CFGPrinter.h

Go to the documentation of this file.

//===-- CFGPrinter.h - CFG printer external interface -----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines a 'dot-cfg' analysis pass, which emits the
// cfg.<fnname>.dot file for each function in the program, with a graph of the
// CFG for that function.
//
// This file defines external functions that can be called to explicitly
// instantiate the CFG printer.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_ANALYSIS_CFGPRINTER_H
#define LLVM_ANALYSIS_CFGPRINTER_H
 
#include "llvm/Analysis/BlockFrequencyInfo.h"
#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/HeatUtils.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/ProfDataUtils.h"
#include "llvm/Support/DOTGraphTraits.h"
#include "llvm/Support/FormatVariadic.h"
 
namespace llvm {
template <class GraphType> struct GraphTraits;
class CFGViewerPass : public PassInfoMixin<CFGViewerPass> {
public:
  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
  static bool isRequired() { return true; }
};
 
class CFGOnlyViewerPass : public PassInfoMixin<CFGOnlyViewerPass> {
public:
  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
  static bool isRequired() { return true; }
};
 
class CFGPrinterPass : public PassInfoMixin<CFGPrinterPass> {
public:
  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
  static bool isRequired() { return true; }
};
 
class CFGOnlyPrinterPass : public PassInfoMixin<CFGOnlyPrinterPass> {
public:
  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
  static bool isRequired() { return true; }
};
 
class DOTFuncInfo {
private:
  const Function *F;
  const BlockFrequencyInfo *BFI;
  const BranchProbabilityInfo *BPI;
  uint64_t MaxFreq;
  bool ShowHeat;
  bool EdgeWeights;
  bool RawWeights;
 
public:
  DOTFuncInfo(const Function *F) : DOTFuncInfo(F, nullptr, nullptr, 0) {}
 
  DOTFuncInfo(const Function *F, const BlockFrequencyInfo *BFI,
              const BranchProbabilityInfo *BPI, uint64_t MaxFreq)
      : F(F), BFI(BFI), BPI(BPI), MaxFreq(MaxFreq) {
    ShowHeat = false;
    EdgeWeights = !!BPI; // Print EdgeWeights when BPI is available.
    RawWeights = !!BFI;  // Print RawWeights when BFI is available.
  }
 
  const BlockFrequencyInfo *getBFI() const { return BFI; }
 
  const BranchProbabilityInfo *getBPI() const { return BPI; }
 
  const Function *getFunction() const { return this->F; }
 
  uint64_t getMaxFreq() const { return MaxFreq; }
 
  uint64_t getFreq(const BasicBlock *BB) const {
    return BFI->getBlockFreq(BB).getFrequency();
  }
 
  void setHeatColors(bool ShowHeat) { this->ShowHeat = ShowHeat; }
 
  bool showHeatColors() { return ShowHeat; }
 
  void setRawEdgeWeights(bool RawWeights) { this->RawWeights = RawWeights; }
 
  bool useRawEdgeWeights() { return RawWeights; }
 
  void setEdgeWeights(bool EdgeWeights) { this->EdgeWeights = EdgeWeights; }
 
  bool showEdgeWeights() { return EdgeWeights; }
};
 
template <>
struct GraphTraits<DOTFuncInfo *> : public GraphTraits<const BasicBlock *> {
  static NodeRef getEntryNode(DOTFuncInfo *CFGInfo) {
    return &(CFGInfo->getFunction()->getEntryBlock());
  }
 
  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
  using nodes_iterator = pointer_iterator<Function::const_iterator>;
 
  static nodes_iterator nodes_begin(DOTFuncInfo *CFGInfo) {
    return nodes_iterator(CFGInfo->getFunction()->begin());
  }
 
  static nodes_iterator nodes_end(DOTFuncInfo *CFGInfo) {
    return nodes_iterator(CFGInfo->getFunction()->end());
  }
 
  static size_t size(DOTFuncInfo *CFGInfo) {
    return CFGInfo->getFunction()->size();
  }
};
 
template <typename BasicBlockT>
std::string SimpleNodeLabelString(const BasicBlockT *Node) {
  if (!Node->getName().empty())
    return Node->getName().str();
 
  std::string Str;
  raw_string_ostream OS(Str);
 
  Node->printAsOperand(OS, false);
  return Str;
}
 
template <typename BasicBlockT>
std::string CompleteNodeLabelString(
    const BasicBlockT *Node,
    function_ref<void(raw_string_ostream &, const BasicBlockT &)>
        HandleBasicBlock,
    function_ref<void(std::string &, unsigned &, unsigned)>
        HandleComment) {
 
  enum { MaxColumns = 80 };
  std::string OutStr;
  raw_string_ostream OS(OutStr);
  HandleBasicBlock(OS, *Node);
  // Remove "%" from BB name
  if (OutStr[0] == '%') {
    OutStr.erase(OutStr.begin());
  }
  // Place | after BB name to separate it into header
  OutStr.insert(OutStr.find_first_of('\n') + 1, "\\|");
 
  unsigned ColNum = 0;
  unsigned LastSpace = 0;
  for (unsigned i = 0; i != OutStr.length(); ++i) {
    if (OutStr[i] == '\n') { // Left justify
      OutStr[i] = '\\';
      OutStr.insert(OutStr.begin() + i + 1, 'l');
      ColNum = 0;
      LastSpace = 0;
    } else if (OutStr[i] == ';') {             // Delete comments!
      unsigned Idx = OutStr.find('\n', i + 1); // Find end of line
      HandleComment(OutStr, i, Idx);
    } else if (ColNum == MaxColumns) { // Wrap lines.
      // Wrap very long names even though we can't find a space.
      if (!LastSpace)
        LastSpace = i;
      OutStr.insert(LastSpace, "\\l...");
      ColNum = i - LastSpace;
      LastSpace = 0;
      i += 3; // The loop will advance 'i' again.
    } else
      ++ColNum;
    if (OutStr[i] == ' ')
      LastSpace = i;
  }
  return OutStr;
}
 
template <>
struct DOTGraphTraits<DOTFuncInfo *> : public DefaultDOTGraphTraits {
 
  // Cache for is hidden property
  DenseMap<const BasicBlock *, bool> isOnDeoptOrUnreachablePath;
 
  DOTGraphTraits(bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}
 
  static void eraseComment(std::string &OutStr, unsigned &I, unsigned Idx) {
    OutStr.erase(OutStr.begin() + I, OutStr.begin() + Idx);
    --I;
  }
 
  static std::string getGraphName(DOTFuncInfo *CFGInfo) {
    return "CFG for '" + CFGInfo->getFunction()->getName().str() + "' function";
  }
 
  static std::string getSimpleNodeLabel(const BasicBlock *Node, DOTFuncInfo *) {
    return SimpleNodeLabelString(Node);
  }
 
  static void printBasicBlock(raw_string_ostream &OS, const BasicBlock &Node) {
    // Prepend label name
    Node.printAsOperand(OS, false);
    OS << ":\n";
    for (const Instruction &Inst : Node)
      OS << Inst << "\n";
  }
 
  static std::string getCompleteNodeLabel(
      const BasicBlock *Node, DOTFuncInfo *,
      function_ref<void(raw_string_ostream &, const BasicBlock &)>
          HandleBasicBlock = printBasicBlock,
      function_ref<void(std::string &, unsigned &, unsigned)>
          HandleComment = eraseComment) {
    return CompleteNodeLabelString(Node, HandleBasicBlock, HandleComment);
  }
 
  std::string getNodeLabel(const BasicBlock *Node, DOTFuncInfo *CFGInfo) {
 
    if (isSimple())
      return getSimpleNodeLabel(Node, CFGInfo);
    else
      return getCompleteNodeLabel(Node, CFGInfo);
  }
 
  static std::string getEdgeSourceLabel(const BasicBlock *Node,
                                        const_succ_iterator I) {
    // Label source of conditional branches with "T" or "F"
    if (const BranchInst *BI = dyn_cast<BranchInst>(Node->getTerminator()))
      if (BI->isConditional())
        return (I == succ_begin(Node)) ? "T" : "F";
 
    // Label source of switch edges with the associated value.
    if (const SwitchInst *SI = dyn_cast<SwitchInst>(Node->getTerminator())) {
      unsigned SuccNo = I.getSuccessorIndex();
 
      if (SuccNo == 0)
        return "def";
 
      std::string Str;
      raw_string_ostream OS(Str);
      auto Case = *SwitchInst::ConstCaseIt::fromSuccessorIndex(SI, SuccNo);
      OS << Case.getCaseValue()->getValue();
      return Str;
    }
    return "";
  }
 
  static std::string getBBName(const BasicBlock *Node) {
    std::string NodeName = Node->getName().str();
    if (NodeName.empty()) {
      raw_string_ostream NodeOS(NodeName);
      Node->printAsOperand(NodeOS, false);
      // Removing %
      NodeName.erase(NodeName.begin());
    }
    return NodeName;
  }
 
  /// Display the raw branch weights from PGO.
  std::string getEdgeAttributes(const BasicBlock *Node, const_succ_iterator I,
                                DOTFuncInfo *CFGInfo) {
    unsigned OpNo = I.getSuccessorIndex();
    const Instruction *TI = Node->getTerminator();
    BasicBlock *SuccBB = TI->getSuccessor(OpNo);
    auto BranchProb = CFGInfo->getBPI()->getEdgeProbability(Node, SuccBB);
    double WeightPercent = ((double)BranchProb.getNumerator()) /
                           ((double)BranchProb.getDenominator());
 
    std::string TTAttr =
        formatv("tooltip=\"{0} -> {1}\\nProbability {2:P}\" ", getBBName(Node),
                getBBName(SuccBB), WeightPercent);
    if (!CFGInfo->showEdgeWeights())
      return TTAttr;
 
    if (TI->getNumSuccessors() == 1)
      return TTAttr + "penwidth=2";
 
    if (OpNo >= TI->getNumSuccessors())
      return TTAttr;
 
    double Width = 1 + WeightPercent;
 
    if (!CFGInfo->useRawEdgeWeights())
      return TTAttr +
             formatv("label=\"{0:P}\" penwidth={1}", WeightPercent, Width)
                 .str();
 
    // Prepend a 'W' to indicate that this is a weight rather than the actual
    // profile count (due to scaling).
 
    uint64_t Freq = CFGInfo->getFreq(Node);
    std::string Attrs =
        TTAttr + formatv("label=\"W:{0}\" penwidth={1}",
                         (uint64_t)(Freq * WeightPercent), Width)
                     .str();
    if (Attrs.size())
      return Attrs;
 
    MDNode *WeightsNode = getBranchWeightMDNode(*TI);
    if (!WeightsNode)
      return TTAttr;
 
    OpNo = I.getSuccessorIndex() + 1;
    if (OpNo >= WeightsNode->getNumOperands())
      return TTAttr;
    ConstantInt *Weight =
        mdconst::dyn_extract<ConstantInt>(WeightsNode->getOperand(OpNo));
    if (!Weight)
      return TTAttr;
    return (TTAttr + "label=\"W:" + std::to_string(Weight->getZExtValue()) +
            "\" penwidth=" + std::to_string(Width));
  }
 
  std::string getNodeAttributes(const BasicBlock *Node, DOTFuncInfo *CFGInfo) {
 
    if (!CFGInfo->showHeatColors())
      return "";
 
    uint64_t Freq = CFGInfo->getFreq(Node);
    std::string Color = getHeatColor(Freq, CFGInfo->getMaxFreq());
    std::string EdgeColor = (Freq <= (CFGInfo->getMaxFreq() / 2))
                                ? (getHeatColor(0))
                                : (getHeatColor(1));
 
    std::string Attrs = "color=\"" + EdgeColor + "ff\", style=filled," +
                        " fillcolor=\"" + Color + "70\"" +
                        " fontname=\"Courier\"";
    return Attrs;
  }
  bool isNodeHidden(const BasicBlock *Node, const DOTFuncInfo *CFGInfo);
  void computeDeoptOrUnreachablePaths(const Function *F);
};
} // End llvm namespace
 
#endif