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1//===-- ModuleSummaryIndex.cpp - Module Summary Index ---------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// This file implements the module index and summary classes for the10// IR library.11//12//===----------------------------------------------------------------------===//13 14#include "llvm/IR/ModuleSummaryIndex.h"15#include "llvm/ADT/SCCIterator.h"16#include "llvm/ADT/Statistic.h"17#include "llvm/Support/CommandLine.h"18#include "llvm/Support/Path.h"19#include "llvm/Support/raw_ostream.h"20using namespace llvm;21 22#define DEBUG_TYPE "module-summary-index"23 24STATISTIC(ReadOnlyLiveGVars,25          "Number of live global variables marked read only");26STATISTIC(WriteOnlyLiveGVars,27          "Number of live global variables marked write only");28 29static cl::opt<bool> PropagateAttrs("propagate-attrs", cl::init(true),30                                    cl::Hidden,31                                    cl::desc("Propagate attributes in index"));32 33static cl::opt<bool> ImportConstantsWithRefs(34    "import-constants-with-refs", cl::init(true), cl::Hidden,35    cl::desc("Import constant global variables with references"));36 37FunctionSummary FunctionSummary::ExternalNode =38    FunctionSummary::makeDummyFunctionSummary(39        SmallVector<FunctionSummary::EdgeTy, 0>());40 41GlobalValue::VisibilityTypes ValueInfo::getELFVisibility() const {42  bool HasProtected = false;43  for (const auto &S : make_pointee_range(getSummaryList())) {44    if (S.getVisibility() == GlobalValue::HiddenVisibility)45      return GlobalValue::HiddenVisibility;46    if (S.getVisibility() == GlobalValue::ProtectedVisibility)47      HasProtected = true;48  }49  return HasProtected ? GlobalValue::ProtectedVisibility50                      : GlobalValue::DefaultVisibility;51}52 53bool ValueInfo::isDSOLocal(bool WithDSOLocalPropagation) const {54  // With DSOLocal propagation done, the flag in evey summary is the same.55  // Check the first one is enough.56  return WithDSOLocalPropagation57             ? getSummaryList().size() && getSummaryList()[0]->isDSOLocal()58             : getSummaryList().size() &&59                   llvm::all_of(60                       getSummaryList(),61                       [](const std::unique_ptr<GlobalValueSummary> &Summary) {62                         return Summary->isDSOLocal();63                       });64}65 66bool ValueInfo::canAutoHide() const {67  // Can only auto hide if all copies are eligible to auto hide.68  return getSummaryList().size() &&69         llvm::all_of(getSummaryList(),70                      [](const std::unique_ptr<GlobalValueSummary> &Summary) {71                        return Summary->canAutoHide();72                      });73}74 75// Gets the number of readonly and writeonly refs in RefEdgeList76std::pair<unsigned, unsigned> FunctionSummary::specialRefCounts() const {77  // Here we take advantage of having all readonly and writeonly references78  // located in the end of the RefEdgeList.79  auto Refs = refs();80  unsigned RORefCnt = 0, WORefCnt = 0;81  int I;82  for (I = Refs.size() - 1; I >= 0 && Refs[I].isWriteOnly(); --I)83    WORefCnt++;84  for (; I >= 0 && Refs[I].isReadOnly(); --I)85    RORefCnt++;86  return {RORefCnt, WORefCnt};87}88 89uint64_t ModuleSummaryIndex::getFlags() const {90  uint64_t Flags = 0;91  // Flags & 0x4 is reserved. DO NOT REUSE.92  if (withGlobalValueDeadStripping())93    Flags |= 0x1;94  if (skipModuleByDistributedBackend())95    Flags |= 0x2;96  if (enableSplitLTOUnit())97    Flags |= 0x8;98  if (partiallySplitLTOUnits())99    Flags |= 0x10;100  if (withAttributePropagation())101    Flags |= 0x20;102  if (withDSOLocalPropagation())103    Flags |= 0x40;104  if (withWholeProgramVisibility())105    Flags |= 0x80;106  if (withSupportsHotColdNew())107    Flags |= 0x100;108  if (hasUnifiedLTO())109    Flags |= 0x200;110  if (withInternalizeAndPromote())111    Flags |= 0x400;112  return Flags;113}114 115void ModuleSummaryIndex::setFlags(uint64_t Flags) {116  assert(Flags <= 0x7ff && "Unexpected bits in flag");117  // 1 bit: WithGlobalValueDeadStripping flag.118  // Set on combined index only.119  if (Flags & 0x1)120    setWithGlobalValueDeadStripping();121  // 1 bit: SkipModuleByDistributedBackend flag.122  // Set on combined index only.123  if (Flags & 0x2)124    setSkipModuleByDistributedBackend();125  // Flags & 0x4 is reserved. DO NOT REUSE.126  // 1 bit: DisableSplitLTOUnit flag.127  // Set on per module indexes. It is up to the client to validate128  // the consistency of this flag across modules being linked.129  if (Flags & 0x8)130    setEnableSplitLTOUnit();131  // 1 bit: PartiallySplitLTOUnits flag.132  // Set on combined index only.133  if (Flags & 0x10)134    setPartiallySplitLTOUnits();135  // 1 bit: WithAttributePropagation flag.136  // Set on combined index only.137  if (Flags & 0x20)138    setWithAttributePropagation();139  // 1 bit: WithDSOLocalPropagation flag.140  // Set on combined index only.141  if (Flags & 0x40)142    setWithDSOLocalPropagation();143  // 1 bit: WithWholeProgramVisibility flag.144  // Set on combined index only.145  if (Flags & 0x80)146    setWithWholeProgramVisibility();147  // 1 bit: WithSupportsHotColdNew flag.148  // Set on combined index only.149  if (Flags & 0x100)150    setWithSupportsHotColdNew();151  // 1 bit: WithUnifiedLTO flag.152  // Set on combined index only.153  if (Flags & 0x200)154    setUnifiedLTO();155  // 1 bit: WithInternalizeAndPromote flag.156  // Set on combined index only.157  if (Flags & 0x400)158    setWithInternalizeAndPromote();159}160 161// Collect for the given module the list of function it defines162// (GUID -> Summary).163void ModuleSummaryIndex::collectDefinedFunctionsForModule(164    StringRef ModulePath, GVSummaryMapTy &GVSummaryMap) const {165  for (auto &GlobalList : *this) {166    auto GUID = GlobalList.first;167    for (auto &GlobSummary : GlobalList.second.getSummaryList()) {168      auto *Summary = dyn_cast_or_null<FunctionSummary>(GlobSummary.get());169      if (!Summary)170        // Ignore global variable, focus on functions171        continue;172      // Ignore summaries from other modules.173      if (Summary->modulePath() != ModulePath)174        continue;175      GVSummaryMap[GUID] = Summary;176    }177  }178}179 180GlobalValueSummary *181ModuleSummaryIndex::getGlobalValueSummary(uint64_t ValueGUID,182                                          bool PerModuleIndex) const {183  auto VI = getValueInfo(ValueGUID);184  assert(VI && "GlobalValue not found in index");185  assert((!PerModuleIndex || VI.getSummaryList().size() == 1) &&186         "Expected a single entry per global value in per-module index");187  auto &Summary = VI.getSummaryList()[0];188  return Summary.get();189}190 191bool ModuleSummaryIndex::isGUIDLive(GlobalValue::GUID GUID) const {192  auto VI = getValueInfo(GUID);193  if (!VI)194    return true;195  const auto &SummaryList = VI.getSummaryList();196  if (SummaryList.empty())197    return true;198  for (auto &I : SummaryList)199    if (isGlobalValueLive(I.get()))200      return true;201  return false;202}203 204static void205propagateAttributesToRefs(GlobalValueSummary *S,206                          DenseSet<ValueInfo> &MarkedNonReadWriteOnly) {207  // If reference is not readonly or writeonly then referenced summary is not208  // read/writeonly either. Note that:209  // - All references from GlobalVarSummary are conservatively considered as210  //   not readonly or writeonly. Tracking them properly requires more complex211  //   analysis then we have now.212  //213  // - AliasSummary objects have no refs at all so this function is a no-op214  //   for them.215  for (auto &VI : S->refs()) {216    assert(VI.getAccessSpecifier() == 0 || isa<FunctionSummary>(S));217    if (!VI.getAccessSpecifier()) {218      if (!MarkedNonReadWriteOnly.insert(VI).second)219        continue;220    } else if (MarkedNonReadWriteOnly.contains(VI))221      continue;222    for (auto &Ref : VI.getSummaryList())223      // If references to alias is not read/writeonly then aliasee224      // is not read/writeonly225      if (auto *GVS = dyn_cast<GlobalVarSummary>(Ref->getBaseObject())) {226        if (!VI.isReadOnly())227          GVS->setReadOnly(false);228        if (!VI.isWriteOnly())229          GVS->setWriteOnly(false);230      }231  }232}233 234// Do the access attribute and DSOLocal propagation in combined index.235// The goal of attribute propagation is internalization of readonly (RO)236// or writeonly (WO) variables. To determine which variables are RO or WO237// and which are not we take following steps:238// - During analysis we speculatively assign readonly and writeonly239//   attribute to all variables which can be internalized. When computing240//   function summary we also assign readonly or writeonly attribute to a241//   reference if function doesn't modify referenced variable (readonly)242//   or doesn't read it (writeonly).243//244// - After computing dead symbols in combined index we do the attribute245//   and DSOLocal propagation. During this step we:246//   a. clear RO and WO attributes from variables which are preserved or247//      can't be imported248//   b. clear RO and WO attributes from variables referenced by any global249//      variable initializer250//   c. clear RO attribute from variable referenced by a function when251//      reference is not readonly252//   d. clear WO attribute from variable referenced by a function when253//      reference is not writeonly254//   e. clear IsDSOLocal flag in every summary if any of them is false.255//256//   Because of (c, d) we don't internalize variables read by function A257//   and modified by function B.258//259// Internalization itself happens in the backend after import is finished260// See internalizeGVsAfterImport.261void ModuleSummaryIndex::propagateAttributes(262    const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols) {263  if (!PropagateAttrs)264    return;265  DenseSet<ValueInfo> MarkedNonReadWriteOnly;266  for (auto &P : *this) {267    bool IsDSOLocal = true;268    for (auto &S : P.second.getSummaryList()) {269      if (!isGlobalValueLive(S.get())) {270        // computeDeadSymbolsAndUpdateIndirectCalls should have marked all271        // copies live. Note that it is possible that there is a GUID collision272        // between internal symbols with the same name in different files of the273        // same name but not enough distinguishing path. Because274        // computeDeadSymbolsAndUpdateIndirectCalls should conservatively mark275        // all copies live we can assert here that all are dead if any copy is276        // dead.277        assert(llvm::none_of(278            P.second.getSummaryList(),279            [&](const std::unique_ptr<GlobalValueSummary> &Summary) {280              return isGlobalValueLive(Summary.get());281            }));282        // We don't examine references from dead objects283        break;284      }285 286      // Global variable can't be marked read/writeonly if it is not eligible287      // to import since we need to ensure that all external references get288      // a local (imported) copy. It also can't be marked read/writeonly if289      // it or any alias (since alias points to the same memory) are preserved290      // or notEligibleToImport, since either of those means there could be291      // writes (or reads in case of writeonly) that are not visible (because292      // preserved means it could have external to DSO writes or reads, and293      // notEligibleToImport means it could have writes or reads via inline294      // assembly leading it to be in the @llvm.*used).295      if (auto *GVS = dyn_cast<GlobalVarSummary>(S->getBaseObject()))296        // Here we intentionally pass S.get() not GVS, because S could be297        // an alias. We don't analyze references here, because we have to298        // know exactly if GV is readonly to do so.299        if (!canImportGlobalVar(S.get(), /* AnalyzeRefs */ false) ||300            GUIDPreservedSymbols.count(P.first)) {301          GVS->setReadOnly(false);302          GVS->setWriteOnly(false);303        }304      propagateAttributesToRefs(S.get(), MarkedNonReadWriteOnly);305 306      // If the flag from any summary is false, the GV is not DSOLocal.307      IsDSOLocal &= S->isDSOLocal();308    }309    if (!IsDSOLocal)310      // Mark the flag in all summaries false so that we can do quick check311      // without going through the whole list.312      for (const std::unique_ptr<GlobalValueSummary> &Summary :313           P.second.getSummaryList())314        Summary->setDSOLocal(false);315  }316  setWithAttributePropagation();317  setWithDSOLocalPropagation();318  if (llvm::AreStatisticsEnabled())319    for (auto &P : *this)320      if (P.second.getSummaryList().size())321        if (auto *GVS = dyn_cast<GlobalVarSummary>(322                P.second.getSummaryList()[0]->getBaseObject()))323          if (isGlobalValueLive(GVS)) {324            if (GVS->maybeReadOnly())325              ReadOnlyLiveGVars++;326            if (GVS->maybeWriteOnly())327              WriteOnlyLiveGVars++;328          }329}330 331bool ModuleSummaryIndex::canImportGlobalVar(const GlobalValueSummary *S,332                                            bool AnalyzeRefs) const {333  bool CanImportDecl;334  return canImportGlobalVar(S, AnalyzeRefs, CanImportDecl);335}336 337bool ModuleSummaryIndex::canImportGlobalVar(const GlobalValueSummary *S,338                                            bool AnalyzeRefs,339                                            bool &CanImportDecl) const {340  auto HasRefsPreventingImport = [this](const GlobalVarSummary *GVS) {341    // We don't analyze GV references during attribute propagation, so342    // GV with non-trivial initializer can be marked either read or343    // write-only.344    // Importing definiton of readonly GV with non-trivial initializer345    // allows us doing some extra optimizations (like converting indirect346    // calls to direct).347    // Definition of writeonly GV with non-trivial initializer should also348    // be imported. Not doing so will result in:349    // a) GV internalization in source module (because it's writeonly)350    // b) Importing of GV declaration to destination module as a result351    //    of promotion.352    // c) Link error (external declaration with internal definition).353    // However we do not promote objects referenced by writeonly GV354    // initializer by means of converting it to 'zeroinitializer'355    return !(ImportConstantsWithRefs && GVS->isConstant()) &&356           !isReadOnly(GVS) && !isWriteOnly(GVS) && GVS->refs().size();357  };358  auto *GVS = cast<GlobalVarSummary>(S->getBaseObject());359 360  const bool nonInterposable =361      !GlobalValue::isInterposableLinkage(S->linkage());362  const bool eligibleToImport = !S->notEligibleToImport();363 364  // It's correct to import a global variable only when it is not interposable365  // and eligible to import.366  CanImportDecl = (nonInterposable && eligibleToImport);367 368  // Global variable with non-trivial initializer can be imported369  // if it's readonly. This gives us extra opportunities for constant370  // folding and converting indirect calls to direct calls. We don't371  // analyze GV references during attribute propagation, because we372  // don't know yet if it is readonly or not.373  return nonInterposable && eligibleToImport &&374         (!AnalyzeRefs || !HasRefsPreventingImport(GVS));375}376 377// TODO: write a graphviz dumper for SCCs (see ModuleSummaryIndex::exportToDot)378// then delete this function and update its tests379LLVM_DUMP_METHOD380void ModuleSummaryIndex::dumpSCCs(raw_ostream &O) {381  for (scc_iterator<ModuleSummaryIndex *> I =382           scc_begin<ModuleSummaryIndex *>(this);383       !I.isAtEnd(); ++I) {384    O << "SCC (" << utostr(I->size()) << " node" << (I->size() == 1 ? "" : "s")385      << ") {\n";386    for (const ValueInfo &V : *I) {387      FunctionSummary *F = nullptr;388      if (V.getSummaryList().size())389        F = cast<FunctionSummary>(V.getSummaryList().front().get());390      O << " " << (F == nullptr ? "External" : "") << " " << utostr(V.getGUID())391        << (I.hasCycle() ? " (has cycle)" : "") << "\n";392    }393    O << "}\n";394  }395}396 397namespace {398struct Attributes {399  void add(const Twine &Name, const Twine &Value,400           const Twine &Comment = Twine());401  void addComment(const Twine &Comment);402  std::string getAsString() const;403 404  std::vector<std::string> Attrs;405  std::string Comments;406};407 408struct Edge {409  uint64_t SrcMod;410  int Hotness;411  GlobalValue::GUID Src;412  GlobalValue::GUID Dst;413};414} // namespace415 416void Attributes::add(const Twine &Name, const Twine &Value,417                     const Twine &Comment) {418  std::string A = Name.str();419  A += "=\"";420  A += Value.str();421  A += "\"";422  Attrs.push_back(A);423  addComment(Comment);424}425 426void Attributes::addComment(const Twine &Comment) {427  if (!Comment.isTriviallyEmpty()) {428    if (Comments.empty())429      Comments = " // ";430    else431      Comments += ", ";432    Comments += Comment.str();433  }434}435 436std::string Attributes::getAsString() const {437  if (Attrs.empty())438    return "";439 440  std::string Ret = "[";441  for (auto &A : Attrs)442    Ret += A + ",";443  Ret.pop_back();444  Ret += "];";445  Ret += Comments;446  return Ret;447}448 449static std::string linkageToString(GlobalValue::LinkageTypes LT) {450  switch (LT) {451  case GlobalValue::ExternalLinkage:452    return "extern";453  case GlobalValue::AvailableExternallyLinkage:454    return "av_ext";455  case GlobalValue::LinkOnceAnyLinkage:456    return "linkonce";457  case GlobalValue::LinkOnceODRLinkage:458    return "linkonce_odr";459  case GlobalValue::WeakAnyLinkage:460    return "weak";461  case GlobalValue::WeakODRLinkage:462    return "weak_odr";463  case GlobalValue::AppendingLinkage:464    return "appending";465  case GlobalValue::InternalLinkage:466    return "internal";467  case GlobalValue::PrivateLinkage:468    return "private";469  case GlobalValue::ExternalWeakLinkage:470    return "extern_weak";471  case GlobalValue::CommonLinkage:472    return "common";473  }474 475  return "<unknown>";476}477 478static std::string fflagsToString(FunctionSummary::FFlags F) {479  auto FlagValue = [](unsigned V) { return V ? '1' : '0'; };480  char FlagRep[] = {FlagValue(F.ReadNone),481                    FlagValue(F.ReadOnly),482                    FlagValue(F.NoRecurse),483                    FlagValue(F.ReturnDoesNotAlias),484                    FlagValue(F.NoInline),485                    FlagValue(F.AlwaysInline),486                    FlagValue(F.NoUnwind),487                    FlagValue(F.MayThrow),488                    FlagValue(F.HasUnknownCall),489                    FlagValue(F.MustBeUnreachable),490                    0};491 492  return FlagRep;493}494 495// Get string representation of function instruction count and flags.496static std::string getSummaryAttributes(GlobalValueSummary* GVS) {497  auto *FS = dyn_cast_or_null<FunctionSummary>(GVS);498  if (!FS)499    return "";500 501  return std::string("inst: ") + std::to_string(FS->instCount()) +502         ", ffl: " + fflagsToString(FS->fflags());503}504 505static std::string getNodeVisualName(GlobalValue::GUID Id) {506  return std::string("@") + std::to_string(Id);507}508 509static std::string getNodeVisualName(const ValueInfo &VI) {510  return VI.name().empty() ? getNodeVisualName(VI.getGUID()) : VI.name().str();511}512 513static std::string getNodeLabel(const ValueInfo &VI, GlobalValueSummary *GVS) {514  if (isa<AliasSummary>(GVS))515    return getNodeVisualName(VI);516 517  std::string Attrs = getSummaryAttributes(GVS);518  std::string Label =519      getNodeVisualName(VI) + "|" + linkageToString(GVS->linkage());520  if (!Attrs.empty())521    Label += std::string(" (") + Attrs + ")";522  Label += "}";523 524  return Label;525}526 527// Write definition of external node, which doesn't have any528// specific module associated with it. Typically this is function529// or variable defined in native object or library.530static void defineExternalNode(raw_ostream &OS, const char *Pfx,531                               const ValueInfo &VI, GlobalValue::GUID Id) {532  auto StrId = std::to_string(Id);533  OS << "  " << StrId << " [label=\"";534 535  if (VI) {536    OS << getNodeVisualName(VI);537  } else {538    OS << getNodeVisualName(Id);539  }540  OS << "\"]; // defined externally\n";541}542 543static bool hasReadOnlyFlag(const GlobalValueSummary *S) {544  if (auto *GVS = dyn_cast<GlobalVarSummary>(S))545    return GVS->maybeReadOnly();546  return false;547}548 549static bool hasWriteOnlyFlag(const GlobalValueSummary *S) {550  if (auto *GVS = dyn_cast<GlobalVarSummary>(S))551    return GVS->maybeWriteOnly();552  return false;553}554 555static bool hasConstantFlag(const GlobalValueSummary *S) {556  if (auto *GVS = dyn_cast<GlobalVarSummary>(S))557    return GVS->isConstant();558  return false;559}560 561void ModuleSummaryIndex::exportToDot(562    raw_ostream &OS,563    const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols) const {564  std::vector<Edge> CrossModuleEdges;565  DenseMap<GlobalValue::GUID, std::vector<uint64_t>> NodeMap;566  using GVSOrderedMapTy = std::map<GlobalValue::GUID, GlobalValueSummary *>;567  std::map<StringRef, GVSOrderedMapTy> ModuleToDefinedGVS;568  collectDefinedGVSummariesPerModule(ModuleToDefinedGVS);569 570  // Assign an id to each module path for use in graph labels. Since the571  // StringMap iteration order isn't guaranteed, order by path string before572  // assigning ids.573  std::vector<StringRef> ModulePaths;574  for (auto &[ModPath, _] : modulePaths())575    ModulePaths.push_back(ModPath);576  llvm::sort(ModulePaths);577  DenseMap<StringRef, uint64_t> ModuleIdMap;578  for (auto &ModPath : ModulePaths)579    ModuleIdMap.try_emplace(ModPath, ModuleIdMap.size());580 581  // Get node identifier in form MXXX_<GUID>. The MXXX prefix is required,582  // because we may have multiple linkonce functions summaries.583  auto NodeId = [](uint64_t ModId, GlobalValue::GUID Id) {584    return ModId == (uint64_t)-1 ? std::to_string(Id)585                                 : std::string("M") + std::to_string(ModId) +586                                       "_" + std::to_string(Id);587  };588 589  auto DrawEdge = [&](const char *Pfx, uint64_t SrcMod, GlobalValue::GUID SrcId,590                      uint64_t DstMod, GlobalValue::GUID DstId,591                      int TypeOrHotness) {592    // 0 - alias593    // 1 - reference594    // 2 - constant reference595    // 3 - writeonly reference596    // Other value: (hotness - 4).597    TypeOrHotness += 4;598    static const char *EdgeAttrs[] = {599        " [style=dotted]; // alias",600        " [style=dashed]; // ref",601        " [style=dashed,color=forestgreen]; // const-ref",602        " [style=dashed,color=violetred]; // writeOnly-ref",603        " // call (hotness : Unknown)",604        " [color=blue]; // call (hotness : Cold)",605        " // call (hotness : None)",606        " [color=brown]; // call (hotness : Hot)",607        " [style=bold,color=red]; // call (hotness : Critical)"};608 609    assert(static_cast<size_t>(TypeOrHotness) < std::size(EdgeAttrs));610    OS << Pfx << NodeId(SrcMod, SrcId) << " -> " << NodeId(DstMod, DstId)611       << EdgeAttrs[TypeOrHotness] << "\n";612  };613 614  OS << "digraph Summary {\n";615  for (auto &ModIt : ModuleToDefinedGVS) {616    // Will be empty for a just built per-module index, which doesn't setup a617    // module paths table. In that case use 0 as the module id.618    assert(ModuleIdMap.count(ModIt.first) || ModuleIdMap.empty());619    auto ModId = ModuleIdMap.empty() ? 0 : ModuleIdMap[ModIt.first];620    OS << "  // Module: " << ModIt.first << "\n";621    OS << "  subgraph cluster_" << std::to_string(ModId) << " {\n";622    OS << "    style = filled;\n";623    OS << "    color = lightgrey;\n";624    OS << "    label = \"" << sys::path::filename(ModIt.first) << "\";\n";625    OS << "    node [style=filled,fillcolor=lightblue];\n";626 627    auto &GVSMap = ModIt.second;628    auto Draw = [&](GlobalValue::GUID IdFrom, GlobalValue::GUID IdTo, int Hotness) {629      if (!GVSMap.count(IdTo)) {630        CrossModuleEdges.push_back({ModId, Hotness, IdFrom, IdTo});631        return;632      }633      DrawEdge("    ", ModId, IdFrom, ModId, IdTo, Hotness);634    };635 636    for (auto &SummaryIt : GVSMap) {637      NodeMap[SummaryIt.first].push_back(ModId);638      auto Flags = SummaryIt.second->flags();639      Attributes A;640      if (isa<FunctionSummary>(SummaryIt.second)) {641        A.add("shape", "record", "function");642      } else if (isa<AliasSummary>(SummaryIt.second)) {643        A.add("style", "dotted,filled", "alias");644        A.add("shape", "box");645      } else {646        A.add("shape", "Mrecord", "variable");647        if (Flags.Live && hasReadOnlyFlag(SummaryIt.second))648          A.addComment("immutable");649        if (Flags.Live && hasWriteOnlyFlag(SummaryIt.second))650          A.addComment("writeOnly");651        if (Flags.Live && hasConstantFlag(SummaryIt.second))652          A.addComment("constant");653      }654      if (Flags.Visibility)655        A.addComment("visibility");656      if (Flags.DSOLocal)657        A.addComment("dsoLocal");658      if (Flags.CanAutoHide)659        A.addComment("canAutoHide");660      if (Flags.ImportType == GlobalValueSummary::ImportKind::Definition)661        A.addComment("definition");662      else if (Flags.ImportType == GlobalValueSummary::ImportKind::Declaration)663        A.addComment("declaration");664      if (GUIDPreservedSymbols.count(SummaryIt.first))665        A.addComment("preserved");666 667      auto VI = getValueInfo(SummaryIt.first);668      A.add("label", getNodeLabel(VI, SummaryIt.second));669      if (!Flags.Live)670        A.add("fillcolor", "red", "dead");671      else if (Flags.NotEligibleToImport)672        A.add("fillcolor", "yellow", "not eligible to import");673 674      OS << "    " << NodeId(ModId, SummaryIt.first) << " " << A.getAsString()675         << "\n";676    }677    OS << "    // Edges:\n";678 679    for (auto &SummaryIt : GVSMap) {680      auto *GVS = SummaryIt.second;681      for (auto &R : GVS->refs())682        Draw(SummaryIt.first, R.getGUID(),683             R.isWriteOnly() ? -1 : (R.isReadOnly() ? -2 : -3));684 685      if (auto *AS = dyn_cast_or_null<AliasSummary>(SummaryIt.second)) {686        Draw(SummaryIt.first, AS->getAliaseeGUID(), -4);687        continue;688      }689 690      if (auto *FS = dyn_cast_or_null<FunctionSummary>(SummaryIt.second))691        for (auto &CGEdge : FS->calls())692          Draw(SummaryIt.first, CGEdge.first.getGUID(),693               static_cast<int>(CGEdge.second.Hotness));694    }695    OS << "  }\n";696  }697 698  OS << "  // Cross-module edges:\n";699  for (auto &E : CrossModuleEdges) {700    auto &ModList = NodeMap[E.Dst];701    if (ModList.empty()) {702      defineExternalNode(OS, "  ", getValueInfo(E.Dst), E.Dst);703      // Add fake module to the list to draw an edge to an external node704      // in the loop below.705      ModList.push_back(-1);706    }707    for (auto DstMod : ModList)708      // The edge representing call or ref is drawn to every module where target709      // symbol is defined. When target is a linkonce symbol there can be710      // multiple edges representing a single call or ref, both intra-module and711      // cross-module. As we've already drawn all intra-module edges before we712      // skip it here.713      if (DstMod != E.SrcMod)714        DrawEdge("  ", E.SrcMod, E.Src, DstMod, E.Dst, E.Hotness);715  }716 717  OS << "}";718}719