| //===- ModuleSummaryAnalysis.cpp - Module summary index builder -----------===// |
| // |
| // 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 pass builds a ModuleSummaryIndex object for the module, to be written |
| // to bitcode or LLVM assembly. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Analysis/ModuleSummaryAnalysis.h" |
| #include "llvm/ADT/ArrayRef.h" |
| #include "llvm/ADT/DenseSet.h" |
| #include "llvm/ADT/MapVector.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/SetVector.h" |
| #include "llvm/ADT/SmallPtrSet.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/StringRef.h" |
| #include "llvm/Analysis/BlockFrequencyInfo.h" |
| #include "llvm/Analysis/BranchProbabilityInfo.h" |
| #include "llvm/Analysis/IndirectCallPromotionAnalysis.h" |
| #include "llvm/Analysis/LoopInfo.h" |
| #include "llvm/Analysis/ProfileSummaryInfo.h" |
| #include "llvm/Analysis/StackSafetyAnalysis.h" |
| #include "llvm/Analysis/TypeMetadataUtils.h" |
| #include "llvm/IR/Attributes.h" |
| #include "llvm/IR/BasicBlock.h" |
| #include "llvm/IR/Constant.h" |
| #include "llvm/IR/Constants.h" |
| #include "llvm/IR/Dominators.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/IR/GlobalAlias.h" |
| #include "llvm/IR/GlobalValue.h" |
| #include "llvm/IR/GlobalVariable.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/IntrinsicInst.h" |
| #include "llvm/IR/Intrinsics.h" |
| #include "llvm/IR/Metadata.h" |
| #include "llvm/IR/Module.h" |
| #include "llvm/IR/ModuleSummaryIndex.h" |
| #include "llvm/IR/Use.h" |
| #include "llvm/IR/User.h" |
| #include "llvm/InitializePasses.h" |
| #include "llvm/Object/ModuleSymbolTable.h" |
| #include "llvm/Object/SymbolicFile.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Support/Casting.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/FileSystem.h" |
| #include <algorithm> |
| #include <cassert> |
| #include <cstdint> |
| #include <vector> |
| |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "module-summary-analysis" |
| |
| // Option to force edges cold which will block importing when the |
| // -import-cold-multiplier is set to 0. Useful for debugging. |
| FunctionSummary::ForceSummaryHotnessType ForceSummaryEdgesCold = |
| FunctionSummary::FSHT_None; |
| cl::opt<FunctionSummary::ForceSummaryHotnessType, true> FSEC( |
| "force-summary-edges-cold", cl::Hidden, cl::location(ForceSummaryEdgesCold), |
| cl::desc("Force all edges in the function summary to cold"), |
| cl::values(clEnumValN(FunctionSummary::FSHT_None, "none", "None."), |
| clEnumValN(FunctionSummary::FSHT_AllNonCritical, |
| "all-non-critical", "All non-critical edges."), |
| clEnumValN(FunctionSummary::FSHT_All, "all", "All edges."))); |
| |
| cl::opt<std::string> ModuleSummaryDotFile( |
| "module-summary-dot-file", cl::init(""), cl::Hidden, |
| cl::value_desc("filename"), |
| cl::desc("File to emit dot graph of new summary into.")); |
| |
| // Walk through the operands of a given User via worklist iteration and populate |
| // the set of GlobalValue references encountered. Invoked either on an |
| // Instruction or a GlobalVariable (which walks its initializer). |
| // Return true if any of the operands contains blockaddress. This is important |
| // to know when computing summary for global var, because if global variable |
| // references basic block address we can't import it separately from function |
| // containing that basic block. For simplicity we currently don't import such |
| // global vars at all. When importing function we aren't interested if any |
| // instruction in it takes an address of any basic block, because instruction |
| // can only take an address of basic block located in the same function. |
| static bool findRefEdges(ModuleSummaryIndex &Index, const User *CurUser, |
| SetVector<ValueInfo> &RefEdges, |
| SmallPtrSet<const User *, 8> &Visited) { |
| bool HasBlockAddress = false; |
| SmallVector<const User *, 32> Worklist; |
| if (Visited.insert(CurUser).second) |
| Worklist.push_back(CurUser); |
| |
| while (!Worklist.empty()) { |
| const User *U = Worklist.pop_back_val(); |
| const auto *CB = dyn_cast<CallBase>(U); |
| |
| for (const auto &OI : U->operands()) { |
| const User *Operand = dyn_cast<User>(OI); |
| if (!Operand) |
| continue; |
| if (isa<BlockAddress>(Operand)) { |
| HasBlockAddress = true; |
| continue; |
| } |
| if (auto *GV = dyn_cast<GlobalValue>(Operand)) { |
| // We have a reference to a global value. This should be added to |
| // the reference set unless it is a callee. Callees are handled |
| // specially by WriteFunction and are added to a separate list. |
| if (!(CB && CB->isCallee(&OI))) |
| RefEdges.insert(Index.getOrInsertValueInfo(GV)); |
| continue; |
| } |
| if (Visited.insert(Operand).second) |
| Worklist.push_back(Operand); |
| } |
| } |
| return HasBlockAddress; |
| } |
| |
| static CalleeInfo::HotnessType getHotness(uint64_t ProfileCount, |
| ProfileSummaryInfo *PSI) { |
| if (!PSI) |
| return CalleeInfo::HotnessType::Unknown; |
| if (PSI->isHotCount(ProfileCount)) |
| return CalleeInfo::HotnessType::Hot; |
| if (PSI->isColdCount(ProfileCount)) |
| return CalleeInfo::HotnessType::Cold; |
| return CalleeInfo::HotnessType::None; |
| } |
| |
| static bool isNonRenamableLocal(const GlobalValue &GV) { |
| return GV.hasSection() && GV.hasLocalLinkage(); |
| } |
| |
| /// Determine whether this call has all constant integer arguments (excluding |
| /// "this") and summarize it to VCalls or ConstVCalls as appropriate. |
| static void addVCallToSet(DevirtCallSite Call, GlobalValue::GUID Guid, |
| SetVector<FunctionSummary::VFuncId> &VCalls, |
| SetVector<FunctionSummary::ConstVCall> &ConstVCalls) { |
| std::vector<uint64_t> Args; |
| // Start from the second argument to skip the "this" pointer. |
| for (auto &Arg : drop_begin(Call.CB.args())) { |
| auto *CI = dyn_cast<ConstantInt>(Arg); |
| if (!CI || CI->getBitWidth() > 64) { |
| VCalls.insert({Guid, Call.Offset}); |
| return; |
| } |
| Args.push_back(CI->getZExtValue()); |
| } |
| ConstVCalls.insert({{Guid, Call.Offset}, std::move(Args)}); |
| } |
| |
| /// If this intrinsic call requires that we add information to the function |
| /// summary, do so via the non-constant reference arguments. |
| static void addIntrinsicToSummary( |
| const CallInst *CI, SetVector<GlobalValue::GUID> &TypeTests, |
| SetVector<FunctionSummary::VFuncId> &TypeTestAssumeVCalls, |
| SetVector<FunctionSummary::VFuncId> &TypeCheckedLoadVCalls, |
| SetVector<FunctionSummary::ConstVCall> &TypeTestAssumeConstVCalls, |
| SetVector<FunctionSummary::ConstVCall> &TypeCheckedLoadConstVCalls, |
| DominatorTree &DT) { |
| switch (CI->getCalledFunction()->getIntrinsicID()) { |
| case Intrinsic::type_test: { |
| auto *TypeMDVal = cast<MetadataAsValue>(CI->getArgOperand(1)); |
| auto *TypeId = dyn_cast<MDString>(TypeMDVal->getMetadata()); |
| if (!TypeId) |
| break; |
| GlobalValue::GUID Guid = GlobalValue::getGUID(TypeId->getString()); |
| |
| // Produce a summary from type.test intrinsics. We only summarize type.test |
| // intrinsics that are used other than by an llvm.assume intrinsic. |
| // Intrinsics that are assumed are relevant only to the devirtualization |
| // pass, not the type test lowering pass. |
| bool HasNonAssumeUses = llvm::any_of(CI->uses(), [](const Use &CIU) { |
| return !isa<AssumeInst>(CIU.getUser()); |
| }); |
| if (HasNonAssumeUses) |
| TypeTests.insert(Guid); |
| |
| SmallVector<DevirtCallSite, 4> DevirtCalls; |
| SmallVector<CallInst *, 4> Assumes; |
| findDevirtualizableCallsForTypeTest(DevirtCalls, Assumes, CI, DT); |
| for (auto &Call : DevirtCalls) |
| addVCallToSet(Call, Guid, TypeTestAssumeVCalls, |
| TypeTestAssumeConstVCalls); |
| |
| break; |
| } |
| |
| case Intrinsic::type_checked_load: { |
| auto *TypeMDVal = cast<MetadataAsValue>(CI->getArgOperand(2)); |
| auto *TypeId = dyn_cast<MDString>(TypeMDVal->getMetadata()); |
| if (!TypeId) |
| break; |
| GlobalValue::GUID Guid = GlobalValue::getGUID(TypeId->getString()); |
| |
| SmallVector<DevirtCallSite, 4> DevirtCalls; |
| SmallVector<Instruction *, 4> LoadedPtrs; |
| SmallVector<Instruction *, 4> Preds; |
| bool HasNonCallUses = false; |
| findDevirtualizableCallsForTypeCheckedLoad(DevirtCalls, LoadedPtrs, Preds, |
| HasNonCallUses, CI, DT); |
| // Any non-call uses of the result of llvm.type.checked.load will |
| // prevent us from optimizing away the llvm.type.test. |
| if (HasNonCallUses) |
| TypeTests.insert(Guid); |
| for (auto &Call : DevirtCalls) |
| addVCallToSet(Call, Guid, TypeCheckedLoadVCalls, |
| TypeCheckedLoadConstVCalls); |
| |
| break; |
| } |
| default: |
| break; |
| } |
| } |
| |
| static bool isNonVolatileLoad(const Instruction *I) { |
| if (const auto *LI = dyn_cast<LoadInst>(I)) |
| return !LI->isVolatile(); |
| |
| return false; |
| } |
| |
| static bool isNonVolatileStore(const Instruction *I) { |
| if (const auto *SI = dyn_cast<StoreInst>(I)) |
| return !SI->isVolatile(); |
| |
| return false; |
| } |
| |
| static void computeFunctionSummary( |
| ModuleSummaryIndex &Index, const Module &M, const Function &F, |
| BlockFrequencyInfo *BFI, ProfileSummaryInfo *PSI, DominatorTree &DT, |
| bool HasLocalsInUsedOrAsm, DenseSet<GlobalValue::GUID> &CantBePromoted, |
| bool IsThinLTO, |
| std::function<const StackSafetyInfo *(const Function &F)> GetSSICallback) { |
| // Summary not currently supported for anonymous functions, they should |
| // have been named. |
| assert(F.hasName()); |
| |
| unsigned NumInsts = 0; |
| // Map from callee ValueId to profile count. Used to accumulate profile |
| // counts for all static calls to a given callee. |
| MapVector<ValueInfo, CalleeInfo> CallGraphEdges; |
| SetVector<ValueInfo> RefEdges, LoadRefEdges, StoreRefEdges; |
| SetVector<GlobalValue::GUID> TypeTests; |
| SetVector<FunctionSummary::VFuncId> TypeTestAssumeVCalls, |
| TypeCheckedLoadVCalls; |
| SetVector<FunctionSummary::ConstVCall> TypeTestAssumeConstVCalls, |
| TypeCheckedLoadConstVCalls; |
| ICallPromotionAnalysis ICallAnalysis; |
| SmallPtrSet<const User *, 8> Visited; |
| |
| // Add personality function, prefix data and prologue data to function's ref |
| // list. |
| findRefEdges(Index, &F, RefEdges, Visited); |
| std::vector<const Instruction *> NonVolatileLoads; |
| std::vector<const Instruction *> NonVolatileStores; |
| |
| bool HasInlineAsmMaybeReferencingInternal = false; |
| bool HasIndirBranchToBlockAddress = false; |
| bool HasUnknownCall = false; |
| bool MayThrow = false; |
| for (const BasicBlock &BB : F) { |
| // We don't allow inlining of function with indirect branch to blockaddress. |
| // If the blockaddress escapes the function, e.g., via a global variable, |
| // inlining may lead to an invalid cross-function reference. So we shouldn't |
| // import such function either. |
| if (BB.hasAddressTaken()) { |
| for (User *U : BlockAddress::get(const_cast<BasicBlock *>(&BB))->users()) |
| if (!isa<CallBrInst>(*U)) { |
| HasIndirBranchToBlockAddress = true; |
| break; |
| } |
| } |
| |
| for (const Instruction &I : BB) { |
| if (I.isDebugOrPseudoInst()) |
| continue; |
| ++NumInsts; |
| |
| // Regular LTO module doesn't participate in ThinLTO import, |
| // so no reference from it can be read/writeonly, since this |
| // would require importing variable as local copy |
| if (IsThinLTO) { |
| if (isNonVolatileLoad(&I)) { |
| // Postpone processing of non-volatile load instructions |
| // See comments below |
| Visited.insert(&I); |
| NonVolatileLoads.push_back(&I); |
| continue; |
| } else if (isNonVolatileStore(&I)) { |
| Visited.insert(&I); |
| NonVolatileStores.push_back(&I); |
| // All references from second operand of store (destination address) |
| // can be considered write-only if they're not referenced by any |
| // non-store instruction. References from first operand of store |
| // (stored value) can't be treated either as read- or as write-only |
| // so we add them to RefEdges as we do with all other instructions |
| // except non-volatile load. |
| Value *Stored = I.getOperand(0); |
| if (auto *GV = dyn_cast<GlobalValue>(Stored)) |
| // findRefEdges will try to examine GV operands, so instead |
| // of calling it we should add GV to RefEdges directly. |
| RefEdges.insert(Index.getOrInsertValueInfo(GV)); |
| else if (auto *U = dyn_cast<User>(Stored)) |
| findRefEdges(Index, U, RefEdges, Visited); |
| continue; |
| } |
| } |
| findRefEdges(Index, &I, RefEdges, Visited); |
| const auto *CB = dyn_cast<CallBase>(&I); |
| if (!CB) { |
| if (I.mayThrow()) |
| MayThrow = true; |
| continue; |
| } |
| |
| const auto *CI = dyn_cast<CallInst>(&I); |
| // Since we don't know exactly which local values are referenced in inline |
| // assembly, conservatively mark the function as possibly referencing |
| // a local value from inline assembly to ensure we don't export a |
| // reference (which would require renaming and promotion of the |
| // referenced value). |
| if (HasLocalsInUsedOrAsm && CI && CI->isInlineAsm()) |
| HasInlineAsmMaybeReferencingInternal = true; |
| |
| auto *CalledValue = CB->getCalledOperand(); |
| auto *CalledFunction = CB->getCalledFunction(); |
| if (CalledValue && !CalledFunction) { |
| CalledValue = CalledValue->stripPointerCasts(); |
| // Stripping pointer casts can reveal a called function. |
| CalledFunction = dyn_cast<Function>(CalledValue); |
| } |
| // Check if this is an alias to a function. If so, get the |
| // called aliasee for the checks below. |
| if (auto *GA = dyn_cast<GlobalAlias>(CalledValue)) { |
| assert(!CalledFunction && "Expected null called function in callsite for alias"); |
| CalledFunction = dyn_cast<Function>(GA->getAliaseeObject()); |
| } |
| // Check if this is a direct call to a known function or a known |
| // intrinsic, or an indirect call with profile data. |
| if (CalledFunction) { |
| if (CI && CalledFunction->isIntrinsic()) { |
| addIntrinsicToSummary( |
| CI, TypeTests, TypeTestAssumeVCalls, TypeCheckedLoadVCalls, |
| TypeTestAssumeConstVCalls, TypeCheckedLoadConstVCalls, DT); |
| continue; |
| } |
| // We should have named any anonymous globals |
| assert(CalledFunction->hasName()); |
| auto ScaledCount = PSI->getProfileCount(*CB, BFI); |
| auto Hotness = ScaledCount ? getHotness(ScaledCount.getValue(), PSI) |
| : CalleeInfo::HotnessType::Unknown; |
| if (ForceSummaryEdgesCold != FunctionSummary::FSHT_None) |
| Hotness = CalleeInfo::HotnessType::Cold; |
| |
| // Use the original CalledValue, in case it was an alias. We want |
| // to record the call edge to the alias in that case. Eventually |
| // an alias summary will be created to associate the alias and |
| // aliasee. |
| auto &ValueInfo = CallGraphEdges[Index.getOrInsertValueInfo( |
| cast<GlobalValue>(CalledValue))]; |
| ValueInfo.updateHotness(Hotness); |
| // Add the relative block frequency to CalleeInfo if there is no profile |
| // information. |
| if (BFI != nullptr && Hotness == CalleeInfo::HotnessType::Unknown) { |
| uint64_t BBFreq = BFI->getBlockFreq(&BB).getFrequency(); |
| uint64_t EntryFreq = BFI->getEntryFreq(); |
| ValueInfo.updateRelBlockFreq(BBFreq, EntryFreq); |
| } |
| } else { |
| HasUnknownCall = true; |
| // Skip inline assembly calls. |
| if (CI && CI->isInlineAsm()) |
| continue; |
| // Skip direct calls. |
| if (!CalledValue || isa<Constant>(CalledValue)) |
| continue; |
| |
| // Check if the instruction has a callees metadata. If so, add callees |
| // to CallGraphEdges to reflect the references from the metadata, and |
| // to enable importing for subsequent indirect call promotion and |
| // inlining. |
| if (auto *MD = I.getMetadata(LLVMContext::MD_callees)) { |
| for (auto &Op : MD->operands()) { |
| Function *Callee = mdconst::extract_or_null<Function>(Op); |
| if (Callee) |
| CallGraphEdges[Index.getOrInsertValueInfo(Callee)]; |
| } |
| } |
| |
| uint32_t NumVals, NumCandidates; |
| uint64_t TotalCount; |
| auto CandidateProfileData = |
| ICallAnalysis.getPromotionCandidatesForInstruction( |
| &I, NumVals, TotalCount, NumCandidates); |
| for (auto &Candidate : CandidateProfileData) |
| CallGraphEdges[Index.getOrInsertValueInfo(Candidate.Value)] |
| .updateHotness(getHotness(Candidate.Count, PSI)); |
| } |
| } |
| } |
| Index.addBlockCount(F.size()); |
| |
| std::vector<ValueInfo> Refs; |
| if (IsThinLTO) { |
| auto AddRefEdges = [&](const std::vector<const Instruction *> &Instrs, |
| SetVector<ValueInfo> &Edges, |
| SmallPtrSet<const User *, 8> &Cache) { |
| for (const auto *I : Instrs) { |
| Cache.erase(I); |
| findRefEdges(Index, I, Edges, Cache); |
| } |
| }; |
| |
| // By now we processed all instructions in a function, except |
| // non-volatile loads and non-volatile value stores. Let's find |
| // ref edges for both of instruction sets |
| AddRefEdges(NonVolatileLoads, LoadRefEdges, Visited); |
| // We can add some values to the Visited set when processing load |
| // instructions which are also used by stores in NonVolatileStores. |
| // For example this can happen if we have following code: |
| // |
| // store %Derived* @foo, %Derived** bitcast (%Base** @bar to %Derived**) |
| // %42 = load %Derived*, %Derived** bitcast (%Base** @bar to %Derived**) |
| // |
| // After processing loads we'll add bitcast to the Visited set, and if |
| // we use the same set while processing stores, we'll never see store |
| // to @bar and @bar will be mistakenly treated as readonly. |
| SmallPtrSet<const llvm::User *, 8> StoreCache; |
| AddRefEdges(NonVolatileStores, StoreRefEdges, StoreCache); |
| |
| // If both load and store instruction reference the same variable |
| // we won't be able to optimize it. Add all such reference edges |
| // to RefEdges set. |
| for (auto &VI : StoreRefEdges) |
| if (LoadRefEdges.remove(VI)) |
| RefEdges.insert(VI); |
| |
| unsigned RefCnt = RefEdges.size(); |
| // All new reference edges inserted in two loops below are either |
| // read or write only. They will be grouped in the end of RefEdges |
| // vector, so we can use a single integer value to identify them. |
| for (auto &VI : LoadRefEdges) |
| RefEdges.insert(VI); |
| |
| unsigned FirstWORef = RefEdges.size(); |
| for (auto &VI : StoreRefEdges) |
| RefEdges.insert(VI); |
| |
| Refs = RefEdges.takeVector(); |
| for (; RefCnt < FirstWORef; ++RefCnt) |
| Refs[RefCnt].setReadOnly(); |
| |
| for (; RefCnt < Refs.size(); ++RefCnt) |
| Refs[RefCnt].setWriteOnly(); |
| } else { |
| Refs = RefEdges.takeVector(); |
| } |
| // Explicit add hot edges to enforce importing for designated GUIDs for |
| // sample PGO, to enable the same inlines as the profiled optimized binary. |
| for (auto &I : F.getImportGUIDs()) |
| CallGraphEdges[Index.getOrInsertValueInfo(I)].updateHotness( |
| ForceSummaryEdgesCold == FunctionSummary::FSHT_All |
| ? CalleeInfo::HotnessType::Cold |
| : CalleeInfo::HotnessType::Critical); |
| |
| bool NonRenamableLocal = isNonRenamableLocal(F); |
| bool NotEligibleForImport = NonRenamableLocal || |
| HasInlineAsmMaybeReferencingInternal || |
| HasIndirBranchToBlockAddress; |
| GlobalValueSummary::GVFlags Flags( |
| F.getLinkage(), F.getVisibility(), NotEligibleForImport, |
| /* Live = */ false, F.isDSOLocal(), |
| F.hasLinkOnceODRLinkage() && F.hasGlobalUnnamedAddr()); |
| FunctionSummary::FFlags FunFlags{ |
| F.hasFnAttribute(Attribute::ReadNone), |
| F.hasFnAttribute(Attribute::ReadOnly), |
| F.hasFnAttribute(Attribute::NoRecurse), F.returnDoesNotAlias(), |
| // FIXME: refactor this to use the same code that inliner is using. |
| // Don't try to import functions with noinline attribute. |
| F.getAttributes().hasFnAttr(Attribute::NoInline), |
| F.hasFnAttribute(Attribute::AlwaysInline), |
| F.hasFnAttribute(Attribute::NoUnwind), MayThrow, HasUnknownCall}; |
| std::vector<FunctionSummary::ParamAccess> ParamAccesses; |
| if (auto *SSI = GetSSICallback(F)) |
| ParamAccesses = SSI->getParamAccesses(Index); |
| auto FuncSummary = std::make_unique<FunctionSummary>( |
| Flags, NumInsts, FunFlags, /*EntryCount=*/0, std::move(Refs), |
| CallGraphEdges.takeVector(), TypeTests.takeVector(), |
| TypeTestAssumeVCalls.takeVector(), TypeCheckedLoadVCalls.takeVector(), |
| TypeTestAssumeConstVCalls.takeVector(), |
| TypeCheckedLoadConstVCalls.takeVector(), std::move(ParamAccesses)); |
| if (NonRenamableLocal) |
| CantBePromoted.insert(F.getGUID()); |
| Index.addGlobalValueSummary(F, std::move(FuncSummary)); |
| } |
| |
| /// Find function pointers referenced within the given vtable initializer |
| /// (or subset of an initializer) \p I. The starting offset of \p I within |
| /// the vtable initializer is \p StartingOffset. Any discovered function |
| /// pointers are added to \p VTableFuncs along with their cumulative offset |
| /// within the initializer. |
| static void findFuncPointers(const Constant *I, uint64_t StartingOffset, |
| const Module &M, ModuleSummaryIndex &Index, |
| VTableFuncList &VTableFuncs) { |
| // First check if this is a function pointer. |
| if (I->getType()->isPointerTy()) { |
| auto Fn = dyn_cast<Function>(I->stripPointerCasts()); |
| // We can disregard __cxa_pure_virtual as a possible call target, as |
| // calls to pure virtuals are UB. |
| if (Fn && Fn->getName() != "__cxa_pure_virtual") |
| VTableFuncs.push_back({Index.getOrInsertValueInfo(Fn), StartingOffset}); |
| return; |
| } |
| |
| // Walk through the elements in the constant struct or array and recursively |
| // look for virtual function pointers. |
| const DataLayout &DL = M.getDataLayout(); |
| if (auto *C = dyn_cast<ConstantStruct>(I)) { |
| StructType *STy = dyn_cast<StructType>(C->getType()); |
| assert(STy); |
| const StructLayout *SL = DL.getStructLayout(C->getType()); |
| |
| for (auto EI : llvm::enumerate(STy->elements())) { |
| auto Offset = SL->getElementOffset(EI.index()); |
| unsigned Op = SL->getElementContainingOffset(Offset); |
| findFuncPointers(cast<Constant>(I->getOperand(Op)), |
| StartingOffset + Offset, M, Index, VTableFuncs); |
| } |
| } else if (auto *C = dyn_cast<ConstantArray>(I)) { |
| ArrayType *ATy = C->getType(); |
| Type *EltTy = ATy->getElementType(); |
| uint64_t EltSize = DL.getTypeAllocSize(EltTy); |
| for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i) { |
| findFuncPointers(cast<Constant>(I->getOperand(i)), |
| StartingOffset + i * EltSize, M, Index, VTableFuncs); |
| } |
| } |
| } |
| |
| // Identify the function pointers referenced by vtable definition \p V. |
| static void computeVTableFuncs(ModuleSummaryIndex &Index, |
| const GlobalVariable &V, const Module &M, |
| VTableFuncList &VTableFuncs) { |
| if (!V.isConstant()) |
| return; |
| |
| findFuncPointers(V.getInitializer(), /*StartingOffset=*/0, M, Index, |
| VTableFuncs); |
| |
| #ifndef NDEBUG |
| // Validate that the VTableFuncs list is ordered by offset. |
| uint64_t PrevOffset = 0; |
| for (auto &P : VTableFuncs) { |
| // The findVFuncPointers traversal should have encountered the |
| // functions in offset order. We need to use ">=" since PrevOffset |
| // starts at 0. |
| assert(P.VTableOffset >= PrevOffset); |
| PrevOffset = P.VTableOffset; |
| } |
| #endif |
| } |
| |
| /// Record vtable definition \p V for each type metadata it references. |
| static void |
| recordTypeIdCompatibleVtableReferences(ModuleSummaryIndex &Index, |
| const GlobalVariable &V, |
| SmallVectorImpl<MDNode *> &Types) { |
| for (MDNode *Type : Types) { |
| auto TypeID = Type->getOperand(1).get(); |
| |
| uint64_t Offset = |
| cast<ConstantInt>( |
| cast<ConstantAsMetadata>(Type->getOperand(0))->getValue()) |
| ->getZExtValue(); |
| |
| if (auto *TypeId = dyn_cast<MDString>(TypeID)) |
| Index.getOrInsertTypeIdCompatibleVtableSummary(TypeId->getString()) |
| .push_back({Offset, Index.getOrInsertValueInfo(&V)}); |
| } |
| } |
| |
| static void computeVariableSummary(ModuleSummaryIndex &Index, |
| const GlobalVariable &V, |
| DenseSet<GlobalValue::GUID> &CantBePromoted, |
| const Module &M, |
| SmallVectorImpl<MDNode *> &Types) { |
| SetVector<ValueInfo> RefEdges; |
| SmallPtrSet<const User *, 8> Visited; |
| bool HasBlockAddress = findRefEdges(Index, &V, RefEdges, Visited); |
| bool NonRenamableLocal = isNonRenamableLocal(V); |
| GlobalValueSummary::GVFlags Flags( |
| V.getLinkage(), V.getVisibility(), NonRenamableLocal, |
| /* Live = */ false, V.isDSOLocal(), |
| V.hasLinkOnceODRLinkage() && V.hasGlobalUnnamedAddr()); |
| |
| VTableFuncList VTableFuncs; |
| // If splitting is not enabled, then we compute the summary information |
| // necessary for index-based whole program devirtualization. |
| if (!Index.enableSplitLTOUnit()) { |
| Types.clear(); |
| V.getMetadata(LLVMContext::MD_type, Types); |
| if (!Types.empty()) { |
| // Identify the function pointers referenced by this vtable definition. |
| computeVTableFuncs(Index, V, M, VTableFuncs); |
| |
| // Record this vtable definition for each type metadata it references. |
| recordTypeIdCompatibleVtableReferences(Index, V, Types); |
| } |
| } |
| |
| // Don't mark variables we won't be able to internalize as read/write-only. |
| bool CanBeInternalized = |
| !V.hasComdat() && !V.hasAppendingLinkage() && !V.isInterposable() && |
| !V.hasAvailableExternallyLinkage() && !V.hasDLLExportStorageClass(); |
| bool Constant = V.isConstant(); |
| GlobalVarSummary::GVarFlags VarFlags(CanBeInternalized, |
| Constant ? false : CanBeInternalized, |
| Constant, V.getVCallVisibility()); |
| auto GVarSummary = std::make_unique<GlobalVarSummary>(Flags, VarFlags, |
| RefEdges.takeVector()); |
| if (NonRenamableLocal) |
| CantBePromoted.insert(V.getGUID()); |
| if (HasBlockAddress) |
| GVarSummary->setNotEligibleToImport(); |
| if (!VTableFuncs.empty()) |
| GVarSummary->setVTableFuncs(VTableFuncs); |
| Index.addGlobalValueSummary(V, std::move(GVarSummary)); |
| } |
| |
| static void |
| computeAliasSummary(ModuleSummaryIndex &Index, const GlobalAlias &A, |
| DenseSet<GlobalValue::GUID> &CantBePromoted) { |
| bool NonRenamableLocal = isNonRenamableLocal(A); |
| GlobalValueSummary::GVFlags Flags( |
| A.getLinkage(), A.getVisibility(), NonRenamableLocal, |
| /* Live = */ false, A.isDSOLocal(), |
| A.hasLinkOnceODRLinkage() && A.hasGlobalUnnamedAddr()); |
| auto AS = std::make_unique<AliasSummary>(Flags); |
| auto *Aliasee = A.getAliaseeObject(); |
| auto AliaseeVI = Index.getValueInfo(Aliasee->getGUID()); |
| assert(AliaseeVI && "Alias expects aliasee summary to be available"); |
| assert(AliaseeVI.getSummaryList().size() == 1 && |
| "Expected a single entry per aliasee in per-module index"); |
| AS->setAliasee(AliaseeVI, AliaseeVI.getSummaryList()[0].get()); |
| if (NonRenamableLocal) |
| CantBePromoted.insert(A.getGUID()); |
| Index.addGlobalValueSummary(A, std::move(AS)); |
| } |
| |
| // Set LiveRoot flag on entries matching the given value name. |
| static void setLiveRoot(ModuleSummaryIndex &Index, StringRef Name) { |
| if (ValueInfo VI = Index.getValueInfo(GlobalValue::getGUID(Name))) |
| for (auto &Summary : VI.getSummaryList()) |
| Summary->setLive(true); |
| } |
| |
| ModuleSummaryIndex llvm::buildModuleSummaryIndex( |
| const Module &M, |
| std::function<BlockFrequencyInfo *(const Function &F)> GetBFICallback, |
| ProfileSummaryInfo *PSI, |
| std::function<const StackSafetyInfo *(const Function &F)> GetSSICallback) { |
| assert(PSI); |
| bool EnableSplitLTOUnit = false; |
| if (auto *MD = mdconst::extract_or_null<ConstantInt>( |
| M.getModuleFlag("EnableSplitLTOUnit"))) |
| EnableSplitLTOUnit = MD->getZExtValue(); |
| ModuleSummaryIndex Index(/*HaveGVs=*/true, EnableSplitLTOUnit); |
| |
| // Identify the local values in the llvm.used and llvm.compiler.used sets, |
| // which should not be exported as they would then require renaming and |
| // promotion, but we may have opaque uses e.g. in inline asm. We collect them |
| // here because we use this information to mark functions containing inline |
| // assembly calls as not importable. |
| SmallPtrSet<GlobalValue *, 4> LocalsUsed; |
| SmallVector<GlobalValue *, 4> Used; |
| // First collect those in the llvm.used set. |
| collectUsedGlobalVariables(M, Used, /*CompilerUsed=*/false); |
| // Next collect those in the llvm.compiler.used set. |
| collectUsedGlobalVariables(M, Used, /*CompilerUsed=*/true); |
| DenseSet<GlobalValue::GUID> CantBePromoted; |
| for (auto *V : Used) { |
| if (V->hasLocalLinkage()) { |
| LocalsUsed.insert(V); |
| CantBePromoted.insert(V->getGUID()); |
| } |
| } |
| |
| bool HasLocalInlineAsmSymbol = false; |
| if (!M.getModuleInlineAsm().empty()) { |
| // Collect the local values defined by module level asm, and set up |
| // summaries for these symbols so that they can be marked as NoRename, |
| // to prevent export of any use of them in regular IR that would require |
| // renaming within the module level asm. Note we don't need to create a |
| // summary for weak or global defs, as they don't need to be flagged as |
| // NoRename, and defs in module level asm can't be imported anyway. |
| // Also, any values used but not defined within module level asm should |
| // be listed on the llvm.used or llvm.compiler.used global and marked as |
| // referenced from there. |
| ModuleSymbolTable::CollectAsmSymbols( |
| M, [&](StringRef Name, object::BasicSymbolRef::Flags Flags) { |
| // Symbols not marked as Weak or Global are local definitions. |
| if (Flags & (object::BasicSymbolRef::SF_Weak | |
| object::BasicSymbolRef::SF_Global)) |
| return; |
| HasLocalInlineAsmSymbol = true; |
| GlobalValue *GV = M.getNamedValue(Name); |
| if (!GV) |
| return; |
| assert(GV->isDeclaration() && "Def in module asm already has definition"); |
| GlobalValueSummary::GVFlags GVFlags( |
| GlobalValue::InternalLinkage, GlobalValue::DefaultVisibility, |
| /* NotEligibleToImport = */ true, |
| /* Live = */ true, |
| /* Local */ GV->isDSOLocal(), |
| GV->hasLinkOnceODRLinkage() && GV->hasGlobalUnnamedAddr()); |
| CantBePromoted.insert(GV->getGUID()); |
| // Create the appropriate summary type. |
| if (Function *F = dyn_cast<Function>(GV)) { |
| std::unique_ptr<FunctionSummary> Summary = |
| std::make_unique<FunctionSummary>( |
| GVFlags, /*InstCount=*/0, |
| FunctionSummary::FFlags{ |
| F->hasFnAttribute(Attribute::ReadNone), |
| F->hasFnAttribute(Attribute::ReadOnly), |
| F->hasFnAttribute(Attribute::NoRecurse), |
| F->returnDoesNotAlias(), |
| /* NoInline = */ false, |
| F->hasFnAttribute(Attribute::AlwaysInline), |
| F->hasFnAttribute(Attribute::NoUnwind), |
| /* MayThrow */ true, |
| /* HasUnknownCall */ true}, |
| /*EntryCount=*/0, ArrayRef<ValueInfo>{}, |
| ArrayRef<FunctionSummary::EdgeTy>{}, |
| ArrayRef<GlobalValue::GUID>{}, |
| ArrayRef<FunctionSummary::VFuncId>{}, |
| ArrayRef<FunctionSummary::VFuncId>{}, |
| ArrayRef<FunctionSummary::ConstVCall>{}, |
| ArrayRef<FunctionSummary::ConstVCall>{}, |
| ArrayRef<FunctionSummary::ParamAccess>{}); |
| Index.addGlobalValueSummary(*GV, std::move(Summary)); |
| } else { |
| std::unique_ptr<GlobalVarSummary> Summary = |
| std::make_unique<GlobalVarSummary>( |
| GVFlags, |
| GlobalVarSummary::GVarFlags( |
| false, false, cast<GlobalVariable>(GV)->isConstant(), |
| GlobalObject::VCallVisibilityPublic), |
| ArrayRef<ValueInfo>{}); |
| Index.addGlobalValueSummary(*GV, std::move(Summary)); |
| } |
| }); |
| } |
| |
| bool IsThinLTO = true; |
| if (auto *MD = |
| mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO"))) |
| IsThinLTO = MD->getZExtValue(); |
| |
| // Compute summaries for all functions defined in module, and save in the |
| // index. |
| for (auto &F : M) { |
| if (F.isDeclaration()) |
| continue; |
| |
| DominatorTree DT(const_cast<Function &>(F)); |
| BlockFrequencyInfo *BFI = nullptr; |
| std::unique_ptr<BlockFrequencyInfo> BFIPtr; |
| if (GetBFICallback) |
| BFI = GetBFICallback(F); |
| else if (F.hasProfileData()) { |
| LoopInfo LI{DT}; |
| BranchProbabilityInfo BPI{F, LI}; |
| BFIPtr = std::make_unique<BlockFrequencyInfo>(F, BPI, LI); |
| BFI = BFIPtr.get(); |
| } |
| |
| computeFunctionSummary(Index, M, F, BFI, PSI, DT, |
| !LocalsUsed.empty() || HasLocalInlineAsmSymbol, |
| CantBePromoted, IsThinLTO, GetSSICallback); |
| } |
| |
| // Compute summaries for all variables defined in module, and save in the |
| // index. |
| SmallVector<MDNode *, 2> Types; |
| for (const GlobalVariable &G : M.globals()) { |
| if (G.isDeclaration()) |
| continue; |
| computeVariableSummary(Index, G, CantBePromoted, M, Types); |
| } |
| |
| // Compute summaries for all aliases defined in module, and save in the |
| // index. |
| for (const GlobalAlias &A : M.aliases()) |
| computeAliasSummary(Index, A, CantBePromoted); |
| |
| for (auto *V : LocalsUsed) { |
| auto *Summary = Index.getGlobalValueSummary(*V); |
| assert(Summary && "Missing summary for global value"); |
| Summary->setNotEligibleToImport(); |
| } |
| |
| // The linker doesn't know about these LLVM produced values, so we need |
| // to flag them as live in the index to ensure index-based dead value |
| // analysis treats them as live roots of the analysis. |
| setLiveRoot(Index, "llvm.used"); |
| setLiveRoot(Index, "llvm.compiler.used"); |
| setLiveRoot(Index, "llvm.global_ctors"); |
| setLiveRoot(Index, "llvm.global_dtors"); |
| setLiveRoot(Index, "llvm.global.annotations"); |
| |
| for (auto &GlobalList : Index) { |
| // Ignore entries for references that are undefined in the current module. |
| if (GlobalList.second.SummaryList.empty()) |
| continue; |
| |
| assert(GlobalList.second.SummaryList.size() == 1 && |
| "Expected module's index to have one summary per GUID"); |
| auto &Summary = GlobalList.second.SummaryList[0]; |
| if (!IsThinLTO) { |
| Summary->setNotEligibleToImport(); |
| continue; |
| } |
| |
| bool AllRefsCanBeExternallyReferenced = |
| llvm::all_of(Summary->refs(), [&](const ValueInfo &VI) { |
| return !CantBePromoted.count(VI.getGUID()); |
| }); |
| if (!AllRefsCanBeExternallyReferenced) { |
| Summary->setNotEligibleToImport(); |
| continue; |
| } |
| |
| if (auto *FuncSummary = dyn_cast<FunctionSummary>(Summary.get())) { |
| bool AllCallsCanBeExternallyReferenced = llvm::all_of( |
| FuncSummary->calls(), [&](const FunctionSummary::EdgeTy &Edge) { |
| return !CantBePromoted.count(Edge.first.getGUID()); |
| }); |
| if (!AllCallsCanBeExternallyReferenced) |
| Summary->setNotEligibleToImport(); |
| } |
| } |
| |
| if (!ModuleSummaryDotFile.empty()) { |
| std::error_code EC; |
| raw_fd_ostream OSDot(ModuleSummaryDotFile, EC, sys::fs::OpenFlags::OF_None); |
| if (EC) |
| report_fatal_error(Twine("Failed to open dot file ") + |
| ModuleSummaryDotFile + ": " + EC.message() + "\n"); |
| Index.exportToDot(OSDot, {}); |
| } |
| |
| return Index; |
| } |
| |
| AnalysisKey ModuleSummaryIndexAnalysis::Key; |
| |
| ModuleSummaryIndex |
| ModuleSummaryIndexAnalysis::run(Module &M, ModuleAnalysisManager &AM) { |
| ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M); |
| auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager(); |
| bool NeedSSI = needsParamAccessSummary(M); |
| return buildModuleSummaryIndex( |
| M, |
| [&FAM](const Function &F) { |
| return &FAM.getResult<BlockFrequencyAnalysis>( |
| *const_cast<Function *>(&F)); |
| }, |
| &PSI, |
| [&FAM, NeedSSI](const Function &F) -> const StackSafetyInfo * { |
| return NeedSSI ? &FAM.getResult<StackSafetyAnalysis>( |
| const_cast<Function &>(F)) |
| : nullptr; |
| }); |
| } |
| |
| char ModuleSummaryIndexWrapperPass::ID = 0; |
| |
| INITIALIZE_PASS_BEGIN(ModuleSummaryIndexWrapperPass, "module-summary-analysis", |
| "Module Summary Analysis", false, true) |
| INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass) |
| INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass) |
| INITIALIZE_PASS_DEPENDENCY(StackSafetyInfoWrapperPass) |
| INITIALIZE_PASS_END(ModuleSummaryIndexWrapperPass, "module-summary-analysis", |
| "Module Summary Analysis", false, true) |
| |
| ModulePass *llvm::createModuleSummaryIndexWrapperPass() { |
| return new ModuleSummaryIndexWrapperPass(); |
| } |
| |
| ModuleSummaryIndexWrapperPass::ModuleSummaryIndexWrapperPass() |
| : ModulePass(ID) { |
| initializeModuleSummaryIndexWrapperPassPass(*PassRegistry::getPassRegistry()); |
| } |
| |
| bool ModuleSummaryIndexWrapperPass::runOnModule(Module &M) { |
| auto *PSI = &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI(); |
| bool NeedSSI = needsParamAccessSummary(M); |
| Index.emplace(buildModuleSummaryIndex( |
| M, |
| [this](const Function &F) { |
| return &(this->getAnalysis<BlockFrequencyInfoWrapperPass>( |
| *const_cast<Function *>(&F)) |
| .getBFI()); |
| }, |
| PSI, |
| [&](const Function &F) -> const StackSafetyInfo * { |
| return NeedSSI ? &getAnalysis<StackSafetyInfoWrapperPass>( |
| const_cast<Function &>(F)) |
| .getResult() |
| : nullptr; |
| })); |
| return false; |
| } |
| |
| bool ModuleSummaryIndexWrapperPass::doFinalization(Module &M) { |
| Index.reset(); |
| return false; |
| } |
| |
| void ModuleSummaryIndexWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const { |
| AU.setPreservesAll(); |
| AU.addRequired<BlockFrequencyInfoWrapperPass>(); |
| AU.addRequired<ProfileSummaryInfoWrapperPass>(); |
| AU.addRequired<StackSafetyInfoWrapperPass>(); |
| } |
| |
| char ImmutableModuleSummaryIndexWrapperPass::ID = 0; |
| |
| ImmutableModuleSummaryIndexWrapperPass::ImmutableModuleSummaryIndexWrapperPass( |
| const ModuleSummaryIndex *Index) |
| : ImmutablePass(ID), Index(Index) { |
| initializeImmutableModuleSummaryIndexWrapperPassPass( |
| *PassRegistry::getPassRegistry()); |
| } |
| |
| void ImmutableModuleSummaryIndexWrapperPass::getAnalysisUsage( |
| AnalysisUsage &AU) const { |
| AU.setPreservesAll(); |
| } |
| |
| ImmutablePass *llvm::createImmutableModuleSummaryIndexWrapperPass( |
| const ModuleSummaryIndex *Index) { |
| return new ImmutableModuleSummaryIndexWrapperPass(Index); |
| } |
| |
| INITIALIZE_PASS(ImmutableModuleSummaryIndexWrapperPass, "module-summary-info", |
| "Module summary info", false, true) |
