C++ MDNode::replaceOperandWith方法代码示例

      void setUnrollID(Loop *L, bool enable) {
        if (!enable && disabledLoops.find(L) != disabledLoops.end())
           return;
        LLVMContext &Context = L->getHeader()->getContext();
#if LLVM_VERSION_MAJOR == 3 && LLVM_VERSION_MINOR >= 6
        SmallVector<Metadata *, 2> forceUnroll;
        forceUnroll.push_back(MDString::get(Context, "llvm.loop.unroll.enable"));
        forceUnroll.push_back(ConstantAsMetadata::get(ConstantInt::get(Type::getInt1Ty(Context), enable)));
        MDNode *forceUnrollNode = MDNode::get(Context, forceUnroll);
        SmallVector<Metadata *, 4> Vals;
        Vals.push_back(NULL);
        Vals.push_back(forceUnrollNode);
#else
        SmallVector<Value *, 2> forceUnroll;
        forceUnroll.push_back(MDString::get(Context, "llvm.loop.unroll.enable"));
        forceUnroll.push_back(ConstantInt::get(Type::getInt1Ty(Context), enable));
        MDNode *forceUnrollNode = MDNode::get(Context, forceUnroll);
        SmallVector<Value *, 4> Vals;
        Vals.push_back(NULL);
        Vals.push_back(forceUnrollNode);
#endif
        MDNode *NewLoopID = MDNode::get(Context, Vals);
        // Set operand 0 to refer to the loop id itself.
        NewLoopID->replaceOperandWith(0, NewLoopID);
        L->setLoopID(NewLoopID);
        if (!enable)
          disabledLoops.insert(L);
      }

/// Remap the operands of an MDNode.
///
/// If \c Node is temporary, uniquing cycles are ignored.  If \c Node is
/// distinct, uniquing cycles are resolved as they're found.
///
/// \pre \c Node.isDistinct() or \c Node.isTemporary().
static bool remapOperands(MDNode &Node,
                          SmallVectorImpl<MDNode *> &DistinctWorklist,
                          ValueToValueMapTy &VM, RemapFlags Flags,
                          ValueMapTypeRemapper *TypeMapper,
                          ValueMaterializer *Materializer) {
  assert(!Node.isUniqued() && "Expected temporary or distinct node");
  const bool IsDistinct = Node.isDistinct();

  bool AnyChanged = false;
  for (unsigned I = 0, E = Node.getNumOperands(); I != E; ++I) {
    Metadata *Old = Node.getOperand(I);
    Metadata *New = mapMetadataOp(Old, DistinctWorklist, VM, Flags, TypeMapper,
                                  Materializer);
    if (Old != New) {
      AnyChanged = true;
      Node.replaceOperandWith(I, New);

      // Resolve uniquing cycles underneath distinct nodes on the fly so they
      // don't infect later operands.
      if (IsDistinct)
        resolveCycles(New);
    }
  }

  return AnyChanged;
}

static llvm::MDNode *stripDebugLocFromLoopID(llvm::MDNode *N) {
  assert(N->op_begin() != N->op_end() && "Missing self reference?");

  // if there is no debug location, we do not have to rewrite this MDNode.
  if (std::none_of(N->op_begin() + 1, N->op_end(), [](const MDOperand &Op) {
        return isa<DILocation>(Op.get());
      }))
    return N;

  // If there is only the debug location without any actual loop metadata, we
  // can remove the metadata.
  if (std::none_of(N->op_begin() + 1, N->op_end(), [](const MDOperand &Op) {
        return !isa<DILocation>(Op.get());
      }))
    return nullptr;

  SmallVector<Metadata *, 4> Args;
  // Reserve operand 0 for loop id self reference.
  auto TempNode = MDNode::getTemporary(N->getContext(), None);
  Args.push_back(TempNode.get());
  // Add all non-debug location operands back.
  for (auto Op = N->op_begin() + 1; Op != N->op_end(); Op++) {
    if (!isa<DILocation>(*Op))
      Args.push_back(*Op);
  }

  // Set the first operand to itself.
  MDNode *LoopID = MDNode::get(N->getContext(), Args);
  LoopID->replaceOperandWith(0, LoopID);
  return LoopID;
}

// Remove existing unroll metadata and add unroll disable metadata to
// indicate the loop has already been unrolled.  This prevents a loop
// from being unrolled more than is directed by a pragma if the loop
// unrolling pass is run more than once (which it generally is).
static void SetLoopAlreadyUnrolled(Loop *L) {
  MDNode *LoopID = L->getLoopID();
  if (!LoopID) return;

  // First remove any existing loop unrolling metadata.
  SmallVector<Metadata *, 4> MDs;
  // Reserve first location for self reference to the LoopID metadata node.
  MDs.push_back(nullptr);
  for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
    bool IsUnrollMetadata = false;
    MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i));
    if (MD) {
      const MDString *S = dyn_cast<MDString>(MD->getOperand(0));
      IsUnrollMetadata = S && S->getString().startswith("llvm.loop.unroll.");
    }
    if (!IsUnrollMetadata)
      MDs.push_back(LoopID->getOperand(i));
  }

  // Add unroll(disable) metadata to disable future unrolling.
  LLVMContext &Context = L->getHeader()->getContext();
  SmallVector<Metadata *, 1> DisableOperands;
  DisableOperands.push_back(MDString::get(Context, "llvm.loop.unroll.disable"));
  MDNode *DisableNode = MDNode::get(Context, DisableOperands);
  MDs.push_back(DisableNode);

  MDNode *NewLoopID = MDNode::get(Context, MDs);
  // Set operand 0 to refer to the loop id itself.
  NewLoopID->replaceOperandWith(0, NewLoopID);
  L->setLoopID(NewLoopID);
}

void DIDescriptor::replaceFunctionField(unsigned Elt, Function *F) {
  if (!DbgNode)
    return;

  if (Elt < DbgNode->getNumOperands()) {
    MDNode *Node = const_cast<MDNode *>(DbgNode);
    Node->replaceOperandWith(Elt, F ? ConstantAsMetadata::get(F) : nullptr);
  }
}

void DIDescriptor::replaceFunctionField(unsigned Elt, Function *F) {
  if (DbgNode == 0)
    return;

  if (Elt < DbgNode->getNumOperands()) {
    MDNode *Node = const_cast<MDNode*>(DbgNode);
    Node->replaceOperandWith(Elt, F);
  }
}

void MDNodeMapper::remapOperands(MDNode &N, OperandMapper mapOperand) {
  assert(!N.isUniqued() && "Expected distinct or temporary nodes");
  for (unsigned I = 0, E = N.getNumOperands(); I != E; ++I) {
    Metadata *Old = N.getOperand(I);
    Metadata *New = mapOperand(Old);

    if (Old != New)
      N.replaceOperandWith(I, New);
  }
}

static MDNode *createMetadata(LLVMContext &Ctx, const LoopAttributes &Attrs) {

  if (!Attrs.IsParallel && Attrs.VectorizerWidth == 0 &&
      Attrs.VectorizerUnroll == 0 &&
      Attrs.VectorizerEnable == LoopAttributes::VecUnspecified)
    return nullptr;

  SmallVector<Value *, 4> Args;
  // Reserve operand 0 for loop id self reference.
  MDNode *TempNode = MDNode::getTemporary(Ctx, None);
  Args.push_back(TempNode);

  // Setting vectorizer.width
  if (Attrs.VectorizerWidth > 0) {
    Value *Vals[] = { MDString::get(Ctx, "llvm.loop.vectorize.width"),
                      ConstantInt::get(Type::getInt32Ty(Ctx),
                                       Attrs.VectorizerWidth) };
    Args.push_back(MDNode::get(Ctx, Vals));
  }

  // Setting vectorizer.unroll
  if (Attrs.VectorizerUnroll > 0) {
    Value *Vals[] = { MDString::get(Ctx, "llvm.loop.interleave.count"),
                      ConstantInt::get(Type::getInt32Ty(Ctx),
                                       Attrs.VectorizerUnroll) };
    Args.push_back(MDNode::get(Ctx, Vals));
  }

  // Setting vectorizer.enable
  if (Attrs.VectorizerEnable != LoopAttributes::VecUnspecified) {
    Value *Vals[] = { MDString::get(Ctx, "llvm.loop.vectorize.enable"),
                      ConstantInt::get(Type::getInt1Ty(Ctx),
                                       (Attrs.VectorizerEnable ==
                                        LoopAttributes::VecEnable)) };
    Args.push_back(MDNode::get(Ctx, Vals));
  }

  MDNode *LoopID = MDNode::get(Ctx, Args);
  assert(LoopID->use_empty() && "LoopID should not be used");

  // Set the first operand to itself.
  LoopID->replaceOperandWith(0, LoopID);
  MDNode::deleteTemporary(TempNode);
  return LoopID;
}

void MDNodeMapper::remapOperands(const Data &D, MDNode &N) {
  for (unsigned I = 0, E = N.getNumOperands(); I != E; ++I) {
    Metadata *Old = N.getOperand(I);
    Metadata *New;
    if (Optional<Metadata *> MappedOp = getMappedOp(Old)){
      New = *MappedOp;
    } else {
      assert(!N.isDistinct() &&
             "Expected all nodes to be pre-mapped for distinct operands");
      MDNode &OldN = *cast<MDNode>(Old);
      assert(!OldN.isDistinct() && "Expected distinct nodes to be pre-mapped");
      New = &getFwdReference(D, OldN);
    }

    if (Old != New)
      N.replaceOperandWith(I, New);
  }
}

/// @brief Get a self referencing id metadata node.
///
/// The MDNode looks like this (if arg0/arg1 are not null):
///
///    '!n = metadata !{metadata !n, arg0, arg1}'
///
/// @return The self referencing id metadata node.
static MDNode *getID(LLVMContext &Ctx, Metadata *arg0 = nullptr,
                     Metadata *arg1 = nullptr) {
  MDNode *ID;
  SmallVector<Metadata *, 3> Args;
  // Use a temporary node to safely create a unique pointer for the first arg.
  auto TempNode = MDNode::getTemporary(Ctx, None);
  // Reserve operand 0 for loop id self reference.
  Args.push_back(TempNode.get());

  if (arg0)
    Args.push_back(arg0);
  if (arg1)
    Args.push_back(arg1);

  ID = MDNode::get(Ctx, Args);
  ID->replaceOperandWith(0, ID);
  return ID;
}

static MDNode *createMetadata(LLVMContext &Ctx, const LoopAttributes &Attrs) {

  if (!Attrs.IsParallel && Attrs.VectorizeWidth == 0 &&
      Attrs.InterleaveCount == 0 &&
      Attrs.VectorizeEnable == LoopAttributes::Unspecified)
    return nullptr;

  SmallVector<Metadata *, 4> Args;
  // Reserve operand 0 for loop id self reference.
  auto TempNode = MDNode::getTemporary(Ctx, None);
  Args.push_back(TempNode.get());

  // Setting vectorize.width
  if (Attrs.VectorizeWidth > 0) {
    Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.vectorize.width"),
                        ConstantAsMetadata::get(ConstantInt::get(
                            Type::getInt32Ty(Ctx), Attrs.VectorizeWidth))};
    Args.push_back(MDNode::get(Ctx, Vals));
  }

  // Setting interleave.count
  if (Attrs.InterleaveCount > 0) {
    Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.interleave.count"),
                        ConstantAsMetadata::get(ConstantInt::get(
                            Type::getInt32Ty(Ctx), Attrs.InterleaveCount))};
    Args.push_back(MDNode::get(Ctx, Vals));
  }

  // Setting vectorize.enable
  if (Attrs.VectorizeEnable != LoopAttributes::Unspecified) {
    Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.vectorize.enable"),
                        ConstantAsMetadata::get(ConstantInt::get(
                            Type::getInt1Ty(Ctx), (Attrs.VectorizeEnable ==
                                                   LoopAttributes::Enable)))};
    Args.push_back(MDNode::get(Ctx, Vals));
  }

  // Set the first operand to itself.
  MDNode *LoopID = MDNode::get(Ctx, Args);
  LoopID->replaceOperandWith(0, LoopID);
  return LoopID;
}

/// \brief Set input string into loop metadata by keeping other values intact.
void llvm::addStringMetadataToLoop(Loop *TheLoop, const char *MDString,
                                   unsigned V) {
  SmallVector<Metadata *, 4> MDs(1);
  // If the loop already has metadata, retain it.
  MDNode *LoopID = TheLoop->getLoopID();
  if (LoopID) {
    for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
      MDNode *Node = cast<MDNode>(LoopID->getOperand(i));
      MDs.push_back(Node);
    }
  }
  // Add new metadata.
  MDs.push_back(createStringMetadata(TheLoop, MDString, V));
  // Replace current metadata node with new one.
  LLVMContext &Context = TheLoop->getHeader()->getContext();
  MDNode *NewLoopID = MDNode::get(Context, MDs);
  // Set operand 0 to refer to the loop id itself.
  NewLoopID->replaceOperandWith(0, NewLoopID);
  TheLoop->setLoopID(NewLoopID);
}

/// Remap the operands of an MDNode.
static bool remapOperands(MDNode &Node,
                          SmallVectorImpl<MDNode *> &DistinctWorklist,
                          ValueToValueMapTy &VM, RemapFlags Flags,
                          ValueMapTypeRemapper *TypeMapper,
                          ValueMaterializer *Materializer) {
  assert(!Node.isUniqued() && "Expected temporary or distinct node");

  bool AnyChanged = false;
  for (unsigned I = 0, E = Node.getNumOperands(); I != E; ++I) {
    Metadata *Old = Node.getOperand(I);
    Metadata *New = mapMetadataOp(Old, DistinctWorklist, VM, Flags, TypeMapper,
                                  Materializer);
    if (Old != New) {
      AnyChanged = true;
      Node.replaceOperandWith(I, New);
    }
  }

  return AnyChanged;
}

MDNode *MDBuilder::createAnonymousAARoot(StringRef Name, MDNode *Extra) {
  // To ensure uniqueness the root node is self-referential.
  auto Dummy = MDNode::getTemporary(Context, None);

  SmallVector<Metadata *, 3> Args(1, Dummy.get());
  if (Extra)
    Args.push_back(Extra);
  if (!Name.empty())
    Args.push_back(createString(Name));
  MDNode *Root = MDNode::get(Context, Args);

  // At this point we have
  //   !0 = metadata !{}            <- dummy
  //   !1 = metadata !{metadata !0} <- root
  // Replace the dummy operand with the root node itself and delete the dummy.
  Root->replaceOperandWith(0, Root);

  // We now have
  //   !1 = metadata !{metadata !1} <- self-referential root
  return Root;
}

MDNode *llvm::makePostTransformationMetadata(LLVMContext &Context,
                                             MDNode *OrigLoopID,
                                             ArrayRef<StringRef> RemovePrefixes,
                                             ArrayRef<MDNode *> AddAttrs) {
  // First remove any existing loop metadata related to this transformation.
  SmallVector<Metadata *, 4> MDs;

  // Reserve first location for self reference to the LoopID metadata node.
  TempMDTuple TempNode = MDNode::getTemporary(Context, None);
  MDs.push_back(TempNode.get());

  // Remove metadata for the transformation that has been applied or that became
  // outdated.
  if (OrigLoopID) {
    for (unsigned i = 1, ie = OrigLoopID->getNumOperands(); i < ie; ++i) {
      bool IsVectorMetadata = false;
      Metadata *Op = OrigLoopID->getOperand(i);
      if (MDNode *MD = dyn_cast<MDNode>(Op)) {
        const MDString *S = dyn_cast<MDString>(MD->getOperand(0));
        if (S)
          IsVectorMetadata =
              llvm::any_of(RemovePrefixes, [S](StringRef Prefix) -> bool {
                return S->getString().startswith(Prefix);
              });
      }
      if (!IsVectorMetadata)
        MDs.push_back(Op);
    }
  }

  // Add metadata to avoid reapplying a transformation, such as
  // llvm.loop.unroll.disable and llvm.loop.isvectorized.
  MDs.append(AddAttrs.begin(), AddAttrs.end());

  MDNode *NewLoopID = MDNode::getDistinct(Context, MDs);
  // Replace the temporary node with a self-reference.
  NewLoopID->replaceOperandWith(0, NewLoopID);
  return NewLoopID;
}