lib/MC/MCAsmStreamer.cpp

   1 //===- lib/MC/MCAsmStreamer.cpp - Text Assembly Output --------------------===//
   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/MC/MCStreamer.h"
  11 #include "llvm/MC/MCAsmInfo.h"
  12 #include "llvm/MC/MCCodeEmitter.h"
  13 #include "llvm/MC/MCContext.h"
  14 #include "llvm/MC/MCExpr.h"
  15 #include "llvm/MC/MCInst.h"
  16 #include "llvm/MC/MCInstPrinter.h"
  17 #include "llvm/MC/MCSectionMachO.h"
  18 #include "llvm/MC/MCSymbol.h"
  19 #include "llvm/ADT/OwningPtr.h"
  20 #include "llvm/ADT/SmallString.h"
  21 #include "llvm/ADT/Twine.h"
  22 #include "llvm/Support/ErrorHandling.h"
  23 #include "llvm/Support/MathExtras.h"
  24 #include "llvm/Support/Format.h"
  25 #include "llvm/Support/FormattedStream.h"
  26 using namespace llvm;
  27
  28 namespace {
  29
  30 class MCAsmStreamer : public MCStreamer {
  31   formatted_raw_ostream &OS;
  32   const MCAsmInfo &MAI;
  33   OwningPtr<MCInstPrinter> InstPrinter;
  34   OwningPtr<MCCodeEmitter> Emitter;
  35
  36   SmallString<128> CommentToEmit;
  37   raw_svector_ostream CommentStream;
  38
  39   unsigned IsLittleEndian : 1;
  40   unsigned IsVerboseAsm : 1;
  41   unsigned ShowInst : 1;
  42
  43 public:
  44   MCAsmStreamer(MCContext &Context, formatted_raw_ostream &os,
  45                 bool isLittleEndian, bool isVerboseAsm, MCInstPrinter *printer,
  46                 MCCodeEmitter *emitter, bool showInst)
  47     : MCStreamer(Context), OS(os), MAI(Context.getAsmInfo()),
  48       InstPrinter(printer), Emitter(emitter), CommentStream(CommentToEmit),
  49       IsLittleEndian(isLittleEndian), IsVerboseAsm(isVerboseAsm),
  50       ShowInst(showInst) {
  51     if (InstPrinter && IsVerboseAsm)
  52       InstPrinter->setCommentStream(CommentStream);
  53   }
  54   ~MCAsmStreamer() {}
  55
  56   bool isLittleEndian() const { return IsLittleEndian; }
  57
  58   inline void EmitEOL() {
  59     // If we don't have any comments, just emit a \n.
  60     if (!IsVerboseAsm) {
  61       OS << '\n';
  62       return;
  63     }
  64     EmitCommentsAndEOL();
  65   }
  66   void EmitCommentsAndEOL();
  67
  68   /// isVerboseAsm - Return true if this streamer supports verbose assembly at
  69   /// all.
  70   virtual bool isVerboseAsm() const { return IsVerboseAsm; }
  71
  72   /// hasRawTextSupport - We support EmitRawText.
  73   virtual bool hasRawTextSupport() const { return true; }
  74
  75   /// AddComment - Add a comment that can be emitted to the generated .s
  76   /// file if applicable as a QoI issue to make the output of the compiler
  77   /// more readable.  This only affects the MCAsmStreamer, and only when
  78   /// verbose assembly output is enabled.
  79   virtual void AddComment(const Twine &T);
  80
  81   /// AddEncodingComment - Add a comment showing the encoding of an instruction.
  82   virtual void AddEncodingComment(const MCInst &Inst);
  83
  84   /// GetCommentOS - Return a raw_ostream that comments can be written to.
  85   /// Unlike AddComment, you are required to terminate comments with \n if you
  86   /// use this method.
  87   virtual raw_ostream &GetCommentOS() {
  88     if (!IsVerboseAsm)
  89       return nulls();  // Discard comments unless in verbose asm mode.
  90     return CommentStream;
  91   }
  92
  93   /// AddBlankLine - Emit a blank line to a .s file to pretty it up.
  94   virtual void AddBlankLine() {
  95     EmitEOL();
  96   }
  97
  98   /// @name MCStreamer Interface
  99   /// @{
 100
 101   virtual void SwitchSection(const MCSection *Section);
 102
 103   virtual void InitSections() {
 104     // FIXME, this is MachO specific, but the testsuite
 105     // expects this.
 106     SwitchSection(getContext().getMachOSection("__TEXT", "__text",
 107                          MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 108                          0, SectionKind::getText()));
 109   }
 110
 111   virtual void EmitLabel(MCSymbol *Symbol);
 112
 113   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
 114
 115   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
 116   virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol);
 117
 118   virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
 119
 120   virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
 121   virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol);
 122   virtual void EmitCOFFSymbolStorageClass(int StorageClass);
 123   virtual void EmitCOFFSymbolType(int Type);
 124   virtual void EndCOFFSymbolDef();
 125   virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value);
 126   virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 127                                 unsigned ByteAlignment);
 128
 129   /// EmitLocalCommonSymbol - Emit a local common (.lcomm) symbol.
 130   ///
 131   /// @param Symbol - The common symbol to emit.
 132   /// @param Size - The size of the common symbol.
 133   virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size);
 134
 135   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
 136                             unsigned Size = 0, unsigned ByteAlignment = 0);
 137
 138   virtual void EmitTBSSSymbol (const MCSection *Section, MCSymbol *Symbol,
 139                                uint64_t Size, unsigned ByteAlignment = 0);
 140
 141   virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
 142
 143   virtual void EmitValue(const MCExpr *Value, unsigned Size,unsigned AddrSpace);
 144
 145   virtual void EmitIntValue(uint64_t Value, unsigned Size, unsigned AddrSpace);
 146
 147   virtual void EmitULEB128Value(const MCExpr *Value, unsigned AddrSpace = 0);
 148
 149   virtual void EmitSLEB128Value(const MCExpr *Value, unsigned AddrSpace = 0);
 150
 151   virtual void EmitGPRel32Value(const MCExpr *Value);
 152
 153
 154   virtual void EmitFill(uint64_t NumBytes, uint8_t FillValue,
 155                         unsigned AddrSpace);
 156
 157   virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
 158                                     unsigned ValueSize = 1,
 159                                     unsigned MaxBytesToEmit = 0);
 160
 161   virtual void EmitCodeAlignment(unsigned ByteAlignment,
 162                                  unsigned MaxBytesToEmit = 0);
 163
 164   virtual void EmitValueToOffset(const MCExpr *Offset,
 165                                  unsigned char Value = 0);
 166
 167   virtual void EmitFileDirective(StringRef Filename);
 168   virtual void EmitDwarfFileDirective(unsigned FileNo, StringRef Filename);
 169
 170   virtual void EmitInstruction(const MCInst &Inst);
 171
 172   /// EmitRawText - If this file is backed by an assembly streamer, this dumps
 173   /// the specified string in the output .s file.  This capability is
 174   /// indicated by the hasRawTextSupport() predicate.
 175   virtual void EmitRawText(StringRef String);
 176
 177   virtual void Finish();
 178
 179   /// @}
 180 };
 181
 182 } // end anonymous namespace.
 183
 184 /// AddComment - Add a comment that can be emitted to the generated .s
 185 /// file if applicable as a QoI issue to make the output of the compiler
 186 /// more readable.  This only affects the MCAsmStreamer, and only when
 187 /// verbose assembly output is enabled.
 188 void MCAsmStreamer::AddComment(const Twine &T) {
 189   if (!IsVerboseAsm) return;
 190
 191   // Make sure that CommentStream is flushed.
 192   CommentStream.flush();
 193
 194   T.toVector(CommentToEmit);
 195   // Each comment goes on its own line.
 196   CommentToEmit.push_back('\n');
 197
 198   // Tell the comment stream that the vector changed underneath it.
 199   CommentStream.resync();
 200 }
 201
 202 void MCAsmStreamer::EmitCommentsAndEOL() {
 203   if (CommentToEmit.empty() && CommentStream.GetNumBytesInBuffer() == 0) {
 204     OS << '\n';
 205     return;
 206   }
 207
 208   CommentStream.flush();
 209   StringRef Comments = CommentToEmit.str();
 210
 211   assert(Comments.back() == '\n' &&
 212          "Comment array not newline terminated");
 213   do {
 214     // Emit a line of comments.
 215     OS.PadToColumn(MAI.getCommentColumn());
 216     size_t Position = Comments.find('\n');
 217     OS << MAI.getCommentString() << ' ' << Comments.substr(0, Position) << '\n';
 218
 219     Comments = Comments.substr(Position+1);
 220   } while (!Comments.empty());
 221
 222   CommentToEmit.clear();
 223   // Tell the comment stream that the vector changed underneath it.
 224   CommentStream.resync();
 225 }
 226
 227 static inline int64_t truncateToSize(int64_t Value, unsigned Bytes) {
 228   assert(Bytes && "Invalid size!");
 229   return Value & ((uint64_t) (int64_t) -1 >> (64 - Bytes * 8));
 230 }
 231
 232 void MCAsmStreamer::SwitchSection(const MCSection *Section) {
 233   assert(Section && "Cannot switch to a null section!");
 234   if (Section != CurSection) {
 235     PrevSection = CurSection;
 236     CurSection = Section;
 237     Section->PrintSwitchToSection(MAI, OS);
 238   }
 239 }
 240
 241 void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
 242   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
 243   assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
 244   assert(CurSection && "Cannot emit before setting section!");
 245
 246   OS << *Symbol << MAI.getLabelSuffix();
 247   EmitEOL();
 248   Symbol->setSection(*CurSection);
 249 }
 250
 251 void MCAsmStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
 252   switch (Flag) {
 253   default: assert(0 && "Invalid flag!");
 254   case MCAF_SyntaxUnified:         OS << "\t.syntax unified"; break;
 255   case MCAF_SubsectionsViaSymbols: OS << ".subsections_via_symbols"; break;
 256   }
 257   EmitEOL();
 258 }
 259
 260 void MCAsmStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
 261   OS << *Symbol << " = " << *Value;
 262   EmitEOL();
 263
 264   // FIXME: Lift context changes into super class.
 265   Symbol->setVariableValue(Value);
 266 }
 267
 268 void MCAsmStreamer::EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {
 269   OS << ".weakref " << *Alias << ", " << *Symbol;
 270   EmitEOL();
 271 }
 272
 273 void MCAsmStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
 274                                         MCSymbolAttr Attribute) {
 275   switch (Attribute) {
 276   case MCSA_Invalid: assert(0 && "Invalid symbol attribute");
 277   case MCSA_ELF_TypeFunction:    /// .type _foo, STT_FUNC  # aka @function
 278   case MCSA_ELF_TypeIndFunction: /// .type _foo, STT_GNU_IFUNC
 279   case MCSA_ELF_TypeObject:      /// .type _foo, STT_OBJECT  # aka @object
 280   case MCSA_ELF_TypeTLS:         /// .type _foo, STT_TLS     # aka @tls_object
 281   case MCSA_ELF_TypeCommon:      /// .type _foo, STT_COMMON  # aka @common
 282   case MCSA_ELF_TypeNoType:      /// .type _foo, STT_NOTYPE  # aka @notype
 283     assert(MAI.hasDotTypeDotSizeDirective() && "Symbol Attr not supported");
 284     OS << "\t.type\t" << *Symbol << ','
 285        << ((MAI.getCommentString()[0] != '@') ? '@' : '%');
 286     switch (Attribute) {
 287     default: assert(0 && "Unknown ELF .type");
 288     case MCSA_ELF_TypeFunction:    OS << "function"; break;
 289     case MCSA_ELF_TypeIndFunction: OS << "gnu_indirect_function"; break;
 290     case MCSA_ELF_TypeObject:      OS << "object"; break;
 291     case MCSA_ELF_TypeTLS:         OS << "tls_object"; break;
 292     case MCSA_ELF_TypeCommon:      OS << "common"; break;
 293     case MCSA_ELF_TypeNoType:      OS << "no_type"; break;
 294     }
 295     EmitEOL();
 296     return;
 297   case MCSA_Global: // .globl/.global
 298     OS << MAI.getGlobalDirective();
 299     break;
 300   case MCSA_Hidden:         OS << "\t.hidden\t";          break;
 301   case MCSA_IndirectSymbol: OS << "\t.indirect_symbol\t"; break;
 302   case MCSA_Internal:       OS << "\t.internal\t";        break;
 303   case MCSA_LazyReference:  OS << "\t.lazy_reference\t";  break;
 304   case MCSA_Local:          OS << "\t.local\t";           break;
 305   case MCSA_NoDeadStrip:    OS << "\t.no_dead_strip\t";   break;
 306   case MCSA_PrivateExtern:  OS << "\t.private_extern\t";  break;
 307   case MCSA_Protected:      OS << "\t.protected\t";       break;
 308   case MCSA_Reference:      OS << "\t.reference\t";       break;
 309   case MCSA_Weak:           OS << "\t.weak\t";            break;
 310   case MCSA_WeakDefinition: OS << "\t.weak_definition\t"; break;
 311       // .weak_reference
 312   case MCSA_WeakReference:  OS << MAI.getWeakRefDirective(); break;
 313   case MCSA_WeakDefAutoPrivate: OS << "\t.weak_def_can_be_hidden\t"; break;
 314   }
 315
 316   OS << *Symbol;
 317   EmitEOL();
 318 }
 319
 320 void MCAsmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
 321   OS << ".desc" << ' ' << *Symbol << ',' << DescValue;
 322   EmitEOL();
 323 }
 324
 325 void MCAsmStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {
 326   OS << "\t.def\t " << *Symbol << ';';
 327   EmitEOL();
 328 }
 329
 330 void MCAsmStreamer::EmitCOFFSymbolStorageClass (int StorageClass) {
 331   OS << "\t.scl\t" << StorageClass << ';';
 332   EmitEOL();
 333 }
 334
 335 void MCAsmStreamer::EmitCOFFSymbolType (int Type) {
 336   OS << "\t.type\t" << Type << ';';
 337   EmitEOL();
 338 }
 339
 340 void MCAsmStreamer::EndCOFFSymbolDef() {
 341   OS << "\t.endef";
 342   EmitEOL();
 343 }
 344
 345 void MCAsmStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
 346   assert(MAI.hasDotTypeDotSizeDirective());
 347   OS << "\t.size\t" << *Symbol << ", " << *Value << '\n';
 348 }
 349
 350 void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 351                                      unsigned ByteAlignment) {
 352   OS << "\t.comm\t" << *Symbol << ',' << Size;
 353   if (ByteAlignment != 0) {
 354     if (MAI.getCOMMDirectiveAlignmentIsInBytes())
 355       OS << ',' << ByteAlignment;
 356     else
 357       OS << ',' << Log2_32(ByteAlignment);
 358   }
 359   EmitEOL();
 360 }
 361
 362 /// EmitLocalCommonSymbol - Emit a local common (.lcomm) symbol.
 363 ///
 364 /// @param Symbol - The common symbol to emit.
 365 /// @param Size - The size of the common symbol.
 366 void MCAsmStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
 367   assert(MAI.hasLCOMMDirective() && "Doesn't have .lcomm, can't emit it!");
 368   OS << "\t.lcomm\t" << *Symbol << ',' << Size;
 369   EmitEOL();
 370 }
 371
 372 void MCAsmStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
 373                                  unsigned Size, unsigned ByteAlignment) {
 374   // Note: a .zerofill directive does not switch sections.
 375   OS << ".zerofill ";
 376
 377   // This is a mach-o specific directive.
 378   const MCSectionMachO *MOSection = ((const MCSectionMachO*)Section);
 379   OS << MOSection->getSegmentName() << "," << MOSection->getSectionName();
 380
 381   if (Symbol != NULL) {
 382     OS << ',' << *Symbol << ',' << Size;
 383     if (ByteAlignment != 0)
 384       OS << ',' << Log2_32(ByteAlignment);
 385   }
 386   EmitEOL();
 387 }
 388
 389 // .tbss sym, size, align
 390 // This depends that the symbol has already been mangled from the original,
 391 // e.g. _a.
 392 void MCAsmStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
 393                                    uint64_t Size, unsigned ByteAlignment) {
 394   assert(Symbol != NULL && "Symbol shouldn't be NULL!");
 395   // Instead of using the Section we'll just use the shortcut.
 396   // This is a mach-o specific directive and section.
 397   OS << ".tbss " << *Symbol << ", " << Size;
 398
 399   // Output align if we have it.  We default to 1 so don't bother printing
 400   // that.
 401   if (ByteAlignment > 1) OS << ", " << Log2_32(ByteAlignment);
 402
 403   EmitEOL();
 404 }
 405
 406 static inline char toOctal(int X) { return (X&7)+'0'; }
 407
 408 static void PrintQuotedString(StringRef Data, raw_ostream &OS) {
 409   OS << '"';
 410
 411   for (unsigned i = 0, e = Data.size(); i != e; ++i) {
 412     unsigned char C = Data[i];
 413     if (C == '"' || C == '\\') {
 414       OS << '\\' << (char)C;
 415       continue;
 416     }
 417
 418     if (isprint((unsigned char)C)) {
 419       OS << (char)C;
 420       continue;
 421     }
 422
 423     switch (C) {
 424       case '\b': OS << "\\b"; break;
 425       case '\f': OS << "\\f"; break;
 426       case '\n': OS << "\\n"; break;
 427       case '\r': OS << "\\r"; break;
 428       case '\t': OS << "\\t"; break;
 429       default:
 430         OS << '\\';
 431         OS << toOctal(C >> 6);
 432         OS << toOctal(C >> 3);
 433         OS << toOctal(C >> 0);
 434         break;
 435     }
 436   }
 437
 438   OS << '"';
 439 }
 440
 441
 442 void MCAsmStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
 443   assert(CurSection && "Cannot emit contents before setting section!");
 444   if (Data.empty()) return;
 445
 446   if (Data.size() == 1) {
 447     OS << MAI.getData8bitsDirective(AddrSpace);
 448     OS << (unsigned)(unsigned char)Data[0];
 449     EmitEOL();
 450     return;
 451   }
 452
 453   // If the data ends with 0 and the target supports .asciz, use it, otherwise
 454   // use .ascii
 455   if (MAI.getAscizDirective() && Data.back() == 0) {
 456     OS << MAI.getAscizDirective();
 457     Data = Data.substr(0, Data.size()-1);
 458   } else {
 459     OS << MAI.getAsciiDirective();
 460   }
 461
 462   OS << ' ';
 463   PrintQuotedString(Data, OS);
 464   EmitEOL();
 465 }
 466
 467 /// EmitIntValue - Special case of EmitValue that avoids the client having
 468 /// to pass in a MCExpr for constant integers.
 469 void MCAsmStreamer::EmitIntValue(uint64_t Value, unsigned Size,
 470                                  unsigned AddrSpace) {
 471   assert(CurSection && "Cannot emit contents before setting section!");
 472   const char *Directive = 0;
 473   switch (Size) {
 474   default: break;
 475   case 1: Directive = MAI.getData8bitsDirective(AddrSpace); break;
 476   case 2: Directive = MAI.getData16bitsDirective(AddrSpace); break;
 477   case 4: Directive = MAI.getData32bitsDirective(AddrSpace); break;
 478   case 8:
 479     Directive = MAI.getData64bitsDirective(AddrSpace);
 480     // If the target doesn't support 64-bit data, emit as two 32-bit halves.
 481     if (Directive) break;
 482     if (isLittleEndian()) {
 483       EmitIntValue((uint32_t)(Value >> 0 ), 4, AddrSpace);
 484       EmitIntValue((uint32_t)(Value >> 32), 4, AddrSpace);
 485     } else {
 486       EmitIntValue((uint32_t)(Value >> 32), 4, AddrSpace);
 487       EmitIntValue((uint32_t)(Value >> 0 ), 4, AddrSpace);
 488     }
 489     return;
 490   }
 491
 492   assert(Directive && "Invalid size for machine code value!");
 493   OS << Directive << truncateToSize(Value, Size);
 494   EmitEOL();
 495 }
 496
 497 void MCAsmStreamer::EmitValue(const MCExpr *Value, unsigned Size,
 498                               unsigned AddrSpace) {
 499   assert(CurSection && "Cannot emit contents before setting section!");
 500   const char *Directive = 0;
 501   switch (Size) {
 502   default: break;
 503   case 1: Directive = MAI.getData8bitsDirective(AddrSpace); break;
 504   case 2: Directive = MAI.getData16bitsDirective(AddrSpace); break;
 505   case 4: Directive = MAI.getData32bitsDirective(AddrSpace); break;
 506   case 8: Directive = MAI.getData64bitsDirective(AddrSpace); break;
 507   }
 508
 509   assert(Directive && "Invalid size for machine code value!");
 510   OS << Directive << *Value;
 511   EmitEOL();
 512 }
 513
 514 void MCAsmStreamer::EmitULEB128Value(const MCExpr *Value, unsigned AddrSpace) {
 515   OS << ".uleb " << *Value;
 516   EmitEOL();
 517 }
 518
 519 void MCAsmStreamer::EmitSLEB128Value(const MCExpr *Value, unsigned AddrSpace) {
 520   OS << ".sleb " << *Value;
 521   EmitEOL();
 522 }
 523
 524 void MCAsmStreamer::EmitGPRel32Value(const MCExpr *Value) {
 525   assert(MAI.getGPRel32Directive() != 0);
 526   OS << MAI.getGPRel32Directive() << *Value;
 527   EmitEOL();
 528 }
 529
 530
 531 /// EmitFill - Emit NumBytes bytes worth of the value specified by
 532 /// FillValue.  This implements directives such as '.space'.
 533 void MCAsmStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue,
 534                              unsigned AddrSpace) {
 535   if (NumBytes == 0) return;
 536
 537   if (AddrSpace == 0)
 538     if (const char *ZeroDirective = MAI.getZeroDirective()) {
 539       OS << ZeroDirective << NumBytes;
 540       if (FillValue != 0)
 541         OS << ',' << (int)FillValue;
 542       EmitEOL();
 543       return;
 544     }
 545
 546   // Emit a byte at a time.
 547   MCStreamer::EmitFill(NumBytes, FillValue, AddrSpace);
 548 }
 549
 550 void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
 551                                          unsigned ValueSize,
 552                                          unsigned MaxBytesToEmit) {
 553   // Some assemblers don't support non-power of two alignments, so we always
 554   // emit alignments as a power of two if possible.
 555   if (isPowerOf2_32(ByteAlignment)) {
 556     switch (ValueSize) {
 557     default: llvm_unreachable("Invalid size for machine code value!");
 558     case 1: OS << MAI.getAlignDirective(); break;
 559     // FIXME: use MAI for this!
 560     case 2: OS << ".p2alignw "; break;
 561     case 4: OS << ".p2alignl "; break;
 562     case 8: llvm_unreachable("Unsupported alignment size!");
 563     }
 564
 565     if (MAI.getAlignmentIsInBytes())
 566       OS << ByteAlignment;
 567     else
 568       OS << Log2_32(ByteAlignment);
 569
 570     if (Value || MaxBytesToEmit) {
 571       OS << ", 0x";
 572       OS.write_hex(truncateToSize(Value, ValueSize));
 573
 574       if (MaxBytesToEmit)
 575         OS << ", " << MaxBytesToEmit;
 576     }
 577     EmitEOL();
 578     return;
 579   }
 580
 581   // Non-power of two alignment.  This is not widely supported by assemblers.
 582   // FIXME: Parameterize this based on MAI.
 583   switch (ValueSize) {
 584   default: llvm_unreachable("Invalid size for machine code value!");
 585   case 1: OS << ".balign";  break;
 586   case 2: OS << ".balignw"; break;
 587   case 4: OS << ".balignl"; break;
 588   case 8: llvm_unreachable("Unsupported alignment size!");
 589   }
 590
 591   OS << ' ' << ByteAlignment;
 592   OS << ", " << truncateToSize(Value, ValueSize);
 593   if (MaxBytesToEmit)
 594     OS << ", " << MaxBytesToEmit;
 595   EmitEOL();
 596 }
 597
 598 void MCAsmStreamer::EmitCodeAlignment(unsigned ByteAlignment,
 599                                       unsigned MaxBytesToEmit) {
 600   // Emit with a text fill value.
 601   EmitValueToAlignment(ByteAlignment, MAI.getTextAlignFillValue(),
 602                        1, MaxBytesToEmit);
 603 }
 604
 605 void MCAsmStreamer::EmitValueToOffset(const MCExpr *Offset,
 606                                       unsigned char Value) {
 607   // FIXME: Verify that Offset is associated with the current section.
 608   OS << ".org " << *Offset << ", " << (unsigned) Value;
 609   EmitEOL();
 610 }
 611
 612
 613 void MCAsmStreamer::EmitFileDirective(StringRef Filename) {
 614   assert(MAI.hasSingleParameterDotFile());
 615   OS << "\t.file\t";
 616   PrintQuotedString(Filename, OS);
 617   EmitEOL();
 618 }
 619
 620 void MCAsmStreamer::EmitDwarfFileDirective(unsigned FileNo, StringRef Filename){
 621   OS << "\t.file\t" << FileNo << ' ';
 622   PrintQuotedString(Filename, OS);
 623   EmitEOL();
 624 }
 625
 626 void MCAsmStreamer::AddEncodingComment(const MCInst &Inst) {
 627   raw_ostream &OS = GetCommentOS();
 628   SmallString<256> Code;
 629   SmallVector<MCFixup, 4> Fixups;
 630   raw_svector_ostream VecOS(Code);
 631   Emitter->EncodeInstruction(Inst, VecOS, Fixups);
 632   VecOS.flush();
 633
 634   // If we are showing fixups, create symbolic markers in the encoded
 635   // representation. We do this by making a per-bit map to the fixup item index,
 636   // then trying to display it as nicely as possible.
 637   SmallVector<uint8_t, 64> FixupMap;
 638   FixupMap.resize(Code.size() * 8);
 639   for (unsigned i = 0, e = Code.size() * 8; i != e; ++i)
 640     FixupMap[i] = 0;
 641
 642   for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
 643     MCFixup &F = Fixups[i];
 644     const MCFixupKindInfo &Info = Emitter->getFixupKindInfo(F.getKind());
 645     for (unsigned j = 0; j != Info.TargetSize; ++j) {
 646       unsigned Index = F.getOffset() * 8 + Info.TargetOffset + j;
 647       assert(Index < Code.size() * 8 && "Invalid offset in fixup!");
 648       FixupMap[Index] = 1 + i;
 649     }
 650   }
 651
 652   OS << "encoding: [";
 653   for (unsigned i = 0, e = Code.size(); i != e; ++i) {
 654     if (i)
 655       OS << ',';
 656
 657     // See if all bits are the same map entry.
 658     uint8_t MapEntry = FixupMap[i * 8 + 0];
 659     for (unsigned j = 1; j != 8; ++j) {
 660       if (FixupMap[i * 8 + j] == MapEntry)
 661         continue;
 662
 663       MapEntry = uint8_t(~0U);
 664       break;
 665     }
 666
 667     if (MapEntry != uint8_t(~0U)) {
 668       if (MapEntry == 0) {
 669         OS << format("0x%02x", uint8_t(Code[i]));
 670       } else {
 671         assert(Code[i] == 0 && "Encoder wrote into fixed up bit!");
 672         OS << char('A' + MapEntry - 1);
 673       }
 674     } else {
 675       // Otherwise, write out in binary.
 676       OS << "0b";
 677       for (unsigned j = 8; j--;) {
 678         unsigned Bit = (Code[i] >> j) & 1;
 679         if (uint8_t MapEntry = FixupMap[i * 8 + j]) {
 680           assert(Bit == 0 && "Encoder wrote into fixed up bit!");
 681           OS << char('A' + MapEntry - 1);
 682         } else
 683           OS << Bit;
 684       }
 685     }
 686   }
 687   OS << "]\n";
 688
 689   for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
 690     MCFixup &F = Fixups[i];
 691     const MCFixupKindInfo &Info = Emitter->getFixupKindInfo(F.getKind());
 692     OS << "  fixup " << char('A' + i) << " - " << "offset: " << F.getOffset()
 693        << ", value: " << *F.getValue() << ", kind: " << Info.Name << "\n";
 694   }
 695 }
 696
 697 void MCAsmStreamer::EmitInstruction(const MCInst &Inst) {
 698   assert(CurSection && "Cannot emit contents before setting section!");
 699
 700   // Show the encoding in a comment if we have a code emitter.
 701   if (Emitter)
 702     AddEncodingComment(Inst);
 703
 704   // Show the MCInst if enabled.
 705   if (ShowInst) {
 706     Inst.dump_pretty(GetCommentOS(), &MAI, InstPrinter.get(), "\n ");
 707     GetCommentOS() << "\n";
 708   }
 709
 710   // If we have an AsmPrinter, use that to print, otherwise print the MCInst.
 711   if (InstPrinter)
 712     InstPrinter->printInst(&Inst, OS);
 713   else
 714     Inst.print(OS, &MAI);
 715   EmitEOL();
 716 }
 717
 718 /// EmitRawText - If this file is backed by an assembly streamer, this dumps
 719 /// the specified string in the output .s file.  This capability is
 720 /// indicated by the hasRawTextSupport() predicate.
 721 void MCAsmStreamer::EmitRawText(StringRef String) {
 722   if (!String.empty() && String.back() == '\n')
 723     String = String.substr(0, String.size()-1);
 724   OS << String;
 725   EmitEOL();
 726 }
 727
 728 void MCAsmStreamer::Finish() {
 729 }
 730
 731 MCStreamer *llvm::createAsmStreamer(MCContext &Context,
 732                                     formatted_raw_ostream &OS,
 733                                     bool isLittleEndian,
 734                                     bool isVerboseAsm, MCInstPrinter *IP,
 735                                     MCCodeEmitter *CE, bool ShowInst) {
 736   return new MCAsmStreamer(Context, OS, isLittleEndian, isVerboseAsm,
 737                            IP, CE, ShowInst);
 738 }