WinCOFFStreamer.cpp revision d47f4a9c982d264e46a6a2fe0f357288768bb5b9 
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"
34using namespace llvm;
35
36namespace {
37class WinCOFFStreamer : public MCObjectStreamer {
38public:
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} // end anonymous namespace.
84
85WinCOFFStreamer::WinCOFFStreamer(MCContext &Context,
86                                 TargetAsmBackend &TAB,
87                                 MCCodeEmitter &CE,
88                                 raw_ostream &OS)
89    : MCObjectStreamer(Context, TAB, OS, &CE, true)
90    , CurSymbol(NULL) {
91}
92
93void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
94                                      unsigned ByteAlignment, bool External) {
95  assert(!Symbol->isInSection() && "Symbol must not already have a section!");
96
97  std::string SectionName(".bss$linkonce");
98  SectionName.append(Symbol->getName().begin(), Symbol->getName().end());
99
100  MCSymbolData &SymbolData = getAssembler().getOrCreateSymbolData(*Symbol);
101
102  unsigned Characteristics =
103    COFF::IMAGE_SCN_LNK_COMDAT |
104    COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
105    COFF::IMAGE_SCN_MEM_READ |
106    COFF::IMAGE_SCN_MEM_WRITE;
107
108  int Selection = COFF::IMAGE_COMDAT_SELECT_LARGEST;
109
110  const MCSection *Section = MCStreamer::getContext().getCOFFSection(
111    SectionName, Characteristics, Selection, SectionKind::getBSS());
112
113  MCSectionData &SectionData = getAssembler().getOrCreateSectionData(*Section);
114
115  if (SectionData.getAlignment() < ByteAlignment)
116    SectionData.setAlignment(ByteAlignment);
117
118  SymbolData.setExternal(External);
119
120  Symbol->setSection(*Section);
121
122  if (ByteAlignment != 1)
123      new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectionData);
124
125  SymbolData.setFragment(new MCFillFragment(0, 0, Size, &SectionData));
126}
127
128// MCStreamer interface
129
130void WinCOFFStreamer::InitSections() {
131}
132
133void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
134  // TODO: This is copied almost exactly from the MachOStreamer. Consider
135  // merging into MCObjectStreamer?
136  assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
137  assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
138  assert(CurSection && "Cannot emit before setting section!");
139
140  Symbol->setSection(*CurSection);
141
142  MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
143
144  // FIXME: This is wasteful, we don't necessarily need to create a data
145  // fragment. Instead, we should mark the symbol as pointing into the data
146  // fragment if it exists, otherwise we should just queue the label and set its
147  // fragment pointer when we emit the next fragment.
148  MCDataFragment *DF = getOrCreateDataFragment();
149
150  assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
151  SD.setFragment(DF);
152  SD.setOffset(DF->getContents().size());
153}
154
155void WinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
156  llvm_unreachable("not implemented");
157}
158
159void WinCOFFStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
160  assert((Symbol->isInSection()
161         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
162         : true) && "Got non COFF section in the COFF backend!");
163  // FIXME: This is all very ugly and depressing. What needs to happen here
164  // depends on quite a few things that are all part of relaxation, which we
165  // don't really even do.
166
167  if (Value->getKind() != MCExpr::SymbolRef) {
168    // TODO: This is exactly the same as MachOStreamer. Consider merging into
169    // MCObjectStreamer.
170    getAssembler().getOrCreateSymbolData(*Symbol);
171    AddValueSymbols(Value);
172    Symbol->setVariableValue(Value);
173  } else {
174    // FIXME: This is a horrible way to do this :(. This should really be
175    // handled after we are done with the MC* objects and immediately before
176    // writing out the object file when we know exactly what the symbol should
177    // look like in the coff symbol table. I'm not doing that now because the
178    // COFF object writer doesn't have a clearly defined separation between MC
179    // data structures, the object writers data structures, and the raw, POD,
180    // data structures that get written to disk.
181
182    // Copy over the aliased data.
183    MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
184    const MCSymbolData &RealSD = getAssembler().getOrCreateSymbolData(
185      dyn_cast<const MCSymbolRefExpr>(Value)->getSymbol());
186
187    // FIXME: This is particularly nasty because it breaks as soon as any data
188    // members of MCSymbolData change.
189    SD.CommonAlign     = RealSD.CommonAlign;
190    SD.CommonSize      = RealSD.CommonSize;
191    SD.Flags           = RealSD.Flags;
192    SD.Fragment        = RealSD.Fragment;
193    SD.Index           = RealSD.Index;
194    SD.IsExternal      = RealSD.IsExternal;
195    SD.IsPrivateExtern = RealSD.IsPrivateExtern;
196    SD.Offset          = RealSD.Offset;
197    SD.SymbolSize      = RealSD.SymbolSize;
198  }
199}
200
201void WinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
202                                          MCSymbolAttr Attribute) {
203  assert(Symbol && "Symbol must be non-null!");
204  assert((Symbol->isInSection()
205         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
206         : true) && "Got non COFF section in the COFF backend!");
207  switch (Attribute) {
208  case MCSA_WeakReference:
209    getAssembler().getOrCreateSymbolData(*Symbol).modifyFlags(
210      COFF::SF_WeakReference,
211      COFF::SF_WeakReference);
212    break;
213
214  case MCSA_Global:
215    getAssembler().getOrCreateSymbolData(*Symbol).setExternal(true);
216    break;
217
218  default:
219    llvm_unreachable("unsupported attribute");
220    break;
221  }
222}
223
224void WinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
225  llvm_unreachable("not implemented");
226}
227
228void WinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) {
229  assert((Symbol->isInSection()
230         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
231         : true) && "Got non COFF section in the COFF backend!");
232  assert(CurSymbol == NULL && "EndCOFFSymbolDef must be called between calls "
233                              "to BeginCOFFSymbolDef!");
234  CurSymbol = Symbol;
235}
236
237void WinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
238  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
239  assert((StorageClass & ~0xFF) == 0 && "StorageClass must only have data in "
240                                        "the first byte!");
241
242  getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
243    StorageClass << COFF::SF_ClassShift,
244    COFF::SF_ClassMask);
245}
246
247void WinCOFFStreamer::EmitCOFFSymbolType(int Type) {
248  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
249  assert((Type & ~0xFFFF) == 0 && "Type must only have data in the first 2 "
250                                  "bytes");
251
252  getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
253    Type << COFF::SF_TypeShift,
254    COFF::SF_TypeMask);
255}
256
257void WinCOFFStreamer::EndCOFFSymbolDef() {
258  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
259  CurSymbol = NULL;
260}
261
262void WinCOFFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
263  llvm_unreachable("not implemented");
264}
265
266void WinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
267                                       unsigned ByteAlignment) {
268  assert((Symbol->isInSection()
269         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
270         : true) && "Got non COFF section in the COFF backend!");
271  AddCommonSymbol(Symbol, Size, ByteAlignment, true);
272}
273
274void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
275  assert((Symbol->isInSection()
276         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
277         : true) && "Got non COFF section in the COFF backend!");
278  AddCommonSymbol(Symbol, Size, 1, false);
279}
280
281void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
282                                   unsigned Size,unsigned ByteAlignment) {
283  llvm_unreachable("not implemented");
284}
285
286void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
287                                     uint64_t Size, unsigned ByteAlignment) {
288  llvm_unreachable("not implemented");
289}
290
291void WinCOFFStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
292  // TODO: This is copied exactly from the MachOStreamer. Consider merging into
293  // MCObjectStreamer?
294  getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
295}
296
297void WinCOFFStreamer::EmitValue(const MCExpr *Value, unsigned Size,
298                                unsigned AddrSpace) {
299  assert(AddrSpace == 0 && "Address space must be 0!");
300
301  // TODO: This is copied exactly from the MachOStreamer. Consider merging into
302  // MCObjectStreamer?
303  MCDataFragment *DF = getOrCreateDataFragment();
304
305  // Avoid fixups when possible.
306  int64_t AbsValue;
307  if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
308    // FIXME: Endianness assumption.
309    for (unsigned i = 0; i != Size; ++i)
310      DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
311  } else {
312    DF->addFixup(MCFixup::Create(DF->getContents().size(),
313                                 AddValueSymbols(Value),
314                                 MCFixup::getKindForSize(Size)));
315    DF->getContents().resize(DF->getContents().size() + Size, 0);
316  }
317}
318
319void WinCOFFStreamer::EmitGPRel32Value(const MCExpr *Value) {
320  llvm_unreachable("not implemented");
321}
322
323void WinCOFFStreamer::EmitValueToAlignment(unsigned ByteAlignment,
324                                           int64_t Value,
325                                           unsigned ValueSize,
326                                           unsigned MaxBytesToEmit) {
327  // TODO: This is copied exactly from the MachOStreamer. Consider merging into
328  // MCObjectStreamer?
329  if (MaxBytesToEmit == 0)
330    MaxBytesToEmit = ByteAlignment;
331  new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
332                      getCurrentSectionData());
333
334  // Update the maximum alignment on the current section if necessary.
335  if (ByteAlignment > getCurrentSectionData()->getAlignment())
336    getCurrentSectionData()->setAlignment(ByteAlignment);
337}
338
339void WinCOFFStreamer::EmitCodeAlignment(unsigned ByteAlignment,
340                                        unsigned MaxBytesToEmit) {
341  // TODO: This is copied exactly from the MachOStreamer. Consider merging into
342  // MCObjectStreamer?
343  if (MaxBytesToEmit == 0)
344    MaxBytesToEmit = ByteAlignment;
345  MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
346                                           getCurrentSectionData());
347  F->setEmitNops(true);
348
349  // Update the maximum alignment on the current section if necessary.
350  if (ByteAlignment > getCurrentSectionData()->getAlignment())
351    getCurrentSectionData()->setAlignment(ByteAlignment);
352}
353
354void WinCOFFStreamer::EmitValueToOffset(const MCExpr *Offset,
355                                        unsigned char Value) {
356  llvm_unreachable("not implemented");
357}
358
359void 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
364void WinCOFFStreamer::EmitDwarfFileDirective(unsigned FileNo,
365                                             StringRef Filename) {
366  llvm_unreachable("not implemented");
367}
368
369void WinCOFFStreamer::EmitInstruction(const MCInst &Instruction) {
370  for (unsigned i = 0, e = Instruction.getNumOperands(); i != e; ++i)
371    if (Instruction.getOperand(i).isExpr())
372      AddValueSymbols(Instruction.getOperand(i).getExpr());
373
374  getCurrentSectionData()->setHasInstructions(true);
375
376  MCInstFragment *Fragment =
377    new MCInstFragment(Instruction, getCurrentSectionData());
378
379  raw_svector_ostream VecOS(Fragment->getCode());
380
381  getAssembler().getEmitter().EncodeInstruction(Instruction, VecOS,
382                                                Fragment->getFixups());
383}
384
385void WinCOFFStreamer::Finish() {
386  MCObjectStreamer::Finish();
387}
388
389namespace llvm
390{
391  MCStreamer *createWinCOFFStreamer(MCContext &Context,
392                                    TargetAsmBackend &TAB,
393                                    MCCodeEmitter &CE,
394                                    raw_ostream &OS,
395                                    bool RelaxAll) {
396    WinCOFFStreamer *S = new WinCOFFStreamer(Context, TAB, CE, OS);
397    S->getAssembler().setRelaxAll(RelaxAll);
398    return S;
399  }
400}
401