lib/MC/WinCOFFStreamer.cpp

   1 //===-- llvm/MC/WinCOFFStreamer.cpp -----------------------------*- C++ -*-===//
   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 // This file contains an implementation of a Win32 COFF object file streamer.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #define DEBUG_TYPE "WinCOFFStreamer"
  15
  16 #include "llvm/MC/MCObjectStreamer.h"
  17 #include "llvm/MC/MCContext.h"
  18 #include "llvm/MC/MCSection.h"
  19 #include "llvm/MC/MCSymbol.h"
  20 #include "llvm/MC/MCExpr.h"
  21 #include "llvm/MC/MCValue.h"
  22 #include "llvm/MC/MCAssembler.h"
  23 #include "llvm/MC/MCAsmLayout.h"
  24 #include "llvm/MC/MCCodeEmitter.h"
  25 #include "llvm/MC/MCSectionCOFF.h"
  26 #include "llvm/Target/TargetRegistry.h"
  27 #include "llvm/Target/TargetAsmBackend.h"
  28 #include "llvm/ADT/StringMap.h"
  29
  30 #include "llvm/Support/COFF.h"
  31 #include "llvm/Support/Debug.h"
  32 #include "llvm/Support/ErrorHandling.h"
  33 #include "llvm/Support/raw_ostream.h"
  34 using namespace llvm;
  35
  36 namespace {
  37 class WinCOFFStreamer : public MCObjectStreamer {
  38 public:
  39   MCSymbol const *CurSymbol;
  40
  41   WinCOFFStreamer(MCContext &Context,
  42                   TargetAsmBackend &TAB,
  43                   MCCodeEmitter &CE,
  44                   raw_ostream &OS);
  45
  46   void AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
  47                        unsigned ByteAlignment, bool External);
  48
  49   // MCStreamer interface
  50
  51   virtual void InitSections();
  52   virtual void EmitLabel(MCSymbol *Symbol);
  53   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
  54   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
  55   virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
  56   virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
  57   virtual void BeginCOFFSymbolDef(MCSymbol const *Symbol);
  58   virtual void EmitCOFFSymbolStorageClass(int StorageClass);
  59   virtual void EmitCOFFSymbolType(int Type);
  60   virtual void EndCOFFSymbolDef();
  61   virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value);
  62   virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
  63                                 unsigned ByteAlignment);
  64   virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size);
  65   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
  66                             unsigned Size,unsigned ByteAlignment);
  67   virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
  68                               uint64_t Size, unsigned ByteAlignment);
  69   virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
  70   virtual void EmitValue(const MCExpr *Value, unsigned Size,
  71                          unsigned AddrSpace);
  72   virtual void EmitGPRel32Value(const MCExpr *Value);
  73   virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
  74                                    unsigned ValueSize, unsigned MaxBytesToEmit);
  75   virtual void EmitCodeAlignment(unsigned ByteAlignment,
  76                                  unsigned MaxBytesToEmit);
  77   virtual void EmitValueToOffset(const MCExpr *Offset, unsigned char Value);
  78   virtual void EmitFileDirective(StringRef Filename);
  79   virtual void EmitDwarfFileDirective(unsigned FileNo,StringRef Filename);
  80   virtual void EmitInstruction(const MCInst &Instruction);
  81   virtual void Finish();
  82
  83 private:
  84   virtual void EmitInstToFragment(const MCInst &Inst) {
  85     llvm_unreachable("Not used by WinCOFF.");
  86   }
  87   virtual void EmitInstToData(const MCInst &Inst) {
  88     llvm_unreachable("Not used by WinCOFF.");
  89   }
  90
  91   void SetSection(StringRef Section,
  92                   unsigned Characteristics,
  93                   SectionKind Kind) {
  94     SwitchSection(getContext().getCOFFSection(Section, Characteristics, Kind));
  95   }
  96
  97   void SetSectionText() {
  98     SetSection(".text",
  99                COFF::IMAGE_SCN_CNT_CODE
 100              | COFF::IMAGE_SCN_MEM_EXECUTE
 101              | COFF::IMAGE_SCN_MEM_READ,
 102                SectionKind::getText());
 103     EmitCodeAlignment(4, 0);
 104   }
 105
 106   void SetSectionData() {
 107     SetSection(".data",
 108                COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
 109              | COFF::IMAGE_SCN_MEM_READ
 110              | COFF::IMAGE_SCN_MEM_WRITE,
 111                SectionKind::getDataRel());
 112     EmitCodeAlignment(4, 0);
 113   }
 114
 115   void SetSectionBSS() {
 116     SetSection(".bss",
 117                COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA
 118              | COFF::IMAGE_SCN_MEM_READ
 119              | COFF::IMAGE_SCN_MEM_WRITE,
 120                SectionKind::getBSS());
 121     EmitCodeAlignment(4, 0);
 122   }
 123
 124 };
 125 } // end anonymous namespace.
 126
 127 WinCOFFStreamer::WinCOFFStreamer(MCContext &Context,
 128                                  TargetAsmBackend &TAB,
 129                                  MCCodeEmitter &CE,
 130                                  raw_ostream &OS)
 131     : MCObjectStreamer(Context, TAB, OS, &CE, true)
 132     , CurSymbol(NULL) {
 133 }
 134
 135 void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 136                                       unsigned ByteAlignment, bool External) {
 137   assert(!Symbol->isInSection() && "Symbol must not already have a section!");
 138
 139   std::string SectionName(".bss$linkonce");
 140   SectionName.append(Symbol->getName().begin(), Symbol->getName().end());
 141
 142   MCSymbolData &SymbolData = getAssembler().getOrCreateSymbolData(*Symbol);
 143
 144   unsigned Characteristics =
 145     COFF::IMAGE_SCN_LNK_COMDAT |
 146     COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
 147     COFF::IMAGE_SCN_MEM_READ |
 148     COFF::IMAGE_SCN_MEM_WRITE;
 149
 150   int Selection = COFF::IMAGE_COMDAT_SELECT_LARGEST;
 151
 152   const MCSection *Section = MCStreamer::getContext().getCOFFSection(
 153     SectionName, Characteristics, Selection, SectionKind::getBSS());
 154
 155   MCSectionData &SectionData = getAssembler().getOrCreateSectionData(*Section);
 156
 157   if (SectionData.getAlignment() < ByteAlignment)
 158     SectionData.setAlignment(ByteAlignment);
 159
 160   SymbolData.setExternal(External);
 161
 162   Symbol->setSection(*Section);
 163
 164   if (ByteAlignment != 1)
 165       new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectionData);
 166
 167   SymbolData.setFragment(new MCFillFragment(0, 0, Size, &SectionData));
 168 }
 169
 170 // MCStreamer interface
 171
 172 void WinCOFFStreamer::InitSections() {
 173   SetSectionText();
 174   SetSectionData();
 175   SetSectionBSS();
 176   SetSectionText();
 177 }
 178
 179 void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
 180   // TODO: This is copied almost exactly from the MachOStreamer. Consider
 181   // merging into MCObjectStreamer?
 182   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
 183   assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
 184   assert(CurSection && "Cannot emit before setting section!");
 185
 186   Symbol->setSection(*CurSection);
 187
 188   MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
 189
 190   // FIXME: This is wasteful, we don't necessarily need to create a data
 191   // fragment. Instead, we should mark the symbol as pointing into the data
 192   // fragment if it exists, otherwise we should just queue the label and set its
 193   // fragment pointer when we emit the next fragment.
 194   MCDataFragment *DF = getOrCreateDataFragment();
 195
 196   assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
 197   SD.setFragment(DF);
 198   SD.setOffset(DF->getContents().size());
 199 }
 200
 201 void WinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
 202   llvm_unreachable("not implemented");
 203 }
 204
 205 void WinCOFFStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
 206   assert((Symbol->isInSection()
 207          ? Symbol->getSection().getVariant() == MCSection::SV_COFF
 208          : true) && "Got non COFF section in the COFF backend!");
 209   // FIXME: This is all very ugly and depressing. What needs to happen here
 210   // depends on quite a few things that are all part of relaxation, which we
 211   // don't really even do.
 212
 213   if (Value->getKind() != MCExpr::SymbolRef) {
 214     // TODO: This is exactly the same as MachOStreamer. Consider merging into
 215     // MCObjectStreamer.
 216     getAssembler().getOrCreateSymbolData(*Symbol);
 217     AddValueSymbols(Value);
 218     Symbol->setVariableValue(Value);
 219   } else {
 220     // FIXME: This is a horrible way to do this :(. This should really be
 221     // handled after we are done with the MC* objects and immediately before
 222     // writing out the object file when we know exactly what the symbol should
 223     // look like in the coff symbol table. I'm not doing that now because the
 224     // COFF object writer doesn't have a clearly defined separation between MC
 225     // data structures, the object writers data structures, and the raw, POD,
 226     // data structures that get written to disk.
 227
 228     // Copy over the aliased data.
 229     MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
 230     const MCSymbolData &RealSD = getAssembler().getOrCreateSymbolData(
 231       dyn_cast<const MCSymbolRefExpr>(Value)->getSymbol());
 232
 233     // FIXME: This is particularly nasty because it breaks as soon as any data
 234     // members of MCSymbolData change.
 235     SD.CommonAlign     = RealSD.CommonAlign;
 236     SD.CommonSize      = RealSD.CommonSize;
 237     SD.Flags           = RealSD.Flags;
 238     SD.Fragment        = RealSD.Fragment;
 239     SD.Index           = RealSD.Index;
 240     SD.IsExternal      = RealSD.IsExternal;
 241     SD.IsPrivateExtern = RealSD.IsPrivateExtern;
 242     SD.Offset          = RealSD.Offset;
 243     SD.SymbolSize      = RealSD.SymbolSize;
 244   }
 245 }
 246
 247 void WinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
 248                                           MCSymbolAttr Attribute) {
 249   assert(Symbol && "Symbol must be non-null!");
 250   assert((Symbol->isInSection()
 251          ? Symbol->getSection().getVariant() == MCSection::SV_COFF
 252          : true) && "Got non COFF section in the COFF backend!");
 253   switch (Attribute) {
 254   case MCSA_WeakReference:
 255   case MCSA_Weak: {
 256       MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
 257       SD.modifyFlags(COFF::SF_WeakExternal, COFF::SF_WeakExternal);
 258       SD.setExternal(true);
 259     }
 260     break;
 261
 262   case MCSA_Global:
 263     getAssembler().getOrCreateSymbolData(*Symbol).setExternal(true);
 264     break;
 265
 266   default:
 267     llvm_unreachable("unsupported attribute");
 268     break;
 269   }
 270 }
 271
 272 void WinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
 273   llvm_unreachable("not implemented");
 274 }
 275
 276 void WinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) {
 277   assert((Symbol->isInSection()
 278          ? Symbol->getSection().getVariant() == MCSection::SV_COFF
 279          : true) && "Got non COFF section in the COFF backend!");
 280   assert(CurSymbol == NULL && "EndCOFFSymbolDef must be called between calls "
 281                               "to BeginCOFFSymbolDef!");
 282   CurSymbol = Symbol;
 283 }
 284
 285 void WinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
 286   assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
 287   assert((StorageClass & ~0xFF) == 0 && "StorageClass must only have data in "
 288                                         "the first byte!");
 289
 290   getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
 291     StorageClass << COFF::SF_ClassShift,
 292     COFF::SF_ClassMask);
 293 }
 294
 295 void WinCOFFStreamer::EmitCOFFSymbolType(int Type) {
 296   assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
 297   assert((Type & ~0xFFFF) == 0 && "Type must only have data in the first 2 "
 298                                   "bytes");
 299
 300   getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
 301     Type << COFF::SF_TypeShift,
 302     COFF::SF_TypeMask);
 303 }
 304
 305 void WinCOFFStreamer::EndCOFFSymbolDef() {
 306   assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
 307   CurSymbol = NULL;
 308 }
 309
 310 void WinCOFFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
 311   llvm_unreachable("not implemented");
 312 }
 313
 314 void WinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 315                                        unsigned ByteAlignment) {
 316   assert((Symbol->isInSection()
 317          ? Symbol->getSection().getVariant() == MCSection::SV_COFF
 318          : true) && "Got non COFF section in the COFF backend!");
 319   AddCommonSymbol(Symbol, Size, ByteAlignment, true);
 320 }
 321
 322 void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
 323   assert((Symbol->isInSection()
 324          ? Symbol->getSection().getVariant() == MCSection::SV_COFF
 325          : true) && "Got non COFF section in the COFF backend!");
 326   AddCommonSymbol(Symbol, Size, 1, false);
 327 }
 328
 329 void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
 330                                    unsigned Size,unsigned ByteAlignment) {
 331   llvm_unreachable("not implemented");
 332 }
 333
 334 void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
 335                                      uint64_t Size, unsigned ByteAlignment) {
 336   llvm_unreachable("not implemented");
 337 }
 338
 339 void WinCOFFStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
 340   // TODO: This is copied exactly from the MachOStreamer. Consider merging into
 341   // MCObjectStreamer?
 342   getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
 343 }
 344
 345 void WinCOFFStreamer::EmitValue(const MCExpr *Value, unsigned Size,
 346                                 unsigned AddrSpace) {
 347   assert(AddrSpace == 0 && "Address space must be 0!");
 348
 349   // TODO: This is copied exactly from the MachOStreamer. Consider merging into
 350   // MCObjectStreamer?
 351   MCDataFragment *DF = getOrCreateDataFragment();
 352
 353   // Avoid fixups when possible.
 354   int64_t AbsValue;
 355   if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
 356     // FIXME: Endianness assumption.
 357     for (unsigned i = 0; i != Size; ++i)
 358       DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
 359   } else {
 360     DF->addFixup(MCFixup::Create(DF->getContents().size(),
 361                                  AddValueSymbols(Value),
 362                                  MCFixup::getKindForSize(Size)));
 363     DF->getContents().resize(DF->getContents().size() + Size, 0);
 364   }
 365 }
 366
 367 void WinCOFFStreamer::EmitGPRel32Value(const MCExpr *Value) {
 368   llvm_unreachable("not implemented");
 369 }
 370
 371 void WinCOFFStreamer::EmitValueToAlignment(unsigned ByteAlignment,
 372                                            int64_t Value,
 373                                            unsigned ValueSize,
 374                                            unsigned MaxBytesToEmit) {
 375   // TODO: This is copied exactly from the MachOStreamer. Consider merging into
 376   // MCObjectStreamer?
 377   if (MaxBytesToEmit == 0)
 378     MaxBytesToEmit = ByteAlignment;
 379   new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
 380                       getCurrentSectionData());
 381
 382   // Update the maximum alignment on the current section if necessary.
 383   if (ByteAlignment > getCurrentSectionData()->getAlignment())
 384     getCurrentSectionData()->setAlignment(ByteAlignment);
 385 }
 386
 387 void WinCOFFStreamer::EmitCodeAlignment(unsigned ByteAlignment,
 388                                         unsigned MaxBytesToEmit) {
 389   // TODO: This is copied exactly from the MachOStreamer. Consider merging into
 390   // MCObjectStreamer?
 391   if (MaxBytesToEmit == 0)
 392     MaxBytesToEmit = ByteAlignment;
 393   MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
 394                                            getCurrentSectionData());
 395   F->setEmitNops(true);
 396
 397   // Update the maximum alignment on the current section if necessary.
 398   if (ByteAlignment > getCurrentSectionData()->getAlignment())
 399     getCurrentSectionData()->setAlignment(ByteAlignment);
 400 }
 401
 402 void WinCOFFStreamer::EmitValueToOffset(const MCExpr *Offset,
 403                                         unsigned char Value) {
 404   llvm_unreachable("not implemented");
 405 }
 406
 407 void WinCOFFStreamer::EmitFileDirective(StringRef Filename) {
 408   // Ignore for now, linkers don't care, and proper debug
 409   // info will be a much large effort.
 410 }
 411
 412 void WinCOFFStreamer::EmitDwarfFileDirective(unsigned FileNo,
 413                                              StringRef Filename) {
 414   llvm_unreachable("not implemented");
 415 }
 416
 417 void WinCOFFStreamer::EmitInstruction(const MCInst &Instruction) {
 418   for (unsigned i = 0, e = Instruction.getNumOperands(); i != e; ++i)
 419     if (Instruction.getOperand(i).isExpr())
 420       AddValueSymbols(Instruction.getOperand(i).getExpr());
 421
 422   getCurrentSectionData()->setHasInstructions(true);
 423
 424   MCInstFragment *Fragment =
 425     new MCInstFragment(Instruction, getCurrentSectionData());
 426
 427   raw_svector_ostream VecOS(Fragment->getCode());
 428
 429   getAssembler().getEmitter().EncodeInstruction(Instruction, VecOS,
 430                                                 Fragment->getFixups());
 431 }
 432
 433 void WinCOFFStreamer::Finish() {
 434   MCObjectStreamer::Finish();
 435 }
 436
 437 namespace llvm
 438 {
 439   MCStreamer *createWinCOFFStreamer(MCContext &Context,
 440                                     TargetAsmBackend &TAB,
 441                                     MCCodeEmitter &CE,
 442                                     raw_ostream &OS,
 443                                     bool RelaxAll) {
 444     WinCOFFStreamer *S = new WinCOFFStreamer(Context, TAB, CE, OS);
 445     S->getAssembler().setRelaxAll(RelaxAll);
 446     return S;
 447   }
 448 }