  If needed, it
+  /// should override this to adjust the this pointer as needed for the
+  /// specified pass info.
+  void *getAdjustedAnalysisPointer(const void *PI) override {
+    if (PI == &AliasAnalysis::ID)
+      return (AliasAnalysis*)this;
+    return this;
+  }
+
+protected:
+  bool mayAliasInScopes(const MDNode *Scopes, const MDNode *NoAlias) const;
+  void collectMDInDomain(const MDNode *List, const MDNode *Domain,
+                         SmallPtrSetImpl<const MDNode *> &Nodes) const;
+
+private:
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+  AliasResult alias(const Location &LocA, const Location &LocB) override;
+  bool pointsToConstantMemory(const Location &Loc, bool OrLocal) override;
+  ModRefBehavior getModRefBehavior(ImmutableCallSite CS) override;
+  ModRefBehavior getModRefBehavior(const Function *F) override;
+  ModRefResult getModRefInfo(ImmutableCallSite CS,
+                             const Location &Loc) override;
+  ModRefResult getModRefInfo(ImmutableCallSite CS1,
+                             ImmutableCallSite CS2) override;
+};
+}  // End of anonymous namespace
+
+// Register this pass...
+char ScopedNoAliasAA::ID = 0;
+INITIALIZE_AG_PASS(ScopedNoAliasAA, AliasAnalysis, "scoped-noalias",
+                   "Scoped NoAlias Alias Analysis", false, true, false)
+
+ImmutablePass *llvm::createScopedNoAliasAAPass() {
+  return new ScopedNoAliasAA();
+}
+
+void
+ScopedNoAliasAA::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesAll();
+  AliasAnalysis::getAnalysisUsage(AU);
+}
+
+void
+ScopedNoAliasAA::collectMDInDomain(const MDNode *List, const MDNode *Domain,
+                   SmallPtrSetImpl<const MDNode *> &Nodes) const {
+  for (unsigned i = 0, ie = List->getNumOperands(); i != ie; ++i)
+    if (const MDNode *MD = dyn_cast<MDNode>(List->getOperand(i)))
+      if (AliasScopeNode(MD).getDomain() == Domain)
+        Nodes.insert(MD);
+}
+
+bool
+ScopedNoAliasAA::mayAliasInScopes(const MDNode *Scopes,
+                                  const MDNode *NoAlias) const {
+  if (!Scopes || !NoAlias)
+    return true;
+
+  // Collect the set of scope domains relevant to the noalias scopes.
+  SmallPtrSet<const MDNode *, 16> Domains;
+  for (unsigned i = 0, ie = NoAlias->getNumOperands(); i != ie; ++i)
+    if (const MDNode *NAMD = dyn_cast<MDNode>(NoAlias->getOperand(i)))
+      if (const MDNode *Domain = AliasScopeNode(NAMD).getDomain())
+        Domains.insert(Domain);
+
+  // We alias unless, for some domain, the set of noalias scopes in that domain
+  // is a superset of the set of alias scopes in that domain.
+  for (const MDNode *Domain : Domains) {
+    SmallPtrSet<const MDNode *, 16> NANodes, ScopeNodes;
+    collectMDInDomain(NoAlias, Domain, NANodes);
+    collectMDInDomain(Scopes, Domain, ScopeNodes);
+    if (!ScopeNodes.size())
+      continue;
+
+    // To not alias, all of the nodes in ScopeNodes must be in NANodes.
+    bool FoundAll = true;
+    for (const MDNode *SMD : ScopeNodes)
+      if (!NANodes.count(SMD)) {
+        FoundAll = false;
+        break;
+      }
+
+    if (FoundAll)
+      return false;
+  }
+
+  return true;
+}
+
+AliasAnalysis::AliasResult
+ScopedNoAliasAA::alias(const Location &LocA, const Location &LocB) {
+  if (!EnableScopedNoAlias)
+    return AliasAnalysis::alias(LocA, LocB);
+
+  // Get the attached MDNodes.
+  const MDNode *AScopes = LocA.AATags.Scope,
+               *BScopes = LocB.AATags.Scope;
+
+  const MDNode *ANoAlias = LocA.AATags.NoAlias,
+               *BNoAlias = LocB.AATags.NoAlias;
+
+  if (!mayAliasInScopes(AScopes, BNoAlias))
+    return NoAlias;
+
+  if (!mayAliasInScopes(BScopes, ANoAlias))
+    return NoAlias;
+
+  // If they may alias, chain to the next AliasAnalysis.
+  return AliasAnalysis::alias(LocA, LocB);
+}
+
+bool ScopedNoAliasAA::pointsToConstantMemory(const Location &Loc,
+                                             bool OrLocal) {
+  return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
+}
+
+AliasAnalysis::ModRefBehavior
+ScopedNoAliasAA::getModRefBehavior(ImmutableCallSite CS) {
+  return AliasAnalysis::getModRefBehavior(CS);
+}
+
+AliasAnalysis::ModRefBehavior
+ScopedNoAliasAA::getModRefBehavior(const Function *F) {
+  return AliasAnalysis::getModRefBehavior(F);
+}
+
+AliasAnalysis::ModRefResult
+ScopedNoAliasAA::getModRefInfo(ImmutableCallSite CS, const Location &Loc) {
+  if (!EnableScopedNoAlias)
+    return AliasAnalysis::getModRefInfo(CS, Loc);
+
+  if (!mayAliasInScopes(Loc.AATags.Scope, CS.getInstruction()->getMetadata(
+                                              LLVMContext::MD_noalias)))
+    return NoModRef;
+
+  if (!mayAliasInScopes(
+          CS.getInstruction()->getMetadata(LLVMContext::MD_alias_scope),
+          Loc.AATags.NoAlias))
+    return NoModRef;
+
+  return AliasAnalysis::getModRefInfo(CS, Loc);
+}
+
+AliasAnalysis::ModRefResult
+ScopedNoAliasAA::getModRefInfo(ImmutableCallSite CS1, ImmutableCallSite CS2) {
+  if (!EnableScopedNoAlias)
+    return AliasAnalysis::getModRefInfo(CS1, CS2);
+
+  if (!mayAliasInScopes(
+          CS1.getInstruction()->getMetadata(LLVMContext::MD_alias_scope),
+          CS2.getInstruction()->getMetadata(LLVMContext::MD_noalias)))
+    return NoModRef;
+
+  if (!mayAliasInScopes(
+          CS2.getInstruction()->getMetadata(LLVMContext::MD_alias_scope),
+          CS1.getInstruction()->getMetadata(LLVMContext::MD_noalias)))
+    return NoModRef;
+
+  return AliasAnalysis::getModRefInfo(CS1, CS2);
+}
+