1 //===- bolt/Core/BinaryFunction.cpp - Low-level function ------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements the BinaryFunction class. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "bolt/Core/BinaryFunction.h" 14 #include "bolt/Core/BinaryBasicBlock.h" 15 #include "bolt/Core/DynoStats.h" 16 #include "bolt/Core/HashUtilities.h" 17 #include "bolt/Core/MCPlusBuilder.h" 18 #include "bolt/Utils/NameResolver.h" 19 #include "bolt/Utils/NameShortener.h" 20 #include "bolt/Utils/Utils.h" 21 #include "llvm/ADT/STLExtras.h" 22 #include "llvm/ADT/SmallSet.h" 23 #include "llvm/ADT/StringExtras.h" 24 #include "llvm/ADT/StringRef.h" 25 #include "llvm/Demangle/Demangle.h" 26 #include "llvm/MC/MCAsmInfo.h" 27 #include "llvm/MC/MCContext.h" 28 #include "llvm/MC/MCDisassembler/MCDisassembler.h" 29 #include "llvm/MC/MCExpr.h" 30 #include "llvm/MC/MCInst.h" 31 #include "llvm/MC/MCInstPrinter.h" 32 #include "llvm/MC/MCRegisterInfo.h" 33 #include "llvm/MC/MCSymbol.h" 34 #include "llvm/Object/ObjectFile.h" 35 #include "llvm/Support/CommandLine.h" 36 #include "llvm/Support/Debug.h" 37 #include "llvm/Support/GenericDomTreeConstruction.h" 38 #include "llvm/Support/GenericLoopInfoImpl.h" 39 #include "llvm/Support/GraphWriter.h" 40 #include "llvm/Support/LEB128.h" 41 #include "llvm/Support/Regex.h" 42 #include "llvm/Support/Timer.h" 43 #include "llvm/Support/raw_ostream.h" 44 #include "llvm/Support/xxhash.h" 45 #include <functional> 46 #include <limits> 47 #include <numeric> 48 #include <stack> 49 #include <string> 50 51 #define DEBUG_TYPE "bolt" 52 53 using namespace llvm; 54 using namespace bolt; 55 56 namespace opts { 57 58 extern cl::OptionCategory BoltCategory; 59 extern cl::OptionCategory BoltOptCategory; 60 61 extern cl::opt<bool> EnableBAT; 62 extern cl::opt<bool> Instrument; 63 extern cl::opt<bool> StrictMode; 64 extern cl::opt<bool> UpdateDebugSections; 65 extern cl::opt<unsigned> Verbosity; 66 67 extern bool processAllFunctions(); 68 69 cl::opt<bool> CheckEncoding( 70 "check-encoding", 71 cl::desc("perform verification of LLVM instruction encoding/decoding. " 72 "Every instruction in the input is decoded and re-encoded. " 73 "If the resulting bytes do not match the input, a warning message " 74 "is printed."), 75 cl::Hidden, cl::cat(BoltCategory)); 76 77 static cl::opt<bool> DotToolTipCode( 78 "dot-tooltip-code", 79 cl::desc("add basic block instructions as tool tips on nodes"), cl::Hidden, 80 cl::cat(BoltCategory)); 81 82 cl::opt<JumpTableSupportLevel> 83 JumpTables("jump-tables", 84 cl::desc("jump tables support (default=basic)"), 85 cl::init(JTS_BASIC), 86 cl::values( 87 clEnumValN(JTS_NONE, "none", 88 "do not optimize functions with jump tables"), 89 clEnumValN(JTS_BASIC, "basic", 90 "optimize functions with jump tables"), 91 clEnumValN(JTS_MOVE, "move", 92 "move jump tables to a separate section"), 93 clEnumValN(JTS_SPLIT, "split", 94 "split jump tables section into hot and cold based on " 95 "function execution frequency"), 96 clEnumValN(JTS_AGGRESSIVE, "aggressive", 97 "aggressively split jump tables section based on usage " 98 "of the tables")), 99 cl::ZeroOrMore, 100 cl::cat(BoltOptCategory)); 101 102 static cl::opt<bool> NoScan( 103 "no-scan", 104 cl::desc( 105 "do not scan cold functions for external references (may result in " 106 "slower binary)"), 107 cl::Hidden, cl::cat(BoltOptCategory)); 108 109 cl::opt<bool> 110 PreserveBlocksAlignment("preserve-blocks-alignment", 111 cl::desc("try to preserve basic block alignment"), 112 cl::cat(BoltOptCategory)); 113 114 static cl::opt<bool> PrintOutputAddressRange( 115 "print-output-address-range", 116 cl::desc( 117 "print output address range for each basic block in the function when" 118 "BinaryFunction::print is called"), 119 cl::Hidden, cl::cat(BoltOptCategory)); 120 121 cl::opt<bool> 122 PrintDynoStats("dyno-stats", 123 cl::desc("print execution info based on profile"), 124 cl::cat(BoltCategory)); 125 126 static cl::opt<bool> 127 PrintDynoStatsOnly("print-dyno-stats-only", 128 cl::desc("while printing functions output dyno-stats and skip instructions"), 129 cl::init(false), 130 cl::Hidden, 131 cl::cat(BoltCategory)); 132 133 static cl::list<std::string> 134 PrintOnly("print-only", 135 cl::CommaSeparated, 136 cl::desc("list of functions to print"), 137 cl::value_desc("func1,func2,func3,..."), 138 cl::Hidden, 139 cl::cat(BoltCategory)); 140 141 cl::opt<bool> 142 TimeBuild("time-build", 143 cl::desc("print time spent constructing binary functions"), 144 cl::Hidden, cl::cat(BoltCategory)); 145 146 cl::opt<bool> 147 TrapOnAVX512("trap-avx512", 148 cl::desc("in relocation mode trap upon entry to any function that uses " 149 "AVX-512 instructions"), 150 cl::init(false), 151 cl::ZeroOrMore, 152 cl::Hidden, 153 cl::cat(BoltCategory)); 154 155 bool shouldPrint(const BinaryFunction &Function) { 156 if (Function.isIgnored()) 157 return false; 158 159 if (PrintOnly.empty()) 160 return true; 161 162 for (std::string &Name : opts::PrintOnly) { 163 if (Function.hasNameRegex(Name)) { 164 return true; 165 } 166 } 167 168 return false; 169 } 170 171 } // namespace opts 172 173 namespace llvm { 174 namespace bolt { 175 176 template <typename R> static bool emptyRange(const R &Range) { 177 return Range.begin() == Range.end(); 178 } 179 180 /// Gets debug line information for the instruction located at the given 181 /// address in the original binary. The SMLoc's pointer is used 182 /// to point to this information, which is represented by a 183 /// DebugLineTableRowRef. The returned pointer is null if no debug line 184 /// information for this instruction was found. 185 static SMLoc findDebugLineInformationForInstructionAt( 186 uint64_t Address, DWARFUnit *Unit, 187 const DWARFDebugLine::LineTable *LineTable) { 188 // We use the pointer in SMLoc to store an instance of DebugLineTableRowRef, 189 // which occupies 64 bits. Thus, we can only proceed if the struct fits into 190 // the pointer itself. 191 static_assert( 192 sizeof(decltype(SMLoc().getPointer())) >= sizeof(DebugLineTableRowRef), 193 "Cannot fit instruction debug line information into SMLoc's pointer"); 194 195 SMLoc NullResult = DebugLineTableRowRef::NULL_ROW.toSMLoc(); 196 uint32_t RowIndex = LineTable->lookupAddress( 197 {Address, object::SectionedAddress::UndefSection}); 198 if (RowIndex == LineTable->UnknownRowIndex) 199 return NullResult; 200 201 assert(RowIndex < LineTable->Rows.size() && 202 "Line Table lookup returned invalid index."); 203 204 decltype(SMLoc().getPointer()) Ptr; 205 DebugLineTableRowRef *InstructionLocation = 206 reinterpret_cast<DebugLineTableRowRef *>(&Ptr); 207 208 InstructionLocation->DwCompileUnitIndex = Unit->getOffset(); 209 InstructionLocation->RowIndex = RowIndex + 1; 210 211 return SMLoc::getFromPointer(Ptr); 212 } 213 214 static std::string buildSectionName(StringRef Prefix, StringRef Name, 215 const BinaryContext &BC) { 216 if (BC.isELF()) 217 return (Prefix + Name).str(); 218 static NameShortener NS; 219 return (Prefix + Twine(NS.getID(Name))).str(); 220 } 221 222 static raw_ostream &operator<<(raw_ostream &OS, 223 const BinaryFunction::State State) { 224 switch (State) { 225 case BinaryFunction::State::Empty: OS << "empty"; break; 226 case BinaryFunction::State::Disassembled: OS << "disassembled"; break; 227 case BinaryFunction::State::CFG: OS << "CFG constructed"; break; 228 case BinaryFunction::State::CFG_Finalized: OS << "CFG finalized"; break; 229 case BinaryFunction::State::EmittedCFG: OS << "emitted with CFG"; break; 230 case BinaryFunction::State::Emitted: OS << "emitted"; break; 231 } 232 233 return OS; 234 } 235 236 std::string BinaryFunction::buildCodeSectionName(StringRef Name, 237 const BinaryContext &BC) { 238 return buildSectionName(BC.isELF() ? ".local.text." : ".l.text.", Name, BC); 239 } 240 241 std::string BinaryFunction::buildColdCodeSectionName(StringRef Name, 242 const BinaryContext &BC) { 243 return buildSectionName(BC.isELF() ? ".local.cold.text." : ".l.c.text.", Name, 244 BC); 245 } 246 247 uint64_t BinaryFunction::Count = 0; 248 249 std::optional<StringRef> 250 BinaryFunction::hasNameRegex(const StringRef Name) const { 251 const std::string RegexName = (Twine("^") + StringRef(Name) + "$").str(); 252 Regex MatchName(RegexName); 253 return forEachName( 254 [&MatchName](StringRef Name) { return MatchName.match(Name); }); 255 } 256 257 std::optional<StringRef> 258 BinaryFunction::hasRestoredNameRegex(const StringRef Name) const { 259 const std::string RegexName = (Twine("^") + StringRef(Name) + "$").str(); 260 Regex MatchName(RegexName); 261 return forEachName([&MatchName](StringRef Name) { 262 return MatchName.match(NameResolver::restore(Name)); 263 }); 264 } 265 266 std::string BinaryFunction::getDemangledName() const { 267 StringRef MangledName = NameResolver::restore(getOneName()); 268 return demangle(MangledName.str()); 269 } 270 271 BinaryBasicBlock * 272 BinaryFunction::getBasicBlockContainingOffset(uint64_t Offset) { 273 if (Offset > Size) 274 return nullptr; 275 276 if (BasicBlockOffsets.empty()) 277 return nullptr; 278 279 /* 280 * This is commented out because it makes BOLT too slow. 281 * assert(std::is_sorted(BasicBlockOffsets.begin(), 282 * BasicBlockOffsets.end(), 283 * CompareBasicBlockOffsets()))); 284 */ 285 auto I = 286 llvm::upper_bound(BasicBlockOffsets, BasicBlockOffset(Offset, nullptr), 287 CompareBasicBlockOffsets()); 288 assert(I != BasicBlockOffsets.begin() && "first basic block not at offset 0"); 289 --I; 290 BinaryBasicBlock *BB = I->second; 291 return (Offset < BB->getOffset() + BB->getOriginalSize()) ? BB : nullptr; 292 } 293 294 void BinaryFunction::markUnreachableBlocks() { 295 std::stack<BinaryBasicBlock *> Stack; 296 297 for (BinaryBasicBlock &BB : blocks()) 298 BB.markValid(false); 299 300 // Add all entries and landing pads as roots. 301 for (BinaryBasicBlock *BB : BasicBlocks) { 302 if (isEntryPoint(*BB) || BB->isLandingPad()) { 303 Stack.push(BB); 304 BB->markValid(true); 305 continue; 306 } 307 // FIXME: 308 // Also mark BBs with indirect jumps as reachable, since we do not 309 // support removing unused jump tables yet (GH-issue20). 310 for (const MCInst &Inst : *BB) { 311 if (BC.MIB->getJumpTable(Inst)) { 312 Stack.push(BB); 313 BB->markValid(true); 314 break; 315 } 316 } 317 } 318 319 // Determine reachable BBs from the entry point 320 while (!Stack.empty()) { 321 BinaryBasicBlock *BB = Stack.top(); 322 Stack.pop(); 323 for (BinaryBasicBlock *Succ : BB->successors()) { 324 if (Succ->isValid()) 325 continue; 326 Succ->markValid(true); 327 Stack.push(Succ); 328 } 329 } 330 } 331 332 // Any unnecessary fallthrough jumps revealed after calling eraseInvalidBBs 333 // will be cleaned up by fixBranches(). 334 std::pair<unsigned, uint64_t> 335 BinaryFunction::eraseInvalidBBs(const MCCodeEmitter *Emitter) { 336 DenseSet<const BinaryBasicBlock *> InvalidBBs; 337 unsigned Count = 0; 338 uint64_t Bytes = 0; 339 for (BinaryBasicBlock *const BB : BasicBlocks) { 340 if (!BB->isValid()) { 341 assert(!isEntryPoint(*BB) && "all entry blocks must be valid"); 342 InvalidBBs.insert(BB); 343 ++Count; 344 Bytes += BC.computeCodeSize(BB->begin(), BB->end(), Emitter); 345 } 346 } 347 348 Layout.eraseBasicBlocks(InvalidBBs); 349 350 BasicBlockListType NewBasicBlocks; 351 for (auto I = BasicBlocks.begin(), E = BasicBlocks.end(); I != E; ++I) { 352 BinaryBasicBlock *BB = *I; 353 if (InvalidBBs.contains(BB)) { 354 // Make sure the block is removed from the list of predecessors. 355 BB->removeAllSuccessors(); 356 DeletedBasicBlocks.push_back(BB); 357 } else { 358 NewBasicBlocks.push_back(BB); 359 } 360 } 361 BasicBlocks = std::move(NewBasicBlocks); 362 363 assert(BasicBlocks.size() == Layout.block_size()); 364 365 // Update CFG state if needed 366 if (Count > 0) 367 recomputeLandingPads(); 368 369 return std::make_pair(Count, Bytes); 370 } 371 372 bool BinaryFunction::isForwardCall(const MCSymbol *CalleeSymbol) const { 373 // This function should work properly before and after function reordering. 374 // In order to accomplish this, we use the function index (if it is valid). 375 // If the function indices are not valid, we fall back to the original 376 // addresses. This should be ok because the functions without valid indices 377 // should have been ordered with a stable sort. 378 const BinaryFunction *CalleeBF = BC.getFunctionForSymbol(CalleeSymbol); 379 if (CalleeBF) { 380 if (CalleeBF->isInjected()) 381 return true; 382 383 if (hasValidIndex() && CalleeBF->hasValidIndex()) { 384 return getIndex() < CalleeBF->getIndex(); 385 } else if (hasValidIndex() && !CalleeBF->hasValidIndex()) { 386 return true; 387 } else if (!hasValidIndex() && CalleeBF->hasValidIndex()) { 388 return false; 389 } else { 390 return getAddress() < CalleeBF->getAddress(); 391 } 392 } else { 393 // Absolute symbol. 394 ErrorOr<uint64_t> CalleeAddressOrError = BC.getSymbolValue(*CalleeSymbol); 395 assert(CalleeAddressOrError && "unregistered symbol found"); 396 return *CalleeAddressOrError > getAddress(); 397 } 398 } 399 400 void BinaryFunction::dump() const { 401 // getDynoStats calls FunctionLayout::updateLayoutIndices and 402 // BasicBlock::analyzeBranch. The former cannot be const, but should be 403 // removed, the latter should be made const, but seems to require refactoring. 404 // Forcing all callers to have a non-const reference to BinaryFunction to call 405 // dump non-const however is not ideal either. Adding this const_cast is right 406 // now the best solution. It is safe, because BinaryFunction itself is not 407 // modified. Only BinaryBasicBlocks are actually modified (if it all) and we 408 // have mutable pointers to those regardless whether this function is 409 // const-qualified or not. 410 const_cast<BinaryFunction &>(*this).print(dbgs(), ""); 411 } 412 413 void BinaryFunction::print(raw_ostream &OS, std::string Annotation) { 414 if (!opts::shouldPrint(*this)) 415 return; 416 417 StringRef SectionName = 418 OriginSection ? OriginSection->getName() : "<no origin section>"; 419 OS << "Binary Function \"" << *this << "\" " << Annotation << " {"; 420 std::vector<StringRef> AllNames = getNames(); 421 if (AllNames.size() > 1) { 422 OS << "\n All names : "; 423 const char *Sep = ""; 424 for (const StringRef &Name : AllNames) { 425 OS << Sep << Name; 426 Sep = "\n "; 427 } 428 } 429 OS << "\n Number : " << FunctionNumber; 430 OS << "\n State : " << CurrentState; 431 OS << "\n Address : 0x" << Twine::utohexstr(Address); 432 OS << "\n Size : 0x" << Twine::utohexstr(Size); 433 OS << "\n MaxSize : 0x" << Twine::utohexstr(MaxSize); 434 OS << "\n Offset : 0x" << Twine::utohexstr(getFileOffset()); 435 OS << "\n Section : " << SectionName; 436 OS << "\n Orc Section : " << getCodeSectionName(); 437 OS << "\n LSDA : 0x" << Twine::utohexstr(getLSDAAddress()); 438 OS << "\n IsSimple : " << IsSimple; 439 OS << "\n IsMultiEntry: " << isMultiEntry(); 440 OS << "\n IsSplit : " << isSplit(); 441 OS << "\n BB Count : " << size(); 442 443 if (HasUnknownControlFlow) 444 OS << "\n Unknown CF : true"; 445 if (getPersonalityFunction()) 446 OS << "\n Personality : " << getPersonalityFunction()->getName(); 447 if (IsFragment) 448 OS << "\n IsFragment : true"; 449 if (isFolded()) 450 OS << "\n FoldedInto : " << *getFoldedIntoFunction(); 451 for (BinaryFunction *ParentFragment : ParentFragments) 452 OS << "\n Parent : " << *ParentFragment; 453 if (!Fragments.empty()) { 454 OS << "\n Fragments : "; 455 ListSeparator LS; 456 for (BinaryFunction *Frag : Fragments) 457 OS << LS << *Frag; 458 } 459 if (hasCFG()) 460 OS << "\n Hash : " << Twine::utohexstr(computeHash()); 461 if (isMultiEntry()) { 462 OS << "\n Secondary Entry Points : "; 463 ListSeparator LS; 464 for (const auto &KV : SecondaryEntryPoints) 465 OS << LS << KV.second->getName(); 466 } 467 if (FrameInstructions.size()) 468 OS << "\n CFI Instrs : " << FrameInstructions.size(); 469 if (!Layout.block_empty()) { 470 OS << "\n BB Layout : "; 471 ListSeparator LS; 472 for (const BinaryBasicBlock *BB : Layout.blocks()) 473 OS << LS << BB->getName(); 474 } 475 if (getImageAddress()) 476 OS << "\n Image : 0x" << Twine::utohexstr(getImageAddress()); 477 if (ExecutionCount != COUNT_NO_PROFILE) { 478 OS << "\n Exec Count : " << ExecutionCount; 479 OS << "\n Branch Count: " << RawBranchCount; 480 OS << "\n Profile Acc : " << format("%.1f%%", ProfileMatchRatio * 100.0f); 481 } 482 483 if (opts::PrintDynoStats && !getLayout().block_empty()) { 484 OS << '\n'; 485 DynoStats dynoStats = getDynoStats(*this); 486 OS << dynoStats; 487 } 488 489 OS << "\n}\n"; 490 491 if (opts::PrintDynoStatsOnly || !BC.InstPrinter) 492 return; 493 494 // Offset of the instruction in function. 495 uint64_t Offset = 0; 496 497 if (BasicBlocks.empty() && !Instructions.empty()) { 498 // Print before CFG was built. 499 for (const std::pair<const uint32_t, MCInst> &II : Instructions) { 500 Offset = II.first; 501 502 // Print label if exists at this offset. 503 auto LI = Labels.find(Offset); 504 if (LI != Labels.end()) { 505 if (const MCSymbol *EntrySymbol = 506 getSecondaryEntryPointSymbol(LI->second)) 507 OS << EntrySymbol->getName() << " (Entry Point):\n"; 508 OS << LI->second->getName() << ":\n"; 509 } 510 511 BC.printInstruction(OS, II.second, Offset, this); 512 } 513 } 514 515 StringRef SplitPointMsg = ""; 516 for (const FunctionFragment &FF : Layout.fragments()) { 517 OS << SplitPointMsg; 518 SplitPointMsg = "------- HOT-COLD SPLIT POINT -------\n\n"; 519 for (const BinaryBasicBlock *BB : FF) { 520 OS << BB->getName() << " (" << BB->size() 521 << " instructions, align : " << BB->getAlignment() << ")\n"; 522 523 if (opts::PrintOutputAddressRange) 524 OS << formatv(" Output Address Range: [{0:x}, {1:x}) ({2} bytes)\n", 525 BB->getOutputAddressRange().first, 526 BB->getOutputAddressRange().second, BB->getOutputSize()); 527 528 if (isEntryPoint(*BB)) { 529 if (MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(*BB)) 530 OS << " Secondary Entry Point: " << EntrySymbol->getName() << '\n'; 531 else 532 OS << " Entry Point\n"; 533 } 534 535 if (BB->isLandingPad()) 536 OS << " Landing Pad\n"; 537 538 uint64_t BBExecCount = BB->getExecutionCount(); 539 if (hasValidProfile()) { 540 OS << " Exec Count : "; 541 if (BB->getExecutionCount() != BinaryBasicBlock::COUNT_NO_PROFILE) 542 OS << BBExecCount << '\n'; 543 else 544 OS << "<unknown>\n"; 545 } 546 if (hasCFI()) 547 OS << " CFI State : " << BB->getCFIState() << '\n'; 548 if (opts::EnableBAT) { 549 OS << " Input offset: 0x" << Twine::utohexstr(BB->getInputOffset()) 550 << "\n"; 551 } 552 if (!BB->pred_empty()) { 553 OS << " Predecessors: "; 554 ListSeparator LS; 555 for (BinaryBasicBlock *Pred : BB->predecessors()) 556 OS << LS << Pred->getName(); 557 OS << '\n'; 558 } 559 if (!BB->throw_empty()) { 560 OS << " Throwers: "; 561 ListSeparator LS; 562 for (BinaryBasicBlock *Throw : BB->throwers()) 563 OS << LS << Throw->getName(); 564 OS << '\n'; 565 } 566 567 Offset = alignTo(Offset, BB->getAlignment()); 568 569 // Note: offsets are imprecise since this is happening prior to 570 // relaxation. 571 Offset = BC.printInstructions(OS, BB->begin(), BB->end(), Offset, this); 572 573 if (!BB->succ_empty()) { 574 OS << " Successors: "; 575 // For more than 2 successors, sort them based on frequency. 576 std::vector<uint64_t> Indices(BB->succ_size()); 577 std::iota(Indices.begin(), Indices.end(), 0); 578 if (BB->succ_size() > 2 && BB->getKnownExecutionCount()) { 579 llvm::stable_sort(Indices, [&](const uint64_t A, const uint64_t B) { 580 return BB->BranchInfo[B] < BB->BranchInfo[A]; 581 }); 582 } 583 ListSeparator LS; 584 for (unsigned I = 0; I < Indices.size(); ++I) { 585 BinaryBasicBlock *Succ = BB->Successors[Indices[I]]; 586 const BinaryBasicBlock::BinaryBranchInfo &BI = 587 BB->BranchInfo[Indices[I]]; 588 OS << LS << Succ->getName(); 589 if (ExecutionCount != COUNT_NO_PROFILE && 590 BI.MispredictedCount != BinaryBasicBlock::COUNT_INFERRED) { 591 OS << " (mispreds: " << BI.MispredictedCount 592 << ", count: " << BI.Count << ")"; 593 } else if (ExecutionCount != COUNT_NO_PROFILE && 594 BI.Count != BinaryBasicBlock::COUNT_NO_PROFILE) { 595 OS << " (inferred count: " << BI.Count << ")"; 596 } 597 } 598 OS << '\n'; 599 } 600 601 if (!BB->lp_empty()) { 602 OS << " Landing Pads: "; 603 ListSeparator LS; 604 for (BinaryBasicBlock *LP : BB->landing_pads()) { 605 OS << LS << LP->getName(); 606 if (ExecutionCount != COUNT_NO_PROFILE) { 607 OS << " (count: " << LP->getExecutionCount() << ")"; 608 } 609 } 610 OS << '\n'; 611 } 612 613 // In CFG_Finalized state we can miscalculate CFI state at exit. 614 if (CurrentState == State::CFG && hasCFI()) { 615 const int32_t CFIStateAtExit = BB->getCFIStateAtExit(); 616 if (CFIStateAtExit >= 0) 617 OS << " CFI State: " << CFIStateAtExit << '\n'; 618 } 619 620 OS << '\n'; 621 } 622 } 623 624 // Dump new exception ranges for the function. 625 if (!CallSites.empty()) { 626 OS << "EH table:\n"; 627 for (const FunctionFragment &FF : getLayout().fragments()) { 628 for (const auto &FCSI : getCallSites(FF.getFragmentNum())) { 629 const CallSite &CSI = FCSI.second; 630 OS << " [" << *CSI.Start << ", " << *CSI.End << ") landing pad : "; 631 if (CSI.LP) 632 OS << *CSI.LP; 633 else 634 OS << "0"; 635 OS << ", action : " << CSI.Action << '\n'; 636 } 637 } 638 OS << '\n'; 639 } 640 641 // Print all jump tables. 642 for (const std::pair<const uint64_t, JumpTable *> &JTI : JumpTables) 643 JTI.second->print(OS); 644 645 OS << "DWARF CFI Instructions:\n"; 646 if (OffsetToCFI.size()) { 647 // Pre-buildCFG information 648 for (const std::pair<const uint32_t, uint32_t> &Elmt : OffsetToCFI) { 649 OS << format(" %08x:\t", Elmt.first); 650 assert(Elmt.second < FrameInstructions.size() && "Incorrect CFI offset"); 651 BinaryContext::printCFI(OS, FrameInstructions[Elmt.second]); 652 OS << "\n"; 653 } 654 } else { 655 // Post-buildCFG information 656 for (uint32_t I = 0, E = FrameInstructions.size(); I != E; ++I) { 657 const MCCFIInstruction &CFI = FrameInstructions[I]; 658 OS << format(" %d:\t", I); 659 BinaryContext::printCFI(OS, CFI); 660 OS << "\n"; 661 } 662 } 663 if (FrameInstructions.empty()) 664 OS << " <empty>\n"; 665 666 OS << "End of Function \"" << *this << "\"\n\n"; 667 } 668 669 void BinaryFunction::printRelocations(raw_ostream &OS, uint64_t Offset, 670 uint64_t Size) const { 671 const char *Sep = " # Relocs: "; 672 673 auto RI = Relocations.lower_bound(Offset); 674 while (RI != Relocations.end() && RI->first < Offset + Size) { 675 OS << Sep << "(R: " << RI->second << ")"; 676 Sep = ", "; 677 ++RI; 678 } 679 } 680 681 static std::string mutateDWARFExpressionTargetReg(const MCCFIInstruction &Instr, 682 MCPhysReg NewReg) { 683 StringRef ExprBytes = Instr.getValues(); 684 assert(ExprBytes.size() > 1 && "DWARF expression CFI is too short"); 685 uint8_t Opcode = ExprBytes[0]; 686 assert((Opcode == dwarf::DW_CFA_expression || 687 Opcode == dwarf::DW_CFA_val_expression) && 688 "invalid DWARF expression CFI"); 689 (void)Opcode; 690 const uint8_t *const Start = 691 reinterpret_cast<const uint8_t *>(ExprBytes.drop_front(1).data()); 692 const uint8_t *const End = 693 reinterpret_cast<const uint8_t *>(Start + ExprBytes.size() - 1); 694 unsigned Size = 0; 695 decodeULEB128(Start, &Size, End); 696 assert(Size > 0 && "Invalid reg encoding for DWARF expression CFI"); 697 SmallString<8> Tmp; 698 raw_svector_ostream OSE(Tmp); 699 encodeULEB128(NewReg, OSE); 700 return Twine(ExprBytes.slice(0, 1)) 701 .concat(OSE.str()) 702 .concat(ExprBytes.drop_front(1 + Size)) 703 .str(); 704 } 705 706 void BinaryFunction::mutateCFIRegisterFor(const MCInst &Instr, 707 MCPhysReg NewReg) { 708 const MCCFIInstruction *OldCFI = getCFIFor(Instr); 709 assert(OldCFI && "invalid CFI instr"); 710 switch (OldCFI->getOperation()) { 711 default: 712 llvm_unreachable("Unexpected instruction"); 713 case MCCFIInstruction::OpDefCfa: 714 setCFIFor(Instr, MCCFIInstruction::cfiDefCfa(nullptr, NewReg, 715 OldCFI->getOffset())); 716 break; 717 case MCCFIInstruction::OpDefCfaRegister: 718 setCFIFor(Instr, MCCFIInstruction::createDefCfaRegister(nullptr, NewReg)); 719 break; 720 case MCCFIInstruction::OpOffset: 721 setCFIFor(Instr, MCCFIInstruction::createOffset(nullptr, NewReg, 722 OldCFI->getOffset())); 723 break; 724 case MCCFIInstruction::OpRegister: 725 setCFIFor(Instr, MCCFIInstruction::createRegister(nullptr, NewReg, 726 OldCFI->getRegister2())); 727 break; 728 case MCCFIInstruction::OpSameValue: 729 setCFIFor(Instr, MCCFIInstruction::createSameValue(nullptr, NewReg)); 730 break; 731 case MCCFIInstruction::OpEscape: 732 setCFIFor(Instr, 733 MCCFIInstruction::createEscape( 734 nullptr, 735 StringRef(mutateDWARFExpressionTargetReg(*OldCFI, NewReg)))); 736 break; 737 case MCCFIInstruction::OpRestore: 738 setCFIFor(Instr, MCCFIInstruction::createRestore(nullptr, NewReg)); 739 break; 740 case MCCFIInstruction::OpUndefined: 741 setCFIFor(Instr, MCCFIInstruction::createUndefined(nullptr, NewReg)); 742 break; 743 } 744 } 745 746 const MCCFIInstruction *BinaryFunction::mutateCFIOffsetFor(const MCInst &Instr, 747 int64_t NewOffset) { 748 const MCCFIInstruction *OldCFI = getCFIFor(Instr); 749 assert(OldCFI && "invalid CFI instr"); 750 switch (OldCFI->getOperation()) { 751 default: 752 llvm_unreachable("Unexpected instruction"); 753 case MCCFIInstruction::OpDefCfaOffset: 754 setCFIFor(Instr, MCCFIInstruction::cfiDefCfaOffset(nullptr, NewOffset)); 755 break; 756 case MCCFIInstruction::OpAdjustCfaOffset: 757 setCFIFor(Instr, 758 MCCFIInstruction::createAdjustCfaOffset(nullptr, NewOffset)); 759 break; 760 case MCCFIInstruction::OpDefCfa: 761 setCFIFor(Instr, MCCFIInstruction::cfiDefCfa(nullptr, OldCFI->getRegister(), 762 NewOffset)); 763 break; 764 case MCCFIInstruction::OpOffset: 765 setCFIFor(Instr, MCCFIInstruction::createOffset( 766 nullptr, OldCFI->getRegister(), NewOffset)); 767 break; 768 } 769 return getCFIFor(Instr); 770 } 771 772 IndirectBranchType 773 BinaryFunction::processIndirectBranch(MCInst &Instruction, unsigned Size, 774 uint64_t Offset, 775 uint64_t &TargetAddress) { 776 const unsigned PtrSize = BC.AsmInfo->getCodePointerSize(); 777 778 // The instruction referencing memory used by the branch instruction. 779 // It could be the branch instruction itself or one of the instructions 780 // setting the value of the register used by the branch. 781 MCInst *MemLocInstr; 782 783 // The instruction loading the fixed PIC jump table entry value. 784 MCInst *FixedEntryLoadInstr; 785 786 // Address of the table referenced by MemLocInstr. Could be either an 787 // array of function pointers, or a jump table. 788 uint64_t ArrayStart = 0; 789 790 unsigned BaseRegNum, IndexRegNum; 791 int64_t DispValue; 792 const MCExpr *DispExpr; 793 794 // In AArch, identify the instruction adding the PC-relative offset to 795 // jump table entries to correctly decode it. 796 MCInst *PCRelBaseInstr; 797 uint64_t PCRelAddr = 0; 798 799 auto Begin = Instructions.begin(); 800 if (BC.isAArch64()) { 801 PreserveNops = BC.HasRelocations; 802 // Start at the last label as an approximation of the current basic block. 803 // This is a heuristic, since the full set of labels have yet to be 804 // determined 805 for (const uint32_t Offset : 806 llvm::make_first_range(llvm::reverse(Labels))) { 807 auto II = Instructions.find(Offset); 808 if (II != Instructions.end()) { 809 Begin = II; 810 break; 811 } 812 } 813 } 814 815 IndirectBranchType BranchType = BC.MIB->analyzeIndirectBranch( 816 Instruction, Begin, Instructions.end(), PtrSize, MemLocInstr, BaseRegNum, 817 IndexRegNum, DispValue, DispExpr, PCRelBaseInstr, FixedEntryLoadInstr); 818 819 if (BranchType == IndirectBranchType::UNKNOWN && !MemLocInstr) 820 return BranchType; 821 822 if (MemLocInstr != &Instruction) 823 IndexRegNum = BC.MIB->getNoRegister(); 824 825 if (BC.isAArch64()) { 826 const MCSymbol *Sym = BC.MIB->getTargetSymbol(*PCRelBaseInstr, 1); 827 assert(Sym && "Symbol extraction failed"); 828 ErrorOr<uint64_t> SymValueOrError = BC.getSymbolValue(*Sym); 829 if (SymValueOrError) { 830 PCRelAddr = *SymValueOrError; 831 } else { 832 for (std::pair<const uint32_t, MCSymbol *> &Elmt : Labels) { 833 if (Elmt.second == Sym) { 834 PCRelAddr = Elmt.first + getAddress(); 835 break; 836 } 837 } 838 } 839 uint64_t InstrAddr = 0; 840 for (auto II = Instructions.rbegin(); II != Instructions.rend(); ++II) { 841 if (&II->second == PCRelBaseInstr) { 842 InstrAddr = II->first + getAddress(); 843 break; 844 } 845 } 846 assert(InstrAddr != 0 && "instruction not found"); 847 // We do this to avoid spurious references to code locations outside this 848 // function (for example, if the indirect jump lives in the last basic 849 // block of the function, it will create a reference to the next function). 850 // This replaces a symbol reference with an immediate. 851 BC.MIB->replaceMemOperandDisp(*PCRelBaseInstr, 852 MCOperand::createImm(PCRelAddr - InstrAddr)); 853 // FIXME: Disable full jump table processing for AArch64 until we have a 854 // proper way of determining the jump table limits. 855 return IndirectBranchType::UNKNOWN; 856 } 857 858 auto getExprValue = [&](const MCExpr *Expr) { 859 const MCSymbol *TargetSym; 860 uint64_t TargetOffset; 861 std::tie(TargetSym, TargetOffset) = BC.MIB->getTargetSymbolInfo(Expr); 862 ErrorOr<uint64_t> SymValueOrError = BC.getSymbolValue(*TargetSym); 863 assert(SymValueOrError && "Global symbol needs a value"); 864 return *SymValueOrError + TargetOffset; 865 }; 866 867 // RIP-relative addressing should be converted to symbol form by now 868 // in processed instructions (but not in jump). 869 if (DispExpr) { 870 ArrayStart = getExprValue(DispExpr); 871 BaseRegNum = BC.MIB->getNoRegister(); 872 if (BC.isAArch64()) { 873 ArrayStart &= ~0xFFFULL; 874 ArrayStart += DispValue & 0xFFFULL; 875 } 876 } else { 877 ArrayStart = static_cast<uint64_t>(DispValue); 878 } 879 880 if (BaseRegNum == BC.MRI->getProgramCounter()) 881 ArrayStart += getAddress() + Offset + Size; 882 883 if (FixedEntryLoadInstr) { 884 assert(BranchType == IndirectBranchType::POSSIBLE_PIC_FIXED_BRANCH && 885 "Invalid IndirectBranch type"); 886 MCInst::iterator FixedEntryDispOperand = 887 BC.MIB->getMemOperandDisp(*FixedEntryLoadInstr); 888 assert(FixedEntryDispOperand != FixedEntryLoadInstr->end() && 889 "Invalid memory instruction"); 890 const MCExpr *FixedEntryDispExpr = FixedEntryDispOperand->getExpr(); 891 const uint64_t EntryAddress = getExprValue(FixedEntryDispExpr); 892 uint64_t EntrySize = BC.getJumpTableEntrySize(JumpTable::JTT_PIC); 893 ErrorOr<int64_t> Value = 894 BC.getSignedValueAtAddress(EntryAddress, EntrySize); 895 if (!Value) 896 return IndirectBranchType::UNKNOWN; 897 898 BC.outs() << "BOLT-INFO: fixed PIC indirect branch detected in " << *this 899 << " at 0x" << Twine::utohexstr(getAddress() + Offset) 900 << " referencing data at 0x" << Twine::utohexstr(EntryAddress) 901 << " the destination value is 0x" 902 << Twine::utohexstr(ArrayStart + *Value) << '\n'; 903 904 TargetAddress = ArrayStart + *Value; 905 906 // Remove spurious JumpTable at EntryAddress caused by PIC reference from 907 // the load instruction. 908 BC.deleteJumpTable(EntryAddress); 909 910 // Replace FixedEntryDispExpr used in target address calculation with outer 911 // jump table reference. 912 JumpTable *JT = BC.getJumpTableContainingAddress(ArrayStart); 913 assert(JT && "Must have a containing jump table for PIC fixed branch"); 914 BC.MIB->replaceMemOperandDisp(*FixedEntryLoadInstr, JT->getFirstLabel(), 915 EntryAddress - ArrayStart, &*BC.Ctx); 916 917 return BranchType; 918 } 919 920 LLVM_DEBUG(dbgs() << "BOLT-DEBUG: addressed memory is 0x" 921 << Twine::utohexstr(ArrayStart) << '\n'); 922 923 ErrorOr<BinarySection &> Section = BC.getSectionForAddress(ArrayStart); 924 if (!Section) { 925 // No section - possibly an absolute address. Since we don't allow 926 // internal function addresses to escape the function scope - we 927 // consider it a tail call. 928 if (opts::Verbosity >= 1) { 929 BC.errs() << "BOLT-WARNING: no section for address 0x" 930 << Twine::utohexstr(ArrayStart) << " referenced from function " 931 << *this << '\n'; 932 } 933 return IndirectBranchType::POSSIBLE_TAIL_CALL; 934 } 935 if (Section->isVirtual()) { 936 // The contents are filled at runtime. 937 return IndirectBranchType::POSSIBLE_TAIL_CALL; 938 } 939 940 if (BranchType == IndirectBranchType::POSSIBLE_FIXED_BRANCH) { 941 ErrorOr<uint64_t> Value = BC.getPointerAtAddress(ArrayStart); 942 if (!Value) 943 return IndirectBranchType::UNKNOWN; 944 945 if (BC.getSectionForAddress(ArrayStart)->isWritable()) 946 return IndirectBranchType::UNKNOWN; 947 948 BC.outs() << "BOLT-INFO: fixed indirect branch detected in " << *this 949 << " at 0x" << Twine::utohexstr(getAddress() + Offset) 950 << " referencing data at 0x" << Twine::utohexstr(ArrayStart) 951 << " the destination value is 0x" << Twine::utohexstr(*Value) 952 << '\n'; 953 954 TargetAddress = *Value; 955 return BranchType; 956 } 957 958 // Check if there's already a jump table registered at this address. 959 MemoryContentsType MemType; 960 if (JumpTable *JT = BC.getJumpTableContainingAddress(ArrayStart)) { 961 switch (JT->Type) { 962 case JumpTable::JTT_NORMAL: 963 MemType = MemoryContentsType::POSSIBLE_JUMP_TABLE; 964 break; 965 case JumpTable::JTT_PIC: 966 MemType = MemoryContentsType::POSSIBLE_PIC_JUMP_TABLE; 967 break; 968 } 969 } else { 970 MemType = BC.analyzeMemoryAt(ArrayStart, *this); 971 } 972 973 // Check that jump table type in instruction pattern matches memory contents. 974 JumpTable::JumpTableType JTType; 975 if (BranchType == IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE) { 976 if (MemType != MemoryContentsType::POSSIBLE_PIC_JUMP_TABLE) 977 return IndirectBranchType::UNKNOWN; 978 JTType = JumpTable::JTT_PIC; 979 } else { 980 if (MemType == MemoryContentsType::POSSIBLE_PIC_JUMP_TABLE) 981 return IndirectBranchType::UNKNOWN; 982 983 if (MemType == MemoryContentsType::UNKNOWN) 984 return IndirectBranchType::POSSIBLE_TAIL_CALL; 985 986 BranchType = IndirectBranchType::POSSIBLE_JUMP_TABLE; 987 JTType = JumpTable::JTT_NORMAL; 988 } 989 990 // Convert the instruction into jump table branch. 991 const MCSymbol *JTLabel = BC.getOrCreateJumpTable(*this, ArrayStart, JTType); 992 BC.MIB->replaceMemOperandDisp(*MemLocInstr, JTLabel, BC.Ctx.get()); 993 BC.MIB->setJumpTable(Instruction, ArrayStart, IndexRegNum); 994 995 JTSites.emplace_back(Offset, ArrayStart); 996 997 return BranchType; 998 } 999 1000 MCSymbol *BinaryFunction::getOrCreateLocalLabel(uint64_t Address, 1001 bool CreatePastEnd) { 1002 const uint64_t Offset = Address - getAddress(); 1003 1004 if ((Offset == getSize()) && CreatePastEnd) 1005 return getFunctionEndLabel(); 1006 1007 auto LI = Labels.find(Offset); 1008 if (LI != Labels.end()) 1009 return LI->second; 1010 1011 // For AArch64, check if this address is part of a constant island. 1012 if (BC.isAArch64()) { 1013 if (MCSymbol *IslandSym = getOrCreateIslandAccess(Address)) 1014 return IslandSym; 1015 } 1016 1017 MCSymbol *Label = BC.Ctx->createNamedTempSymbol(); 1018 Labels[Offset] = Label; 1019 1020 return Label; 1021 } 1022 1023 ErrorOr<ArrayRef<uint8_t>> BinaryFunction::getData() const { 1024 BinarySection &Section = *getOriginSection(); 1025 assert(Section.containsRange(getAddress(), getMaxSize()) && 1026 "wrong section for function"); 1027 1028 if (!Section.isText() || Section.isVirtual() || !Section.getSize()) 1029 return std::make_error_code(std::errc::bad_address); 1030 1031 StringRef SectionContents = Section.getContents(); 1032 1033 assert(SectionContents.size() == Section.getSize() && 1034 "section size mismatch"); 1035 1036 // Function offset from the section start. 1037 uint64_t Offset = getAddress() - Section.getAddress(); 1038 auto *Bytes = reinterpret_cast<const uint8_t *>(SectionContents.data()); 1039 return ArrayRef<uint8_t>(Bytes + Offset, getMaxSize()); 1040 } 1041 1042 size_t BinaryFunction::getSizeOfDataInCodeAt(uint64_t Offset) const { 1043 if (!Islands) 1044 return 0; 1045 1046 if (!llvm::is_contained(Islands->DataOffsets, Offset)) 1047 return 0; 1048 1049 auto Iter = Islands->CodeOffsets.upper_bound(Offset); 1050 if (Iter != Islands->CodeOffsets.end()) 1051 return *Iter - Offset; 1052 return getSize() - Offset; 1053 } 1054 1055 bool BinaryFunction::isZeroPaddingAt(uint64_t Offset) const { 1056 ArrayRef<uint8_t> FunctionData = *getData(); 1057 uint64_t EndOfCode = getSize(); 1058 if (Islands) { 1059 auto Iter = Islands->DataOffsets.upper_bound(Offset); 1060 if (Iter != Islands->DataOffsets.end()) 1061 EndOfCode = *Iter; 1062 } 1063 for (uint64_t I = Offset; I < EndOfCode; ++I) 1064 if (FunctionData[I] != 0) 1065 return false; 1066 1067 return true; 1068 } 1069 1070 Error BinaryFunction::handlePCRelOperand(MCInst &Instruction, uint64_t Address, 1071 uint64_t Size) { 1072 auto &MIB = BC.MIB; 1073 uint64_t TargetAddress = 0; 1074 if (!MIB->evaluateMemOperandTarget(Instruction, TargetAddress, Address, 1075 Size)) { 1076 std::string Msg; 1077 raw_string_ostream SS(Msg); 1078 SS << "BOLT-ERROR: PC-relative operand can't be evaluated:\n"; 1079 BC.InstPrinter->printInst(&Instruction, 0, "", *BC.STI, SS); 1080 SS << '\n'; 1081 Instruction.dump_pretty(SS, BC.InstPrinter.get()); 1082 SS << '\n'; 1083 SS << "BOLT-ERROR: cannot handle PC-relative operand at 0x" 1084 << Twine::utohexstr(Address) << ". Skipping function " << *this << ".\n"; 1085 if (BC.HasRelocations) 1086 return createFatalBOLTError(Msg); 1087 IsSimple = false; 1088 return createNonFatalBOLTError(Msg); 1089 } 1090 if (TargetAddress == 0 && opts::Verbosity >= 1) { 1091 BC.outs() << "BOLT-INFO: PC-relative operand is zero in function " << *this 1092 << '\n'; 1093 } 1094 1095 const MCSymbol *TargetSymbol; 1096 uint64_t TargetOffset; 1097 std::tie(TargetSymbol, TargetOffset) = 1098 BC.handleAddressRef(TargetAddress, *this, /*IsPCRel*/ true); 1099 1100 bool ReplaceSuccess = MIB->replaceMemOperandDisp( 1101 Instruction, TargetSymbol, static_cast<int64_t>(TargetOffset), &*BC.Ctx); 1102 (void)ReplaceSuccess; 1103 assert(ReplaceSuccess && "Failed to replace mem operand with symbol+off."); 1104 return Error::success(); 1105 } 1106 1107 MCSymbol *BinaryFunction::handleExternalReference(MCInst &Instruction, 1108 uint64_t Size, 1109 uint64_t Offset, 1110 uint64_t TargetAddress, 1111 bool &IsCall) { 1112 auto &MIB = BC.MIB; 1113 1114 const uint64_t AbsoluteInstrAddr = getAddress() + Offset; 1115 BC.addInterproceduralReference(this, TargetAddress); 1116 if (opts::Verbosity >= 2 && !IsCall && Size == 2 && !BC.HasRelocations) { 1117 BC.errs() << "BOLT-WARNING: relaxed tail call detected at 0x" 1118 << Twine::utohexstr(AbsoluteInstrAddr) << " in function " << *this 1119 << ". Code size will be increased.\n"; 1120 } 1121 1122 assert(!MIB->isTailCall(Instruction) && 1123 "synthetic tail call instruction found"); 1124 1125 // This is a call regardless of the opcode. 1126 // Assign proper opcode for tail calls, so that they could be 1127 // treated as calls. 1128 if (!IsCall) { 1129 if (!MIB->convertJmpToTailCall(Instruction)) { 1130 assert(MIB->isConditionalBranch(Instruction) && 1131 "unknown tail call instruction"); 1132 if (opts::Verbosity >= 2) { 1133 BC.errs() << "BOLT-WARNING: conditional tail call detected in " 1134 << "function " << *this << " at 0x" 1135 << Twine::utohexstr(AbsoluteInstrAddr) << ".\n"; 1136 } 1137 } 1138 IsCall = true; 1139 } 1140 1141 if (opts::Verbosity >= 2 && TargetAddress == 0) { 1142 // We actually see calls to address 0 in presence of weak 1143 // symbols originating from libraries. This code is never meant 1144 // to be executed. 1145 BC.outs() << "BOLT-INFO: Function " << *this 1146 << " has a call to address zero.\n"; 1147 } 1148 1149 return BC.getOrCreateGlobalSymbol(TargetAddress, "FUNCat"); 1150 } 1151 1152 void BinaryFunction::handleIndirectBranch(MCInst &Instruction, uint64_t Size, 1153 uint64_t Offset) { 1154 auto &MIB = BC.MIB; 1155 uint64_t IndirectTarget = 0; 1156 IndirectBranchType Result = 1157 processIndirectBranch(Instruction, Size, Offset, IndirectTarget); 1158 switch (Result) { 1159 default: 1160 llvm_unreachable("unexpected result"); 1161 case IndirectBranchType::POSSIBLE_TAIL_CALL: { 1162 bool Result = MIB->convertJmpToTailCall(Instruction); 1163 (void)Result; 1164 assert(Result); 1165 break; 1166 } 1167 case IndirectBranchType::POSSIBLE_JUMP_TABLE: 1168 case IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE: 1169 case IndirectBranchType::POSSIBLE_PIC_FIXED_BRANCH: 1170 if (opts::JumpTables == JTS_NONE) 1171 IsSimple = false; 1172 break; 1173 case IndirectBranchType::POSSIBLE_FIXED_BRANCH: { 1174 if (containsAddress(IndirectTarget)) { 1175 const MCSymbol *TargetSymbol = getOrCreateLocalLabel(IndirectTarget); 1176 Instruction.clear(); 1177 MIB->createUncondBranch(Instruction, TargetSymbol, BC.Ctx.get()); 1178 TakenBranches.emplace_back(Offset, IndirectTarget - getAddress()); 1179 addEntryPointAtOffset(IndirectTarget - getAddress()); 1180 } else { 1181 MIB->convertJmpToTailCall(Instruction); 1182 BC.addInterproceduralReference(this, IndirectTarget); 1183 } 1184 break; 1185 } 1186 case IndirectBranchType::UNKNOWN: 1187 // Keep processing. We'll do more checks and fixes in 1188 // postProcessIndirectBranches(). 1189 UnknownIndirectBranchOffsets.emplace(Offset); 1190 break; 1191 } 1192 } 1193 1194 void BinaryFunction::handleAArch64IndirectCall(MCInst &Instruction, 1195 const uint64_t Offset) { 1196 auto &MIB = BC.MIB; 1197 const uint64_t AbsoluteInstrAddr = getAddress() + Offset; 1198 MCInst *TargetHiBits, *TargetLowBits; 1199 uint64_t TargetAddress, Count; 1200 Count = MIB->matchLinkerVeneer(Instructions.begin(), Instructions.end(), 1201 AbsoluteInstrAddr, Instruction, TargetHiBits, 1202 TargetLowBits, TargetAddress); 1203 if (Count) { 1204 MIB->addAnnotation(Instruction, "AArch64Veneer", true); 1205 --Count; 1206 for (auto It = std::prev(Instructions.end()); Count != 0; 1207 It = std::prev(It), --Count) { 1208 MIB->addAnnotation(It->second, "AArch64Veneer", true); 1209 } 1210 1211 BC.addAdrpAddRelocAArch64(*this, *TargetLowBits, *TargetHiBits, 1212 TargetAddress); 1213 } 1214 } 1215 1216 std::optional<MCInst> 1217 BinaryFunction::disassembleInstructionAtOffset(uint64_t Offset) const { 1218 assert(CurrentState == State::Empty && "Function should not be disassembled"); 1219 assert(Offset < MaxSize && "Invalid offset"); 1220 ErrorOr<ArrayRef<unsigned char>> FunctionData = getData(); 1221 assert(FunctionData && "Cannot get function as data"); 1222 MCInst Instr; 1223 uint64_t InstrSize = 0; 1224 const uint64_t InstrAddress = getAddress() + Offset; 1225 if (BC.DisAsm->getInstruction(Instr, InstrSize, FunctionData->slice(Offset), 1226 InstrAddress, nulls())) 1227 return Instr; 1228 return std::nullopt; 1229 } 1230 1231 Error BinaryFunction::disassemble() { 1232 NamedRegionTimer T("disassemble", "Disassemble function", "buildfuncs", 1233 "Build Binary Functions", opts::TimeBuild); 1234 ErrorOr<ArrayRef<uint8_t>> ErrorOrFunctionData = getData(); 1235 assert(ErrorOrFunctionData && "function data is not available"); 1236 ArrayRef<uint8_t> FunctionData = *ErrorOrFunctionData; 1237 assert(FunctionData.size() == getMaxSize() && 1238 "function size does not match raw data size"); 1239 1240 auto &Ctx = BC.Ctx; 1241 auto &MIB = BC.MIB; 1242 1243 BC.SymbolicDisAsm->setSymbolizer(MIB->createTargetSymbolizer(*this)); 1244 1245 // Insert a label at the beginning of the function. This will be our first 1246 // basic block. 1247 Labels[0] = Ctx->createNamedTempSymbol("BB0"); 1248 1249 // Map offsets in the function to a label that should always point to the 1250 // corresponding instruction. This is used for labels that shouldn't point to 1251 // the start of a basic block but always to a specific instruction. This is 1252 // used, for example, on RISC-V where %pcrel_lo relocations point to the 1253 // corresponding %pcrel_hi. 1254 LabelsMapType InstructionLabels; 1255 1256 uint64_t Size = 0; // instruction size 1257 for (uint64_t Offset = 0; Offset < getSize(); Offset += Size) { 1258 MCInst Instruction; 1259 const uint64_t AbsoluteInstrAddr = getAddress() + Offset; 1260 1261 // Check for data inside code and ignore it 1262 if (const size_t DataInCodeSize = getSizeOfDataInCodeAt(Offset)) { 1263 Size = DataInCodeSize; 1264 continue; 1265 } 1266 1267 if (!BC.SymbolicDisAsm->getInstruction(Instruction, Size, 1268 FunctionData.slice(Offset), 1269 AbsoluteInstrAddr, nulls())) { 1270 // Functions with "soft" boundaries, e.g. coming from assembly source, 1271 // can have 0-byte padding at the end. 1272 if (isZeroPaddingAt(Offset)) 1273 break; 1274 1275 BC.errs() 1276 << "BOLT-WARNING: unable to disassemble instruction at offset 0x" 1277 << Twine::utohexstr(Offset) << " (address 0x" 1278 << Twine::utohexstr(AbsoluteInstrAddr) << ") in function " << *this 1279 << '\n'; 1280 // Some AVX-512 instructions could not be disassembled at all. 1281 if (BC.HasRelocations && opts::TrapOnAVX512 && BC.isX86()) { 1282 setTrapOnEntry(); 1283 BC.TrappedFunctions.push_back(this); 1284 } else { 1285 setIgnored(); 1286 } 1287 1288 break; 1289 } 1290 1291 // Check integrity of LLVM assembler/disassembler. 1292 if (opts::CheckEncoding && !BC.MIB->isBranch(Instruction) && 1293 !BC.MIB->isCall(Instruction) && !BC.MIB->isNoop(Instruction)) { 1294 if (!BC.validateInstructionEncoding(FunctionData.slice(Offset, Size))) { 1295 BC.errs() << "BOLT-WARNING: mismatching LLVM encoding detected in " 1296 << "function " << *this << " for instruction :\n"; 1297 BC.printInstruction(BC.errs(), Instruction, AbsoluteInstrAddr); 1298 BC.errs() << '\n'; 1299 } 1300 } 1301 1302 // Special handling for AVX-512 instructions. 1303 if (MIB->hasEVEXEncoding(Instruction)) { 1304 if (BC.HasRelocations && opts::TrapOnAVX512) { 1305 setTrapOnEntry(); 1306 BC.TrappedFunctions.push_back(this); 1307 break; 1308 } 1309 1310 if (!BC.validateInstructionEncoding(FunctionData.slice(Offset, Size))) { 1311 BC.errs() << "BOLT-WARNING: internal assembler/disassembler error " 1312 "detected for AVX512 instruction:\n"; 1313 BC.printInstruction(BC.errs(), Instruction, AbsoluteInstrAddr); 1314 BC.errs() << " in function " << *this << '\n'; 1315 setIgnored(); 1316 break; 1317 } 1318 } 1319 1320 bool IsUnsupported = BC.MIB->isUnsupportedInstruction(Instruction); 1321 if (IsUnsupported) 1322 setIgnored(); 1323 1324 if (MIB->isBranch(Instruction) || MIB->isCall(Instruction)) { 1325 uint64_t TargetAddress = 0; 1326 if (MIB->evaluateBranch(Instruction, AbsoluteInstrAddr, Size, 1327 TargetAddress)) { 1328 // Check if the target is within the same function. Otherwise it's 1329 // a call, possibly a tail call. 1330 // 1331 // If the target *is* the function address it could be either a branch 1332 // or a recursive call. 1333 bool IsCall = MIB->isCall(Instruction); 1334 const bool IsCondBranch = MIB->isConditionalBranch(Instruction); 1335 MCSymbol *TargetSymbol = nullptr; 1336 1337 if (IsUnsupported) 1338 if (auto *TargetFunc = 1339 BC.getBinaryFunctionContainingAddress(TargetAddress)) 1340 TargetFunc->setIgnored(); 1341 1342 if (IsCall && containsAddress(TargetAddress)) { 1343 if (TargetAddress == getAddress()) { 1344 // Recursive call. 1345 TargetSymbol = getSymbol(); 1346 } else { 1347 if (BC.isX86()) { 1348 // Dangerous old-style x86 PIC code. We may need to freeze this 1349 // function, so preserve the function as is for now. 1350 PreserveNops = true; 1351 } else { 1352 BC.errs() << "BOLT-WARNING: internal call detected at 0x" 1353 << Twine::utohexstr(AbsoluteInstrAddr) 1354 << " in function " << *this << ". Skipping.\n"; 1355 IsSimple = false; 1356 } 1357 } 1358 } 1359 1360 if (!TargetSymbol) { 1361 // Create either local label or external symbol. 1362 if (containsAddress(TargetAddress)) { 1363 TargetSymbol = getOrCreateLocalLabel(TargetAddress); 1364 } else { 1365 if (TargetAddress == getAddress() + getSize() && 1366 TargetAddress < getAddress() + getMaxSize() && 1367 !(BC.isAArch64() && 1368 BC.handleAArch64Veneer(TargetAddress, /*MatchOnly*/ true))) { 1369 // Result of __builtin_unreachable(). 1370 LLVM_DEBUG(dbgs() << "BOLT-DEBUG: jump past end detected at 0x" 1371 << Twine::utohexstr(AbsoluteInstrAddr) 1372 << " in function " << *this 1373 << " : replacing with nop.\n"); 1374 BC.MIB->createNoop(Instruction); 1375 if (IsCondBranch) { 1376 // Register branch offset for profile validation. 1377 IgnoredBranches.emplace_back(Offset, Offset + Size); 1378 } 1379 goto add_instruction; 1380 } 1381 // May update Instruction and IsCall 1382 TargetSymbol = handleExternalReference(Instruction, Size, Offset, 1383 TargetAddress, IsCall); 1384 } 1385 } 1386 1387 if (!IsCall) { 1388 // Add taken branch info. 1389 TakenBranches.emplace_back(Offset, TargetAddress - getAddress()); 1390 } 1391 BC.MIB->replaceBranchTarget(Instruction, TargetSymbol, &*Ctx); 1392 1393 // Mark CTC. 1394 if (IsCondBranch && IsCall) 1395 MIB->setConditionalTailCall(Instruction, TargetAddress); 1396 } else { 1397 // Could not evaluate branch. Should be an indirect call or an 1398 // indirect branch. Bail out on the latter case. 1399 if (MIB->isIndirectBranch(Instruction)) 1400 handleIndirectBranch(Instruction, Size, Offset); 1401 // Indirect call. We only need to fix it if the operand is RIP-relative. 1402 if (IsSimple && MIB->hasPCRelOperand(Instruction)) { 1403 if (auto NewE = handleErrors( 1404 handlePCRelOperand(Instruction, AbsoluteInstrAddr, Size), 1405 [&](const BOLTError &E) -> Error { 1406 if (E.isFatal()) 1407 return Error(std::make_unique<BOLTError>(std::move(E))); 1408 if (!E.getMessage().empty()) 1409 E.log(BC.errs()); 1410 return Error::success(); 1411 })) { 1412 return Error(std::move(NewE)); 1413 } 1414 } 1415 1416 if (BC.isAArch64()) 1417 handleAArch64IndirectCall(Instruction, Offset); 1418 } 1419 } else if (BC.isAArch64() || BC.isRISCV()) { 1420 // Check if there's a relocation associated with this instruction. 1421 bool UsedReloc = false; 1422 for (auto Itr = Relocations.lower_bound(Offset), 1423 ItrE = Relocations.lower_bound(Offset + Size); 1424 Itr != ItrE; ++Itr) { 1425 const Relocation &Relocation = Itr->second; 1426 MCSymbol *Symbol = Relocation.Symbol; 1427 1428 if (Relocation::isInstructionReference(Relocation.Type)) { 1429 uint64_t RefOffset = Relocation.Value - getAddress(); 1430 LabelsMapType::iterator LI = InstructionLabels.find(RefOffset); 1431 1432 if (LI == InstructionLabels.end()) { 1433 Symbol = BC.Ctx->createNamedTempSymbol(); 1434 InstructionLabels.emplace(RefOffset, Symbol); 1435 } else { 1436 Symbol = LI->second; 1437 } 1438 } 1439 1440 int64_t Value = Relocation.Value; 1441 const bool Result = BC.MIB->replaceImmWithSymbolRef( 1442 Instruction, Symbol, Relocation.Addend, Ctx.get(), Value, 1443 Relocation.Type); 1444 (void)Result; 1445 assert(Result && "cannot replace immediate with relocation"); 1446 1447 // For aarch64, if we replaced an immediate with a symbol from a 1448 // relocation, we mark it so we do not try to further process a 1449 // pc-relative operand. All we need is the symbol. 1450 UsedReloc = true; 1451 } 1452 1453 if (!BC.isRISCV() && MIB->hasPCRelOperand(Instruction) && !UsedReloc) { 1454 if (auto NewE = handleErrors( 1455 handlePCRelOperand(Instruction, AbsoluteInstrAddr, Size), 1456 [&](const BOLTError &E) -> Error { 1457 if (E.isFatal()) 1458 return Error(std::make_unique<BOLTError>(std::move(E))); 1459 if (!E.getMessage().empty()) 1460 E.log(BC.errs()); 1461 return Error::success(); 1462 })) 1463 return Error(std::move(NewE)); 1464 } 1465 } 1466 1467 add_instruction: 1468 if (getDWARFLineTable()) { 1469 Instruction.setLoc(findDebugLineInformationForInstructionAt( 1470 AbsoluteInstrAddr, getDWARFUnit(), getDWARFLineTable())); 1471 } 1472 1473 // Record offset of the instruction for profile matching. 1474 if (BC.keepOffsetForInstruction(Instruction)) 1475 MIB->setOffset(Instruction, static_cast<uint32_t>(Offset)); 1476 1477 if (BC.isX86() && BC.MIB->isNoop(Instruction)) { 1478 // NOTE: disassembly loses the correct size information for noops on x86. 1479 // E.g. nopw 0x0(%rax,%rax,1) is 9 bytes, but re-encoded it's only 1480 // 5 bytes. Preserve the size info using annotations. 1481 MIB->setSize(Instruction, Size); 1482 } 1483 1484 addInstruction(Offset, std::move(Instruction)); 1485 } 1486 1487 for (auto [Offset, Label] : InstructionLabels) { 1488 InstrMapType::iterator II = Instructions.find(Offset); 1489 assert(II != Instructions.end() && "reference to non-existing instruction"); 1490 1491 BC.MIB->setInstLabel(II->second, Label); 1492 } 1493 1494 // Reset symbolizer for the disassembler. 1495 BC.SymbolicDisAsm->setSymbolizer(nullptr); 1496 1497 if (uint64_t Offset = getFirstInstructionOffset()) 1498 Labels[Offset] = BC.Ctx->createNamedTempSymbol(); 1499 1500 clearList(Relocations); 1501 1502 if (!IsSimple) { 1503 clearList(Instructions); 1504 return createNonFatalBOLTError(""); 1505 } 1506 1507 updateState(State::Disassembled); 1508 1509 return Error::success(); 1510 } 1511 1512 MCSymbol *BinaryFunction::registerBranch(uint64_t Src, uint64_t Dst) { 1513 assert(CurrentState == State::Disassembled && 1514 "Cannot register branch unless function is in disassembled state."); 1515 assert(containsAddress(Src) && containsAddress(Dst) && 1516 "Cannot register external branch."); 1517 MCSymbol *Target = getOrCreateLocalLabel(Dst); 1518 TakenBranches.emplace_back(Src - getAddress(), Dst - getAddress()); 1519 return Target; 1520 } 1521 1522 bool BinaryFunction::scanExternalRefs() { 1523 bool Success = true; 1524 bool DisassemblyFailed = false; 1525 1526 // Ignore pseudo functions. 1527 if (isPseudo()) 1528 return Success; 1529 1530 if (opts::NoScan) { 1531 clearList(Relocations); 1532 clearList(ExternallyReferencedOffsets); 1533 1534 return false; 1535 } 1536 1537 // List of external references for this function. 1538 std::vector<Relocation> FunctionRelocations; 1539 1540 static BinaryContext::IndependentCodeEmitter Emitter = 1541 BC.createIndependentMCCodeEmitter(); 1542 1543 ErrorOr<ArrayRef<uint8_t>> ErrorOrFunctionData = getData(); 1544 assert(ErrorOrFunctionData && "function data is not available"); 1545 ArrayRef<uint8_t> FunctionData = *ErrorOrFunctionData; 1546 assert(FunctionData.size() == getMaxSize() && 1547 "function size does not match raw data size"); 1548 1549 BC.SymbolicDisAsm->setSymbolizer( 1550 BC.MIB->createTargetSymbolizer(*this, /*CreateSymbols*/ false)); 1551 1552 // Disassemble contents of the function. Detect code entry points and create 1553 // relocations for references to code that will be moved. 1554 uint64_t Size = 0; // instruction size 1555 for (uint64_t Offset = 0; Offset < getSize(); Offset += Size) { 1556 // Check for data inside code and ignore it 1557 if (const size_t DataInCodeSize = getSizeOfDataInCodeAt(Offset)) { 1558 Size = DataInCodeSize; 1559 continue; 1560 } 1561 1562 const uint64_t AbsoluteInstrAddr = getAddress() + Offset; 1563 MCInst Instruction; 1564 if (!BC.SymbolicDisAsm->getInstruction(Instruction, Size, 1565 FunctionData.slice(Offset), 1566 AbsoluteInstrAddr, nulls())) { 1567 if (opts::Verbosity >= 1 && !isZeroPaddingAt(Offset)) { 1568 BC.errs() 1569 << "BOLT-WARNING: unable to disassemble instruction at offset 0x" 1570 << Twine::utohexstr(Offset) << " (address 0x" 1571 << Twine::utohexstr(AbsoluteInstrAddr) << ") in function " << *this 1572 << '\n'; 1573 } 1574 Success = false; 1575 DisassemblyFailed = true; 1576 break; 1577 } 1578 1579 // Return true if we can skip handling the Target function reference. 1580 auto ignoreFunctionRef = [&](const BinaryFunction &Target) { 1581 if (&Target == this) 1582 return true; 1583 1584 // Note that later we may decide not to emit Target function. In that 1585 // case, we conservatively create references that will be ignored or 1586 // resolved to the same function. 1587 if (!BC.shouldEmit(Target)) 1588 return true; 1589 1590 return false; 1591 }; 1592 1593 // Return true if we can ignore reference to the symbol. 1594 auto ignoreReference = [&](const MCSymbol *TargetSymbol) { 1595 if (!TargetSymbol) 1596 return true; 1597 1598 if (BC.forceSymbolRelocations(TargetSymbol->getName())) 1599 return false; 1600 1601 BinaryFunction *TargetFunction = BC.getFunctionForSymbol(TargetSymbol); 1602 if (!TargetFunction) 1603 return true; 1604 1605 return ignoreFunctionRef(*TargetFunction); 1606 }; 1607 1608 // Handle calls and branches separately as symbolization doesn't work for 1609 // them yet. 1610 MCSymbol *BranchTargetSymbol = nullptr; 1611 if (BC.MIB->isCall(Instruction) || BC.MIB->isBranch(Instruction)) { 1612 uint64_t TargetAddress = 0; 1613 BC.MIB->evaluateBranch(Instruction, AbsoluteInstrAddr, Size, 1614 TargetAddress); 1615 1616 // Create an entry point at reference address if needed. 1617 BinaryFunction *TargetFunction = 1618 BC.getBinaryFunctionContainingAddress(TargetAddress); 1619 1620 if (!TargetFunction || ignoreFunctionRef(*TargetFunction)) 1621 continue; 1622 1623 const uint64_t FunctionOffset = 1624 TargetAddress - TargetFunction->getAddress(); 1625 BranchTargetSymbol = 1626 FunctionOffset ? TargetFunction->addEntryPointAtOffset(FunctionOffset) 1627 : TargetFunction->getSymbol(); 1628 } 1629 1630 // Can't find more references. Not creating relocations since we are not 1631 // moving code. 1632 if (!BC.HasRelocations) 1633 continue; 1634 1635 if (BranchTargetSymbol) { 1636 BC.MIB->replaceBranchTarget(Instruction, BranchTargetSymbol, 1637 Emitter.LocalCtx.get()); 1638 } else if (!llvm::any_of(Instruction, 1639 [](const MCOperand &Op) { return Op.isExpr(); })) { 1640 // Skip assembly if the instruction may not have any symbolic operands. 1641 continue; 1642 } 1643 1644 // Emit the instruction using temp emitter and generate relocations. 1645 SmallString<256> Code; 1646 SmallVector<MCFixup, 4> Fixups; 1647 Emitter.MCE->encodeInstruction(Instruction, Code, Fixups, *BC.STI); 1648 1649 // Create relocation for every fixup. 1650 for (const MCFixup &Fixup : Fixups) { 1651 std::optional<Relocation> Rel = BC.MIB->createRelocation(Fixup, *BC.MAB); 1652 if (!Rel) { 1653 Success = false; 1654 continue; 1655 } 1656 1657 if (ignoreReference(Rel->Symbol)) 1658 continue; 1659 1660 if (Relocation::getSizeForType(Rel->Type) < 4) { 1661 // If the instruction uses a short form, then we might not be able 1662 // to handle the rewrite without relaxation, and hence cannot reliably 1663 // create an external reference relocation. 1664 Success = false; 1665 continue; 1666 } 1667 Rel->Offset += getAddress() - getOriginSection()->getAddress() + Offset; 1668 FunctionRelocations.push_back(*Rel); 1669 } 1670 1671 if (!Success) 1672 break; 1673 } 1674 1675 // Reset symbolizer for the disassembler. 1676 BC.SymbolicDisAsm->setSymbolizer(nullptr); 1677 1678 // Add relocations unless disassembly failed for this function. 1679 if (!DisassemblyFailed) 1680 for (Relocation &Rel : FunctionRelocations) 1681 getOriginSection()->addPendingRelocation(Rel); 1682 1683 // Inform BinaryContext that this function symbols will not be defined and 1684 // relocations should not be created against them. 1685 if (BC.HasRelocations) { 1686 for (std::pair<const uint32_t, MCSymbol *> &LI : Labels) 1687 BC.UndefinedSymbols.insert(LI.second); 1688 for (MCSymbol *const EndLabel : FunctionEndLabels) 1689 if (EndLabel) 1690 BC.UndefinedSymbols.insert(EndLabel); 1691 } 1692 1693 clearList(Relocations); 1694 clearList(ExternallyReferencedOffsets); 1695 1696 if (Success && BC.HasRelocations) 1697 HasExternalRefRelocations = true; 1698 1699 if (opts::Verbosity >= 1 && !Success) 1700 BC.outs() << "BOLT-INFO: failed to scan refs for " << *this << '\n'; 1701 1702 return Success; 1703 } 1704 1705 void BinaryFunction::postProcessEntryPoints() { 1706 if (!isSimple()) 1707 return; 1708 1709 for (auto &KV : Labels) { 1710 MCSymbol *Label = KV.second; 1711 if (!getSecondaryEntryPointSymbol(Label)) 1712 continue; 1713 1714 // In non-relocation mode there's potentially an external undetectable 1715 // reference to the entry point and hence we cannot move this entry 1716 // point. Optimizing without moving could be difficult. 1717 // In BAT mode, register any known entry points for CFG construction. 1718 if (!BC.HasRelocations && !BC.HasBATSection) 1719 setSimple(false); 1720 1721 const uint32_t Offset = KV.first; 1722 1723 // If we are at Offset 0 and there is no instruction associated with it, 1724 // this means this is an empty function. Just ignore. If we find an 1725 // instruction at this offset, this entry point is valid. 1726 if (!Offset || getInstructionAtOffset(Offset)) 1727 continue; 1728 1729 // On AArch64 there are legitimate reasons to have references past the 1730 // end of the function, e.g. jump tables. 1731 if (BC.isAArch64() && Offset == getSize()) 1732 continue; 1733 1734 BC.errs() << "BOLT-WARNING: reference in the middle of instruction " 1735 "detected in function " 1736 << *this << " at offset 0x" << Twine::utohexstr(Offset) << '\n'; 1737 if (BC.HasRelocations) 1738 setIgnored(); 1739 setSimple(false); 1740 return; 1741 } 1742 } 1743 1744 void BinaryFunction::postProcessJumpTables() { 1745 // Create labels for all entries. 1746 for (auto &JTI : JumpTables) { 1747 JumpTable &JT = *JTI.second; 1748 if (JT.Type == JumpTable::JTT_PIC && opts::JumpTables == JTS_BASIC) { 1749 opts::JumpTables = JTS_MOVE; 1750 BC.outs() << "BOLT-INFO: forcing -jump-tables=move as PIC jump table was " 1751 "detected in function " 1752 << *this << '\n'; 1753 } 1754 const uint64_t BDSize = 1755 BC.getBinaryDataAtAddress(JT.getAddress())->getSize(); 1756 if (!BDSize) { 1757 BC.setBinaryDataSize(JT.getAddress(), JT.getSize()); 1758 } else { 1759 assert(BDSize >= JT.getSize() && 1760 "jump table cannot be larger than the containing object"); 1761 } 1762 if (!JT.Entries.empty()) 1763 continue; 1764 1765 bool HasOneParent = (JT.Parents.size() == 1); 1766 for (uint64_t EntryAddress : JT.EntriesAsAddress) { 1767 // builtin_unreachable does not belong to any function 1768 // Need to handle separately 1769 bool IsBuiltinUnreachable = 1770 llvm::any_of(JT.Parents, [&](const BinaryFunction *Parent) { 1771 return EntryAddress == Parent->getAddress() + Parent->getSize(); 1772 }); 1773 if (IsBuiltinUnreachable) { 1774 MCSymbol *Label = getOrCreateLocalLabel(EntryAddress, true); 1775 JT.Entries.push_back(Label); 1776 continue; 1777 } 1778 // Create a local label for targets that cannot be reached by other 1779 // fragments. Otherwise, create a secondary entry point in the target 1780 // function. 1781 BinaryFunction *TargetBF = 1782 BC.getBinaryFunctionContainingAddress(EntryAddress); 1783 MCSymbol *Label; 1784 if (HasOneParent && TargetBF == this) { 1785 Label = getOrCreateLocalLabel(EntryAddress, true); 1786 } else { 1787 const uint64_t Offset = EntryAddress - TargetBF->getAddress(); 1788 Label = Offset ? TargetBF->addEntryPointAtOffset(Offset) 1789 : TargetBF->getSymbol(); 1790 } 1791 JT.Entries.push_back(Label); 1792 } 1793 } 1794 1795 // Add TakenBranches from JumpTables. 1796 // 1797 // We want to do it after initial processing since we don't know jump tables' 1798 // boundaries until we process them all. 1799 for (auto &JTSite : JTSites) { 1800 const uint64_t JTSiteOffset = JTSite.first; 1801 const uint64_t JTAddress = JTSite.second; 1802 const JumpTable *JT = getJumpTableContainingAddress(JTAddress); 1803 assert(JT && "cannot find jump table for address"); 1804 1805 uint64_t EntryOffset = JTAddress - JT->getAddress(); 1806 while (EntryOffset < JT->getSize()) { 1807 uint64_t EntryAddress = JT->EntriesAsAddress[EntryOffset / JT->EntrySize]; 1808 uint64_t TargetOffset = EntryAddress - getAddress(); 1809 if (TargetOffset < getSize()) { 1810 TakenBranches.emplace_back(JTSiteOffset, TargetOffset); 1811 1812 if (opts::StrictMode) 1813 registerReferencedOffset(TargetOffset); 1814 } 1815 1816 EntryOffset += JT->EntrySize; 1817 1818 // A label at the next entry means the end of this jump table. 1819 if (JT->Labels.count(EntryOffset)) 1820 break; 1821 } 1822 } 1823 clearList(JTSites); 1824 1825 // Conservatively populate all possible destinations for unknown indirect 1826 // branches. 1827 if (opts::StrictMode && hasInternalReference()) { 1828 for (uint64_t Offset : UnknownIndirectBranchOffsets) { 1829 for (uint64_t PossibleDestination : ExternallyReferencedOffsets) { 1830 // Ignore __builtin_unreachable(). 1831 if (PossibleDestination == getSize()) 1832 continue; 1833 TakenBranches.emplace_back(Offset, PossibleDestination); 1834 } 1835 } 1836 } 1837 } 1838 1839 bool BinaryFunction::validateExternallyReferencedOffsets() { 1840 SmallPtrSet<MCSymbol *, 4> JTTargets; 1841 for (const JumpTable *JT : llvm::make_second_range(JumpTables)) 1842 JTTargets.insert(JT->Entries.begin(), JT->Entries.end()); 1843 1844 bool HasUnclaimedReference = false; 1845 for (uint64_t Destination : ExternallyReferencedOffsets) { 1846 // Ignore __builtin_unreachable(). 1847 if (Destination == getSize()) 1848 continue; 1849 // Ignore constant islands 1850 if (isInConstantIsland(Destination + getAddress())) 1851 continue; 1852 1853 if (BinaryBasicBlock *BB = getBasicBlockAtOffset(Destination)) { 1854 // Check if the externally referenced offset is a recognized jump table 1855 // target. 1856 if (JTTargets.contains(BB->getLabel())) 1857 continue; 1858 1859 if (opts::Verbosity >= 1) { 1860 BC.errs() << "BOLT-WARNING: unclaimed data to code reference (possibly " 1861 << "an unrecognized jump table entry) to " << BB->getName() 1862 << " in " << *this << "\n"; 1863 } 1864 auto L = BC.scopeLock(); 1865 addEntryPoint(*BB); 1866 } else { 1867 BC.errs() << "BOLT-WARNING: unknown data to code reference to offset " 1868 << Twine::utohexstr(Destination) << " in " << *this << "\n"; 1869 setIgnored(); 1870 } 1871 HasUnclaimedReference = true; 1872 } 1873 return !HasUnclaimedReference; 1874 } 1875 1876 bool BinaryFunction::postProcessIndirectBranches( 1877 MCPlusBuilder::AllocatorIdTy AllocId) { 1878 auto addUnknownControlFlow = [&](BinaryBasicBlock &BB) { 1879 LLVM_DEBUG(dbgs() << "BOLT-DEBUG: adding unknown control flow in " << *this 1880 << " for " << BB.getName() << "\n"); 1881 HasUnknownControlFlow = true; 1882 BB.removeAllSuccessors(); 1883 for (uint64_t PossibleDestination : ExternallyReferencedOffsets) 1884 if (BinaryBasicBlock *SuccBB = getBasicBlockAtOffset(PossibleDestination)) 1885 BB.addSuccessor(SuccBB); 1886 }; 1887 1888 uint64_t NumIndirectJumps = 0; 1889 MCInst *LastIndirectJump = nullptr; 1890 BinaryBasicBlock *LastIndirectJumpBB = nullptr; 1891 uint64_t LastJT = 0; 1892 uint16_t LastJTIndexReg = BC.MIB->getNoRegister(); 1893 for (BinaryBasicBlock &BB : blocks()) { 1894 for (BinaryBasicBlock::iterator II = BB.begin(); II != BB.end(); ++II) { 1895 MCInst &Instr = *II; 1896 if (!BC.MIB->isIndirectBranch(Instr)) 1897 continue; 1898 1899 // If there's an indirect branch in a single-block function - 1900 // it must be a tail call. 1901 if (BasicBlocks.size() == 1) { 1902 BC.MIB->convertJmpToTailCall(Instr); 1903 return true; 1904 } 1905 1906 ++NumIndirectJumps; 1907 1908 if (opts::StrictMode && !hasInternalReference()) { 1909 BC.MIB->convertJmpToTailCall(Instr); 1910 break; 1911 } 1912 1913 // Validate the tail call or jump table assumptions now that we know 1914 // basic block boundaries. 1915 if (BC.MIB->isTailCall(Instr) || BC.MIB->getJumpTable(Instr)) { 1916 const unsigned PtrSize = BC.AsmInfo->getCodePointerSize(); 1917 MCInst *MemLocInstr; 1918 unsigned BaseRegNum, IndexRegNum; 1919 int64_t DispValue; 1920 const MCExpr *DispExpr; 1921 MCInst *PCRelBaseInstr; 1922 MCInst *FixedEntryLoadInstr; 1923 IndirectBranchType Type = BC.MIB->analyzeIndirectBranch( 1924 Instr, BB.begin(), II, PtrSize, MemLocInstr, BaseRegNum, 1925 IndexRegNum, DispValue, DispExpr, PCRelBaseInstr, 1926 FixedEntryLoadInstr); 1927 if (Type != IndirectBranchType::UNKNOWN || MemLocInstr != nullptr) 1928 continue; 1929 1930 if (!opts::StrictMode) 1931 return false; 1932 1933 if (BC.MIB->isTailCall(Instr)) { 1934 BC.MIB->convertTailCallToJmp(Instr); 1935 } else { 1936 LastIndirectJump = &Instr; 1937 LastIndirectJumpBB = &BB; 1938 LastJT = BC.MIB->getJumpTable(Instr); 1939 LastJTIndexReg = BC.MIB->getJumpTableIndexReg(Instr); 1940 BC.MIB->unsetJumpTable(Instr); 1941 1942 JumpTable *JT = BC.getJumpTableContainingAddress(LastJT); 1943 if (JT->Type == JumpTable::JTT_NORMAL) { 1944 // Invalidating the jump table may also invalidate other jump table 1945 // boundaries. Until we have/need a support for this, mark the 1946 // function as non-simple. 1947 LLVM_DEBUG(dbgs() << "BOLT-DEBUG: rejected jump table reference" 1948 << JT->getName() << " in " << *this << '\n'); 1949 return false; 1950 } 1951 } 1952 1953 addUnknownControlFlow(BB); 1954 continue; 1955 } 1956 1957 // If this block contains an epilogue code and has an indirect branch, 1958 // then most likely it's a tail call. Otherwise, we cannot tell for sure 1959 // what it is and conservatively reject the function's CFG. 1960 bool IsEpilogue = llvm::any_of(BB, [&](const MCInst &Instr) { 1961 return BC.MIB->isLeave(Instr) || BC.MIB->isPop(Instr); 1962 }); 1963 if (IsEpilogue) { 1964 BC.MIB->convertJmpToTailCall(Instr); 1965 BB.removeAllSuccessors(); 1966 continue; 1967 } 1968 1969 if (opts::Verbosity >= 2) { 1970 BC.outs() << "BOLT-INFO: rejected potential indirect tail call in " 1971 << "function " << *this << " in basic block " << BB.getName() 1972 << ".\n"; 1973 LLVM_DEBUG(BC.printInstructions(dbgs(), BB.begin(), BB.end(), 1974 BB.getOffset(), this, true)); 1975 } 1976 1977 if (!opts::StrictMode) 1978 return false; 1979 1980 addUnknownControlFlow(BB); 1981 } 1982 } 1983 1984 if (HasInternalLabelReference) 1985 return false; 1986 1987 // If there's only one jump table, and one indirect jump, and no other 1988 // references, then we should be able to derive the jump table even if we 1989 // fail to match the pattern. 1990 if (HasUnknownControlFlow && NumIndirectJumps == 1 && 1991 JumpTables.size() == 1 && LastIndirectJump && 1992 !BC.getJumpTableContainingAddress(LastJT)->IsSplit) { 1993 LLVM_DEBUG(dbgs() << "BOLT-DEBUG: unsetting unknown control flow in " 1994 << *this << '\n'); 1995 BC.MIB->setJumpTable(*LastIndirectJump, LastJT, LastJTIndexReg, AllocId); 1996 HasUnknownControlFlow = false; 1997 1998 LastIndirectJumpBB->updateJumpTableSuccessors(); 1999 } 2000 2001 // Validate that all data references to function offsets are claimed by 2002 // recognized jump tables. Register externally referenced blocks as entry 2003 // points. 2004 if (!opts::StrictMode && hasInternalReference()) { 2005 if (!validateExternallyReferencedOffsets()) 2006 return false; 2007 } 2008 2009 if (HasUnknownControlFlow && !BC.HasRelocations) 2010 return false; 2011 2012 return true; 2013 } 2014 2015 void BinaryFunction::recomputeLandingPads() { 2016 updateBBIndices(0); 2017 2018 for (BinaryBasicBlock *BB : BasicBlocks) { 2019 BB->LandingPads.clear(); 2020 BB->Throwers.clear(); 2021 } 2022 2023 for (BinaryBasicBlock *BB : BasicBlocks) { 2024 std::unordered_set<const BinaryBasicBlock *> BBLandingPads; 2025 for (MCInst &Instr : *BB) { 2026 if (!BC.MIB->isInvoke(Instr)) 2027 continue; 2028 2029 const std::optional<MCPlus::MCLandingPad> EHInfo = 2030 BC.MIB->getEHInfo(Instr); 2031 if (!EHInfo || !EHInfo->first) 2032 continue; 2033 2034 BinaryBasicBlock *LPBlock = getBasicBlockForLabel(EHInfo->first); 2035 if (!BBLandingPads.count(LPBlock)) { 2036 BBLandingPads.insert(LPBlock); 2037 BB->LandingPads.emplace_back(LPBlock); 2038 LPBlock->Throwers.emplace_back(BB); 2039 } 2040 } 2041 } 2042 } 2043 2044 Error BinaryFunction::buildCFG(MCPlusBuilder::AllocatorIdTy AllocatorId) { 2045 auto &MIB = BC.MIB; 2046 2047 if (!isSimple()) { 2048 assert(!BC.HasRelocations && 2049 "cannot process file with non-simple function in relocs mode"); 2050 return createNonFatalBOLTError(""); 2051 } 2052 2053 if (CurrentState != State::Disassembled) 2054 return createNonFatalBOLTError(""); 2055 2056 assert(BasicBlocks.empty() && "basic block list should be empty"); 2057 assert((Labels.find(getFirstInstructionOffset()) != Labels.end()) && 2058 "first instruction should always have a label"); 2059 2060 // Create basic blocks in the original layout order: 2061 // 2062 // * Every instruction with associated label marks 2063 // the beginning of a basic block. 2064 // * Conditional instruction marks the end of a basic block, 2065 // except when the following instruction is an 2066 // unconditional branch, and the unconditional branch is not 2067 // a destination of another branch. In the latter case, the 2068 // basic block will consist of a single unconditional branch 2069 // (missed "double-jump" optimization). 2070 // 2071 // Created basic blocks are sorted in layout order since they are 2072 // created in the same order as instructions, and instructions are 2073 // sorted by offsets. 2074 BinaryBasicBlock *InsertBB = nullptr; 2075 BinaryBasicBlock *PrevBB = nullptr; 2076 bool IsLastInstrNop = false; 2077 // Offset of the last non-nop instruction. 2078 uint64_t LastInstrOffset = 0; 2079 2080 auto addCFIPlaceholders = [this](uint64_t CFIOffset, 2081 BinaryBasicBlock *InsertBB) { 2082 for (auto FI = OffsetToCFI.lower_bound(CFIOffset), 2083 FE = OffsetToCFI.upper_bound(CFIOffset); 2084 FI != FE; ++FI) { 2085 addCFIPseudo(InsertBB, InsertBB->end(), FI->second); 2086 } 2087 }; 2088 2089 // For profiling purposes we need to save the offset of the last instruction 2090 // in the basic block. 2091 // NOTE: nops always have an Offset annotation. Annotate the last non-nop as 2092 // older profiles ignored nops. 2093 auto updateOffset = [&](uint64_t Offset) { 2094 assert(PrevBB && PrevBB != InsertBB && "invalid previous block"); 2095 MCInst *LastNonNop = nullptr; 2096 for (BinaryBasicBlock::reverse_iterator RII = PrevBB->getLastNonPseudo(), 2097 E = PrevBB->rend(); 2098 RII != E; ++RII) { 2099 if (!BC.MIB->isPseudo(*RII) && !BC.MIB->isNoop(*RII)) { 2100 LastNonNop = &*RII; 2101 break; 2102 } 2103 } 2104 if (LastNonNop && !MIB->getOffset(*LastNonNop)) 2105 MIB->setOffset(*LastNonNop, static_cast<uint32_t>(Offset)); 2106 }; 2107 2108 for (auto I = Instructions.begin(), E = Instructions.end(); I != E; ++I) { 2109 const uint32_t Offset = I->first; 2110 MCInst &Instr = I->second; 2111 2112 auto LI = Labels.find(Offset); 2113 if (LI != Labels.end()) { 2114 // Always create new BB at branch destination. 2115 PrevBB = InsertBB ? InsertBB : PrevBB; 2116 InsertBB = addBasicBlockAt(LI->first, LI->second); 2117 if (opts::PreserveBlocksAlignment && IsLastInstrNop) 2118 InsertBB->setDerivedAlignment(); 2119 2120 if (PrevBB) 2121 updateOffset(LastInstrOffset); 2122 } 2123 2124 // Mark all nops with Offset for profile tracking purposes. 2125 if (MIB->isNoop(Instr) && !MIB->getOffset(Instr)) { 2126 // If "Offset" annotation is not present, set it and mark the nop for 2127 // deletion. 2128 MIB->setOffset(Instr, static_cast<uint32_t>(Offset)); 2129 // Annotate ordinary nops, so we can safely delete them if required. 2130 MIB->addAnnotation(Instr, "NOP", static_cast<uint32_t>(1), AllocatorId); 2131 } 2132 2133 if (!InsertBB) { 2134 // It must be a fallthrough or unreachable code. Create a new block unless 2135 // we see an unconditional branch following a conditional one. The latter 2136 // should not be a conditional tail call. 2137 assert(PrevBB && "no previous basic block for a fall through"); 2138 MCInst *PrevInstr = PrevBB->getLastNonPseudoInstr(); 2139 assert(PrevInstr && "no previous instruction for a fall through"); 2140 if (MIB->isUnconditionalBranch(Instr) && 2141 !MIB->isIndirectBranch(*PrevInstr) && 2142 !MIB->isUnconditionalBranch(*PrevInstr) && 2143 !MIB->getConditionalTailCall(*PrevInstr) && 2144 !MIB->isReturn(*PrevInstr)) { 2145 // Temporarily restore inserter basic block. 2146 InsertBB = PrevBB; 2147 } else { 2148 MCSymbol *Label; 2149 { 2150 auto L = BC.scopeLock(); 2151 Label = BC.Ctx->createNamedTempSymbol("FT"); 2152 } 2153 InsertBB = addBasicBlockAt(Offset, Label); 2154 if (opts::PreserveBlocksAlignment && IsLastInstrNop) 2155 InsertBB->setDerivedAlignment(); 2156 updateOffset(LastInstrOffset); 2157 } 2158 } 2159 if (Offset == getFirstInstructionOffset()) { 2160 // Add associated CFI pseudos in the first offset 2161 addCFIPlaceholders(Offset, InsertBB); 2162 } 2163 2164 const bool IsBlockEnd = MIB->isTerminator(Instr); 2165 IsLastInstrNop = MIB->isNoop(Instr); 2166 if (!IsLastInstrNop) 2167 LastInstrOffset = Offset; 2168 InsertBB->addInstruction(std::move(Instr)); 2169 2170 // Add associated CFI instrs. We always add the CFI instruction that is 2171 // located immediately after this instruction, since the next CFI 2172 // instruction reflects the change in state caused by this instruction. 2173 auto NextInstr = std::next(I); 2174 uint64_t CFIOffset; 2175 if (NextInstr != E) 2176 CFIOffset = NextInstr->first; 2177 else 2178 CFIOffset = getSize(); 2179 2180 // Note: this potentially invalidates instruction pointers/iterators. 2181 addCFIPlaceholders(CFIOffset, InsertBB); 2182 2183 if (IsBlockEnd) { 2184 PrevBB = InsertBB; 2185 InsertBB = nullptr; 2186 } 2187 } 2188 2189 if (BasicBlocks.empty()) { 2190 setSimple(false); 2191 return createNonFatalBOLTError(""); 2192 } 2193 2194 // Intermediate dump. 2195 LLVM_DEBUG(print(dbgs(), "after creating basic blocks")); 2196 2197 // TODO: handle properly calls to no-return functions, 2198 // e.g. exit(3), etc. Otherwise we'll see a false fall-through 2199 // blocks. 2200 2201 // Remove duplicates branches. We can get a bunch of them from jump tables. 2202 // Without doing jump table value profiling we don't have a use for extra 2203 // (duplicate) branches. 2204 llvm::sort(TakenBranches); 2205 auto NewEnd = std::unique(TakenBranches.begin(), TakenBranches.end()); 2206 TakenBranches.erase(NewEnd, TakenBranches.end()); 2207 2208 for (std::pair<uint32_t, uint32_t> &Branch : TakenBranches) { 2209 LLVM_DEBUG(dbgs() << "registering branch [0x" 2210 << Twine::utohexstr(Branch.first) << "] -> [0x" 2211 << Twine::utohexstr(Branch.second) << "]\n"); 2212 BinaryBasicBlock *FromBB = getBasicBlockContainingOffset(Branch.first); 2213 BinaryBasicBlock *ToBB = getBasicBlockAtOffset(Branch.second); 2214 if (!FromBB || !ToBB) { 2215 if (!FromBB) 2216 BC.errs() << "BOLT-ERROR: cannot find BB containing the branch.\n"; 2217 if (!ToBB) 2218 BC.errs() 2219 << "BOLT-ERROR: cannot find BB containing branch destination.\n"; 2220 return createFatalBOLTError(BC.generateBugReportMessage( 2221 "disassembly failed - inconsistent branch found.", *this)); 2222 } 2223 2224 FromBB->addSuccessor(ToBB); 2225 } 2226 2227 // Add fall-through branches. 2228 PrevBB = nullptr; 2229 bool IsPrevFT = false; // Is previous block a fall-through. 2230 for (BinaryBasicBlock *BB : BasicBlocks) { 2231 if (IsPrevFT) 2232 PrevBB->addSuccessor(BB); 2233 2234 if (BB->empty()) { 2235 IsPrevFT = true; 2236 PrevBB = BB; 2237 continue; 2238 } 2239 2240 MCInst *LastInstr = BB->getLastNonPseudoInstr(); 2241 assert(LastInstr && 2242 "should have non-pseudo instruction in non-empty block"); 2243 2244 if (BB->succ_size() == 0) { 2245 // Since there's no existing successors, we know the last instruction is 2246 // not a conditional branch. Thus if it's a terminator, it shouldn't be a 2247 // fall-through. 2248 // 2249 // Conditional tail call is a special case since we don't add a taken 2250 // branch successor for it. 2251 IsPrevFT = !MIB->isTerminator(*LastInstr) || 2252 MIB->getConditionalTailCall(*LastInstr); 2253 } else if (BB->succ_size() == 1) { 2254 IsPrevFT = MIB->isConditionalBranch(*LastInstr); 2255 } else { 2256 IsPrevFT = false; 2257 } 2258 2259 PrevBB = BB; 2260 } 2261 2262 // Assign landing pads and throwers info. 2263 recomputeLandingPads(); 2264 2265 // Assign CFI information to each BB entry. 2266 annotateCFIState(); 2267 2268 // Annotate invoke instructions with GNU_args_size data. 2269 propagateGnuArgsSizeInfo(AllocatorId); 2270 2271 // Set the basic block layout to the original order and set end offsets. 2272 PrevBB = nullptr; 2273 for (BinaryBasicBlock *BB : BasicBlocks) { 2274 Layout.addBasicBlock(BB); 2275 if (PrevBB) 2276 PrevBB->setEndOffset(BB->getOffset()); 2277 PrevBB = BB; 2278 } 2279 PrevBB->setEndOffset(getSize()); 2280 2281 Layout.updateLayoutIndices(); 2282 2283 normalizeCFIState(); 2284 2285 // Clean-up memory taken by intermediate structures. 2286 // 2287 // NB: don't clear Labels list as we may need them if we mark the function 2288 // as non-simple later in the process of discovering extra entry points. 2289 clearList(Instructions); 2290 clearList(OffsetToCFI); 2291 clearList(TakenBranches); 2292 2293 // Update the state. 2294 CurrentState = State::CFG; 2295 2296 // Make any necessary adjustments for indirect branches. 2297 if (!postProcessIndirectBranches(AllocatorId)) { 2298 if (opts::Verbosity) { 2299 BC.errs() << "BOLT-WARNING: failed to post-process indirect branches for " 2300 << *this << '\n'; 2301 } 2302 // In relocation mode we want to keep processing the function but avoid 2303 // optimizing it. 2304 setSimple(false); 2305 } 2306 2307 clearList(ExternallyReferencedOffsets); 2308 clearList(UnknownIndirectBranchOffsets); 2309 2310 return Error::success(); 2311 } 2312 2313 void BinaryFunction::postProcessCFG() { 2314 if (isSimple() && !BasicBlocks.empty()) { 2315 // Convert conditional tail call branches to conditional branches that jump 2316 // to a tail call. 2317 removeConditionalTailCalls(); 2318 2319 postProcessProfile(); 2320 2321 // Eliminate inconsistencies between branch instructions and CFG. 2322 postProcessBranches(); 2323 } 2324 2325 // The final cleanup of intermediate structures. 2326 clearList(IgnoredBranches); 2327 2328 // Remove "Offset" annotations, unless we need an address-translation table 2329 // later. This has no cost, since annotations are allocated by a bumpptr 2330 // allocator and won't be released anyway until late in the pipeline. 2331 if (!requiresAddressTranslation() && !opts::Instrument) { 2332 for (BinaryBasicBlock &BB : blocks()) 2333 for (MCInst &Inst : BB) 2334 BC.MIB->clearOffset(Inst); 2335 } 2336 2337 assert((!isSimple() || validateCFG()) && 2338 "invalid CFG detected after post-processing"); 2339 } 2340 2341 void BinaryFunction::removeTagsFromProfile() { 2342 for (BinaryBasicBlock *BB : BasicBlocks) { 2343 if (BB->ExecutionCount == BinaryBasicBlock::COUNT_NO_PROFILE) 2344 BB->ExecutionCount = 0; 2345 for (BinaryBasicBlock::BinaryBranchInfo &BI : BB->branch_info()) { 2346 if (BI.Count != BinaryBasicBlock::COUNT_NO_PROFILE && 2347 BI.MispredictedCount != BinaryBasicBlock::COUNT_NO_PROFILE) 2348 continue; 2349 BI.Count = 0; 2350 BI.MispredictedCount = 0; 2351 } 2352 } 2353 } 2354 2355 void BinaryFunction::removeConditionalTailCalls() { 2356 // Blocks to be appended at the end. 2357 std::vector<std::unique_ptr<BinaryBasicBlock>> NewBlocks; 2358 2359 for (auto BBI = begin(); BBI != end(); ++BBI) { 2360 BinaryBasicBlock &BB = *BBI; 2361 MCInst *CTCInstr = BB.getLastNonPseudoInstr(); 2362 if (!CTCInstr) 2363 continue; 2364 2365 std::optional<uint64_t> TargetAddressOrNone = 2366 BC.MIB->getConditionalTailCall(*CTCInstr); 2367 if (!TargetAddressOrNone) 2368 continue; 2369 2370 // Gather all necessary information about CTC instruction before 2371 // annotations are destroyed. 2372 const int32_t CFIStateBeforeCTC = BB.getCFIStateAtInstr(CTCInstr); 2373 uint64_t CTCTakenCount = BinaryBasicBlock::COUNT_NO_PROFILE; 2374 uint64_t CTCMispredCount = BinaryBasicBlock::COUNT_NO_PROFILE; 2375 if (hasValidProfile()) { 2376 CTCTakenCount = BC.MIB->getAnnotationWithDefault<uint64_t>( 2377 *CTCInstr, "CTCTakenCount"); 2378 CTCMispredCount = BC.MIB->getAnnotationWithDefault<uint64_t>( 2379 *CTCInstr, "CTCMispredCount"); 2380 } 2381 2382 // Assert that the tail call does not throw. 2383 assert(!BC.MIB->getEHInfo(*CTCInstr) && 2384 "found tail call with associated landing pad"); 2385 2386 // Create a basic block with an unconditional tail call instruction using 2387 // the same destination. 2388 const MCSymbol *CTCTargetLabel = BC.MIB->getTargetSymbol(*CTCInstr); 2389 assert(CTCTargetLabel && "symbol expected for conditional tail call"); 2390 MCInst TailCallInstr; 2391 BC.MIB->createTailCall(TailCallInstr, CTCTargetLabel, BC.Ctx.get()); 2392 2393 // Move offset from CTCInstr to TailCallInstr. 2394 if (const std::optional<uint32_t> Offset = BC.MIB->getOffset(*CTCInstr)) { 2395 BC.MIB->setOffset(TailCallInstr, *Offset); 2396 BC.MIB->clearOffset(*CTCInstr); 2397 } 2398 2399 // Link new BBs to the original input offset of the BB where the CTC 2400 // is, so we can map samples recorded in new BBs back to the original BB 2401 // seem in the input binary (if using BAT) 2402 std::unique_ptr<BinaryBasicBlock> TailCallBB = 2403 createBasicBlock(BC.Ctx->createNamedTempSymbol("TC")); 2404 TailCallBB->setOffset(BB.getInputOffset()); 2405 TailCallBB->addInstruction(TailCallInstr); 2406 TailCallBB->setCFIState(CFIStateBeforeCTC); 2407 2408 // Add CFG edge with profile info from BB to TailCallBB. 2409 BB.addSuccessor(TailCallBB.get(), CTCTakenCount, CTCMispredCount); 2410 2411 // Add execution count for the block. 2412 TailCallBB->setExecutionCount(CTCTakenCount); 2413 2414 BC.MIB->convertTailCallToJmp(*CTCInstr); 2415 2416 BC.MIB->replaceBranchTarget(*CTCInstr, TailCallBB->getLabel(), 2417 BC.Ctx.get()); 2418 2419 // Add basic block to the list that will be added to the end. 2420 NewBlocks.emplace_back(std::move(TailCallBB)); 2421 2422 // Swap edges as the TailCallBB corresponds to the taken branch. 2423 BB.swapConditionalSuccessors(); 2424 2425 // This branch is no longer a conditional tail call. 2426 BC.MIB->unsetConditionalTailCall(*CTCInstr); 2427 } 2428 2429 insertBasicBlocks(std::prev(end()), std::move(NewBlocks), 2430 /* UpdateLayout */ true, 2431 /* UpdateCFIState */ false); 2432 } 2433 2434 uint64_t BinaryFunction::getFunctionScore() const { 2435 if (FunctionScore != -1) 2436 return FunctionScore; 2437 2438 if (!isSimple() || !hasValidProfile()) { 2439 FunctionScore = 0; 2440 return FunctionScore; 2441 } 2442 2443 uint64_t TotalScore = 0ULL; 2444 for (const BinaryBasicBlock &BB : blocks()) { 2445 uint64_t BBExecCount = BB.getExecutionCount(); 2446 if (BBExecCount == BinaryBasicBlock::COUNT_NO_PROFILE) 2447 continue; 2448 TotalScore += BBExecCount * BB.getNumNonPseudos(); 2449 } 2450 FunctionScore = TotalScore; 2451 return FunctionScore; 2452 } 2453 2454 void BinaryFunction::annotateCFIState() { 2455 assert(CurrentState == State::Disassembled && "unexpected function state"); 2456 assert(!BasicBlocks.empty() && "basic block list should not be empty"); 2457 2458 // This is an index of the last processed CFI in FDE CFI program. 2459 uint32_t State = 0; 2460 2461 // This is an index of RememberState CFI reflecting effective state right 2462 // after execution of RestoreState CFI. 2463 // 2464 // It differs from State iff the CFI at (State-1) 2465 // was RestoreState (modulo GNU_args_size CFIs, which are ignored). 2466 // 2467 // This allows us to generate shorter replay sequences when producing new 2468 // CFI programs. 2469 uint32_t EffectiveState = 0; 2470 2471 // For tracking RememberState/RestoreState sequences. 2472 std::stack<uint32_t> StateStack; 2473 2474 for (BinaryBasicBlock *BB : BasicBlocks) { 2475 BB->setCFIState(EffectiveState); 2476 2477 for (const MCInst &Instr : *BB) { 2478 const MCCFIInstruction *CFI = getCFIFor(Instr); 2479 if (!CFI) 2480 continue; 2481 2482 ++State; 2483 2484 switch (CFI->getOperation()) { 2485 case MCCFIInstruction::OpRememberState: 2486 StateStack.push(EffectiveState); 2487 EffectiveState = State; 2488 break; 2489 case MCCFIInstruction::OpRestoreState: 2490 assert(!StateStack.empty() && "corrupt CFI stack"); 2491 EffectiveState = StateStack.top(); 2492 StateStack.pop(); 2493 break; 2494 case MCCFIInstruction::OpGnuArgsSize: 2495 // OpGnuArgsSize CFIs do not affect the CFI state. 2496 break; 2497 default: 2498 // Any other CFI updates the state. 2499 EffectiveState = State; 2500 break; 2501 } 2502 } 2503 } 2504 2505 if (opts::Verbosity >= 1 && !StateStack.empty()) { 2506 BC.errs() << "BOLT-WARNING: non-empty CFI stack at the end of " << *this 2507 << '\n'; 2508 } 2509 } 2510 2511 namespace { 2512 2513 /// Our full interpretation of a DWARF CFI machine state at a given point 2514 struct CFISnapshot { 2515 /// CFA register number and offset defining the canonical frame at this 2516 /// point, or the number of a rule (CFI state) that computes it with a 2517 /// DWARF expression. This number will be negative if it refers to a CFI 2518 /// located in the CIE instead of the FDE. 2519 uint32_t CFAReg; 2520 int32_t CFAOffset; 2521 int32_t CFARule; 2522 /// Mapping of rules (CFI states) that define the location of each 2523 /// register. If absent, no rule defining the location of such register 2524 /// was ever read. This number will be negative if it refers to a CFI 2525 /// located in the CIE instead of the FDE. 2526 DenseMap<int32_t, int32_t> RegRule; 2527 2528 /// References to CIE, FDE and expanded instructions after a restore state 2529 const BinaryFunction::CFIInstrMapType &CIE; 2530 const BinaryFunction::CFIInstrMapType &FDE; 2531 const DenseMap<int32_t, SmallVector<int32_t, 4>> &FrameRestoreEquivalents; 2532 2533 /// Current FDE CFI number representing the state where the snapshot is at 2534 int32_t CurState; 2535 2536 /// Used when we don't have information about which state/rule to apply 2537 /// to recover the location of either the CFA or a specific register 2538 constexpr static int32_t UNKNOWN = std::numeric_limits<int32_t>::min(); 2539 2540 private: 2541 /// Update our snapshot by executing a single CFI 2542 void update(const MCCFIInstruction &Instr, int32_t RuleNumber) { 2543 switch (Instr.getOperation()) { 2544 case MCCFIInstruction::OpSameValue: 2545 case MCCFIInstruction::OpRelOffset: 2546 case MCCFIInstruction::OpOffset: 2547 case MCCFIInstruction::OpRestore: 2548 case MCCFIInstruction::OpUndefined: 2549 case MCCFIInstruction::OpRegister: 2550 RegRule[Instr.getRegister()] = RuleNumber; 2551 break; 2552 case MCCFIInstruction::OpDefCfaRegister: 2553 CFAReg = Instr.getRegister(); 2554 CFARule = UNKNOWN; 2555 2556 // This shouldn't happen according to the spec but GNU binutils on RISC-V 2557 // emits a DW_CFA_def_cfa_register in CIE's which leaves the offset 2558 // unspecified. Both readelf and llvm-dwarfdump interpret the offset as 0 2559 // in this case so let's do the same. 2560 if (CFAOffset == UNKNOWN) 2561 CFAOffset = 0; 2562 break; 2563 case MCCFIInstruction::OpDefCfaOffset: 2564 CFAOffset = Instr.getOffset(); 2565 CFARule = UNKNOWN; 2566 break; 2567 case MCCFIInstruction::OpDefCfa: 2568 CFAReg = Instr.getRegister(); 2569 CFAOffset = Instr.getOffset(); 2570 CFARule = UNKNOWN; 2571 break; 2572 case MCCFIInstruction::OpEscape: { 2573 std::optional<uint8_t> Reg = 2574 readDWARFExpressionTargetReg(Instr.getValues()); 2575 // Handle DW_CFA_def_cfa_expression 2576 if (!Reg) { 2577 CFARule = RuleNumber; 2578 break; 2579 } 2580 RegRule[*Reg] = RuleNumber; 2581 break; 2582 } 2583 case MCCFIInstruction::OpAdjustCfaOffset: 2584 case MCCFIInstruction::OpWindowSave: 2585 case MCCFIInstruction::OpNegateRAState: 2586 case MCCFIInstruction::OpLLVMDefAspaceCfa: 2587 case MCCFIInstruction::OpLabel: 2588 llvm_unreachable("unsupported CFI opcode"); 2589 break; 2590 case MCCFIInstruction::OpRememberState: 2591 case MCCFIInstruction::OpRestoreState: 2592 case MCCFIInstruction::OpGnuArgsSize: 2593 // do not affect CFI state 2594 break; 2595 } 2596 } 2597 2598 public: 2599 /// Advance state reading FDE CFI instructions up to State number 2600 void advanceTo(int32_t State) { 2601 for (int32_t I = CurState, E = State; I != E; ++I) { 2602 const MCCFIInstruction &Instr = FDE[I]; 2603 if (Instr.getOperation() != MCCFIInstruction::OpRestoreState) { 2604 update(Instr, I); 2605 continue; 2606 } 2607 // If restore state instruction, fetch the equivalent CFIs that have 2608 // the same effect of this restore. This is used to ensure remember- 2609 // restore pairs are completely removed. 2610 auto Iter = FrameRestoreEquivalents.find(I); 2611 if (Iter == FrameRestoreEquivalents.end()) 2612 continue; 2613 for (int32_t RuleNumber : Iter->second) 2614 update(FDE[RuleNumber], RuleNumber); 2615 } 2616 2617 assert(((CFAReg != (uint32_t)UNKNOWN && CFAOffset != UNKNOWN) || 2618 CFARule != UNKNOWN) && 2619 "CIE did not define default CFA?"); 2620 2621 CurState = State; 2622 } 2623 2624 /// Interpret all CIE and FDE instructions up until CFI State number and 2625 /// populate this snapshot 2626 CFISnapshot( 2627 const BinaryFunction::CFIInstrMapType &CIE, 2628 const BinaryFunction::CFIInstrMapType &FDE, 2629 const DenseMap<int32_t, SmallVector<int32_t, 4>> &FrameRestoreEquivalents, 2630 int32_t State) 2631 : CIE(CIE), FDE(FDE), FrameRestoreEquivalents(FrameRestoreEquivalents) { 2632 CFAReg = UNKNOWN; 2633 CFAOffset = UNKNOWN; 2634 CFARule = UNKNOWN; 2635 CurState = 0; 2636 2637 for (int32_t I = 0, E = CIE.size(); I != E; ++I) { 2638 const MCCFIInstruction &Instr = CIE[I]; 2639 update(Instr, -I); 2640 } 2641 2642 advanceTo(State); 2643 } 2644 }; 2645 2646 /// A CFI snapshot with the capability of checking if incremental additions to 2647 /// it are redundant. This is used to ensure we do not emit two CFI instructions 2648 /// back-to-back that are doing the same state change, or to avoid emitting a 2649 /// CFI at all when the state at that point would not be modified after that CFI 2650 struct CFISnapshotDiff : public CFISnapshot { 2651 bool RestoredCFAReg{false}; 2652 bool RestoredCFAOffset{false}; 2653 DenseMap<int32_t, bool> RestoredRegs; 2654 2655 CFISnapshotDiff(const CFISnapshot &S) : CFISnapshot(S) {} 2656 2657 CFISnapshotDiff( 2658 const BinaryFunction::CFIInstrMapType &CIE, 2659 const BinaryFunction::CFIInstrMapType &FDE, 2660 const DenseMap<int32_t, SmallVector<int32_t, 4>> &FrameRestoreEquivalents, 2661 int32_t State) 2662 : CFISnapshot(CIE, FDE, FrameRestoreEquivalents, State) {} 2663 2664 /// Return true if applying Instr to this state is redundant and can be 2665 /// dismissed. 2666 bool isRedundant(const MCCFIInstruction &Instr) { 2667 switch (Instr.getOperation()) { 2668 case MCCFIInstruction::OpSameValue: 2669 case MCCFIInstruction::OpRelOffset: 2670 case MCCFIInstruction::OpOffset: 2671 case MCCFIInstruction::OpRestore: 2672 case MCCFIInstruction::OpUndefined: 2673 case MCCFIInstruction::OpRegister: 2674 case MCCFIInstruction::OpEscape: { 2675 uint32_t Reg; 2676 if (Instr.getOperation() != MCCFIInstruction::OpEscape) { 2677 Reg = Instr.getRegister(); 2678 } else { 2679 std::optional<uint8_t> R = 2680 readDWARFExpressionTargetReg(Instr.getValues()); 2681 // Handle DW_CFA_def_cfa_expression 2682 if (!R) { 2683 if (RestoredCFAReg && RestoredCFAOffset) 2684 return true; 2685 RestoredCFAReg = true; 2686 RestoredCFAOffset = true; 2687 return false; 2688 } 2689 Reg = *R; 2690 } 2691 if (RestoredRegs[Reg]) 2692 return true; 2693 RestoredRegs[Reg] = true; 2694 const int32_t CurRegRule = RegRule.contains(Reg) ? RegRule[Reg] : UNKNOWN; 2695 if (CurRegRule == UNKNOWN) { 2696 if (Instr.getOperation() == MCCFIInstruction::OpRestore || 2697 Instr.getOperation() == MCCFIInstruction::OpSameValue) 2698 return true; 2699 return false; 2700 } 2701 const MCCFIInstruction &LastDef = 2702 CurRegRule < 0 ? CIE[-CurRegRule] : FDE[CurRegRule]; 2703 return LastDef == Instr; 2704 } 2705 case MCCFIInstruction::OpDefCfaRegister: 2706 if (RestoredCFAReg) 2707 return true; 2708 RestoredCFAReg = true; 2709 return CFAReg == Instr.getRegister(); 2710 case MCCFIInstruction::OpDefCfaOffset: 2711 if (RestoredCFAOffset) 2712 return true; 2713 RestoredCFAOffset = true; 2714 return CFAOffset == Instr.getOffset(); 2715 case MCCFIInstruction::OpDefCfa: 2716 if (RestoredCFAReg && RestoredCFAOffset) 2717 return true; 2718 RestoredCFAReg = true; 2719 RestoredCFAOffset = true; 2720 return CFAReg == Instr.getRegister() && CFAOffset == Instr.getOffset(); 2721 case MCCFIInstruction::OpAdjustCfaOffset: 2722 case MCCFIInstruction::OpWindowSave: 2723 case MCCFIInstruction::OpNegateRAState: 2724 case MCCFIInstruction::OpLLVMDefAspaceCfa: 2725 case MCCFIInstruction::OpLabel: 2726 llvm_unreachable("unsupported CFI opcode"); 2727 return false; 2728 case MCCFIInstruction::OpRememberState: 2729 case MCCFIInstruction::OpRestoreState: 2730 case MCCFIInstruction::OpGnuArgsSize: 2731 // do not affect CFI state 2732 return true; 2733 } 2734 return false; 2735 } 2736 }; 2737 2738 } // end anonymous namespace 2739 2740 bool BinaryFunction::replayCFIInstrs(int32_t FromState, int32_t ToState, 2741 BinaryBasicBlock *InBB, 2742 BinaryBasicBlock::iterator InsertIt) { 2743 if (FromState == ToState) 2744 return true; 2745 assert(FromState < ToState && "can only replay CFIs forward"); 2746 2747 CFISnapshotDiff CFIDiff(CIEFrameInstructions, FrameInstructions, 2748 FrameRestoreEquivalents, FromState); 2749 2750 std::vector<uint32_t> NewCFIs; 2751 for (int32_t CurState = FromState; CurState < ToState; ++CurState) { 2752 MCCFIInstruction *Instr = &FrameInstructions[CurState]; 2753 if (Instr->getOperation() == MCCFIInstruction::OpRestoreState) { 2754 auto Iter = FrameRestoreEquivalents.find(CurState); 2755 assert(Iter != FrameRestoreEquivalents.end()); 2756 NewCFIs.insert(NewCFIs.end(), Iter->second.begin(), Iter->second.end()); 2757 // RestoreState / Remember will be filtered out later by CFISnapshotDiff, 2758 // so we might as well fall-through here. 2759 } 2760 NewCFIs.push_back(CurState); 2761 } 2762 2763 // Replay instructions while avoiding duplicates 2764 for (int32_t State : llvm::reverse(NewCFIs)) { 2765 if (CFIDiff.isRedundant(FrameInstructions[State])) 2766 continue; 2767 InsertIt = addCFIPseudo(InBB, InsertIt, State); 2768 } 2769 2770 return true; 2771 } 2772 2773 SmallVector<int32_t, 4> 2774 BinaryFunction::unwindCFIState(int32_t FromState, int32_t ToState, 2775 BinaryBasicBlock *InBB, 2776 BinaryBasicBlock::iterator &InsertIt) { 2777 SmallVector<int32_t, 4> NewStates; 2778 2779 CFISnapshot ToCFITable(CIEFrameInstructions, FrameInstructions, 2780 FrameRestoreEquivalents, ToState); 2781 CFISnapshotDiff FromCFITable(ToCFITable); 2782 FromCFITable.advanceTo(FromState); 2783 2784 auto undoStateDefCfa = [&]() { 2785 if (ToCFITable.CFARule == CFISnapshot::UNKNOWN) { 2786 FrameInstructions.emplace_back(MCCFIInstruction::cfiDefCfa( 2787 nullptr, ToCFITable.CFAReg, ToCFITable.CFAOffset)); 2788 if (FromCFITable.isRedundant(FrameInstructions.back())) { 2789 FrameInstructions.pop_back(); 2790 return; 2791 } 2792 NewStates.push_back(FrameInstructions.size() - 1); 2793 InsertIt = addCFIPseudo(InBB, InsertIt, FrameInstructions.size() - 1); 2794 ++InsertIt; 2795 } else if (ToCFITable.CFARule < 0) { 2796 if (FromCFITable.isRedundant(CIEFrameInstructions[-ToCFITable.CFARule])) 2797 return; 2798 NewStates.push_back(FrameInstructions.size()); 2799 InsertIt = addCFIPseudo(InBB, InsertIt, FrameInstructions.size()); 2800 ++InsertIt; 2801 FrameInstructions.emplace_back(CIEFrameInstructions[-ToCFITable.CFARule]); 2802 } else if (!FromCFITable.isRedundant( 2803 FrameInstructions[ToCFITable.CFARule])) { 2804 NewStates.push_back(ToCFITable.CFARule); 2805 InsertIt = addCFIPseudo(InBB, InsertIt, ToCFITable.CFARule); 2806 ++InsertIt; 2807 } 2808 }; 2809 2810 auto undoState = [&](const MCCFIInstruction &Instr) { 2811 switch (Instr.getOperation()) { 2812 case MCCFIInstruction::OpRememberState: 2813 case MCCFIInstruction::OpRestoreState: 2814 break; 2815 case MCCFIInstruction::OpSameValue: 2816 case MCCFIInstruction::OpRelOffset: 2817 case MCCFIInstruction::OpOffset: 2818 case MCCFIInstruction::OpRestore: 2819 case MCCFIInstruction::OpUndefined: 2820 case MCCFIInstruction::OpEscape: 2821 case MCCFIInstruction::OpRegister: { 2822 uint32_t Reg; 2823 if (Instr.getOperation() != MCCFIInstruction::OpEscape) { 2824 Reg = Instr.getRegister(); 2825 } else { 2826 std::optional<uint8_t> R = 2827 readDWARFExpressionTargetReg(Instr.getValues()); 2828 // Handle DW_CFA_def_cfa_expression 2829 if (!R) { 2830 undoStateDefCfa(); 2831 return; 2832 } 2833 Reg = *R; 2834 } 2835 2836 if (!ToCFITable.RegRule.contains(Reg)) { 2837 FrameInstructions.emplace_back( 2838 MCCFIInstruction::createRestore(nullptr, Reg)); 2839 if (FromCFITable.isRedundant(FrameInstructions.back())) { 2840 FrameInstructions.pop_back(); 2841 break; 2842 } 2843 NewStates.push_back(FrameInstructions.size() - 1); 2844 InsertIt = addCFIPseudo(InBB, InsertIt, FrameInstructions.size() - 1); 2845 ++InsertIt; 2846 break; 2847 } 2848 const int32_t Rule = ToCFITable.RegRule[Reg]; 2849 if (Rule < 0) { 2850 if (FromCFITable.isRedundant(CIEFrameInstructions[-Rule])) 2851 break; 2852 NewStates.push_back(FrameInstructions.size()); 2853 InsertIt = addCFIPseudo(InBB, InsertIt, FrameInstructions.size()); 2854 ++InsertIt; 2855 FrameInstructions.emplace_back(CIEFrameInstructions[-Rule]); 2856 break; 2857 } 2858 if (FromCFITable.isRedundant(FrameInstructions[Rule])) 2859 break; 2860 NewStates.push_back(Rule); 2861 InsertIt = addCFIPseudo(InBB, InsertIt, Rule); 2862 ++InsertIt; 2863 break; 2864 } 2865 case MCCFIInstruction::OpDefCfaRegister: 2866 case MCCFIInstruction::OpDefCfaOffset: 2867 case MCCFIInstruction::OpDefCfa: 2868 undoStateDefCfa(); 2869 break; 2870 case MCCFIInstruction::OpAdjustCfaOffset: 2871 case MCCFIInstruction::OpWindowSave: 2872 case MCCFIInstruction::OpNegateRAState: 2873 case MCCFIInstruction::OpLLVMDefAspaceCfa: 2874 case MCCFIInstruction::OpLabel: 2875 llvm_unreachable("unsupported CFI opcode"); 2876 break; 2877 case MCCFIInstruction::OpGnuArgsSize: 2878 // do not affect CFI state 2879 break; 2880 } 2881 }; 2882 2883 // Undo all modifications from ToState to FromState 2884 for (int32_t I = ToState, E = FromState; I != E; ++I) { 2885 const MCCFIInstruction &Instr = FrameInstructions[I]; 2886 if (Instr.getOperation() != MCCFIInstruction::OpRestoreState) { 2887 undoState(Instr); 2888 continue; 2889 } 2890 auto Iter = FrameRestoreEquivalents.find(I); 2891 if (Iter == FrameRestoreEquivalents.end()) 2892 continue; 2893 for (int32_t State : Iter->second) 2894 undoState(FrameInstructions[State]); 2895 } 2896 2897 return NewStates; 2898 } 2899 2900 void BinaryFunction::normalizeCFIState() { 2901 // Reordering blocks with remember-restore state instructions can be specially 2902 // tricky. When rewriting the CFI, we omit remember-restore state instructions 2903 // entirely. For restore state, we build a map expanding each restore to the 2904 // equivalent unwindCFIState sequence required at that point to achieve the 2905 // same effect of the restore. All remember state are then just ignored. 2906 std::stack<int32_t> Stack; 2907 for (BinaryBasicBlock *CurBB : Layout.blocks()) { 2908 for (auto II = CurBB->begin(); II != CurBB->end(); ++II) { 2909 if (const MCCFIInstruction *CFI = getCFIFor(*II)) { 2910 if (CFI->getOperation() == MCCFIInstruction::OpRememberState) { 2911 Stack.push(II->getOperand(0).getImm()); 2912 continue; 2913 } 2914 if (CFI->getOperation() == MCCFIInstruction::OpRestoreState) { 2915 const int32_t RememberState = Stack.top(); 2916 const int32_t CurState = II->getOperand(0).getImm(); 2917 FrameRestoreEquivalents[CurState] = 2918 unwindCFIState(CurState, RememberState, CurBB, II); 2919 Stack.pop(); 2920 } 2921 } 2922 } 2923 } 2924 } 2925 2926 bool BinaryFunction::finalizeCFIState() { 2927 LLVM_DEBUG( 2928 dbgs() << "Trying to fix CFI states for each BB after reordering.\n"); 2929 LLVM_DEBUG(dbgs() << "This is the list of CFI states for each BB of " << *this 2930 << ": "); 2931 2932 const char *Sep = ""; 2933 (void)Sep; 2934 for (FunctionFragment &FF : Layout.fragments()) { 2935 // Hot-cold border: at start of each region (with a different FDE) we need 2936 // to reset the CFI state. 2937 int32_t State = 0; 2938 2939 for (BinaryBasicBlock *BB : FF) { 2940 const int32_t CFIStateAtExit = BB->getCFIStateAtExit(); 2941 2942 // We need to recover the correct state if it doesn't match expected 2943 // state at BB entry point. 2944 if (BB->getCFIState() < State) { 2945 // In this case, State is currently higher than what this BB expect it 2946 // to be. To solve this, we need to insert CFI instructions to undo 2947 // the effect of all CFI from BB's state to current State. 2948 auto InsertIt = BB->begin(); 2949 unwindCFIState(State, BB->getCFIState(), BB, InsertIt); 2950 } else if (BB->getCFIState() > State) { 2951 // If BB's CFI state is greater than State, it means we are behind in 2952 // the state. Just emit all instructions to reach this state at the 2953 // beginning of this BB. If this sequence of instructions involve 2954 // remember state or restore state, bail out. 2955 if (!replayCFIInstrs(State, BB->getCFIState(), BB, BB->begin())) 2956 return false; 2957 } 2958 2959 State = CFIStateAtExit; 2960 LLVM_DEBUG(dbgs() << Sep << State; Sep = ", "); 2961 } 2962 } 2963 LLVM_DEBUG(dbgs() << "\n"); 2964 2965 for (BinaryBasicBlock &BB : blocks()) { 2966 for (auto II = BB.begin(); II != BB.end();) { 2967 const MCCFIInstruction *CFI = getCFIFor(*II); 2968 if (CFI && (CFI->getOperation() == MCCFIInstruction::OpRememberState || 2969 CFI->getOperation() == MCCFIInstruction::OpRestoreState)) { 2970 II = BB.eraseInstruction(II); 2971 } else { 2972 ++II; 2973 } 2974 } 2975 } 2976 2977 return true; 2978 } 2979 2980 bool BinaryFunction::requiresAddressTranslation() const { 2981 return opts::EnableBAT || hasSDTMarker() || hasPseudoProbe(); 2982 } 2983 2984 bool BinaryFunction::requiresAddressMap() const { 2985 if (isInjected()) 2986 return false; 2987 2988 return opts::UpdateDebugSections || isMultiEntry() || 2989 requiresAddressTranslation(); 2990 } 2991 2992 uint64_t BinaryFunction::getInstructionCount() const { 2993 uint64_t Count = 0; 2994 for (const BinaryBasicBlock &BB : blocks()) 2995 Count += BB.getNumNonPseudos(); 2996 return Count; 2997 } 2998 2999 void BinaryFunction::clearDisasmState() { 3000 clearList(Instructions); 3001 clearList(IgnoredBranches); 3002 clearList(TakenBranches); 3003 3004 if (BC.HasRelocations) { 3005 for (std::pair<const uint32_t, MCSymbol *> &LI : Labels) 3006 BC.UndefinedSymbols.insert(LI.second); 3007 for (MCSymbol *const EndLabel : FunctionEndLabels) 3008 if (EndLabel) 3009 BC.UndefinedSymbols.insert(EndLabel); 3010 } 3011 } 3012 3013 void BinaryFunction::setTrapOnEntry() { 3014 clearDisasmState(); 3015 3016 forEachEntryPoint([&](uint64_t Offset, const MCSymbol *Label) -> bool { 3017 MCInst TrapInstr; 3018 BC.MIB->createTrap(TrapInstr); 3019 addInstruction(Offset, std::move(TrapInstr)); 3020 return true; 3021 }); 3022 3023 TrapsOnEntry = true; 3024 } 3025 3026 void BinaryFunction::setIgnored() { 3027 if (opts::processAllFunctions()) { 3028 // We can accept ignored functions before they've been disassembled. 3029 // In that case, they would still get disassembled and emited, but not 3030 // optimized. 3031 assert(CurrentState == State::Empty && 3032 "cannot ignore non-empty functions in current mode"); 3033 IsIgnored = true; 3034 return; 3035 } 3036 3037 clearDisasmState(); 3038 3039 // Clear CFG state too. 3040 if (hasCFG()) { 3041 releaseCFG(); 3042 3043 for (BinaryBasicBlock *BB : BasicBlocks) 3044 delete BB; 3045 clearList(BasicBlocks); 3046 3047 for (BinaryBasicBlock *BB : DeletedBasicBlocks) 3048 delete BB; 3049 clearList(DeletedBasicBlocks); 3050 3051 Layout.clear(); 3052 } 3053 3054 CurrentState = State::Empty; 3055 3056 IsIgnored = true; 3057 IsSimple = false; 3058 LLVM_DEBUG(dbgs() << "Ignoring " << getPrintName() << '\n'); 3059 } 3060 3061 void BinaryFunction::duplicateConstantIslands() { 3062 assert(Islands && "function expected to have constant islands"); 3063 3064 for (BinaryBasicBlock *BB : getLayout().blocks()) { 3065 if (!BB->isCold()) 3066 continue; 3067 3068 for (MCInst &Inst : *BB) { 3069 int OpNum = 0; 3070 for (MCOperand &Operand : Inst) { 3071 if (!Operand.isExpr()) { 3072 ++OpNum; 3073 continue; 3074 } 3075 const MCSymbol *Symbol = BC.MIB->getTargetSymbol(Inst, OpNum); 3076 // Check if this is an island symbol 3077 if (!Islands->Symbols.count(Symbol) && 3078 !Islands->ProxySymbols.count(Symbol)) 3079 continue; 3080 3081 // Create cold symbol, if missing 3082 auto ISym = Islands->ColdSymbols.find(Symbol); 3083 MCSymbol *ColdSymbol; 3084 if (ISym != Islands->ColdSymbols.end()) { 3085 ColdSymbol = ISym->second; 3086 } else { 3087 ColdSymbol = BC.Ctx->getOrCreateSymbol(Symbol->getName() + ".cold"); 3088 Islands->ColdSymbols[Symbol] = ColdSymbol; 3089 // Check if this is a proxy island symbol and update owner proxy map 3090 if (Islands->ProxySymbols.count(Symbol)) { 3091 BinaryFunction *Owner = Islands->ProxySymbols[Symbol]; 3092 auto IProxiedSym = Owner->Islands->Proxies[this].find(Symbol); 3093 Owner->Islands->ColdProxies[this][IProxiedSym->second] = ColdSymbol; 3094 } 3095 } 3096 3097 // Update instruction reference 3098 Operand = MCOperand::createExpr(BC.MIB->getTargetExprFor( 3099 Inst, 3100 MCSymbolRefExpr::create(ColdSymbol, MCSymbolRefExpr::VK_None, 3101 *BC.Ctx), 3102 *BC.Ctx, 0)); 3103 ++OpNum; 3104 } 3105 } 3106 } 3107 } 3108 3109 #ifndef MAX_PATH 3110 #define MAX_PATH 255 3111 #endif 3112 3113 static std::string constructFilename(std::string Filename, 3114 std::string Annotation, 3115 std::string Suffix) { 3116 std::replace(Filename.begin(), Filename.end(), '/', '-'); 3117 if (!Annotation.empty()) 3118 Annotation.insert(0, "-"); 3119 if (Filename.size() + Annotation.size() + Suffix.size() > MAX_PATH) { 3120 assert(Suffix.size() + Annotation.size() <= MAX_PATH); 3121 Filename.resize(MAX_PATH - (Suffix.size() + Annotation.size())); 3122 } 3123 Filename += Annotation; 3124 Filename += Suffix; 3125 return Filename; 3126 } 3127 3128 static std::string formatEscapes(const std::string &Str) { 3129 std::string Result; 3130 for (unsigned I = 0; I < Str.size(); ++I) { 3131 char C = Str[I]; 3132 switch (C) { 3133 case '\n': 3134 Result += " "; 3135 break; 3136 case '"': 3137 break; 3138 default: 3139 Result += C; 3140 break; 3141 } 3142 } 3143 return Result; 3144 } 3145 3146 void BinaryFunction::dumpGraph(raw_ostream &OS) const { 3147 OS << "digraph \"" << getPrintName() << "\" {\n" 3148 << "node [fontname=courier, shape=box, style=filled, colorscheme=brbg9]\n"; 3149 uint64_t Offset = Address; 3150 for (BinaryBasicBlock *BB : BasicBlocks) { 3151 auto LayoutPos = find(Layout.blocks(), BB); 3152 unsigned LayoutIndex = LayoutPos - Layout.block_begin(); 3153 const char *ColdStr = BB->isCold() ? " (cold)" : ""; 3154 std::vector<std::string> Attrs; 3155 // Bold box for entry points 3156 if (isEntryPoint(*BB)) 3157 Attrs.push_back("penwidth=2"); 3158 if (BLI && BLI->getLoopFor(BB)) { 3159 // Distinguish innermost loops 3160 const BinaryLoop *Loop = BLI->getLoopFor(BB); 3161 if (Loop->isInnermost()) 3162 Attrs.push_back("fillcolor=6"); 3163 else // some outer loop 3164 Attrs.push_back("fillcolor=4"); 3165 } else { // non-loopy code 3166 Attrs.push_back("fillcolor=5"); 3167 } 3168 ListSeparator LS; 3169 OS << "\"" << BB->getName() << "\" ["; 3170 for (StringRef Attr : Attrs) 3171 OS << LS << Attr; 3172 OS << "]\n"; 3173 OS << format("\"%s\" [label=\"%s%s\\n(C:%lu,O:%lu,I:%u,L:%u,CFI:%u)\\n", 3174 BB->getName().data(), BB->getName().data(), ColdStr, 3175 BB->getKnownExecutionCount(), BB->getOffset(), getIndex(BB), 3176 LayoutIndex, BB->getCFIState()); 3177 3178 if (opts::DotToolTipCode) { 3179 std::string Str; 3180 raw_string_ostream CS(Str); 3181 Offset = BC.printInstructions(CS, BB->begin(), BB->end(), Offset, this, 3182 /* PrintMCInst = */ false, 3183 /* PrintMemData = */ false, 3184 /* PrintRelocations = */ false, 3185 /* Endl = */ R"(\\l)"); 3186 OS << formatEscapes(CS.str()) << '\n'; 3187 } 3188 OS << "\"]\n"; 3189 3190 // analyzeBranch is just used to get the names of the branch 3191 // opcodes. 3192 const MCSymbol *TBB = nullptr; 3193 const MCSymbol *FBB = nullptr; 3194 MCInst *CondBranch = nullptr; 3195 MCInst *UncondBranch = nullptr; 3196 const bool Success = BB->analyzeBranch(TBB, FBB, CondBranch, UncondBranch); 3197 3198 const MCInst *LastInstr = BB->getLastNonPseudoInstr(); 3199 const bool IsJumpTable = LastInstr && BC.MIB->getJumpTable(*LastInstr); 3200 3201 auto BI = BB->branch_info_begin(); 3202 for (BinaryBasicBlock *Succ : BB->successors()) { 3203 std::string Branch; 3204 if (Success) { 3205 if (Succ == BB->getConditionalSuccessor(true)) { 3206 Branch = CondBranch ? std::string(BC.InstPrinter->getOpcodeName( 3207 CondBranch->getOpcode())) 3208 : "TB"; 3209 } else if (Succ == BB->getConditionalSuccessor(false)) { 3210 Branch = UncondBranch ? std::string(BC.InstPrinter->getOpcodeName( 3211 UncondBranch->getOpcode())) 3212 : "FB"; 3213 } else { 3214 Branch = "FT"; 3215 } 3216 } 3217 if (IsJumpTable) 3218 Branch = "JT"; 3219 OS << format("\"%s\" -> \"%s\" [label=\"%s", BB->getName().data(), 3220 Succ->getName().data(), Branch.c_str()); 3221 3222 if (BB->getExecutionCount() != COUNT_NO_PROFILE && 3223 BI->MispredictedCount != BinaryBasicBlock::COUNT_INFERRED) { 3224 OS << "\\n(C:" << BI->Count << ",M:" << BI->MispredictedCount << ")"; 3225 } else if (ExecutionCount != COUNT_NO_PROFILE && 3226 BI->Count != BinaryBasicBlock::COUNT_NO_PROFILE) { 3227 OS << "\\n(IC:" << BI->Count << ")"; 3228 } 3229 OS << "\"]\n"; 3230 3231 ++BI; 3232 } 3233 for (BinaryBasicBlock *LP : BB->landing_pads()) { 3234 OS << format("\"%s\" -> \"%s\" [constraint=false style=dashed]\n", 3235 BB->getName().data(), LP->getName().data()); 3236 } 3237 } 3238 OS << "}\n"; 3239 } 3240 3241 void BinaryFunction::viewGraph() const { 3242 SmallString<MAX_PATH> Filename; 3243 if (std::error_code EC = 3244 sys::fs::createTemporaryFile("bolt-cfg", "dot", Filename)) { 3245 BC.errs() << "BOLT-ERROR: " << EC.message() << ", unable to create " 3246 << " bolt-cfg-XXXXX.dot temporary file.\n"; 3247 return; 3248 } 3249 dumpGraphToFile(std::string(Filename)); 3250 if (DisplayGraph(Filename)) 3251 BC.errs() << "BOLT-ERROR: Can't display " << Filename 3252 << " with graphviz.\n"; 3253 if (std::error_code EC = sys::fs::remove(Filename)) { 3254 BC.errs() << "BOLT-WARNING: " << EC.message() << ", failed to remove " 3255 << Filename << "\n"; 3256 } 3257 } 3258 3259 void BinaryFunction::dumpGraphForPass(std::string Annotation) const { 3260 if (!opts::shouldPrint(*this)) 3261 return; 3262 3263 std::string Filename = constructFilename(getPrintName(), Annotation, ".dot"); 3264 if (opts::Verbosity >= 1) 3265 BC.outs() << "BOLT-INFO: dumping CFG to " << Filename << "\n"; 3266 dumpGraphToFile(Filename); 3267 } 3268 3269 void BinaryFunction::dumpGraphToFile(std::string Filename) const { 3270 std::error_code EC; 3271 raw_fd_ostream of(Filename, EC, sys::fs::OF_None); 3272 if (EC) { 3273 if (opts::Verbosity >= 1) { 3274 BC.errs() << "BOLT-WARNING: " << EC.message() << ", unable to open " 3275 << Filename << " for output.\n"; 3276 } 3277 return; 3278 } 3279 dumpGraph(of); 3280 } 3281 3282 bool BinaryFunction::validateCFG() const { 3283 // Skip the validation of CFG after it is finalized 3284 if (CurrentState == State::CFG_Finalized) 3285 return true; 3286 3287 for (BinaryBasicBlock *BB : BasicBlocks) 3288 if (!BB->validateSuccessorInvariants()) 3289 return false; 3290 3291 // Make sure all blocks in CFG are valid. 3292 auto validateBlock = [this](const BinaryBasicBlock *BB, StringRef Desc) { 3293 if (!BB->isValid()) { 3294 BC.errs() << "BOLT-ERROR: deleted " << Desc << " " << BB->getName() 3295 << " detected in:\n"; 3296 this->dump(); 3297 return false; 3298 } 3299 return true; 3300 }; 3301 for (const BinaryBasicBlock *BB : BasicBlocks) { 3302 if (!validateBlock(BB, "block")) 3303 return false; 3304 for (const BinaryBasicBlock *PredBB : BB->predecessors()) 3305 if (!validateBlock(PredBB, "predecessor")) 3306 return false; 3307 for (const BinaryBasicBlock *SuccBB : BB->successors()) 3308 if (!validateBlock(SuccBB, "successor")) 3309 return false; 3310 for (const BinaryBasicBlock *LP : BB->landing_pads()) 3311 if (!validateBlock(LP, "landing pad")) 3312 return false; 3313 for (const BinaryBasicBlock *Thrower : BB->throwers()) 3314 if (!validateBlock(Thrower, "thrower")) 3315 return false; 3316 } 3317 3318 for (const BinaryBasicBlock *BB : BasicBlocks) { 3319 std::unordered_set<const BinaryBasicBlock *> BBLandingPads; 3320 for (const BinaryBasicBlock *LP : BB->landing_pads()) { 3321 if (BBLandingPads.count(LP)) { 3322 BC.errs() << "BOLT-ERROR: duplicate landing pad detected in" 3323 << BB->getName() << " in function " << *this << '\n'; 3324 return false; 3325 } 3326 BBLandingPads.insert(LP); 3327 } 3328 3329 std::unordered_set<const BinaryBasicBlock *> BBThrowers; 3330 for (const BinaryBasicBlock *Thrower : BB->throwers()) { 3331 if (BBThrowers.count(Thrower)) { 3332 BC.errs() << "BOLT-ERROR: duplicate thrower detected in" 3333 << BB->getName() << " in function " << *this << '\n'; 3334 return false; 3335 } 3336 BBThrowers.insert(Thrower); 3337 } 3338 3339 for (const BinaryBasicBlock *LPBlock : BB->landing_pads()) { 3340 if (!llvm::is_contained(LPBlock->throwers(), BB)) { 3341 BC.errs() << "BOLT-ERROR: inconsistent landing pad detected in " 3342 << *this << ": " << BB->getName() 3343 << " is in LandingPads but not in " << LPBlock->getName() 3344 << " Throwers\n"; 3345 return false; 3346 } 3347 } 3348 for (const BinaryBasicBlock *Thrower : BB->throwers()) { 3349 if (!llvm::is_contained(Thrower->landing_pads(), BB)) { 3350 BC.errs() << "BOLT-ERROR: inconsistent thrower detected in " << *this 3351 << ": " << BB->getName() << " is in Throwers list but not in " 3352 << Thrower->getName() << " LandingPads\n"; 3353 return false; 3354 } 3355 } 3356 } 3357 3358 return true; 3359 } 3360 3361 void BinaryFunction::fixBranches() { 3362 auto &MIB = BC.MIB; 3363 MCContext *Ctx = BC.Ctx.get(); 3364 3365 for (BinaryBasicBlock *BB : BasicBlocks) { 3366 const MCSymbol *TBB = nullptr; 3367 const MCSymbol *FBB = nullptr; 3368 MCInst *CondBranch = nullptr; 3369 MCInst *UncondBranch = nullptr; 3370 if (!BB->analyzeBranch(TBB, FBB, CondBranch, UncondBranch)) 3371 continue; 3372 3373 // We will create unconditional branch with correct destination if needed. 3374 if (UncondBranch) 3375 BB->eraseInstruction(BB->findInstruction(UncondBranch)); 3376 3377 // Basic block that follows the current one in the final layout. 3378 const BinaryBasicBlock *const NextBB = 3379 Layout.getBasicBlockAfter(BB, /*IgnoreSplits=*/false); 3380 3381 if (BB->succ_size() == 1) { 3382 // __builtin_unreachable() could create a conditional branch that 3383 // falls-through into the next function - hence the block will have only 3384 // one valid successor. Since behaviour is undefined - we replace 3385 // the conditional branch with an unconditional if required. 3386 if (CondBranch) 3387 BB->eraseInstruction(BB->findInstruction(CondBranch)); 3388 if (BB->getSuccessor() == NextBB) 3389 continue; 3390 BB->addBranchInstruction(BB->getSuccessor()); 3391 } else if (BB->succ_size() == 2) { 3392 assert(CondBranch && "conditional branch expected"); 3393 const BinaryBasicBlock *TSuccessor = BB->getConditionalSuccessor(true); 3394 const BinaryBasicBlock *FSuccessor = BB->getConditionalSuccessor(false); 3395 3396 // Eliminate unnecessary conditional branch. 3397 if (TSuccessor == FSuccessor) { 3398 // FIXME: at the moment, we cannot safely remove static key branches. 3399 if (MIB->isDynamicBranch(*CondBranch)) { 3400 if (opts::Verbosity) { 3401 BC.outs() 3402 << "BOLT-INFO: unable to remove redundant dynamic branch in " 3403 << *this << '\n'; 3404 } 3405 continue; 3406 } 3407 3408 BB->removeDuplicateConditionalSuccessor(CondBranch); 3409 if (TSuccessor != NextBB) 3410 BB->addBranchInstruction(TSuccessor); 3411 continue; 3412 } 3413 3414 // Reverse branch condition and swap successors. 3415 auto swapSuccessors = [&]() { 3416 if (!MIB->isReversibleBranch(*CondBranch)) { 3417 if (opts::Verbosity) { 3418 BC.outs() << "BOLT-INFO: unable to swap successors in " << *this 3419 << '\n'; 3420 } 3421 return false; 3422 } 3423 std::swap(TSuccessor, FSuccessor); 3424 BB->swapConditionalSuccessors(); 3425 auto L = BC.scopeLock(); 3426 MIB->reverseBranchCondition(*CondBranch, TSuccessor->getLabel(), Ctx); 3427 return true; 3428 }; 3429 3430 // Check whether the next block is a "taken" target and try to swap it 3431 // with a "fall-through" target. 3432 if (TSuccessor == NextBB && swapSuccessors()) 3433 continue; 3434 3435 // Update conditional branch destination if needed. 3436 if (MIB->getTargetSymbol(*CondBranch) != TSuccessor->getLabel()) { 3437 auto L = BC.scopeLock(); 3438 MIB->replaceBranchTarget(*CondBranch, TSuccessor->getLabel(), Ctx); 3439 } 3440 3441 // No need for the unconditional branch. 3442 if (FSuccessor == NextBB) 3443 continue; 3444 3445 if (BC.isX86()) { 3446 // We are going to generate two branches. Check if their targets are in 3447 // the same fragment as this block. If only one target is in the same 3448 // fragment, make it the destination of the conditional branch. There 3449 // is a chance it will be a short branch which takes 4 bytes fewer than 3450 // a long conditional branch. For unconditional branch, the difference 3451 // is 3 bytes. 3452 if (BB->getFragmentNum() != TSuccessor->getFragmentNum() && 3453 BB->getFragmentNum() == FSuccessor->getFragmentNum()) 3454 swapSuccessors(); 3455 } 3456 3457 BB->addBranchInstruction(FSuccessor); 3458 } 3459 // Cases where the number of successors is 0 (block ends with a 3460 // terminator) or more than 2 (switch table) don't require branch 3461 // instruction adjustments. 3462 } 3463 assert((!isSimple() || validateCFG()) && 3464 "Invalid CFG detected after fixing branches"); 3465 } 3466 3467 void BinaryFunction::propagateGnuArgsSizeInfo( 3468 MCPlusBuilder::AllocatorIdTy AllocId) { 3469 assert(CurrentState == State::Disassembled && "unexpected function state"); 3470 3471 if (!hasEHRanges() || !usesGnuArgsSize()) 3472 return; 3473 3474 // The current value of DW_CFA_GNU_args_size affects all following 3475 // invoke instructions until the next CFI overrides it. 3476 // It is important to iterate basic blocks in the original order when 3477 // assigning the value. 3478 uint64_t CurrentGnuArgsSize = 0; 3479 for (BinaryBasicBlock *BB : BasicBlocks) { 3480 for (auto II = BB->begin(); II != BB->end();) { 3481 MCInst &Instr = *II; 3482 if (BC.MIB->isCFI(Instr)) { 3483 const MCCFIInstruction *CFI = getCFIFor(Instr); 3484 if (CFI->getOperation() == MCCFIInstruction::OpGnuArgsSize) { 3485 CurrentGnuArgsSize = CFI->getOffset(); 3486 // Delete DW_CFA_GNU_args_size instructions and only regenerate 3487 // during the final code emission. The information is embedded 3488 // inside call instructions. 3489 II = BB->erasePseudoInstruction(II); 3490 continue; 3491 } 3492 } else if (BC.MIB->isInvoke(Instr)) { 3493 // Add the value of GNU_args_size as an extra operand to invokes. 3494 BC.MIB->addGnuArgsSize(Instr, CurrentGnuArgsSize); 3495 } 3496 ++II; 3497 } 3498 } 3499 } 3500 3501 void BinaryFunction::postProcessBranches() { 3502 if (!isSimple()) 3503 return; 3504 for (BinaryBasicBlock &BB : blocks()) { 3505 auto LastInstrRI = BB.getLastNonPseudo(); 3506 if (BB.succ_size() == 1) { 3507 if (LastInstrRI != BB.rend() && 3508 BC.MIB->isConditionalBranch(*LastInstrRI)) { 3509 // __builtin_unreachable() could create a conditional branch that 3510 // falls-through into the next function - hence the block will have only 3511 // one valid successor. Such behaviour is undefined and thus we remove 3512 // the conditional branch while leaving a valid successor. 3513 BB.eraseInstruction(std::prev(LastInstrRI.base())); 3514 LLVM_DEBUG(dbgs() << "BOLT-DEBUG: erasing conditional branch in " 3515 << BB.getName() << " in function " << *this << '\n'); 3516 } 3517 } else if (BB.succ_size() == 0) { 3518 // Ignore unreachable basic blocks. 3519 if (BB.pred_size() == 0 || BB.isLandingPad()) 3520 continue; 3521 3522 // If it's the basic block that does not end up with a terminator - we 3523 // insert a return instruction unless it's a call instruction. 3524 if (LastInstrRI == BB.rend()) { 3525 LLVM_DEBUG( 3526 dbgs() << "BOLT-DEBUG: at least one instruction expected in BB " 3527 << BB.getName() << " in function " << *this << '\n'); 3528 continue; 3529 } 3530 if (!BC.MIB->isTerminator(*LastInstrRI) && 3531 !BC.MIB->isCall(*LastInstrRI)) { 3532 LLVM_DEBUG(dbgs() << "BOLT-DEBUG: adding return to basic block " 3533 << BB.getName() << " in function " << *this << '\n'); 3534 MCInst ReturnInstr; 3535 BC.MIB->createReturn(ReturnInstr); 3536 BB.addInstruction(ReturnInstr); 3537 } 3538 } 3539 } 3540 assert(validateCFG() && "invalid CFG"); 3541 } 3542 3543 MCSymbol *BinaryFunction::addEntryPointAtOffset(uint64_t Offset) { 3544 assert(Offset && "cannot add primary entry point"); 3545 assert(CurrentState == State::Empty || CurrentState == State::Disassembled); 3546 3547 const uint64_t EntryPointAddress = getAddress() + Offset; 3548 MCSymbol *LocalSymbol = getOrCreateLocalLabel(EntryPointAddress); 3549 3550 MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(LocalSymbol); 3551 if (EntrySymbol) 3552 return EntrySymbol; 3553 3554 if (BinaryData *EntryBD = BC.getBinaryDataAtAddress(EntryPointAddress)) { 3555 EntrySymbol = EntryBD->getSymbol(); 3556 } else { 3557 EntrySymbol = BC.getOrCreateGlobalSymbol( 3558 EntryPointAddress, Twine("__ENTRY_") + getOneName() + "@"); 3559 } 3560 SecondaryEntryPoints[LocalSymbol] = EntrySymbol; 3561 3562 BC.setSymbolToFunctionMap(EntrySymbol, this); 3563 3564 return EntrySymbol; 3565 } 3566 3567 MCSymbol *BinaryFunction::addEntryPoint(const BinaryBasicBlock &BB) { 3568 assert(CurrentState == State::CFG && 3569 "basic block can be added as an entry only in a function with CFG"); 3570 3571 if (&BB == BasicBlocks.front()) 3572 return getSymbol(); 3573 3574 MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(BB); 3575 if (EntrySymbol) 3576 return EntrySymbol; 3577 3578 EntrySymbol = 3579 BC.Ctx->getOrCreateSymbol("__ENTRY_" + BB.getLabel()->getName()); 3580 3581 SecondaryEntryPoints[BB.getLabel()] = EntrySymbol; 3582 3583 BC.setSymbolToFunctionMap(EntrySymbol, this); 3584 3585 return EntrySymbol; 3586 } 3587 3588 MCSymbol *BinaryFunction::getSymbolForEntryID(uint64_t EntryID) { 3589 if (EntryID == 0) 3590 return getSymbol(); 3591 3592 if (!isMultiEntry()) 3593 return nullptr; 3594 3595 uint64_t NumEntries = 1; 3596 if (hasCFG()) { 3597 for (BinaryBasicBlock *BB : BasicBlocks) { 3598 MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(*BB); 3599 if (!EntrySymbol) 3600 continue; 3601 if (NumEntries == EntryID) 3602 return EntrySymbol; 3603 ++NumEntries; 3604 } 3605 } else { 3606 for (std::pair<const uint32_t, MCSymbol *> &KV : Labels) { 3607 MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(KV.second); 3608 if (!EntrySymbol) 3609 continue; 3610 if (NumEntries == EntryID) 3611 return EntrySymbol; 3612 ++NumEntries; 3613 } 3614 } 3615 3616 return nullptr; 3617 } 3618 3619 uint64_t BinaryFunction::getEntryIDForSymbol(const MCSymbol *Symbol) const { 3620 if (!isMultiEntry()) 3621 return 0; 3622 3623 for (const MCSymbol *FunctionSymbol : getSymbols()) 3624 if (FunctionSymbol == Symbol) 3625 return 0; 3626 3627 // Check all secondary entries available as either basic blocks or lables. 3628 uint64_t NumEntries = 1; 3629 for (const BinaryBasicBlock *BB : BasicBlocks) { 3630 MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(*BB); 3631 if (!EntrySymbol) 3632 continue; 3633 if (EntrySymbol == Symbol) 3634 return NumEntries; 3635 ++NumEntries; 3636 } 3637 NumEntries = 1; 3638 for (const std::pair<const uint32_t, MCSymbol *> &KV : Labels) { 3639 MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(KV.second); 3640 if (!EntrySymbol) 3641 continue; 3642 if (EntrySymbol == Symbol) 3643 return NumEntries; 3644 ++NumEntries; 3645 } 3646 3647 llvm_unreachable("symbol not found"); 3648 } 3649 3650 bool BinaryFunction::forEachEntryPoint(EntryPointCallbackTy Callback) const { 3651 bool Status = Callback(0, getSymbol()); 3652 if (!isMultiEntry()) 3653 return Status; 3654 3655 for (const std::pair<const uint32_t, MCSymbol *> &KV : Labels) { 3656 if (!Status) 3657 break; 3658 3659 MCSymbol *EntrySymbol = getSecondaryEntryPointSymbol(KV.second); 3660 if (!EntrySymbol) 3661 continue; 3662 3663 Status = Callback(KV.first, EntrySymbol); 3664 } 3665 3666 return Status; 3667 } 3668 3669 BinaryFunction::BasicBlockListType BinaryFunction::dfs() const { 3670 BasicBlockListType DFS; 3671 std::stack<BinaryBasicBlock *> Stack; 3672 std::set<BinaryBasicBlock *> Visited; 3673 3674 // Push entry points to the stack in reverse order. 3675 // 3676 // NB: we rely on the original order of entries to match. 3677 SmallVector<BinaryBasicBlock *> EntryPoints; 3678 llvm::copy_if(BasicBlocks, std::back_inserter(EntryPoints), 3679 [&](const BinaryBasicBlock *const BB) { return isEntryPoint(*BB); }); 3680 // Sort entry points by their offset to make sure we got them in the right 3681 // order. 3682 llvm::stable_sort(EntryPoints, [](const BinaryBasicBlock *const A, 3683 const BinaryBasicBlock *const B) { 3684 return A->getOffset() < B->getOffset(); 3685 }); 3686 for (BinaryBasicBlock *const BB : reverse(EntryPoints)) 3687 Stack.push(BB); 3688 3689 while (!Stack.empty()) { 3690 BinaryBasicBlock *BB = Stack.top(); 3691 Stack.pop(); 3692 3693 if (Visited.find(BB) != Visited.end()) 3694 continue; 3695 Visited.insert(BB); 3696 DFS.push_back(BB); 3697 3698 for (BinaryBasicBlock *SuccBB : BB->landing_pads()) { 3699 Stack.push(SuccBB); 3700 } 3701 3702 const MCSymbol *TBB = nullptr; 3703 const MCSymbol *FBB = nullptr; 3704 MCInst *CondBranch = nullptr; 3705 MCInst *UncondBranch = nullptr; 3706 if (BB->analyzeBranch(TBB, FBB, CondBranch, UncondBranch) && CondBranch && 3707 BB->succ_size() == 2) { 3708 if (BC.MIB->getCanonicalBranchCondCode(BC.MIB->getCondCode( 3709 *CondBranch)) == BC.MIB->getCondCode(*CondBranch)) { 3710 Stack.push(BB->getConditionalSuccessor(true)); 3711 Stack.push(BB->getConditionalSuccessor(false)); 3712 } else { 3713 Stack.push(BB->getConditionalSuccessor(false)); 3714 Stack.push(BB->getConditionalSuccessor(true)); 3715 } 3716 } else { 3717 for (BinaryBasicBlock *SuccBB : BB->successors()) { 3718 Stack.push(SuccBB); 3719 } 3720 } 3721 } 3722 3723 return DFS; 3724 } 3725 3726 size_t BinaryFunction::computeHash(bool UseDFS, HashFunction HashFunction, 3727 OperandHashFuncTy OperandHashFunc) const { 3728 LLVM_DEBUG({ 3729 dbgs() << "BOLT-DEBUG: computeHash " << getPrintName() << ' ' 3730 << (UseDFS ? "dfs" : "bin") << " order " 3731 << (HashFunction == HashFunction::StdHash ? "std::hash" : "xxh3") 3732 << '\n'; 3733 }); 3734 3735 if (size() == 0) 3736 return 0; 3737 3738 assert(hasCFG() && "function is expected to have CFG"); 3739 3740 SmallVector<const BinaryBasicBlock *, 0> Order; 3741 if (UseDFS) 3742 llvm::copy(dfs(), std::back_inserter(Order)); 3743 else 3744 llvm::copy(Layout.blocks(), std::back_inserter(Order)); 3745 3746 // The hash is computed by creating a string of all instruction opcodes and 3747 // possibly their operands and then hashing that string with std::hash. 3748 std::string HashString; 3749 for (const BinaryBasicBlock *BB : Order) 3750 HashString.append(hashBlock(BC, *BB, OperandHashFunc)); 3751 3752 switch (HashFunction) { 3753 case HashFunction::StdHash: 3754 return Hash = std::hash<std::string>{}(HashString); 3755 case HashFunction::XXH3: 3756 return Hash = llvm::xxh3_64bits(HashString); 3757 } 3758 llvm_unreachable("Unhandled HashFunction"); 3759 } 3760 3761 void BinaryFunction::insertBasicBlocks( 3762 BinaryBasicBlock *Start, 3763 std::vector<std::unique_ptr<BinaryBasicBlock>> &&NewBBs, 3764 const bool UpdateLayout, const bool UpdateCFIState, 3765 const bool RecomputeLandingPads) { 3766 const int64_t StartIndex = Start ? getIndex(Start) : -1LL; 3767 const size_t NumNewBlocks = NewBBs.size(); 3768 3769 BasicBlocks.insert(BasicBlocks.begin() + (StartIndex + 1), NumNewBlocks, 3770 nullptr); 3771 3772 int64_t I = StartIndex + 1; 3773 for (std::unique_ptr<BinaryBasicBlock> &BB : NewBBs) { 3774 assert(!BasicBlocks[I]); 3775 BasicBlocks[I++] = BB.release(); 3776 } 3777 3778 if (RecomputeLandingPads) 3779 recomputeLandingPads(); 3780 else 3781 updateBBIndices(0); 3782 3783 if (UpdateLayout) 3784 updateLayout(Start, NumNewBlocks); 3785 3786 if (UpdateCFIState) 3787 updateCFIState(Start, NumNewBlocks); 3788 } 3789 3790 BinaryFunction::iterator BinaryFunction::insertBasicBlocks( 3791 BinaryFunction::iterator StartBB, 3792 std::vector<std::unique_ptr<BinaryBasicBlock>> &&NewBBs, 3793 const bool UpdateLayout, const bool UpdateCFIState, 3794 const bool RecomputeLandingPads) { 3795 const unsigned StartIndex = getIndex(&*StartBB); 3796 const size_t NumNewBlocks = NewBBs.size(); 3797 3798 BasicBlocks.insert(BasicBlocks.begin() + StartIndex + 1, NumNewBlocks, 3799 nullptr); 3800 auto RetIter = BasicBlocks.begin() + StartIndex + 1; 3801 3802 unsigned I = StartIndex + 1; 3803 for (std::unique_ptr<BinaryBasicBlock> &BB : NewBBs) { 3804 assert(!BasicBlocks[I]); 3805 BasicBlocks[I++] = BB.release(); 3806 } 3807 3808 if (RecomputeLandingPads) 3809 recomputeLandingPads(); 3810 else 3811 updateBBIndices(0); 3812 3813 if (UpdateLayout) 3814 updateLayout(*std::prev(RetIter), NumNewBlocks); 3815 3816 if (UpdateCFIState) 3817 updateCFIState(*std::prev(RetIter), NumNewBlocks); 3818 3819 return RetIter; 3820 } 3821 3822 void BinaryFunction::updateBBIndices(const unsigned StartIndex) { 3823 for (unsigned I = StartIndex; I < BasicBlocks.size(); ++I) 3824 BasicBlocks[I]->Index = I; 3825 } 3826 3827 void BinaryFunction::updateCFIState(BinaryBasicBlock *Start, 3828 const unsigned NumNewBlocks) { 3829 const int32_t CFIState = Start->getCFIStateAtExit(); 3830 const unsigned StartIndex = getIndex(Start) + 1; 3831 for (unsigned I = 0; I < NumNewBlocks; ++I) 3832 BasicBlocks[StartIndex + I]->setCFIState(CFIState); 3833 } 3834 3835 void BinaryFunction::updateLayout(BinaryBasicBlock *Start, 3836 const unsigned NumNewBlocks) { 3837 BasicBlockListType::iterator Begin; 3838 BasicBlockListType::iterator End; 3839 3840 // If start not provided copy new blocks from the beginning of BasicBlocks 3841 if (!Start) { 3842 Begin = BasicBlocks.begin(); 3843 End = BasicBlocks.begin() + NumNewBlocks; 3844 } else { 3845 unsigned StartIndex = getIndex(Start); 3846 Begin = std::next(BasicBlocks.begin(), StartIndex + 1); 3847 End = std::next(BasicBlocks.begin(), StartIndex + NumNewBlocks + 1); 3848 } 3849 3850 // Insert new blocks in the layout immediately after Start. 3851 Layout.insertBasicBlocks(Start, {Begin, End}); 3852 Layout.updateLayoutIndices(); 3853 } 3854 3855 bool BinaryFunction::checkForAmbiguousJumpTables() { 3856 SmallSet<uint64_t, 4> JumpTables; 3857 for (BinaryBasicBlock *&BB : BasicBlocks) { 3858 for (MCInst &Inst : *BB) { 3859 if (!BC.MIB->isIndirectBranch(Inst)) 3860 continue; 3861 uint64_t JTAddress = BC.MIB->getJumpTable(Inst); 3862 if (!JTAddress) 3863 continue; 3864 // This address can be inside another jump table, but we only consider 3865 // it ambiguous when the same start address is used, not the same JT 3866 // object. 3867 if (!JumpTables.count(JTAddress)) { 3868 JumpTables.insert(JTAddress); 3869 continue; 3870 } 3871 return true; 3872 } 3873 } 3874 return false; 3875 } 3876 3877 void BinaryFunction::disambiguateJumpTables( 3878 MCPlusBuilder::AllocatorIdTy AllocId) { 3879 assert((opts::JumpTables != JTS_BASIC && isSimple()) || !BC.HasRelocations); 3880 SmallPtrSet<JumpTable *, 4> JumpTables; 3881 for (BinaryBasicBlock *&BB : BasicBlocks) { 3882 for (MCInst &Inst : *BB) { 3883 if (!BC.MIB->isIndirectBranch(Inst)) 3884 continue; 3885 JumpTable *JT = getJumpTable(Inst); 3886 if (!JT) 3887 continue; 3888 auto Iter = JumpTables.find(JT); 3889 if (Iter == JumpTables.end()) { 3890 JumpTables.insert(JT); 3891 continue; 3892 } 3893 // This instruction is an indirect jump using a jump table, but it is 3894 // using the same jump table of another jump. Try all our tricks to 3895 // extract the jump table symbol and make it point to a new, duplicated JT 3896 MCPhysReg BaseReg1; 3897 uint64_t Scale; 3898 const MCSymbol *Target; 3899 // In case we match if our first matcher, first instruction is the one to 3900 // patch 3901 MCInst *JTLoadInst = &Inst; 3902 // Try a standard indirect jump matcher, scale 8 3903 std::unique_ptr<MCPlusBuilder::MCInstMatcher> IndJmpMatcher = 3904 BC.MIB->matchIndJmp(BC.MIB->matchReg(BaseReg1), 3905 BC.MIB->matchImm(Scale), BC.MIB->matchReg(), 3906 /*Offset=*/BC.MIB->matchSymbol(Target)); 3907 if (!IndJmpMatcher->match( 3908 *BC.MRI, *BC.MIB, 3909 MutableArrayRef<MCInst>(&*BB->begin(), &Inst + 1), -1) || 3910 BaseReg1 != BC.MIB->getNoRegister() || Scale != 8) { 3911 MCPhysReg BaseReg2; 3912 uint64_t Offset; 3913 // Standard JT matching failed. Trying now: 3914 // movq "jt.2397/1"(,%rax,8), %rax 3915 // jmpq *%rax 3916 std::unique_ptr<MCPlusBuilder::MCInstMatcher> LoadMatcherOwner = 3917 BC.MIB->matchLoad(BC.MIB->matchReg(BaseReg1), 3918 BC.MIB->matchImm(Scale), BC.MIB->matchReg(), 3919 /*Offset=*/BC.MIB->matchSymbol(Target)); 3920 MCPlusBuilder::MCInstMatcher *LoadMatcher = LoadMatcherOwner.get(); 3921 std::unique_ptr<MCPlusBuilder::MCInstMatcher> IndJmpMatcher2 = 3922 BC.MIB->matchIndJmp(std::move(LoadMatcherOwner)); 3923 if (!IndJmpMatcher2->match( 3924 *BC.MRI, *BC.MIB, 3925 MutableArrayRef<MCInst>(&*BB->begin(), &Inst + 1), -1) || 3926 BaseReg1 != BC.MIB->getNoRegister() || Scale != 8) { 3927 // JT matching failed. Trying now: 3928 // PIC-style matcher, scale 4 3929 // addq %rdx, %rsi 3930 // addq %rdx, %rdi 3931 // leaq DATAat0x402450(%rip), %r11 3932 // movslq (%r11,%rdx,4), %rcx 3933 // addq %r11, %rcx 3934 // jmpq *%rcx # JUMPTABLE @0x402450 3935 std::unique_ptr<MCPlusBuilder::MCInstMatcher> PICIndJmpMatcher = 3936 BC.MIB->matchIndJmp(BC.MIB->matchAdd( 3937 BC.MIB->matchReg(BaseReg1), 3938 BC.MIB->matchLoad(BC.MIB->matchReg(BaseReg2), 3939 BC.MIB->matchImm(Scale), BC.MIB->matchReg(), 3940 BC.MIB->matchImm(Offset)))); 3941 std::unique_ptr<MCPlusBuilder::MCInstMatcher> LEAMatcherOwner = 3942 BC.MIB->matchLoadAddr(BC.MIB->matchSymbol(Target)); 3943 MCPlusBuilder::MCInstMatcher *LEAMatcher = LEAMatcherOwner.get(); 3944 std::unique_ptr<MCPlusBuilder::MCInstMatcher> PICBaseAddrMatcher = 3945 BC.MIB->matchIndJmp(BC.MIB->matchAdd(std::move(LEAMatcherOwner), 3946 BC.MIB->matchAnyOperand())); 3947 if (!PICIndJmpMatcher->match( 3948 *BC.MRI, *BC.MIB, 3949 MutableArrayRef<MCInst>(&*BB->begin(), &Inst + 1), -1) || 3950 Scale != 4 || BaseReg1 != BaseReg2 || Offset != 0 || 3951 !PICBaseAddrMatcher->match( 3952 *BC.MRI, *BC.MIB, 3953 MutableArrayRef<MCInst>(&*BB->begin(), &Inst + 1), -1)) { 3954 llvm_unreachable("Failed to extract jump table base"); 3955 continue; 3956 } 3957 // Matched PIC, identify the instruction with the reference to the JT 3958 JTLoadInst = LEAMatcher->CurInst; 3959 } else { 3960 // Matched non-PIC 3961 JTLoadInst = LoadMatcher->CurInst; 3962 } 3963 } 3964 3965 uint64_t NewJumpTableID = 0; 3966 const MCSymbol *NewJTLabel; 3967 std::tie(NewJumpTableID, NewJTLabel) = 3968 BC.duplicateJumpTable(*this, JT, Target); 3969 { 3970 auto L = BC.scopeLock(); 3971 BC.MIB->replaceMemOperandDisp(*JTLoadInst, NewJTLabel, BC.Ctx.get()); 3972 } 3973 // We use a unique ID with the high bit set as address for this "injected" 3974 // jump table (not originally in the input binary). 3975 BC.MIB->setJumpTable(Inst, NewJumpTableID, 0, AllocId); 3976 } 3977 } 3978 } 3979 3980 bool BinaryFunction::replaceJumpTableEntryIn(BinaryBasicBlock *BB, 3981 BinaryBasicBlock *OldDest, 3982 BinaryBasicBlock *NewDest) { 3983 MCInst *Instr = BB->getLastNonPseudoInstr(); 3984 if (!Instr || !BC.MIB->isIndirectBranch(*Instr)) 3985 return false; 3986 uint64_t JTAddress = BC.MIB->getJumpTable(*Instr); 3987 assert(JTAddress && "Invalid jump table address"); 3988 JumpTable *JT = getJumpTableContainingAddress(JTAddress); 3989 assert(JT && "No jump table structure for this indirect branch"); 3990 bool Patched = JT->replaceDestination(JTAddress, OldDest->getLabel(), 3991 NewDest->getLabel()); 3992 (void)Patched; 3993 assert(Patched && "Invalid entry to be replaced in jump table"); 3994 return true; 3995 } 3996 3997 BinaryBasicBlock *BinaryFunction::splitEdge(BinaryBasicBlock *From, 3998 BinaryBasicBlock *To) { 3999 // Create intermediate BB 4000 MCSymbol *Tmp; 4001 { 4002 auto L = BC.scopeLock(); 4003 Tmp = BC.Ctx->createNamedTempSymbol("SplitEdge"); 4004 } 4005 // Link new BBs to the original input offset of the From BB, so we can map 4006 // samples recorded in new BBs back to the original BB seem in the input 4007 // binary (if using BAT) 4008 std::unique_ptr<BinaryBasicBlock> NewBB = createBasicBlock(Tmp); 4009 NewBB->setOffset(From->getInputOffset()); 4010 BinaryBasicBlock *NewBBPtr = NewBB.get(); 4011 4012 // Update "From" BB 4013 auto I = From->succ_begin(); 4014 auto BI = From->branch_info_begin(); 4015 for (; I != From->succ_end(); ++I) { 4016 if (*I == To) 4017 break; 4018 ++BI; 4019 } 4020 assert(I != From->succ_end() && "Invalid CFG edge in splitEdge!"); 4021 uint64_t OrigCount = BI->Count; 4022 uint64_t OrigMispreds = BI->MispredictedCount; 4023 replaceJumpTableEntryIn(From, To, NewBBPtr); 4024 From->replaceSuccessor(To, NewBBPtr, OrigCount, OrigMispreds); 4025 4026 NewBB->addSuccessor(To, OrigCount, OrigMispreds); 4027 NewBB->setExecutionCount(OrigCount); 4028 NewBB->setIsCold(From->isCold()); 4029 4030 // Update CFI and BB layout with new intermediate BB 4031 std::vector<std::unique_ptr<BinaryBasicBlock>> NewBBs; 4032 NewBBs.emplace_back(std::move(NewBB)); 4033 insertBasicBlocks(From, std::move(NewBBs), true, true, 4034 /*RecomputeLandingPads=*/false); 4035 return NewBBPtr; 4036 } 4037 4038 void BinaryFunction::deleteConservativeEdges() { 4039 // Our goal is to aggressively remove edges from the CFG that we believe are 4040 // wrong. This is used for instrumentation, where it is safe to remove 4041 // fallthrough edges because we won't reorder blocks. 4042 for (auto I = BasicBlocks.begin(), E = BasicBlocks.end(); I != E; ++I) { 4043 BinaryBasicBlock *BB = *I; 4044 if (BB->succ_size() != 1 || BB->size() == 0) 4045 continue; 4046 4047 auto NextBB = std::next(I); 4048 MCInst *Last = BB->getLastNonPseudoInstr(); 4049 // Fallthrough is a landing pad? Delete this edge (as long as we don't 4050 // have a direct jump to it) 4051 if ((*BB->succ_begin())->isLandingPad() && NextBB != E && 4052 *BB->succ_begin() == *NextBB && Last && !BC.MIB->isBranch(*Last)) { 4053 BB->removeAllSuccessors(); 4054 continue; 4055 } 4056 4057 // Look for suspicious calls at the end of BB where gcc may optimize it and 4058 // remove the jump to the epilogue when it knows the call won't return. 4059 if (!Last || !BC.MIB->isCall(*Last)) 4060 continue; 4061 4062 const MCSymbol *CalleeSymbol = BC.MIB->getTargetSymbol(*Last); 4063 if (!CalleeSymbol) 4064 continue; 4065 4066 StringRef CalleeName = CalleeSymbol->getName(); 4067 if (CalleeName != "__cxa_throw@PLT" && CalleeName != "_Unwind_Resume@PLT" && 4068 CalleeName != "__cxa_rethrow@PLT" && CalleeName != "exit@PLT" && 4069 CalleeName != "abort@PLT") 4070 continue; 4071 4072 BB->removeAllSuccessors(); 4073 } 4074 } 4075 4076 bool BinaryFunction::isSymbolValidInScope(const SymbolRef &Symbol, 4077 uint64_t SymbolSize) const { 4078 // If this symbol is in a different section from the one where the 4079 // function symbol is, don't consider it as valid. 4080 if (!getOriginSection()->containsAddress( 4081 cantFail(Symbol.getAddress(), "cannot get symbol address"))) 4082 return false; 4083 4084 // Some symbols are tolerated inside function bodies, others are not. 4085 // The real function boundaries may not be known at this point. 4086 if (BC.isMarker(Symbol)) 4087 return true; 4088 4089 // It's okay to have a zero-sized symbol in the middle of non-zero-sized 4090 // function. 4091 if (SymbolSize == 0 && containsAddress(cantFail(Symbol.getAddress()))) 4092 return true; 4093 4094 if (cantFail(Symbol.getType()) != SymbolRef::ST_Unknown) 4095 return false; 4096 4097 if (cantFail(Symbol.getFlags()) & SymbolRef::SF_Global) 4098 return false; 4099 4100 return true; 4101 } 4102 4103 void BinaryFunction::adjustExecutionCount(uint64_t Count) { 4104 if (getKnownExecutionCount() == 0 || Count == 0) 4105 return; 4106 4107 if (ExecutionCount < Count) 4108 Count = ExecutionCount; 4109 4110 double AdjustmentRatio = ((double)ExecutionCount - Count) / ExecutionCount; 4111 if (AdjustmentRatio < 0.0) 4112 AdjustmentRatio = 0.0; 4113 4114 for (BinaryBasicBlock &BB : blocks()) 4115 BB.adjustExecutionCount(AdjustmentRatio); 4116 4117 ExecutionCount -= Count; 4118 } 4119 4120 BinaryFunction::~BinaryFunction() { 4121 for (BinaryBasicBlock *BB : BasicBlocks) 4122 delete BB; 4123 for (BinaryBasicBlock *BB : DeletedBasicBlocks) 4124 delete BB; 4125 } 4126 4127 void BinaryFunction::constructDomTree() { 4128 BDT.reset(new BinaryDominatorTree); 4129 BDT->recalculate(*this); 4130 } 4131 4132 void BinaryFunction::calculateLoopInfo() { 4133 if (!hasDomTree()) 4134 constructDomTree(); 4135 // Discover loops. 4136 BLI.reset(new BinaryLoopInfo()); 4137 BLI->analyze(getDomTree()); 4138 4139 // Traverse discovered loops and add depth and profile information. 4140 std::stack<BinaryLoop *> St; 4141 for (auto I = BLI->begin(), E = BLI->end(); I != E; ++I) { 4142 St.push(*I); 4143 ++BLI->OuterLoops; 4144 } 4145 4146 while (!St.empty()) { 4147 BinaryLoop *L = St.top(); 4148 St.pop(); 4149 ++BLI->TotalLoops; 4150 BLI->MaximumDepth = std::max(L->getLoopDepth(), BLI->MaximumDepth); 4151 4152 // Add nested loops in the stack. 4153 for (BinaryLoop::iterator I = L->begin(), E = L->end(); I != E; ++I) 4154 St.push(*I); 4155 4156 // Skip if no valid profile is found. 4157 if (!hasValidProfile()) { 4158 L->EntryCount = COUNT_NO_PROFILE; 4159 L->ExitCount = COUNT_NO_PROFILE; 4160 L->TotalBackEdgeCount = COUNT_NO_PROFILE; 4161 continue; 4162 } 4163 4164 // Compute back edge count. 4165 SmallVector<BinaryBasicBlock *, 1> Latches; 4166 L->getLoopLatches(Latches); 4167 4168 for (BinaryBasicBlock *Latch : Latches) { 4169 auto BI = Latch->branch_info_begin(); 4170 for (BinaryBasicBlock *Succ : Latch->successors()) { 4171 if (Succ == L->getHeader()) { 4172 assert(BI->Count != BinaryBasicBlock::COUNT_NO_PROFILE && 4173 "profile data not found"); 4174 L->TotalBackEdgeCount += BI->Count; 4175 } 4176 ++BI; 4177 } 4178 } 4179 4180 // Compute entry count. 4181 L->EntryCount = L->getHeader()->getExecutionCount() - L->TotalBackEdgeCount; 4182 4183 // Compute exit count. 4184 SmallVector<BinaryLoop::Edge, 1> ExitEdges; 4185 L->getExitEdges(ExitEdges); 4186 for (BinaryLoop::Edge &Exit : ExitEdges) { 4187 const BinaryBasicBlock *Exiting = Exit.first; 4188 const BinaryBasicBlock *ExitTarget = Exit.second; 4189 auto BI = Exiting->branch_info_begin(); 4190 for (BinaryBasicBlock *Succ : Exiting->successors()) { 4191 if (Succ == ExitTarget) { 4192 assert(BI->Count != BinaryBasicBlock::COUNT_NO_PROFILE && 4193 "profile data not found"); 4194 L->ExitCount += BI->Count; 4195 } 4196 ++BI; 4197 } 4198 } 4199 } 4200 } 4201 4202 void BinaryFunction::updateOutputValues(const BOLTLinker &Linker) { 4203 if (!isEmitted()) { 4204 assert(!isInjected() && "injected function should be emitted"); 4205 setOutputAddress(getAddress()); 4206 setOutputSize(getSize()); 4207 return; 4208 } 4209 4210 const auto SymbolInfo = Linker.lookupSymbolInfo(getSymbol()->getName()); 4211 assert(SymbolInfo && "Cannot find function entry symbol"); 4212 setOutputAddress(SymbolInfo->Address); 4213 setOutputSize(SymbolInfo->Size); 4214 4215 if (BC.HasRelocations || isInjected()) { 4216 if (hasConstantIsland()) { 4217 const auto DataAddress = 4218 Linker.lookupSymbol(getFunctionConstantIslandLabel()->getName()); 4219 assert(DataAddress && "Cannot find function CI symbol"); 4220 setOutputDataAddress(*DataAddress); 4221 for (auto It : Islands->Offsets) { 4222 const uint64_t OldOffset = It.first; 4223 BinaryData *BD = BC.getBinaryDataAtAddress(getAddress() + OldOffset); 4224 if (!BD) 4225 continue; 4226 4227 MCSymbol *Symbol = It.second; 4228 const auto NewAddress = Linker.lookupSymbol(Symbol->getName()); 4229 assert(NewAddress && "Cannot find CI symbol"); 4230 auto &Section = *getCodeSection(); 4231 const auto NewOffset = *NewAddress - Section.getOutputAddress(); 4232 BD->setOutputLocation(Section, NewOffset); 4233 } 4234 } 4235 if (isSplit()) { 4236 for (FunctionFragment &FF : getLayout().getSplitFragments()) { 4237 ErrorOr<BinarySection &> ColdSection = 4238 getCodeSection(FF.getFragmentNum()); 4239 // If fragment is empty, cold section might not exist 4240 if (FF.empty() && ColdSection.getError()) 4241 continue; 4242 4243 const MCSymbol *ColdStartSymbol = getSymbol(FF.getFragmentNum()); 4244 // If fragment is empty, symbol might have not been emitted 4245 if (FF.empty() && (!ColdStartSymbol || !ColdStartSymbol->isDefined()) && 4246 !hasConstantIsland()) 4247 continue; 4248 assert(ColdStartSymbol && ColdStartSymbol->isDefined() && 4249 "split function should have defined cold symbol"); 4250 const auto ColdStartSymbolInfo = 4251 Linker.lookupSymbolInfo(ColdStartSymbol->getName()); 4252 assert(ColdStartSymbolInfo && "Cannot find cold start symbol"); 4253 FF.setAddress(ColdStartSymbolInfo->Address); 4254 FF.setImageSize(ColdStartSymbolInfo->Size); 4255 if (hasConstantIsland()) { 4256 const auto DataAddress = Linker.lookupSymbol( 4257 getFunctionColdConstantIslandLabel()->getName()); 4258 assert(DataAddress && "Cannot find cold CI symbol"); 4259 setOutputColdDataAddress(*DataAddress); 4260 } 4261 } 4262 } 4263 } 4264 4265 // Update basic block output ranges for the debug info, if we have 4266 // secondary entry points in the symbol table to update or if writing BAT. 4267 if (!requiresAddressMap()) 4268 return; 4269 4270 // AArch64 may have functions that only contains a constant island (no code). 4271 if (getLayout().block_empty()) 4272 return; 4273 4274 for (FunctionFragment &FF : getLayout().fragments()) { 4275 if (FF.empty()) 4276 continue; 4277 4278 const uint64_t FragmentBaseAddress = 4279 getCodeSection(isSimple() ? FF.getFragmentNum() : FragmentNum::main()) 4280 ->getOutputAddress(); 4281 4282 BinaryBasicBlock *PrevBB = nullptr; 4283 for (BinaryBasicBlock *const BB : FF) { 4284 assert(BB->getLabel()->isDefined() && "symbol should be defined"); 4285 if (!BC.HasRelocations) { 4286 if (BB->isSplit()) 4287 assert(FragmentBaseAddress == FF.getAddress()); 4288 else 4289 assert(FragmentBaseAddress == getOutputAddress()); 4290 (void)FragmentBaseAddress; 4291 } 4292 4293 // Injected functions likely will fail lookup, as they have no 4294 // input range. Just assign the BB the output address of the 4295 // function. 4296 auto MaybeBBAddress = BC.getIOAddressMap().lookup(BB->getLabel()); 4297 const uint64_t BBAddress = MaybeBBAddress ? *MaybeBBAddress 4298 : BB->isSplit() ? FF.getAddress() 4299 : getOutputAddress(); 4300 BB->setOutputStartAddress(BBAddress); 4301 4302 if (PrevBB) { 4303 assert(PrevBB->getOutputAddressRange().first <= BBAddress && 4304 "Bad output address for basic block."); 4305 assert((PrevBB->getOutputAddressRange().first != BBAddress || 4306 !hasInstructions() || !PrevBB->getNumNonPseudos()) && 4307 "Bad output address for basic block."); 4308 PrevBB->setOutputEndAddress(BBAddress); 4309 } 4310 PrevBB = BB; 4311 } 4312 4313 PrevBB->setOutputEndAddress(PrevBB->isSplit() 4314 ? FF.getAddress() + FF.getImageSize() 4315 : getOutputAddress() + getOutputSize()); 4316 } 4317 4318 // Reset output addresses for deleted blocks. 4319 for (BinaryBasicBlock *BB : DeletedBasicBlocks) { 4320 BB->setOutputStartAddress(0); 4321 BB->setOutputEndAddress(0); 4322 } 4323 } 4324 4325 DebugAddressRangesVector BinaryFunction::getOutputAddressRanges() const { 4326 DebugAddressRangesVector OutputRanges; 4327 4328 if (isFolded()) 4329 return OutputRanges; 4330 4331 if (IsFragment) 4332 return OutputRanges; 4333 4334 OutputRanges.emplace_back(getOutputAddress(), 4335 getOutputAddress() + getOutputSize()); 4336 if (isSplit()) { 4337 assert(isEmitted() && "split function should be emitted"); 4338 for (const FunctionFragment &FF : getLayout().getSplitFragments()) 4339 OutputRanges.emplace_back(FF.getAddress(), 4340 FF.getAddress() + FF.getImageSize()); 4341 } 4342 4343 if (isSimple()) 4344 return OutputRanges; 4345 4346 for (BinaryFunction *Frag : Fragments) { 4347 assert(!Frag->isSimple() && 4348 "fragment of non-simple function should also be non-simple"); 4349 OutputRanges.emplace_back(Frag->getOutputAddress(), 4350 Frag->getOutputAddress() + Frag->getOutputSize()); 4351 } 4352 4353 return OutputRanges; 4354 } 4355 4356 uint64_t BinaryFunction::translateInputToOutputAddress(uint64_t Address) const { 4357 if (isFolded()) 4358 return 0; 4359 4360 // If the function hasn't changed return the same address. 4361 if (!isEmitted()) 4362 return Address; 4363 4364 if (Address < getAddress()) 4365 return 0; 4366 4367 // Check if the address is associated with an instruction that is tracked 4368 // by address translation. 4369 if (auto OutputAddress = BC.getIOAddressMap().lookup(Address)) 4370 return *OutputAddress; 4371 4372 // FIXME: #18950828 - we rely on relative offsets inside basic blocks to stay 4373 // intact. Instead we can use pseudo instructions and/or annotations. 4374 const uint64_t Offset = Address - getAddress(); 4375 const BinaryBasicBlock *BB = getBasicBlockContainingOffset(Offset); 4376 if (!BB) { 4377 // Special case for address immediately past the end of the function. 4378 if (Offset == getSize()) 4379 return getOutputAddress() + getOutputSize(); 4380 4381 return 0; 4382 } 4383 4384 return std::min(BB->getOutputAddressRange().first + Offset - BB->getOffset(), 4385 BB->getOutputAddressRange().second); 4386 } 4387 4388 DebugAddressRangesVector 4389 BinaryFunction::translateInputToOutputRange(DebugAddressRange InRange) const { 4390 DebugAddressRangesVector OutRanges; 4391 4392 // The function was removed from the output. Return an empty range. 4393 if (isFolded()) 4394 return OutRanges; 4395 4396 // If the function hasn't changed return the same range. 4397 if (!isEmitted()) { 4398 OutRanges.emplace_back(InRange); 4399 return OutRanges; 4400 } 4401 4402 if (!containsAddress(InRange.LowPC)) 4403 return OutRanges; 4404 4405 // Special case of an empty range [X, X). Some tools expect X to be updated. 4406 if (InRange.LowPC == InRange.HighPC) { 4407 if (uint64_t NewPC = translateInputToOutputAddress(InRange.LowPC)) 4408 OutRanges.push_back(DebugAddressRange{NewPC, NewPC}); 4409 return OutRanges; 4410 } 4411 4412 uint64_t InputOffset = InRange.LowPC - getAddress(); 4413 const uint64_t InputEndOffset = 4414 std::min(InRange.HighPC - getAddress(), getSize()); 4415 4416 auto BBI = llvm::upper_bound(BasicBlockOffsets, 4417 BasicBlockOffset(InputOffset, nullptr), 4418 CompareBasicBlockOffsets()); 4419 assert(BBI != BasicBlockOffsets.begin()); 4420 4421 // Iterate over blocks in the input order using BasicBlockOffsets. 4422 for (--BBI; InputOffset < InputEndOffset && BBI != BasicBlockOffsets.end(); 4423 InputOffset = BBI->second->getEndOffset(), ++BBI) { 4424 const BinaryBasicBlock &BB = *BBI->second; 4425 if (InputOffset < BB.getOffset() || InputOffset >= BB.getEndOffset()) { 4426 LLVM_DEBUG( 4427 dbgs() << "BOLT-DEBUG: invalid debug address range detected for " 4428 << *this << " : [0x" << Twine::utohexstr(InRange.LowPC) 4429 << ", 0x" << Twine::utohexstr(InRange.HighPC) << "]\n"); 4430 break; 4431 } 4432 4433 // Skip the block if it wasn't emitted. 4434 if (!BB.getOutputAddressRange().first) 4435 continue; 4436 4437 // Find output address for an instruction with an offset greater or equal 4438 // to /p Offset. The output address should fall within the same basic 4439 // block boundaries. 4440 auto translateBlockOffset = [&](const uint64_t Offset) { 4441 const uint64_t OutAddress = BB.getOutputAddressRange().first + Offset; 4442 return std::min(OutAddress, BB.getOutputAddressRange().second); 4443 }; 4444 4445 uint64_t OutLowPC = BB.getOutputAddressRange().first; 4446 if (InputOffset > BB.getOffset()) 4447 OutLowPC = translateBlockOffset(InputOffset - BB.getOffset()); 4448 4449 uint64_t OutHighPC = BB.getOutputAddressRange().second; 4450 if (InputEndOffset < BB.getEndOffset()) { 4451 assert(InputEndOffset >= BB.getOffset()); 4452 OutHighPC = translateBlockOffset(InputEndOffset - BB.getOffset()); 4453 } 4454 4455 // Check if we can expand the last translated range. 4456 if (!OutRanges.empty() && OutRanges.back().HighPC == OutLowPC) 4457 OutRanges.back().HighPC = std::max(OutRanges.back().HighPC, OutHighPC); 4458 else 4459 OutRanges.emplace_back(OutLowPC, std::max(OutLowPC, OutHighPC)); 4460 } 4461 4462 LLVM_DEBUG({ 4463 dbgs() << "BOLT-DEBUG: translated address range " << InRange << " -> "; 4464 for (const DebugAddressRange &R : OutRanges) 4465 dbgs() << R << ' '; 4466 dbgs() << '\n'; 4467 }); 4468 4469 return OutRanges; 4470 } 4471 4472 MCInst *BinaryFunction::getInstructionAtOffset(uint64_t Offset) { 4473 if (CurrentState == State::Disassembled) { 4474 auto II = Instructions.find(Offset); 4475 return (II == Instructions.end()) ? nullptr : &II->second; 4476 } else if (CurrentState == State::CFG) { 4477 BinaryBasicBlock *BB = getBasicBlockContainingOffset(Offset); 4478 if (!BB) 4479 return nullptr; 4480 4481 for (MCInst &Inst : *BB) { 4482 constexpr uint32_t InvalidOffset = std::numeric_limits<uint32_t>::max(); 4483 if (Offset == BC.MIB->getOffsetWithDefault(Inst, InvalidOffset)) 4484 return &Inst; 4485 } 4486 4487 if (MCInst *LastInstr = BB->getLastNonPseudoInstr()) { 4488 if (std::optional<uint32_t> Size = BC.MIB->getSize(*LastInstr)) { 4489 if (BB->getEndOffset() - Offset == Size) { 4490 return LastInstr; 4491 } 4492 } 4493 } 4494 4495 return nullptr; 4496 } else { 4497 llvm_unreachable("invalid CFG state to use getInstructionAtOffset()"); 4498 } 4499 } 4500 4501 MCInst *BinaryFunction::getInstructionContainingOffset(uint64_t Offset) { 4502 assert(CurrentState == State::Disassembled && "Wrong function state"); 4503 4504 if (Offset > Size) 4505 return nullptr; 4506 4507 auto II = Instructions.upper_bound(Offset); 4508 assert(II != Instructions.begin() && "First instruction not at offset 0"); 4509 --II; 4510 return &II->second; 4511 } 4512 4513 void BinaryFunction::printLoopInfo(raw_ostream &OS) const { 4514 if (!opts::shouldPrint(*this)) 4515 return; 4516 4517 OS << "Loop Info for Function \"" << *this << "\""; 4518 if (hasValidProfile()) 4519 OS << " (count: " << getExecutionCount() << ")"; 4520 OS << "\n"; 4521 4522 std::stack<BinaryLoop *> St; 4523 for (BinaryLoop *L : *BLI) 4524 St.push(L); 4525 while (!St.empty()) { 4526 BinaryLoop *L = St.top(); 4527 St.pop(); 4528 4529 for (BinaryLoop *Inner : *L) 4530 St.push(Inner); 4531 4532 if (!hasValidProfile()) 4533 continue; 4534 4535 OS << (L->getLoopDepth() > 1 ? "Nested" : "Outer") 4536 << " loop header: " << L->getHeader()->getName(); 4537 OS << "\n"; 4538 OS << "Loop basic blocks: "; 4539 ListSeparator LS; 4540 for (BinaryBasicBlock *BB : L->blocks()) 4541 OS << LS << BB->getName(); 4542 OS << "\n"; 4543 if (hasValidProfile()) { 4544 OS << "Total back edge count: " << L->TotalBackEdgeCount << "\n"; 4545 OS << "Loop entry count: " << L->EntryCount << "\n"; 4546 OS << "Loop exit count: " << L->ExitCount << "\n"; 4547 if (L->EntryCount > 0) { 4548 OS << "Average iters per entry: " 4549 << format("%.4lf", (double)L->TotalBackEdgeCount / L->EntryCount) 4550 << "\n"; 4551 } 4552 } 4553 OS << "----\n"; 4554 } 4555 4556 OS << "Total number of loops: " << BLI->TotalLoops << "\n"; 4557 OS << "Number of outer loops: " << BLI->OuterLoops << "\n"; 4558 OS << "Maximum nested loop depth: " << BLI->MaximumDepth << "\n\n"; 4559 } 4560 4561 bool BinaryFunction::isAArch64Veneer() const { 4562 if (empty() || hasIslandsInfo()) 4563 return false; 4564 4565 BinaryBasicBlock &BB = **BasicBlocks.begin(); 4566 for (MCInst &Inst : BB) 4567 if (!BC.MIB->hasAnnotation(Inst, "AArch64Veneer")) 4568 return false; 4569 4570 for (auto I = BasicBlocks.begin() + 1, E = BasicBlocks.end(); I != E; ++I) { 4571 for (MCInst &Inst : **I) 4572 if (!BC.MIB->isNoop(Inst)) 4573 return false; 4574 } 4575 4576 return true; 4577 } 4578 4579 void BinaryFunction::addRelocation(uint64_t Address, MCSymbol *Symbol, 4580 uint64_t RelType, uint64_t Addend, 4581 uint64_t Value) { 4582 assert(Address >= getAddress() && Address < getAddress() + getMaxSize() && 4583 "address is outside of the function"); 4584 uint64_t Offset = Address - getAddress(); 4585 LLVM_DEBUG(dbgs() << "BOLT-DEBUG: addRelocation in " 4586 << formatv("{0}@{1:x} against {2}\n", *this, Offset, 4587 (Symbol ? Symbol->getName() : "<undef>"))); 4588 bool IsCI = BC.isAArch64() && isInConstantIsland(Address); 4589 std::map<uint64_t, Relocation> &Rels = 4590 IsCI ? Islands->Relocations : Relocations; 4591 if (BC.MIB->shouldRecordCodeRelocation(RelType)) 4592 Rels[Offset] = Relocation{Offset, Symbol, RelType, Addend, Value}; 4593 } 4594 4595 } // namespace bolt 4596 } // namespace llvm 4597