[Attributor] Deduce "no-capture" argument attribute

[jdoerfert]

Summary

Add the no-capture argument attribute deduction to the Attributor
fixpoint framework.

The new string attributed "no-capture-maybe-returned" is introduced to
allow deduction of no-capture through functions that "capture" an
argument but only by "returning" it.

Impact on the statistics (-stats) for LLVM-TS + Spec2006, ~7% more no-capute arguments:

CHANGED: attributor                   NumAttributesManifested                14323 ->      50306 (  +251.225%)                                                                                 
CHANGED: attributor                   NumAttributesValidFixpoint             39780 ->      81666 (  +105.294%)                                                                                 
  ADDED: attributor                   NumFnArgumentNoCapture                   n/a ->      35429
CHANGED: functionattrs                NumNoCapture                           32989 ->          2 (   -99.994%)

Note: both remaining function attribute deductions are deduction of no-capture even though it is already present.

[jdoerfert]

llvm/test/Transforms/FunctionAttrs/arg_nocapture.ll

86–87

The comments on this one were off from the very beginning, I'll fix them and there won't be a change during this commit.

llvm/test/Transforms/FunctionAttrs/nocapture.ll

137

So, the old FuncAttr deduction interleaves one of two memory behavior deductions with the capture analysis. With this patch capture analysis becomes obsolete, as the attributor added annotations, and certain memory behavior attributes are not detected anymore. There will be a memory behavior detection for the attributor soon which should make this problem go away.

[jdoerfert]

Closed a side-channel through "integers"

[jdoerfert]

Rebase

[jdoerfert]

@hfinkel ping

[jdoerfert]

Rebase

[jdoerfert]

Rebase

[jdoerfert]

Extracted CaptureTracking changes

[jdoerfert]

Add more test coverage and improve capture information based on dereferenceability

[jdoerfert]

Add tests accidentally removed

[jdoerfert]

rebase and update tests

[jdoerfert]

Update tests

[uenoku]

I think the logic is sound. It looks good to me.

llvm/lib/Transforms/IPO/Attributor.cpp

2618

Maybe we need an exact definition for no-capture-maybe-returned in LangRef.

2674

aswell

2761

Why IfNecessary? It seems there is no check.

2819

Align?

2864

liveness liveness

[jdoerfert]

llvm/lib/Transforms/IPO/Attributor.cpp

2618

I add a flag to disable manifestation in non-testing modes. If we add users we can add it as a enum attribute, for now it is internal.

llvm/include/llvm/Transforms/IPO/Attributor.h

if (isa<Instruction>(V))
       return cast<Instruction>(V).getFunction();
     return nullptr;
   }
   const Function *getAssociatedFunction() const {
     return const_cast<IRPosition *>(this)->getAssociatedFunction();
   }
   ///}
 
+  /// Return the associated argument, if any.
+  ///
+  ///{
+  Argument *getAssociatedArgument() {
+    if (auto *Arg = dyn_cast<Argument>(&getAnchorValue()))
+      return Arg;
+    int ArgNo = getArgNo();
+    if (ArgNo < 0)
+      return nullptr;
+    Function *AssociatedFn = getAssociatedFunction();
+    if (!AssociatedFn || AssociatedFn->arg_size() <= unsigned(ArgNo))
+      return nullptr;
+    return AssociatedFn->arg_begin() + ArgNo;
+  }
+  const Argument *getAssociatedArgument() const {
+    return const_cast<IRPosition *>(this)->getAssociatedArgument();
+  }
+  ///}
+
   /// Return the Function surrounding the anchor value.
   ///
   ///{
   Function *getAnchorScope() {
     Value &V = getAnchorValue();
     if (isa<Function>(V))
       return &cast<Function>(V);
     if (isa<Argument>(V))
struct AAAlign
 
   /// Create an abstract attribute view for the position \p IRP.
   static AAAlign &createForPosition(const IRPosition &IRP, Attributor &A);
 
   /// Unique ID (due to the unique address)
   static const char ID;
 };
 
+/// An abstract interface for all nocapture attributes.
+struct AANoCapture
+    : public IRAttribute<Attribute::NoCapture,
+                         StateWrapper<IntegerState, AbstractAttribute>> {
+  AANoCapture(const IRPosition &IRP) : IRAttribute(IRP) {}
+
+  /// State encoding bits. A set bit in the state means the property holds.
+  /// NO_CAPTURE is the best possible state, 0 the worst possible state.
+  enum {
+    NOT_CAPTURED_IN_MEM = 1 << 0,
+    NOT_CAPTURED_IN_INT = 1 << 1,
+    NOT_CAPTURED_IN_RET = 1 << 2,
+
+    /// If we do not capture the value in memory or through integers we can only
+    /// communicate it back as a derived pointer.
+    NO_CAPTURE_MAYBE_RETURNED = NOT_CAPTURED_IN_MEM | NOT_CAPTURED_IN_INT,
+
+    /// If we do not capture the value in memory, through integers, or as a
+    /// derived pointer we know it is not captured.
+    NO_CAPTURE =
+        NOT_CAPTURED_IN_MEM | NOT_CAPTURED_IN_INT | NOT_CAPTURED_IN_RET,
+  };
+
+  /// Return true if we know that the underlying value is not captured in its
+  /// respective scope.
+  bool isKnownNoCapture() const { return isKnown(NO_CAPTURE); }
+
+  /// Return true if we assume that the underlying value is not captured in its
+  /// respective scope.
+  bool isAssumedNoCapture() const { return isAssumed(NO_CAPTURE); }
+
+  /// Return true if we know that the underlying value is not captured in its
+  /// respective scope but we allow it to escape through a "return".
+  bool isKnownNoCaptureMaybeReturned() const {
+    return isKnown(NO_CAPTURE_MAYBE_RETURNED);
+  }
+
+  /// Return true if we assume that the underlying value is not captured in its
+  /// respective scope but we allow it to escape through a "return".
+  bool isAssumedNoCaptureMaybeReturned() const {
+    return isAssumed(NO_CAPTURE_MAYBE_RETURNED);
+  }
+
+  /// Create an abstract attribute view for the position \p IRP.
+  static AANoCapture &createForPosition(const IRPosition &IRP, Attributor &A);
+
+  /// Unique ID (due to the unique address)
+  static const char ID;
+};
+
 } // end namespace llvm
 
 #endif // LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H

llvm/lib/Transforms/IPO/Attributor.cpp

auto CheckReturnValue = [&](Value &RV) -> bool {
           return true;
 
       /// For now, we can only deduce noalias if we have call sites.
       /// FIXME: add more support.
       ImmutableCallSite ICS(&RV);
       if (!ICS)
         return false;
 
-      const auto &NoAliasAA =
-          A.getAAFor<AANoAlias>(*this, IRPosition::callsite_returned(ICS));
+      const IRPosition &RVPos = IRPosition::value(RV);
+      const auto &NoAliasAA = A.getAAFor<AANoAlias>(*this, RVPos);
       if (!NoAliasAA.isAssumedNoAlias())
         return false;
 
-      /// FIXME: We can improve capture check in two ways:
-      /// 1. Use the AANoCapture facilities.
-      /// 2. Use the location of return insts for escape queries.
-      if (PointerMayBeCaptured(&RV, /* ReturnCaptures */ false,
-                               /* StoreCaptures */ true))
-        return false;
-
-      return true;
+      const auto &NoCaptureAA = A.getAAFor<AANoCapture>(*this, RVPos);
+      return NoCaptureAA.isAssumedNoCaptureMaybeReturned();
     };
 
     if (!A.checkForAllReturnedValues(CheckReturnValue, *this))
       return indicatePessimisticFixpoint();
 
     return ChangeStatus::UNCHANGED;
   }
 
return clampStateAndIndicateChange(
         getState(),
         static_cast<const AANoReturn::StateType &>(FnAA.getState()));
   }
 
   /// See AbstractAttribute::trackStatistics()
   void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(noreturn); }
 };
 
+/// ----------------------- Variable Capturing ---------------------------------
+
+/// A class to hold the state of for no-capture attributes.
+struct AANoCaptureImpl : public AANoCapture {
+  AANoCaptureImpl(const IRPosition &IRP) : AANoCapture(IRP) {}
+
+  /// See AbstractAttribute::initialize(...).
+  void initialize(Attributor &A) override {
+    if (hasAttr(Attribute::NoCapture)) {
+      indicateOptimisticFixpoint();
+      return;
+    }
+
+    const IRPosition &IRP = getIRPosition();
+    const Function *F =
+        getArgNo() >= 0 ? IRP.getAssociatedFunction() : IRP.getAnchorScope();
+
+    // Check what state the associated function can actually capture.
+    if (F)
+      determineFunctionCaptureCapabilities(*F, *this);
+
+    if (!F || !F->hasExactDefinition())
+      indicatePessimisticFixpoint();
+  }
+
+  /// See AbstractAttribute::updateImpl(...).
+  ChangeStatus updateImpl(Attributor &A) override;
+
+  /// see AbstractAttribute::isAssumedNoCaptureMaybeReturned(...).
+  virtual void
+  getDeducedAttributes(LLVMContext &Ctx,
+                       SmallVectorImpl<Attribute> &Attrs) const override {
+    if (!isAssumedNoCaptureMaybeReturned())
+      return;
+
+    if (isAssumedNoCapture())
+      Attrs.emplace_back(Attribute::get(Ctx, Attribute::NoCapture));
+    else
+      Attrs.emplace_back(Attribute::get(Ctx, "no-capture-maybe-returned"));
+  }
+
+  /// Set the NOT_CAPTURED_IN_MEM and NOT_CAPTURED_IN_RET bits in \p Known
+  /// depending on the ability of the function associated with \p IRP to capture
+  /// state in memory and through "returning/throwing", respectively.
+  static void determineFunctionCaptureCapabilities(const Function &F,
+                                                   IntegerState &State) {
+    // TODO: Once we have memory behavior attributes we should use them here.
+
+    // If we know we cannot communicate or write to memory, we do not care about
+    // ptr2int anymore.
+    if (F.onlyReadsMemory() && F.doesNotThrow() &&
+        F.getReturnType()->isVoidTy()) {
+      State.addKnownBits(NO_CAPTURE);
+      return;
+    }
+
+    // A function cannot capture state in memory if it only reads memory, it can
+    // however return/throw state and the state might be influenced by the
+    // pointer value, e.g., loading from a returned pointer might reveal a bit.
+    if (F.onlyReadsMemory())
+      State.addKnownBits(NOT_CAPTURED_IN_MEM);
+
+    // A function cannot communicate state back if it does not through
+    // exceptions and doesn not return values.
+    if (F.doesNotThrow() && F.getReturnType()->isVoidTy())
+      State.addKnownBits(NOT_CAPTURED_IN_RET);
+  }
+
+  /// See AbstractState::getAsStr().
+  const std::string getAsStr() const override {
+    if (isKnownNoCapture())
+      return "known not-captured";
+    if (isAssumedNoCapture())
+      return "assumed not-captured";
+    if (isKnownNoCaptureMaybeReturned())
+      return "known not-captured-maybe-returned";
+    if (isAssumedNoCaptureMaybeReturned())
+      return "assumed not-captured-maybe-returned";
+    return "assumed-captured";
+  }
+};
+
+/// Attributor-aware capture tracker.
+struct AACaptureUseTracker final : public CaptureTracker {
+
+  /// Create a capture tracker that can lookup in-flight abstract attributes
+  /// through the attributor \p A.
+  ///
+  /// If a use leads to a potential capture, \p CapturedInMemory is set and the
+  /// search is stopped. If a use leads to a return instruction,
+  /// \p CommunicatedBack is set to true and \p CapturedInMemory is not changed.
+  /// If a use leads to a ptr2int which may capute the value,
+  /// \p CapturedInInteger is set. If a use is found that is currently assumed
+  /// "no-capture-maybe-returned", the user is added to the \p PotentialCopies
+  /// set. All values in \p PotentialCopies are later tracked aswell. For every
+  /// explored use we decrement \p RemainingUsesToExplore. Once it reaches 0,
+  /// the search is stopped with \p CapturedInMemory and \p CapturedInInteger
+  /// conservatively set to true.
+  AACaptureUseTracker(Attributor &A, AANoCapture &NoCaptureAA,
+                      const AAIsDead &IsDeadAA, IntegerState &State,
+                      SmallVectorImpl<const Value *> &PotentialCopies,
+                      unsigned &RemainingUsesToExplore)
+      : A(A), NoCaptureAA(NoCaptureAA), IsDeadAA(IsDeadAA), State(State),
+        PotentialCopies(PotentialCopies),
+        RemainingUsesToExplore(RemainingUsesToExplore) {}
+
+  /// Determine if \p V maybe captured. *Also updates the state!*
+  bool valueMayBeCaptured(const Value *V) {
+    if (V->getType()->isPointerTy()) {
+      PointerMayBeCaptured(V, this);
+    } else {
+      State.indicatePessimisticFixpoint();
+    }
+    return State.isAssumed(AANoCapture::NO_CAPTURE_MAYBE_RETURNED);
+  }
+
+  /// See CaptureTracker::tooManyUses().
+  void tooManyUses() override {
+    State.removeAssumedBits(AANoCapture::NO_CAPTURE);
+  }
+
+  bool isDereferenceableOrNull(Value *O, const DataLayout &DL) override {
+    if (CaptureTracker::isDereferenceableOrNull(O, DL))
+      return true;
+    const auto &DerefAA =
+        A.getAAFor<AADereferenceable>(NoCaptureAA, IRPosition::value(*O));
+    return DerefAA.getAssumedDereferenceableBytes();
+  }
+
+  /// See CaptureTracker::captured(...).
+  bool captured(const Use *U) override {
+    Instruction *UInst = cast<Instruction>(U->getUser());
+    LLVM_DEBUG(dbgs() << "Check use: " << *U->get() << " in " << *UInst
+                      << "\n");
+
+    // Because we may reuse the tracker multiple times we keep track of the
+    // number of explored uses ourselves as well.
+    if (RemainingUsesToExplore-- == 0) {
+      LLVM_DEBUG(dbgs() << " - too many uses to explore!\n");
+      return isCapturedIn(/* Memory */ true, /* Integer */ true,
+                          /* Return */ true);
+    }
+
+    // Deal with ptr2int by following uses.
+    if (isa<PtrToIntInst>(UInst)) {
+      LLVM_DEBUG(dbgs() << " - ptr2int assume the worst!\n");
+      return valueMayBeCaptured(UInst);
+    }
+
+    // Explicitly catch return instructions.
+    if (isa<ReturnInst>(UInst))
+      return isCapturedIn(/* Memory */ false, /* Integer */ false,
+                          /* Return */ true);
+
+    // For now we only use special logic for call sites. However, the tracker
+    // itself knows about a lot of other non-capturing cases already.
+    CallSite CS(UInst);
+    if (!CS || !CS.isArgOperand(U))
+      return isCapturedIn(/* Memory */ true, /* Integer */ true,
+                          /* Return */ true);
+
+    unsigned ArgNo = CS.getArgumentNo(U);
+    const IRPosition &CSArgPos = IRPosition::callsite_argument(CS, ArgNo);
+    // If we have a abstract no-capture attribute for the argument we can use
+    // it to justify a non-capture attribute here. This allows recursion!
+    auto &ArgNoCaptureAA = A.getAAFor<AANoCapture>(NoCaptureAA, CSArgPos);
+    if (ArgNoCaptureAA.isAssumedNoCapture())
+      return isCapturedIn(/* Memory */ false, /* Integer */ false,
+                          /* Return */ false);
+    if (ArgNoCaptureAA.isAssumedNoCaptureMaybeReturned()) {
+      addPotentialCopyIfNecessary(CS);
+      return isCapturedIn(/* Memory */ false, /* Integer */ false,
+                          /* Return */ false);
+    }
+
+    // Lastly, we could not find a reason no-capture can be assumed so we don't.
+    return isCapturedIn(/* Memory */ true, /* Integer */ true,
+                        /* Return */ true);
+  }
+
+  /// Register \p CS as potential copy of the value we are checking.
+  void addPotentialCopyIfNecessary(CallSite CS) {
+    PotentialCopies.push_back(CS.getInstruction());
+  }
+
+  /// See CaptureTracker::shouldExplore(...).
+  bool shouldExplore(const Use *U) override {
+    // Check liveness.
+    return !IsDeadAA.isAssumedDead(cast<Instruction>(U->getUser()));
+  }
+
+  /// Update the state according to \p CapturedInMem, \p CapturedInInt, and
+  /// \p CapturedInRet, then return the appropriate value for use in the
+  /// CaptureTracker::captured() interface.
+  bool isCapturedIn(bool CapturedInMem, bool CapturedInInt,
+                    bool CapturedInRet) {
+    LLVM_DEBUG(dbgs() << " - captures [Mem " << CapturedInMem << "|Int "
+                      << CapturedInInt << "|Ret " << CapturedInRet << "]\n");
+    if (CapturedInMem)
+      State.removeAssumedBits(AANoCapture::NOT_CAPTURED_IN_MEM);
+    if (CapturedInInt)
+      State.removeAssumedBits(AANoCapture::NOT_CAPTURED_IN_INT);
+    if (CapturedInRet)
+      State.removeAssumedBits(AANoCapture::NOT_CAPTURED_IN_RET);
+    return !State.isAssumed(AANoCapture::NO_CAPTURE_MAYBE_RETURNED);
+  }
+
+private:
+  /// The attributor providing in-flight abstract attributes.
+  Attributor &A;
+
+  /// The abstract attribute currently updated.
+  AANoCapture &NoCaptureAA;
+
+  /// The abstract liveness state.
+  const AAIsDead &IsDeadAA;
+
+  /// The state currently updated.
+  IntegerState &State;
+
+  /// Set of potential copies of the tracked value.
+  SmallVectorImpl<const Value *> &PotentialCopies;
+
+  /// Global counter to limit the number of explored uses.
+  unsigned &RemainingUsesToExplore;
+};
+
+ChangeStatus AANoCaptureImpl::updateImpl(Attributor &A) {
+  const IRPosition &IRP = getIRPosition();
+  const Value *V =
+      getArgNo() >= 0 ? IRP.getAssociatedArgument() : &IRP.getAssociatedValue();
+  if (!V)
+    return indicatePessimisticFixpoint();
+
+  const Function *F =
+      getArgNo() >= 0 ? IRP.getAssociatedFunction() : IRP.getAnchorScope();
+  assert(F && "Expected a function!");
+  const auto &IsDeadAA = A.getAAFor<AAIsDead>(*this, IRPosition::function(*F));
+
+  AAAlign::StateType T;
+  // TODO: Once we have memory behavior attributes we should use them here
+  // similar to the reasoning in
+  // AANoCaptureImpl::determineFunctionCaptureCapabilities(...).
+
+  // TODO: Use the AAReturnedValues to learn if the argument can return or
+  // not.
+
+  // Use the CaptureTracker interface and logic with the specialized tracker,
+  // defined in AACaptureUseTracker, that can look at in-flight abstract
+  // attributes and directly updates the assumed state.
+  SmallVector<const Value *, 4> PotentialCopies;
+  unsigned RemainingUsesToExplore = DefaultMaxUsesToExplore;
+  AACaptureUseTracker Tracker(A, *this, IsDeadAA, T, PotentialCopies,
+                              RemainingUsesToExplore);
+
+  // Check all potential copies of the associated value until we can assume
+  // none will be captured or we have to assume at least one might be.
+  unsigned Idx = 0;
+  PotentialCopies.push_back(V);
+  while (T.isAssumed(NO_CAPTURE_MAYBE_RETURNED) && Idx < PotentialCopies.size())
+    Tracker.valueMayBeCaptured(PotentialCopies[Idx++]);
+
+  AAAlign::StateType &S = getState();
+  auto Assumed = S.getAssumed();
+  S.intersectAssumedBits(T.getAssumed());
+  return Assumed == S.getAssumed() ? ChangeStatus::UNCHANGED
+                                   : ChangeStatus::CHANGED;
+}
+
+/// NoCapture attribute for function arguments.
+struct AANoCaptureArgument final : AANoCaptureImpl {
+  AANoCaptureArgument(const IRPosition &IRP) : AANoCaptureImpl(IRP) {}
+
+  /// See AbstractAttribute::trackStatistics()
+  void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(nocapture) }
+};
+
+/// NoCapture attribute for call site arguments.
+struct AANoCaptureCallSiteArgument final : AANoCaptureImpl {
+  AANoCaptureCallSiteArgument(const IRPosition &IRP) : AANoCaptureImpl(IRP) {}
+
+  /// See AbstractAttribute::updateImpl(...).
+  ChangeStatus updateImpl(Attributor &A) override {
+    // TODO: Once we have call site specific value information we can provide
+    //       call site specific liveness liveness information and then it makes
+    //       sense to specialize attributes for call sites arguments instead of
+    //       redirecting requests to the callee argument.
+    Argument *Arg = getAssociatedArgument();
+    if (!Arg)
+      return indicatePessimisticFixpoint();
+    const IRPosition &ArgPos = IRPosition::argument(*Arg);
+    auto &ArgAA = A.getAAFor<AANoCapture>(*this, ArgPos);
+    return clampStateAndIndicateChange(
+        getState(),
+        static_cast<const AANoCapture::StateType &>(ArgAA.getState()));
+  }
+
+  /// See AbstractAttribute::trackStatistics()
+  void trackStatistics() const override{STATS_DECLTRACK_CSARG_ATTR(nocapture)};
+};
+
+/// NoCapture attribute for floating values.
+struct AANoCaptureFloating final : AANoCaptureImpl {
+  AANoCaptureFloating(const IRPosition &IRP) : AANoCaptureImpl(IRP) {}
+
+  /// See AbstractAttribute::trackStatistics()
+  void trackStatistics() const override {
+    STATS_DECLTRACK_FLOATING_ATTR(nocapture)
+  }
+};
+
+/// NoCapture attribute for function return value.
+struct AANoCaptureReturned final : AANoCaptureImpl {
+  AANoCaptureReturned(const IRPosition &IRP) : AANoCaptureImpl(IRP) {
+    llvm_unreachable("NoCapture is not applicable to function returns!");
+  }
+
+  /// See AbstractAttribute::initialize(...).
+  void initialize(Attributor &A) override {
+    llvm_unreachable("NoCapture is not applicable to function returns!");
+  }
+
+  /// See AbstractAttribute::updateImpl(...).
+  ChangeStatus updateImpl(Attributor &A) override {
+    llvm_unreachable("NoCapture is not applicable to function returns!");
+  }
+
+  /// See AbstractAttribute::trackStatistics()
+  void trackStatistics() const override {}
+};
+
+/// NoCapture attribute deduction for a call site return value.
+struct AANoCaptureCallSiteReturned final : AANoCaptureImpl {
+  AANoCaptureCallSiteReturned(const IRPosition &IRP) : AANoCaptureImpl(IRP) {}
+
+  /// See AbstractAttribute::trackStatistics()
+  void trackStatistics() const override {
+    STATS_DECLTRACK_CSRET_ATTR(nocapture)
+  }
+};
+
 /// ----------------------------------------------------------------------------
 ///                               Attributor
 /// ----------------------------------------------------------------------------
 
 bool Attributor::isAssumedDead(const AbstractAttribute &AA,
                                const AAIsDead *LivenessAA) {
   const Instruction *CtxI = AA.getIRPosition().getCtxI();
   if (!CtxI)
if (Arg.getType()->isPointerTy()) {
       // Every argument with pointer type might be marked noalias.
       checkAndRegisterAA<AANoAliasArgument>(ArgPos, *this, Whitelist);
 
       // Every argument with pointer type might be marked dereferenceable.
       checkAndRegisterAA<AADereferenceableArgument>(ArgPos, *this, Whitelist);
 
       // Every argument with pointer type might be marked align.
       checkAndRegisterAA<AAAlignArgument>(ArgPos, *this, Whitelist);
+
+      // Every argument with pointer type might be marked nocapture.
+      checkAndRegisterAA<AANoCaptureArgument>(ArgPos, *this, Whitelist);
     }
   }
 
   // Walk all instructions to find more attribute opportunities and also
   // interesting instructions that might be queried by abstract attributes
   // during their initialization or update.
   auto &ReadOrWriteInsts = InfoCache.FuncRWInstsMap[&F];
   auto &InstOpcodeMap = InfoCache.FuncInstOpcodeMap[&F];

 const char AANonNull::ID = 0;
 const char AANoRecurse::ID = 0;
 const char AAWillReturn::ID = 0;
 const char AANoAlias::ID = 0;
 const char AANoReturn::ID = 0;
 const char AAIsDead::ID = 0;
 const char AADereferenceable::ID = 0;
 const char AAAlign::ID = 0;
+const char AANoCapture::ID = 0;
 
 // Macro magic to create the static generator function for attributes that
 // follow the naming scheme.
 
 #define SWITCH_PK_INV(CLASS, PK, POS_NAME)                                     \
   case IRPosition::PK:                                                         \
     llvm_unreachable("Cannot create " #CLASS " for a " POS_NAME " position!");
 

 CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoReturn)
 CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAIsDead)
 CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAReturnedValues)
 
 CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANonNull)
 CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoAlias)
 CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AADereferenceable)
 CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAAlign)
+CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoCapture)
 
 #undef CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION
 #undef CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION
 #undef SWITCH_PK_CREATE
 #undef SWITCH_PK_INV
 
 INITIALIZE_PASS_BEGIN(AttributorLegacyPass, "attributor",
                       "Deduce and propagate attributes", false, false)
 INITIALIZE_PASS_END(AttributorLegacyPass, "attributor",
                     "Deduce and propagate attributes", false, false)

llvm/test/Transforms/FunctionAttrs/align.ll

 ; RUN: opt -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=6 -S < %s | FileCheck %s --check-prefix=ATTRIBUTOR
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
 ; Test cases specifically designed for "align" attribute.
 ; We use FIXME's to indicate problems and missing attributes.
 
 
 ; TEST 1
-; ATTRIBUTOR: define align 8 i32* @test1(i32* returned align 8 %0)
+; ATTRIBUTOR: define align 8 i32* @test1(i32* returned align 8 "no-capture-maybe-returned" %0)
 define i32* @test1(i32* align 8 %0) #0 {
   ret i32* %0
 }
 
 ; TEST 2
-; ATTRIBUTOR: define i32* @test2(i32* returned %0)
+; ATTRIBUTOR: define i32* @test2(i32* returned "no-capture-maybe-returned" %0)
 define i32* @test2(i32* %0) #0 {
   ret i32* %0
 }
 
 ; TEST 3
-; ATTRIBUTOR: define align 4 i32* @test3(i32* align 8 %0, i32* align 4 %1, i1 %2)
+; ATTRIBUTOR: define align 4 i32* @test3(i32* align 8 "no-capture-maybe-returned" %0, i32* align 4 "no-capture-maybe-returned" %1, i1 %2)
 define i32* @test3(i32* align 8 %0, i32* align 4 %1, i1 %2) #0 {
   %ret = select i1 %2, i32* %0, i32* %1
   ret i32* %ret
 }
 
 ; TEST 4
-; ATTRIBUTOR: define align 32 i32* @test4(i32* align 32 %0, i32* align 32 %1, i1 %2)
+; ATTRIBUTOR: define align 32 i32* @test4(i32* align 32 "no-capture-maybe-returned" %0, i32* align 32 "no-capture-maybe-returned" %1, i1 %2)
 define i32* @test4(i32* align 32 %0, i32* align 32 %1, i1 %2) #0 {
   %ret = select i1 %2, i32* %0, i32* %1
   ret i32* %ret
 }
 
 ; TEST 5
 declare i32* @unknown()
 declare align 8 i32* @align8()

 ;     return a?&a1: f1(&a2);
 ; }
 
 @a1 = common global i8 0, align 8
 @a2 = common global i8 0, align 16
 
 ; Function Attrs: nounwind readnone ssp uwtable
 define internal i8* @f1(i8* readnone %0) local_unnamed_addr #0 {
-; ATTRIBUTOR: define internal nonnull align 8 dereferenceable(1) i8* @f1(i8* nonnull readnone align 8 dereferenceable(1) %0)
+; ATTRIBUTOR: define internal nonnull align 8 dereferenceable(1) i8* @f1(i8* nonnull readnone align 8 dereferenceable(1) "no-capture-maybe-returned" %0)
   %2 = icmp eq i8* %0, null
   br i1 %2, label %3, label %5
 
 ; <label>:3:                                      ; preds = %1
 ; ATTRIBUTOR: %4 = tail call i8* @f2(i8* nonnull align 8 dereferenceable(1) @a1)
   %4 = tail call i8* @f2(i8* nonnull @a1)
 ; ATTRIBUTOR: %l = load i8, i8* %4, align 8
   %l = load i8, i8* %4
   br label %5
 
 ; <label>:5:                                      ; preds = %1, %3
   %6 = phi i8* [ %4, %3 ], [ %0, %1 ]
   ret i8* %6
 }
 
 ; Function Attrs: nounwind readnone ssp uwtable
 define internal i8* @f2(i8* readnone %0) local_unnamed_addr #0 {
-; ATTRIBUTOR: define internal nonnull align 8 dereferenceable(1) i8* @f2(i8* nonnull readnone align 8 dereferenceable(1) %0)
+; ATTRIBUTOR: define internal nonnull align 8 dereferenceable(1) i8* @f2(i8* nonnull readnone align 8 dereferenceable(1) "no-capture-maybe-returned" %0)
   %2 = icmp eq i8* %0, null
   br i1 %2, label %5, label %3
 
 ; <label>:3:                                      ; preds = %1
 
-; ATTRIBUTOR: %4 = tail call i8* @f1(i8* nonnull align 8 dereferenceable(1) %0)
+; ATTRIBUTOR: %4 = tail call i8* @f1(i8* nonnull align 8 dereferenceable(1) "no-capture-maybe-returned" %0)
   %4 = tail call i8* @f1(i8* nonnull %0)
   br label %7
 
 ; <label>:5:                                      ; preds = %1
 ; ATTRIBUTOR: %6 = tail call i8* @f3(i8* nonnull align 16 dereferenceable(1) @a2)
   %6 = tail call i8* @f3(i8* nonnull @a2)
   br label %7
 
 ; <label>:7:                                      ; preds = %5, %3
   %8 = phi i8* [ %4, %3 ], [ %6, %5 ]
   ret i8* %8
 }
 
 ; Function Attrs: nounwind readnone ssp uwtable
 define internal i8* @f3(i8* readnone %0) local_unnamed_addr #0 {
-; ATTRIBUTOR: define internal nonnull align 8 dereferenceable(1) i8* @f3(i8* nonnull readnone align 16 dereferenceable(1) %0)
+; ATTRIBUTOR: define internal nonnull align 8 dereferenceable(1) i8* @f3(i8* nocapture nonnull readnone align 16 dereferenceable(1) %0)
   %2 = icmp eq i8* %0, null
   br i1 %2, label %3, label %5
 
 ; <label>:3:                                      ; preds = %1
 ; ATTRIBUTOR: %4 = tail call i8* @f1(i8* nonnull align 16 dereferenceable(1) @a2)
   %4 = tail call i8* @f1(i8* nonnull @a2)
   br label %5
 
 ; <label>:5:                                      ; preds = %1, %3
   %6 = phi i8* [ %4, %3 ], [ @a1, %1 ]
   ret i8* %6
 }
 
 ; TEST 7
 ; Better than IR information
-; ATTRIBUTOR: define align 32 i32* @test7(i32* returned align 32 %p)
+; ATTRIBUTOR: define align 32 i32* @test7(i32* returned align 32 "no-capture-maybe-returned" %p)
 define align 4 i32* @test7(i32* align 32 %p) #0 {
   tail call i8* @f1(i8* align 8 dereferenceable(1) @a1)
   ret i32* %p
 }
 
 
 ; TEST 8
 define void @test8_helper() {
   %ptr0 = tail call i32* @unknown()
   %ptr1 = tail call align 4 i32* @unknown()
   %ptr2 = tail call align 8 i32* @unknown()
 
   tail call void @test8(i32* %ptr1, i32* %ptr1, i32* %ptr0)
 ; ATTRIBUTOR: tail call void @test8(i32* align 4 %ptr1, i32* align 4 %ptr1, i32* %ptr0)
   tail call void @test8(i32* %ptr2, i32* %ptr1, i32* %ptr1)
 ; ATTRIBUTOR: tail call void @test8(i32* align 8 %ptr2, i32* align 4 %ptr1, i32* align 4 %ptr1)
   tail call void @test8(i32* %ptr2, i32* %ptr1, i32* %ptr1)
 ; ATTRIBUTOR: tail call void @test8(i32* align 8 %ptr2, i32* align 4 %ptr1, i32* align 4 %ptr1)
   ret void
 }
 
 define internal void @test8(i32* %a, i32* %b, i32* %c) {
-; ATTRIBUTOR: define internal void @test8(i32* align 4 %a, i32* align 4 %b, i32* %c)
+; ATTRIBUTOR: define internal void @test8(i32* nocapture align 4 %a, i32* nocapture align 4 %b, i32* nocapture %c)
   ret void
 }
 
 declare void @test9_helper(i32* %A)
 define void @test9_traversal(i1 %c, i32* align 4 %B, i32* align 8 %C) {
   %sel = select i1 %c, i32* %B, i32* %C
   call void @test9_helper(i32* %sel)
   ret void
 }
 
 ; FIXME: This will work with an upcoming patch (D66618 or similar)
-;             define align 32 i32* @test10a(i32* align 32 %p)
-; ATTRIBUTOR: define i32* @test10a(i32* align 32 %p)
+;             define align 32 i32* @test10a(i32* align 32 "no-capture-maybe-returned" %p)
+; ATTRIBUTOR: define i32* @test10a(i32* align 32 "no-capture-maybe-returned" %p)
 define i32* @test10a(i32* align 32 %p) {
 ; ATTRIBUTOR: %l = load i32, i32* %p, align 32
   %l = load i32, i32* %p
   %c = icmp eq i32 %l, 0
   br i1 %c, label %t, label %f
 t:
   %r = call i32* @test10a(i32* %p)
 ; FIXME: This will work with an upcoming patch (D66618 or similar)
; ATTRIBUTOR: store i32 -1, i32* %g1
   store i32 -1, i32* %g1
   br label %e
 e:
   %phi = phi i32* [%g0, %t], [%g1, %f]
   ret i32* %phi
 }
 
 ; FIXME: This will work with an upcoming patch (D66618 or similar)
-;             define align 32 i32* @test10b(i32* align 32 %p)
-; ATTRIBUTOR: define i32* @test10b(i32* align 32 %p)
+;             define align 32 i32* @test10b(i32* align 32 "no-capture-maybe-returned" %p)
+; ATTRIBUTOR: define i32* @test10b(i32* align 32 "no-capture-maybe-returned" %p)
 define i32* @test10b(i32* align 32 %p) {
 ; ATTRIBUTOR: %l = load i32, i32* %p, align 32
   %l = load i32, i32* %p
   %c = icmp eq i32 %l, 0
   br i1 %c, label %t, label %f
 t:
   %r = call i32* @test10b(i32* %p)
 ; FIXME: This will work with an upcoming patch (D66618 or similar)

llvm/test/Transforms/FunctionAttrs/arg_nocapture.ll

 ; int* srec16(int* a) {
 ;   return srec16(srec16(srec16(srec16(
 ;          srec16(srec16(srec16(srec16(
 ;          srec16(srec16(srec16(srec16(
 ;          srec16(srec16(srec16(srec16(
 ;                        a
 ;          ))))))))))))))));
 ; }
 ;
 ; Other arguments are possible here due to the no-return behavior.
 ;
 ; CHECK: define noalias nonnull align 536870912 dereferenceable(4294967295) i32* @srec16(i32* nocapture readnone %a)
 define i32* @srec16(i32* %a) #0 {
 entry:
   %call = call i32* @srec16(i32* %a)
 ; CHECK:      %call = call i32* @srec16(i32* %a)
 ; CHECK-NEXT: unreachable
   %call1 = call i32* @srec16(i32* %call)
; CHECK-NEXT: unreachable
   %call13 = call i32* @srec16(i32* %call12)
   %call14 = call i32* @srec16(i32* %call13)
   %call15 = call i32* @srec16(i32* %call14)
   ret i32* %call15
 }
 
 ; TEST SCC with various calls, casts, and comparisons agains NULL
 ;
-; FIXME: no-capture missing for %a
-; CHECK: define float* @scc_A(i32* readnone returned %a)
+; CHECK: define dereferenceable_or_null(4) float* @scc_A(i32* readnone returned dereferenceable_or_null(4) "no-capture-maybe-returned" %a)
 ;
-; FIXME: no-capture missing for %a
-; CHECK: define i64* @scc_B(double* readnone returned %a)
+; CHECK: define dereferenceable_or_null(8) i64* @scc_B(double* readnone returned dereferenceable_or_null(8) "no-capture-maybe-returned" %a)
 ;
 ; FIXME: readnone missing for %s
-; FIXME: no-capture missing for %a
-; CHECK: define i8* @scc_C(i16* returned %a)
+; CHECK: define dereferenceable_or_null(2) i8* @scc_C(i16* returned dereferenceable_or_null(2) "no-capture-maybe-returned" %a)
 ;
 ; float *scc_A(int *a) {
 ;   return (float*)(a ? (int*)scc_A((int*)scc_B((double*)scc_C((short*)a))) : a);
 ; }
 ;
 ; long *scc_B(double *a) {
 ;   return (long*)(a ? scc_C((short*)scc_B((double*)scc_A((int*)a))) : a);
 ; }
 ;
 ; void *scc_C(short *a) {
 ;   return scc_A((int*)(scc_A(a) ? scc_B((double*)a) : scc_C(a)));
 ; }
-define float* @scc_A(i32* %a) {
+define float* @scc_A(i32* dereferenceable_or_null(4) %a) {
 entry:
   %tobool = icmp ne i32* %a, null
   br i1 %tobool, label %cond.true, label %cond.false
 
 cond.true:                                        ; preds = %entry
   %0 = bitcast i32* %a to i16*
   %call = call i8* @scc_C(i16* %0)
   %1 = bitcast i8* %call to double*
   %call1 = call i64* @scc_B(double* %1)
   %2 = bitcast i64* %call1 to i32*
   %call2 = call float* @scc_A(i32* %2)
   %3 = bitcast float* %call2 to i32*
   br label %cond.end
 
 cond.false:                                       ; preds = %entry
   br label %cond.end
 
 cond.end:                                         ; preds = %cond.false, %cond.true
   %cond = phi i32* [ %3, %cond.true ], [ %a, %cond.false ]
   %4 = bitcast i32* %cond to float*
   ret float* %4
 }
 
-define i64* @scc_B(double* %a) {
+define i64* @scc_B(double* dereferenceable_or_null(8) %a) {
 entry:
   %tobool = icmp ne double* %a, null
   br i1 %tobool, label %cond.true, label %cond.false
 
 cond.true:                                        ; preds = %entry
   %0 = bitcast double* %a to i32*
   %call = call float* @scc_A(i32* %0)
   %1 = bitcast float* %call to double*
   %call1 = call i64* @scc_B(double* %1)
   %2 = bitcast i64* %call1 to i16*
   %call2 = call i8* @scc_C(i16* %2)
   br label %cond.end
 
 cond.false:                                       ; preds = %entry
   %3 = bitcast double* %a to i8*
   br label %cond.end
 
 cond.end:                                         ; preds = %cond.false, %cond.true
   %cond = phi i8* [ %call2, %cond.true ], [ %3, %cond.false ]
   %4 = bitcast i8* %cond to i64*
   ret i64* %4
 }
 
-define i8* @scc_C(i16* %a) {
+define i8* @scc_C(i16* dereferenceable_or_null(2) %a) {
 entry:
   %bc = bitcast i16* %a to i32*
   %call = call float* @scc_A(i32* %bc)
   %bc2 = bitcast float* %call to i8*
   %tobool = icmp ne i8* %bc2, null
   br i1 %tobool, label %cond.true, label %cond.false
 
 cond.true:                                        ; preds = %entry

 ; TEST "captured" only through return
 ;
 ; long *not_captured_but_returned_0(long *a) {
 ;   *a1 = 0;
 ;   return a;
 ; }
 ;
 ; There should *not* be a no-capture attribute on %a
-; CHECK: define i64* @not_captured_but_returned_0(i64* returned %a)
+; CHECK: define i64* @not_captured_but_returned_0(i64* returned "no-capture-maybe-returned" %a)
 define i64* @not_captured_but_returned_0(i64* %a) #0 {
 entry:
   store i64 0, i64* %a, align 8
   ret i64* %a
 }
 
 ; TEST "captured" only through return
 ;
 ; long *not_captured_but_returned_1(long *a) {
 ;   *(a+1) = 1;
 ;   return a + 1;
 ; }
 ;
 ; There should *not* be a no-capture attribute on %a
-; CHECK: define nonnull i64* @not_captured_but_returned_1(i64* %a)
+; CHECK: define nonnull i64* @not_captured_but_returned_1(i64* "no-capture-maybe-returned" %a)
 define i64* @not_captured_but_returned_1(i64* %a) #0 {
 entry:
   %add.ptr = getelementptr inbounds i64, i64* %a, i64 1
   store i64 1, i64* %add.ptr, align 8
   ret i64* %add.ptr
 }
 
 ; TEST calls to "captured" only through return functions
 ;
 ; void test_not_captured_but_returned_calls(long *a) {
 ;   not_captured_but_returned_0(a);
 ;   not_captured_but_returned_1(a);
 ; }
 ;
 ; FIXME: no-capture missing for %a
-; CHECK: define void @test_not_captured_but_returned_calls(i64* %a)
+; CHECK: define void @test_not_captured_but_returned_calls(i64* nocapture %a)
 define void @test_not_captured_but_returned_calls(i64* %a) #0 {
 entry:
   %call = call i64* @not_captured_but_returned_0(i64* %a)
   %call1 = call i64* @not_captured_but_returned_1(i64* %a)
   ret void
 }
 
 ; TEST "captured" only through transitive return
 ;
 ; long* negative_test_not_captured_but_returned_call_0a(long *a) {
 ;   return not_captured_but_returned_0(a);
 ; }
 ;
 ; There should *not* be a no-capture attribute on %a
-; CHECK: define i64* @negative_test_not_captured_but_returned_call_0a(i64* returned %a)
+; CHECK: define i64* @negative_test_not_captured_but_returned_call_0a(i64* returned "no-capture-maybe-returned" %a)
 define i64* @negative_test_not_captured_but_returned_call_0a(i64* %a) #0 {
 entry:
   %call = call i64* @not_captured_but_returned_0(i64* %a)
   ret i64* %call
 }
 
 ; TEST captured through write
 ;

 
 ; TEST "captured" only through transitive return
 ;
 ; long* negative_test_not_captured_but_returned_call_1a(long *a) {
 ;   return not_captured_but_returned_1(a);
 ; }
 ;
 ; There should *not* be a no-capture attribute on %a
-; CHECK: define nonnull i64* @negative_test_not_captured_but_returned_call_1a(i64* %a)
+; CHECK: define nonnull i64* @negative_test_not_captured_but_returned_call_1a(i64* "no-capture-maybe-returned" %a)
 define i64* @negative_test_not_captured_but_returned_call_1a(i64* %a) #0 {
 entry:
   %call = call i64* @not_captured_but_returned_1(i64* %a)
   ret i64* %call
 }
 
 ; TEST captured through write
 ;

llvm/test/Transforms/FunctionAttrs/arg_returned.ll

return:                                           ; preds = %cond.end, %if.then3, %if.then
   %retval.0 = phi i32 [ %call1, %if.then ], [ %call11, %if.then3 ], [ %cond, %cond.end ]
   ret i32 %retval.0
 }
 
 
 ; TEST SCC test returning a pointer value argument
 ;
 ; BOTH: Function Attrs: nofree noinline norecurse nosync nounwind readnone uwtable
-; BOTH-NEXT: define double* @ptr_sink_r0(double* readnone returned %r)
+; BOTH-NEXT: define double* @ptr_sink_r0(double* readnone returned "no-capture-maybe-returned" %r)
 ; BOTH: Function Attrs: nofree noinline nosync nounwind readnone uwtable
 ; BOTH-NEXT: define double* @ptr_scc_r1(double* %a, double* readnone returned %r, double* nocapture readnone %b)
 ; BOTH: Function Attrs: nofree noinline nosync nounwind readnone uwtable
 ; BOTH-NEXT: define double* @ptr_scc_r2(double* readnone %a, double* readnone %b, double* readnone returned %r)
 ;
 ; FNATTR: define double* @ptr_sink_r0(double* readnone returned %r)
 ; FNATTR: define double* @ptr_scc_r1(double* %a, double* readnone %r, double* nocapture readnone %b)
 ; FNATTR: define double* @ptr_scc_r2(double* readnone %a, double* readnone %b, double* readnone %r)
 ;
 ; ATTRIBUTOR: Function Attrs: nofree noinline nosync nounwind uwtable
-; ATTRIBUTOR-NEXT: define double* @ptr_sink_r0(double* returned %r)
+; ATTRIBUTOR-NEXT: define double* @ptr_sink_r0(double* returned "no-capture-maybe-returned" %r)
 ; ATTRIBUTOR: Function Attrs: nofree noinline nosync nounwind uwtable
-; ATTRIBUTOR-NEXT: define double* @ptr_scc_r1(double* %a, double* returned %r, double* %b)
+; ATTRIBUTOR-NEXT: define double* @ptr_scc_r1(double* %a, double* returned %r, double* nocapture %b)
 ; ATTRIBUTOR: Function Attrs: nofree noinline nosync nounwind uwtable
 ; ATTRIBUTOR-NEXT: define double* @ptr_scc_r2(double* %a, double* %b, double* returned %r)
 ;
 ; double* ptr_scc_r1(double* a, double* b, double* r);
 ; double* ptr_scc_r2(double* a, double* b, double* r);
 ;
 ; __attribute__((noinline)) double* ptr_sink_r0(double* r) {
 ;   return r;

 ; TEST a no-return singleton SCC
 ;
 ; int* rt0(int *a) {
 ;   return *a ? a : rt0(a);
 ; }
 ;
 ; FNATTR:  define i32* @rt0(i32* readonly %a)
 ; BOTH: Function Attrs: nofree noinline noreturn nosync nounwind readonly uwtable
-; BOTH-NEXT:    define noalias nonnull align 536870912 dereferenceable(4294967295) i32* @rt0(i32* readonly %a)
+; BOTH-NEXT:    define noalias nonnull align 536870912 dereferenceable(4294967295) i32* @rt0(i32* nocapture readonly %a)
 define i32* @rt0(i32* %a) #0 {
 entry:
   %v = load i32, i32* %a, align 4
   %tobool = icmp ne i32 %v, 0
   %call = call i32* @rt0(i32* %a)
   %sel = select i1 %tobool, i32* %a, i32* %call
   ret i32* %sel
 }
entry:
   ret i32* %sel
 }
 
 ; TEST another SCC test
 ;
 ; FNATTR:  define i32* @rt2_helper(i32* %a)
 ; FNATTR:  define i32* @rt2(i32* readnone %a, i32* readnone %b)
 ; BOTH:    define i32* @rt2_helper(i32* returned %a)
-; BOTH:    define i32* @rt2(i32* readnone %a, i32* readnone %b)
+; BOTH:    define i32* @rt2(i32* readnone %a, i32* readnone "no-capture-maybe-returned" %b)
 define i32* @rt2_helper(i32* %a) #0 {
 entry:
   %call = call i32* @rt2(i32* %a, i32* %a)
   ret i32* %call
 }
 
 define i32* @rt2(i32* %a, i32 *%b) #0 {
 entry:
   %cmp = icmp eq i32* %a, null
   br i1 %cmp, label %if.then, label %if.end
 
 if.then:
   %call = call i32* @rt2_helper(i32* %a)
   br label %if.end
 
 if.end:
   %sel = phi i32* [ %b, %entry], [%call, %if.then]
   ret i32* %sel
 }
 
 ; TEST another SCC test
 ;
 ; FNATTR:  define i32* @rt3_helper(i32* %a, i32* %b)
 ; FNATTR:  define i32* @rt3(i32* readnone %a, i32* readnone %b)
-; BOTH:    define i32* @rt3_helper(i32* %a, i32* returned %b)
-; BOTH:    define i32* @rt3(i32* readnone %a, i32* readnone returned %b)
+; BOTH:    define i32* @rt3_helper(i32* %a, i32* returned "no-capture-maybe-returned" %b)
+; BOTH:    define i32* @rt3(i32* readnone %a, i32* readnone returned "no-capture-maybe-returned" %b)
 define i32* @rt3_helper(i32* %a, i32* %b) #0 {
 entry:
   %call = call i32* @rt3(i32* %a, i32* %b)
   ret i32* %call
 }
 
 define i32* @rt3(i32* %a, i32 *%b) #0 {
 entry:

 ;  int* calls_unknown_fn(int *r) {
 ;    unknown_fn(&calls_unknown_fn);
 ;    return r;
 ;  }
 ;
 ; BOTH: declare void @unknown_fn(i32* (i32*)*)
 ;
 ; BOTH:       Function Attrs: noinline nounwind uwtable
-; BOTH-NEXT:  define i32* @calls_unknown_fn(i32* readnone returned %r)
+; BOTH-NEXT:  define i32* @calls_unknown_fn(i32* readnone returned "no-capture-maybe-returned" %r)
 ; FNATTR:     define i32* @calls_unknown_fn(i32* readnone returned %r)
-; ATTRIBUTOR: define i32* @calls_unknown_fn(i32* returned %r)
+; ATTRIBUTOR: define i32* @calls_unknown_fn(i32* returned "no-capture-maybe-returned" %r)
 declare void @unknown_fn(i32* (i32*)*) #0
 
 define i32* @calls_unknown_fn(i32* %r) #0 {
   tail call void @unknown_fn(i32* (i32*)* nonnull @calls_unknown_fn)
   ret i32* %r
 }
 
 

 
 ; TEST returned argument goes through bitcasts
 ;
 ; double* bitcast(int* b) {
 ;   return (double*)b;
 ; }
 ;
 ; BOTH: Function Attrs: nofree noinline norecurse nosync nounwind readnone uwtable
-; BOTH-NEXT:  define double* @bitcast(i32* readnone returned %b)
+; BOTH-NEXT:  define double* @bitcast(i32* readnone returned "no-capture-maybe-returned" %b)
 ;
 ; FNATTR:     define double* @bitcast(i32* readnone %b)
 ;
 ; ATTRIBUTOR: Function Attrs: nofree noinline nosync nounwind uwtable
-; ATTRIBUTOR-NEXT: define double* @bitcast(i32* returned %b)
+; ATTRIBUTOR-NEXT: define double* @bitcast(i32* returned "no-capture-maybe-returned" %b)
 define double* @bitcast(i32* %b) #0 {
 entry:
   %bc0 = bitcast i32* %b to double*
   ret double* %bc0
 }
 
 
 ; TEST returned argument goes through select and phi interleaved with bitcasts

llvm/test/Transforms/FunctionAttrs/dereferenceable.ll

 ; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=4 -S < %s | FileCheck %s --check-prefixes=ATTRIBUTOR
 
 
 declare void @deref_phi_user(i32* %a);
 
 ; TEST 1
 ; take mininimum of return values
 ;
 define i32* @test1(i32* dereferenceable(4) %0, double* dereferenceable(8) %1, i1 zeroext %2) local_unnamed_addr {
-; ATTRIBUTOR: define nonnull dereferenceable(4) i32* @test1(i32* nonnull dereferenceable(4) %0, double* nonnull dereferenceable(8) %1, i1 zeroext %2)
+; ATTRIBUTOR: define nonnull dereferenceable(4) i32* @test1(i32* nonnull dereferenceable(4) "no-capture-maybe-returned" %0, double* nonnull dereferenceable(8) "no-capture-maybe-returned" %1, i1 zeroext %2)
   %4 = bitcast double* %1 to i32*
   %5 = select i1 %2, i32* %0, i32* %4
   ret i32* %5
 }
 
 ; TEST 2
 define i32* @test2(i32* dereferenceable_or_null(4) %0, double* dereferenceable(8) %1, i1 zeroext %2) local_unnamed_addr {
-; ATTRIBUTOR: define dereferenceable_or_null(4) i32* @test2(i32* dereferenceable_or_null(4) %0, double* nonnull dereferenceable(8) %1, i1 zeroext %2)
+; ATTRIBUTOR: define dereferenceable_or_null(4) i32* @test2(i32* dereferenceable_or_null(4) "no-capture-maybe-returned" %0, double* nonnull dereferenceable(8) "no-capture-maybe-returned" %1, i1 zeroext %2)
   %4 = bitcast double* %1 to i32*
   %5 = select i1 %2, i32* %0, i32* %4
   ret i32* %5
 }
 
 ; TEST 3
 ; GEP inbounds
 define i32* @test3_1(i32* dereferenceable(8) %0) local_unnamed_addr {
-; ATTRIBUTOR: define nonnull dereferenceable(4) i32* @test3_1(i32* nonnull dereferenceable(8) %0)
+; ATTRIBUTOR: define nonnull dereferenceable(4) i32* @test3_1(i32* nonnull dereferenceable(8) "no-capture-maybe-returned" %0)
   %ret = getelementptr inbounds i32, i32* %0, i64 1
   ret i32* %ret
 }
 
 define i32* @test3_2(i32* dereferenceable_or_null(32) %0) local_unnamed_addr {
 ; FIXME: Argument should be mark dereferenceable because of GEP `inbounds`.
-; ATTRIBUTOR: define nonnull dereferenceable(16) i32* @test3_2(i32* dereferenceable_or_null(32) %0)
+; ATTRIBUTOR: define nonnull dereferenceable(16) i32* @test3_2(i32* dereferenceable_or_null(32) "no-capture-maybe-returned" %0)
   %ret = getelementptr inbounds i32, i32* %0, i64 4
   ret i32* %ret
 }
 
 define i32* @test3_3(i32* dereferenceable(8) %0, i32* dereferenceable(16) %1, i1 %2) local_unnamed_addr {
-; ATTRIBUTOR: define nonnull dereferenceable(4) i32* @test3_3(i32* nonnull dereferenceable(8) %0, i32* nonnull dereferenceable(16) %1, i1 %2) local_unnamed_addr
+; ATTRIBUTOR: define nonnull dereferenceable(4) i32* @test3_3(i32* nonnull dereferenceable(8) "no-capture-maybe-returned" %0, i32* nonnull dereferenceable(16) "no-capture-maybe-returned" %1, i1 %2) local_unnamed_addr
   %ret1 = getelementptr inbounds i32, i32* %0, i64 1
   %ret2 = getelementptr inbounds i32, i32* %1, i64 2
   %ret = select i1 %2, i32* %ret1, i32* %ret2
   ret i32* %ret
 }
 
 ; TEST 4
 ; Better than known in IR.
 
 define dereferenceable(4) i32* @test4(i32* dereferenceable(8) %0) local_unnamed_addr {
-; ATTRIBUTOR: define nonnull dereferenceable(8) i32* @test4(i32* nonnull returned dereferenceable(8) %0)
+; ATTRIBUTOR: define nonnull dereferenceable(8) i32* @test4(i32* nonnull returned dereferenceable(8) "no-capture-maybe-returned" %0)
   ret i32* %0
 }
 
 ; TEST 5
 ; loop in which dereferenceabily "grows"
 define void @deref_phi_growing(i32* dereferenceable(4000) %a) {
 entry:
   br label %for.cond

llvm/test/Transforms/FunctionAttrs/internal-noalias.ll

 ; RUN: opt -S -attributor -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=8 < %s | FileCheck %s
 
 define dso_local i32 @visible(i32* noalias %A, i32* noalias %B) #0 {
 entry:
   %call1 = call i32 @noalias_args(i32* %A, i32* %B)
   %call2 = call i32 @noalias_args_argmem(i32* %A, i32* %B)
   %add = add nsw i32 %call1, %call2
   ret i32 %add
 }
 
 ; FIXME: Should be something like this.
 ; define internal i32 @noalias_args(i32* nocapture readonly %A, i32* noalias nocapture readonly %B)
-; CHECK: define internal i32 @noalias_args(i32* %A, i32* %B)
+; CHECK: define internal i32 @noalias_args(i32* nocapture %A, i32* nocapture %B)
 
 define internal i32 @noalias_args(i32* %A, i32* %B) #0 {
 entry:
   %0 = load i32, i32* %A, align 4
   %1 = load i32, i32* %B, align 4
   %add = add nsw i32 %0, %1
   %call = call i32 @noalias_args_argmem(i32* %A, i32* %B)
   %add2 = add nsw i32 %add, %call
   ret i32 %add2
 }
 
 
 ; FIXME: Should be something like this.
 ; define internal i32 @noalias_args_argmem(i32* noalias nocapture readonly %A, i32* noalias nocapture readonly %B)
-; CHECK: define internal i32 @noalias_args_argmem(i32* %A, i32* %B)
+; CHECK: define internal i32 @noalias_args_argmem(i32* nocapture %A, i32* nocapture %B)
 ;
 define internal i32 @noalias_args_argmem(i32* %A, i32* %B) #1 {
 entry:
   %0 = load i32, i32* %A, align 4
   %1 = load i32, i32* %B, align 4
   %add = add nsw i32 %0, %1
   ret i32 %add
 }

llvm/test/Transforms/FunctionAttrs/liveness.ll

 
 ; CHECK: Function Attrs: nofree norecurse nounwind uwtable willreturn
 define i32 @volatile_load(i32*) norecurse nounwind uwtable {
   %2 = load volatile i32, i32* %0, align 4
   ret i32 %2
 }
 
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind uwtable willreturn
-; CHECK-NEXT: define internal i32 @internal_load(i32* nonnull %0)
+; CHECK-NEXT: define internal i32 @internal_load(i32* nocapture nonnull %0)
 define internal i32 @internal_load(i32*) norecurse nounwind uwtable {
   %2 = load i32, i32* %0, align 4
   ret i32 %2
 }
 ; TEST 1: Only first block is live.
 
 ; CHECK: Function Attrs: nofree noreturn nosync nounwind
-; CHECK-NEXT: define i32 @first_block_no_return(i32 %a, i32* nonnull %ptr1, i32* %ptr2)
+; CHECK-NEXT: define i32 @first_block_no_return(i32 %a, i32* nocapture nonnull %ptr1, i32* nocapture %ptr2)
 define i32 @first_block_no_return(i32 %a, i32* nonnull %ptr1, i32* %ptr2) #0 {
 entry:
   call i32 @internal_load(i32* %ptr1)
-  ; CHECK: call i32 @internal_load(i32* nonnull %ptr1)
+  ; CHECK: call i32 @internal_load(i32* nocapture nonnull %ptr1)
   call void @no_return_call()
   ; CHECK: call void @no_return_call()
   ; CHECK-NEXT: unreachable
   call i32 @dead_internal_func(i32 10)
   ; CHECK call i32 undef(i32 10)
   %cmp = icmp eq i32 %a, 0
   br i1 %cmp, label %cond.true, label %cond.false
 

 }
 
 ; TEST 2: cond.true is dead, but cond.end is not, since cond.false is live
 
 ; This is just an example. For example we can put a sync call in a
 ; dead block and check if it is deduced.
 
 ; CHECK: Function Attrs: nosync
-; CHECK-NEXT: define i32 @dead_block_present(i32 %a, i32* %ptr1)
+; CHECK-NEXT: define i32 @dead_block_present(i32 %a, i32* nocapture %ptr1)
 define i32 @dead_block_present(i32 %a, i32* %ptr1) #0 {
 entry:
   %cmp = icmp eq i32 %a, 0
   br i1 %cmp, label %cond.true, label %cond.false
 
 cond.true:                                        ; preds = %entry
   call void @no_return_call()
   ; CHECK: call void @no_return_call()
cleanup:
   %res = landingpad { i8*, i32 }
   catch i8* null
   ret i32 0
 }
 
 ; TEST 6: Undefined behvior, taken from LangRef.
 ; FIXME: Should be able to detect undefined behavior.
 
-; CHECK: define void @ub(i32* %0)
+; CHECK: define void @ub(i32* nocapture %0)
 define void @ub(i32* %0) {
   %poison = sub nuw i32 0, 1           ; Results in a poison value.
   %still_poison = and i32 %poison, 0   ; 0, but also poison.
   %poison_yet_again = getelementptr i32, i32* %0, i32 %still_poison
   store i32 0, i32* %poison_yet_again  ; Undefined behavior due to store to poison.
   ret void
 }
 

llvm/test/Transforms/FunctionAttrs/noalias_returned.ll

 ; call noalias function in return instruction.
 
 ; CHECK: define noalias i8* @return_noalias()
 define i8* @return_noalias(){
   %1 = tail call noalias i8* @malloc(i64 4)
   ret i8* %1
 }
 
+define void @nocapture(i8* %a){
+  ret void
+}
+
+; CHECK: define noalias i8* @return_noalias_looks_like_capture()
+define i8* @return_noalias_looks_like_capture(){
+  %1 = tail call noalias i8* @malloc(i64 4)
+  call void @nocapture(i8* %1)
+  ret i8* %1
+}
+
 declare i8* @alias()
 
 ; TEST 3
 ; CHECK: define i8* @call_alias()
 ; CHECK-NOT: noalias
 define i8* @call_alias(){
   %1 = tail call i8* @alias()
   ret i8* %1

 5:                                                ; preds = %1, %4
   ret i8* %2
 }
 
 ; TEST 9
 ; Simple Argument Test
 define internal void @test9(i8* %a, i8* %b) {
 ; FIXME: missing noalias
-; CHECK: define internal void @test9(i8* %a, i8* %b)
+; CHECK: define internal void @test9(i8* nocapture %a, i8* nocapture %b)
   ret void
 }
 define void @test9_helper(i8* %a, i8* %b) {
   tail call void @test9(i8* noalias %a, i8* %b)
   tail call void @test9(i8* noalias %b, i8* noalias %a)
   ret void
 }
 

llvm/test/Transforms/FunctionAttrs/nocapture.ll

-; RUN: opt < %s -functionattrs -S | FileCheck %s
-; RUN: opt < %s -passes=function-attrs -S | FileCheck %s
+; RUN: opt -functionattrs -S < %s | FileCheck %s --check-prefixes=FNATTR,EITHER
+; RUN: opt -passes=function-attrs -S < %s | FileCheck %s --check-prefixes=FNATTR,EITHER
+; RUN: opt -attributor -attributor-disable=false -S < %s | FileCheck %s --check-prefixes=ATTRIBUTOR,EITHER
+; RUN: opt -passes=attributor -attributor-disable=false -S < %s | FileCheck %s --check-prefixes=ATTRIBUTOR,EITHER
 
 @g = global i32* null   ; <i32**> [#uses=1]
 
-; CHECK: define i32* @c1(i32* readnone returned %q)
+; FNATTR: define i32* @c1(i32* readnone returned %q)
+; ATTRIBUTOR: define i32* @c1(i32* returned "no-capture-maybe-returned" %q)
 define i32* @c1(i32* %q) {
   ret i32* %q
 }
 
-; CHECK: define void @c2(i32* %q)
+; EITHER: define void @c2(i32* %q)
 ; It would also be acceptable to mark %q as readnone. Update @c3 too.
 define void @c2(i32* %q) {
   store i32* %q, i32** @g
   ret void
 }
 
-; CHECK: define void @c3(i32* %q)
+; EITHER: define void @c3(i32* %q)
 define void @c3(i32* %q) {
   call void @c2(i32* %q)
   ret void
 }
 
-; CHECK: define i1 @c4(i32* %q, i32 %bitno)
+; EITHER: define i1 @c4(i32* %q, i32 %bitno)
 define i1 @c4(i32* %q, i32 %bitno) {
   %tmp = ptrtoint i32* %q to i32
   %tmp2 = lshr i32 %tmp, %bitno
   %bit = trunc i32 %tmp2 to i1
   br i1 %bit, label %l1, label %l0
 l0:
   ret i1 0 ; escaping value not caught by def-use chaining.
 l1:
   ret i1 1 ; escaping value not caught by def-use chaining.
 }
 
 @lookup_table = global [2 x i1] [ i1 0, i1 1 ]
 
-; CHECK: define i1 @c5(i32* %q, i32 %bitno)
+; EITHER: define i1 @c5(i32* %q, i32 %bitno)
 define i1 @c5(i32* %q, i32 %bitno) {
   %tmp = ptrtoint i32* %q to i32
   %tmp2 = lshr i32 %tmp, %bitno
   %bit = and i32 %tmp2, 1
         ; subtle escape mechanism follows
   %lookup = getelementptr [2 x i1], [2 x i1]* @lookup_table, i32 0, i32 %bit
   %val = load i1, i1* %lookup
   ret i1 %val
 }
 
 declare void @throw_if_bit_set(i8*, i8) readonly
 
-; CHECK: define i1 @c6(i8* readonly %q, i8 %bit)
+; FNATTR: define i1 @c6(i8* readonly %q, i8 %bit)
+; ATTRIBUTOR: define i1 @c6(i8* %q, i8 %bit)
 define i1 @c6(i8* %q, i8 %bit) personality i32 (...)* @__gxx_personality_v0 {
   invoke void @throw_if_bit_set(i8* %q, i8 %bit)
     to label %ret0 unwind label %ret1
 ret0:
   ret i1 0
 ret1:
         %exn = landingpad {i8*, i32}
                  cleanup
   ret i1 1
 }
 
 declare i32 @__gxx_personality_v0(...)
 
 define i1* @lookup_bit(i32* %q, i32 %bitno) readnone nounwind {
   %tmp = ptrtoint i32* %q to i32
   %tmp2 = lshr i32 %tmp, %bitno
   %bit = and i32 %tmp2, 1
   %lookup = getelementptr [2 x i1], [2 x i1]* @lookup_table, i32 0, i32 %bit
   ret i1* %lookup
 }
 
-; CHECK: define i1 @c7(i32* readonly %q, i32 %bitno)
+; FNATTR: define i1 @c7(i32* readonly %q, i32 %bitno)
+; ATTRIBUTOR: define i1 @c7(i32* %q, i32 %bitno)
 define i1 @c7(i32* %q, i32 %bitno) {
   %ptr = call i1* @lookup_bit(i32* %q, i32 %bitno)
   %val = load i1, i1* %ptr
   ret i1 %val
 }
 
 
-; CHECK: define i32 @nc1(i32* %q, i32* nocapture %p, i1 %b)
+; EITHER: define i32 @nc1(i32* %q, i32* nocapture %p, i1 %b)
 define i32 @nc1(i32* %q, i32* %p, i1 %b) {
 e:
   br label %l
 l:
   %x = phi i32* [ %p, %e ]
   %y = phi i32* [ %q, %e ]
   %tmp = bitcast i32* %x to i32*    ; <i32*> [#uses=2]
   %tmp2 = select i1 %b, i32* %tmp, i32* %y
   %val = load i32, i32* %tmp2    ; <i32> [#uses=1]
   store i32 0, i32* %tmp
   store i32* %y, i32** @g
   ret i32 %val
 }
 
-; CHECK: define i32 @nc1_addrspace(i32* %q, i32 addrspace(1)* nocapture %p, i1 %b)
+; EITHER: define i32 @nc1_addrspace(i32* %q, i32 addrspace(1)* nocapture %p, i1 %b)
 define i32 @nc1_addrspace(i32* %q, i32 addrspace(1)* %p, i1 %b) {
 e:
   br label %l
 l:
   %x = phi i32 addrspace(1)* [ %p, %e ]
   %y = phi i32* [ %q, %e ]
   %tmp = addrspacecast i32 addrspace(1)* %x to i32*    ; <i32*> [#uses=2]
   %tmp2 = select i1 %b, i32* %tmp, i32* %y
   %val = load i32, i32* %tmp2    ; <i32> [#uses=1]
   store i32 0, i32* %tmp
   store i32* %y, i32** @g
   ret i32 %val
 }
 
-; CHECK: define void @nc2(i32* nocapture %p, i32* %q)
+; EITHER: define void @nc2(i32* nocapture %p, i32* %q)
 define void @nc2(i32* %p, i32* %q) {
   %1 = call i32 @nc1(i32* %q, i32* %p, i1 0)    ; <i32> [#uses=0]
   ret void
 }
 
-; CHECK: define void @nc3(void ()* nocapture %p)
+; EITHER: define void @nc3(void ()* nocapture %p)
 define void @nc3(void ()* %p) {
   call void %p()
   ret void
 }
 
 declare void @external(i8*) readonly nounwind
-; CHECK: define void @nc4(i8* nocapture readonly %p)
+; FNATTR: define void @nc4(i8* nocapture readonly %p)
+; ATTRIBUTOR: define void @nc4(i8* nocapture %p)
 define void @nc4(i8* %p) {
   call void @external(i8* %p)
   ret void
 }
 
-; CHECK: define void @nc5(void (i8*)* nocapture %f, i8* nocapture %p)
+; EITHER: define void @nc5(void (i8*)* nocapture %f, i8* nocapture %p)
 define void @nc5(void (i8*)* %f, i8* %p) {
   call void %f(i8* %p) readonly nounwind
   call void %f(i8* nocapture %p)
   ret void
 }
 
-; CHECK: define void @test1_1(i8* nocapture readnone %x1_1, i8* %y1_1)
+; FNATTR:     define void @test1_1(i8* nocapture readnone %x1_1, i8* %y1_1, i1 %c)
+; ATTRIBUTOR: define void @test1_1(i8* nocapture %x1_1, i8* nocapture %y1_1, i1 %c)
 ; It would be acceptable to add readnone to %y1_1 and %y1_2.
-define void @test1_1(i8* %x1_1, i8* %y1_1) {
-  call i8* @test1_2(i8* %x1_1, i8* %y1_1)
+define void @test1_1(i8* %x1_1, i8* %y1_1, i1 %c) {
+  call i8* @test1_2(i8* %x1_1, i8* %y1_1, i1 %c)
   store i32* null, i32** @g
   ret void
 }
 
-; CHECK: define i8* @test1_2(i8* nocapture readnone %x1_2, i8* returned %y1_2)
-define i8* @test1_2(i8* %x1_2, i8* %y1_2) {
-  call void @test1_1(i8* %x1_2, i8* %y1_2)
+; FNATTR: define i8* @test1_2(i8* nocapture readnone %x1_2, i8* returned %y1_2, i1 %c)
+; ATTRIBUTOR: define i8* @test1_2(i8* nocapture %x1_2, i8* returned "no-capture-maybe-returned" %y1_2, i1 %c)
+define i8* @test1_2(i8* %x1_2, i8* %y1_2, i1 %c) {
+  br i1 %c, label %t, label %f
+t:
+  call void @test1_1(i8* %x1_2, i8* %y1_2, i1 %c)
   store i32* null, i32** @g
+  br label %f
+f:
   ret i8* %y1_2
 }
 
-; CHECK: define void @test2(i8* nocapture readnone %x2)
+; FNATTR: define void @test2(i8* nocapture readnone %x2)
+; ATTRIBUTOR: define void @test2(i8* nocapture %x2)
 define void @test2(i8* %x2) {
   call void @test2(i8* %x2)
   store i32* null, i32** @g
   ret void
 }
 
-; CHECK: define void @test3(i8* nocapture readnone %x3, i8* nocapture readnone %y3, i8* nocapture readnone %z3)
+; FNATTR: define void @test3(i8* nocapture readnone %x3, i8* nocapture readnone %y3, i8* nocapture readnone %z3)
+; ATTRIBUTOR: define void @test3(i8* nocapture %x3, i8* nocapture %y3, i8* nocapture %z3)
 define void @test3(i8* %x3, i8* %y3, i8* %z3) {
   call void @test3(i8* %z3, i8* %y3, i8* %x3)
   store i32* null, i32** @g
   ret void
 }
 
-; CHECK: define void @test4_1(i8* %x4_1)
-define void @test4_1(i8* %x4_1) {
-  call i8* @test4_2(i8* %x4_1, i8* %x4_1, i8* %x4_1)
+; FNATTR: define void @test4_1(i8* %x4_1, i1 %c)
+; ATTRIBUTOR: define void @test4_1(i8* nocapture %x4_1, i1 %c)
+define void @test4_1(i8* %x4_1, i1 %c) {
+  call i8* @test4_2(i8* %x4_1, i8* %x4_1, i8* %x4_1, i1 %c)
   store i32* null, i32** @g
   ret void
 }
 
-; CHECK: define i8* @test4_2(i8* nocapture readnone %x4_2, i8* readnone returned %y4_2, i8* nocapture readnone %z4_2)
-define i8* @test4_2(i8* %x4_2, i8* %y4_2, i8* %z4_2) {
-  call void @test4_1(i8* null)
+; FNATTR: define i8* @test4_2(i8* nocapture readnone %x4_2, i8* readnone returned %y4_2, i8* nocapture readnone %z4_2, i1 %c)
+; ATTRIBUTOR: define i8* @test4_2(i8* nocapture %x4_2, i8* returned "no-capture-maybe-returned" %y4_2, i8* nocapture %z4_2, i1 %c)
+define i8* @test4_2(i8* %x4_2, i8* %y4_2, i8* %z4_2, i1 %c) {
+  br i1 %c, label %t, label %f
+t:
+  call void @test4_1(i8* null, i1 %c)
   store i32* null, i32** @g
+  br label %f
+f:
   ret i8* %y4_2
 }
 
 declare i8* @test5_1(i8* %x5_1)
 
-; CHECK: define void @test5_2(i8* %x5_2)
+; EITHER: define void @test5_2(i8* %x5_2)
 define void @test5_2(i8* %x5_2) {
   call i8* @test5_1(i8* %x5_2)
   store i32* null, i32** @g
   ret void
 }
 
 declare void @test6_1(i8* %x6_1, i8* nocapture %y6_1, ...)
 
-; CHECK: define void @test6_2(i8* %x6_2, i8* nocapture %y6_2, i8* %z6_2)
+; EITHER: define void @test6_2(i8* %x6_2, i8* nocapture %y6_2, i8* %z6_2)
 define void @test6_2(i8* %x6_2, i8* %y6_2, i8* %z6_2) {
   call void (i8*, i8*, ...) @test6_1(i8* %x6_2, i8* %y6_2, i8* %z6_2)
   store i32* null, i32** @g
   ret void
 }
 
-; CHECK: define void @test_cmpxchg(i32* nocapture %p)
+; EITHER: define void @test_cmpxchg(i32* nocapture %p)
 define void @test_cmpxchg(i32* %p) {
   cmpxchg i32* %p, i32 0, i32 1 acquire monotonic
   ret void
 }
 
-; CHECK: define void @test_cmpxchg_ptr(i32** nocapture %p, i32* %q)
+; EITHER: define void @test_cmpxchg_ptr(i32** nocapture %p, i32* %q)
 define void @test_cmpxchg_ptr(i32** %p, i32* %q) {
   cmpxchg i32** %p, i32* null, i32* %q acquire monotonic
   ret void
 }
 
-; CHECK: define void @test_atomicrmw(i32* nocapture %p)
+; EITHER: define void @test_atomicrmw(i32* nocapture %p)
 define void @test_atomicrmw(i32* %p) {
   atomicrmw add i32* %p, i32 1 seq_cst
   ret void
 }
 
-; CHECK: define void @test_volatile(i32* %x)
+; EITHER: define void @test_volatile(i32* %x)
 define void @test_volatile(i32* %x) {
 entry:
   %gep = getelementptr i32, i32* %x, i64 1
   store volatile i32 0, i32* %gep, align 4
   ret void
 }
 
-; CHECK: nocaptureLaunder(i8* nocapture %p)
+; EITHER: nocaptureLaunder(i8* nocapture %p)
 define void @nocaptureLaunder(i8* %p) {
 entry:
   %b = call i8* @llvm.launder.invariant.group.p0i8(i8* %p)
   store i8 42, i8* %b
   ret void
 }
 
 @g2 = global i8* null
-; CHECK: define void @captureLaunder(i8* %p)
+; EITHER: define void @captureLaunder(i8* %p)
 define void @captureLaunder(i8* %p) {
   %b = call i8* @llvm.launder.invariant.group.p0i8(i8* %p)
   store i8* %b, i8** @g2
   ret void
 }
 
-; CHECK: @nocaptureStrip(i8* nocapture %p)
+; EITHER: @nocaptureStrip(i8* nocapture %p)
 define void @nocaptureStrip(i8* %p) {
 entry:
   %b = call i8* @llvm.strip.invariant.group.p0i8(i8* %p)
   store i8 42, i8* %b
   ret void
 }
 
 @g3 = global i8* null
-; CHECK: define void @captureStrip(i8* %p)
+; EITHER: define void @captureStrip(i8* %p)
 define void @captureStrip(i8* %p) {
   %b = call i8* @llvm.strip.invariant.group.p0i8(i8* %p)
   store i8* %b, i8** @g3
   ret void
 }
 
-; CHECK: define i1 @captureICmp(i32* readnone %x)
+; FNATTR: define i1 @captureICmp(i32* readnone %x)
+; ATTRIBUTOR: define i1 @captureICmp(i32* %x)
 define i1 @captureICmp(i32* %x) {
   %1 = icmp eq i32* %x, null
   ret i1 %1
 }
 
-; CHECK: define i1 @captureICmpRev(i32* readnone %x)
+; FNATTR: define i1 @captureICmpRev(i32* readnone %x)
+; ATTRIBUTOR: define i1 @captureICmpRev(i32* %x)
 define i1 @captureICmpRev(i32* %x) {
   %1 = icmp eq i32* null, %x
   ret i1 %1
 }
 
-; CHECK: define i1 @nocaptureInboundsGEPICmp(i32* nocapture readnone %x)
+; FNATTR: define i1 @nocaptureInboundsGEPICmp(i32* nocapture readnone %x)
+; ATTRIBUTOR: define i1 @nocaptureInboundsGEPICmp(i32* nocapture %x)
 define i1 @nocaptureInboundsGEPICmp(i32* %x) {
   %1 = getelementptr inbounds i32, i32* %x, i32 5
   %2 = bitcast i32* %1 to i8*
   %3 = icmp eq i8* %2, null
   ret i1 %3
 }
 
-; CHECK: define i1 @nocaptureInboundsGEPICmpRev(i32* nocapture readnone %x)
+; FNATTR: define i1 @nocaptureInboundsGEPICmpRev(i32* nocapture readnone %x)
+; ATTRIBUTOR: define i1 @nocaptureInboundsGEPICmpRev(i32* nocapture %x)
 define i1 @nocaptureInboundsGEPICmpRev(i32* %x) {
   %1 = getelementptr inbounds i32, i32* %x, i32 5
   %2 = bitcast i32* %1 to i8*
   %3 = icmp eq i8* null, %2
   ret i1 %3
 }
 
-; CHECK: define i1 @nocaptureDereferenceableOrNullICmp(i32* nocapture readnone dereferenceable_or_null(4) %x)
+; FNATTR: define i1 @nocaptureDereferenceableOrNullICmp(i32* nocapture readnone dereferenceable_or_null(4) %x)
+; ATTRIBUTOR: define i1 @nocaptureDereferenceableOrNullICmp(i32* nocapture dereferenceable_or_null(4) %x)
 define i1 @nocaptureDereferenceableOrNullICmp(i32* dereferenceable_or_null(4) %x) {
   %1 = bitcast i32* %x to i8*
   %2 = icmp eq i8* %1, null
   ret i1 %2
 }
 
-; CHECK: define i1 @captureDereferenceableOrNullICmp(i32* readnone dereferenceable_or_null(4) %x)
+; FNATTR: define i1 @captureDereferenceableOrNullICmp(i32* readnone dereferenceable_or_null(4) %x)
+; ATTRIBUTOR: define i1 @captureDereferenceableOrNullICmp(i32* dereferenceable_or_null(4) %x)
 define i1 @captureDereferenceableOrNullICmp(i32* dereferenceable_or_null(4) %x) "null-pointer-is-valid"="true" {
   %1 = bitcast i32* %x to i8*
   %2 = icmp eq i8* %1, null
   ret i1 %2
 }
 
 declare i8* @llvm.launder.invariant.group.p0i8(i8*)
 declare i8* @llvm.strip.invariant.group.p0i8(i8*)

llvm/test/Transforms/FunctionAttrs/nonnull.ll

 define void @test13_helper() {
   %nonnullptr = tail call i8* @ret_nonnull()
   %maybenullptr = tail call i8* @unknown()
   tail call void @test13(i8* %nonnullptr, i8* %nonnullptr, i8* %maybenullptr)
   tail call void @test13(i8* %nonnullptr, i8* %maybenullptr, i8* %nonnullptr)
   ret void
 }
 define internal void @test13(i8* %a, i8* %b, i8* %c) {
-; ATTRIBUTOR: define internal void @test13(i8* nonnull %a, i8* %b, i8* %c) 
+; ATTRIBUTOR: define internal void @test13(i8* nocapture nonnull %a, i8* nocapture %b, i8* nocapture %c) 
   ret void
 }
 
 declare nonnull i8* @nonnull()
 
 ; TEST 14
 ; Complex propagation
 ; Argument of f1, f2, f3 can be marked with nonnull.

 
 ; Make sure that an invoke works similarly to a call.
 
 declare i32 @esfp(...)
 
 define i1 @parent8(i8* %a, i8* %bogus1, i8* %b) personality i8* bitcast (i32 (...)* @esfp to i8*){
 ; FNATTR-LABEL: @parent8(i8* nonnull %a, i8* nocapture readnone %bogus1, i8* nonnull %b)
 ; FIXME : missing "nonnull", it should be @parent8(i8* nonnull %a, i8* %bogus1, i8* nonnull %b)
-; ATTRIBUTOR-LABEL: @parent8(i8* %a, i8* %bogus1, i8* %b)
+; ATTRIBUTOR-LABEL: @parent8(i8* %a, i8* nocapture %bogus1, i8* %b)
 ; BOTH-NEXT:  entry:
 ; FNATTR-NEXT:    invoke void @use2nonnull(i8* %a, i8* %b)
 ; ATTRIBUTOR-NEXT:    invoke void @use2nonnull(i8* nonnull %a, i8* nonnull %b)
 ; BOTH-NEXT:    to label %cont unwind label %exc
 ; BOTH:       cont:
 ; BOTH-NEXT:    [[NULL_CHECK:%.*]] = icmp eq i8* %b, null
 ; BOTH-NEXT:    ret i1 [[NULL_CHECK]]
 ; BOTH:       exc:

llvm/test/Transforms/FunctionAttrs/nosync.ll

 ; TEST 1
 ; non-convergent and readnone implies nosync
 %struct.RT = type { i8, [10 x [20 x i32]], i8 }
 %struct.ST = type { i32, double, %struct.RT }
 
 ; FNATTR: Function Attrs: norecurse nounwind optsize readnone ssp uwtable
 ; FNATTR-NEXT: define nonnull i32* @foo(%struct.ST* readnone %s)
 ; ATTRIBUTOR: Function Attrs: nofree nosync nounwind optsize readnone ssp uwtable
-; ATTRIBUTOR-NEXT: define nonnull i32* @foo(%struct.ST* %s)
+; ATTRIBUTOR-NEXT: define nonnull i32* @foo(%struct.ST* "no-capture-maybe-returned" %s)
 define i32* @foo(%struct.ST* %s) nounwind uwtable readnone optsize ssp {
 entry:
   %arrayidx = getelementptr inbounds %struct.ST, %struct.ST* %s, i64 1, i32 2, i32 1, i64 5, i64 13
   ret i32* %arrayidx
 }
 
 ; TEST 2
 ; atomic load with monotonic ordering

 }
 
 ; TEST 11 - positive, should deduce nosync
 ; volatile operation in same scc but dead. Call volatile_load defined in TEST 8.
 
 ; FNATTR: Function Attrs: nofree noinline nounwind uwtable
 ; FNATTR-NEXT: define i32 @scc1(i32* %0)
 ; ATTRIBUTOR: Function Attrs: nofree noinline noreturn nosync nounwind uwtable
-; ATTRIBUTOR-NEXT: define i32 @scc1(i32* %0)
+; ATTRIBUTOR-NEXT: define i32 @scc1(i32* nocapture %0)
 define i32 @scc1(i32* %0) noinline nounwind uwtable {
   tail call void @scc2(i32* %0);
   %val = tail call i32 @volatile_load(i32* %0);
   ret i32 %val;
 }
 
 ; FNATTR: Function Attrs: nofree noinline nounwind uwtable
 ; FNATTR-NEXT: define void @scc2(i32* %0)
 ; ATTRIBUTOR: Function Attrs: nofree noinline noreturn nosync nounwind uwtable
-; ATTRIBUTOR-NEXT: define void @scc2(i32* %0)
+; ATTRIBUTOR-NEXT: define void @scc2(i32* nocapture %0)
 define void @scc2(i32* %0) noinline nounwind uwtable {
   tail call i32 @scc1(i32* %0);
   ret void;
 }
 
 ; TEST 12 - fences, negative
 ;
 ; void foo1(int *a, std::atomic<bool> flag){

 ; }
 
 %"struct.std::atomic" = type { %"struct.std::__atomic_base" }
 %"struct.std::__atomic_base" = type { i8 }
 
 ; FNATTR: Function Attrs: nofree norecurse nounwind
 ; FNATTR-NEXT: define void @foo1(i32* nocapture %0, %"struct.std::atomic"* nocapture %1)
 ; ATTRIBUTOR-NOT: nosync
-; ATTRIBUTOR: define void @foo1(i32* %0, %"struct.std::atomic"* %1)
+; ATTRIBUTOR: define void @foo1(i32* nocapture %0, %"struct.std::atomic"* nocapture %1)
 define void @foo1(i32* %0, %"struct.std::atomic"* %1) {
   store i32 100, i32* %0, align 4
   fence release
   %3 = getelementptr inbounds %"struct.std::atomic", %"struct.std::atomic"* %1, i64 0, i32 0, i32 0
   store atomic i8 1, i8* %3 monotonic, align 1
   ret void
 }
 
 ; FNATTR: Function Attrs: nofree norecurse nounwind
 ; FNATTR-NEXT: define void @bar(i32* nocapture readnone %0, %"struct.std::atomic"* nocapture readonly %1)
 ; ATTRIBUTOR-NOT: nosync
-; ATTRIBUTOR: define void @bar(i32* %0, %"struct.std::atomic"* %1)
+; ATTRIBUTOR: define void @bar(i32* nocapture %0, %"struct.std::atomic"* nocapture %1)
 define void @bar(i32* %0, %"struct.std::atomic"* %1) {
   %3 = getelementptr inbounds %"struct.std::atomic", %"struct.std::atomic"* %1, i64 0, i32 0, i32 0
   br label %4
 
 4:                                                ; preds = %4, %2
   %5 = load atomic i8, i8* %3  monotonic, align 1
   %6 = and i8 %5, 1
   %7 = icmp eq i8 %6, 0
   br i1 %7, label %4, label %8
 
 8:                                                ; preds = %4
   fence acquire
   ret void
 }
 
 ; TEST 13 - Fence syncscope("singlethread") seq_cst
 ; FNATTR: Function Attrs: nofree norecurse nounwind
 ; FNATTR-NEXT: define void @foo1_singlethread(i32* nocapture %0, %"struct.std::atomic"* nocapture %1)
 ; ATTRIBUTOR: Function Attrs: nofree nosync
-; ATTRIBUTOR: define void @foo1_singlethread(i32* %0, %"struct.std::atomic"* %1)
+; ATTRIBUTOR: define void @foo1_singlethread(i32* nocapture %0, %"struct.std::atomic"* nocapture %1)
 define void @foo1_singlethread(i32* %0, %"struct.std::atomic"* %1) {
   store i32 100, i32* %0, align 4
   fence syncscope("singlethread") release
   %3 = getelementptr inbounds %"struct.std::atomic", %"struct.std::atomic"* %1, i64 0, i32 0, i32 0
   store atomic i8 1, i8* %3 monotonic, align 1
   ret void
 }
 
 ; FNATTR: Function Attrs: nofree norecurse nounwind
 ; FNATTR-NEXT: define void @bar_singlethread(i32* nocapture readnone %0, %"struct.std::atomic"* nocapture readonly %1)
 ; ATTRIBUTOR: Function Attrs: nofree nosync
-; ATTRIBUTOR: define void @bar_singlethread(i32* %0, %"struct.std::atomic"* %1)
+; ATTRIBUTOR: define void @bar_singlethread(i32* nocapture %0, %"struct.std::atomic"* nocapture %1)
 define void @bar_singlethread(i32* %0, %"struct.std::atomic"* %1) {
   %3 = getelementptr inbounds %"struct.std::atomic", %"struct.std::atomic"* %1, i64 0, i32 0, i32 0
   br label %4
 
 4:                                                ; preds = %4, %2
   %5 = load atomic i8, i8* %3  monotonic, align 1
   %6 = and i8 %5, 1
   %7 = icmp eq i8 %6, 0
   br i1 %7, label %4, label %8
 
 8:                                                ; preds = %4
   fence syncscope("singlethread") acquire
   ret void
 }
 
 declare void @llvm.memcpy(i8* %dest, i8* %src, i32 %len, i1 %isvolatile)
 declare void @llvm.memset(i8* %dest, i8 %val, i32 %len, i1 %isvolatile)
 
 ; TEST 14 - negative, checking volatile intrinsics.
 
+; It is odd to add nocapture but a result of the llvm.memcpy nocapture.
+;
 ; ATTRIBUTOR: Function Attrs: nounwind
 ; ATTRIBUTOR-NOT: nosync
-; ATTRIBUTOR-NEXT: define i32 @memcpy_volatile(i8* %ptr1, i8* %ptr2)
+; ATTRIBUTOR-NEXT: define i32 @memcpy_volatile(i8* nocapture %ptr1, i8* nocapture %ptr2)
 define i32 @memcpy_volatile(i8* %ptr1, i8* %ptr2) {
   call void @llvm.memcpy(i8* %ptr1, i8* %ptr2, i32 8, i1 1)
   ret i32 4
 }
 
 ; TEST 15 - positive, non-volatile intrinsic.
 
+; It is odd to add nocapture but a result of the llvm.memset nocapture.
+;
 ; ATTRIBUTOR: Function Attrs: nosync
-; ATTRIBUTOR-NEXT: define i32 @memset_non_volatile(i8* %ptr1, i8 %val)
+; ATTRIBUTOR-NEXT: define i32 @memset_non_volatile(i8* nocapture %ptr1, i8 %val)
 define i32 @memset_non_volatile(i8* %ptr1, i8 %val) {
   call void @llvm.memset(i8* %ptr1, i8 %val, i32 8, i1 0)
   ret i32 4
 }
 
 ; TEST 16 - negative, inline assembly.
 
 ; ATTRIBUTOR: define i32 @inline_asm_test(i32 %x)

llvm/test/Transforms/FunctionAttrs/read_write_returned_arguments_scc.ll

if.end:                                           ; preds = %entry
   br label %return
 
 return:                                           ; preds = %if.end, %if.then
   %retval.0 = phi i32* [ %call8, %if.end ], [ %r1, %if.then ]
   ret i32* %retval.0
 }
 
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind
-; CHECK-NEXT: define i32* @external_sink_ret2_nrw(i32* readnone %n0, i32* nocapture readonly %r0, i32* returned %w0)
+; CHECK-NEXT: define i32* @external_sink_ret2_nrw(i32* readnone %n0, i32* nocapture readonly %r0, i32* returned "no-capture-maybe-returned" %w0)
 define i32* @external_sink_ret2_nrw(i32* %n0, i32* %r0, i32* %w0) {
 entry:
   %tobool = icmp ne i32* %n0, null
   br i1 %tobool, label %if.end, label %if.then
 
 if.then:                                          ; preds = %entry
   br label %return