C++ MDNode::getNumOperands方法代码示例

/// \brief Find string metadata for loop
///
/// If it has a value (e.g. {"llvm.distribute", 1} return the value as an
/// operand or null otherwise.  If the string metadata is not found return
/// Optional's not-a-value.
Optional<const MDOperand *> llvm::findStringMetadataForLoop(Loop *TheLoop,
                                                            StringRef Name) {
  MDNode *LoopID = TheLoop->getLoopID();
  // Return none if LoopID is false.
  if (!LoopID)
    return None;

  // First operand should refer to the loop id itself.
  assert(LoopID->getNumOperands() > 0 && "requires at least one operand");
  assert(LoopID->getOperand(0) == LoopID && "invalid loop id");

  // Iterate over LoopID operands and look for MDString Metadata
  for (unsigned i = 1, e = LoopID->getNumOperands(); i < e; ++i) {
    MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i));
    if (!MD)
      continue;
    MDString *S = dyn_cast<MDString>(MD->getOperand(0));
    if (!S)
      continue;
    // Return true if MDString holds expected MetaData.
    if (Name.equals(S->getString()))
      switch (MD->getNumOperands()) {
      case 1:
        return nullptr;
      case 2:
        return &MD->getOperand(1);
      default:
        llvm_unreachable("loop metadata has 0 or 1 operand");
      }
  }
  return None;
}

/// parseMetadata - Parse metadata from the module
void LTOModule::parseMetadata() {
  // Linker Options
  if (Metadata *Val = getModule().getModuleFlag("Linker Options")) {
    MDNode *LinkerOptions = cast<MDNode>(Val);
    for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
      MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
      for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
        MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
        // FIXME: Make StringSet::insert match Self-Associative Container
        // requirements, returning <iter,bool> rather than bool, and use that
        // here.
        StringRef Op =
            _linkeropt_strings.insert(MDOption->getString()).first->first();
        StringRef DepLibName = _target->getSubtargetImpl()
                                   ->getTargetLowering()
                                   ->getObjFileLowering()
                                   .getDepLibFromLinkerOpt(Op);
        if (!DepLibName.empty())
          _deplibs.push_back(DepLibName.data());
        else if (!Op.empty())
          _linkeropts.push_back(Op.data());
      }
    }
  }

  // Add other interesting metadata here.
}

/// parseMetadata - Parse metadata from the module
void LTOModule::parseMetadata() {
  raw_string_ostream OS(LinkerOpts);

  // Linker Options
  if (Metadata *Val = getModule().getModuleFlag("Linker Options")) {
    MDNode *LinkerOptions = cast<MDNode>(Val);
    for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
      MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
      for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
        MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
        OS << " " << MDOption->getString();
      }
    }
  }

  // Globals
  Mangler Mang;
  for (const NameAndAttributes &Sym : _symbols) {
    if (!Sym.symbol)
      continue;
    _target->getObjFileLowering()->emitLinkerFlagsForGlobal(OS, Sym.symbol,
                                                            Mang);
  }

  // Add other interesting metadata here.
}

void TargetLoweringObjectFileCOFF::
emitModuleFlags(MCStreamer &Streamer,
                ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
                Mangler &Mang, const TargetMachine &TM) const {
  MDNode *LinkerOptions = nullptr;

  // Look for the "Linker Options" flag, since it's the only one we support.
  for (ArrayRef<Module::ModuleFlagEntry>::iterator
       i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) {
    const Module::ModuleFlagEntry &MFE = *i;
    StringRef Key = MFE.Key->getString();
    Metadata *Val = MFE.Val;
    if (Key == "Linker Options") {
      LinkerOptions = cast<MDNode>(Val);
      break;
    }
  }
  if (!LinkerOptions)
    return;

  // Emit the linker options to the linker .drectve section.  According to the
  // spec, this section is a space-separated string containing flags for linker.
  const MCSection *Sec = getDrectveSection();
  Streamer.SwitchSection(Sec);
  for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
    MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
    for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
      MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
      // Lead with a space for consistency with our dllexport implementation.
      std::string Directive(" ");
      Directive.append(MDOption->getString());
      Streamer.EmitBytes(Directive);
    }
  }
}

// Propagate existing explicit probabilities from either profile data or
// 'expect' intrinsic processing.
bool BranchProbabilityAnalysis::calcMetadataWeights(BasicBlock *BB) {
  TerminatorInst *TI = BB->getTerminator();
  if (TI->getNumSuccessors() == 1)
    return false;
  if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
    return false;

  MDNode *WeightsNode = TI->getMetadata(LLVMContext::MD_prof);
  if (!WeightsNode)
    return false;

  // Ensure there are weights for all of the successors. Note that the first
  // operand to the metadata node is a name, not a weight.
  if (WeightsNode->getNumOperands() != TI->getNumSuccessors() + 1)
    return false;

  // Build up the final weights that will be used in a temporary buffer, but
  // don't add them until all weihts are present. Each weight value is clamped
  // to [1, getMaxWeightFor(BB)].
  uint32_t WeightLimit = getMaxWeightFor(BB);
  SmallVector<uint32_t, 2> Weights;
  Weights.reserve(TI->getNumSuccessors());
  for (unsigned i = 1, e = WeightsNode->getNumOperands(); i != e; ++i) {
    ConstantInt *Weight = dyn_cast<ConstantInt>(WeightsNode->getOperand(i));
    if (!Weight)
      return false;
    Weights.push_back(
      std::max<uint32_t>(1, Weight->getLimitedValue(WeightLimit)));
  }
  assert(Weights.size() == TI->getNumSuccessors() && "Checked above");
  for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
    BP->setEdgeWeight(BB, TI->getSuccessor(i), Weights[i]);

  return true;
}

MDNode *MDNode::getMostGenericTBAA(MDNode *A, MDNode *B) {
  if (!A || !B)
    return NULL;

  if (A == B)
    return A;

  SmallVector<MDNode *, 4> PathA;
  MDNode *T = A;
  while (T) {
    PathA.push_back(T);
    T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0;
  }

  SmallVector<MDNode *, 4> PathB;
  T = B;
  while (T) {
    PathB.push_back(T);
    T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0;
  }

  int IA = PathA.size() - 1;
  int IB = PathB.size() - 1;

  MDNode *Ret = 0;
  while (IA >= 0 && IB >=0) {
    if (PathA[IA] == PathB[IB])
      Ret = PathA[IA];
    else
      break;
    --IA;
    --IB;
  }
  return Ret;
}

MDNode *MDNode::getMostGenericTBAA(MDNode *A, MDNode *B) {
  if (!A || !B)
    return nullptr;

  if (A == B)
    return A;

  // For struct-path aware TBAA, we use the access type of the tag.
  bool StructPath = isStructPathTBAA(A) && isStructPathTBAA(B);
  if (StructPath) {
    A = cast_or_null<MDNode>(A->getOperand(1));
    if (!A) return nullptr;
    B = cast_or_null<MDNode>(B->getOperand(1));
    if (!B) return nullptr;
  }

  SmallSetVector<MDNode *, 4> PathA;
  MDNode *T = A;
  while (T) {
    if (PathA.count(T))
      report_fatal_error("Cycle found in TBAA metadata.");
    PathA.insert(T);
    T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1))
                                 : nullptr;
  }

  SmallSetVector<MDNode *, 4> PathB;
  T = B;
  while (T) {
    if (PathB.count(T))
      report_fatal_error("Cycle found in TBAA metadata.");
    PathB.insert(T);
    T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1))
                                 : nullptr;
  }

  int IA = PathA.size() - 1;
  int IB = PathB.size() - 1;

  MDNode *Ret = nullptr;
  while (IA >= 0 && IB >=0) {
    if (PathA[IA] == PathB[IB])
      Ret = PathA[IA];
    else
      break;
    --IA;
    --IB;
  }
  if (!StructPath)
    return Ret;

  if (!Ret)
    return nullptr;
  // We need to convert from a type node to a tag node.
  Type *Int64 = IntegerType::get(A->getContext(), 64);
  Metadata *Ops[3] = {Ret, Ret,
                      ConstantAsMetadata::get(ConstantInt::get(Int64, 0))};
  return MDNode::get(A->getContext(), Ops);
}

// Propagate existing explicit probabilities from either profile data or
// 'expect' intrinsic processing.
bool BranchProbabilityInfo::calcMetadataWeights(BasicBlock *BB) {
    TerminatorInst *TI = BB->getTerminator();
    if (TI->getNumSuccessors() == 1)
        return false;
    if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
        return false;

    MDNode *WeightsNode = TI->getMetadata(LLVMContext::MD_prof);
    if (!WeightsNode)
        return false;

    // Check that the number of successors is manageable.
    assert(TI->getNumSuccessors() < UINT32_MAX && "Too many successors");

    // Ensure there are weights for all of the successors. Note that the first
    // operand to the metadata node is a name, not a weight.
    if (WeightsNode->getNumOperands() != TI->getNumSuccessors() + 1)
        return false;

    // Build up the final weights that will be used in a temporary buffer.
    // Compute the sum of all weights to later decide whether they need to
    // be scaled to fit in 32 bits.
    uint64_t WeightSum = 0;
    SmallVector<uint32_t, 2> Weights;
    Weights.reserve(TI->getNumSuccessors());
    for (unsigned i = 1, e = WeightsNode->getNumOperands(); i != e; ++i) {
        ConstantInt *Weight =
            mdconst::dyn_extract<ConstantInt>(WeightsNode->getOperand(i));
        if (!Weight)
            return false;
        assert(Weight->getValue().getActiveBits() <= 32 &&
               "Too many bits for uint32_t");
        Weights.push_back(Weight->getZExtValue());
        WeightSum += Weights.back();
    }
    assert(Weights.size() == TI->getNumSuccessors() && "Checked above");

    // If the sum of weights does not fit in 32 bits, scale every weight down
    // accordingly.
    uint64_t ScalingFactor =
        (WeightSum > UINT32_MAX) ? WeightSum / UINT32_MAX + 1 : 1;

    WeightSum = 0;
    for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
        uint32_t W = Weights[i] / ScalingFactor;
        WeightSum += W;
        setEdgeWeight(BB, i, W);
    }
    assert(WeightSum <= UINT32_MAX &&
           "Expected weights to scale down to 32 bits");

    return true;
}

  void
  SpecializationTable::initialize(Module* m)
  {
    assert(this->module == NULL);
    this->module = m;
#ifdef RECORD_IN_METADATA
    // Parse the module metadata to populate the table
    NamedMDNode* specs = m->getNamedMetadata("previrt::specializations");
    if (specs == NULL)
    return;

    errs() << "Specialization Count: " << specs->getNumOperands() << "\n";

    for (unsigned int i = 0; i < specs->getNumOperands(); ++i) {
      MDNode* funNode = specs->getOperand(i);
      if (funNode == NULL) {
        continue;
      }
      assert (funNode->getNumOperands() > 2);
      MDString* prinName = dyn_cast_or_null<MDString>(funNode->getOperand(0));
      MDString* specName = dyn_cast_or_null<MDString>(funNode->getOperand(1));
      if (prinName == NULL || specName == NULL) {
        errs() << "must skip " << (prinName == NULL ? "?" : prinName->getString()) << "\n";
        continue;
      }
      Function* prin = m->getFunction(prinName->getString());
      Function* spec = m->getFunction(specName->getString());
      if (prin == NULL || spec == NULL) {
        errs() << "must skip " << (prin == NULL ? "?" : prin->getName()) << "\n";
        continue;
      }

      const unsigned int arg_count = prin->getArgumentList().size();
      if (funNode->getNumOperands() != 2 + arg_count) {
        continue;
      }

      SpecScheme scheme = new Value*[arg_count];
      for (unsigned int i = 0; i < arg_count; i++) {
        Value* opr = funNode->getOperand(2 + i);
        if (opr == NULL) {
          scheme[i] = NULL;
        } else {
          assert (dyn_cast<Constant>(opr) != NULL);
          scheme[i] = opr;
        }
      }

      this->addSpecialization(prin, scheme, spec, false);
      errs() << "recording specialization of '" << prin->getName() << "' to '" << spec->getName() << "'\n";
    }
#endif /* RECORD_IN_METADATA */
  }

MDNode *MDNode::getMostGenericTBAA(MDNode *A, MDNode *B) {
  if (!A || !B)
    return NULL;

  if (A == B)
    return A;

  // For struct-path aware TBAA, we use the access type of the tag.
  bool StructPath = isStructPathTBAA(A);
  if (StructPath) {
    A = cast_or_null<MDNode>(A->getOperand(1));
    if (!A) return 0;
    B = cast_or_null<MDNode>(B->getOperand(1));
    if (!B) return 0;
  }

  SmallVector<MDNode *, 4> PathA;
  MDNode *T = A;
  while (T) {
    PathA.push_back(T);
    T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0;
  }

  SmallVector<MDNode *, 4> PathB;
  T = B;
  while (T) {
    PathB.push_back(T);
    T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0;
  }

  int IA = PathA.size() - 1;
  int IB = PathB.size() - 1;

  MDNode *Ret = 0;
  while (IA >= 0 && IB >=0) {
    if (PathA[IA] == PathB[IB])
      Ret = PathA[IA];
    else
      break;
    --IA;
    --IB;
  }
  if (!StructPath)
    return Ret;

  if (!Ret)
    return 0;
  // We need to convert from a type node to a tag node.
  Type *Int64 = IntegerType::get(A->getContext(), 64);
  Value *Ops[3] = { Ret, Ret, ConstantInt::get(Int64, 0) };
  return MDNode::get(A->getContext(), Ops);
}

Action* IRParser::getAction(llvm::MDNode* node) {
    Value* idValue = node->getOperand(0);

    if (idValue == NULL){
        map<Function*, Action*>::iterator it;

        // Action has not tag, find it by its function name
        Function* function = getBodyFunction(node);
        it = untaggedActions.find(function);

        return it->second;
    }

    //Get identifiers of action tag
    map<std::string, Action*>::iterator it;
    ActionTag tag;
    MDNode* idNode = cast<MDNode>(idValue);

    for (unsigned i = 0, e = idNode->getNumOperands(); i != e; ++i){
        MDString* tagMD = cast<MDString>(idNode->getOperand(i));
        tag.add(tagMD->getString());
    }

    it = actions.find(tag.getIdentifier());

    return it->second;
}

MDNode *Loop::getLoopID() const {
  MDNode *LoopID = nullptr;
  if (isLoopSimplifyForm()) {
    LoopID = getLoopLatch()->getTerminator()->getMetadata(LoopMDName);
  } else {
    // Go through each predecessor of the loop header and check the
    // terminator for the metadata.
    BasicBlock *H = getHeader();
    for (block_iterator I = block_begin(), IE = block_end(); I != IE; ++I) {
      TerminatorInst *TI = (*I)->getTerminator();
      MDNode *MD = nullptr;

      // Check if this terminator branches to the loop header.
      for (unsigned i = 0, ie = TI->getNumSuccessors(); i != ie; ++i) {
        if (TI->getSuccessor(i) == H) {
          MD = TI->getMetadata(LoopMDName);
          break;
        }
      }
      if (!MD)
        return nullptr;

      if (!LoopID)
        LoopID = MD;
      else if (MD != LoopID)
        return nullptr;
    }
  }
  if (!LoopID || LoopID->getNumOperands() == 0 ||
      LoopID->getOperand(0) != LoopID)
    return nullptr;
  return LoopID;
}

MDNode *Loop::getLoopID() const {
  MDNode *LoopID = nullptr;
  if (isLoopSimplifyForm()) {
    LoopID = getLoopLatch()->getTerminator()->getMetadata(LLVMContext::MD_loop);
  } else {
    // Go through each predecessor of the loop header and check the
    // terminator for the metadata.
    BasicBlock *H = getHeader();
    for (BasicBlock *BB : this->blocks()) {
      TerminatorInst *TI = BB->getTerminator();
      MDNode *MD = nullptr;

      // Check if this terminator branches to the loop header.
      for (BasicBlock *Successor : TI->successors()) {
        if (Successor == H) {
          MD = TI->getMetadata(LLVMContext::MD_loop);
          break;
        }
      }
      if (!MD)
        return nullptr;

      if (!LoopID)
        LoopID = MD;
      else if (MD != LoopID)
        return nullptr;
    }
  }
  if (!LoopID || LoopID->getNumOperands() == 0 ||
      LoopID->getOperand(0) != LoopID)
    return nullptr;
  return LoopID;
}

/// parseMetadata - Parse metadata from the module
void LTOModule::parseMetadata() {
  raw_string_ostream OS(LinkerOpts);

  // Linker Options
  if (NamedMDNode *LinkerOptions =
          getModule().getNamedMetadata("llvm.linker.options")) {
    for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
      MDNode *MDOptions = LinkerOptions->getOperand(i);
      for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
        MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
        OS << " " << MDOption->getString();
      }
    }
  }

  // Globals - we only need to do this for COFF.
  const Triple TT(_target->getTargetTriple());
  if (!TT.isOSBinFormatCOFF())
    return;
  Mangler M;
  for (const NameAndAttributes &Sym : _symbols) {
    if (!Sym.symbol)
      continue;
    emitLinkerFlagsForGlobalCOFF(OS, Sym.symbol, TT, M);
  }

  // Add other interesting metadata here.
}

/// 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;
}