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