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