//===- bolt/Core/BinaryFunction.cpp - Low-level function ------------------===// // // 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 BinaryFunction class. // //===----------------------------------------------------------------------===// #include "bolt/Core/BinaryFunction.h" #include "bolt/Core/BinaryBasicBlock.h" #include "bolt/Core/DynoStats.h" #include "bolt/Core/HashUtilities.h" #include "bolt/Core/MCPlusBuilder.h" #include "bolt/Utils/NameResolver.h" #include "bolt/Utils/NameShortener.h" #include "bolt/Utils/Utils.h" #include "llvm/ADT/STLExtras.h" #include "llvm/ADT/SmallSet.h" #include "llvm/ADT/StringExtras.h" #include "llvm/ADT/StringRef.h" #include "llvm/Demangle/Demangle.h" #include "llvm/MC/MCAsmInfo.h" #include "llvm/MC/MCContext.h" #include "llvm/MC/MCDisassembler/MCDisassembler.h" #include "llvm/MC/MCExpr.h" #include "llvm/MC/MCInst.h" #include "llvm/MC/MCInstPrinter.h" #include "llvm/MC/MCRegisterInfo.h" #include "llvm/MC/MCSymbol.h" #include "llvm/Object/ObjectFile.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/GenericDomTreeConstruction.h" #include "llvm/Support/GenericLoopInfoImpl.h" #include "llvm/Support/GraphWriter.h" #include "llvm/Support/LEB128.h" #include "llvm/Support/Regex.h" #include "llvm/Support/Timer.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Support/xxhash.h" #include #include #include #include #include #define DEBUG_TYPE "bolt" using namespace llvm; using namespace bolt; namespace opts { extern cl::OptionCategory BoltCategory; extern cl::OptionCategory BoltOptCategory; extern cl::opt EnableBAT; extern cl::opt Instrument; extern cl::opt StrictMode; extern cl::opt UpdateDebugSections; extern cl::opt Verbosity; extern bool processAllFunctions(); cl::opt CheckEncoding( "check-encoding", cl::desc("perform verification of LLVM instruction encoding/decoding. " "Every instruction in the input is decoded and re-encoded. " "If the resulting bytes do not match the input, a warning message " "is printed."), cl::Hidden, cl::cat(BoltCategory)); static cl::opt DotToolTipCode( "dot-tooltip-code", cl::desc("add basic block instructions as tool tips on nodes"), cl::Hidden, cl::cat(BoltCategory)); cl::opt JumpTables("jump-tables", cl::desc("jump tables support (default=basic)"), cl::init(JTS_BASIC), cl::values( clEnumValN(JTS_NONE, "none", "do not optimize functions with jump tables"), clEnumValN(JTS_BASIC, "basic", "optimize functions with jump tables"), clEnumValN(JTS_MOVE, "move", "move jump tables to a separate section"), clEnumValN(JTS_SPLIT, "split", "split jump tables section into hot and cold based on " "function execution frequency"), clEnumValN(JTS_AGGRESSIVE, "aggressive", "aggressively split jump tables section based on usage " "of the tables")), cl::ZeroOrMore, cl::cat(BoltOptCategory)); static cl::opt NoScan( "no-scan", cl::desc( "do not scan cold functions for external references (may result in " "slower binary)"), cl::Hidden, cl::cat(BoltOptCategory)); cl::opt PreserveBlocksAlignment("preserve-blocks-alignment", cl::desc("try to preserve basic block alignment"), cl::cat(BoltOptCategory)); static cl::opt PrintOutputAddressRange( "print-output-address-range", cl::desc( "print output address range for each basic block in the function when" "BinaryFunction::print is called"), cl::Hidden, cl::cat(BoltOptCategory)); cl::opt PrintDynoStats("dyno-stats", cl::desc("print execution info based on profile"), cl::cat(BoltCategory)); static cl::opt PrintDynoStatsOnly("print-dyno-stats-only", cl::desc("while printing functions output dyno-stats and skip instructions"), cl::init(false), cl::Hidden, cl::cat(BoltCategory)); static cl::list PrintOnly("print-only", cl::CommaSeparated, cl::desc("list of functions to print"), cl::value_desc("func1,func2,func3,..."), cl::Hidden, cl::cat(BoltCategory)); cl::opt TimeBuild("time-build", cl::desc("print time spent constructing binary functions"), cl::Hidden, cl::cat(BoltCategory)); cl::opt TrapOnAVX512("trap-avx512", cl::desc("in relocation mode trap upon entry to any function that uses " "AVX-512 instructions"), cl::init(false), cl::ZeroOrMore, cl::Hidden, cl::cat(BoltCategory)); bool shouldPrint(const BinaryFunction &Function) { if (Function.isIgnored()) return false; if (PrintOnly.empty()) return true; for (std::string &Name : opts::PrintOnly) { if (Function.hasNameRegex(Name)) { return true; } } std::optional Origin = Function.getOriginSectionName(); if (Origin && llvm::any_of(opts::PrintOnly, [&](const std::string &Name) { return Name == *Origin; })) return true; return false; } } // namespace opts namespace llvm { namespace bolt { template static bool emptyRange(const R &Range) { return Range.begin() == Range.end(); } /// Gets debug line information for the instruction located at the given /// address in the original binary. The SMLoc's pointer is used /// to point to this information, which is represented by a /// DebugLineTableRowRef. The returned pointer is null if no debug line /// information for this instruction was found. static SMLoc findDebugLineInformationForInstructionAt( uint64_t Address, DWARFUnit *Unit, const DWARFDebugLine::LineTable *LineTable) { // We use the pointer in SMLoc to store an instance of DebugLineTableRowRef, // which occupies 64 bits. Thus, we can only proceed if the struct fits into // the pointer itself. static_assert( sizeof(decltype(SMLoc().getPointer())) >= sizeof(DebugLineTableRowRef), "Cannot fit instruction debug line information into SMLoc's pointer"); SMLoc NullResult = DebugLineTableRowRef::NULL_ROW.toSMLoc(); uint32_t RowIndex = LineTable->lookupAddress( {Address, object::SectionedAddress::UndefSection}); if (RowIndex == LineTable->UnknownRowIndex) return NullResult; assert(RowIndex < LineTable->Rows.size() && "Line Table lookup returned invalid index."); decltype(SMLoc().getPointer()) Ptr; DebugLineTableRowRef *InstructionLocation = reinterpret_cast(&Ptr); InstructionLocation->DwCompileUnitIndex = Unit->getOffset(); InstructionLocation->RowIndex = RowIndex + 1; return SMLoc::getFromPointer(Ptr); } static std::string buildSectionName(StringRef Prefix, StringRef Name, const BinaryContext &BC) { if (BC.isELF()) return (Prefix + Name).str(); static NameShortener NS; return (Prefix + Twine(NS.getID(Name))).str(); } static raw_ostream &operator<<(raw_ostream &OS, const BinaryFunction::State State) { switch (State) { case BinaryFunction::State::Empty: OS << "empty"; break; case BinaryFunction::State::Disassembled: OS << "disassembled"; break; case BinaryFunction::State::CFG: OS << "CFG constructed"; break; case BinaryFunction::State::CFG_Finalized: OS << "CFG finalized"; break; case BinaryFunction::State::EmittedCFG: OS << "emitted with CFG"; break; case BinaryFunction::State::Emitted: OS << "emitted"; break; } return OS; } std::string BinaryFunction::buildCodeSectionName(StringRef Name, const BinaryContext &BC) { return buildSectionName(BC.isELF() ? ".local.text." : ".l.text.", Name, BC); } std::string BinaryFunction::buildColdCodeSectionName(StringRef Name, const BinaryContext &BC) { return buildSectionName(BC.isELF() ? ".local.cold.text." : ".l.c.text.", Name, BC); } uint64_t BinaryFunction::Count = 0; std::optional BinaryFunction::hasNameRegex(const StringRef Name) const { const std::string RegexName = (Twine("^") + StringRef(Name) + "$").str(); Regex MatchName(RegexName); return forEachName( [&MatchName](StringRef Name) { return MatchName.match(Name); }); } std::optional BinaryFunction::hasRestoredNameRegex(const StringRef Name) const { const std::string RegexName = (Twine("^") + StringRef(Name) + "$").str(); Regex MatchName(RegexName); return forEachName([&MatchName](StringRef Name) { return MatchName.match(NameResolver::restore(Name)); }); } std::string BinaryFunction::getDemangledName() const { StringRef MangledName = NameResolver::restore(getOneName()); return demangle(MangledName.str()); } BinaryBasicBlock * BinaryFunction::getBasicBlockContainingOffset(uint64_t Offset) { if (Offset > Size) return nullptr; if (BasicBlockOffsets.empty()) return nullptr; /* * This is commented out because it makes BOLT too slow. * assert(std::is_sorted(BasicBlockOffsets.begin(), * BasicBlockOffsets.end(), * CompareBasicBlockOffsets()))); */ auto I = llvm::upper_bound(BasicBlockOffsets, BasicBlockOffset(Offset, nullptr), CompareBasicBlockOffsets()); assert(I != BasicBlockOffsets.begin() && "first basic block not at offset 0"); --I; BinaryBasicBlock *BB = I->second; return (Offset < BB->getOffset() + BB->getOriginalSize()) ? BB : nullptr; } void BinaryFunction::markUnreachableBlocks() { std::stack Stack; for (BinaryBasicBlock &BB : blocks()) BB.markValid(false); // Add all entries and landing pads as roots. for (BinaryBasicBlock *BB : BasicBlocks) { if (isEntryPoint(*BB) || BB->isLandingPad()) { Stack.push(BB); BB->markValid(true); continue; } // FIXME: // Also mark BBs with indirect jumps as reachable, since we do not // support removing unused jump tables yet (GH-issue20). for (const MCInst &Inst : *BB) { if (BC.MIB->getJumpTable(Inst)) { Stack.push(BB); BB->markValid(true); break; } } } // Determine reachable BBs from the entry point while (!Stack.empty()) { BinaryBasicBlock *BB = Stack.top(); Stack.pop(); for (BinaryBasicBlock *Succ : BB->successors()) { if (Succ->isValid()) continue; Succ->markValid(true); Stack.push(Succ); } } } // Any unnecessary fallthrough jumps revealed after calling eraseInvalidBBs // will be cleaned up by fixBranches(). std::pair BinaryFunction::eraseInvalidBBs(const MCCodeEmitter *Emitter) { DenseSet InvalidBBs; unsigned Count = 0; uint64_t Bytes = 0; for (BinaryBasicBlock *const BB : BasicBlocks) { if (!BB->isValid()) { assert(!isEntryPoint(*BB) && "all entry blocks must be valid"); InvalidBBs.insert(BB); ++Count; Bytes += BC.computeCodeSize(BB->begin(), BB->end(), Emitter); } } Layout.eraseBasicBlocks(InvalidBBs); BasicBlockListType NewBasicBlocks; for (auto I = BasicBlocks.begin(), E = BasicBlocks.end(); I != E; ++I) { BinaryBasicBlock *BB = *I; if (InvalidBBs.contains(BB)) { // Make sure the block is removed from the list of predecessors. BB->removeAllSuccessors(); DeletedBasicBlocks.push_back(BB); } else { NewBasicBlocks.push_back(BB); } } BasicBlocks = std::move(NewBasicBlocks); assert(BasicBlocks.size() == Layout.block_size()); // Update CFG state if needed if (Count > 0) recomputeLandingPads(); return std::make_pair(Count, Bytes); } bool BinaryFunction::isForwardCall(const MCSymbol *CalleeSymbol) const { // This function should work properly before and after function reordering. // In order to accomplish this, we use the function index (if it is valid). // If the function indices are not valid, we fall back to the original // addresses. This should be ok because the functions without valid indices // should have been ordered with a stable sort. const BinaryFunction *CalleeBF = BC.getFunctionForSymbol(CalleeSymbol); if (CalleeBF) { if (CalleeBF->isInjected()) return true; return compareBinaryFunctionByIndex(this, CalleeBF); } else { // Absolute symbol. ErrorOr CalleeAddressOrError = BC.getSymbolValue(*CalleeSymbol); assert(CalleeAddressOrError && "unregistered symbol found"); return *CalleeAddressOrError > getAddress(); } } void BinaryFunction::dump() const { // getDynoStats calls FunctionLayout::updateLayoutIndices and // BasicBlock::analyzeBranch. The former cannot be const, but should be // removed, the latter should be made const, but seems to require refactoring. // Forcing all callers to have a non-const reference to BinaryFunction to call // dump non-const however is not ideal either. Adding this const_cast is right // now the best solution. It is safe, because BinaryFunction itself is not // modified. Only BinaryBasicBlocks are actually modified (if it all) and we // have mutable pointers to those regardless whether this function is // const-qualified or not. const_cast(*this).print(dbgs(), ""); } void BinaryFunction::print(raw_ostream &OS, std::string Annotation) { if (!opts::shouldPrint(*this)) return; StringRef SectionName = OriginSection ? OriginSection->getName() : ""; OS << "Binary Function \"" << *this << "\" " << Annotation << " {"; std::vector AllNames = getNames(); if (AllNames.size() > 1) { OS << "\n All names : "; const char *Sep = ""; for (const StringRef &Name : AllNames) { OS << Sep << Name; Sep = "\n "; } } OS << "\n Number : " << FunctionNumber; OS << "\n State : " << CurrentState; OS << "\n Address : 0x" << Twine::utohexstr(Address); OS << "\n Size : 0x" << Twine::utohexstr(Size); OS << "\n MaxSize : 0x" << Twine::utohexstr(MaxSize); OS << "\n Offset : 0x" << Twine::utohexstr(getFileOffset()); OS << "\n Section : " << SectionName; OS << "\n Orc Section : " << getCodeSectionName(); OS << "\n LSDA : 0x" << Twine::utohexstr(getLSDAAddress()); OS << "\n IsSimple : " << IsSimple; OS << "\n IsMultiEntry: " << isMultiEntry(); OS << "\n IsSplit : " << isSplit(); OS << "\n BB Count : " << size(); if (HasUnknownControlFlow) OS << "\n Unknown CF : true"; if (getPersonalityFunction()) OS << "\n Personality : " << getPersonalityFunction()->getName(); if (IsFragment) OS << "\n IsFragment : true"; if (isFolded()) OS << "\n FoldedInto : " << *getFoldedIntoFunction(); for (BinaryFunction *ParentFragment : ParentFragments) OS << "\n Parent : " << *ParentFragment; if (!Fragments.empty()) { OS << "\n Fragments : "; ListSeparator LS; for (BinaryFunction *Frag : Fragments) OS << LS << *Frag; } if (hasCFG()) OS << "\n Hash : " << Twine::utohexstr(computeHash()); if (isMultiEntry()) { OS << "\n Secondary Entry Points : "; ListSeparator LS; for (const auto &KV : SecondaryEntryPoints) OS << LS << KV.second->getName(); } if (FrameInstructions.size()) OS << "\n CFI Instrs : " << FrameInstructions.size(); if (!Layout.block_empty()) { OS << "\n BB Layout : "; ListSeparator LS; for (const BinaryBasicBlock *BB : Layout.blocks()) OS << LS << BB->getName(); } if (getImageAddress()) OS << "\n Image : 0x" << Twine::utohexstr(getImageAddress()); if (ExecutionCount != COUNT_NO_PROFILE) { OS << "\n Exec Count : " << ExecutionCount; OS << "\n Branch Count: " << RawBranchCount; OS << "\n Profile Acc : " << format("%.1f%%", ProfileMatchRatio * 100.0f); } if (opts::PrintDynoStats && !getLayout().block_empty()) { OS << '\n'; DynoStats dynoStats = getDynoStats(*this); OS << dynoStats; } OS << "\n}\n"; if (opts::PrintDynoStatsOnly || !BC.InstPrinter) return; // Offset of the instruction in function. uint64_t Offset = 0; if (BasicBlocks.empty() && !Instructions.empty()) { // Print before CFG was built. for (const std::pair &II : Instructions) { Offset = II.first; // Print label if exists at this offset. auto LI = Labels.find(Offset); if (LI != Labels.end()) { if (const MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(LI->second)) OS << EntrySymbol->getName() << " (Entry Point):\n"; OS << LI->second->getName() << ":\n"; } BC.printInstruction(OS, II.second, Offset, this); } } StringRef SplitPointMsg = ""; for (const FunctionFragment &FF : Layout.fragments()) { OS << SplitPointMsg; SplitPointMsg = "------- HOT-COLD SPLIT POINT -------\n\n"; for (const BinaryBasicBlock *BB : FF) { OS << BB->getName() << " (" << BB->size() << " instructions, align : " << BB->getAlignment() << ")\n"; if (opts::PrintOutputAddressRange) OS << formatv(" Output Address Range: [{0:x}, {1:x}) ({2} bytes)\n", BB->getOutputAddressRange().first, BB->getOutputAddressRange().second, BB->getOutputSize()); if (isEntryPoint(*BB)) { if (MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(*BB)) OS << " Secondary Entry Point: " << EntrySymbol->getName() << '\n'; else OS << " Entry Point\n"; } if (BB->isLandingPad()) OS << " Landing Pad\n"; uint64_t BBExecCount = BB->getExecutionCount(); if (hasValidProfile()) { OS << " Exec Count : "; if (BB->getExecutionCount() != BinaryBasicBlock::COUNT_NO_PROFILE) OS << BBExecCount << '\n'; else OS << "\n"; } if (hasCFI()) OS << " CFI State : " << BB->getCFIState() << '\n'; if (opts::EnableBAT) { OS << " Input offset: 0x" << Twine::utohexstr(BB->getInputOffset()) << "\n"; } if (!BB->pred_empty()) { OS << " Predecessors: "; ListSeparator LS; for (BinaryBasicBlock *Pred : BB->predecessors()) OS << LS << Pred->getName(); OS << '\n'; } if (!BB->throw_empty()) { OS << " Throwers: "; ListSeparator LS; for (BinaryBasicBlock *Throw : BB->throwers()) OS << LS << Throw->getName(); OS << '\n'; } Offset = alignTo(Offset, BB->getAlignment()); // Note: offsets are imprecise since this is happening prior to // relaxation. Offset = BC.printInstructions(OS, BB->begin(), BB->end(), Offset, this); if (!BB->succ_empty()) { OS << " Successors: "; // For more than 2 successors, sort them based on frequency. std::vector Indices(BB->succ_size()); std::iota(Indices.begin(), Indices.end(), 0); if (BB->succ_size() > 2 && BB->getKnownExecutionCount()) { llvm::stable_sort(Indices, [&](const uint64_t A, const uint64_t B) { return BB->BranchInfo[B] < BB->BranchInfo[A]; }); } ListSeparator LS; for (unsigned I = 0; I < Indices.size(); ++I) { BinaryBasicBlock *Succ = BB->Successors[Indices[I]]; const BinaryBasicBlock::BinaryBranchInfo &BI = BB->BranchInfo[Indices[I]]; OS << LS << Succ->getName(); if (ExecutionCount != COUNT_NO_PROFILE && BI.MispredictedCount != BinaryBasicBlock::COUNT_INFERRED) { OS << " (mispreds: " << BI.MispredictedCount << ", count: " << BI.Count << ")"; } else if (ExecutionCount != COUNT_NO_PROFILE && BI.Count != BinaryBasicBlock::COUNT_NO_PROFILE) { OS << " (inferred count: " << BI.Count << ")"; } } OS << '\n'; } if (!BB->lp_empty()) { OS << " Landing Pads: "; ListSeparator LS; for (BinaryBasicBlock *LP : BB->landing_pads()) { OS << LS << LP->getName(); if (ExecutionCount != COUNT_NO_PROFILE) { OS << " (count: " << LP->getExecutionCount() << ")"; } } OS << '\n'; } // In CFG_Finalized state we can miscalculate CFI state at exit. if (CurrentState == State::CFG && hasCFI()) { const int32_t CFIStateAtExit = BB->getCFIStateAtExit(); if (CFIStateAtExit >= 0) OS << " CFI State: " << CFIStateAtExit << '\n'; } OS << '\n'; } } // Dump new exception ranges for the function. if (!CallSites.empty()) { OS << "EH table:\n"; for (const FunctionFragment &FF : getLayout().fragments()) { for (const auto &FCSI : getCallSites(FF.getFragmentNum())) { const CallSite &CSI = FCSI.second; OS << " [" << *CSI.Start << ", " << *CSI.End << ") landing pad : "; if (CSI.LP) OS << *CSI.LP; else OS << "0"; OS << ", action : " << CSI.Action << '\n'; } } OS << '\n'; } // Print all jump tables. for (const std::pair &JTI : JumpTables) JTI.second->print(OS); OS << "DWARF CFI Instructions:\n"; if (OffsetToCFI.size()) { // Pre-buildCFG information for (const std::pair &Elmt : OffsetToCFI) { OS << format(" %08x:\t", Elmt.first); assert(Elmt.second < FrameInstructions.size() && "Incorrect CFI offset"); BinaryContext::printCFI(OS, FrameInstructions[Elmt.second]); OS << "\n"; } } else { // Post-buildCFG information for (uint32_t I = 0, E = FrameInstructions.size(); I != E; ++I) { const MCCFIInstruction &CFI = FrameInstructions[I]; OS << format(" %d:\t", I); BinaryContext::printCFI(OS, CFI); OS << "\n"; } } if (FrameInstructions.empty()) OS << " \n"; OS << "End of Function \"" << *this << "\"\n\n"; } void BinaryFunction::printRelocations(raw_ostream &OS, uint64_t Offset, uint64_t Size) const { const char *Sep = " # Relocs: "; auto RI = Relocations.lower_bound(Offset); while (RI != Relocations.end() && RI->first < Offset + Size) { OS << Sep << "(R: " << RI->second << ")"; Sep = ", "; ++RI; } } static std::string mutateDWARFExpressionTargetReg(const MCCFIInstruction &Instr, MCPhysReg NewReg) { StringRef ExprBytes = Instr.getValues(); assert(ExprBytes.size() > 1 && "DWARF expression CFI is too short"); uint8_t Opcode = ExprBytes[0]; assert((Opcode == dwarf::DW_CFA_expression || Opcode == dwarf::DW_CFA_val_expression) && "invalid DWARF expression CFI"); (void)Opcode; const uint8_t *const Start = reinterpret_cast(ExprBytes.drop_front(1).data()); const uint8_t *const End = reinterpret_cast(Start + ExprBytes.size() - 1); unsigned Size = 0; decodeULEB128(Start, &Size, End); assert(Size > 0 && "Invalid reg encoding for DWARF expression CFI"); SmallString<8> Tmp; raw_svector_ostream OSE(Tmp); encodeULEB128(NewReg, OSE); return Twine(ExprBytes.slice(0, 1)) .concat(OSE.str()) .concat(ExprBytes.drop_front(1 + Size)) .str(); } void BinaryFunction::mutateCFIRegisterFor(const MCInst &Instr, MCPhysReg NewReg) { const MCCFIInstruction *OldCFI = getCFIFor(Instr); assert(OldCFI && "invalid CFI instr"); switch (OldCFI->getOperation()) { default: llvm_unreachable("Unexpected instruction"); case MCCFIInstruction::OpDefCfa: setCFIFor(Instr, MCCFIInstruction::cfiDefCfa(nullptr, NewReg, OldCFI->getOffset())); break; case MCCFIInstruction::OpDefCfaRegister: setCFIFor(Instr, MCCFIInstruction::createDefCfaRegister(nullptr, NewReg)); break; case MCCFIInstruction::OpOffset: setCFIFor(Instr, MCCFIInstruction::createOffset(nullptr, NewReg, OldCFI->getOffset())); break; case MCCFIInstruction::OpRegister: setCFIFor(Instr, MCCFIInstruction::createRegister(nullptr, NewReg, OldCFI->getRegister2())); break; case MCCFIInstruction::OpSameValue: setCFIFor(Instr, MCCFIInstruction::createSameValue(nullptr, NewReg)); break; case MCCFIInstruction::OpEscape: setCFIFor(Instr, MCCFIInstruction::createEscape( nullptr, StringRef(mutateDWARFExpressionTargetReg(*OldCFI, NewReg)))); break; case MCCFIInstruction::OpRestore: setCFIFor(Instr, MCCFIInstruction::createRestore(nullptr, NewReg)); break; case MCCFIInstruction::OpUndefined: setCFIFor(Instr, MCCFIInstruction::createUndefined(nullptr, NewReg)); break; } } const MCCFIInstruction *BinaryFunction::mutateCFIOffsetFor(const MCInst &Instr, int64_t NewOffset) { const MCCFIInstruction *OldCFI = getCFIFor(Instr); assert(OldCFI && "invalid CFI instr"); switch (OldCFI->getOperation()) { default: llvm_unreachable("Unexpected instruction"); case MCCFIInstruction::OpDefCfaOffset: setCFIFor(Instr, MCCFIInstruction::cfiDefCfaOffset(nullptr, NewOffset)); break; case MCCFIInstruction::OpAdjustCfaOffset: setCFIFor(Instr, MCCFIInstruction::createAdjustCfaOffset(nullptr, NewOffset)); break; case MCCFIInstruction::OpDefCfa: setCFIFor(Instr, MCCFIInstruction::cfiDefCfa(nullptr, OldCFI->getRegister(), NewOffset)); break; case MCCFIInstruction::OpOffset: setCFIFor(Instr, MCCFIInstruction::createOffset( nullptr, OldCFI->getRegister(), NewOffset)); break; } return getCFIFor(Instr); } IndirectBranchType BinaryFunction::processIndirectBranch(MCInst &Instruction, unsigned Size, uint64_t Offset, uint64_t &TargetAddress) { const unsigned PtrSize = BC.AsmInfo->getCodePointerSize(); // The instruction referencing memory used by the branch instruction. // It could be the branch instruction itself or one of the instructions // setting the value of the register used by the branch. MCInst *MemLocInstr; // The instruction loading the fixed PIC jump table entry value. MCInst *FixedEntryLoadInstr; // Address of the table referenced by MemLocInstr. Could be either an // array of function pointers, or a jump table. uint64_t ArrayStart = 0; unsigned BaseRegNum, IndexRegNum; int64_t DispValue; const MCExpr *DispExpr; // In AArch, identify the instruction adding the PC-relative offset to // jump table entries to correctly decode it. MCInst *PCRelBaseInstr; uint64_t PCRelAddr = 0; auto Begin = Instructions.begin(); if (BC.isAArch64()) { // Start at the last label as an approximation of the current basic block. // This is a heuristic, since the full set of labels have yet to be // determined for (const uint32_t Offset : llvm::make_first_range(llvm::reverse(Labels))) { auto II = Instructions.find(Offset); if (II != Instructions.end()) { Begin = II; break; } } } IndirectBranchType BranchType = BC.MIB->analyzeIndirectBranch( Instruction, Begin, Instructions.end(), PtrSize, MemLocInstr, BaseRegNum, IndexRegNum, DispValue, DispExpr, PCRelBaseInstr, FixedEntryLoadInstr); if (BranchType == IndirectBranchType::UNKNOWN && !MemLocInstr) return BranchType; if (MemLocInstr != &Instruction) IndexRegNum = BC.MIB->getNoRegister(); if (BC.isAArch64()) { const MCSymbol *Sym = BC.MIB->getTargetSymbol(*PCRelBaseInstr, 1); assert(Sym && "Symbol extraction failed"); ErrorOr SymValueOrError = BC.getSymbolValue(*Sym); if (SymValueOrError) { PCRelAddr = *SymValueOrError; } else { for (std::pair &Elmt : Labels) { if (Elmt.second == Sym) { PCRelAddr = Elmt.first + getAddress(); break; } } } uint64_t InstrAddr = 0; for (auto II = Instructions.rbegin(); II != Instructions.rend(); ++II) { if (&II->second == PCRelBaseInstr) { InstrAddr = II->first + getAddress(); break; } } assert(InstrAddr != 0 && "instruction not found"); // We do this to avoid spurious references to code locations outside this // function (for example, if the indirect jump lives in the last basic // block of the function, it will create a reference to the next function). // This replaces a symbol reference with an immediate. BC.MIB->replaceMemOperandDisp(*PCRelBaseInstr, MCOperand::createImm(PCRelAddr - InstrAddr)); // FIXME: Disable full jump table processing for AArch64 until we have a // proper way of determining the jump table limits. return IndirectBranchType::UNKNOWN; } auto getExprValue = [&](const MCExpr *Expr) { const MCSymbol *TargetSym; uint64_t TargetOffset; std::tie(TargetSym, TargetOffset) = BC.MIB->getTargetSymbolInfo(Expr); ErrorOr SymValueOrError = BC.getSymbolValue(*TargetSym); assert(SymValueOrError && "Global symbol needs a value"); return *SymValueOrError + TargetOffset; }; // RIP-relative addressing should be converted to symbol form by now // in processed instructions (but not in jump). if (DispExpr) { ArrayStart = getExprValue(DispExpr); BaseRegNum = BC.MIB->getNoRegister(); if (BC.isAArch64()) { ArrayStart &= ~0xFFFULL; ArrayStart += DispValue & 0xFFFULL; } } else { ArrayStart = static_cast(DispValue); } if (BaseRegNum == BC.MRI->getProgramCounter()) ArrayStart += getAddress() + Offset + Size; if (FixedEntryLoadInstr) { assert(BranchType == IndirectBranchType::POSSIBLE_PIC_FIXED_BRANCH && "Invalid IndirectBranch type"); MCInst::iterator FixedEntryDispOperand = BC.MIB->getMemOperandDisp(*FixedEntryLoadInstr); assert(FixedEntryDispOperand != FixedEntryLoadInstr->end() && "Invalid memory instruction"); const MCExpr *FixedEntryDispExpr = FixedEntryDispOperand->getExpr(); const uint64_t EntryAddress = getExprValue(FixedEntryDispExpr); uint64_t EntrySize = BC.getJumpTableEntrySize(JumpTable::JTT_PIC); ErrorOr Value = BC.getSignedValueAtAddress(EntryAddress, EntrySize); if (!Value) return IndirectBranchType::UNKNOWN; BC.outs() << "BOLT-INFO: fixed PIC indirect branch detected in " << *this << " at 0x" << Twine::utohexstr(getAddress() + Offset) << " referencing data at 0x" << Twine::utohexstr(EntryAddress) << " the destination value is 0x" << Twine::utohexstr(ArrayStart + *Value) << '\n'; TargetAddress = ArrayStart + *Value; // Remove spurious JumpTable at EntryAddress caused by PIC reference from // the load instruction. BC.deleteJumpTable(EntryAddress); // Replace FixedEntryDispExpr used in target address calculation with outer // jump table reference. JumpTable *JT = BC.getJumpTableContainingAddress(ArrayStart); assert(JT && "Must have a containing jump table for PIC fixed branch"); BC.MIB->replaceMemOperandDisp(*FixedEntryLoadInstr, JT->getFirstLabel(), EntryAddress - ArrayStart, &*BC.Ctx); return BranchType; } LLVM_DEBUG(dbgs() << "BOLT-DEBUG: addressed memory is 0x" << Twine::utohexstr(ArrayStart) << '\n'); ErrorOr Section = BC.getSectionForAddress(ArrayStart); if (!Section) { // No section - possibly an absolute address. Since we don't allow // internal function addresses to escape the function scope - we // consider it a tail call. if (opts::Verbosity >= 1) { BC.errs() << "BOLT-WARNING: no section for address 0x" << Twine::utohexstr(ArrayStart) << " referenced from function " << *this << '\n'; } return IndirectBranchType::POSSIBLE_TAIL_CALL; } if (Section->isVirtual()) { // The contents are filled at runtime. return IndirectBranchType::POSSIBLE_TAIL_CALL; } if (BranchType == IndirectBranchType::POSSIBLE_FIXED_BRANCH) { ErrorOr Value = BC.getPointerAtAddress(ArrayStart); if (!Value) return IndirectBranchType::UNKNOWN; if (BC.getSectionForAddress(ArrayStart)->isWritable()) return IndirectBranchType::UNKNOWN; BC.outs() << "BOLT-INFO: fixed indirect branch detected in " << *this << " at 0x" << Twine::utohexstr(getAddress() + Offset) << " referencing data at 0x" << Twine::utohexstr(ArrayStart) << " the destination value is 0x" << Twine::utohexstr(*Value) << '\n'; TargetAddress = *Value; return BranchType; } // Check if there's already a jump table registered at this address. MemoryContentsType MemType; if (JumpTable *JT = BC.getJumpTableContainingAddress(ArrayStart)) { switch (JT->Type) { case JumpTable::JTT_NORMAL: MemType = MemoryContentsType::POSSIBLE_JUMP_TABLE; break; case JumpTable::JTT_PIC: MemType = MemoryContentsType::POSSIBLE_PIC_JUMP_TABLE; break; } } else { MemType = BC.analyzeMemoryAt(ArrayStart, *this); } // Check that jump table type in instruction pattern matches memory contents. JumpTable::JumpTableType JTType; if (BranchType == IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE) { if (MemType != MemoryContentsType::POSSIBLE_PIC_JUMP_TABLE) return IndirectBranchType::UNKNOWN; JTType = JumpTable::JTT_PIC; } else { if (MemType == MemoryContentsType::POSSIBLE_PIC_JUMP_TABLE) return IndirectBranchType::UNKNOWN; if (MemType == MemoryContentsType::UNKNOWN) return IndirectBranchType::POSSIBLE_TAIL_CALL; BranchType = IndirectBranchType::POSSIBLE_JUMP_TABLE; JTType = JumpTable::JTT_NORMAL; } // Convert the instruction into jump table branch. const MCSymbol *JTLabel = BC.getOrCreateJumpTable(*this, ArrayStart, JTType); BC.MIB->replaceMemOperandDisp(*MemLocInstr, JTLabel, BC.Ctx.get()); BC.MIB->setJumpTable(Instruction, ArrayStart, IndexRegNum); JTSites.emplace_back(Offset, ArrayStart); return BranchType; } MCSymbol *BinaryFunction::getOrCreateLocalLabel(uint64_t Address, bool CreatePastEnd) { const uint64_t Offset = Address - getAddress(); if ((Offset == getSize()) && CreatePastEnd) return getFunctionEndLabel(); auto LI = Labels.find(Offset); if (LI != Labels.end()) return LI->second; // For AArch64, check if this address is part of a constant island. if (BC.isAArch64()) { if (MCSymbol *IslandSym = getOrCreateIslandAccess(Address)) return IslandSym; } MCSymbol *Label = BC.Ctx->createNamedTempSymbol(); Labels[Offset] = Label; return Label; } ErrorOr> BinaryFunction::getData() const { BinarySection &Section = *getOriginSection(); assert(Section.containsRange(getAddress(), getMaxSize()) && "wrong section for function"); if (!Section.isText() || Section.isVirtual() || !Section.getSize()) return std::make_error_code(std::errc::bad_address); StringRef SectionContents = Section.getContents(); assert(SectionContents.size() == Section.getSize() && "section size mismatch"); // Function offset from the section start. uint64_t Offset = getAddress() - Section.getAddress(); auto *Bytes = reinterpret_cast(SectionContents.data()); return ArrayRef(Bytes + Offset, getMaxSize()); } size_t BinaryFunction::getSizeOfDataInCodeAt(uint64_t Offset) const { if (!Islands) return 0; if (!llvm::is_contained(Islands->DataOffsets, Offset)) return 0; auto Iter = Islands->CodeOffsets.upper_bound(Offset); if (Iter != Islands->CodeOffsets.end()) return *Iter - Offset; return getSize() - Offset; } bool BinaryFunction::isZeroPaddingAt(uint64_t Offset) const { ArrayRef FunctionData = *getData(); uint64_t EndOfCode = getSize(); if (Islands) { auto Iter = Islands->DataOffsets.upper_bound(Offset); if (Iter != Islands->DataOffsets.end()) EndOfCode = *Iter; } for (uint64_t I = Offset; I < EndOfCode; ++I) if (FunctionData[I] != 0) return false; return true; } Error BinaryFunction::handlePCRelOperand(MCInst &Instruction, uint64_t Address, uint64_t Size) { auto &MIB = BC.MIB; uint64_t TargetAddress = 0; if (!MIB->evaluateMemOperandTarget(Instruction, TargetAddress, Address, Size)) { std::string Msg; raw_string_ostream SS(Msg); SS << "BOLT-ERROR: PC-relative operand can't be evaluated:\n"; BC.InstPrinter->printInst(&Instruction, 0, "", *BC.STI, SS); SS << '\n'; Instruction.dump_pretty(SS, BC.InstPrinter.get()); SS << '\n'; SS << "BOLT-ERROR: cannot handle PC-relative operand at 0x" << Twine::utohexstr(Address) << ". Skipping function " << *this << ".\n"; if (BC.HasRelocations) return createFatalBOLTError(Msg); IsSimple = false; return createNonFatalBOLTError(Msg); } if (TargetAddress == 0 && opts::Verbosity >= 1) { BC.outs() << "BOLT-INFO: PC-relative operand is zero in function " << *this << '\n'; } const MCSymbol *TargetSymbol; uint64_t TargetOffset; std::tie(TargetSymbol, TargetOffset) = BC.handleAddressRef(TargetAddress, *this, /*IsPCRel*/ true); bool ReplaceSuccess = MIB->replaceMemOperandDisp( Instruction, TargetSymbol, static_cast(TargetOffset), &*BC.Ctx); (void)ReplaceSuccess; assert(ReplaceSuccess && "Failed to replace mem operand with symbol+off."); return Error::success(); } MCSymbol *BinaryFunction::handleExternalReference(MCInst &Instruction, uint64_t Size, uint64_t Offset, uint64_t TargetAddress, bool &IsCall) { auto &MIB = BC.MIB; const uint64_t AbsoluteInstrAddr = getAddress() + Offset; BC.addInterproceduralReference(this, TargetAddress); if (opts::Verbosity >= 2 && !IsCall && Size == 2 && !BC.HasRelocations) { BC.errs() << "BOLT-WARNING: relaxed tail call detected at 0x" << Twine::utohexstr(AbsoluteInstrAddr) << " in function " << *this << ". Code size will be increased.\n"; } assert(!MIB->isTailCall(Instruction) && "synthetic tail call instruction found"); // This is a call regardless of the opcode. // Assign proper opcode for tail calls, so that they could be // treated as calls. if (!IsCall) { if (!MIB->convertJmpToTailCall(Instruction)) { assert(MIB->isConditionalBranch(Instruction) && "unknown tail call instruction"); if (opts::Verbosity >= 2) { BC.errs() << "BOLT-WARNING: conditional tail call detected in " << "function " << *this << " at 0x" << Twine::utohexstr(AbsoluteInstrAddr) << ".\n"; } } IsCall = true; } if (opts::Verbosity >= 2 && TargetAddress == 0) { // We actually see calls to address 0 in presence of weak // symbols originating from libraries. This code is never meant // to be executed. BC.outs() << "BOLT-INFO: Function " << *this << " has a call to address zero.\n"; } return BC.getOrCreateGlobalSymbol(TargetAddress, "FUNCat"); } void BinaryFunction::handleIndirectBranch(MCInst &Instruction, uint64_t Size, uint64_t Offset) { auto &MIB = BC.MIB; uint64_t IndirectTarget = 0; IndirectBranchType Result = processIndirectBranch(Instruction, Size, Offset, IndirectTarget); switch (Result) { default: llvm_unreachable("unexpected result"); case IndirectBranchType::POSSIBLE_TAIL_CALL: { bool Result = MIB->convertJmpToTailCall(Instruction); (void)Result; assert(Result); break; } case IndirectBranchType::POSSIBLE_JUMP_TABLE: case IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE: case IndirectBranchType::POSSIBLE_PIC_FIXED_BRANCH: if (opts::JumpTables == JTS_NONE) IsSimple = false; break; case IndirectBranchType::POSSIBLE_FIXED_BRANCH: { if (containsAddress(IndirectTarget)) { const MCSymbol *TargetSymbol = getOrCreateLocalLabel(IndirectTarget); Instruction.clear(); MIB->createUncondBranch(Instruction, TargetSymbol, BC.Ctx.get()); TakenBranches.emplace_back(Offset, IndirectTarget - getAddress()); addEntryPointAtOffset(IndirectTarget - getAddress()); } else { MIB->convertJmpToTailCall(Instruction); BC.addInterproceduralReference(this, IndirectTarget); } break; } case IndirectBranchType::UNKNOWN: // Keep processing. We'll do more checks and fixes in // postProcessIndirectBranches(). UnknownIndirectBranchOffsets.emplace(Offset); break; } } void BinaryFunction::handleAArch64IndirectCall(MCInst &Instruction, const uint64_t Offset) { auto &MIB = BC.MIB; const uint64_t AbsoluteInstrAddr = getAddress() + Offset; MCInst *TargetHiBits, *TargetLowBits; uint64_t TargetAddress, Count; Count = MIB->matchLinkerVeneer(Instructions.begin(), Instructions.end(), AbsoluteInstrAddr, Instruction, TargetHiBits, TargetLowBits, TargetAddress); if (Count) { MIB->addAnnotation(Instruction, "AArch64Veneer", true); --Count; for (auto It = std::prev(Instructions.end()); Count != 0; It = std::prev(It), --Count) { MIB->addAnnotation(It->second, "AArch64Veneer", true); } BC.addAdrpAddRelocAArch64(*this, *TargetLowBits, *TargetHiBits, TargetAddress); } } std::optional BinaryFunction::disassembleInstructionAtOffset(uint64_t Offset) const { assert(CurrentState == State::Empty && "Function should not be disassembled"); assert(Offset < MaxSize && "Invalid offset"); ErrorOr> FunctionData = getData(); assert(FunctionData && "Cannot get function as data"); MCInst Instr; uint64_t InstrSize = 0; const uint64_t InstrAddress = getAddress() + Offset; if (BC.DisAsm->getInstruction(Instr, InstrSize, FunctionData->slice(Offset), InstrAddress, nulls())) return Instr; return std::nullopt; } Error BinaryFunction::disassemble() { NamedRegionTimer T("disassemble", "Disassemble function", "buildfuncs", "Build Binary Functions", opts::TimeBuild); ErrorOr> ErrorOrFunctionData = getData(); assert(ErrorOrFunctionData && "function data is not available"); ArrayRef FunctionData = *ErrorOrFunctionData; assert(FunctionData.size() == getMaxSize() && "function size does not match raw data size"); auto &Ctx = BC.Ctx; auto &MIB = BC.MIB; BC.SymbolicDisAsm->setSymbolizer(MIB->createTargetSymbolizer(*this)); // Insert a label at the beginning of the function. This will be our first // basic block. Labels[0] = Ctx->createNamedTempSymbol("BB0"); // Map offsets in the function to a label that should always point to the // corresponding instruction. This is used for labels that shouldn't point to // the start of a basic block but always to a specific instruction. This is // used, for example, on RISC-V where %pcrel_lo relocations point to the // corresponding %pcrel_hi. LabelsMapType InstructionLabels; uint64_t Size = 0; // instruction size for (uint64_t Offset = 0; Offset < getSize(); Offset += Size) { MCInst Instruction; const uint64_t AbsoluteInstrAddr = getAddress() + Offset; // Check for data inside code and ignore it if (const size_t DataInCodeSize = getSizeOfDataInCodeAt(Offset)) { Size = DataInCodeSize; continue; } if (!BC.SymbolicDisAsm->getInstruction(Instruction, Size, FunctionData.slice(Offset), AbsoluteInstrAddr, nulls())) { // Functions with "soft" boundaries, e.g. coming from assembly source, // can have 0-byte padding at the end. if (isZeroPaddingAt(Offset)) break; BC.errs() << "BOLT-WARNING: unable to disassemble instruction at offset 0x" << Twine::utohexstr(Offset) << " (address 0x" << Twine::utohexstr(AbsoluteInstrAddr) << ") in function " << *this << '\n'; // Some AVX-512 instructions could not be disassembled at all. if (BC.HasRelocations && opts::TrapOnAVX512 && BC.isX86()) { setTrapOnEntry(); BC.TrappedFunctions.push_back(this); } else { setIgnored(); } break; } // Check integrity of LLVM assembler/disassembler. if (opts::CheckEncoding && !BC.MIB->isBranch(Instruction) && !BC.MIB->isCall(Instruction) && !BC.MIB->isNoop(Instruction)) { if (!BC.validateInstructionEncoding(FunctionData.slice(Offset, Size))) { BC.errs() << "BOLT-WARNING: mismatching LLVM encoding detected in " << "function " << *this << " for instruction :\n"; BC.printInstruction(BC.errs(), Instruction, AbsoluteInstrAddr); BC.errs() << '\n'; } } // Special handling for AVX-512 instructions. if (MIB->hasEVEXEncoding(Instruction)) { if (BC.HasRelocations && opts::TrapOnAVX512) { setTrapOnEntry(); BC.TrappedFunctions.push_back(this); break; } if (!BC.validateInstructionEncoding(FunctionData.slice(Offset, Size))) { BC.errs() << "BOLT-WARNING: internal assembler/disassembler error " "detected for AVX512 instruction:\n"; BC.printInstruction(BC.errs(), Instruction, AbsoluteInstrAddr); BC.errs() << " in function " << *this << '\n'; setIgnored(); break; } } bool IsUnsupported = BC.MIB->isUnsupportedInstruction(Instruction); if (IsUnsupported) setIgnored(); if (MIB->isBranch(Instruction) || MIB->isCall(Instruction)) { uint64_t TargetAddress = 0; if (MIB->evaluateBranch(Instruction, AbsoluteInstrAddr, Size, TargetAddress)) { // Check if the target is within the same function. Otherwise it's // a call, possibly a tail call. // // If the target *is* the function address it could be either a branch // or a recursive call. bool IsCall = MIB->isCall(Instruction); const bool IsCondBranch = MIB->isConditionalBranch(Instruction); MCSymbol *TargetSymbol = nullptr; if (IsUnsupported) if (auto *TargetFunc = BC.getBinaryFunctionContainingAddress(TargetAddress)) TargetFunc->setIgnored(); if (IsCall && TargetAddress == getAddress()) { // A recursive call. Calls to internal blocks are handled by // ValidateInternalCalls pass. TargetSymbol = getSymbol(); } if (!TargetSymbol) { // Create either local label or external symbol. if (containsAddress(TargetAddress)) { TargetSymbol = getOrCreateLocalLabel(TargetAddress); } else { if (TargetAddress == getAddress() + getSize() && TargetAddress < getAddress() + getMaxSize() && !(BC.isAArch64() && BC.handleAArch64Veneer(TargetAddress, /*MatchOnly*/ true))) { // Result of __builtin_unreachable(). LLVM_DEBUG(dbgs() << "BOLT-DEBUG: jump past end detected at 0x" << Twine::utohexstr(AbsoluteInstrAddr) << " in function " << *this << " : replacing with nop.\n"); BC.MIB->createNoop(Instruction); if (IsCondBranch) { // Register branch offset for profile validation. IgnoredBranches.emplace_back(Offset, Offset + Size); } goto add_instruction; } // May update Instruction and IsCall TargetSymbol = handleExternalReference(Instruction, Size, Offset, TargetAddress, IsCall); } } if (!IsCall) { // Add taken branch info. TakenBranches.emplace_back(Offset, TargetAddress - getAddress()); } BC.MIB->replaceBranchTarget(Instruction, TargetSymbol, &*Ctx); // Mark CTC. if (IsCondBranch && IsCall) MIB->setConditionalTailCall(Instruction, TargetAddress); } else { // Could not evaluate branch. Should be an indirect call or an // indirect branch. Bail out on the latter case. if (MIB->isIndirectBranch(Instruction)) handleIndirectBranch(Instruction, Size, Offset); // Indirect call. We only need to fix it if the operand is RIP-relative. if (IsSimple && MIB->hasPCRelOperand(Instruction)) { if (auto NewE = handleErrors( handlePCRelOperand(Instruction, AbsoluteInstrAddr, Size), [&](const BOLTError &E) -> Error { if (E.isFatal()) return Error(std::make_unique(std::move(E))); if (!E.getMessage().empty()) E.log(BC.errs()); return Error::success(); })) { return Error(std::move(NewE)); } } if (BC.isAArch64()) handleAArch64IndirectCall(Instruction, Offset); } } else if (BC.isAArch64() || BC.isRISCV()) { // Check if there's a relocation associated with this instruction. bool UsedReloc = false; for (auto Itr = Relocations.lower_bound(Offset), ItrE = Relocations.lower_bound(Offset + Size); Itr != ItrE; ++Itr) { const Relocation &Relocation = Itr->second; MCSymbol *Symbol = Relocation.Symbol; if (Relocation::isInstructionReference(Relocation.Type)) { uint64_t RefOffset = Relocation.Value - getAddress(); LabelsMapType::iterator LI = InstructionLabels.find(RefOffset); if (LI == InstructionLabels.end()) { Symbol = BC.Ctx->createNamedTempSymbol(); InstructionLabels.emplace(RefOffset, Symbol); } else { Symbol = LI->second; } } int64_t Value = Relocation.Value; const bool Result = BC.MIB->replaceImmWithSymbolRef( Instruction, Symbol, Relocation.Addend, Ctx.get(), Value, Relocation.Type); (void)Result; assert(Result && "cannot replace immediate with relocation"); // For aarch64, if we replaced an immediate with a symbol from a // relocation, we mark it so we do not try to further process a // pc-relative operand. All we need is the symbol. UsedReloc = true; } if (!BC.isRISCV() && MIB->hasPCRelOperand(Instruction) && !UsedReloc) { if (auto NewE = handleErrors( handlePCRelOperand(Instruction, AbsoluteInstrAddr, Size), [&](const BOLTError &E) -> Error { if (E.isFatal()) return Error(std::make_unique(std::move(E))); if (!E.getMessage().empty()) E.log(BC.errs()); return Error::success(); })) return Error(std::move(NewE)); } } add_instruction: if (getDWARFLineTable()) { Instruction.setLoc(findDebugLineInformationForInstructionAt( AbsoluteInstrAddr, getDWARFUnit(), getDWARFLineTable())); } // Record offset of the instruction for profile matching. if (BC.keepOffsetForInstruction(Instruction)) MIB->setOffset(Instruction, static_cast(Offset)); if (BC.isX86() && BC.MIB->isNoop(Instruction)) { // NOTE: disassembly loses the correct size information for noops on x86. // E.g. nopw 0x0(%rax,%rax,1) is 9 bytes, but re-encoded it's only // 5 bytes. Preserve the size info using annotations. MIB->setSize(Instruction, Size); } addInstruction(Offset, std::move(Instruction)); } for (auto [Offset, Label] : InstructionLabels) { InstrMapType::iterator II = Instructions.find(Offset); assert(II != Instructions.end() && "reference to non-existing instruction"); BC.MIB->setInstLabel(II->second, Label); } // Reset symbolizer for the disassembler. BC.SymbolicDisAsm->setSymbolizer(nullptr); if (uint64_t Offset = getFirstInstructionOffset()) Labels[Offset] = BC.Ctx->createNamedTempSymbol(); clearList(Relocations); if (!IsSimple) { clearList(Instructions); return createNonFatalBOLTError(""); } updateState(State::Disassembled); return Error::success(); } MCSymbol *BinaryFunction::registerBranch(uint64_t Src, uint64_t Dst) { assert(CurrentState == State::Disassembled && "Cannot register branch unless function is in disassembled state."); assert(containsAddress(Src) && containsAddress(Dst) && "Cannot register external branch."); MCSymbol *Target = getOrCreateLocalLabel(Dst); TakenBranches.emplace_back(Src - getAddress(), Dst - getAddress()); return Target; } void BinaryFunction::analyzeInstructionForFuncReference(const MCInst &Inst) { for (const MCOperand &Op : MCPlus::primeOperands(Inst)) { if (!Op.isExpr()) continue; const MCExpr &Expr = *Op.getExpr(); if (Expr.getKind() != MCExpr::SymbolRef) continue; const MCSymbol &Symbol = cast(Expr).getSymbol(); // Set HasAddressTaken for a function regardless of the ICF level. if (BinaryFunction *BF = BC.getFunctionForSymbol(&Symbol)) BF->setHasAddressTaken(true); } } bool BinaryFunction::scanExternalRefs() { bool Success = true; bool DisassemblyFailed = false; // Ignore pseudo functions. if (isPseudo()) return Success; if (opts::NoScan) { clearList(Relocations); clearList(ExternallyReferencedOffsets); return false; } // List of external references for this function. std::vector FunctionRelocations; static BinaryContext::IndependentCodeEmitter Emitter = BC.createIndependentMCCodeEmitter(); ErrorOr> ErrorOrFunctionData = getData(); assert(ErrorOrFunctionData && "function data is not available"); ArrayRef FunctionData = *ErrorOrFunctionData; assert(FunctionData.size() == getMaxSize() && "function size does not match raw data size"); BC.SymbolicDisAsm->setSymbolizer( BC.MIB->createTargetSymbolizer(*this, /*CreateSymbols*/ false)); // Disassemble contents of the function. Detect code entry points and create // relocations for references to code that will be moved. uint64_t Size = 0; // instruction size for (uint64_t Offset = 0; Offset < getSize(); Offset += Size) { // Check for data inside code and ignore it if (const size_t DataInCodeSize = getSizeOfDataInCodeAt(Offset)) { Size = DataInCodeSize; continue; } const uint64_t AbsoluteInstrAddr = getAddress() + Offset; MCInst Instruction; if (!BC.SymbolicDisAsm->getInstruction(Instruction, Size, FunctionData.slice(Offset), AbsoluteInstrAddr, nulls())) { if (opts::Verbosity >= 1 && !isZeroPaddingAt(Offset)) { BC.errs() << "BOLT-WARNING: unable to disassemble instruction at offset 0x" << Twine::utohexstr(Offset) << " (address 0x" << Twine::utohexstr(AbsoluteInstrAddr) << ") in function " << *this << '\n'; } Success = false; DisassemblyFailed = true; break; } // Return true if we can skip handling the Target function reference. auto ignoreFunctionRef = [&](const BinaryFunction &Target) { if (&Target == this) return true; // Note that later we may decide not to emit Target function. In that // case, we conservatively create references that will be ignored or // resolved to the same function. if (!BC.shouldEmit(Target)) return true; return false; }; // Return true if we can ignore reference to the symbol. auto ignoreReference = [&](const MCSymbol *TargetSymbol) { if (!TargetSymbol) return true; if (BC.forceSymbolRelocations(TargetSymbol->getName())) return false; BinaryFunction *TargetFunction = BC.getFunctionForSymbol(TargetSymbol); if (!TargetFunction) return true; return ignoreFunctionRef(*TargetFunction); }; // Handle calls and branches separately as symbolization doesn't work for // them yet. MCSymbol *BranchTargetSymbol = nullptr; if (BC.MIB->isCall(Instruction) || BC.MIB->isBranch(Instruction)) { uint64_t TargetAddress = 0; BC.MIB->evaluateBranch(Instruction, AbsoluteInstrAddr, Size, TargetAddress); // Create an entry point at reference address if needed. BinaryFunction *TargetFunction = BC.getBinaryFunctionContainingAddress(TargetAddress); if (!TargetFunction || ignoreFunctionRef(*TargetFunction)) continue; const uint64_t FunctionOffset = TargetAddress - TargetFunction->getAddress(); BranchTargetSymbol = FunctionOffset ? TargetFunction->addEntryPointAtOffset(FunctionOffset) : TargetFunction->getSymbol(); } // Can't find more references. Not creating relocations since we are not // moving code. if (!BC.HasRelocations) continue; if (BranchTargetSymbol) { BC.MIB->replaceBranchTarget(Instruction, BranchTargetSymbol, Emitter.LocalCtx.get()); } else if (!llvm::any_of(Instruction, [](const MCOperand &Op) { return Op.isExpr(); })) { // Skip assembly if the instruction may not have any symbolic operands. continue; } else { analyzeInstructionForFuncReference(Instruction); } // Emit the instruction using temp emitter and generate relocations. SmallString<256> Code; SmallVector Fixups; Emitter.MCE->encodeInstruction(Instruction, Code, Fixups, *BC.STI); // Create relocation for every fixup. for (const MCFixup &Fixup : Fixups) { std::optional Rel = BC.MIB->createRelocation(Fixup, *BC.MAB); if (!Rel) { Success = false; continue; } if (ignoreReference(Rel->Symbol)) continue; if (Relocation::getSizeForType(Rel->Type) < 4) { // If the instruction uses a short form, then we might not be able // to handle the rewrite without relaxation, and hence cannot reliably // create an external reference relocation. Success = false; continue; } Rel->Offset += getAddress() - getOriginSection()->getAddress() + Offset; FunctionRelocations.push_back(*Rel); } if (!Success) break; } // Reset symbolizer for the disassembler. BC.SymbolicDisAsm->setSymbolizer(nullptr); // Add relocations unless disassembly failed for this function. if (!DisassemblyFailed) for (Relocation &Rel : FunctionRelocations) getOriginSection()->addPendingRelocation(Rel); // Inform BinaryContext that this function symbols will not be defined and // relocations should not be created against them. if (BC.HasRelocations) { for (std::pair &LI : Labels) BC.UndefinedSymbols.insert(LI.second); for (MCSymbol *const EndLabel : FunctionEndLabels) if (EndLabel) BC.UndefinedSymbols.insert(EndLabel); } clearList(Relocations); clearList(ExternallyReferencedOffsets); if (Success && BC.HasRelocations) HasExternalRefRelocations = true; if (opts::Verbosity >= 1 && !Success) BC.outs() << "BOLT-INFO: failed to scan refs for " << *this << '\n'; return Success; } void BinaryFunction::postProcessEntryPoints() { if (!isSimple()) return; for (auto &KV : Labels) { MCSymbol *Label = KV.second; if (!getSecondaryEntryPointSymbol(Label)) continue; // In non-relocation mode there's potentially an external undetectable // reference to the entry point and hence we cannot move this entry // point. Optimizing without moving could be difficult. // In BAT mode, register any known entry points for CFG construction. if (!BC.HasRelocations && !BC.HasBATSection) setSimple(false); const uint32_t Offset = KV.first; // If we are at Offset 0 and there is no instruction associated with it, // this means this is an empty function. Just ignore. If we find an // instruction at this offset, this entry point is valid. if (!Offset || getInstructionAtOffset(Offset)) continue; // On AArch64 there are legitimate reasons to have references past the // end of the function, e.g. jump tables. if (BC.isAArch64() && Offset == getSize()) continue; BC.errs() << "BOLT-WARNING: reference in the middle of instruction " "detected in function " << *this << " at offset 0x" << Twine::utohexstr(Offset) << '\n'; if (BC.HasRelocations) setIgnored(); setSimple(false); return; } } void BinaryFunction::postProcessJumpTables() { // Create labels for all entries. for (auto &JTI : JumpTables) { JumpTable &JT = *JTI.second; if (JT.Type == JumpTable::JTT_PIC && opts::JumpTables == JTS_BASIC) { opts::JumpTables = JTS_MOVE; BC.outs() << "BOLT-INFO: forcing -jump-tables=move as PIC jump table was " "detected in function " << *this << '\n'; } const uint64_t BDSize = BC.getBinaryDataAtAddress(JT.getAddress())->getSize(); if (!BDSize) { BC.setBinaryDataSize(JT.getAddress(), JT.getSize()); } else { assert(BDSize >= JT.getSize() && "jump table cannot be larger than the containing object"); } if (!JT.Entries.empty()) continue; bool HasOneParent = (JT.Parents.size() == 1); for (uint64_t EntryAddress : JT.EntriesAsAddress) { // builtin_unreachable does not belong to any function // Need to handle separately bool IsBuiltinUnreachable = llvm::any_of(JT.Parents, [&](const BinaryFunction *Parent) { return EntryAddress == Parent->getAddress() + Parent->getSize(); }); if (IsBuiltinUnreachable) { MCSymbol *Label = getOrCreateLocalLabel(EntryAddress, true); JT.Entries.push_back(Label); continue; } // Create a local label for targets that cannot be reached by other // fragments. Otherwise, create a secondary entry point in the target // function. BinaryFunction *TargetBF = BC.getBinaryFunctionContainingAddress(EntryAddress); MCSymbol *Label; if (HasOneParent && TargetBF == this) { Label = getOrCreateLocalLabel(EntryAddress, true); } else { const uint64_t Offset = EntryAddress - TargetBF->getAddress(); Label = Offset ? TargetBF->addEntryPointAtOffset(Offset) : TargetBF->getSymbol(); } JT.Entries.push_back(Label); } } // Add TakenBranches from JumpTables. // // We want to do it after initial processing since we don't know jump tables' // boundaries until we process them all. for (auto &JTSite : JTSites) { const uint64_t JTSiteOffset = JTSite.first; const uint64_t JTAddress = JTSite.second; const JumpTable *JT = getJumpTableContainingAddress(JTAddress); assert(JT && "cannot find jump table for address"); uint64_t EntryOffset = JTAddress - JT->getAddress(); while (EntryOffset < JT->getSize()) { uint64_t EntryAddress = JT->EntriesAsAddress[EntryOffset / JT->EntrySize]; uint64_t TargetOffset = EntryAddress - getAddress(); if (TargetOffset < getSize()) { TakenBranches.emplace_back(JTSiteOffset, TargetOffset); if (opts::StrictMode) registerReferencedOffset(TargetOffset); } EntryOffset += JT->EntrySize; // A label at the next entry means the end of this jump table. if (JT->Labels.count(EntryOffset)) break; } } clearList(JTSites); // Conservatively populate all possible destinations for unknown indirect // branches. if (opts::StrictMode && hasInternalReference()) { for (uint64_t Offset : UnknownIndirectBranchOffsets) { for (uint64_t PossibleDestination : ExternallyReferencedOffsets) { // Ignore __builtin_unreachable(). if (PossibleDestination == getSize()) continue; TakenBranches.emplace_back(Offset, PossibleDestination); } } } } bool BinaryFunction::validateExternallyReferencedOffsets() { SmallPtrSet JTTargets; for (const JumpTable *JT : llvm::make_second_range(JumpTables)) JTTargets.insert(JT->Entries.begin(), JT->Entries.end()); bool HasUnclaimedReference = false; for (uint64_t Destination : ExternallyReferencedOffsets) { // Ignore __builtin_unreachable(). if (Destination == getSize()) continue; // Ignore constant islands if (isInConstantIsland(Destination + getAddress())) continue; if (BinaryBasicBlock *BB = getBasicBlockAtOffset(Destination)) { // Check if the externally referenced offset is a recognized jump table // target. if (JTTargets.contains(BB->getLabel())) continue; if (opts::Verbosity >= 1) { BC.errs() << "BOLT-WARNING: unclaimed data to code reference (possibly " << "an unrecognized jump table entry) to " << BB->getName() << " in " << *this << "\n"; } auto L = BC.scopeLock(); addEntryPoint(*BB); } else { BC.errs() << "BOLT-WARNING: unknown data to code reference to offset " << Twine::utohexstr(Destination) << " in " << *this << "\n"; setIgnored(); } HasUnclaimedReference = true; } return !HasUnclaimedReference; } bool BinaryFunction::postProcessIndirectBranches( MCPlusBuilder::AllocatorIdTy AllocId) { auto addUnknownControlFlow = [&](BinaryBasicBlock &BB) { LLVM_DEBUG(dbgs() << "BOLT-DEBUG: adding unknown control flow in " << *this << " for " << BB.getName() << "\n"); HasUnknownControlFlow = true; BB.removeAllSuccessors(); for (uint64_t PossibleDestination : ExternallyReferencedOffsets) if (BinaryBasicBlock *SuccBB = getBasicBlockAtOffset(PossibleDestination)) BB.addSuccessor(SuccBB); }; uint64_t NumIndirectJumps = 0; MCInst *LastIndirectJump = nullptr; BinaryBasicBlock *LastIndirectJumpBB = nullptr; uint64_t LastJT = 0; uint16_t LastJTIndexReg = BC.MIB->getNoRegister(); for (BinaryBasicBlock &BB : blocks()) { for (BinaryBasicBlock::iterator II = BB.begin(); II != BB.end(); ++II) { MCInst &Instr = *II; if (!BC.MIB->isIndirectBranch(Instr)) continue; // If there's an indirect branch in a single-block function - // it must be a tail call. if (BasicBlocks.size() == 1) { BC.MIB->convertJmpToTailCall(Instr); return true; } ++NumIndirectJumps; if (opts::StrictMode && !hasInternalReference()) { BC.MIB->convertJmpToTailCall(Instr); break; } // Validate the tail call or jump table assumptions now that we know // basic block boundaries. if (BC.MIB->isTailCall(Instr) || BC.MIB->getJumpTable(Instr)) { const unsigned PtrSize = BC.AsmInfo->getCodePointerSize(); MCInst *MemLocInstr; unsigned BaseRegNum, IndexRegNum; int64_t DispValue; const MCExpr *DispExpr; MCInst *PCRelBaseInstr; MCInst *FixedEntryLoadInstr; IndirectBranchType Type = BC.MIB->analyzeIndirectBranch( Instr, BB.begin(), II, PtrSize, MemLocInstr, BaseRegNum, IndexRegNum, DispValue, DispExpr, PCRelBaseInstr, FixedEntryLoadInstr); if (Type != IndirectBranchType::UNKNOWN || MemLocInstr != nullptr) continue; if (!opts::StrictMode) return false; if (BC.MIB->isTailCall(Instr)) { BC.MIB->convertTailCallToJmp(Instr); } else { LastIndirectJump = &Instr; LastIndirectJumpBB = &BB; LastJT = BC.MIB->getJumpTable(Instr); LastJTIndexReg = BC.MIB->getJumpTableIndexReg(Instr); BC.MIB->unsetJumpTable(Instr); JumpTable *JT = BC.getJumpTableContainingAddress(LastJT); if (JT->Type == JumpTable::JTT_NORMAL) { // Invalidating the jump table may also invalidate other jump table // boundaries. Until we have/need a support for this, mark the // function as non-simple. LLVM_DEBUG(dbgs() << "BOLT-DEBUG: rejected jump table reference" << JT->getName() << " in " << *this << '\n'); return false; } } addUnknownControlFlow(BB); continue; } // If this block contains an epilogue code and has an indirect branch, // then most likely it's a tail call. Otherwise, we cannot tell for sure // what it is and conservatively reject the function's CFG. bool IsEpilogue = llvm::any_of(BB, [&](const MCInst &Instr) { return BC.MIB->isLeave(Instr) || BC.MIB->isPop(Instr); }); if (IsEpilogue) { BC.MIB->convertJmpToTailCall(Instr); BB.removeAllSuccessors(); continue; } if (opts::Verbosity >= 2) { BC.outs() << "BOLT-INFO: rejected potential indirect tail call in " << "function " << *this << " in basic block " << BB.getName() << ".\n"; LLVM_DEBUG(BC.printInstructions(dbgs(), BB.begin(), BB.end(), BB.getOffset(), this, true)); } if (!opts::StrictMode) return false; addUnknownControlFlow(BB); } } if (HasInternalLabelReference) return false; // If there's only one jump table, and one indirect jump, and no other // references, then we should be able to derive the jump table even if we // fail to match the pattern. if (HasUnknownControlFlow && NumIndirectJumps == 1 && JumpTables.size() == 1 && LastIndirectJump && !BC.getJumpTableContainingAddress(LastJT)->IsSplit) { LLVM_DEBUG(dbgs() << "BOLT-DEBUG: unsetting unknown control flow in " << *this << '\n'); BC.MIB->setJumpTable(*LastIndirectJump, LastJT, LastJTIndexReg, AllocId); HasUnknownControlFlow = false; LastIndirectJumpBB->updateJumpTableSuccessors(); } // Validate that all data references to function offsets are claimed by // recognized jump tables. Register externally referenced blocks as entry // points. if (!opts::StrictMode && hasInternalReference()) { if (!validateExternallyReferencedOffsets()) return false; } if (HasUnknownControlFlow && !BC.HasRelocations) return false; return true; } void BinaryFunction::recomputeLandingPads() { updateBBIndices(0); for (BinaryBasicBlock *BB : BasicBlocks) { BB->LandingPads.clear(); BB->Throwers.clear(); } for (BinaryBasicBlock *BB : BasicBlocks) { std::unordered_set BBLandingPads; for (MCInst &Instr : *BB) { if (!BC.MIB->isInvoke(Instr)) continue; const std::optional EHInfo = BC.MIB->getEHInfo(Instr); if (!EHInfo || !EHInfo->first) continue; BinaryBasicBlock *LPBlock = getBasicBlockForLabel(EHInfo->first); if (!BBLandingPads.count(LPBlock)) { BBLandingPads.insert(LPBlock); BB->LandingPads.emplace_back(LPBlock); LPBlock->Throwers.emplace_back(BB); } } } } Error BinaryFunction::buildCFG(MCPlusBuilder::AllocatorIdTy AllocatorId) { auto &MIB = BC.MIB; if (!isSimple()) { assert(!BC.HasRelocations && "cannot process file with non-simple function in relocs mode"); return createNonFatalBOLTError(""); } if (CurrentState != State::Disassembled) return createNonFatalBOLTError(""); assert(BasicBlocks.empty() && "basic block list should be empty"); assert((Labels.find(getFirstInstructionOffset()) != Labels.end()) && "first instruction should always have a label"); // Create basic blocks in the original layout order: // // * Every instruction with associated label marks // the beginning of a basic block. // * Conditional instruction marks the end of a basic block, // except when the following instruction is an // unconditional branch, and the unconditional branch is not // a destination of another branch. In the latter case, the // basic block will consist of a single unconditional branch // (missed "double-jump" optimization). // // Created basic blocks are sorted in layout order since they are // created in the same order as instructions, and instructions are // sorted by offsets. BinaryBasicBlock *InsertBB = nullptr; BinaryBasicBlock *PrevBB = nullptr; bool IsLastInstrNop = false; // Offset of the last non-nop instruction. uint64_t LastInstrOffset = 0; auto addCFIPlaceholders = [this](uint64_t CFIOffset, BinaryBasicBlock *InsertBB) { for (auto FI = OffsetToCFI.lower_bound(CFIOffset), FE = OffsetToCFI.upper_bound(CFIOffset); FI != FE; ++FI) { addCFIPseudo(InsertBB, InsertBB->end(), FI->second); } }; // For profiling purposes we need to save the offset of the last instruction // in the basic block. // NOTE: nops always have an Offset annotation. Annotate the last non-nop as // older profiles ignored nops. auto updateOffset = [&](uint64_t Offset) { assert(PrevBB && PrevBB != InsertBB && "invalid previous block"); MCInst *LastNonNop = nullptr; for (BinaryBasicBlock::reverse_iterator RII = PrevBB->getLastNonPseudo(), E = PrevBB->rend(); RII != E; ++RII) { if (!BC.MIB->isPseudo(*RII) && !BC.MIB->isNoop(*RII)) { LastNonNop = &*RII; break; } } if (LastNonNop && !MIB->getOffset(*LastNonNop)) MIB->setOffset(*LastNonNop, static_cast(Offset)); }; for (auto I = Instructions.begin(), E = Instructions.end(); I != E; ++I) { const uint32_t Offset = I->first; MCInst &Instr = I->second; auto LI = Labels.find(Offset); if (LI != Labels.end()) { // Always create new BB at branch destination. PrevBB = InsertBB ? InsertBB : PrevBB; InsertBB = addBasicBlockAt(LI->first, LI->second); if (opts::PreserveBlocksAlignment && IsLastInstrNop) InsertBB->setDerivedAlignment(); if (PrevBB) updateOffset(LastInstrOffset); } // Mark all nops with Offset for profile tracking purposes. if (MIB->isNoop(Instr) && !MIB->getOffset(Instr)) { // If "Offset" annotation is not present, set it and mark the nop for // deletion. MIB->setOffset(Instr, static_cast(Offset)); // Annotate ordinary nops, so we can safely delete them if required. MIB->addAnnotation(Instr, "NOP", static_cast(1), AllocatorId); } if (!InsertBB) { // It must be a fallthrough or unreachable code. Create a new block unless // we see an unconditional branch following a conditional one. The latter // should not be a conditional tail call. assert(PrevBB && "no previous basic block for a fall through"); MCInst *PrevInstr = PrevBB->getLastNonPseudoInstr(); assert(PrevInstr && "no previous instruction for a fall through"); if (MIB->isUnconditionalBranch(Instr) && !MIB->isIndirectBranch(*PrevInstr) && !MIB->isUnconditionalBranch(*PrevInstr) && !MIB->getConditionalTailCall(*PrevInstr) && !MIB->isReturn(*PrevInstr)) { // Temporarily restore inserter basic block. InsertBB = PrevBB; } else { MCSymbol *Label; { auto L = BC.scopeLock(); Label = BC.Ctx->createNamedTempSymbol("FT"); } InsertBB = addBasicBlockAt(Offset, Label); if (opts::PreserveBlocksAlignment && IsLastInstrNop) InsertBB->setDerivedAlignment(); updateOffset(LastInstrOffset); } } if (Offset == getFirstInstructionOffset()) { // Add associated CFI pseudos in the first offset addCFIPlaceholders(Offset, InsertBB); } const bool IsBlockEnd = MIB->isTerminator(Instr); IsLastInstrNop = MIB->isNoop(Instr); if (!IsLastInstrNop) LastInstrOffset = Offset; InsertBB->addInstruction(std::move(Instr)); // Add associated CFI instrs. We always add the CFI instruction that is // located immediately after this instruction, since the next CFI // instruction reflects the change in state caused by this instruction. auto NextInstr = std::next(I); uint64_t CFIOffset; if (NextInstr != E) CFIOffset = NextInstr->first; else CFIOffset = getSize(); // Note: this potentially invalidates instruction pointers/iterators. addCFIPlaceholders(CFIOffset, InsertBB); if (IsBlockEnd) { PrevBB = InsertBB; InsertBB = nullptr; } } if (BasicBlocks.empty()) { setSimple(false); return createNonFatalBOLTError(""); } // Intermediate dump. LLVM_DEBUG(print(dbgs(), "after creating basic blocks")); // TODO: handle properly calls to no-return functions, // e.g. exit(3), etc. Otherwise we'll see a false fall-through // blocks. // Remove duplicates branches. We can get a bunch of them from jump tables. // Without doing jump table value profiling we don't have a use for extra // (duplicate) branches. llvm::sort(TakenBranches); auto NewEnd = std::unique(TakenBranches.begin(), TakenBranches.end()); TakenBranches.erase(NewEnd, TakenBranches.end()); for (std::pair &Branch : TakenBranches) { LLVM_DEBUG(dbgs() << "registering branch [0x" << Twine::utohexstr(Branch.first) << "] -> [0x" << Twine::utohexstr(Branch.second) << "]\n"); BinaryBasicBlock *FromBB = getBasicBlockContainingOffset(Branch.first); BinaryBasicBlock *ToBB = getBasicBlockAtOffset(Branch.second); if (!FromBB || !ToBB) { if (!FromBB) BC.errs() << "BOLT-ERROR: cannot find BB containing the branch.\n"; if (!ToBB) BC.errs() << "BOLT-ERROR: cannot find BB containing branch destination.\n"; return createFatalBOLTError(BC.generateBugReportMessage( "disassembly failed - inconsistent branch found.", *this)); } FromBB->addSuccessor(ToBB); } // Add fall-through branches. PrevBB = nullptr; bool IsPrevFT = false; // Is previous block a fall-through. for (BinaryBasicBlock *BB : BasicBlocks) { if (IsPrevFT) PrevBB->addSuccessor(BB); if (BB->empty()) { IsPrevFT = true; PrevBB = BB; continue; } MCInst *LastInstr = BB->getLastNonPseudoInstr(); assert(LastInstr && "should have non-pseudo instruction in non-empty block"); if (BB->succ_size() == 0) { // Since there's no existing successors, we know the last instruction is // not a conditional branch. Thus if it's a terminator, it shouldn't be a // fall-through. // // Conditional tail call is a special case since we don't add a taken // branch successor for it. IsPrevFT = !MIB->isTerminator(*LastInstr) || MIB->getConditionalTailCall(*LastInstr); } else if (BB->succ_size() == 1) { IsPrevFT = MIB->isConditionalBranch(*LastInstr); } else { IsPrevFT = false; } PrevBB = BB; } // Assign landing pads and throwers info. recomputeLandingPads(); // Assign CFI information to each BB entry. annotateCFIState(); // Annotate invoke instructions with GNU_args_size data. propagateGnuArgsSizeInfo(AllocatorId); // Set the basic block layout to the original order and set end offsets. PrevBB = nullptr; for (BinaryBasicBlock *BB : BasicBlocks) { Layout.addBasicBlock(BB); if (PrevBB) PrevBB->setEndOffset(BB->getOffset()); PrevBB = BB; } PrevBB->setEndOffset(getSize()); Layout.updateLayoutIndices(); normalizeCFIState(); // Clean-up memory taken by intermediate structures. // // NB: don't clear Labels list as we may need them if we mark the function // as non-simple later in the process of discovering extra entry points. clearList(Instructions); clearList(OffsetToCFI); clearList(TakenBranches); // Update the state. CurrentState = State::CFG; // Make any necessary adjustments for indirect branches. if (!postProcessIndirectBranches(AllocatorId)) { if (opts::Verbosity) { BC.errs() << "BOLT-WARNING: failed to post-process indirect branches for " << *this << '\n'; } if (BC.isAArch64()) PreserveNops = BC.HasRelocations; // In relocation mode we want to keep processing the function but avoid // optimizing it. setSimple(false); } clearList(ExternallyReferencedOffsets); clearList(UnknownIndirectBranchOffsets); return Error::success(); } void BinaryFunction::postProcessCFG() { if (isSimple() && !BasicBlocks.empty()) { // Convert conditional tail call branches to conditional branches that jump // to a tail call. removeConditionalTailCalls(); postProcessProfile(); // Eliminate inconsistencies between branch instructions and CFG. postProcessBranches(); } // The final cleanup of intermediate structures. clearList(IgnoredBranches); // Remove "Offset" annotations, unless we need an address-translation table // later. This has no cost, since annotations are allocated by a bumpptr // allocator and won't be released anyway until late in the pipeline. if (!requiresAddressTranslation() && !opts::Instrument) { for (BinaryBasicBlock &BB : blocks()) for (MCInst &Inst : BB) BC.MIB->clearOffset(Inst); } assert((!isSimple() || validateCFG()) && "invalid CFG detected after post-processing"); } void BinaryFunction::removeTagsFromProfile() { for (BinaryBasicBlock *BB : BasicBlocks) { if (BB->ExecutionCount == BinaryBasicBlock::COUNT_NO_PROFILE) BB->ExecutionCount = 0; for (BinaryBasicBlock::BinaryBranchInfo &BI : BB->branch_info()) { if (BI.Count != BinaryBasicBlock::COUNT_NO_PROFILE && BI.MispredictedCount != BinaryBasicBlock::COUNT_NO_PROFILE) continue; BI.Count = 0; BI.MispredictedCount = 0; } } } void BinaryFunction::removeConditionalTailCalls() { // Blocks to be appended at the end. std::vector> NewBlocks; for (auto BBI = begin(); BBI != end(); ++BBI) { BinaryBasicBlock &BB = *BBI; MCInst *CTCInstr = BB.getLastNonPseudoInstr(); if (!CTCInstr) continue; std::optional TargetAddressOrNone = BC.MIB->getConditionalTailCall(*CTCInstr); if (!TargetAddressOrNone) continue; // Gather all necessary information about CTC instruction before // annotations are destroyed. const int32_t CFIStateBeforeCTC = BB.getCFIStateAtInstr(CTCInstr); uint64_t CTCTakenCount = BinaryBasicBlock::COUNT_NO_PROFILE; uint64_t CTCMispredCount = BinaryBasicBlock::COUNT_NO_PROFILE; if (hasValidProfile()) { CTCTakenCount = BC.MIB->getAnnotationWithDefault( *CTCInstr, "CTCTakenCount"); CTCMispredCount = BC.MIB->getAnnotationWithDefault( *CTCInstr, "CTCMispredCount"); } // Assert that the tail call does not throw. assert(!BC.MIB->getEHInfo(*CTCInstr) && "found tail call with associated landing pad"); // Create a basic block with an unconditional tail call instruction using // the same destination. const MCSymbol *CTCTargetLabel = BC.MIB->getTargetSymbol(*CTCInstr); assert(CTCTargetLabel && "symbol expected for conditional tail call"); MCInst TailCallInstr; BC.MIB->createTailCall(TailCallInstr, CTCTargetLabel, BC.Ctx.get()); // Move offset from CTCInstr to TailCallInstr. if (const std::optional Offset = BC.MIB->getOffset(*CTCInstr)) { BC.MIB->setOffset(TailCallInstr, *Offset); BC.MIB->clearOffset(*CTCInstr); } // Link new BBs to the original input offset of the BB where the CTC // is, so we can map samples recorded in new BBs back to the original BB // seem in the input binary (if using BAT) std::unique_ptr TailCallBB = createBasicBlock(BC.Ctx->createNamedTempSymbol("TC")); TailCallBB->setOffset(BB.getInputOffset()); TailCallBB->addInstruction(TailCallInstr); TailCallBB->setCFIState(CFIStateBeforeCTC); // Add CFG edge with profile info from BB to TailCallBB. BB.addSuccessor(TailCallBB.get(), CTCTakenCount, CTCMispredCount); // Add execution count for the block. TailCallBB->setExecutionCount(CTCTakenCount); BC.MIB->convertTailCallToJmp(*CTCInstr); BC.MIB->replaceBranchTarget(*CTCInstr, TailCallBB->getLabel(), BC.Ctx.get()); // Add basic block to the list that will be added to the end. NewBlocks.emplace_back(std::move(TailCallBB)); // Swap edges as the TailCallBB corresponds to the taken branch. BB.swapConditionalSuccessors(); // This branch is no longer a conditional tail call. BC.MIB->unsetConditionalTailCall(*CTCInstr); } insertBasicBlocks(std::prev(end()), std::move(NewBlocks), /* UpdateLayout */ true, /* UpdateCFIState */ false); } uint64_t BinaryFunction::getFunctionScore() const { if (FunctionScore != -1) return FunctionScore; if (!isSimple() || !hasValidProfile()) { FunctionScore = 0; return FunctionScore; } uint64_t TotalScore = 0ULL; for (const BinaryBasicBlock &BB : blocks()) { uint64_t BBExecCount = BB.getExecutionCount(); if (BBExecCount == BinaryBasicBlock::COUNT_NO_PROFILE) continue; TotalScore += BBExecCount * BB.getNumNonPseudos(); } FunctionScore = TotalScore; return FunctionScore; } void BinaryFunction::annotateCFIState() { assert(CurrentState == State::Disassembled && "unexpected function state"); assert(!BasicBlocks.empty() && "basic block list should not be empty"); // This is an index of the last processed CFI in FDE CFI program. uint32_t State = 0; // This is an index of RememberState CFI reflecting effective state right // after execution of RestoreState CFI. // // It differs from State iff the CFI at (State-1) // was RestoreState (modulo GNU_args_size CFIs, which are ignored). // // This allows us to generate shorter replay sequences when producing new // CFI programs. uint32_t EffectiveState = 0; // For tracking RememberState/RestoreState sequences. std::stack StateStack; for (BinaryBasicBlock *BB : BasicBlocks) { BB->setCFIState(EffectiveState); for (const MCInst &Instr : *BB) { const MCCFIInstruction *CFI = getCFIFor(Instr); if (!CFI) continue; ++State; switch (CFI->getOperation()) { case MCCFIInstruction::OpRememberState: StateStack.push(EffectiveState); EffectiveState = State; break; case MCCFIInstruction::OpRestoreState: assert(!StateStack.empty() && "corrupt CFI stack"); EffectiveState = StateStack.top(); StateStack.pop(); break; case MCCFIInstruction::OpGnuArgsSize: // OpGnuArgsSize CFIs do not affect the CFI state. break; default: // Any other CFI updates the state. EffectiveState = State; break; } } } if (opts::Verbosity >= 1 && !StateStack.empty()) { BC.errs() << "BOLT-WARNING: non-empty CFI stack at the end of " << *this << '\n'; } } namespace { /// Our full interpretation of a DWARF CFI machine state at a given point struct CFISnapshot { /// CFA register number and offset defining the canonical frame at this /// point, or the number of a rule (CFI state) that computes it with a /// DWARF expression. This number will be negative if it refers to a CFI /// located in the CIE instead of the FDE. uint32_t CFAReg; int32_t CFAOffset; int32_t CFARule; /// Mapping of rules (CFI states) that define the location of each /// register. If absent, no rule defining the location of such register /// was ever read. This number will be negative if it refers to a CFI /// located in the CIE instead of the FDE. DenseMap RegRule; /// References to CIE, FDE and expanded instructions after a restore state const BinaryFunction::CFIInstrMapType &CIE; const BinaryFunction::CFIInstrMapType &FDE; const DenseMap> &FrameRestoreEquivalents; /// Current FDE CFI number representing the state where the snapshot is at int32_t CurState; /// Used when we don't have information about which state/rule to apply /// to recover the location of either the CFA or a specific register constexpr static int32_t UNKNOWN = std::numeric_limits::min(); private: /// Update our snapshot by executing a single CFI void update(const MCCFIInstruction &Instr, int32_t RuleNumber) { switch (Instr.getOperation()) { case MCCFIInstruction::OpSameValue: case MCCFIInstruction::OpRelOffset: case MCCFIInstruction::OpOffset: case MCCFIInstruction::OpRestore: case MCCFIInstruction::OpUndefined: case MCCFIInstruction::OpRegister: RegRule[Instr.getRegister()] = RuleNumber; break; case MCCFIInstruction::OpDefCfaRegister: CFAReg = Instr.getRegister(); CFARule = UNKNOWN; // This shouldn't happen according to the spec but GNU binutils on RISC-V // emits a DW_CFA_def_cfa_register in CIE's which leaves the offset // unspecified. Both readelf and llvm-dwarfdump interpret the offset as 0 // in this case so let's do the same. if (CFAOffset == UNKNOWN) CFAOffset = 0; break; case MCCFIInstruction::OpDefCfaOffset: CFAOffset = Instr.getOffset(); CFARule = UNKNOWN; break; case MCCFIInstruction::OpDefCfa: CFAReg = Instr.getRegister(); CFAOffset = Instr.getOffset(); CFARule = UNKNOWN; break; case MCCFIInstruction::OpEscape: { std::optional Reg = readDWARFExpressionTargetReg(Instr.getValues()); // Handle DW_CFA_def_cfa_expression if (!Reg) { CFARule = RuleNumber; break; } RegRule[*Reg] = RuleNumber; break; } case MCCFIInstruction::OpAdjustCfaOffset: case MCCFIInstruction::OpWindowSave: case MCCFIInstruction::OpNegateRAState: case MCCFIInstruction::OpNegateRAStateWithPC: case MCCFIInstruction::OpLLVMDefAspaceCfa: case MCCFIInstruction::OpLabel: case MCCFIInstruction::OpValOffset: llvm_unreachable("unsupported CFI opcode"); break; case MCCFIInstruction::OpRememberState: case MCCFIInstruction::OpRestoreState: case MCCFIInstruction::OpGnuArgsSize: // do not affect CFI state break; } } public: /// Advance state reading FDE CFI instructions up to State number void advanceTo(int32_t State) { for (int32_t I = CurState, E = State; I != E; ++I) { const MCCFIInstruction &Instr = FDE[I]; if (Instr.getOperation() != MCCFIInstruction::OpRestoreState) { update(Instr, I); continue; } // If restore state instruction, fetch the equivalent CFIs that have // the same effect of this restore. This is used to ensure remember- // restore pairs are completely removed. auto Iter = FrameRestoreEquivalents.find(I); if (Iter == FrameRestoreEquivalents.end()) continue; for (int32_t RuleNumber : Iter->second) update(FDE[RuleNumber], RuleNumber); } assert(((CFAReg != (uint32_t)UNKNOWN && CFAOffset != UNKNOWN) || CFARule != UNKNOWN) && "CIE did not define default CFA?"); CurState = State; } /// Interpret all CIE and FDE instructions up until CFI State number and /// populate this snapshot CFISnapshot( const BinaryFunction::CFIInstrMapType &CIE, const BinaryFunction::CFIInstrMapType &FDE, const DenseMap> &FrameRestoreEquivalents, int32_t State) : CIE(CIE), FDE(FDE), FrameRestoreEquivalents(FrameRestoreEquivalents) { CFAReg = UNKNOWN; CFAOffset = UNKNOWN; CFARule = UNKNOWN; CurState = 0; for (int32_t I = 0, E = CIE.size(); I != E; ++I) { const MCCFIInstruction &Instr = CIE[I]; update(Instr, -I); } advanceTo(State); } }; /// A CFI snapshot with the capability of checking if incremental additions to /// it are redundant. This is used to ensure we do not emit two CFI instructions /// back-to-back that are doing the same state change, or to avoid emitting a /// CFI at all when the state at that point would not be modified after that CFI struct CFISnapshotDiff : public CFISnapshot { bool RestoredCFAReg{false}; bool RestoredCFAOffset{false}; DenseMap RestoredRegs; CFISnapshotDiff(const CFISnapshot &S) : CFISnapshot(S) {} CFISnapshotDiff( const BinaryFunction::CFIInstrMapType &CIE, const BinaryFunction::CFIInstrMapType &FDE, const DenseMap> &FrameRestoreEquivalents, int32_t State) : CFISnapshot(CIE, FDE, FrameRestoreEquivalents, State) {} /// Return true if applying Instr to this state is redundant and can be /// dismissed. bool isRedundant(const MCCFIInstruction &Instr) { switch (Instr.getOperation()) { case MCCFIInstruction::OpSameValue: case MCCFIInstruction::OpRelOffset: case MCCFIInstruction::OpOffset: case MCCFIInstruction::OpRestore: case MCCFIInstruction::OpUndefined: case MCCFIInstruction::OpRegister: case MCCFIInstruction::OpEscape: { uint32_t Reg; if (Instr.getOperation() != MCCFIInstruction::OpEscape) { Reg = Instr.getRegister(); } else { std::optional R = readDWARFExpressionTargetReg(Instr.getValues()); // Handle DW_CFA_def_cfa_expression if (!R) { if (RestoredCFAReg && RestoredCFAOffset) return true; RestoredCFAReg = true; RestoredCFAOffset = true; return false; } Reg = *R; } if (RestoredRegs[Reg]) return true; RestoredRegs[Reg] = true; const int32_t CurRegRule = RegRule.contains(Reg) ? RegRule[Reg] : UNKNOWN; if (CurRegRule == UNKNOWN) { if (Instr.getOperation() == MCCFIInstruction::OpRestore || Instr.getOperation() == MCCFIInstruction::OpSameValue) return true; return false; } const MCCFIInstruction &LastDef = CurRegRule < 0 ? CIE[-CurRegRule] : FDE[CurRegRule]; return LastDef == Instr; } case MCCFIInstruction::OpDefCfaRegister: if (RestoredCFAReg) return true; RestoredCFAReg = true; return CFAReg == Instr.getRegister(); case MCCFIInstruction::OpDefCfaOffset: if (RestoredCFAOffset) return true; RestoredCFAOffset = true; return CFAOffset == Instr.getOffset(); case MCCFIInstruction::OpDefCfa: if (RestoredCFAReg && RestoredCFAOffset) return true; RestoredCFAReg = true; RestoredCFAOffset = true; return CFAReg == Instr.getRegister() && CFAOffset == Instr.getOffset(); case MCCFIInstruction::OpAdjustCfaOffset: case MCCFIInstruction::OpWindowSave: case MCCFIInstruction::OpNegateRAState: case MCCFIInstruction::OpNegateRAStateWithPC: case MCCFIInstruction::OpLLVMDefAspaceCfa: case MCCFIInstruction::OpLabel: case MCCFIInstruction::OpValOffset: llvm_unreachable("unsupported CFI opcode"); return false; case MCCFIInstruction::OpRememberState: case MCCFIInstruction::OpRestoreState: case MCCFIInstruction::OpGnuArgsSize: // do not affect CFI state return true; } return false; } }; } // end anonymous namespace bool BinaryFunction::replayCFIInstrs(int32_t FromState, int32_t ToState, BinaryBasicBlock *InBB, BinaryBasicBlock::iterator InsertIt) { if (FromState == ToState) return true; assert(FromState < ToState && "can only replay CFIs forward"); CFISnapshotDiff CFIDiff(CIEFrameInstructions, FrameInstructions, FrameRestoreEquivalents, FromState); std::vector NewCFIs; for (int32_t CurState = FromState; CurState < ToState; ++CurState) { MCCFIInstruction *Instr = &FrameInstructions[CurState]; if (Instr->getOperation() == MCCFIInstruction::OpRestoreState) { auto Iter = FrameRestoreEquivalents.find(CurState); assert(Iter != FrameRestoreEquivalents.end()); NewCFIs.insert(NewCFIs.end(), Iter->second.begin(), Iter->second.end()); // RestoreState / Remember will be filtered out later by CFISnapshotDiff, // so we might as well fall-through here. } NewCFIs.push_back(CurState); } // Replay instructions while avoiding duplicates for (int32_t State : llvm::reverse(NewCFIs)) { if (CFIDiff.isRedundant(FrameInstructions[State])) continue; InsertIt = addCFIPseudo(InBB, InsertIt, State); } return true; } SmallVector BinaryFunction::unwindCFIState(int32_t FromState, int32_t ToState, BinaryBasicBlock *InBB, BinaryBasicBlock::iterator &InsertIt) { SmallVector NewStates; CFISnapshot ToCFITable(CIEFrameInstructions, FrameInstructions, FrameRestoreEquivalents, ToState); CFISnapshotDiff FromCFITable(ToCFITable); FromCFITable.advanceTo(FromState); auto undoStateDefCfa = [&]() { if (ToCFITable.CFARule == CFISnapshot::UNKNOWN) { FrameInstructions.emplace_back(MCCFIInstruction::cfiDefCfa( nullptr, ToCFITable.CFAReg, ToCFITable.CFAOffset)); if (FromCFITable.isRedundant(FrameInstructions.back())) { FrameInstructions.pop_back(); return; } NewStates.push_back(FrameInstructions.size() - 1); InsertIt = addCFIPseudo(InBB, InsertIt, FrameInstructions.size() - 1); ++InsertIt; } else if (ToCFITable.CFARule < 0) { if (FromCFITable.isRedundant(CIEFrameInstructions[-ToCFITable.CFARule])) return; NewStates.push_back(FrameInstructions.size()); InsertIt = addCFIPseudo(InBB, InsertIt, FrameInstructions.size()); ++InsertIt; FrameInstructions.emplace_back(CIEFrameInstructions[-ToCFITable.CFARule]); } else if (!FromCFITable.isRedundant( FrameInstructions[ToCFITable.CFARule])) { NewStates.push_back(ToCFITable.CFARule); InsertIt = addCFIPseudo(InBB, InsertIt, ToCFITable.CFARule); ++InsertIt; } }; auto undoState = [&](const MCCFIInstruction &Instr) { switch (Instr.getOperation()) { case MCCFIInstruction::OpRememberState: case MCCFIInstruction::OpRestoreState: break; case MCCFIInstruction::OpSameValue: case MCCFIInstruction::OpRelOffset: case MCCFIInstruction::OpOffset: case MCCFIInstruction::OpRestore: case MCCFIInstruction::OpUndefined: case MCCFIInstruction::OpEscape: case MCCFIInstruction::OpRegister: { uint32_t Reg; if (Instr.getOperation() != MCCFIInstruction::OpEscape) { Reg = Instr.getRegister(); } else { std::optional R = readDWARFExpressionTargetReg(Instr.getValues()); // Handle DW_CFA_def_cfa_expression if (!R) { undoStateDefCfa(); return; } Reg = *R; } if (!ToCFITable.RegRule.contains(Reg)) { FrameInstructions.emplace_back( MCCFIInstruction::createRestore(nullptr, Reg)); if (FromCFITable.isRedundant(FrameInstructions.back())) { FrameInstructions.pop_back(); break; } NewStates.push_back(FrameInstructions.size() - 1); InsertIt = addCFIPseudo(InBB, InsertIt, FrameInstructions.size() - 1); ++InsertIt; break; } const int32_t Rule = ToCFITable.RegRule[Reg]; if (Rule < 0) { if (FromCFITable.isRedundant(CIEFrameInstructions[-Rule])) break; NewStates.push_back(FrameInstructions.size()); InsertIt = addCFIPseudo(InBB, InsertIt, FrameInstructions.size()); ++InsertIt; FrameInstructions.emplace_back(CIEFrameInstructions[-Rule]); break; } if (FromCFITable.isRedundant(FrameInstructions[Rule])) break; NewStates.push_back(Rule); InsertIt = addCFIPseudo(InBB, InsertIt, Rule); ++InsertIt; break; } case MCCFIInstruction::OpDefCfaRegister: case MCCFIInstruction::OpDefCfaOffset: case MCCFIInstruction::OpDefCfa: undoStateDefCfa(); break; case MCCFIInstruction::OpAdjustCfaOffset: case MCCFIInstruction::OpWindowSave: case MCCFIInstruction::OpNegateRAState: case MCCFIInstruction::OpNegateRAStateWithPC: case MCCFIInstruction::OpLLVMDefAspaceCfa: case MCCFIInstruction::OpLabel: case MCCFIInstruction::OpValOffset: llvm_unreachable("unsupported CFI opcode"); break; case MCCFIInstruction::OpGnuArgsSize: // do not affect CFI state break; } }; // Undo all modifications from ToState to FromState for (int32_t I = ToState, E = FromState; I != E; ++I) { const MCCFIInstruction &Instr = FrameInstructions[I]; if (Instr.getOperation() != MCCFIInstruction::OpRestoreState) { undoState(Instr); continue; } auto Iter = FrameRestoreEquivalents.find(I); if (Iter == FrameRestoreEquivalents.end()) continue; for (int32_t State : Iter->second) undoState(FrameInstructions[State]); } return NewStates; } void BinaryFunction::normalizeCFIState() { // Reordering blocks with remember-restore state instructions can be specially // tricky. When rewriting the CFI, we omit remember-restore state instructions // entirely. For restore state, we build a map expanding each restore to the // equivalent unwindCFIState sequence required at that point to achieve the // same effect of the restore. All remember state are then just ignored. std::stack Stack; for (BinaryBasicBlock *CurBB : Layout.blocks()) { for (auto II = CurBB->begin(); II != CurBB->end(); ++II) { if (const MCCFIInstruction *CFI = getCFIFor(*II)) { if (CFI->getOperation() == MCCFIInstruction::OpRememberState) { Stack.push(II->getOperand(0).getImm()); continue; } if (CFI->getOperation() == MCCFIInstruction::OpRestoreState) { const int32_t RememberState = Stack.top(); const int32_t CurState = II->getOperand(0).getImm(); FrameRestoreEquivalents[CurState] = unwindCFIState(CurState, RememberState, CurBB, II); Stack.pop(); } } } } } bool BinaryFunction::finalizeCFIState() { LLVM_DEBUG( dbgs() << "Trying to fix CFI states for each BB after reordering.\n"); LLVM_DEBUG(dbgs() << "This is the list of CFI states for each BB of " << *this << ": "); const char *Sep = ""; (void)Sep; for (FunctionFragment &FF : Layout.fragments()) { // Hot-cold border: at start of each region (with a different FDE) we need // to reset the CFI state. int32_t State = 0; for (BinaryBasicBlock *BB : FF) { const int32_t CFIStateAtExit = BB->getCFIStateAtExit(); // We need to recover the correct state if it doesn't match expected // state at BB entry point. if (BB->getCFIState() < State) { // In this case, State is currently higher than what this BB expect it // to be. To solve this, we need to insert CFI instructions to undo // the effect of all CFI from BB's state to current State. auto InsertIt = BB->begin(); unwindCFIState(State, BB->getCFIState(), BB, InsertIt); } else if (BB->getCFIState() > State) { // If BB's CFI state is greater than State, it means we are behind in // the state. Just emit all instructions to reach this state at the // beginning of this BB. If this sequence of instructions involve // remember state or restore state, bail out. if (!replayCFIInstrs(State, BB->getCFIState(), BB, BB->begin())) return false; } State = CFIStateAtExit; LLVM_DEBUG(dbgs() << Sep << State; Sep = ", "); } } LLVM_DEBUG(dbgs() << "\n"); for (BinaryBasicBlock &BB : blocks()) { for (auto II = BB.begin(); II != BB.end();) { const MCCFIInstruction *CFI = getCFIFor(*II); if (CFI && (CFI->getOperation() == MCCFIInstruction::OpRememberState || CFI->getOperation() == MCCFIInstruction::OpRestoreState)) { II = BB.eraseInstruction(II); } else { ++II; } } } return true; } bool BinaryFunction::requiresAddressTranslation() const { return opts::EnableBAT || hasSDTMarker() || hasPseudoProbe(); } bool BinaryFunction::requiresAddressMap() const { if (isInjected()) return false; return opts::UpdateDebugSections || isMultiEntry() || requiresAddressTranslation(); } uint64_t BinaryFunction::getInstructionCount() const { uint64_t Count = 0; for (const BinaryBasicBlock &BB : blocks()) Count += BB.getNumNonPseudos(); return Count; } void BinaryFunction::clearDisasmState() { clearList(Instructions); clearList(IgnoredBranches); clearList(TakenBranches); if (BC.HasRelocations) { for (std::pair &LI : Labels) BC.UndefinedSymbols.insert(LI.second); for (MCSymbol *const EndLabel : FunctionEndLabels) if (EndLabel) BC.UndefinedSymbols.insert(EndLabel); } } void BinaryFunction::setTrapOnEntry() { clearDisasmState(); forEachEntryPoint([&](uint64_t Offset, const MCSymbol *Label) -> bool { MCInst TrapInstr; BC.MIB->createTrap(TrapInstr); addInstruction(Offset, std::move(TrapInstr)); return true; }); TrapsOnEntry = true; } void BinaryFunction::setIgnored() { if (opts::processAllFunctions()) { // We can accept ignored functions before they've been disassembled. // In that case, they would still get disassembled and emited, but not // optimized. assert(CurrentState == State::Empty && "cannot ignore non-empty functions in current mode"); IsIgnored = true; return; } clearDisasmState(); // Clear CFG state too. if (hasCFG()) { releaseCFG(); for (BinaryBasicBlock *BB : BasicBlocks) delete BB; clearList(BasicBlocks); for (BinaryBasicBlock *BB : DeletedBasicBlocks) delete BB; clearList(DeletedBasicBlocks); Layout.clear(); } CurrentState = State::Empty; IsIgnored = true; IsSimple = false; LLVM_DEBUG(dbgs() << "Ignoring " << getPrintName() << '\n'); } void BinaryFunction::duplicateConstantIslands() { assert(Islands && "function expected to have constant islands"); for (BinaryBasicBlock *BB : getLayout().blocks()) { if (!BB->isCold()) continue; for (MCInst &Inst : *BB) { int OpNum = 0; for (MCOperand &Operand : Inst) { if (!Operand.isExpr()) { ++OpNum; continue; } const MCSymbol *Symbol = BC.MIB->getTargetSymbol(Inst, OpNum); // Check if this is an island symbol if (!Islands->Symbols.count(Symbol) && !Islands->ProxySymbols.count(Symbol)) continue; // Create cold symbol, if missing auto ISym = Islands->ColdSymbols.find(Symbol); MCSymbol *ColdSymbol; if (ISym != Islands->ColdSymbols.end()) { ColdSymbol = ISym->second; } else { ColdSymbol = BC.Ctx->getOrCreateSymbol(Symbol->getName() + ".cold"); Islands->ColdSymbols[Symbol] = ColdSymbol; // Check if this is a proxy island symbol and update owner proxy map if (Islands->ProxySymbols.count(Symbol)) { BinaryFunction *Owner = Islands->ProxySymbols[Symbol]; auto IProxiedSym = Owner->Islands->Proxies[this].find(Symbol); Owner->Islands->ColdProxies[this][IProxiedSym->second] = ColdSymbol; } } // Update instruction reference Operand = MCOperand::createExpr(BC.MIB->getTargetExprFor( Inst, MCSymbolRefExpr::create(ColdSymbol, MCSymbolRefExpr::VK_None, *BC.Ctx), *BC.Ctx, 0)); ++OpNum; } } } } #ifndef MAX_PATH #define MAX_PATH 255 #endif static std::string constructFilename(std::string Filename, std::string Annotation, std::string Suffix) { std::replace(Filename.begin(), Filename.end(), '/', '-'); if (!Annotation.empty()) Annotation.insert(0, "-"); if (Filename.size() + Annotation.size() + Suffix.size() > MAX_PATH) { assert(Suffix.size() + Annotation.size() <= MAX_PATH); Filename.resize(MAX_PATH - (Suffix.size() + Annotation.size())); } Filename += Annotation; Filename += Suffix; return Filename; } static std::string formatEscapes(const std::string &Str) { std::string Result; for (unsigned I = 0; I < Str.size(); ++I) { char C = Str[I]; switch (C) { case '\n': Result += " "; break; case '"': break; default: Result += C; break; } } return Result; } void BinaryFunction::dumpGraph(raw_ostream &OS) const { OS << "digraph \"" << getPrintName() << "\" {\n" << "node [fontname=courier, shape=box, style=filled, colorscheme=brbg9]\n"; uint64_t Offset = Address; for (BinaryBasicBlock *BB : BasicBlocks) { auto LayoutPos = find(Layout.blocks(), BB); unsigned LayoutIndex = LayoutPos - Layout.block_begin(); const char *ColdStr = BB->isCold() ? " (cold)" : ""; std::vector Attrs; // Bold box for entry points if (isEntryPoint(*BB)) Attrs.push_back("penwidth=2"); if (BLI && BLI->getLoopFor(BB)) { // Distinguish innermost loops const BinaryLoop *Loop = BLI->getLoopFor(BB); if (Loop->isInnermost()) Attrs.push_back("fillcolor=6"); else // some outer loop Attrs.push_back("fillcolor=4"); } else { // non-loopy code Attrs.push_back("fillcolor=5"); } ListSeparator LS; OS << "\"" << BB->getName() << "\" ["; for (StringRef Attr : Attrs) OS << LS << Attr; OS << "]\n"; OS << format("\"%s\" [label=\"%s%s\\n(C:%lu,O:%lu,I:%u,L:%u,CFI:%u)\\n", BB->getName().data(), BB->getName().data(), ColdStr, BB->getKnownExecutionCount(), BB->getOffset(), getIndex(BB), LayoutIndex, BB->getCFIState()); if (opts::DotToolTipCode) { std::string Str; raw_string_ostream CS(Str); Offset = BC.printInstructions(CS, BB->begin(), BB->end(), Offset, this, /* PrintMCInst = */ false, /* PrintMemData = */ false, /* PrintRelocations = */ false, /* Endl = */ R"(\\l)"); OS << formatEscapes(CS.str()) << '\n'; } OS << "\"]\n"; // analyzeBranch is just used to get the names of the branch // opcodes. const MCSymbol *TBB = nullptr; const MCSymbol *FBB = nullptr; MCInst *CondBranch = nullptr; MCInst *UncondBranch = nullptr; const bool Success = BB->analyzeBranch(TBB, FBB, CondBranch, UncondBranch); const MCInst *LastInstr = BB->getLastNonPseudoInstr(); const bool IsJumpTable = LastInstr && BC.MIB->getJumpTable(*LastInstr); auto BI = BB->branch_info_begin(); for (BinaryBasicBlock *Succ : BB->successors()) { std::string Branch; if (Success) { if (Succ == BB->getConditionalSuccessor(true)) { Branch = CondBranch ? std::string(BC.InstPrinter->getOpcodeName( CondBranch->getOpcode())) : "TB"; } else if (Succ == BB->getConditionalSuccessor(false)) { Branch = UncondBranch ? std::string(BC.InstPrinter->getOpcodeName( UncondBranch->getOpcode())) : "FB"; } else { Branch = "FT"; } } if (IsJumpTable) Branch = "JT"; OS << format("\"%s\" -> \"%s\" [label=\"%s", BB->getName().data(), Succ->getName().data(), Branch.c_str()); if (BB->getExecutionCount() != COUNT_NO_PROFILE && BI->MispredictedCount != BinaryBasicBlock::COUNT_INFERRED) { OS << "\\n(C:" << BI->Count << ",M:" << BI->MispredictedCount << ")"; } else if (ExecutionCount != COUNT_NO_PROFILE && BI->Count != BinaryBasicBlock::COUNT_NO_PROFILE) { OS << "\\n(IC:" << BI->Count << ")"; } OS << "\"]\n"; ++BI; } for (BinaryBasicBlock *LP : BB->landing_pads()) { OS << format("\"%s\" -> \"%s\" [constraint=false style=dashed]\n", BB->getName().data(), LP->getName().data()); } } OS << "}\n"; } void BinaryFunction::viewGraph() const { SmallString Filename; if (std::error_code EC = sys::fs::createTemporaryFile("bolt-cfg", "dot", Filename)) { BC.errs() << "BOLT-ERROR: " << EC.message() << ", unable to create " << " bolt-cfg-XXXXX.dot temporary file.\n"; return; } dumpGraphToFile(std::string(Filename)); if (DisplayGraph(Filename)) BC.errs() << "BOLT-ERROR: Can't display " << Filename << " with graphviz.\n"; if (std::error_code EC = sys::fs::remove(Filename)) { BC.errs() << "BOLT-WARNING: " << EC.message() << ", failed to remove " << Filename << "\n"; } } void BinaryFunction::dumpGraphForPass(std::string Annotation) const { if (!opts::shouldPrint(*this)) return; std::string Filename = constructFilename(getPrintName(), Annotation, ".dot"); if (opts::Verbosity >= 1) BC.outs() << "BOLT-INFO: dumping CFG to " << Filename << "\n"; dumpGraphToFile(Filename); } void BinaryFunction::dumpGraphToFile(std::string Filename) const { std::error_code EC; raw_fd_ostream of(Filename, EC, sys::fs::OF_None); if (EC) { if (opts::Verbosity >= 1) { BC.errs() << "BOLT-WARNING: " << EC.message() << ", unable to open " << Filename << " for output.\n"; } return; } dumpGraph(of); } bool BinaryFunction::validateCFG() const { // Skip the validation of CFG after it is finalized if (CurrentState == State::CFG_Finalized) return true; for (BinaryBasicBlock *BB : BasicBlocks) if (!BB->validateSuccessorInvariants()) return false; // Make sure all blocks in CFG are valid. auto validateBlock = [this](const BinaryBasicBlock *BB, StringRef Desc) { if (!BB->isValid()) { BC.errs() << "BOLT-ERROR: deleted " << Desc << " " << BB->getName() << " detected in:\n"; this->dump(); return false; } return true; }; for (const BinaryBasicBlock *BB : BasicBlocks) { if (!validateBlock(BB, "block")) return false; for (const BinaryBasicBlock *PredBB : BB->predecessors()) if (!validateBlock(PredBB, "predecessor")) return false; for (const BinaryBasicBlock *SuccBB : BB->successors()) if (!validateBlock(SuccBB, "successor")) return false; for (const BinaryBasicBlock *LP : BB->landing_pads()) if (!validateBlock(LP, "landing pad")) return false; for (const BinaryBasicBlock *Thrower : BB->throwers()) if (!validateBlock(Thrower, "thrower")) return false; } for (const BinaryBasicBlock *BB : BasicBlocks) { std::unordered_set BBLandingPads; for (const BinaryBasicBlock *LP : BB->landing_pads()) { if (BBLandingPads.count(LP)) { BC.errs() << "BOLT-ERROR: duplicate landing pad detected in" << BB->getName() << " in function " << *this << '\n'; return false; } BBLandingPads.insert(LP); } std::unordered_set BBThrowers; for (const BinaryBasicBlock *Thrower : BB->throwers()) { if (BBThrowers.count(Thrower)) { BC.errs() << "BOLT-ERROR: duplicate thrower detected in" << BB->getName() << " in function " << *this << '\n'; return false; } BBThrowers.insert(Thrower); } for (const BinaryBasicBlock *LPBlock : BB->landing_pads()) { if (!llvm::is_contained(LPBlock->throwers(), BB)) { BC.errs() << "BOLT-ERROR: inconsistent landing pad detected in " << *this << ": " << BB->getName() << " is in LandingPads but not in " << LPBlock->getName() << " Throwers\n"; return false; } } for (const BinaryBasicBlock *Thrower : BB->throwers()) { if (!llvm::is_contained(Thrower->landing_pads(), BB)) { BC.errs() << "BOLT-ERROR: inconsistent thrower detected in " << *this << ": " << BB->getName() << " is in Throwers list but not in " << Thrower->getName() << " LandingPads\n"; return false; } } } return true; } void BinaryFunction::fixBranches() { auto &MIB = BC.MIB; MCContext *Ctx = BC.Ctx.get(); for (BinaryBasicBlock *BB : BasicBlocks) { const MCSymbol *TBB = nullptr; const MCSymbol *FBB = nullptr; MCInst *CondBranch = nullptr; MCInst *UncondBranch = nullptr; if (!BB->analyzeBranch(TBB, FBB, CondBranch, UncondBranch)) continue; // We will create unconditional branch with correct destination if needed. if (UncondBranch) BB->eraseInstruction(BB->findInstruction(UncondBranch)); // Basic block that follows the current one in the final layout. const BinaryBasicBlock *const NextBB = Layout.getBasicBlockAfter(BB, /*IgnoreSplits=*/false); if (BB->succ_size() == 1) { // __builtin_unreachable() could create a conditional branch that // falls-through into the next function - hence the block will have only // one valid successor. Since behaviour is undefined - we replace // the conditional branch with an unconditional if required. if (CondBranch) BB->eraseInstruction(BB->findInstruction(CondBranch)); if (BB->getSuccessor() == NextBB) continue; BB->addBranchInstruction(BB->getSuccessor()); } else if (BB->succ_size() == 2) { assert(CondBranch && "conditional branch expected"); const BinaryBasicBlock *TSuccessor = BB->getConditionalSuccessor(true); const BinaryBasicBlock *FSuccessor = BB->getConditionalSuccessor(false); // Eliminate unnecessary conditional branch. if (TSuccessor == FSuccessor) { // FIXME: at the moment, we cannot safely remove static key branches. if (MIB->isDynamicBranch(*CondBranch)) { if (opts::Verbosity) { BC.outs() << "BOLT-INFO: unable to remove redundant dynamic branch in " << *this << '\n'; } continue; } BB->removeDuplicateConditionalSuccessor(CondBranch); if (TSuccessor != NextBB) BB->addBranchInstruction(TSuccessor); continue; } // Reverse branch condition and swap successors. auto swapSuccessors = [&]() { if (!MIB->isReversibleBranch(*CondBranch)) { if (opts::Verbosity) { BC.outs() << "BOLT-INFO: unable to swap successors in " << *this << '\n'; } return false; } std::swap(TSuccessor, FSuccessor); BB->swapConditionalSuccessors(); auto L = BC.scopeLock(); MIB->reverseBranchCondition(*CondBranch, TSuccessor->getLabel(), Ctx); return true; }; // Check whether the next block is a "taken" target and try to swap it // with a "fall-through" target. if (TSuccessor == NextBB && swapSuccessors()) continue; // Update conditional branch destination if needed. if (MIB->getTargetSymbol(*CondBranch) != TSuccessor->getLabel()) { auto L = BC.scopeLock(); MIB->replaceBranchTarget(*CondBranch, TSuccessor->getLabel(), Ctx); } // No need for the unconditional branch. if (FSuccessor == NextBB) continue; if (BC.isX86()) { // We are going to generate two branches. Check if their targets are in // the same fragment as this block. If only one target is in the same // fragment, make it the destination of the conditional branch. There // is a chance it will be a short branch which takes 4 bytes fewer than // a long conditional branch. For unconditional branch, the difference // is 3 bytes. if (BB->getFragmentNum() != TSuccessor->getFragmentNum() && BB->getFragmentNum() == FSuccessor->getFragmentNum()) swapSuccessors(); } BB->addBranchInstruction(FSuccessor); } // Cases where the number of successors is 0 (block ends with a // terminator) or more than 2 (switch table) don't require branch // instruction adjustments. } assert((!isSimple() || validateCFG()) && "Invalid CFG detected after fixing branches"); } void BinaryFunction::propagateGnuArgsSizeInfo( MCPlusBuilder::AllocatorIdTy AllocId) { assert(CurrentState == State::Disassembled && "unexpected function state"); if (!hasEHRanges() || !usesGnuArgsSize()) return; // The current value of DW_CFA_GNU_args_size affects all following // invoke instructions until the next CFI overrides it. // It is important to iterate basic blocks in the original order when // assigning the value. uint64_t CurrentGnuArgsSize = 0; for (BinaryBasicBlock *BB : BasicBlocks) { for (auto II = BB->begin(); II != BB->end();) { MCInst &Instr = *II; if (BC.MIB->isCFI(Instr)) { const MCCFIInstruction *CFI = getCFIFor(Instr); if (CFI->getOperation() == MCCFIInstruction::OpGnuArgsSize) { CurrentGnuArgsSize = CFI->getOffset(); // Delete DW_CFA_GNU_args_size instructions and only regenerate // during the final code emission. The information is embedded // inside call instructions. II = BB->erasePseudoInstruction(II); continue; } } else if (BC.MIB->isInvoke(Instr)) { // Add the value of GNU_args_size as an extra operand to invokes. BC.MIB->addGnuArgsSize(Instr, CurrentGnuArgsSize); } ++II; } } } void BinaryFunction::postProcessBranches() { if (!isSimple()) return; for (BinaryBasicBlock &BB : blocks()) { auto LastInstrRI = BB.getLastNonPseudo(); if (BB.succ_size() == 1) { if (LastInstrRI != BB.rend() && BC.MIB->isConditionalBranch(*LastInstrRI)) { // __builtin_unreachable() could create a conditional branch that // falls-through into the next function - hence the block will have only // one valid successor. Such behaviour is undefined and thus we remove // the conditional branch while leaving a valid successor. BB.eraseInstruction(std::prev(LastInstrRI.base())); LLVM_DEBUG(dbgs() << "BOLT-DEBUG: erasing conditional branch in " << BB.getName() << " in function " << *this << '\n'); } } else if (BB.succ_size() == 0) { // Ignore unreachable basic blocks. if (BB.pred_size() == 0 || BB.isLandingPad()) continue; // If it's the basic block that does not end up with a terminator - we // insert a return instruction unless it's a call instruction. if (LastInstrRI == BB.rend()) { LLVM_DEBUG( dbgs() << "BOLT-DEBUG: at least one instruction expected in BB " << BB.getName() << " in function " << *this << '\n'); continue; } if (!BC.MIB->isTerminator(*LastInstrRI) && !BC.MIB->isCall(*LastInstrRI)) { LLVM_DEBUG(dbgs() << "BOLT-DEBUG: adding return to basic block " << BB.getName() << " in function " << *this << '\n'); MCInst ReturnInstr; BC.MIB->createReturn(ReturnInstr); BB.addInstruction(ReturnInstr); } } } assert(validateCFG() && "invalid CFG"); } MCSymbol *BinaryFunction::addEntryPointAtOffset(uint64_t Offset) { assert(Offset && "cannot add primary entry point"); assert(CurrentState == State::Empty || CurrentState == State::Disassembled); const uint64_t EntryPointAddress = getAddress() + Offset; MCSymbol *LocalSymbol = getOrCreateLocalLabel(EntryPointAddress); MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(LocalSymbol); if (EntrySymbol) return EntrySymbol; if (BinaryData *EntryBD = BC.getBinaryDataAtAddress(EntryPointAddress)) { EntrySymbol = EntryBD->getSymbol(); } else { EntrySymbol = BC.getOrCreateGlobalSymbol( EntryPointAddress, Twine("__ENTRY_") + getOneName() + "@"); } SecondaryEntryPoints[LocalSymbol] = EntrySymbol; BC.setSymbolToFunctionMap(EntrySymbol, this); return EntrySymbol; } MCSymbol *BinaryFunction::addEntryPoint(const BinaryBasicBlock &BB) { assert(CurrentState == State::CFG && "basic block can be added as an entry only in a function with CFG"); if (&BB == BasicBlocks.front()) return getSymbol(); MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(BB); if (EntrySymbol) return EntrySymbol; EntrySymbol = BC.Ctx->getOrCreateSymbol("__ENTRY_" + BB.getLabel()->getName()); SecondaryEntryPoints[BB.getLabel()] = EntrySymbol; BC.setSymbolToFunctionMap(EntrySymbol, this); return EntrySymbol; } MCSymbol *BinaryFunction::getSymbolForEntryID(uint64_t EntryID) { if (EntryID == 0) return getSymbol(); if (!isMultiEntry()) return nullptr; uint64_t NumEntries = 1; if (hasCFG()) { for (BinaryBasicBlock *BB : BasicBlocks) { MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(*BB); if (!EntrySymbol) continue; if (NumEntries == EntryID) return EntrySymbol; ++NumEntries; } } else { for (std::pair &KV : Labels) { MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(KV.second); if (!EntrySymbol) continue; if (NumEntries == EntryID) return EntrySymbol; ++NumEntries; } } return nullptr; } uint64_t BinaryFunction::getEntryIDForSymbol(const MCSymbol *Symbol) const { if (!isMultiEntry()) return 0; for (const MCSymbol *FunctionSymbol : getSymbols()) if (FunctionSymbol == Symbol) return 0; // Check all secondary entries available as either basic blocks or lables. uint64_t NumEntries = 1; for (const BinaryBasicBlock *BB : BasicBlocks) { MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(*BB); if (!EntrySymbol) continue; if (EntrySymbol == Symbol) return NumEntries; ++NumEntries; } NumEntries = 1; for (const std::pair &KV : Labels) { MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(KV.second); if (!EntrySymbol) continue; if (EntrySymbol == Symbol) return NumEntries; ++NumEntries; } llvm_unreachable("symbol not found"); } bool BinaryFunction::forEachEntryPoint(EntryPointCallbackTy Callback) const { bool Status = Callback(0, getSymbol()); if (!isMultiEntry()) return Status; for (const std::pair &KV : Labels) { if (!Status) break; MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(KV.second); if (!EntrySymbol) continue; Status = Callback(KV.first, EntrySymbol); } return Status; } BinaryFunction::BasicBlockListType BinaryFunction::dfs() const { BasicBlockListType DFS; std::stack Stack; std::set Visited; // Push entry points to the stack in reverse order. // // NB: we rely on the original order of entries to match. SmallVector EntryPoints; llvm::copy_if(BasicBlocks, std::back_inserter(EntryPoints), [&](const BinaryBasicBlock *const BB) { return isEntryPoint(*BB); }); // Sort entry points by their offset to make sure we got them in the right // order. llvm::stable_sort(EntryPoints, [](const BinaryBasicBlock *const A, const BinaryBasicBlock *const B) { return A->getOffset() < B->getOffset(); }); for (BinaryBasicBlock *const BB : reverse(EntryPoints)) Stack.push(BB); while (!Stack.empty()) { BinaryBasicBlock *BB = Stack.top(); Stack.pop(); if (!Visited.insert(BB).second) continue; DFS.push_back(BB); for (BinaryBasicBlock *SuccBB : BB->landing_pads()) { Stack.push(SuccBB); } const MCSymbol *TBB = nullptr; const MCSymbol *FBB = nullptr; MCInst *CondBranch = nullptr; MCInst *UncondBranch = nullptr; if (BB->analyzeBranch(TBB, FBB, CondBranch, UncondBranch) && CondBranch && BB->succ_size() == 2) { if (BC.MIB->getCanonicalBranchCondCode(BC.MIB->getCondCode( *CondBranch)) == BC.MIB->getCondCode(*CondBranch)) { Stack.push(BB->getConditionalSuccessor(true)); Stack.push(BB->getConditionalSuccessor(false)); } else { Stack.push(BB->getConditionalSuccessor(false)); Stack.push(BB->getConditionalSuccessor(true)); } } else { for (BinaryBasicBlock *SuccBB : BB->successors()) { Stack.push(SuccBB); } } } return DFS; } size_t BinaryFunction::computeHash(bool UseDFS, HashFunction HashFunction, OperandHashFuncTy OperandHashFunc) const { LLVM_DEBUG({ dbgs() << "BOLT-DEBUG: computeHash " << getPrintName() << ' ' << (UseDFS ? "dfs" : "bin") << " order " << (HashFunction == HashFunction::StdHash ? "std::hash" : "xxh3") << '\n'; }); if (size() == 0) return 0; assert(hasCFG() && "function is expected to have CFG"); SmallVector Order; if (UseDFS) llvm::copy(dfs(), std::back_inserter(Order)); else llvm::copy(Layout.blocks(), std::back_inserter(Order)); // The hash is computed by creating a string of all instruction opcodes and // possibly their operands and then hashing that string with std::hash. std::string HashString; for (const BinaryBasicBlock *BB : Order) HashString.append(hashBlock(BC, *BB, OperandHashFunc)); switch (HashFunction) { case HashFunction::StdHash: return Hash = std::hash{}(HashString); case HashFunction::XXH3: return Hash = llvm::xxh3_64bits(HashString); } llvm_unreachable("Unhandled HashFunction"); } void BinaryFunction::insertBasicBlocks( BinaryBasicBlock *Start, std::vector> &&NewBBs, const bool UpdateLayout, const bool UpdateCFIState, const bool RecomputeLandingPads) { const int64_t StartIndex = Start ? getIndex(Start) : -1LL; const size_t NumNewBlocks = NewBBs.size(); BasicBlocks.insert(BasicBlocks.begin() + (StartIndex + 1), NumNewBlocks, nullptr); int64_t I = StartIndex + 1; for (std::unique_ptr &BB : NewBBs) { assert(!BasicBlocks[I]); BasicBlocks[I++] = BB.release(); } if (RecomputeLandingPads) recomputeLandingPads(); else updateBBIndices(0); if (UpdateLayout) updateLayout(Start, NumNewBlocks); if (UpdateCFIState) updateCFIState(Start, NumNewBlocks); } BinaryFunction::iterator BinaryFunction::insertBasicBlocks( BinaryFunction::iterator StartBB, std::vector> &&NewBBs, const bool UpdateLayout, const bool UpdateCFIState, const bool RecomputeLandingPads) { const unsigned StartIndex = getIndex(&*StartBB); const size_t NumNewBlocks = NewBBs.size(); BasicBlocks.insert(BasicBlocks.begin() + StartIndex + 1, NumNewBlocks, nullptr); auto RetIter = BasicBlocks.begin() + StartIndex + 1; unsigned I = StartIndex + 1; for (std::unique_ptr &BB : NewBBs) { assert(!BasicBlocks[I]); BasicBlocks[I++] = BB.release(); } if (RecomputeLandingPads) recomputeLandingPads(); else updateBBIndices(0); if (UpdateLayout) updateLayout(*std::prev(RetIter), NumNewBlocks); if (UpdateCFIState) updateCFIState(*std::prev(RetIter), NumNewBlocks); return RetIter; } void BinaryFunction::updateBBIndices(const unsigned StartIndex) { for (unsigned I = StartIndex; I < BasicBlocks.size(); ++I) BasicBlocks[I]->Index = I; } void BinaryFunction::updateCFIState(BinaryBasicBlock *Start, const unsigned NumNewBlocks) { const int32_t CFIState = Start->getCFIStateAtExit(); const unsigned StartIndex = getIndex(Start) + 1; for (unsigned I = 0; I < NumNewBlocks; ++I) BasicBlocks[StartIndex + I]->setCFIState(CFIState); } void BinaryFunction::updateLayout(BinaryBasicBlock *Start, const unsigned NumNewBlocks) { BasicBlockListType::iterator Begin; BasicBlockListType::iterator End; // If start not provided copy new blocks from the beginning of BasicBlocks if (!Start) { Begin = BasicBlocks.begin(); End = BasicBlocks.begin() + NumNewBlocks; } else { unsigned StartIndex = getIndex(Start); Begin = std::next(BasicBlocks.begin(), StartIndex + 1); End = std::next(BasicBlocks.begin(), StartIndex + NumNewBlocks + 1); } // Insert new blocks in the layout immediately after Start. Layout.insertBasicBlocks(Start, {Begin, End}); Layout.updateLayoutIndices(); } bool BinaryFunction::checkForAmbiguousJumpTables() { SmallSet JumpTables; for (BinaryBasicBlock *&BB : BasicBlocks) { for (MCInst &Inst : *BB) { if (!BC.MIB->isIndirectBranch(Inst)) continue; uint64_t JTAddress = BC.MIB->getJumpTable(Inst); if (!JTAddress) continue; // This address can be inside another jump table, but we only consider // it ambiguous when the same start address is used, not the same JT // object. if (!JumpTables.count(JTAddress)) { JumpTables.insert(JTAddress); continue; } return true; } } return false; } void BinaryFunction::disambiguateJumpTables( MCPlusBuilder::AllocatorIdTy AllocId) { assert((opts::JumpTables != JTS_BASIC && isSimple()) || !BC.HasRelocations); SmallPtrSet JumpTables; for (BinaryBasicBlock *&BB : BasicBlocks) { for (MCInst &Inst : *BB) { if (!BC.MIB->isIndirectBranch(Inst)) continue; JumpTable *JT = getJumpTable(Inst); if (!JT) continue; if (JumpTables.insert(JT).second) continue; // This instruction is an indirect jump using a jump table, but it is // using the same jump table of another jump. Try all our tricks to // extract the jump table symbol and make it point to a new, duplicated JT MCPhysReg BaseReg1; uint64_t Scale; const MCSymbol *Target; // In case we match if our first matcher, first instruction is the one to // patch MCInst *JTLoadInst = &Inst; // Try a standard indirect jump matcher, scale 8 std::unique_ptr IndJmpMatcher = BC.MIB->matchIndJmp(BC.MIB->matchReg(BaseReg1), BC.MIB->matchImm(Scale), BC.MIB->matchReg(), /*Offset=*/BC.MIB->matchSymbol(Target)); if (!IndJmpMatcher->match( *BC.MRI, *BC.MIB, MutableArrayRef(&*BB->begin(), &Inst + 1), -1) || BaseReg1 != BC.MIB->getNoRegister() || Scale != 8) { MCPhysReg BaseReg2; uint64_t Offset; // Standard JT matching failed. Trying now: // movq "jt.2397/1"(,%rax,8), %rax // jmpq *%rax std::unique_ptr LoadMatcherOwner = BC.MIB->matchLoad(BC.MIB->matchReg(BaseReg1), BC.MIB->matchImm(Scale), BC.MIB->matchReg(), /*Offset=*/BC.MIB->matchSymbol(Target)); MCPlusBuilder::MCInstMatcher *LoadMatcher = LoadMatcherOwner.get(); std::unique_ptr IndJmpMatcher2 = BC.MIB->matchIndJmp(std::move(LoadMatcherOwner)); if (!IndJmpMatcher2->match( *BC.MRI, *BC.MIB, MutableArrayRef(&*BB->begin(), &Inst + 1), -1) || BaseReg1 != BC.MIB->getNoRegister() || Scale != 8) { // JT matching failed. Trying now: // PIC-style matcher, scale 4 // addq %rdx, %rsi // addq %rdx, %rdi // leaq DATAat0x402450(%rip), %r11 // movslq (%r11,%rdx,4), %rcx // addq %r11, %rcx // jmpq *%rcx # JUMPTABLE @0x402450 std::unique_ptr PICIndJmpMatcher = BC.MIB->matchIndJmp(BC.MIB->matchAdd( BC.MIB->matchReg(BaseReg1), BC.MIB->matchLoad(BC.MIB->matchReg(BaseReg2), BC.MIB->matchImm(Scale), BC.MIB->matchReg(), BC.MIB->matchImm(Offset)))); std::unique_ptr LEAMatcherOwner = BC.MIB->matchLoadAddr(BC.MIB->matchSymbol(Target)); MCPlusBuilder::MCInstMatcher *LEAMatcher = LEAMatcherOwner.get(); std::unique_ptr PICBaseAddrMatcher = BC.MIB->matchIndJmp(BC.MIB->matchAdd(std::move(LEAMatcherOwner), BC.MIB->matchAnyOperand())); if (!PICIndJmpMatcher->match( *BC.MRI, *BC.MIB, MutableArrayRef(&*BB->begin(), &Inst + 1), -1) || Scale != 4 || BaseReg1 != BaseReg2 || Offset != 0 || !PICBaseAddrMatcher->match( *BC.MRI, *BC.MIB, MutableArrayRef(&*BB->begin(), &Inst + 1), -1)) { llvm_unreachable("Failed to extract jump table base"); continue; } // Matched PIC, identify the instruction with the reference to the JT JTLoadInst = LEAMatcher->CurInst; } else { // Matched non-PIC JTLoadInst = LoadMatcher->CurInst; } } uint64_t NewJumpTableID = 0; const MCSymbol *NewJTLabel; std::tie(NewJumpTableID, NewJTLabel) = BC.duplicateJumpTable(*this, JT, Target); { auto L = BC.scopeLock(); BC.MIB->replaceMemOperandDisp(*JTLoadInst, NewJTLabel, BC.Ctx.get()); } // We use a unique ID with the high bit set as address for this "injected" // jump table (not originally in the input binary). BC.MIB->setJumpTable(Inst, NewJumpTableID, 0, AllocId); } } } bool BinaryFunction::replaceJumpTableEntryIn(BinaryBasicBlock *BB, BinaryBasicBlock *OldDest, BinaryBasicBlock *NewDest) { MCInst *Instr = BB->getLastNonPseudoInstr(); if (!Instr || !BC.MIB->isIndirectBranch(*Instr)) return false; uint64_t JTAddress = BC.MIB->getJumpTable(*Instr); assert(JTAddress && "Invalid jump table address"); JumpTable *JT = getJumpTableContainingAddress(JTAddress); assert(JT && "No jump table structure for this indirect branch"); bool Patched = JT->replaceDestination(JTAddress, OldDest->getLabel(), NewDest->getLabel()); (void)Patched; assert(Patched && "Invalid entry to be replaced in jump table"); return true; } BinaryBasicBlock *BinaryFunction::splitEdge(BinaryBasicBlock *From, BinaryBasicBlock *To) { // Create intermediate BB MCSymbol *Tmp; { auto L = BC.scopeLock(); Tmp = BC.Ctx->createNamedTempSymbol("SplitEdge"); } // Link new BBs to the original input offset of the From BB, so we can map // samples recorded in new BBs back to the original BB seem in the input // binary (if using BAT) std::unique_ptr NewBB = createBasicBlock(Tmp); NewBB->setOffset(From->getInputOffset()); BinaryBasicBlock *NewBBPtr = NewBB.get(); // Update "From" BB auto I = From->succ_begin(); auto BI = From->branch_info_begin(); for (; I != From->succ_end(); ++I) { if (*I == To) break; ++BI; } assert(I != From->succ_end() && "Invalid CFG edge in splitEdge!"); uint64_t OrigCount = BI->Count; uint64_t OrigMispreds = BI->MispredictedCount; replaceJumpTableEntryIn(From, To, NewBBPtr); From->replaceSuccessor(To, NewBBPtr, OrigCount, OrigMispreds); NewBB->addSuccessor(To, OrigCount, OrigMispreds); NewBB->setExecutionCount(OrigCount); NewBB->setIsCold(From->isCold()); // Update CFI and BB layout with new intermediate BB std::vector> NewBBs; NewBBs.emplace_back(std::move(NewBB)); insertBasicBlocks(From, std::move(NewBBs), true, true, /*RecomputeLandingPads=*/false); return NewBBPtr; } void BinaryFunction::deleteConservativeEdges() { // Our goal is to aggressively remove edges from the CFG that we believe are // wrong. This is used for instrumentation, where it is safe to remove // fallthrough edges because we won't reorder blocks. for (auto I = BasicBlocks.begin(), E = BasicBlocks.end(); I != E; ++I) { BinaryBasicBlock *BB = *I; if (BB->succ_size() != 1 || BB->size() == 0) continue; auto NextBB = std::next(I); MCInst *Last = BB->getLastNonPseudoInstr(); // Fallthrough is a landing pad? Delete this edge (as long as we don't // have a direct jump to it) if ((*BB->succ_begin())->isLandingPad() && NextBB != E && *BB->succ_begin() == *NextBB && Last && !BC.MIB->isBranch(*Last)) { BB->removeAllSuccessors(); continue; } // Look for suspicious calls at the end of BB where gcc may optimize it and // remove the jump to the epilogue when it knows the call won't return. if (!Last || !BC.MIB->isCall(*Last)) continue; const MCSymbol *CalleeSymbol = BC.MIB->getTargetSymbol(*Last); if (!CalleeSymbol) continue; StringRef CalleeName = CalleeSymbol->getName(); if (CalleeName != "__cxa_throw@PLT" && CalleeName != "_Unwind_Resume@PLT" && CalleeName != "__cxa_rethrow@PLT" && CalleeName != "exit@PLT" && CalleeName != "abort@PLT") continue; BB->removeAllSuccessors(); } } bool BinaryFunction::isSymbolValidInScope(const SymbolRef &Symbol, uint64_t SymbolSize) const { // If this symbol is in a different section from the one where the // function symbol is, don't consider it as valid. if (!getOriginSection()->containsAddress( cantFail(Symbol.getAddress(), "cannot get symbol address"))) return false; // Some symbols are tolerated inside function bodies, others are not. // The real function boundaries may not be known at this point. if (BC.isMarker(Symbol)) return true; // It's okay to have a zero-sized symbol in the middle of non-zero-sized // function. if (SymbolSize == 0 && containsAddress(cantFail(Symbol.getAddress()))) return true; if (cantFail(Symbol.getType()) != SymbolRef::ST_Unknown) return false; if (cantFail(Symbol.getFlags()) & SymbolRef::SF_Global) return false; return true; } void BinaryFunction::adjustExecutionCount(uint64_t Count) { if (getKnownExecutionCount() == 0 || Count == 0) return; if (ExecutionCount < Count) Count = ExecutionCount; double AdjustmentRatio = ((double)ExecutionCount - Count) / ExecutionCount; if (AdjustmentRatio < 0.0) AdjustmentRatio = 0.0; for (BinaryBasicBlock &BB : blocks()) BB.adjustExecutionCount(AdjustmentRatio); ExecutionCount -= Count; } BinaryFunction::~BinaryFunction() { for (BinaryBasicBlock *BB : BasicBlocks) delete BB; for (BinaryBasicBlock *BB : DeletedBasicBlocks) delete BB; } void BinaryFunction::constructDomTree() { BDT.reset(new BinaryDominatorTree); BDT->recalculate(*this); } void BinaryFunction::calculateLoopInfo() { if (!hasDomTree()) constructDomTree(); // Discover loops. BLI.reset(new BinaryLoopInfo()); BLI->analyze(getDomTree()); // Traverse discovered loops and add depth and profile information. std::stack St; for (auto I = BLI->begin(), E = BLI->end(); I != E; ++I) { St.push(*I); ++BLI->OuterLoops; } while (!St.empty()) { BinaryLoop *L = St.top(); St.pop(); ++BLI->TotalLoops; BLI->MaximumDepth = std::max(L->getLoopDepth(), BLI->MaximumDepth); // Add nested loops in the stack. for (BinaryLoop::iterator I = L->begin(), E = L->end(); I != E; ++I) St.push(*I); // Skip if no valid profile is found. if (!hasValidProfile()) { L->EntryCount = COUNT_NO_PROFILE; L->ExitCount = COUNT_NO_PROFILE; L->TotalBackEdgeCount = COUNT_NO_PROFILE; continue; } // Compute back edge count. SmallVector Latches; L->getLoopLatches(Latches); for (BinaryBasicBlock *Latch : Latches) { auto BI = Latch->branch_info_begin(); for (BinaryBasicBlock *Succ : Latch->successors()) { if (Succ == L->getHeader()) { assert(BI->Count != BinaryBasicBlock::COUNT_NO_PROFILE && "profile data not found"); L->TotalBackEdgeCount += BI->Count; } ++BI; } } // Compute entry count. L->EntryCount = L->getHeader()->getExecutionCount() - L->TotalBackEdgeCount; // Compute exit count. SmallVector ExitEdges; L->getExitEdges(ExitEdges); for (BinaryLoop::Edge &Exit : ExitEdges) { const BinaryBasicBlock *Exiting = Exit.first; const BinaryBasicBlock *ExitTarget = Exit.second; auto BI = Exiting->branch_info_begin(); for (BinaryBasicBlock *Succ : Exiting->successors()) { if (Succ == ExitTarget) { assert(BI->Count != BinaryBasicBlock::COUNT_NO_PROFILE && "profile data not found"); L->ExitCount += BI->Count; } ++BI; } } } } void BinaryFunction::updateOutputValues(const BOLTLinker &Linker) { if (!isEmitted()) { assert(!isInjected() && "injected function should be emitted"); setOutputAddress(getAddress()); setOutputSize(getSize()); return; } const auto SymbolInfo = Linker.lookupSymbolInfo(getSymbol()->getName()); assert(SymbolInfo && "Cannot find function entry symbol"); setOutputAddress(SymbolInfo->Address); setOutputSize(SymbolInfo->Size); if (BC.HasRelocations || isInjected()) { if (hasConstantIsland()) { const auto DataAddress = Linker.lookupSymbol(getFunctionConstantIslandLabel()->getName()); assert(DataAddress && "Cannot find function CI symbol"); setOutputDataAddress(*DataAddress); for (auto It : Islands->Offsets) { const uint64_t OldOffset = It.first; BinaryData *BD = BC.getBinaryDataAtAddress(getAddress() + OldOffset); if (!BD) continue; MCSymbol *Symbol = It.second; const auto NewAddress = Linker.lookupSymbol(Symbol->getName()); assert(NewAddress && "Cannot find CI symbol"); auto &Section = *getCodeSection(); const auto NewOffset = *NewAddress - Section.getOutputAddress(); BD->setOutputLocation(Section, NewOffset); } } if (isSplit()) { for (FunctionFragment &FF : getLayout().getSplitFragments()) { ErrorOr ColdSection = getCodeSection(FF.getFragmentNum()); // If fragment is empty, cold section might not exist if (FF.empty() && ColdSection.getError()) continue; const MCSymbol *ColdStartSymbol = getSymbol(FF.getFragmentNum()); // If fragment is empty, symbol might have not been emitted if (FF.empty() && (!ColdStartSymbol || !ColdStartSymbol->isDefined()) && !hasConstantIsland()) continue; assert(ColdStartSymbol && ColdStartSymbol->isDefined() && "split function should have defined cold symbol"); const auto ColdStartSymbolInfo = Linker.lookupSymbolInfo(ColdStartSymbol->getName()); assert(ColdStartSymbolInfo && "Cannot find cold start symbol"); FF.setAddress(ColdStartSymbolInfo->Address); FF.setImageSize(ColdStartSymbolInfo->Size); if (hasConstantIsland()) { const auto DataAddress = Linker.lookupSymbol( getFunctionColdConstantIslandLabel()->getName()); assert(DataAddress && "Cannot find cold CI symbol"); setOutputColdDataAddress(*DataAddress); } } } } // Update basic block output ranges for the debug info, if we have // secondary entry points in the symbol table to update or if writing BAT. if (!requiresAddressMap()) return; // AArch64 may have functions that only contains a constant island (no code). if (getLayout().block_empty()) return; for (FunctionFragment &FF : getLayout().fragments()) { if (FF.empty()) continue; const uint64_t FragmentBaseAddress = getCodeSection(isSimple() ? FF.getFragmentNum() : FragmentNum::main()) ->getOutputAddress(); BinaryBasicBlock *PrevBB = nullptr; for (BinaryBasicBlock *const BB : FF) { assert(BB->getLabel()->isDefined() && "symbol should be defined"); if (!BC.HasRelocations) { if (BB->isSplit()) assert(FragmentBaseAddress == FF.getAddress()); else assert(FragmentBaseAddress == getOutputAddress()); (void)FragmentBaseAddress; } // Injected functions likely will fail lookup, as they have no // input range. Just assign the BB the output address of the // function. auto MaybeBBAddress = BC.getIOAddressMap().lookup(BB->getLabel()); const uint64_t BBAddress = MaybeBBAddress ? *MaybeBBAddress : BB->isSplit() ? FF.getAddress() : getOutputAddress(); BB->setOutputStartAddress(BBAddress); if (PrevBB) { assert(PrevBB->getOutputAddressRange().first <= BBAddress && "Bad output address for basic block."); assert((PrevBB->getOutputAddressRange().first != BBAddress || !hasInstructions() || !PrevBB->getNumNonPseudos()) && "Bad output address for basic block."); PrevBB->setOutputEndAddress(BBAddress); } PrevBB = BB; } PrevBB->setOutputEndAddress(PrevBB->isSplit() ? FF.getAddress() + FF.getImageSize() : getOutputAddress() + getOutputSize()); } // Reset output addresses for deleted blocks. for (BinaryBasicBlock *BB : DeletedBasicBlocks) { BB->setOutputStartAddress(0); BB->setOutputEndAddress(0); } } DebugAddressRangesVector BinaryFunction::getOutputAddressRanges() const { DebugAddressRangesVector OutputRanges; if (isFolded()) return OutputRanges; if (IsFragment) return OutputRanges; OutputRanges.emplace_back(getOutputAddress(), getOutputAddress() + getOutputSize()); if (isSplit()) { assert(isEmitted() && "split function should be emitted"); for (const FunctionFragment &FF : getLayout().getSplitFragments()) OutputRanges.emplace_back(FF.getAddress(), FF.getAddress() + FF.getImageSize()); } if (isSimple()) return OutputRanges; for (BinaryFunction *Frag : Fragments) { assert(!Frag->isSimple() && "fragment of non-simple function should also be non-simple"); OutputRanges.emplace_back(Frag->getOutputAddress(), Frag->getOutputAddress() + Frag->getOutputSize()); } return OutputRanges; } uint64_t BinaryFunction::translateInputToOutputAddress(uint64_t Address) const { if (isFolded()) return 0; // If the function hasn't changed return the same address. if (!isEmitted()) return Address; if (Address < getAddress()) return 0; // Check if the address is associated with an instruction that is tracked // by address translation. if (auto OutputAddress = BC.getIOAddressMap().lookup(Address)) return *OutputAddress; // FIXME: #18950828 - we rely on relative offsets inside basic blocks to stay // intact. Instead we can use pseudo instructions and/or annotations. const uint64_t Offset = Address - getAddress(); const BinaryBasicBlock *BB = getBasicBlockContainingOffset(Offset); if (!BB) { // Special case for address immediately past the end of the function. if (Offset == getSize()) return getOutputAddress() + getOutputSize(); return 0; } return std::min(BB->getOutputAddressRange().first + Offset - BB->getOffset(), BB->getOutputAddressRange().second); } DebugAddressRangesVector BinaryFunction::translateInputToOutputRange(DebugAddressRange InRange) const { DebugAddressRangesVector OutRanges; // The function was removed from the output. Return an empty range. if (isFolded()) return OutRanges; // If the function hasn't changed return the same range. if (!isEmitted()) { OutRanges.emplace_back(InRange); return OutRanges; } if (!containsAddress(InRange.LowPC)) return OutRanges; // Special case of an empty range [X, X). Some tools expect X to be updated. if (InRange.LowPC == InRange.HighPC) { if (uint64_t NewPC = translateInputToOutputAddress(InRange.LowPC)) OutRanges.push_back(DebugAddressRange{NewPC, NewPC}); return OutRanges; } uint64_t InputOffset = InRange.LowPC - getAddress(); const uint64_t InputEndOffset = std::min(InRange.HighPC - getAddress(), getSize()); auto BBI = llvm::upper_bound(BasicBlockOffsets, BasicBlockOffset(InputOffset, nullptr), CompareBasicBlockOffsets()); assert(BBI != BasicBlockOffsets.begin()); // Iterate over blocks in the input order using BasicBlockOffsets. for (--BBI; InputOffset < InputEndOffset && BBI != BasicBlockOffsets.end(); InputOffset = BBI->second->getEndOffset(), ++BBI) { const BinaryBasicBlock &BB = *BBI->second; if (InputOffset < BB.getOffset() || InputOffset >= BB.getEndOffset()) { LLVM_DEBUG( dbgs() << "BOLT-DEBUG: invalid debug address range detected for " << *this << " : [0x" << Twine::utohexstr(InRange.LowPC) << ", 0x" << Twine::utohexstr(InRange.HighPC) << "]\n"); break; } // Skip the block if it wasn't emitted. if (!BB.getOutputAddressRange().first) continue; // Find output address for an instruction with an offset greater or equal // to /p Offset. The output address should fall within the same basic // block boundaries. auto translateBlockOffset = [&](const uint64_t Offset) { const uint64_t OutAddress = BB.getOutputAddressRange().first + Offset; return std::min(OutAddress, BB.getOutputAddressRange().second); }; uint64_t OutLowPC = BB.getOutputAddressRange().first; if (InputOffset > BB.getOffset()) OutLowPC = translateBlockOffset(InputOffset - BB.getOffset()); uint64_t OutHighPC = BB.getOutputAddressRange().second; if (InputEndOffset < BB.getEndOffset()) { assert(InputEndOffset >= BB.getOffset()); OutHighPC = translateBlockOffset(InputEndOffset - BB.getOffset()); } // Check if we can expand the last translated range. if (!OutRanges.empty() && OutRanges.back().HighPC == OutLowPC) OutRanges.back().HighPC = std::max(OutRanges.back().HighPC, OutHighPC); else OutRanges.emplace_back(OutLowPC, std::max(OutLowPC, OutHighPC)); } LLVM_DEBUG({ dbgs() << "BOLT-DEBUG: translated address range " << InRange << " -> "; for (const DebugAddressRange &R : OutRanges) dbgs() << R << ' '; dbgs() << '\n'; }); return OutRanges; } MCInst *BinaryFunction::getInstructionAtOffset(uint64_t Offset) { if (CurrentState == State::Disassembled) { auto II = Instructions.find(Offset); return (II == Instructions.end()) ? nullptr : &II->second; } else if (CurrentState == State::CFG) { BinaryBasicBlock *BB = getBasicBlockContainingOffset(Offset); if (!BB) return nullptr; for (MCInst &Inst : *BB) { constexpr uint32_t InvalidOffset = std::numeric_limits::max(); if (Offset == BC.MIB->getOffsetWithDefault(Inst, InvalidOffset)) return &Inst; } if (MCInst *LastInstr = BB->getLastNonPseudoInstr()) { if (std::optional Size = BC.MIB->getSize(*LastInstr)) { if (BB->getEndOffset() - Offset == Size) { return LastInstr; } } } return nullptr; } else { llvm_unreachable("invalid CFG state to use getInstructionAtOffset()"); } } MCInst *BinaryFunction::getInstructionContainingOffset(uint64_t Offset) { assert(CurrentState == State::Disassembled && "Wrong function state"); if (Offset > Size) return nullptr; auto II = Instructions.upper_bound(Offset); assert(II != Instructions.begin() && "First instruction not at offset 0"); --II; return &II->second; } void BinaryFunction::printLoopInfo(raw_ostream &OS) const { if (!opts::shouldPrint(*this)) return; OS << "Loop Info for Function \"" << *this << "\""; if (hasValidProfile()) OS << " (count: " << getExecutionCount() << ")"; OS << "\n"; std::stack St; for (BinaryLoop *L : *BLI) St.push(L); while (!St.empty()) { BinaryLoop *L = St.top(); St.pop(); for (BinaryLoop *Inner : *L) St.push(Inner); if (!hasValidProfile()) continue; OS << (L->getLoopDepth() > 1 ? "Nested" : "Outer") << " loop header: " << L->getHeader()->getName(); OS << "\n"; OS << "Loop basic blocks: "; ListSeparator LS; for (BinaryBasicBlock *BB : L->blocks()) OS << LS << BB->getName(); OS << "\n"; if (hasValidProfile()) { OS << "Total back edge count: " << L->TotalBackEdgeCount << "\n"; OS << "Loop entry count: " << L->EntryCount << "\n"; OS << "Loop exit count: " << L->ExitCount << "\n"; if (L->EntryCount > 0) { OS << "Average iters per entry: " << format("%.4lf", (double)L->TotalBackEdgeCount / L->EntryCount) << "\n"; } } OS << "----\n"; } OS << "Total number of loops: " << BLI->TotalLoops << "\n"; OS << "Number of outer loops: " << BLI->OuterLoops << "\n"; OS << "Maximum nested loop depth: " << BLI->MaximumDepth << "\n\n"; } bool BinaryFunction::isAArch64Veneer() const { if (empty() || hasIslandsInfo()) return false; BinaryBasicBlock &BB = **BasicBlocks.begin(); for (MCInst &Inst : BB) if (!BC.MIB->hasAnnotation(Inst, "AArch64Veneer")) return false; for (auto I = BasicBlocks.begin() + 1, E = BasicBlocks.end(); I != E; ++I) { for (MCInst &Inst : **I) if (!BC.MIB->isNoop(Inst)) return false; } return true; } void BinaryFunction::addRelocation(uint64_t Address, MCSymbol *Symbol, uint64_t RelType, uint64_t Addend, uint64_t Value) { assert(Address >= getAddress() && Address < getAddress() + getMaxSize() && "address is outside of the function"); uint64_t Offset = Address - getAddress(); LLVM_DEBUG(dbgs() << "BOLT-DEBUG: addRelocation in " << formatv("{0}@{1:x} against {2}\n", *this, Offset, (Symbol ? Symbol->getName() : ""))); bool IsCI = BC.isAArch64() && isInConstantIsland(Address); std::map &Rels = IsCI ? Islands->Relocations : Relocations; if (BC.MIB->shouldRecordCodeRelocation(RelType)) Rels[Offset] = Relocation{Offset, Symbol, RelType, Addend, Value}; } } // namespace bolt } // namespace llvm