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