CbC/CbC_llvm: llvm/lib/IR/ModuleSummaryIndex.cpp comparison

comparison llvm/lib/IR/ModuleSummaryIndex.cpp @ 150:1d019706d866

LLVM10

author	anatofuz
date	Thu, 13 Feb 2020 15:10:13 +0900
parents
children	0572611fdcc8

comparison

equal deleted inserted replaced

-:c2174574ed3a
+:1d019706d866
+//===-- ModuleSummaryIndex.cpp - Module Summary Index ---------------------===//
+//
+// 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 implements the module index and summary classes for the
+// IR library.
+//
+//===----------------------------------------------------------------------===//
+#include "llvm/IR/ModuleSummaryIndex.h"
+#include "llvm/ADT/SCCIterator.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+#define DEBUG_TYPE "module-summary-index"
+STATISTIC(ReadOnlyLiveGVars,
+"Number of live global variables marked read only");
+STATISTIC(WriteOnlyLiveGVars,
+"Number of live global variables marked write only");
+static cl::opt<bool> PropagateAttrs("propagate-attrs", cl::init(true),
+cl::Hidden,
+cl::desc("Propagate attributes in index"));
+// FIXME: Enable again when thin link compile time regressions understood and
+// addressed
+static cl::opt<bool> ImportConstantsWithRefs(
+"import-constants-with-refs", cl::init(false), cl::Hidden,
+cl::desc("Import constant global variables with references"));
+FunctionSummary FunctionSummary::ExternalNode =
+FunctionSummary::makeDummyFunctionSummary({});
+bool ValueInfo::isDSOLocal() const {
+// Need to check all summaries are local in case of hash collisions.
+return getSummaryList().size() &&
+llvm::all_of(getSummaryList(),
+[](const std::unique_ptr<GlobalValueSummary> &Summary) {
+return Summary->isDSOLocal();
+});
+}
+bool ValueInfo::canAutoHide() const {
+// Can only auto hide if all copies are eligible to auto hide.
+return getSummaryList().size() &&
+llvm::all_of(getSummaryList(),
+[](const std::unique_ptr<GlobalValueSummary> &Summary) {
+return Summary->canAutoHide();
+});
+}
+// Gets the number of readonly and writeonly refs in RefEdgeList
+std::pair<unsigned, unsigned> FunctionSummary::specialRefCounts() const {
+// Here we take advantage of having all readonly and writeonly references
+// located in the end of the RefEdgeList.
+auto Refs = refs();
+unsigned RORefCnt = 0, WORefCnt = 0;
+int I;
+for (I = Refs.size() - 1; I >= 0 && Refs[I].isWriteOnly(); --I)
+WORefCnt++;
+for (; I >= 0 && Refs[I].isReadOnly(); --I)
+RORefCnt++;
+return {RORefCnt, WORefCnt};
+}
+constexpr uint64_t ModuleSummaryIndex::BitcodeSummaryVersion;
+// Collect for the given module the list of function it defines
+// (GUID -> Summary).
+void ModuleSummaryIndex::collectDefinedFunctionsForModule(
+StringRef ModulePath, GVSummaryMapTy &GVSummaryMap) const {
+for (auto &GlobalList : *this) {
+auto GUID = GlobalList.first;
+for (auto &GlobSummary : GlobalList.second.SummaryList) {
+auto *Summary = dyn_cast_or_null<FunctionSummary>(GlobSummary.get());
+if (!Summary)
+// Ignore global variable, focus on functions
+continue;
+// Ignore summaries from other modules.
+if (Summary->modulePath() != ModulePath)
+continue;
+GVSummaryMap[GUID] = Summary;
+}
+}
+}
+GlobalValueSummary *
+ModuleSummaryIndex::getGlobalValueSummary(uint64_t ValueGUID,
+bool PerModuleIndex) const {
+auto VI = getValueInfo(ValueGUID);
+assert(VI && "GlobalValue not found in index");
+assert((!PerModuleIndex || VI.getSummaryList().size() == 1) &&
+"Expected a single entry per global value in per-module index");
+auto &Summary = VI.getSummaryList()[0];
+return Summary.get();
+}
+bool ModuleSummaryIndex::isGUIDLive(GlobalValue::GUID GUID) const {
+auto VI = getValueInfo(GUID);
+if (!VI)
+return true;
+const auto &SummaryList = VI.getSummaryList();
+if (SummaryList.empty())
+return true;
+for (auto &I : SummaryList)
+if (isGlobalValueLive(I.get()))
+return true;
+return false;
+}
+static void propagateAttributesToRefs(GlobalValueSummary *S) {
+// If reference is not readonly or writeonly then referenced summary is not
+// read/writeonly either. Note that:
+// - All references from GlobalVarSummary are conservatively considered as
+//   not readonly or writeonly. Tracking them properly requires more complex
+//   analysis then we have now.
+//
+// - AliasSummary objects have no refs at all so this function is a no-op
+//   for them.
+for (auto &VI : S->refs()) {
+assert(VI.getAccessSpecifier() == 0 || isa<FunctionSummary>(S));
+for (auto &Ref : VI.getSummaryList())
+// If references to alias is not read/writeonly then aliasee
+// is not read/writeonly
+if (auto *GVS = dyn_cast<GlobalVarSummary>(Ref->getBaseObject())) {
+if (!VI.isReadOnly())
+GVS->setReadOnly(false);
+if (!VI.isWriteOnly())
+GVS->setWriteOnly(false);
+}
+}
+}
+// Do the access attribute propagation in combined index.
+// The goal of attribute propagation is internalization of readonly (RO)
+// or writeonly (WO) variables. To determine which variables are RO or WO
+// and which are not we take following steps:
+// - During analysis we speculatively assign readonly and writeonly
+//   attribute to all variables which can be internalized. When computing
+//   function summary we also assign readonly or writeonly attribute to a
+//   reference if function doesn't modify referenced variable (readonly)
+//   or doesn't read it (writeonly).
+//
+// - After computing dead symbols in combined index we do the attribute
+//   propagation. During this step we:
+//   a. clear RO and WO attributes from variables which are preserved or
+//      can't be imported
+//   b. clear RO and WO attributes from variables referenced by any global
+//      variable initializer
+//   c. clear RO attribute from variable referenced by a function when
+//      reference is not readonly
+//   d. clear WO attribute from variable referenced by a function when
+//      reference is not writeonly
+//
+//   Because of (c, d) we don't internalize variables read by function A
+//   and modified by function B.
+//
+// Internalization itself happens in the backend after import is finished
+// See internalizeGVsAfterImport.
+void ModuleSummaryIndex::propagateAttributes(
+const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols) {
+if (!PropagateAttrs)
+return;
+for (auto &P : *this)
+for (auto &S : P.second.SummaryList) {
+if (!isGlobalValueLive(S.get()))
+// We don't examine references from dead objects
+continue;
+// Global variable can't be marked read/writeonly if it is not eligible
+// to import since we need to ensure that all external references get
+// a local (imported) copy. It also can't be marked read/writeonly if
+// it or any alias (since alias points to the same memory) are preserved
+// or notEligibleToImport, since either of those means there could be
+// writes (or reads in case of writeonly) that are not visible (because
+// preserved means it could have external to DSO writes or reads, and
+// notEligibleToImport means it could have writes or reads via inline
+// assembly leading it to be in the @llvm.*used).
+if (auto *GVS = dyn_cast<GlobalVarSummary>(S->getBaseObject()))
+// Here we intentionally pass S.get() not GVS, because S could be
+// an alias. We don't analyze references here, because we have to
+// know exactly if GV is readonly to do so.
+if (!canImportGlobalVar(S.get(), /* AnalyzeRefs */ false) ||
+GUIDPreservedSymbols.count(P.first)) {
+GVS->setReadOnly(false);
+GVS->setWriteOnly(false);
+}
+propagateAttributesToRefs(S.get());
+}
+setWithAttributePropagation();
+if (llvm::AreStatisticsEnabled())
+for (auto &P : *this)
+if (P.second.SummaryList.size())
+if (auto *GVS = dyn_cast<GlobalVarSummary>(
+P.second.SummaryList[0]->getBaseObject()))
+if (isGlobalValueLive(GVS)) {
+if (GVS->maybeReadOnly())
+ReadOnlyLiveGVars++;
+if (GVS->maybeWriteOnly())
+WriteOnlyLiveGVars++;
+}
+}
+bool ModuleSummaryIndex::canImportGlobalVar(GlobalValueSummary *S,
+bool AnalyzeRefs) const {
+auto HasRefsPreventingImport = [this](const GlobalVarSummary *GVS) {
+// We don't analyze GV references during attribute propagation, so
+// GV with non-trivial initializer can be marked either read or
+// write-only.
+// Importing definiton of readonly GV with non-trivial initializer
+// allows us doing some extra optimizations (like converting indirect
+// calls to direct).
+// Definition of writeonly GV with non-trivial initializer should also
+// be imported. Not doing so will result in:
+// a) GV internalization in source module (because it's writeonly)
+// b) Importing of GV declaration to destination module as a result
+//    of promotion.
+// c) Link error (external declaration with internal definition).
+// However we do not promote objects referenced by writeonly GV
+// initializer by means of converting it to 'zeroinitializer'
+return !(ImportConstantsWithRefs && GVS->isConstant()) &&
+!isReadOnly(GVS) && !isWriteOnly(GVS) && GVS->refs().size();
+};
+auto *GVS = cast<GlobalVarSummary>(S->getBaseObject());
+// Global variable with non-trivial initializer can be imported
+// if it's readonly. This gives us extra opportunities for constant
+// folding and converting indirect calls to direct calls. We don't
+// analyze GV references during attribute propagation, because we
+// don't know yet if it is readonly or not.
+return !GlobalValue::isInterposableLinkage(S->linkage()) &&
+!S->notEligibleToImport() &&
+(!AnalyzeRefs || !HasRefsPreventingImport(GVS));
+}
+// TODO: write a graphviz dumper for SCCs (see ModuleSummaryIndex::exportToDot)
+// then delete this function and update its tests
+LLVM_DUMP_METHOD
+void ModuleSummaryIndex::dumpSCCs(raw_ostream &O) {
+for (scc_iterator<ModuleSummaryIndex *> I =
+scc_begin<ModuleSummaryIndex *>(this);
+!I.isAtEnd(); ++I) {
+O << "SCC (" << utostr(I->size()) << " node" << (I->size() == 1 ? "" : "s")
+<< ") {\n";
+for (const ValueInfo &V : *I) {
+FunctionSummary *F = nullptr;
+if (V.getSummaryList().size())
+F = cast<FunctionSummary>(V.getSummaryList().front().get());
+O << " " << (F == nullptr ? "External" : "") << " " << utostr(V.getGUID())
+<< (I.hasLoop() ? " (has loop)" : "") << "\n";
+}
+O << "}\n";
+}
+}
+namespace {
+struct Attributes {
+void add(const Twine &Name, const Twine &Value,
+const Twine &Comment = Twine());
+void addComment(const Twine &Comment);
+std::string getAsString() const;
+std::vector<std::string> Attrs;
+std::string Comments;
+};
+struct Edge {
+uint64_t SrcMod;
+int Hotness;
+GlobalValue::GUID Src;
+GlobalValue::GUID Dst;
+};
+}
+void Attributes::add(const Twine &Name, const Twine &Value,
+const Twine &Comment) {
+std::string A = Name.str();
+A += "=\"";
+A += Value.str();
+A += "\"";
+Attrs.push_back(A);
+addComment(Comment);
+}
+void Attributes::addComment(const Twine &Comment) {
+if (!Comment.isTriviallyEmpty()) {
+if (Comments.empty())
+Comments = " // ";
+else
+Comments += ", ";
+Comments += Comment.str();
+}
+}
+std::string Attributes::getAsString() const {
+if (Attrs.empty())
+return "";
+std::string Ret = "[";
+for (auto &A : Attrs)
+Ret += A + ",";
+Ret.pop_back();
+Ret += "];";
+Ret += Comments;
+return Ret;
+}
+static std::string linkageToString(GlobalValue::LinkageTypes LT) {
+switch (LT) {
+case GlobalValue::ExternalLinkage:
+return "extern";
+case GlobalValue::AvailableExternallyLinkage:
+return "av_ext";
+case GlobalValue::LinkOnceAnyLinkage:
+return "linkonce";
+case GlobalValue::LinkOnceODRLinkage:
+return "linkonce_odr";
+case GlobalValue::WeakAnyLinkage:
+return "weak";
+case GlobalValue::WeakODRLinkage:
+return "weak_odr";
+case GlobalValue::AppendingLinkage:
+return "appending";
+case GlobalValue::InternalLinkage:
+return "internal";
+case GlobalValue::PrivateLinkage:
+return "private";
+case GlobalValue::ExternalWeakLinkage:
+return "extern_weak";
+case GlobalValue::CommonLinkage:
+return "common";
+}
+return "<unknown>";
+}
+static std::string fflagsToString(FunctionSummary::FFlags F) {
+auto FlagValue = [](unsigned V) { return V ? '1' : '0'; };
+char FlagRep[] = {FlagValue(F.ReadNone),     FlagValue(F.ReadOnly),
+FlagValue(F.NoRecurse),    FlagValue(F.ReturnDoesNotAlias),
+FlagValue(F.NoInline), FlagValue(F.AlwaysInline), 0};
+return FlagRep;
+}
+// Get string representation of function instruction count and flags.
+static std::string getSummaryAttributes(GlobalValueSummary* GVS) {
+auto *FS = dyn_cast_or_null<FunctionSummary>(GVS);
+if (!FS)
+return "";
+return std::string("inst: ") + std::to_string(FS->instCount()) +
+", ffl: " + fflagsToString(FS->fflags());
+}
+static std::string getNodeVisualName(GlobalValue::GUID Id) {
+return std::string("@") + std::to_string(Id);
+}
+static std::string getNodeVisualName(const ValueInfo &VI) {
+return VI.name().empty() ? getNodeVisualName(VI.getGUID()) : VI.name().str();
+}
+static std::string getNodeLabel(const ValueInfo &VI, GlobalValueSummary *GVS) {
+if (isa<AliasSummary>(GVS))
+return getNodeVisualName(VI);
+std::string Attrs = getSummaryAttributes(GVS);
+std::string Label =
+getNodeVisualName(VI) + "|" + linkageToString(GVS->linkage());
+if (!Attrs.empty())
+Label += std::string(" (") + Attrs + ")";
+Label += "}";
+return Label;
+}
+// Write definition of external node, which doesn't have any
+// specific module associated with it. Typically this is function
+// or variable defined in native object or library.
+static void defineExternalNode(raw_ostream &OS, const char *Pfx,
+const ValueInfo &VI, GlobalValue::GUID Id) {
+auto StrId = std::to_string(Id);
+OS << "  " << StrId << " [label=\"";
+if (VI) {
+OS << getNodeVisualName(VI);
+} else {
+OS << getNodeVisualName(Id);
+}
+OS << "\"]; // defined externally\n";
+}
+static bool hasReadOnlyFlag(const GlobalValueSummary *S) {
+if (auto *GVS = dyn_cast<GlobalVarSummary>(S))
+return GVS->maybeReadOnly();
+return false;
+}
+static bool hasWriteOnlyFlag(const GlobalValueSummary *S) {
+if (auto *GVS = dyn_cast<GlobalVarSummary>(S))
+return GVS->maybeWriteOnly();
+return false;
+}
+static bool hasConstantFlag(const GlobalValueSummary *S) {
+if (auto *GVS = dyn_cast<GlobalVarSummary>(S))
+return GVS->isConstant();
+return false;
+}
+void ModuleSummaryIndex::exportToDot(
+raw_ostream &OS,
+const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols) const {
+std::vector<Edge> CrossModuleEdges;
+DenseMap<GlobalValue::GUID, std::vector<uint64_t>> NodeMap;
+using GVSOrderedMapTy = std::map<GlobalValue::GUID, GlobalValueSummary *>;
+std::map<StringRef, GVSOrderedMapTy> ModuleToDefinedGVS;
+collectDefinedGVSummariesPerModule(ModuleToDefinedGVS);
+// Get node identifier in form MXXX_<GUID>. The MXXX prefix is required,
+// because we may have multiple linkonce functions summaries.
+auto NodeId = [](uint64_t ModId, GlobalValue::GUID Id) {
+return ModId == (uint64_t)-1 ? std::to_string(Id)
+: std::string("M") + std::to_string(ModId) +
+"_" + std::to_string(Id);
+};
+auto DrawEdge = [&](const char *Pfx, uint64_t SrcMod, GlobalValue::GUID SrcId,
+uint64_t DstMod, GlobalValue::GUID DstId,
+int TypeOrHotness) {
+// 0 - alias
+// 1 - reference
+// 2 - constant reference
+// 3 - writeonly reference
+// Other value: (hotness - 4).
+TypeOrHotness += 4;
+static const char *EdgeAttrs[] = {
+" [style=dotted]; // alias",
+" [style=dashed]; // ref",
+" [style=dashed,color=forestgreen]; // const-ref",
+" [style=dashed,color=violetred]; // writeOnly-ref",
+" // call (hotness : Unknown)",
+" [color=blue]; // call (hotness : Cold)",
+" // call (hotness : None)",
+" [color=brown]; // call (hotness : Hot)",
+" [style=bold,color=red]; // call (hotness : Critical)"};
+assert(static_cast<size_t>(TypeOrHotness) <
+sizeof(EdgeAttrs) / sizeof(EdgeAttrs[0]));
+OS << Pfx << NodeId(SrcMod, SrcId) << " -> " << NodeId(DstMod, DstId)
+<< EdgeAttrs[TypeOrHotness] << "\n";
+};
+OS << "digraph Summary {\n";
+for (auto &ModIt : ModuleToDefinedGVS) {
+auto ModId = getModuleId(ModIt.first);
+OS << "  // Module: " << ModIt.first << "\n";
+OS << "  subgraph cluster_" << std::to_string(ModId) << " {\n";
+OS << "    style = filled;\n";
+OS << "    color = lightgrey;\n";
+OS << "    label = \"" << sys::path::filename(ModIt.first) << "\";\n";
+OS << "    node [style=filled,fillcolor=lightblue];\n";
+auto &GVSMap = ModIt.second;
+auto Draw = [&](GlobalValue::GUID IdFrom, GlobalValue::GUID IdTo, int Hotness) {
+if (!GVSMap.count(IdTo)) {
+CrossModuleEdges.push_back({ModId, Hotness, IdFrom, IdTo});
+return;
+}
+DrawEdge("    ", ModId, IdFrom, ModId, IdTo, Hotness);
+};
+for (auto &SummaryIt : GVSMap) {
+NodeMap[SummaryIt.first].push_back(ModId);
+auto Flags = SummaryIt.second->flags();
+Attributes A;
+if (isa<FunctionSummary>(SummaryIt.second)) {
+A.add("shape", "record", "function");
+} else if (isa<AliasSummary>(SummaryIt.second)) {
+A.add("style", "dotted,filled", "alias");
+A.add("shape", "box");
+} else {
+A.add("shape", "Mrecord", "variable");
+if (Flags.Live && hasReadOnlyFlag(SummaryIt.second))
+A.addComment("immutable");
+if (Flags.Live && hasWriteOnlyFlag(SummaryIt.second))
+A.addComment("writeOnly");
+if (Flags.Live && hasConstantFlag(SummaryIt.second))
+A.addComment("constant");
+}
+if (Flags.DSOLocal)
+A.addComment("dsoLocal");
+if (Flags.CanAutoHide)
+A.addComment("canAutoHide");
+if (GUIDPreservedSymbols.count(SummaryIt.first))
+A.addComment("preserved");
+auto VI = getValueInfo(SummaryIt.first);
+A.add("label", getNodeLabel(VI, SummaryIt.second));
+if (!Flags.Live)
+A.add("fillcolor", "red", "dead");
+else if (Flags.NotEligibleToImport)
+A.add("fillcolor", "yellow", "not eligible to import");
+OS << "    " << NodeId(ModId, SummaryIt.first) << " " << A.getAsString()
+<< "\n";
+}
+OS << "    // Edges:\n";
+for (auto &SummaryIt : GVSMap) {
+auto *GVS = SummaryIt.second;
+for (auto &R : GVS->refs())
+Draw(SummaryIt.first, R.getGUID(),
+R.isWriteOnly() ? -1 : (R.isReadOnly() ? -2 : -3));
+if (auto *AS = dyn_cast_or_null<AliasSummary>(SummaryIt.second)) {
+Draw(SummaryIt.first, AS->getAliaseeGUID(), -4);
+continue;
+}
+if (auto *FS = dyn_cast_or_null<FunctionSummary>(SummaryIt.second))
+for (auto &CGEdge : FS->calls())
+Draw(SummaryIt.first, CGEdge.first.getGUID(),
+static_cast<int>(CGEdge.second.Hotness));
+}
+OS << "  }\n";
+}
+OS << "  // Cross-module edges:\n";
+for (auto &E : CrossModuleEdges) {
+auto &ModList = NodeMap[E.Dst];
+if (ModList.empty()) {
+defineExternalNode(OS, "  ", getValueInfo(E.Dst), E.Dst);
+// Add fake module to the list to draw an edge to an external node
+// in the loop below.
+ModList.push_back(-1);
+}
+for (auto DstMod : ModList)
+// The edge representing call or ref is drawn to every module where target
+// symbol is defined. When target is a linkonce symbol there can be
+// multiple edges representing a single call or ref, both intra-module and
+// cross-module. As we've already drawn all intra-module edges before we
+// skip it here.
+if (DstMod != E.SrcMod)
+DrawEdge("  ", E.SrcMod, E.Src, DstMod, E.Dst, E.Hotness);
+}
+OS << "}";
+}

Mercurial > hg > CbC > CbC_llvm

comparison llvm/lib/IR/ModuleSummaryIndex.cpp @ 150:1d019706d866