lib/MC/MCDwarf.cpp

   1 //===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "llvm/ADT/FoldingSet.h"
  11 #include "llvm/MC/MCAsmInfo.h"
  12 #include "llvm/MC/MCDwarf.h"
  13 #include "llvm/MC/MCAssembler.h"
  14 #include "llvm/MC/MCStreamer.h"
  15 #include "llvm/MC/MCSymbol.h"
  16 #include "llvm/MC/MCExpr.h"
  17 #include "llvm/MC/MCContext.h"
  18 #include "llvm/MC/MCObjectWriter.h"
  19 #include "llvm/ADT/SmallString.h"
  20 #include "llvm/Support/Debug.h"
  21 #include "llvm/Support/ErrorHandling.h"
  22 #include "llvm/Support/raw_ostream.h"
  23 #include "llvm/Target/TargetAsmBackend.h"
  24 #include "llvm/Target/TargetAsmInfo.h"
  25 using namespace llvm;
  26
  27 // Given a special op, return the address skip amount (in units of
  28 // DWARF2_LINE_MIN_INSN_LENGTH.
  29 #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
  30
  31 // The maximum address skip amount that can be encoded with a special op.
  32 #define MAX_SPECIAL_ADDR_DELTA          SPECIAL_ADDR(255)
  33
  34 // First special line opcode - leave room for the standard opcodes.
  35 // Note: If you want to change this, you'll have to update the
  36 // "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit().
  37 #define DWARF2_LINE_OPCODE_BASE         13
  38
  39 // Minimum line offset in a special line info. opcode.  This value
  40 // was chosen to give a reasonable range of values.
  41 #define DWARF2_LINE_BASE                -5
  42
  43 // Range of line offsets in a special line info. opcode.
  44 # define DWARF2_LINE_RANGE              14
  45
  46 // Define the architecture-dependent minimum instruction length (in bytes).
  47 // This value should be rather too small than too big.
  48 # define DWARF2_LINE_MIN_INSN_LENGTH    1
  49
  50 // Note: when DWARF2_LINE_MIN_INSN_LENGTH == 1 which is the current setting,
  51 // this routine is a nop and will be optimized away.
  52 static inline uint64_t ScaleAddrDelta(uint64_t AddrDelta)
  53 {
  54   if (DWARF2_LINE_MIN_INSN_LENGTH == 1)
  55     return AddrDelta;
  56   if (AddrDelta % DWARF2_LINE_MIN_INSN_LENGTH != 0) {
  57     // TODO: report this error, but really only once.
  58     ;
  59   }
  60   return AddrDelta / DWARF2_LINE_MIN_INSN_LENGTH;
  61 }
  62
  63 //
  64 // This is called when an instruction is assembled into the specified section
  65 // and if there is information from the last .loc directive that has yet to have
  66 // a line entry made for it is made.
  67 //
  68 void MCLineEntry::Make(MCStreamer *MCOS, const MCSection *Section) {
  69   if (!MCOS->getContext().getDwarfLocSeen())
  70     return;
  71
  72   // Create a symbol at in the current section for use in the line entry.
  73   MCSymbol *LineSym = MCOS->getContext().CreateTempSymbol();
  74   // Set the value of the symbol to use for the MCLineEntry.
  75   MCOS->EmitLabel(LineSym);
  76
  77   // Get the current .loc info saved in the context.
  78   const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
  79
  80   // Create a (local) line entry with the symbol and the current .loc info.
  81   MCLineEntry LineEntry(LineSym, DwarfLoc);
  82
  83   // clear DwarfLocSeen saying the current .loc info is now used.
  84   MCOS->getContext().ClearDwarfLocSeen();
  85
  86   // Get the MCLineSection for this section, if one does not exist for this
  87   // section create it.
  88   const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
  89     MCOS->getContext().getMCLineSections();
  90   MCLineSection *LineSection = MCLineSections.lookup(Section);
  91   if (!LineSection) {
  92     // Create a new MCLineSection.  This will be deleted after the dwarf line
  93     // table is created using it by iterating through the MCLineSections
  94     // DenseMap.
  95     LineSection = new MCLineSection;
  96     // Save a pointer to the new LineSection into the MCLineSections DenseMap.
  97     MCOS->getContext().addMCLineSection(Section, LineSection);
  98   }
  99
 100   // Add the line entry to this section's entries.
 101   LineSection->addLineEntry(LineEntry);
 102 }
 103
 104 //
 105 // This helper routine returns an expression of End - Start + IntVal .
 106 //
 107 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
 108                                                   const MCSymbol &Start,
 109                                                   const MCSymbol &End,
 110                                                   int IntVal) {
 111   MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
 112   const MCExpr *Res =
 113     MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext());
 114   const MCExpr *RHS =
 115     MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext());
 116   const MCExpr *Res1 =
 117     MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
 118   const MCExpr *Res2 =
 119     MCConstantExpr::Create(IntVal, MCOS.getContext());
 120   const MCExpr *Res3 =
 121     MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
 122   return Res3;
 123 }
 124
 125 //
 126 // This emits the Dwarf line table for the specified section from the entries
 127 // in the LineSection.
 128 //
 129 static inline void EmitDwarfLineTable(MCStreamer *MCOS,
 130                                       const MCSection *Section,
 131                                       const MCLineSection *LineSection) {
 132   unsigned FileNum = 1;
 133   unsigned LastLine = 1;
 134   unsigned Column = 0;
 135   unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
 136   unsigned Isa = 0;
 137   MCSymbol *LastLabel = NULL;
 138
 139   // Loop through each MCLineEntry and encode the dwarf line number table.
 140   for (MCLineSection::const_iterator
 141          it = LineSection->getMCLineEntries()->begin(),
 142          ie = LineSection->getMCLineEntries()->end(); it != ie; ++it) {
 143
 144     if (FileNum != it->getFileNum()) {
 145       FileNum = it->getFileNum();
 146       MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
 147       MCOS->EmitULEB128IntValue(FileNum);
 148     }
 149     if (Column != it->getColumn()) {
 150       Column = it->getColumn();
 151       MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
 152       MCOS->EmitULEB128IntValue(Column);
 153     }
 154     if (Isa != it->getIsa()) {
 155       Isa = it->getIsa();
 156       MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
 157       MCOS->EmitULEB128IntValue(Isa);
 158     }
 159     if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
 160       Flags = it->getFlags();
 161       MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
 162     }
 163     if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK)
 164       MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
 165     if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END)
 166       MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
 167     if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
 168       MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
 169
 170     int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine;
 171     MCSymbol *Label = it->getLabel();
 172
 173     // At this point we want to emit/create the sequence to encode the delta in
 174     // line numbers and the increment of the address from the previous Label
 175     // and the current Label.
 176     MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label);
 177
 178     LastLine = it->getLine();
 179     LastLabel = Label;
 180   }
 181
 182   // Emit a DW_LNE_end_sequence for the end of the section.
 183   // Using the pointer Section create a temporary label at the end of the
 184   // section and use that and the LastLabel to compute the address delta
 185   // and use INT64_MAX as the line delta which is the signal that this is
 186   // actually a DW_LNE_end_sequence.
 187
 188   // Switch to the section to be able to create a symbol at its end.
 189   MCOS->SwitchSection(Section);
 190
 191   MCContext &context = MCOS->getContext();
 192   // Create a symbol at the end of the section.
 193   MCSymbol *SectionEnd = context.CreateTempSymbol();
 194   // Set the value of the symbol, as we are at the end of the section.
 195   MCOS->EmitLabel(SectionEnd);
 196
 197   // Switch back the the dwarf line section.
 198   MCOS->SwitchSection(context.getTargetAsmInfo().getDwarfLineSection());
 199
 200   MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd);
 201 }
 202
 203 //
 204 // This emits the Dwarf file and the line tables.
 205 //
 206 void MCDwarfFileTable::Emit(MCStreamer *MCOS) {
 207   MCContext &context = MCOS->getContext();
 208   // Switch to the section where the table will be emitted into.
 209   MCOS->SwitchSection(context.getTargetAsmInfo().getDwarfLineSection());
 210
 211   // Create a symbol at the beginning of this section.
 212   MCSymbol *LineStartSym = context.CreateTempSymbol();
 213   // Set the value of the symbol, as we are at the start of the section.
 214   MCOS->EmitLabel(LineStartSym);
 215
 216   // Create a symbol for the end of the section (to be set when we get there).
 217   MCSymbol *LineEndSym = context.CreateTempSymbol();
 218
 219   // The first 4 bytes is the total length of the information for this
 220   // compilation unit (not including these 4 bytes for the length).
 221   MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4),
 222                      4);
 223
 224   // Next 2 bytes is the Version, which is Dwarf 2.
 225   MCOS->EmitIntValue(2, 2);
 226
 227   // Create a symbol for the end of the prologue (to be set when we get there).
 228   MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end
 229
 230   // Length of the prologue, is the next 4 bytes.  Which is the start of the
 231   // section to the end of the prologue.  Not including the 4 bytes for the
 232   // total length, the 2 bytes for the version, and these 4 bytes for the
 233   // length of the prologue.
 234   MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
 235                                         (4 + 2 + 4)),
 236                   4, 0);
 237
 238   // Parameters of the state machine, are next.
 239   MCOS->EmitIntValue(DWARF2_LINE_MIN_INSN_LENGTH, 1);
 240   MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
 241   MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
 242   MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
 243   MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1);
 244
 245   // Standard opcode lengths
 246   MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy
 247   MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc
 248   MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line
 249   MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file
 250   MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column
 251   MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
 252   MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
 253   MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
 254   MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
 255   MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
 256   MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
 257   MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa
 258
 259   // Put out the directory and file tables.
 260
 261   // First the directory table.
 262   const std::vector<StringRef> &MCDwarfDirs =
 263     context.getMCDwarfDirs();
 264   for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
 265     MCOS->EmitBytes(MCDwarfDirs[i], 0); // the DirectoryName
 266     MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
 267   }
 268   MCOS->EmitIntValue(0, 1); // Terminate the directory list
 269
 270   // Second the file table.
 271   const std::vector<MCDwarfFile *> &MCDwarfFiles =
 272     MCOS->getContext().getMCDwarfFiles();
 273   for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
 274     MCOS->EmitBytes(MCDwarfFiles[i]->getName(), 0); // FileName
 275     MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
 276     // the Directory num
 277     MCOS->EmitULEB128IntValue(MCDwarfFiles[i]->getDirIndex());
 278     MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
 279     MCOS->EmitIntValue(0, 1); // filesize (always 0)
 280   }
 281   MCOS->EmitIntValue(0, 1); // Terminate the file list
 282
 283   // This is the end of the prologue, so set the value of the symbol at the
 284   // end of the prologue (that was used in a previous expression).
 285   MCOS->EmitLabel(ProEndSym);
 286
 287   // Put out the line tables.
 288   const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
 289     MCOS->getContext().getMCLineSections();
 290   const std::vector<const MCSection *> &MCLineSectionOrder =
 291     MCOS->getContext().getMCLineSectionOrder();
 292   for (std::vector<const MCSection*>::const_iterator it =
 293         MCLineSectionOrder.begin(), ie = MCLineSectionOrder.end(); it != ie;
 294        ++it) {
 295     const MCSection *Sec = *it;
 296     const MCLineSection *Line = MCLineSections.lookup(Sec);
 297     EmitDwarfLineTable(MCOS, Sec, Line);
 298
 299     // Now delete the MCLineSections that were created in MCLineEntry::Make()
 300     // and used to emit the line table.
 301     delete Line;
 302   }
 303
 304   if (MCOS->getContext().getAsmInfo().getLinkerRequiresNonEmptyDwarfLines()
 305       && MCLineSectionOrder.begin() == MCLineSectionOrder.end()) {
 306     // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
 307     // it requires:
 308     // total_length >= prologue_length + 10
 309     // We are 4 bytes short, since we have total_length = 51 and
 310     // prologue_length = 45
 311
 312     // The regular end_sequence should be sufficient.
 313     MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
 314   }
 315
 316   // This is the end of the section, so set the value of the symbol at the end
 317   // of this section (that was used in a previous expression).
 318   MCOS->EmitLabel(LineEndSym);
 319 }
 320
 321 /// Utility function to write the encoding to an object writer.
 322 void MCDwarfLineAddr::Write(MCObjectWriter *OW, int64_t LineDelta,
 323                             uint64_t AddrDelta) {
 324   SmallString<256> Tmp;
 325   raw_svector_ostream OS(Tmp);
 326   MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
 327   OW->WriteBytes(OS.str());
 328 }
 329
 330 /// Utility function to emit the encoding to a streamer.
 331 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
 332                            uint64_t AddrDelta) {
 333   SmallString<256> Tmp;
 334   raw_svector_ostream OS(Tmp);
 335   MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
 336   MCOS->EmitBytes(OS.str(), /*AddrSpace=*/0);
 337 }
 338
 339 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
 340 void MCDwarfLineAddr::Encode(int64_t LineDelta, uint64_t AddrDelta,
 341                              raw_ostream &OS) {
 342   uint64_t Temp, Opcode;
 343   bool NeedCopy = false;
 344
 345   // Scale the address delta by the minimum instruction length.
 346   AddrDelta = ScaleAddrDelta(AddrDelta);
 347
 348   // A LineDelta of INT64_MAX is a signal that this is actually a
 349   // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
 350   // end_sequence to emit the matrix entry.
 351   if (LineDelta == INT64_MAX) {
 352     if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
 353       OS << char(dwarf::DW_LNS_const_add_pc);
 354     else {
 355       OS << char(dwarf::DW_LNS_advance_pc);
 356       SmallString<32> Tmp;
 357       raw_svector_ostream OSE(Tmp);
 358       MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
 359       OS << OSE.str();
 360     }
 361     OS << char(dwarf::DW_LNS_extended_op);
 362     OS << char(1);
 363     OS << char(dwarf::DW_LNE_end_sequence);
 364     return;
 365   }
 366
 367   // Bias the line delta by the base.
 368   Temp = LineDelta - DWARF2_LINE_BASE;
 369
 370   // If the line increment is out of range of a special opcode, we must encode
 371   // it with DW_LNS_advance_line.
 372   if (Temp >= DWARF2_LINE_RANGE) {
 373     OS << char(dwarf::DW_LNS_advance_line);
 374     SmallString<32> Tmp;
 375     raw_svector_ostream OSE(Tmp);
 376     MCObjectWriter::EncodeSLEB128(LineDelta, OSE);
 377     OS << OSE.str();
 378
 379     LineDelta = 0;
 380     Temp = 0 - DWARF2_LINE_BASE;
 381     NeedCopy = true;
 382   }
 383
 384   // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
 385   if (LineDelta == 0 && AddrDelta == 0) {
 386     OS << char(dwarf::DW_LNS_copy);
 387     return;
 388   }
 389
 390   // Bias the opcode by the special opcode base.
 391   Temp += DWARF2_LINE_OPCODE_BASE;
 392
 393   // Avoid overflow when addr_delta is large.
 394   if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
 395     // Try using a special opcode.
 396     Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
 397     if (Opcode <= 255) {
 398       OS << char(Opcode);
 399       return;
 400     }
 401
 402     // Try using DW_LNS_const_add_pc followed by special op.
 403     Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
 404     if (Opcode <= 255) {
 405       OS << char(dwarf::DW_LNS_const_add_pc);
 406       OS << char(Opcode);
 407       return;
 408     }
 409   }
 410
 411   // Otherwise use DW_LNS_advance_pc.
 412   OS << char(dwarf::DW_LNS_advance_pc);
 413   SmallString<32> Tmp;
 414   raw_svector_ostream OSE(Tmp);
 415   MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
 416   OS << OSE.str();
 417
 418   if (NeedCopy)
 419     OS << char(dwarf::DW_LNS_copy);
 420   else
 421     OS << char(Temp);
 422 }
 423
 424 void MCDwarfFile::print(raw_ostream &OS) const {
 425   OS << '"' << getName() << '"';
 426 }
 427
 428 void MCDwarfFile::dump() const {
 429   print(dbgs());
 430 }
 431
 432 static int getDataAlignmentFactor(MCStreamer &streamer) {
 433   MCContext &context = streamer.getContext();
 434   const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
 435   int size = asmInfo.getPointerSize();
 436   if (asmInfo.getStackGrowthDirection() == TargetFrameLowering::StackGrowsUp)
 437     return size;
 438  else
 439    return -size;
 440 }
 441
 442 static void EmitSymbol(MCStreamer &streamer, const MCSymbol &symbol,
 443                        unsigned symbolEncoding) {
 444   MCContext &context = streamer.getContext();
 445   const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
 446   unsigned format = symbolEncoding & 0x0f;
 447   unsigned application = symbolEncoding & 0x70;
 448   unsigned size;
 449   switch (format) {
 450   default:
 451     assert(0 && "Unknown Encoding");
 452   case dwarf::DW_EH_PE_absptr:
 453   case dwarf::DW_EH_PE_signed:
 454     size = asmInfo.getPointerSize();
 455     break;
 456   case dwarf::DW_EH_PE_udata2:
 457   case dwarf::DW_EH_PE_sdata2:
 458     size = 2;
 459     break;
 460   case dwarf::DW_EH_PE_udata4:
 461   case dwarf::DW_EH_PE_sdata4:
 462     size = 4;
 463     break;
 464   case dwarf::DW_EH_PE_udata8:
 465   case dwarf::DW_EH_PE_sdata8:
 466     size = 8;
 467     break;
 468   }
 469   switch (application) {
 470   default:
 471     assert(0 && "Unknown Encoding");
 472     break;
 473   case 0:
 474     streamer.EmitSymbolValue(&symbol, size);
 475     break;
 476   case dwarf::DW_EH_PE_pcrel:
 477     streamer.EmitPCRelSymbolValue(&symbol, size);
 478     break;
 479   }
 480 }
 481
 482 static const MachineLocation TranslateMachineLocation(
 483                                                   const TargetAsmInfo &AsmInfo,
 484                                                   const MachineLocation &Loc) {
 485   unsigned Reg = Loc.getReg() == MachineLocation::VirtualFP ?
 486     MachineLocation::VirtualFP :
 487     unsigned(AsmInfo.getDwarfRegNum(Loc.getReg(), true));
 488   const MachineLocation &NewLoc = Loc.isReg() ?
 489     MachineLocation(Reg) : MachineLocation(Reg, Loc.getOffset());
 490   return NewLoc;
 491 }
 492
 493 namespace {
 494   class FrameEmitterImpl {
 495     int CFAOffset;
 496
 497   public:
 498     FrameEmitterImpl() : CFAOffset(0) {
 499     }
 500
 501     const MCSymbol &EmitCIE(MCStreamer &streamer,
 502                             const MCSymbol *personality,
 503                             unsigned personalityEncoding,
 504                             const MCSymbol *lsda,
 505                             unsigned lsdaEncoding);
 506     MCSymbol *EmitFDE(MCStreamer &streamer,
 507                       const MCSymbol &cieStart,
 508                       const MCDwarfFrameInfo &frame);
 509     void EmitCFIInstructions(MCStreamer &streamer,
 510                              const std::vector<MCCFIInstruction> &Instrs,
 511                              MCSymbol *BaseLabel);
 512     void EmitCFIInstruction(MCStreamer &Streamer,
 513                             const MCCFIInstruction &Instr);
 514   };
 515 }
 516
 517 void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
 518                                           const MCCFIInstruction &Instr) {
 519   int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
 520
 521   switch (Instr.getOperation()) {
 522   case MCCFIInstruction::Move:
 523   case MCCFIInstruction::RelMove: {
 524     const MachineLocation &Dst = Instr.getDestination();
 525     const MachineLocation &Src = Instr.getSource();
 526     const bool IsRelative = Instr.getOperation() == MCCFIInstruction::RelMove;
 527
 528     // If advancing cfa.
 529     if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
 530       assert(!Src.isReg() && "Machine move not supported yet.");
 531
 532       if (Src.getReg() == MachineLocation::VirtualFP) {
 533         Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
 534       } else {
 535         Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
 536         Streamer.EmitULEB128IntValue(Src.getReg());
 537       }
 538
 539       if (IsRelative)
 540         CFAOffset += Src.getOffset();
 541       else
 542         CFAOffset = -Src.getOffset();
 543
 544       Streamer.EmitULEB128IntValue(CFAOffset, 1);
 545       return;
 546     }
 547
 548     if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
 549       assert(Dst.isReg() && "Machine move not supported yet.");
 550       Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
 551       Streamer.EmitULEB128IntValue(Dst.getReg());
 552       return;
 553     }
 554
 555     unsigned Reg = Src.getReg();
 556
 557     int Offset = Dst.getOffset();
 558     if (IsRelative)
 559       Offset -= CFAOffset;
 560     Offset = Offset / dataAlignmentFactor;
 561
 562     if (Offset < 0) {
 563       Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
 564       Streamer.EmitULEB128IntValue(Reg);
 565       Streamer.EmitSLEB128IntValue(Offset);
 566     } else if (Reg < 64) {
 567       Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
 568       Streamer.EmitULEB128IntValue(Offset, 1);
 569     } else {
 570       Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
 571       Streamer.EmitULEB128IntValue(Reg, 1);
 572       Streamer.EmitULEB128IntValue(Offset, 1);
 573     }
 574     return;
 575   }
 576   case MCCFIInstruction::Remember:
 577     Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
 578     return;
 579   case MCCFIInstruction::Restore:
 580     Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
 581     return;
 582   case MCCFIInstruction::SameValue: {
 583     unsigned Reg = Instr.getDestination().getReg();
 584     Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
 585     Streamer.EmitULEB128IntValue(Reg, 1);
 586     return;
 587   }
 588   }
 589   llvm_unreachable("Unhandled case in switch");
 590 }
 591
 592 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
 593 /// frame.
 594 void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer,
 595                                     const std::vector<MCCFIInstruction> &Instrs,
 596                                            MCSymbol *BaseLabel) {
 597   for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
 598     const MCCFIInstruction &Instr = Instrs[i];
 599     MCSymbol *Label = Instr.getLabel();
 600     // Throw out move if the label is invalid.
 601     if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
 602
 603     // Advance row if new location.
 604     if (BaseLabel && Label) {
 605       MCSymbol *ThisSym = Label;
 606       if (ThisSym != BaseLabel) {
 607         streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
 608         BaseLabel = ThisSym;
 609       }
 610     }
 611
 612     EmitCFIInstruction(streamer, Instr);
 613   }
 614 }
 615
 616 const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
 617                                           const MCSymbol *personality,
 618                                           unsigned personalityEncoding,
 619                                           const MCSymbol *lsda,
 620                                           unsigned lsdaEncoding) {
 621   MCContext &context = streamer.getContext();
 622   const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
 623   const MCSection &section = *asmInfo.getEHFrameSection();
 624   streamer.SwitchSection(&section);
 625   MCSymbol *sectionStart = streamer.getContext().CreateTempSymbol();
 626   MCSymbol *sectionEnd = streamer.getContext().CreateTempSymbol();
 627
 628   // Length
 629   const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
 630                                                *sectionEnd, 4);
 631   streamer.EmitLabel(sectionStart);
 632   streamer.EmitValue(Length, 4);
 633
 634   // CIE ID
 635   streamer.EmitIntValue(0, 4);
 636
 637   // Version
 638   streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);
 639
 640   // Augmentation String
 641   SmallString<8> Augmentation;
 642   Augmentation += "z";
 643   if (personality)
 644     Augmentation += "P";
 645   if (lsda)
 646     Augmentation += "L";
 647   Augmentation += "R";
 648   streamer.EmitBytes(Augmentation.str(), 0);
 649   streamer.EmitIntValue(0, 1);
 650
 651   // Code Alignment Factor
 652   streamer.EmitULEB128IntValue(1);
 653
 654   // Data Alignment Factor
 655   streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));
 656
 657   // Return Address Register
 658   streamer.EmitULEB128IntValue(asmInfo.getDwarfRARegNum(true));
 659
 660   // Augmentation Data Length (optional)
 661   MCSymbol *augmentationStart = streamer.getContext().CreateTempSymbol();
 662   MCSymbol *augmentationEnd = streamer.getContext().CreateTempSymbol();
 663   const MCExpr *augmentationLength = MakeStartMinusEndExpr(streamer,
 664                                                            *augmentationStart,
 665                                                            *augmentationEnd, 0);
 666   streamer.EmitULEB128Value(augmentationLength);
 667
 668   // Augmentation Data (optional)
 669   streamer.EmitLabel(augmentationStart);
 670   if (personality) {
 671     // Personality Encoding
 672     streamer.EmitIntValue(personalityEncoding, 1);
 673     // Personality
 674     EmitSymbol(streamer, *personality, personalityEncoding);
 675   }
 676   if (lsda) {
 677     // LSDA Encoding
 678     streamer.EmitIntValue(lsdaEncoding, 1);
 679   }
 680   // Encoding of the FDE pointers
 681   streamer.EmitIntValue(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4, 1);
 682   streamer.EmitLabel(augmentationEnd);
 683
 684   // Initial Instructions
 685
 686   const std::vector<MachineMove> Moves = asmInfo.getInitialFrameState();
 687   std::vector<MCCFIInstruction> Instructions;
 688
 689   for (int i = 0, n = Moves.size(); i != n; ++i) {
 690     MCSymbol *Label = Moves[i].getLabel();
 691     const MachineLocation &Dst =
 692       TranslateMachineLocation(asmInfo, Moves[i].getDestination());
 693     const MachineLocation &Src =
 694       TranslateMachineLocation(asmInfo, Moves[i].getSource());
 695     MCCFIInstruction Inst(Label, Dst, Src);
 696     Instructions.push_back(Inst);
 697   }
 698
 699   EmitCFIInstructions(streamer, Instructions, NULL);
 700
 701   // Padding
 702   streamer.EmitValueToAlignment(4);
 703
 704   streamer.EmitLabel(sectionEnd);
 705   return *sectionStart;
 706 }
 707
 708 MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
 709                                     const MCSymbol &cieStart,
 710                                     const MCDwarfFrameInfo &frame) {
 711   MCContext &context = streamer.getContext();
 712   MCSymbol *fdeStart = context.CreateTempSymbol();
 713   MCSymbol *fdeEnd = context.CreateTempSymbol();
 714
 715   // Length
 716   const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
 717   streamer.EmitValue(Length, 4);
 718
 719   streamer.EmitLabel(fdeStart);
 720   // CIE Pointer
 721   const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
 722                                                0);
 723   streamer.EmitValue(offset, 4);
 724
 725   // PC Begin
 726   streamer.EmitPCRelSymbolValue(frame.Begin, 4);
 727
 728   // PC Range
 729   const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
 730                                               *frame.End, 0);
 731   streamer.EmitValue(Range, 4);
 732
 733   // Augmentation Data Length
 734   MCSymbol *augmentationStart = streamer.getContext().CreateTempSymbol();
 735   MCSymbol *augmentationEnd = streamer.getContext().CreateTempSymbol();
 736   const MCExpr *augmentationLength = MakeStartMinusEndExpr(streamer,
 737                                                            *augmentationStart,
 738                                                            *augmentationEnd, 0);
 739   streamer.EmitULEB128Value(augmentationLength);
 740
 741   // Augmentation Data
 742   streamer.EmitLabel(augmentationStart);
 743   if (frame.Lsda)
 744     EmitSymbol(streamer, *frame.Lsda, frame.LsdaEncoding);
 745   streamer.EmitLabel(augmentationEnd);
 746   // Call Frame Instructions
 747
 748   EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
 749
 750   // Padding
 751   streamer.EmitValueToAlignment(4);
 752
 753   return fdeEnd;
 754 }
 755
 756 namespace {
 757   struct CIEKey {
 758     static const CIEKey getEmptyKey() { return CIEKey(0, 0, -1); }
 759     static const CIEKey getTombstoneKey() { return CIEKey(0, -1, 0); }
 760
 761     CIEKey(const MCSymbol* Personality_, unsigned PersonalityEncoding_,
 762            unsigned LsdaEncoding_) : Personality(Personality_),
 763                                      PersonalityEncoding(PersonalityEncoding_),
 764                                      LsdaEncoding(LsdaEncoding_) {
 765     }
 766     const MCSymbol* Personality;
 767     unsigned PersonalityEncoding;
 768     unsigned LsdaEncoding;
 769   };
 770 }
 771
 772 namespace llvm {
 773   template <>
 774   struct DenseMapInfo<CIEKey> {
 775     static CIEKey getEmptyKey() {
 776       return CIEKey::getEmptyKey();
 777     }
 778     static CIEKey getTombstoneKey() {
 779       return CIEKey::getTombstoneKey();
 780     }
 781     static unsigned getHashValue(const CIEKey &Key) {
 782       FoldingSetNodeID ID;
 783       ID.AddPointer(Key.Personality);
 784       ID.AddInteger(Key.PersonalityEncoding);
 785       ID.AddInteger(Key.LsdaEncoding);
 786       return ID.ComputeHash();
 787     }
 788     static bool isEqual(const CIEKey &LHS,
 789                         const CIEKey &RHS) {
 790       return LHS.Personality == RHS.Personality &&
 791         LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
 792         LHS.LsdaEncoding == RHS.LsdaEncoding;
 793     }
 794   };
 795 }
 796
 797 void MCDwarfFrameEmitter::Emit(MCStreamer &streamer) {
 798   const MCContext &context = streamer.getContext();
 799   const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
 800   MCSymbol *fdeEnd = NULL;
 801   DenseMap<CIEKey, const MCSymbol*> CIEStarts;
 802   FrameEmitterImpl Emitter;
 803
 804   for (unsigned i = 0, n = streamer.getNumFrameInfos(); i < n; ++i) {
 805     const MCDwarfFrameInfo &frame = streamer.getFrameInfo(i);
 806     CIEKey key(frame.Personality, frame.PersonalityEncoding,
 807                frame.LsdaEncoding);
 808     const MCSymbol *&cieStart = CIEStarts[key];
 809     if (!cieStart)
 810       cieStart = &Emitter.EmitCIE(streamer, frame.Personality,
 811                                   frame.PersonalityEncoding, frame.Lsda,
 812                                   frame.LsdaEncoding);
 813     fdeEnd = Emitter.EmitFDE(streamer, *cieStart, frame);
 814     if (i != n - 1)
 815       streamer.EmitLabel(fdeEnd);
 816   }
 817
 818   streamer.EmitValueToAlignment(asmInfo.getPointerSize());
 819   if (fdeEnd)
 820     streamer.EmitLabel(fdeEnd);
 821 }
 822
 823 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer,
 824                                          uint64_t AddrDelta) {
 825   SmallString<256> Tmp;
 826   raw_svector_ostream OS(Tmp);
 827   MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OS);
 828   Streamer.EmitBytes(OS.str(), /*AddrSpace=*/0);
 829 }
 830
 831 void MCDwarfFrameEmitter::EncodeAdvanceLoc(uint64_t AddrDelta,
 832                                            raw_ostream &OS) {
 833   // FIXME: Assumes the code alignment factor is 1.
 834   if (AddrDelta == 0) {
 835   } else if (isUIntN(6, AddrDelta)) {
 836     uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
 837     OS << Opcode;
 838   } else if (isUInt<8>(AddrDelta)) {
 839     OS << uint8_t(dwarf::DW_CFA_advance_loc1);
 840     OS << uint8_t(AddrDelta);
 841   } else if (isUInt<16>(AddrDelta)) {
 842     // FIXME: check what is the correct behavior on a big endian machine.
 843     OS << uint8_t(dwarf::DW_CFA_advance_loc2);
 844     OS << uint8_t( AddrDelta       & 0xff);
 845     OS << uint8_t((AddrDelta >> 8) & 0xff);
 846   } else {
 847     // FIXME: check what is the correct behavior on a big endian machine.
 848     assert(isUInt<32>(AddrDelta));
 849     OS << uint8_t(dwarf::DW_CFA_advance_loc4);
 850     OS << uint8_t( AddrDelta        & 0xff);
 851     OS << uint8_t((AddrDelta >> 8)  & 0xff);
 852     OS << uint8_t((AddrDelta >> 16) & 0xff);
 853     OS << uint8_t((AddrDelta >> 24) & 0xff);
 854
 855   }
 856 }