//===--- BinaryFunction.cpp - Interface for machine-level function --------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // //===----------------------------------------------------------------------===// #include "BinaryBasicBlock.h" #include "BinaryFunction.h" #include "DataReader.h" #include "DynoStats.h" #include "MCPlusBuilder.h" #include "llvm/ADT/edit_distance.h" #include "llvm/ADT/SmallSet.h" #include "llvm/ADT/StringRef.h" #include "llvm/DebugInfo/DWARF/DWARFContext.h" #include "llvm/MC/MCAsmInfo.h" #include "llvm/MC/MCAsmLayout.h" #include "llvm/MC/MCContext.h" #include "llvm/MC/MCExpr.h" #include "llvm/MC/MCInst.h" #include "llvm/MC/MCInstPrinter.h" #include "llvm/MC/MCSection.h" #include "llvm/MC/MCSectionELF.h" #include "llvm/MC/MCStreamer.h" #include "llvm/Object/ObjectFile.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/GraphWriter.h" #include "llvm/Support/Timer.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Support/Regex.h" #include #include #include #include #include #include #undef DEBUG_TYPE #define DEBUG_TYPE "bolt" using namespace llvm; using namespace bolt; namespace opts { extern cl::OptionCategory BoltCategory; extern cl::OptionCategory BoltOptCategory; extern cl::OptionCategory BoltRelocCategory; extern cl::opt EnableBAT; extern cl::opt Instrument; extern cl::opt StrictMode; extern cl::opt UpdateDebugSections; extern cl::opt Verbosity; 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::init(false), cl::ZeroOrMore, cl::Hidden, cl::cat(BoltCategory)); static cl::opt DotToolTipCode("dot-tooltip-code", cl::desc("add basic block instructions as tool tips on nodes"), cl::ZeroOrMore, 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)); cl::opt PreserveBlocksAlignment("preserve-blocks-alignment", cl::desc("try to preserve basic block alignment"), cl::init(false), cl::ZeroOrMore, 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::ZeroOrMore, 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 (on by default)"), cl::init(true), cl::ZeroOrMore, cl::Hidden, cl::cat(BoltCategory)); bool shouldPrint(const BinaryFunction &Function) { if (Function.isIgnored()) return false; if (PrintOnly.empty()) return true; for (auto &Name : opts::PrintOnly) { if (Function.hasNameRegex(Name)) { return true; } } return false; } } // namespace opts namespace llvm { namespace bolt { constexpr unsigned BinaryFunction::MinAlign; namespace { template 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. SMLoc findDebugLineInformationForInstructionAt( uint64_t Address, DWARFUnitLineTable &ULT) { // 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. assert( sizeof(decltype(SMLoc().getPointer())) >= sizeof(DebugLineTableRowRef) && "Cannot fit instruction debug line information into SMLoc's pointer"); SMLoc NullResult = DebugLineTableRowRef::NULL_ROW.toSMLoc(); auto &LineTable = ULT.second; if (!LineTable) return NullResult; uint32_t RowIndex = LineTable->lookupAddress(Address); 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 = ULT.first->getOffset(); InstructionLocation->RowIndex = RowIndex + 1; return SMLoc::getFromPointer(Ptr); } } // namespace uint64_t BinaryFunction::Count = 0; Optional BinaryFunction::hasNameRegex(const StringRef Name) const { const auto RegexName = (Twine("^") + StringRef(Name) + "$").str(); Regex MatchName(RegexName); auto Match = forEachName([&MatchName](StringRef Name) { return MatchName.match(Name); }); return Match; } std::string BinaryFunction::getDemangledName() const { StringRef MangledName = getOneName(); MangledName = MangledName.substr(0, MangledName.find_first_of('/')); int Status = 0; char *const Name = abi::__cxa_demangle(MangledName.str().c_str(), 0, 0, &Status); const std::string NameStr(Status == 0 ? Name : MangledName); ::free(Name); return NameStr; } 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 = std::upper_bound(BasicBlockOffsets.begin(), BasicBlockOffsets.end(), BasicBlockOffset(Offset, nullptr), CompareBasicBlockOffsets()); assert(I != BasicBlockOffsets.begin() && "first basic block not at offset 0"); --I; auto *BB = I->second; return (Offset < BB->getOffset() + BB->getOriginalSize()) ? BB : nullptr; } void BinaryFunction::markUnreachableBlocks() { std::stack Stack; for (auto *BB : layout()) { BB->markValid(false); } // Add all entries and landing pads as roots. for (auto *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 (T29418024 / GH-issue20) for (const auto &Inst : *BB) { if (BC.MIB->getJumpTable(Inst)) { Stack.push(BB); BB->markValid(true); break; } } } // Determine reachable BBs from the entry point while (!Stack.empty()) { auto BB = Stack.top(); Stack.pop(); for (auto 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() { BasicBlockOrderType NewLayout; unsigned Count = 0; uint64_t Bytes = 0; for (auto *BB : layout()) { if (BB->isValid()) { NewLayout.push_back(BB); } else { assert(!isEntryPoint(*BB) && "all entry blocks must be valid"); ++Count; Bytes += BC.computeCodeSize(BB->begin(), BB->end()); } } BasicBlocksLayout = std::move(NewLayout); BasicBlockListType NewBasicBlocks; for (auto I = BasicBlocks.begin(), E = BasicBlocks.end(); I != E; ++I) { auto *BB = *I; if (BB->isValid()) { NewBasicBlocks.push_back(BB); } else { // Make sure the block is removed from the list of predecessors. BB->removeAllSuccessors(); DeletedBasicBlocks.push_back(BB); } } BasicBlocks = std::move(NewBasicBlocks); assert(BasicBlocks.size() == BasicBlocksLayout.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 auto *CalleeBF = BC.getFunctionForSymbol(CalleeSymbol); if (CalleeBF) { if(CalleeBF->isInjected()) return true; if (hasValidIndex() && CalleeBF->hasValidIndex()) { return getIndex() < CalleeBF->getIndex(); } else if (hasValidIndex() && !CalleeBF->hasValidIndex()) { return true; } else if (!hasValidIndex() && CalleeBF->hasValidIndex()) { return false; } else { return getAddress() < CalleeBF->getAddress(); } } else { // Absolute symbol. auto CalleeAddressOrError = BC.getSymbolValue(*CalleeSymbol); assert(CalleeAddressOrError && "unregistered symbol found"); return *CalleeAddressOrError > getAddress(); } } void BinaryFunction::dump(bool PrintInstructions) const { print(dbgs(), "", PrintInstructions); } void BinaryFunction::print(raw_ostream &OS, std::string Annotation, bool PrintInstructions) const { if (!opts::shouldPrint(*this)) return; StringRef SectionName = IsInjected ? "" : InputSection->getName(); OS << "Binary Function \"" << *this << "\" " << Annotation << " {"; auto AllNames = getNames(); if (AllNames.size() > 1) { OS << "\n All names : "; auto Sep = ""; for (const auto Name : AllNames) { OS << Sep << Name; Sep = "\n "; } } OS << "\n Number : " << FunctionNumber << "\n State : " << CurrentState << "\n Address : 0x" << Twine::utohexstr(Address) << "\n Size : 0x" << Twine::utohexstr(Size) << "\n MaxSize : 0x" << Twine::utohexstr(MaxSize) << "\n Offset : 0x" << Twine::utohexstr(FileOffset) << "\n Section : " << SectionName << "\n Orc Section : " << getCodeSectionName() << "\n LSDA : 0x" << Twine::utohexstr(getLSDAAddress()) << "\n IsSimple : " << IsSimple << "\n IsMultiEntry: " << isMultiEntry() << "\n IsSplit : " << isSplit() << "\n BB Count : " << size(); if (HasFixedIndirectBranch) { OS << "\n HasFixedIndirectBranch : true"; } if (HasUnknownControlFlow) { OS << "\n Unknown CF : true"; } if (IsFragment) { OS << "\n IsFragment : true"; } if (isFolded()) { OS << "\n FoldedInto : " << *getFoldedIntoFunction(); } if (ParentFunction) { OS << "\n Parent : " << *ParentFunction; } if (!Fragments.empty()) { OS << "\n Fragments : "; auto Sep = ""; for (auto *Frag : Fragments) { OS << Sep << *Frag; Sep = ", "; } } if (hasCFG()) { OS << "\n Hash : " << Twine::utohexstr(computeHash()); } if (isMultiEntry()) { OS << "\n Secondary Entry Points : "; auto Sep = ""; for (auto &KV : SecondaryEntryPoints) { OS << Sep << KV.second->getName(); Sep = ", "; } } if (FrameInstructions.size()) { OS << "\n CFI Instrs : " << FrameInstructions.size(); } if (BasicBlocksLayout.size()) { OS << "\n BB Layout : "; auto Sep = ""; for (auto BB : BasicBlocksLayout) { OS << Sep << BB->getName(); Sep = ", "; } } if (ImageAddress) OS << "\n Image : 0x" << Twine::utohexstr(ImageAddress); if (ExecutionCount != COUNT_NO_PROFILE) { OS << "\n Exec Count : " << ExecutionCount; OS << "\n Profile Acc : " << format("%.1f%%", ProfileMatchRatio * 100.0f); } if (opts::PrintDynoStats && !BasicBlocksLayout.empty()) { OS << '\n'; DynoStats dynoStats = getDynoStats(*this); OS << dynoStats; } OS << "\n}\n"; if (opts::PrintDynoStatsOnly || !PrintInstructions || !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 auto &II : Instructions) { Offset = II.first; // Print label if exists at this offset. auto LI = Labels.find(Offset); if (LI != Labels.end()) { if (const auto *EntrySymbol = getSecondaryEntryPointSymbol(LI->second)) OS << EntrySymbol->getName() << " (Entry Point):\n"; OS << LI->second->getName() << ":\n"; } BC.printInstruction(OS, II.second, Offset, this); } } for (uint32_t I = 0, E = BasicBlocksLayout.size(); I != E; ++I) { auto BB = BasicBlocksLayout[I]; if (I != 0 && BB->isCold() != BasicBlocksLayout[I - 1]->isCold()) OS << "------- HOT-COLD SPLIT POINT -------\n\n"; OS << BB->getName() << " (" << BB->size() << " instructions, align : " << BB->getAlignment() << ")\n"; if (isEntryPoint(*BB)) { if (auto *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 (BB->getCFIState() >= 0) { OS << " CFI State : " << BB->getCFIState() << '\n'; } if (opts::EnableBAT) { OS << " Input offset: " << Twine::utohexstr(BB->getInputOffset()) << "\n"; } if (!BB->pred_empty()) { OS << " Predecessors: "; auto Sep = ""; for (auto Pred : BB->predecessors()) { OS << Sep << Pred->getName(); Sep = ", "; } OS << '\n'; } if (!BB->throw_empty()) { OS << " Throwers: "; auto Sep = ""; for (auto Throw : BB->throwers()) { OS << Sep << Throw->getName(); Sep = ", "; } 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()) { std::stable_sort(Indices.begin(), Indices.end(), [&](const uint64_t A, const uint64_t B) { return BB->BranchInfo[B] < BB->BranchInfo[A]; }); } auto Sep = ""; for (unsigned I = 0; I < Indices.size(); ++I) { auto *Succ = BB->Successors[Indices[I]]; auto &BI = BB->BranchInfo[Indices[I]]; OS << Sep << 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 << ")"; } Sep = ", "; } OS << '\n'; } if (!BB->lp_empty()) { OS << " Landing Pads: "; auto Sep = ""; for (auto LP : BB->landing_pads()) { OS << Sep << LP->getName(); if (ExecutionCount != COUNT_NO_PROFILE) { OS << " (count: " << LP->getExecutionCount() << ")"; } Sep = ", "; } OS << '\n'; } // In CFG_Finalized state we can miscalculate CFI state at exit. if (CurrentState == State::CFG) { const auto 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 (auto &CSI : CallSites) { 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 (auto &JTI : JumpTables) { JTI.second->print(OS); } OS << "DWARF CFI Instructions:\n"; if (OffsetToCFI.size()) { // Pre-buildCFG information for (auto &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; } RI = MoveRelocations.lower_bound(Offset); while (RI != MoveRelocations.end() && RI->first < Offset + Size) { OS << Sep << "(M: " << RI->second << ")"; Sep = ", "; ++RI; } } IndirectBranchType BinaryFunction::processIndirectBranch(MCInst &Instruction, unsigned Size, uint64_t Offset, uint64_t &TargetAddress) { const auto PtrSize = BC.AsmInfo->getCodePointerSize(); // An instruction referencing memory used by jump instruction (directly or // via register). This location could be an array of function pointers // in case of indirect tail call, or a jump table. MCInst *MemLocInstr; // 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()) { PreserveNops = BC.HasRelocations; // 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 (auto LI = Labels.rbegin(); LI != Labels.rend(); ++LI) { auto II = Instructions.find(LI->first); if (II != Instructions.end()) { Begin = II; break; } } } auto Type = BC.MIB->analyzeIndirectBranch(Instruction, Begin, Instructions.end(), PtrSize, MemLocInstr, BaseRegNum, IndexRegNum, DispValue, DispExpr, PCRelBaseInstr); if (Type == IndirectBranchType::UNKNOWN && !MemLocInstr) return Type; if (MemLocInstr != &Instruction) IndexRegNum = BC.MIB->getNoRegister(); if (BC.isAArch64()) { const auto *Sym = BC.MIB->getTargetSymbol(*PCRelBaseInstr, 1); assert (Sym && "Symbol extraction failed"); auto SymValueOrError = BC.getSymbolValue(*Sym); if (SymValueOrError) { PCRelAddr = *SymValueOrError; } else { for (auto &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; } // RIP-relative addressing should be converted to symbol form by now // in processed instructions (but not in jump). if (DispExpr) { const MCSymbol *TargetSym; uint64_t TargetOffset; std::tie(TargetSym, TargetOffset) = BC.MIB->getTargetSymbolInfo(DispExpr); auto SymValueOrError = BC.getSymbolValue(*TargetSym); assert(SymValueOrError && "global symbol needs a value"); ArrayStart = *SymValueOrError + TargetOffset; 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; DEBUG(dbgs() << "BOLT-DEBUG: addressed memory is 0x" << Twine::utohexstr(ArrayStart) << '\n'); auto 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) { 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 (Type == IndirectBranchType::POSSIBLE_FIXED_BRANCH) { auto Value = BC.getPointerAtAddress(ArrayStart); if (!Value) return IndirectBranchType::UNKNOWN; if (!BC.getSectionForAddress(ArrayStart)->isReadOnly()) return IndirectBranchType::UNKNOWN; 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 Type; } auto useJumpTableForInstruction = [&](JumpTable::JumpTableType JTType) { const MCSymbol *JTLabel = BC.getOrCreateJumpTable(*this, ArrayStart, JTType); BC.MIB->replaceMemOperandDisp(const_cast(*MemLocInstr), JTLabel, BC.Ctx.get()); BC.MIB->setJumpTable(Instruction, ArrayStart, IndexRegNum); JTSites.emplace_back(Offset, ArrayStart); }; // Check if there's already a jump table registered at this address. // At this point, all jump tables are empty. if (auto *JT = BC.getJumpTableContainingAddress(ArrayStart)) { // Make sure the type of the table matches the code. if (Type == IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE) { assert(JT->Type == JumpTable::JTT_PIC && "PIC jump table expected"); } else { assert(JT->Type == JumpTable::JTT_NORMAL && "normal jump table expected"); Type = IndirectBranchType::POSSIBLE_JUMP_TABLE; } useJumpTableForInstruction(JT->Type); return Type; } const auto MemType = BC.analyzeMemoryAt(ArrayStart, *this); if (Type == IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE) { assert(MemType == MemoryContentsType::POSSIBLE_PIC_JUMP_TABLE && "PIC jump table heuristic failure"); useJumpTableForInstruction(JumpTable::JTT_PIC); return Type; } if (MemType == MemoryContentsType::POSSIBLE_JUMP_TABLE) { assert(Type == IndirectBranchType::UNKNOWN && "non-PIC jump table heuristic failure"); useJumpTableForInstruction(JumpTable::JTT_NORMAL); return IndirectBranchType::POSSIBLE_JUMP_TABLE; } // We have a possible tail call, so let's add the value read from the possible // memory location as a reference. Only do that if the address we read is sane // enough (is inside an allocatable section). It is possible that we read // garbage if the load instruction we analyzed is in a basic block different // than the one where the indirect jump is. However, later, // postProcessIndirectBranches() is going to mark the function as non-simple // in this case. auto Value = BC.getPointerAtAddress(ArrayStart); if (Value && BC.getSectionForAddress(*Value)) BC.InterproceduralReferences.insert(std::make_pair(this, *Value)); return IndirectBranchType::POSSIBLE_TAIL_CALL; } MCSymbol *BinaryFunction::getOrCreateLocalLabel(uint64_t Address, bool CreatePastEnd) { const auto 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; } } auto *Label = BC.Ctx->createTempSymbol(); Labels[Offset] = Label; return Label; } ErrorOr> BinaryFunction::getData() const { auto &Section = getSection(); 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. auto 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.DataOffsets.find(Offset) == Islands.DataOffsets.end()) 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(); auto Iter = Islands.DataOffsets.upper_bound(Offset); if (Iter != Islands.DataOffsets.end()) EndOfCode = *Iter; for (auto I = Offset; I < EndOfCode; ++I) { if (FunctionData[I] != 0) { return false; } } return true; } void 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; DWARFUnitLineTable ULT = getDWARFUnitLineTable(); matchProfileMemData(); // Insert a label at the beginning of the function. This will be our first // basic block. Labels[0] = Ctx->createTempSymbol("BB0", false); auto handlePCRelOperand = [&](MCInst &Instruction, uint64_t Address, uint64_t Size) { uint64_t TargetAddress{0}; if (!MIB->evaluateMemOperandTarget(Instruction, TargetAddress, Address, Size)) { errs() << "BOLT-ERROR: PC-relative operand can't be evaluated:\n"; BC.InstPrinter->printInst(&Instruction, errs(), "", *BC.STI); errs() << '\n'; Instruction.dump_pretty(errs(), BC.InstPrinter.get()); errs() << '\n'; return false; } if (TargetAddress == 0 && opts::Verbosity >= 1) { 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); const MCExpr *Expr = MCSymbolRefExpr::create(TargetSymbol, MCSymbolRefExpr::VK_None, *BC.Ctx); if (TargetOffset) { auto *Offset = MCConstantExpr::create(TargetOffset, *BC.Ctx); Expr = MCBinaryExpr::createAdd(Expr, Offset, *BC.Ctx); } MIB->replaceMemOperandDisp( Instruction, MCOperand::createExpr(BC.MIB->getTargetExprFor( Instruction, Expr, *BC.Ctx, 0))); return true; }; // Used to fix the target of linker-generated AArch64 stubs with no relocation // info auto fixStubTarget = [&](MCInst &LoadLowBits, MCInst &LoadHiBits, uint64_t Target) { const MCSymbol *TargetSymbol; uint64_t Addend{0}; std::tie(TargetSymbol, Addend) = BC.handleAddressRef(Target, *this, true); int64_t Val; MIB->replaceImmWithSymbolRef(LoadHiBits, TargetSymbol, Addend, Ctx.get(), Val, ELF::R_AARCH64_ADR_PREL_PG_HI21); MIB->replaceImmWithSymbolRef(LoadLowBits, TargetSymbol, Addend, Ctx.get(), Val, ELF::R_AARCH64_ADD_ABS_LO12_NC); }; 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 auto DataInCodeSize = getSizeOfDataInCodeAt(Offset)) { Size = DataInCodeSize; continue; } if (!BC.DisAsm->getInstruction(Instruction, Size, FunctionData.slice(Offset), AbsoluteInstrAddr, nulls(), nulls())) { // Functions with "soft" boundaries, e.g. coming from assembly source, // can have 0-byte padding at the end. if (isZeroPaddingAt(Offset)) break; 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 { IsSimple = false; } break; } // Check integrity of LLVM assembler/disassembler. if (opts::CheckEncoding && !BC.MIB->isBranch(Instruction) && !BC.MIB->isCall(Instruction) && !BC.MIB->isNoop(Instruction)) { if (!BC.validateEncoding(Instruction, FunctionData.slice(Offset, Size))) { errs() << "BOLT-WARNING: mismatching LLVM encoding detected in " << "function " << *this << " for instruction :\n"; BC.printInstruction(errs(), Instruction, AbsoluteInstrAddr); errs() << '\n'; } } // Special handling for AVX-512 instructions. if (MIB->hasEVEXEncoding(Instruction)) { if (BC.HasRelocations && opts::TrapOnAVX512) { setTrapOnEntry(); BC.TrappedFunctions.push_back(this); break; } // Check if our disassembly is correct and matches the assembler output. if (!BC.validateEncoding(Instruction, FunctionData.slice(Offset, Size))) { if (BC.HasRelocations) { errs() << "BOLT-ERROR: internal assembler/disassembler error " "detected for AVX512 instruction:\n"; BC.printInstruction(errs(), Instruction, AbsoluteInstrAddr); errs() << " in function " << *this << '\n'; exit(1); } else { setSimple(false); break; } } } // Check if there's a relocation associated with this instruction. bool UsedReloc{false}; for (auto Itr = Relocations.lower_bound(Offset); Itr != Relocations.upper_bound(Offset + Size); ++Itr) { const auto &Relocation = Itr->second; if (Relocation.Offset >= Offset + Size) continue; const MCSymbol *TargetSymbol = Relocation.Symbol; auto Addend = Relocation.Addend; DEBUG(dbgs() << "BOLT-DEBUG: replacing immediate 0x" << Twine::utohexstr(Relocation.Value) << " with relocation" " against " << TargetSymbol->getName() << "+" << Addend << " in function " << *this << " for instruction at offset 0x" << Twine::utohexstr(Offset) << '\n'); int64_t Value = Relocation.Value; // Process reference to the primary symbol. if (!Relocation.isPCRelative()) BC.handleAddressRef(Relocation.Value - Relocation.Addend, *this, /*IsPCRel*/ false); const auto Result = BC.MIB->replaceImmWithSymbolRef(Instruction, Relocation.Symbol, Relocation.Addend, Ctx.get(), Value, Relocation.Type); (void)Result; assert(Result && "cannot replace immediate with relocation"); // For aarch, 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. if (BC.isAArch64()) UsedReloc = true; // Make sure we replaced the correct immediate (instruction // can have multiple immediate operands). if (BC.isX86()) { assert(truncateToSize(static_cast(Value), Relocation::getSizeForType(Relocation.Type)) == truncateToSize(Relocation.Value, Relocation::getSizeForType(Relocation.Type)) && "immediate value mismatch in function"); } } // Convert instruction to a shorter version that could be relaxed if // needed. MIB->shortenInstruction(Instruction); 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 (IsCall && containsAddress(TargetAddress)) { if (TargetAddress == getAddress()) { // Recursive call. TargetSymbol = getSymbol(); } else { if (BC.isX86()) { // Dangerous old-style x86 PIC code. We may need to freeze this // function, so preserve the function as is for now. PreserveNops = true; } else { errs() << "BOLT-WARNING: internal call detected at 0x" << Twine::utohexstr(AbsoluteInstrAddr) << " in function " << *this << ". Skipping.\n"; IsSimple = false; } } } if (!TargetSymbol) { // Create either local label or external symbol. if (containsAddress(TargetAddress)) { TargetSymbol = getOrCreateLocalLabel(TargetAddress); } else { if (TargetAddress == getAddress() + getSize() && TargetAddress < getAddress() + getMaxSize()) { // Result of __builtin_unreachable(). 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; } BC.InterproceduralReferences.insert( std::make_pair(this, TargetAddress)); if (opts::Verbosity >= 2 && !IsCall && Size == 2 && !BC.HasRelocations) { 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(IsCondBranch && "unknown tail call instruction"); if (opts::Verbosity >= 2) { errs() << "BOLT-WARNING: conditional tail call detected in " << "function " << *this << " at 0x" << Twine::utohexstr(AbsoluteInstrAddr) << ".\n"; } } IsCall = true; } TargetSymbol = BC.getOrCreateGlobalSymbol(TargetAddress, "FUNCat"); if (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. if (opts::Verbosity >= 2) { outs() << "BOLT-INFO: Function " << *this << " has a call to address zero.\n"; } } if (BC.HasRelocations) { // Check if we need to create relocation to move this function's // code without re-assembly. size_t RelSize = (Size < 5) ? 1 : 4; auto RelOffset = Offset + Size - RelSize; if (BC.isAArch64()) { RelSize = 0; RelOffset = Offset; } auto RI = MoveRelocations.find(RelOffset); if (RI == MoveRelocations.end()) { uint64_t RelType = (RelSize == 1) ? ELF::R_X86_64_PC8 : ELF::R_X86_64_PC32; if (BC.isAArch64()) RelType = ELF::R_AARCH64_CALL26; DEBUG(dbgs() << "BOLT-DEBUG: creating relocation for static" << " function call to " << TargetSymbol->getName() << " at offset 0x" << Twine::utohexstr(RelOffset) << " with size " << RelSize << " for function " << *this << '\n'); addRelocation(getAddress() + RelOffset, TargetSymbol, RelType, -RelSize, 0); } } } } 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)) { uint64_t IndirectTarget{0}; auto Result = processIndirectBranch(Instruction, Size, Offset, IndirectTarget); switch (Result) { default: llvm_unreachable("unexpected result"); case IndirectBranchType::POSSIBLE_TAIL_CALL: { auto Result = MIB->convertJmpToTailCall(Instruction); (void)Result; assert(Result); break; } case IndirectBranchType::POSSIBLE_JUMP_TABLE: case IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE: if (opts::JumpTables == JTS_NONE) IsSimple = false; break; case IndirectBranchType::POSSIBLE_FIXED_BRANCH: { if (containsAddress(IndirectTarget)) { const auto *TargetSymbol = getOrCreateLocalLabel(IndirectTarget); Instruction.clear(); MIB->createUncondBranch(Instruction, TargetSymbol, BC.Ctx.get()); TakenBranches.emplace_back(Offset, IndirectTarget - getAddress()); HasFixedIndirectBranch = true; } else { MIB->convertJmpToTailCall(Instruction); BC.InterproceduralReferences.insert( std::make_pair(this, IndirectTarget)); } break; } case IndirectBranchType::UNKNOWN: // Keep processing. We'll do more checks and fixes in // postProcessIndirectBranches(). UnknownIndirectBranchOffsets.emplace(Offset); break; }; } // Indirect call. We only need to fix it if the operand is RIP-relative. if (IsSimple && MIB->hasPCRelOperand(Instruction)) { if (!handlePCRelOperand(Instruction, AbsoluteInstrAddr, Size)) { errs() << "BOLT-ERROR: cannot handle PC-relative operand at 0x" << Twine::utohexstr(AbsoluteInstrAddr) << ". Skipping function " << *this << ".\n"; if (BC.HasRelocations) exit(1); IsSimple = false; } } // AArch64 indirect call - check for linker veneers, which lack // relocations and need manual adjustments MCInst *TargetHiBits, *TargetLowBits; uint64_t TargetAddress; if (BC.isAArch64() && MIB->matchLinkerVeneer(Instructions.begin(), Instructions.end(), AbsoluteInstrAddr, Instruction, TargetHiBits, TargetLowBits, TargetAddress)) { MIB->addAnnotation(Instruction, "AArch64Veneer", true); uint8_t Counter = 0; for (auto It = std::prev(Instructions.end()); Counter != 2; --It, ++Counter) { MIB->addAnnotation(It->second, "AArch64Veneer", true); } fixStubTarget(*TargetLowBits, *TargetHiBits, TargetAddress); } } } else { if (MIB->hasPCRelOperand(Instruction) && !UsedReloc) { if (!handlePCRelOperand(Instruction, AbsoluteInstrAddr, Size)) { errs() << "BOLT-ERROR: cannot handle PC-relative operand at 0x" << Twine::utohexstr(AbsoluteInstrAddr) << ". Skipping function " << *this << ".\n"; if (BC.HasRelocations) exit(1); IsSimple = false; } } } add_instruction: if (ULT.first && ULT.second) { Instruction.setLoc( findDebugLineInformationForInstructionAt(AbsoluteInstrAddr, ULT)); } // Record offset of the instruction for profile matching. if (BC.keepOffsetForInstruction(Instruction)) { MIB->addAnnotation(Instruction, "Offset", static_cast(Offset)); } if (MemData && !emptyRange(MemData->getMemInfoRange(Offset))) { MIB->addAnnotation(Instruction, "MemDataOffset", Offset); } addInstruction(Offset, std::move(Instruction)); } clearList(Relocations); updateState(State::Disassembled); } void BinaryFunction::scanExternalRefs() { if (isPLTFunction()) return; 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"); 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 auto DataInCodeSize = getSizeOfDataInCodeAt(Offset)) { Size = DataInCodeSize; continue; } const uint64_t AbsoluteInstrAddr = getAddress() + Offset; MCInst Instruction; if (!BC.DisAsm->getInstruction(Instruction, Size, FunctionData.slice(Offset), AbsoluteInstrAddr, nulls(), nulls())) { if (opts::Verbosity >= 1 && !isZeroPaddingAt(Offset)) { errs() << "BOLT-WARNING: unable to disassemble instruction at offset 0x" << Twine::utohexstr(Offset) << " (address 0x" << Twine::utohexstr(AbsoluteInstrAddr) << ") in function " << *this << '\n'; } break; } // Detect address reference by an instruction. // Without relocations, we can only trust PC-relative address modes. uint64_t TargetAddress{0}; if (BC.MIB->hasPCRelOperand(Instruction)) { if (!BC.MIB->evaluateMemOperandTarget(Instruction, TargetAddress, AbsoluteInstrAddr, Size)) { continue; } } else if (BC.MIB->isCall(Instruction) || BC.MIB->isBranch(Instruction)) { if (!BC.MIB->evaluateBranch(Instruction, AbsoluteInstrAddr, Size, TargetAddress)) { continue; } } else { continue; } if (containsAddress(TargetAddress, /*UseMaxSize=*/true)) continue; auto *TargetFunction = BC.getBinaryFunctionContainingAddress(TargetAddress); if (!TargetFunction) continue; const uint64_t TargetOffset = TargetAddress - TargetFunction->getAddress(); if (TargetOffset && TargetFunction->isSimple()) { TargetFunction->addEntryPointAtOffset(TargetOffset); } } } void BinaryFunction::postProcessEntryPoints() { if (!isSimple()) return; for (auto &KV : Labels) { auto *Label = KV.second; if (!getSecondaryEntryPointSymbol(Label)) continue; const auto 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; } errs() << "BOLT-WARNING: reference in the middle of instruction " "detected in function " << *this << " at offset 0x" << Twine::utohexstr(Offset) << '\n'; if (BC.HasRelocations) { errs() << "BOLT-ERROR: unable to keep processing in relocation mode\n"; exit(1); } setSimple(false); } } void BinaryFunction::postProcessJumpTables() { // Create labels for all entries. for (auto &JTI : JumpTables) { auto &JT = *JTI.second; if (JT.Type == JumpTable::JTT_PIC && opts::JumpTables == JTS_BASIC) { opts::JumpTables = JTS_MOVE; outs() << "BOLT-INFO: forcing -jump-tables=move as PIC jump table was " "detected in function " << *this << '\n'; } for (unsigned I = 0; I < JT.OffsetEntries.size(); ++I) { auto *Label = getOrCreateLocalLabel(getAddress() + JT.OffsetEntries[I], /*CreatePastEnd*/ true); JT.Entries.push_back(Label); } const auto 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"); } } // 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 auto JTSiteOffset = JTSite.first; const auto JTAddress = JTSite.second; const auto *JT = getJumpTableContainingAddress(JTAddress); assert(JT && "cannot find jump table for address"); auto EntryOffset = JTAddress - JT->getAddress(); while (EntryOffset < JT->getSize()) { auto TargetOffset = JT->OffsetEntries[EntryOffset / JT->EntrySize]; if (TargetOffset < getSize()) { TakenBranches.emplace_back(JTSiteOffset, TargetOffset); if (opts::StrictMode) registerReferencedOffset(TargetOffset); } // Take ownership of jump table relocations. if (BC.HasRelocations) { auto EntryAddress = JT->getAddress() + EntryOffset; auto Res = BC.removeRelocationAt(EntryAddress); (void)Res; DEBUG( auto Section = BC.getSectionForAddress(EntryAddress); auto Offset = EntryAddress - Section->getAddress(); dbgs() << "BOLT-DEBUG: removing relocation from section " << Section->getName() << " at offset 0x" << Twine::utohexstr(Offset) << " = " << Res << '\n'); } EntryOffset += JT->EntrySize; // A label at the next entry means the end of this jump table. if (JT->Labels.count(EntryOffset)) break; } } clearList(JTSites); // Free memory used by jump table offsets. for (auto &JTI : JumpTables) { auto &JT = *JTI.second; clearList(JT.OffsetEntries); } // Conservatively populate all possible destinations for unknown indirect // branches. if (opts::StrictMode && hasInternalReference()) { for (auto Offset : UnknownIndirectBranchOffsets) { for (auto PossibleDestination : ExternallyReferencedOffsets) { // Ignore __builtin_unreachable(). if (PossibleDestination == getSize()) continue; TakenBranches.emplace_back(Offset, PossibleDestination); } } } // Remove duplicates branches. We can get a bunch of them from jump tables. // Without doing jump table value profiling we don't have use for extra // (duplicate) branches. std::sort(TakenBranches.begin(), TakenBranches.end()); auto NewEnd = std::unique(TakenBranches.begin(), TakenBranches.end()); TakenBranches.erase(NewEnd, TakenBranches.end()); } bool BinaryFunction::postProcessIndirectBranches( MCPlusBuilder::AllocatorIdTy AllocId) { auto addUnknownControlFlow = [&](BinaryBasicBlock &BB) { HasUnknownControlFlow = true; BB.removeAllSuccessors(); for (auto PossibleDestination : ExternallyReferencedOffsets) { if (auto *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 (auto *BB : layout()) { for (auto &Instr : *BB) { if (!BC.MIB->isIndirectBranch(Instr)) continue; // If there's an indirect branch in a single-block function - // it must be a tail call. if (layout_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 auto PtrSize = BC.AsmInfo->getCodePointerSize(); MCInst *MemLocInstr; unsigned BaseRegNum, IndexRegNum; int64_t DispValue; const MCExpr *DispExpr; MCInst *PCRelBaseInstr; auto Type = BC.MIB->analyzeIndirectBranch(Instr, BB->begin(), BB->end(), PtrSize, MemLocInstr, BaseRegNum, IndexRegNum, DispValue, DispExpr, PCRelBaseInstr); 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); auto *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. 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 = false; for (const auto &Instr : *BB) { if (BC.MIB->isLeave(Instr) || BC.MIB->isPop(Instr)) { IsEpilogue = true; break; } } if (IsEpilogue) { BC.MIB->convertJmpToTailCall(Instr); BB->removeAllSuccessors(); continue; } if (opts::Verbosity >= 2) { outs() << "BOLT-INFO: rejected potential indirect tail call in " << "function " << *this << " in basic block " << BB->getName() << ".\n"; 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.MIB->setJumpTable(*LastIndirectJump, LastJT, LastJTIndexReg, AllocId); HasUnknownControlFlow = false; // re-populate successors based on the jump table. std::set JTLabels; LastIndirectJumpBB->removeAllSuccessors(); const auto *JT = getJumpTableContainingAddress(LastJT); for (const auto *Label : JT->Entries) { JTLabels.emplace(Label); } for (const auto *Label : JTLabels) { auto *BB = getBasicBlockForLabel(Label); // Ignore __builtin_unreachable() if (!BB) { assert(Label == getFunctionEndLabel() && "if no BB found, must be end"); continue; } LastIndirectJumpBB->addSuccessor(BB); } } if (HasFixedIndirectBranch) return false; if (HasUnknownControlFlow && !BC.HasRelocations) return false; return true; } void BinaryFunction::recomputeLandingPads() { updateBBIndices(0); for (auto *BB : BasicBlocks) { BB->LandingPads.clear(); BB->Throwers.clear(); } for (auto *BB : BasicBlocks) { std::unordered_set BBLandingPads; for (auto &Instr : *BB) { if (!BC.MIB->isInvoke(Instr)) continue; const auto EHInfo = BC.MIB->getEHInfo(Instr); if (!EHInfo || !EHInfo->first) continue; auto *LPBlock = getBasicBlockForLabel(EHInfo->first); if (!BBLandingPads.count(LPBlock)) { BBLandingPads.insert(LPBlock); BB->LandingPads.emplace_back(LPBlock); LPBlock->Throwers.emplace_back(BB); } } } } bool 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 false; } if (CurrentState != State::Disassembled) return false; assert(BasicBlocks.empty() && "basic block list should be empty"); assert((Labels.find(0) != 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}; 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. But in certain cases we don't if the instruction was // the last one, and we have to go back and update its offset. auto updateOffset = [&](uint64_t Offset) { assert(PrevBB && PrevBB != InsertBB && "invalid previous block"); auto *PrevInstr = PrevBB->getLastNonPseudoInstr(); if (PrevInstr && !MIB->hasAnnotation(*PrevInstr, "Offset")) MIB->addAnnotation(*PrevInstr, "Offset", static_cast(Offset), AllocatorId); }; for (auto I = Instructions.begin(), E = Instructions.end(); I != E; ++I) { const auto Offset = I->first; auto &Instr = I->second; auto LI = Labels.find(Offset); if (LI != Labels.end()) { // Always create new BB at branch destination. PrevBB = InsertBB; InsertBB = addBasicBlock(LI->first, LI->second, opts::PreserveBlocksAlignment && IsLastInstrNop); if (PrevBB) updateOffset(LastInstrOffset); } const auto InstrInputAddr = I->first + Address; bool IsSDTMarker = MIB->isNoop(Instr) && BC.SDTMarkers.count(InstrInputAddr); if (IsSDTMarker) { HasSDTMarker = true; DEBUG(dbgs() << "SDTMarker detected in the input at : " << utohexstr(InstrInputAddr) << "\n"); if (!MIB->hasAnnotation(Instr, "Offset")) { MIB->addAnnotation(Instr, "Offset", static_cast(Offset), AllocatorId); } } // Ignore nops except SDT markers. We use nops to derive alignment of the // next basic block. It will not always work, as some blocks are naturally // aligned, but it's just part of heuristic for block alignment. if (MIB->isNoop(Instr) && !PreserveNops && !IsSDTMarker) { IsLastInstrNop = true; continue; } 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"); auto *PrevInstr = PrevBB->getLastNonPseudoInstr(); assert(PrevInstr && "no previous instruction for a fall through"); if (MIB->isUnconditionalBranch(Instr) && !MIB->isUnconditionalBranch(*PrevInstr) && !MIB->getConditionalTailCall(*PrevInstr)) { // Temporarily restore inserter basic block. InsertBB = PrevBB; } else { MCSymbol *Label; { auto L = BC.scopeLock(); Label = BC.Ctx->createTempSymbol("FT", true); } InsertBB = addBasicBlock( Offset, Label, opts::PreserveBlocksAlignment && IsLastInstrNop); updateOffset(LastInstrOffset); } } if (Offset == 0) { // Add associated CFI pseudos in the first offset (0) addCFIPlaceholders(0, InsertBB); } const auto IsBlockEnd = MIB->isTerminator(Instr); IsLastInstrNop = MIB->isNoop(Instr); 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 false; } // Intermediate dump. 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. for (auto &Branch : TakenBranches) { DEBUG(dbgs() << "registering branch [0x" << Twine::utohexstr(Branch.first) << "] -> [0x" << Twine::utohexstr(Branch.second) << "]\n"); auto *FromBB = getBasicBlockContainingOffset(Branch.first); auto *ToBB = getBasicBlockAtOffset(Branch.second); if (!FromBB || !ToBB) { if (!FromBB) errs() << "BOLT-ERROR: cannot find BB containing the branch.\n"; if (!ToBB) errs() << "BOLT-ERROR: cannot find BB containing branch destination.\n"; BC.exitWithBugReport("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 (auto BB : BasicBlocks) { if (IsPrevFT) { PrevBB->addSuccessor(BB); } if (BB->empty()) { IsPrevFT = true; PrevBB = BB; continue; } auto 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; } if (!IsPrevFT) { // Possibly a call that does not return. DEBUG(dbgs() << "last block was marked as a fall-through in " << *this << '\n'); } // 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 (auto BB : BasicBlocks) { BasicBlocksLayout.emplace_back(BB); if (PrevBB) PrevBB->setEndOffset(BB->getOffset()); PrevBB = BB; } PrevBB->setEndOffset(getSize()); 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) { errs() << "BOLT-WARNING: failed to post-process indirect branches for " << *this << '\n'; } // In relocation mode we want to keep processing the function but avoid // optimizing it. setSimple(false); } clearList(ExternallyReferencedOffsets); clearList(UnknownIndirectBranchOffsets); return true; } 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(); } calculateMacroOpFusionStats(); // 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 (auto *BB : layout()) for (auto &Inst : *BB) BC.MIB->removeAnnotation(Inst, "Offset"); assert((!isSimple() || validateCFG()) && "invalid CFG detected after post-processing"); } void BinaryFunction::calculateMacroOpFusionStats() { if (!getBinaryContext().isX86()) return; for (auto *BB : layout()) { auto II = BB->getMacroOpFusionPair(); if (II == BB->end()) continue; // Check offset of the second instruction. // FIXME: arch-specific. const auto Offset = BC.MIB->getAnnotationWithDefault(*std::next(II), "Offset", 0); if (!Offset || (getAddress() + Offset) % 64) continue; DEBUG(dbgs() << "\nmissed macro-op fusion at address 0x" << Twine::utohexstr(getAddress() + Offset) << " in function " << *this << "; executed " << BB->getKnownExecutionCount() << " times.\n"); ++BC.MissedMacroFusionPairs; BC.MissedMacroFusionExecCount += BB->getKnownExecutionCount(); } } void BinaryFunction::removeTagsFromProfile() { for (auto *BB : BasicBlocks) { if (BB->ExecutionCount == BinaryBasicBlock::COUNT_NO_PROFILE) BB->ExecutionCount = 0; for (auto &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) { auto &BB = *BBI; auto *CTCInstr = BB.getLastNonPseudoInstr(); if (!CTCInstr) continue; auto TargetAddressOrNone = BC.MIB->getConditionalTailCall(*CTCInstr); if (!TargetAddressOrNone) continue; // Gather all necessary information about CTC instruction before // annotations are destroyed. const auto 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 auto *CTCTargetLabel = BC.MIB->getTargetSymbol(*CTCInstr); assert(CTCTargetLabel && "symbol expected for conditional tail call"); MCInst TailCallInstr; BC.MIB->createTailCall(TailCallInstr, CTCTargetLabel, BC.Ctx.get()); // 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) auto TailCallBB = createBasicBlock(BB.getInputOffset(), BC.Ctx->createTempSymbol("TC", true)); 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 (auto BB : layout()) { uint64_t BBExecCount = BB->getExecutionCount(); if (BBExecCount == BinaryBasicBlock::COUNT_NO_PROFILE) continue; TotalScore += BBExecCount; } 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 (auto *BB : BasicBlocks) { BB->setCFIState(EffectiveState); for (const auto &Instr : *BB) { const auto *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; } } } assert(StateStack.empty() && "corrupt CFI stack"); } 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 std::vector &CIE; const std::vector &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: case MCCFIInstruction::OpExpression: case MCCFIInstruction::OpValExpression: RegRule[Instr.getRegister()] = RuleNumber; break; case MCCFIInstruction::OpDefCfaRegister: CFAReg = Instr.getRegister(); CFARule = UNKNOWN; break; case MCCFIInstruction::OpDefCfaOffset: CFAOffset = Instr.getOffset(); CFARule = UNKNOWN; break; case MCCFIInstruction::OpDefCfa: CFAReg = Instr.getRegister(); CFAOffset = Instr.getOffset(); CFARule = UNKNOWN; break; case MCCFIInstruction::OpDefCfaExpression: CFARule = RuleNumber; break; case MCCFIInstruction::OpAdjustCfaOffset: case MCCFIInstruction::OpWindowSave: case MCCFIInstruction::OpEscape: 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 auto &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 std::vector &CIE, const std::vector &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 auto &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 std::vector &CIE, const std::vector &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::OpExpression: case MCCFIInstruction::OpValExpression: { if (RestoredRegs[Instr.getRegister()]) return true; RestoredRegs[Instr.getRegister()] = true; const int32_t CurRegRule = RegRule.find(Instr.getRegister()) != RegRule.end() ? RegRule[Instr.getRegister()] : 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::OpDefCfaExpression: if (RestoredCFAReg && RestoredCFAOffset) return true; RestoredCFAReg = true; RestoredCFAOffset = true; return false; case MCCFIInstruction::OpAdjustCfaOffset: case MCCFIInstruction::OpWindowSave: case MCCFIInstruction::OpEscape: 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 (auto 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); continue; } // Replay instructions while avoiding duplicates for (auto I = NewCFIs.rbegin(), E = NewCFIs.rend(); I != E; ++I) { if (CFIDiff.isRedundant(FrameInstructions[*I])) continue; InsertIt = addCFIPseudo(InBB, InsertIt, *I); } 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 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::OpRegister: case MCCFIInstruction::OpExpression: case MCCFIInstruction::OpValExpression: { if (ToCFITable.RegRule.find(Instr.getRegister()) == ToCFITable.RegRule.end()) { FrameInstructions.emplace_back( MCCFIInstruction::createRestore(nullptr, Instr.getRegister())); 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[Instr.getRegister()]; 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: case MCCFIInstruction::OpDefCfaExpression: if (ToCFITable.CFARule == CFISnapshot::UNKNOWN) { FrameInstructions.emplace_back(MCCFIInstruction::createDefCfa( nullptr, ToCFITable.CFAReg, -ToCFITable.CFAOffset)); if (FromCFITable.isRedundant(FrameInstructions.back())) { FrameInstructions.pop_back(); break; } 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])) break; 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; } break; case MCCFIInstruction::OpAdjustCfaOffset: case MCCFIInstruction::OpWindowSave: case MCCFIInstruction::OpEscape: 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 auto &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 : BasicBlocksLayout) { for (auto II = CurBB->begin(); II != CurBB->end(); ++II) { if (auto *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() { DEBUG(dbgs() << "Trying to fix CFI states for each BB after reordering.\n"); DEBUG(dbgs() << "This is the list of CFI states for each BB of " << *this << ": "); int32_t State = 0; bool SeenCold = false; auto Sep = ""; (void)Sep; for (auto *BB : BasicBlocksLayout) { const auto CFIStateAtExit = BB->getCFIStateAtExit(); // Hot-cold border: check if this is the first BB to be allocated in a cold // region (with a different FDE). If yes, we need to reset the CFI state. if (!SeenCold && BB->isCold()) { State = 0; SeenCold = true; } // 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; DEBUG(dbgs() << Sep << State; Sep = ", "); } DEBUG(dbgs() << "\n"); for (auto BB : BasicBlocksLayout) { for (auto II = BB->begin(); II != BB->end(); ) { auto 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(); } uint64_t BinaryFunction::getInstructionCount() const { uint64_t Count = 0; for (auto &Block : BasicBlocksLayout) { Count += Block->getNumNonPseudos(); } return Count; } bool BinaryFunction::hasLayoutChanged() const { return ModifiedLayout; } uint64_t BinaryFunction::getEditDistance() const { return ComputeEditDistance(BasicBlocksPreviousLayout, BasicBlocksLayout); } void BinaryFunction::setTrapOnEntry() { clearList(Instructions); clearList(IgnoredBranches); clearList(TakenBranches); auto addTrapAtOffset = [&](uint64_t Offset) { MCInst TrapInstr; BC.MIB->createTrap(TrapInstr); addInstruction(Offset, std::move(TrapInstr)); }; addTrapAtOffset(0); for (auto &KV : getLabels()) { if (getSecondaryEntryPointSymbol(KV.second)) { addTrapAtOffset(KV.first); } } TrapsOnEntry = true; } void BinaryFunction::duplicateConstantIslands() { for (auto BB : layout()) { if (!BB->isCold()) continue; for (auto &Inst : *BB) { int OpNum = 0; for (auto &Operand : Inst) { if (!Operand.isExpr()) { ++OpNum; continue; } auto *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; } } } } namespace { #ifndef MAX_PATH #define MAX_PATH 255 #endif 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); if (opts::Verbosity >= 1) { errs() << "BOLT-WARNING: Filename \"" << Filename << Annotation << Suffix << "\" exceeds the " << MAX_PATH << " size limit, truncating.\n"; } Filename.resize(MAX_PATH - (Suffix.size() + Annotation.size())); } Filename += Annotation; Filename += Suffix; return Filename; } std::string formatEscapes(const std::string& Str) { std::string Result; for (unsigned I = 0; I < Str.size(); ++I) { auto 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 << "strict digraph \"" << getPrintName() << "\" {\n"; uint64_t Offset = Address; for (auto *BB : BasicBlocks) { auto LayoutPos = std::find(BasicBlocksLayout.begin(), BasicBlocksLayout.end(), BB); unsigned Layout = LayoutPos - BasicBlocksLayout.begin(); const char* ColdStr = BB->isCold() ? " (cold)" : ""; 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->ExecutionCount != BinaryBasicBlock::COUNT_NO_PROFILE ? BB->ExecutionCount : 0), BB->getOffset(), getIndex(BB), Layout, BB->getCFIState()); OS << format("\"%s\" [shape=box]\n", BB->getName().data()); if (opts::DotToolTipCode) { std::string Str; raw_string_ostream CS(Str); Offset = BC.printInstructions(CS, BB->begin(), BB->end(), Offset, this); const auto Code = formatEscapes(CS.str()); OS << format("\"%s\" [tooltip=\"%s\"]\n", BB->getName().data(), Code.c_str()); } // 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 auto *LastInstr = BB->getLastNonPseudoInstr(); const bool IsJumpTable = LastInstr && BC.MIB->getJumpTable(*LastInstr); auto BI = BB->branch_info_begin(); for (auto *Succ : BB->successors()) { std::string Branch; if (Success) { if (Succ == BB->getConditionalSuccessor(true)) { Branch = CondBranch ? BC.InstPrinter->getOpcodeName(CondBranch->getOpcode()) : "TB"; } else if (Succ == BB->getConditionalSuccessor(false)) { Branch = UncondBranch ? 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 (auto *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 (auto EC = sys::fs::createTemporaryFile("bolt-cfg", "dot", Filename)) { errs() << "BOLT-ERROR: " << EC.message() << ", unable to create " << " bolt-cfg-XXXXX.dot temporary file.\n"; return; } dumpGraphToFile(Filename.str()); if (DisplayGraph(Filename)) { errs() << "BOLT-ERROR: Can't display " << Filename << " with graphviz.\n"; } if (auto EC = sys::fs::remove(Filename)) { errs() << "BOLT-WARNING: " << EC.message() << ", failed to remove " << Filename << "\n"; } } void BinaryFunction::dumpGraphForPass(std::string Annotation) const { auto Filename = constructFilename(getPrintName(), Annotation, ".dot"); outs() << "BOLT-DEBUG: 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::F_None); if (EC) { if (opts::Verbosity >= 1) { errs() << "BOLT-WARNING: " << EC.message() << ", unable to open " << Filename << " for output.\n"; } return; } dumpGraph(of); } bool BinaryFunction::validateCFG() const { bool Valid = true; for (auto *BB : BasicBlocks) { Valid &= BB->validateSuccessorInvariants(); } if (!Valid) return Valid; // Make sure all blocks in CFG are valid. auto validateBlock = [this](const BinaryBasicBlock *BB, StringRef Desc) { if (!BB->isValid()) { errs() << "BOLT-ERROR: deleted " << Desc << " " << BB->getName() << " detected in:\n"; this->dump(); return false; } return true; }; for (const auto *BB : BasicBlocks) { if (!validateBlock(BB, "block")) return false; for (const auto *PredBB : BB->predecessors()) if (!validateBlock(PredBB, "predecessor")) return false; for (const auto *SuccBB: BB->successors()) if (!validateBlock(SuccBB, "successor")) return false; for (const auto *LP: BB->landing_pads()) if (!validateBlock(LP, "landing pad")) return false; for (const auto *Thrower: BB->throwers()) if (!validateBlock(Thrower, "thrower")) return false; } for (const auto *BB : BasicBlocks) { std::unordered_set BBLandingPads; for (const auto *LP : BB->landing_pads()) { if (BBLandingPads.count(LP)) { 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 auto *Thrower : BB->throwers()) { if (BBThrowers.count(Thrower)) { errs() << "BOLT-ERROR: duplicate thrower detected in" << BB->getName() << " in function " << *this << '\n'; return false; } BBThrowers.insert(Thrower); } for (const auto *LPBlock : BB->landing_pads()) { if (std::find(LPBlock->throw_begin(), LPBlock->throw_end(), BB) == LPBlock->throw_end()) { 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 auto *Thrower : BB->throwers()) { if (std::find(Thrower->lp_begin(), Thrower->lp_end(), BB) == Thrower->lp_end()) { errs() << "BOLT-ERROR: inconsistent thrower detected in " << *this << ": " << BB->getName() << " is in Throwers list but not in " << Thrower->getName() << " LandingPads\n"; return false; } } } return Valid; } void BinaryFunction::fixBranches() { auto &MIB = BC.MIB; auto *Ctx = BC.Ctx.get(); for (unsigned I = 0, E = BasicBlocksLayout.size(); I != E; ++I) { BinaryBasicBlock *BB = BasicBlocksLayout[I]; 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 *NextBB = nullptr; if (I + 1 != E && BB->isCold() == BasicBlocksLayout[I + 1]->isCold()) NextBB = BasicBlocksLayout[I + 1]; 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 auto *TSuccessor = BB->getConditionalSuccessor(true); const auto *FSuccessor = BB->getConditionalSuccessor(false); if (NextBB && NextBB == TSuccessor) { std::swap(TSuccessor, FSuccessor); { auto L = BC.scopeLock(); MIB->reverseBranchCondition(*CondBranch, TSuccessor->getLabel(), Ctx); } BB->swapConditionalSuccessors(); } else { auto L = BC.scopeLock(); MIB->replaceBranchTarget(*CondBranch, TSuccessor->getLabel(), Ctx); } if (TSuccessor == FSuccessor) { BB->removeDuplicateConditionalSuccessor(CondBranch); } if (!NextBB || (NextBB != TSuccessor && NextBB != FSuccessor)) { // If one of the branches is guaranteed to be "long" while the other // could be "short", then prioritize short for "taken". This will // generate a sequence 1 byte shorter on x86. if (BC.isX86() && TSuccessor->isCold() != FSuccessor->isCold() && BB->isCold() != TSuccessor->isCold()) { std::swap(TSuccessor, FSuccessor); { auto L = BC.scopeLock(); MIB->reverseBranchCondition(*CondBranch, TSuccessor->getLabel(), Ctx); } BB->swapConditionalSuccessors(); } 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 (auto BB : BasicBlocks) { for (auto II = BB->begin(); II != BB->end(); ) { auto &Instr = *II; if (BC.MIB->isCFI(Instr)) { auto 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, AllocId); } ++II; } } } void BinaryFunction::postProcessBranches() { if (!isSimple()) return; for (auto *BB : BasicBlocksLayout) { 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())); 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()) { 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)) { 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 (auto *EntryBD = BC.getBinaryDataAtAddress(EntryPointAddress)) { EntrySymbol = EntryBD->getSymbol(); } else { EntrySymbol = BC.Ctx->getOrCreateSymbol( "__ENTRY_0x" + Twine::utohexstr(Offset) + "_" + getOneName()); } SecondaryEntryPoints[LocalSymbol] = EntrySymbol; BC.setSymbolToFunctionMap(EntrySymbol, this); // 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. if (!BC.HasRelocations) { if (opts::Verbosity >= 1) { outs() << "BOLT-INFO: function " << *this << " has an internal address that is a potential target of a " << " reference from another function. Skipping the function.\n"; } setSimple(false); } 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(); auto *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; } const MCSymbol *BinaryFunction::getSymbolForEntryID(uint64_t EntryID) const { if (EntryID == 0) return getSymbol(); if (!isMultiEntry()) return nullptr; uint64_t NumEntries = 0; if (hasCFG()) { for (auto *BB : BasicBlocks) { auto *EntrySymbol = getSecondaryEntryPointSymbol(*BB); if (!EntrySymbol) continue; if (NumEntries == EntryID) return EntrySymbol; ++NumEntries; } } else { for (auto &KV : Labels) { auto *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 auto *FunctionSymbol : getSymbols()) if (FunctionSymbol == Symbol) return 0; // Check all secondary entries available as either basic blocks or lables. uint64_t NumEntries = 0; for (const auto *BB : BasicBlocks) { auto *EntrySymbol = getSecondaryEntryPointSymbol(*BB); if (!EntrySymbol) continue; if (EntrySymbol == Symbol) return NumEntries; ++NumEntries; } NumEntries = 0; for (auto &KV : Labels) { auto *EntrySymbol = getSecondaryEntryPointSymbol(KV.second); if (!EntrySymbol) continue; if (EntrySymbol == Symbol) return NumEntries; ++NumEntries; } llvm_unreachable("symbol not found"); } BinaryFunction::BasicBlockOrderType BinaryFunction::dfs() const { BasicBlockOrderType DFS; unsigned Index = 0; std::stack Stack; // Push entry points to the stack in reverse order. // // NB: we rely on the original order of entries to match. for (auto BBI = layout_rbegin(); BBI != layout_rend(); ++BBI) { auto *BB = *BBI; if (isEntryPoint(*BB)) Stack.push(BB); BB->setLayoutIndex(BinaryBasicBlock::InvalidIndex); } while (!Stack.empty()) { auto *BB = Stack.top(); Stack.pop(); if (BB->getLayoutIndex() != BinaryBasicBlock::InvalidIndex) continue; BB->setLayoutIndex(Index++); DFS.push_back(BB); for (auto *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->getCanonicalBranchOpcode(CondBranch->getOpcode()) == CondBranch->getOpcode()) { Stack.push(BB->getConditionalSuccessor(true)); Stack.push(BB->getConditionalSuccessor(false)); } else { Stack.push(BB->getConditionalSuccessor(false)); Stack.push(BB->getConditionalSuccessor(true)); } } else { for (auto *SuccBB : BB->successors()) { Stack.push(SuccBB); } } } return DFS; } size_t BinaryFunction::computeHash(bool UseDFS, OperandHashFuncTy OperandHashFunc) const { if (size() == 0) return 0; assert(hasCFG() && "function is expected to have CFG"); const auto &Order = UseDFS ? dfs() : BasicBlocksLayout; // 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 auto *BB : Order) { for (const auto &Inst : *BB) { unsigned Opcode = Inst.getOpcode(); if (BC.MII->get(Opcode).isPseudo()) continue; // Ignore unconditional jumps since we check CFG consistency by processing // basic blocks in order and do not rely on branches to be in-sync with // CFG. Note that we still use condition code of conditional jumps. if (BC.MIB->isUnconditionalBranch(Inst)) continue; if (Opcode == 0) HashString.push_back(0); while (Opcode) { uint8_t LSB = Opcode & 0xff; HashString.push_back(LSB); Opcode = Opcode >> 8; } for (int I = 0, E = MCPlus::getNumPrimeOperands(Inst); I != E; ++I) { HashString.append(OperandHashFunc(Inst.getOperand(I))); } } } return Hash = std::hash{}(HashString); } void BinaryFunction::insertBasicBlocks( BinaryBasicBlock *Start, std::vector> &&NewBBs, const bool UpdateLayout, const bool UpdateCFIState, const bool RecomputeLandingPads) { const auto StartIndex = Start ? getIndex(Start) : -1; const auto NumNewBlocks = NewBBs.size(); BasicBlocks.insert(BasicBlocks.begin() + (StartIndex + 1), NumNewBlocks, nullptr); auto I = StartIndex + 1; for (auto &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 auto StartIndex = getIndex(&*StartBB); const auto NumNewBlocks = NewBBs.size(); BasicBlocks.insert(BasicBlocks.begin() + StartIndex + 1, NumNewBlocks, nullptr); auto RetIter = BasicBlocks.begin() + StartIndex + 1; auto I = StartIndex + 1; for (auto &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 (auto I = StartIndex; I < BasicBlocks.size(); ++I) { BasicBlocks[I]->Index = I; } } void BinaryFunction::updateCFIState(BinaryBasicBlock *Start, const unsigned NumNewBlocks) { const auto CFIState = Start->getCFIStateAtExit(); const auto StartIndex = getIndex(Start) + 1; for (unsigned I = 0; I < NumNewBlocks; ++I) { BasicBlocks[StartIndex + I]->setCFIState(CFIState); } } void BinaryFunction::updateLayout(BinaryBasicBlock *Start, const unsigned NumNewBlocks) { // If start not provided insert new blocks at the beginning if (!Start) { BasicBlocksLayout.insert(layout_begin(), BasicBlocks.begin(), BasicBlocks.begin() + NumNewBlocks); updateLayoutIndices(); return; } // Insert new blocks in the layout immediately after Start. auto Pos = std::find(layout_begin(), layout_end(), Start); assert(Pos != layout_end()); auto Begin = &BasicBlocks[getIndex(Start) + 1]; auto End = &BasicBlocks[getIndex(Start) + NumNewBlocks + 1]; BasicBlocksLayout.insert(Pos + 1, Begin, End); updateLayoutIndices(); } bool BinaryFunction::checkForAmbiguousJumpTables() { SmallSet JumpTables; for (auto &BB : BasicBlocks) { for (auto &Inst : *BB) { if (!BC.MIB->isIndirectBranch(Inst)) continue; auto 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 (auto &BB : BasicBlocks) { for (auto &Inst : *BB) { if (!BC.MIB->isIndirectBranch(Inst)) continue; auto *JT = getJumpTable(Inst); if (!JT) continue; auto Iter = JumpTables.find(JT); if (Iter == JumpTables.end()) { JumpTables.insert(JT); 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 uint64_t Scale; const MCSymbol *Target; MCInst *JTLoadInst = &Inst; // Try a standard indirect jump matcher, scale 8 auto IndJmpMatcher = BC.MIB->matchIndJmp( BC.MIB->matchReg(), BC.MIB->matchImm(Scale), BC.MIB->matchReg(), /*Offset=*/BC.MIB->matchSymbol(Target)); if (!BC.MIB->hasPCRelOperand(Inst) || !IndJmpMatcher->match( *BC.MRI, *BC.MIB, MutableArrayRef(&*BB->begin(), &Inst + 1), -1) || Scale != 8) { // Standard 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 MCPhysReg BaseReg1; MCPhysReg BaseReg2; uint64_t Offset; auto 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)))); auto LEAMatcherOwner = BC.MIB->matchLoadAddr(BC.MIB->matchSymbol(Target)); auto LEAMatcher = LEAMatcherOwner.get(); auto 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 JTLoadInst = &*LEAMatcher->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) { auto *Instr = BB->getLastNonPseudoInstr(); if (!Instr || !BC.MIB->isIndirectBranch(*Instr)) return false; auto JTAddress = BC.MIB->getJumpTable(*Instr); assert(JTAddress && "Invalid jump table address"); auto *JT = getJumpTableContainingAddress(JTAddress); assert(JT && "No jump table structure for this indirect branch"); bool Patched = JT->replaceDestination(JTAddress, OldDest->getLabel(), NewDest->getLabel()); 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->createTempSymbol("SplitEdge", true); } // 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) auto NewBB = createBasicBlock(From->getInputOffset(), Tmp); auto 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) { auto 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; auto *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::isDataMarker(const SymbolRef &Symbol, uint64_t SymbolSize) const { // For aarch64, the ABI defines mapping symbols so we identify data in the // code section (see IHI0056B). $d identifies a symbol starting data contents. if (BC.isAArch64() && Symbol.getType() && cantFail(Symbol.getType()) == SymbolRef::ST_Unknown && SymbolSize == 0 && Symbol.getName() && cantFail(Symbol.getName()) == "$d") return true; return false; } bool BinaryFunction::isCodeMarker(const SymbolRef &Symbol, uint64_t SymbolSize) const { // For aarch64, the ABI defines mapping symbols so we identify data in the // code section (see IHI0056B). $x identifies a symbol starting code or the // end of a data chunk inside code. if (BC.isAArch64() && Symbol.getType() && cantFail(Symbol.getType()) == SymbolRef::ST_Unknown && SymbolSize == 0 && Symbol.getName() && cantFail(Symbol.getName()) == "$x") return true; return false; } 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 (!getSection().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 (isDataMarker(Symbol, SymbolSize) || isCodeMarker(Symbol, SymbolSize)) 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 (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 (auto &BB : layout()) BB->adjustExecutionCount(AdjustmentRatio); ExecutionCount -= Count; } BinaryFunction::~BinaryFunction() { for (auto BB : BasicBlocks) { delete BB; } for (auto BB : DeletedBasicBlocks) { delete BB; } } void BinaryFunction::calculateLoopInfo() { // Discover loops. BinaryDominatorTree DomTree; DomTree.recalculate(*this); BLI.reset(new BinaryLoopInfo()); BLI->analyze(DomTree); // 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 MCAsmLayout &Layout) { if (!isEmitted()) { assert(!isInjected() && "injected function should be emitted"); setOutputAddress(getAddress()); setOutputSize(getSize()); return; } const auto BaseAddress = getCodeSection()->getOutputAddress(); auto ColdSection = getColdCodeSection(); const auto ColdBaseAddress = isSplit() ? ColdSection->getOutputAddress() : 0; if (BC.HasRelocations || isInjected()) { const auto StartOffset = Layout.getSymbolOffset(*getSymbol()); const auto EndOffset = Layout.getSymbolOffset(*getFunctionEndLabel()); setOutputAddress(BaseAddress + StartOffset); setOutputSize(EndOffset - StartOffset); if (hasConstantIsland()) { const auto DataOffset = Layout.getSymbolOffset(*getFunctionConstantIslandLabel()); setOutputDataAddress(BaseAddress + DataOffset); } if (isSplit()) { const auto *ColdStartSymbol = getColdSymbol(); assert(ColdStartSymbol && ColdStartSymbol->isDefined() && "split function should have defined cold symbol"); const auto *ColdEndSymbol = getFunctionColdEndLabel(); assert(ColdEndSymbol && ColdEndSymbol->isDefined() && "split function should have defined cold end symbol"); const auto ColdStartOffset = Layout.getSymbolOffset(*ColdStartSymbol); const auto ColdEndOffset = Layout.getSymbolOffset(*ColdEndSymbol); cold().setAddress(ColdBaseAddress + ColdStartOffset); cold().setImageSize(ColdEndOffset - ColdStartOffset); if (hasConstantIsland()) { const auto DataOffset = Layout.getSymbolOffset( *getFunctionColdConstantIslandLabel()); setOutputColdDataAddress(ColdBaseAddress + DataOffset); } } } else { setOutputAddress(getAddress()); setOutputSize( Layout.getSymbolOffset(*getFunctionEndLabel())); } // 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 (!opts::UpdateDebugSections && !isMultiEntry() && !requiresAddressTranslation()) return; // Output ranges should match the input if the body hasn't changed. if (!isSimple() && !BC.HasRelocations) return; // AArch64 may have functions that only contains a constant island (no code). if (layout_begin() == layout_end()) return; BinaryBasicBlock *PrevBB = nullptr; for (auto BBI = layout_begin(), BBE = layout_end(); BBI != BBE; ++BBI) { auto *BB = *BBI; assert(BB->getLabel()->isDefined() && "symbol should be defined"); const auto BBBaseAddress = BB->isCold() ? ColdBaseAddress : BaseAddress; if (!BC.HasRelocations) { if (BB->isCold()) { assert(BBBaseAddress == cold().getAddress()); } else { assert(BBBaseAddress == getOutputAddress()); } } const auto BBOffset = Layout.getSymbolOffset(*BB->getLabel()); const auto BBAddress = BBBaseAddress + BBOffset; BB->setOutputStartAddress(BBAddress); if (PrevBB) { auto PrevBBEndAddress = BBAddress; if (BB->isCold() != PrevBB->isCold()) { PrevBBEndAddress = getOutputAddress() + getOutputSize(); } PrevBB->setOutputEndAddress(PrevBBEndAddress); } PrevBB = BB; BB->updateOutputValues(Layout); } PrevBB->setOutputEndAddress(PrevBB->isCold() ? cold().getAddress() + cold().getImageSize() : getOutputAddress() + getOutputSize()); } DebugAddressRangesVector BinaryFunction::getOutputAddressRanges() const { DebugAddressRangesVector OutputRanges; if (IsFragment) return OutputRanges; OutputRanges.emplace_back(getOutputAddress(), getOutputAddress() + getOutputSize()); if (isSplit()) { assert(isEmitted() && "split function should be emitted"); OutputRanges.emplace_back(cold().getAddress(), cold().getAddress() + cold().getImageSize()); } if (isSimple()) return OutputRanges; for (auto *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 the function hasn't changed return the same address. if (!isEmitted() && !BC.HasRelocations) return Address; if (Address < getAddress()) return 0; // Check if the address is associated with an instruction that is tracked // by address translation. auto KV = InputOffsetToAddressMap.find(Address - getAddress()); if (KV != InputOffsetToAddressMap.end()) { return KV->second; } // FIXME: #18950828 - we rely on relative offsets inside basic blocks to stay // intact. Instead we can use pseudo instructions and/or annotations. const auto Offset = Address - getAddress(); const auto *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::translateInputToOutputRanges( const DWARFAddressRangesVector &InputRanges) const { DebugAddressRangesVector OutputRanges; // If the function hasn't changed return the same ranges. if (!isEmitted() && !BC.HasRelocations) { OutputRanges.resize(InputRanges.size()); std::transform(InputRanges.begin(), InputRanges.end(), OutputRanges.begin(), [](const DWARFAddressRange &Range) { return DebugAddressRange(Range.LowPC, Range.HighPC); }); return OutputRanges; } // Even though we will merge ranges in a post-processing pass, we attempt to // merge them in a main processing loop as it improves the processing time. uint64_t PrevEndAddress = 0; for (const auto &Range : InputRanges) { if (!containsAddress(Range.LowPC)) { DEBUG(dbgs() << "BOLT-DEBUG: invalid debug address range detected for " << *this << " : [0x" << Twine::utohexstr(Range.LowPC) << ", 0x" << Twine::utohexstr(Range.HighPC) << "]\n"); PrevEndAddress = 0; continue; } auto InputOffset = Range.LowPC - getAddress(); const auto InputEndOffset = std::min(Range.HighPC - getAddress(), getSize()); auto BBI = std::upper_bound(BasicBlockOffsets.begin(), BasicBlockOffsets.end(), BasicBlockOffset(InputOffset, nullptr), CompareBasicBlockOffsets()); --BBI; do { const auto *BB = BBI->second; if (InputOffset < BB->getOffset() || InputOffset >= BB->getEndOffset()) { DEBUG(dbgs() << "BOLT-DEBUG: invalid debug address range detected for " << *this << " : [0x" << Twine::utohexstr(Range.LowPC) << ", 0x" << Twine::utohexstr(Range.HighPC) << "]\n"); PrevEndAddress = 0; break; } // Skip the range if the block was deleted. if (const auto OutputStart = BB->getOutputAddressRange().first) { const auto StartAddress = OutputStart + InputOffset - BB->getOffset(); auto EndAddress = BB->getOutputAddressRange().second; if (InputEndOffset < BB->getEndOffset()) EndAddress = StartAddress + InputEndOffset - InputOffset; if (StartAddress == PrevEndAddress) { OutputRanges.back().HighPC = std::max(OutputRanges.back().HighPC, EndAddress); } else { OutputRanges.emplace_back(StartAddress, std::max(StartAddress, EndAddress)); } PrevEndAddress = OutputRanges.back().HighPC; } InputOffset = BB->getEndOffset(); ++BBI; } while (InputOffset < InputEndOffset); } // Post-processing pass to sort and merge ranges. std::sort(OutputRanges.begin(), OutputRanges.end()); DebugAddressRangesVector MergedRanges; PrevEndAddress = 0; for (const auto &Range : OutputRanges) { if (Range.LowPC <= PrevEndAddress) { MergedRanges.back().HighPC = std::max(MergedRanges.back().HighPC, Range.HighPC); } else { MergedRanges.emplace_back(Range.LowPC, Range.HighPC); } PrevEndAddress = MergedRanges.back().HighPC; } return MergedRanges; } 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) { auto *BB = getBasicBlockContainingOffset(Offset); if (!BB) return nullptr; for (auto &Inst : *BB) { constexpr auto InvalidOffset = std::numeric_limits::max(); if (Offset == BC.MIB->getAnnotationWithDefault(Inst, "Offset", InvalidOffset)) return &Inst; } return nullptr; } else { llvm_unreachable("invalid CFG state to use getInstructionAtOffset()"); } } std::set BinaryFunction::dataUses(bool OnlyHot) const { std::set Uses; for (auto *BB : BasicBlocks) { if (OnlyHot && BB->isCold()) continue; for (const auto &Inst : *BB) { if (auto Mem = BC.MIB->tryGetAnnotationAs(Inst, "MemDataOffset")) { for (auto &MI : getMemData()->getMemInfoRange(Mem.get())) { if (auto *BD = MI.Addr.IsSymbol ? BC.getBinaryDataByName(MI.Addr.Name) : BC.getBinaryDataContainingAddress(MI.Addr.Offset)) { Uses.insert(BD); } } } } } return Uses; } DWARFDebugLoc::LocationList BinaryFunction::translateInputToOutputLocationList( DWARFDebugLoc::LocationList InputLL) const { // If the function hasn't changed - there's nothing to update. if (!isEmitted() && !BC.HasRelocations) { return InputLL; } uint64_t PrevEndAddress = 0; SmallVectorImpl *PrevLoc = nullptr; DWARFDebugLoc::LocationList OutputLL; for (const auto &Entry : InputLL.Entries) { const auto Start = Entry.Begin; const auto End = Entry.End; if (!containsAddress(Start)) { DEBUG(dbgs() << "BOLT-DEBUG: invalid debug address range detected for " << *this << " : [0x" << Twine::utohexstr(Start) << ", 0x" << Twine::utohexstr(End) << "]\n"); continue; } auto InputOffset = Start - getAddress(); const auto InputEndOffset = std::min(End - getAddress(), getSize()); auto BBI = std::upper_bound(BasicBlockOffsets.begin(), BasicBlockOffsets.end(), BasicBlockOffset(InputOffset, nullptr), CompareBasicBlockOffsets()); --BBI; do { const auto *BB = BBI->second; if (InputOffset < BB->getOffset() || InputOffset >= BB->getEndOffset()) { DEBUG(dbgs() << "BOLT-DEBUG: invalid debug address range detected for " << *this << " : [0x" << Twine::utohexstr(Start) << ", 0x" << Twine::utohexstr(End) << "]\n"); PrevEndAddress = 0; break; } // Skip the range if the block was deleted. if (const auto OutputStart = BB->getOutputAddressRange().first) { const auto StartAddress = OutputStart + InputOffset - BB->getOffset(); auto EndAddress = BB->getOutputAddressRange().second; if (InputEndOffset < BB->getEndOffset()) EndAddress = StartAddress + InputEndOffset - InputOffset; if (StartAddress == PrevEndAddress && Entry.Loc == *PrevLoc) { OutputLL.Entries.back().End = std::max(OutputLL.Entries.back().End, EndAddress); } else { OutputLL.Entries.emplace_back( DWARFDebugLoc::Entry{StartAddress, std::max(StartAddress, EndAddress), Entry.Loc}); } PrevEndAddress = OutputLL.Entries.back().End; PrevLoc = &OutputLL.Entries.back().Loc; } ++BBI; InputOffset = BB->getEndOffset(); } while (InputOffset < InputEndOffset); } // Sort and merge adjacent entries with identical location. std::stable_sort(OutputLL.Entries.begin(), OutputLL.Entries.end(), [] (const DWARFDebugLoc::Entry &A, const DWARFDebugLoc::Entry &B) { return A.Begin < B.Begin; }); DWARFDebugLoc::LocationList MergedLL; PrevEndAddress = 0; PrevLoc = nullptr; for (const auto &Entry : OutputLL.Entries) { if (Entry.Begin <= PrevEndAddress && *PrevLoc == Entry.Loc) { MergedLL.Entries.back().End = std::max(Entry.End, MergedLL.Entries.back().End); } else { const auto Begin = std::max(Entry.Begin, PrevEndAddress); const auto End = std::max(Begin, Entry.End); MergedLL.Entries.emplace_back(DWARFDebugLoc::Entry{Begin, End, Entry.Loc}); } PrevEndAddress = MergedLL.Entries.back().End; PrevLoc = &MergedLL.Entries.back().Loc; } return MergedLL; } void BinaryFunction::printLoopInfo(raw_ostream &OS) const { OS << "Loop Info for Function \"" << *this << "\""; if (hasValidProfile()) { OS << " (count: " << getExecutionCount() << ")"; } OS << "\n"; std::stack St; for (auto I = BLI->begin(), E = BLI->end(); I != E; ++I) { St.push(*I); } while (!St.empty()) { BinaryLoop *L = St.top(); St.pop(); for (BinaryLoop::iterator I = L->begin(), E = L->end(); I != E; ++I) { St.push(*I); } if (!hasValidProfile()) continue; OS << (L->getLoopDepth() > 1 ? "Nested" : "Outer") << " loop header: " << L->getHeader()->getName(); OS << "\n"; OS << "Loop basic blocks: "; auto Sep = ""; for (auto BI = L->block_begin(), BE = L->block_end(); BI != BE; ++BI) { OS << Sep << (*BI)->getName(); Sep = ", "; } 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 (BasicBlocks.size() != 1) return false; auto &BB = **BasicBlocks.begin(); if (BB.size() != 3) return false; for (auto &Inst : BB) { if (!BC.MIB->hasAnnotation(Inst, "AArch64Veneer")) return false; } return true; } } // namespace bolt } // namespace llvm