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/MC/MCWin64EH.h"
  27 #include "llvm/Target/TargetRegistry.h"
  28 #include "llvm/Target/TargetAsmBackend.h"
  29 #include "llvm/ADT/StringMap.h"
  30
  31 #include "llvm/Support/COFF.h"
  32 #include "llvm/Support/Debug.h"
  33 #include "llvm/Support/ErrorHandling.h"
  34 #include "llvm/Support/raw_ostream.h"
  35 using namespace llvm;
  36
  37 namespace {
  38 class WinCOFFStreamer : public MCObjectStreamer {
  39 public:
  40   MCSymbol const *CurSymbol;
  41
  42   WinCOFFStreamer(MCContext &Context,
  43                   TargetAsmBackend &TAB,
  44                   MCCodeEmitter &CE,
  45                   raw_ostream &OS);
  46
  47   void AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
  48                        unsigned ByteAlignment, bool External);
  49
  50   // MCStreamer interface
  51
  52   virtual void InitSections();
  53   virtual void EmitLabel(MCSymbol *Symbol);
  54   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
  55   virtual void EmitThumbFunc(MCSymbol *Func);
  56   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
  57   virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
  58   virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
  59   virtual void BeginCOFFSymbolDef(MCSymbol const *Symbol);
  60   virtual void EmitCOFFSymbolStorageClass(int StorageClass);
  61   virtual void EmitCOFFSymbolType(int Type);
  62   virtual void EndCOFFSymbolDef();
  63   virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value);
  64   virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
  65                                 unsigned ByteAlignment);
  66   virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size);
  67   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
  68                             unsigned Size,unsigned ByteAlignment);
  69   virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
  70                               uint64_t Size, unsigned ByteAlignment);
  71   virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
  72   virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
  73                                    unsigned ValueSize, unsigned MaxBytesToEmit);
  74   virtual void EmitCodeAlignment(unsigned ByteAlignment,
  75                                  unsigned MaxBytesToEmit);
  76   virtual void EmitFileDirective(StringRef Filename);
  77   virtual void EmitInstruction(const MCInst &Instruction);
  78   virtual void EmitWin64EHHandlerData();
  79   virtual void Finish();
  80
  81 private:
  82   virtual void EmitInstToFragment(const MCInst &Inst) {
  83     llvm_unreachable("Not used by WinCOFF.");
  84   }
  85   virtual void EmitInstToData(const MCInst &Inst) {
  86     llvm_unreachable("Not used by WinCOFF.");
  87   }
  88
  89   void SetSection(StringRef Section,
  90                   unsigned Characteristics,
  91                   SectionKind Kind) {
  92     SwitchSection(getContext().getCOFFSection(Section, Characteristics, Kind));
  93   }
  94
  95   void SetSectionText() {
  96     SetSection(".text",
  97                COFF::IMAGE_SCN_CNT_CODE
  98              | COFF::IMAGE_SCN_MEM_EXECUTE
  99              | COFF::IMAGE_SCN_MEM_READ,
 100                SectionKind::getText());
 101     EmitCodeAlignment(4, 0);
 102   }
 103
 104   void SetSectionData() {
 105     SetSection(".data",
 106                COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
 107              | COFF::IMAGE_SCN_MEM_READ
 108              | COFF::IMAGE_SCN_MEM_WRITE,
 109                SectionKind::getDataRel());
 110     EmitCodeAlignment(4, 0);
 111   }
 112
 113   void SetSectionBSS() {
 114     SetSection(".bss",
 115                COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA
 116              | COFF::IMAGE_SCN_MEM_READ
 117              | COFF::IMAGE_SCN_MEM_WRITE,
 118                SectionKind::getBSS());
 119     EmitCodeAlignment(4, 0);
 120   }
 121
 122 };
 123 } // end anonymous namespace.
 124
 125 WinCOFFStreamer::WinCOFFStreamer(MCContext &Context,
 126                                  TargetAsmBackend &TAB,
 127                                  MCCodeEmitter &CE,
 128                                  raw_ostream &OS)
 129     : MCObjectStreamer(Context, TAB, OS, &CE)
 130     , CurSymbol(NULL) {
 131 }
 132
 133 void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 134                                       unsigned ByteAlignment, bool External) {
 135   assert(!Symbol->isInSection() && "Symbol must not already have a section!");
 136
 137   std::string SectionName(".bss$linkonce");
 138   SectionName.append(Symbol->getName().begin(), Symbol->getName().end());
 139
 140   MCSymbolData &SymbolData = getAssembler().getOrCreateSymbolData(*Symbol);
 141
 142   unsigned Characteristics =
 143     COFF::IMAGE_SCN_LNK_COMDAT |
 144     COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
 145     COFF::IMAGE_SCN_MEM_READ |
 146     COFF::IMAGE_SCN_MEM_WRITE;
 147
 148   int Selection = COFF::IMAGE_COMDAT_SELECT_LARGEST;
 149
 150   const MCSection *Section = MCStreamer::getContext().getCOFFSection(
 151     SectionName, Characteristics, Selection, SectionKind::getBSS());
 152
 153   MCSectionData &SectionData = getAssembler().getOrCreateSectionData(*Section);
 154
 155   if (SectionData.getAlignment() < ByteAlignment)
 156     SectionData.setAlignment(ByteAlignment);
 157
 158   SymbolData.setExternal(External);
 159
 160   Symbol->setSection(*Section);
 161
 162   if (ByteAlignment != 1)
 163       new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectionData);
 164
 165   SymbolData.setFragment(new MCFillFragment(0, 0, Size, &SectionData));
 166 }
 167
 168 // MCStreamer interface
 169
 170 void WinCOFFStreamer::InitSections() {
 171   SetSectionText();
 172   SetSectionData();
 173   SetSectionBSS();
 174   SetSectionText();
 175 }
 176
 177 void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
 178   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
 179   MCObjectStreamer::EmitLabel(Symbol);
 180 }
 181
 182 void WinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
 183   llvm_unreachable("not implemented");
 184 }
 185
 186 void WinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
 187   llvm_unreachable("not implemented");
 188 }
 189
 190 void WinCOFFStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
 191   assert((Symbol->isInSection()
 192          ? Symbol->getSection().getVariant() == MCSection::SV_COFF
 193          : true) && "Got non COFF section in the COFF backend!");
 194   // FIXME: This is all very ugly and depressing. What needs to happen here
 195   // depends on quite a few things that are all part of relaxation, which we
 196   // don't really even do.
 197
 198   if (Value->getKind() != MCExpr::SymbolRef) {
 199     // TODO: This is exactly the same as MachOStreamer. Consider merging into
 200     // MCObjectStreamer.
 201     getAssembler().getOrCreateSymbolData(*Symbol);
 202     AddValueSymbols(Value);
 203     Symbol->setVariableValue(Value);
 204   } else {
 205     // FIXME: This is a horrible way to do this :(. This should really be
 206     // handled after we are done with the MC* objects and immediately before
 207     // writing out the object file when we know exactly what the symbol should
 208     // look like in the coff symbol table. I'm not doing that now because the
 209     // COFF object writer doesn't have a clearly defined separation between MC
 210     // data structures, the object writers data structures, and the raw, POD,
 211     // data structures that get written to disk.
 212
 213     // Copy over the aliased data.
 214     MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
 215     const MCSymbolData &RealSD = getAssembler().getOrCreateSymbolData(
 216       dyn_cast<const MCSymbolRefExpr>(Value)->getSymbol());
 217
 218     // FIXME: This is particularly nasty because it breaks as soon as any data
 219     // members of MCSymbolData change.
 220     SD.CommonAlign     = RealSD.CommonAlign;
 221     SD.CommonSize      = RealSD.CommonSize;
 222     SD.Flags           = RealSD.Flags;
 223     SD.Fragment        = RealSD.Fragment;
 224     SD.Index           = RealSD.Index;
 225     SD.IsExternal      = RealSD.IsExternal;
 226     SD.IsPrivateExtern = RealSD.IsPrivateExtern;
 227     SD.Offset          = RealSD.Offset;
 228     SD.SymbolSize      = RealSD.SymbolSize;
 229   }
 230 }
 231
 232 void WinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
 233                                           MCSymbolAttr Attribute) {
 234   assert(Symbol && "Symbol must be non-null!");
 235   assert((Symbol->isInSection()
 236          ? Symbol->getSection().getVariant() == MCSection::SV_COFF
 237          : true) && "Got non COFF section in the COFF backend!");
 238   switch (Attribute) {
 239   case MCSA_WeakReference:
 240   case MCSA_Weak: {
 241       MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
 242       SD.modifyFlags(COFF::SF_WeakExternal, COFF::SF_WeakExternal);
 243       SD.setExternal(true);
 244     }
 245     break;
 246
 247   case MCSA_Global:
 248     getAssembler().getOrCreateSymbolData(*Symbol).setExternal(true);
 249     break;
 250
 251   default:
 252     llvm_unreachable("unsupported attribute");
 253     break;
 254   }
 255 }
 256
 257 void WinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
 258   llvm_unreachable("not implemented");
 259 }
 260
 261 void WinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) {
 262   assert((Symbol->isInSection()
 263          ? Symbol->getSection().getVariant() == MCSection::SV_COFF
 264          : true) && "Got non COFF section in the COFF backend!");
 265   assert(CurSymbol == NULL && "EndCOFFSymbolDef must be called between calls "
 266                               "to BeginCOFFSymbolDef!");
 267   CurSymbol = Symbol;
 268 }
 269
 270 void WinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
 271   assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
 272   assert((StorageClass & ~0xFF) == 0 && "StorageClass must only have data in "
 273                                         "the first byte!");
 274
 275   getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
 276     StorageClass << COFF::SF_ClassShift,
 277     COFF::SF_ClassMask);
 278 }
 279
 280 void WinCOFFStreamer::EmitCOFFSymbolType(int Type) {
 281   assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
 282   assert((Type & ~0xFFFF) == 0 && "Type must only have data in the first 2 "
 283                                   "bytes");
 284
 285   getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
 286     Type << COFF::SF_TypeShift,
 287     COFF::SF_TypeMask);
 288 }
 289
 290 void WinCOFFStreamer::EndCOFFSymbolDef() {
 291   assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
 292   CurSymbol = NULL;
 293 }
 294
 295 void WinCOFFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
 296   llvm_unreachable("not implemented");
 297 }
 298
 299 void WinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 300                                        unsigned ByteAlignment) {
 301   assert((Symbol->isInSection()
 302          ? Symbol->getSection().getVariant() == MCSection::SV_COFF
 303          : true) && "Got non COFF section in the COFF backend!");
 304   AddCommonSymbol(Symbol, Size, ByteAlignment, true);
 305 }
 306
 307 void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
 308   assert((Symbol->isInSection()
 309          ? Symbol->getSection().getVariant() == MCSection::SV_COFF
 310          : true) && "Got non COFF section in the COFF backend!");
 311   AddCommonSymbol(Symbol, Size, 1, false);
 312 }
 313
 314 void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
 315                                    unsigned Size,unsigned ByteAlignment) {
 316   llvm_unreachable("not implemented");
 317 }
 318
 319 void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
 320                                      uint64_t Size, unsigned ByteAlignment) {
 321   llvm_unreachable("not implemented");
 322 }
 323
 324 void WinCOFFStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
 325   // TODO: This is copied exactly from the MachOStreamer. Consider merging into
 326   // MCObjectStreamer?
 327   getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
 328 }
 329
 330 void WinCOFFStreamer::EmitValueToAlignment(unsigned ByteAlignment,
 331                                            int64_t Value,
 332                                            unsigned ValueSize,
 333                                            unsigned MaxBytesToEmit) {
 334   // TODO: This is copied exactly from the MachOStreamer. Consider merging into
 335   // MCObjectStreamer?
 336   if (MaxBytesToEmit == 0)
 337     MaxBytesToEmit = ByteAlignment;
 338   new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
 339                       getCurrentSectionData());
 340
 341   // Update the maximum alignment on the current section if necessary.
 342   if (ByteAlignment > getCurrentSectionData()->getAlignment())
 343     getCurrentSectionData()->setAlignment(ByteAlignment);
 344 }
 345
 346 void WinCOFFStreamer::EmitCodeAlignment(unsigned ByteAlignment,
 347                                         unsigned MaxBytesToEmit) {
 348   // TODO: This is copied exactly from the MachOStreamer. Consider merging into
 349   // MCObjectStreamer?
 350   if (MaxBytesToEmit == 0)
 351     MaxBytesToEmit = ByteAlignment;
 352   MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
 353                                            getCurrentSectionData());
 354   F->setEmitNops(true);
 355
 356   // Update the maximum alignment on the current section if necessary.
 357   if (ByteAlignment > getCurrentSectionData()->getAlignment())
 358     getCurrentSectionData()->setAlignment(ByteAlignment);
 359 }
 360
 361 void WinCOFFStreamer::EmitFileDirective(StringRef Filename) {
 362   // Ignore for now, linkers don't care, and proper debug
 363   // info will be a much large effort.
 364 }
 365
 366 void WinCOFFStreamer::EmitInstruction(const MCInst &Instruction) {
 367   for (unsigned i = 0, e = Instruction.getNumOperands(); i != e; ++i)
 368     if (Instruction.getOperand(i).isExpr())
 369       AddValueSymbols(Instruction.getOperand(i).getExpr());
 370
 371   getCurrentSectionData()->setHasInstructions(true);
 372
 373   MCInstFragment *Fragment =
 374     new MCInstFragment(Instruction, getCurrentSectionData());
 375
 376   raw_svector_ostream VecOS(Fragment->getCode());
 377
 378   getAssembler().getEmitter().EncodeInstruction(Instruction, VecOS,
 379                                                 Fragment->getFixups());
 380 }
 381
 382 void WinCOFFStreamer::EmitWin64EHHandlerData() {
 383   MCStreamer::EmitWin64EHHandlerData();
 384
 385   // We have to emit the unwind info now, because this directive
 386   // actually switches to the .xdata section!
 387   MCWin64EHUnwindEmitter::EmitUnwindInfo(*this, getCurrentW64UnwindInfo());
 388 }
 389
 390 void WinCOFFStreamer::Finish() {
 391   EmitW64Tables();
 392   MCObjectStreamer::Finish();
 393 }
 394
 395 namespace llvm
 396 {
 397   MCStreamer *createWinCOFFStreamer(MCContext &Context,
 398                                     TargetAsmBackend &TAB,
 399                                     MCCodeEmitter &CE,
 400                                     raw_ostream &OS,
 401                                     bool RelaxAll) {
 402     WinCOFFStreamer *S = new WinCOFFStreamer(Context, TAB, CE, OS);
 403     S->getAssembler().setRelaxAll(RelaxAll);
 404     return S;
 405   }
 406 }