WinCOFFStreamer.cpp revision 86c3647ddfa8c39ed5d9eba9f2547544270c7bde 
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  // FIXME: This is all very ugly and depressing. What needs to happen here
161  // depends on quite a few things that are all part of relaxation, which we
162  // don't really even do.
163
164  if (Value->getKind() != MCExpr::SymbolRef) {
165    // TODO: This is exactly the same as MachOStreamer. Consider merging into
166    // MCObjectStreamer.
167    getAssembler().getOrCreateSymbolData(*Symbol);
168    AddValueSymbols(Value);
169    Symbol->setVariableValue(Value);
170  } else {
171    // FIXME: This is a horrible way to do this :(. This should really be
172    // handled after we are done with the MC* objects and immediately before
173    // writing out the object file when we know exactly what the symbol should
174    // look like in the coff symbol table. I'm not doing that now because the
175    // COFF object writer doesn't have a clearly defined separation between MC
176    // data structures, the object writers data structures, and the raw, POD,
177    // data structures that get written to disk.
178
179    // Copy over the aliased data.
180    MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
181    const MCSymbolData &RealSD = getAssembler().getOrCreateSymbolData(
182      dyn_cast<const MCSymbolRefExpr>(Value)->getSymbol());
183
184    // FIXME: This is particularly nasty because it breaks as soon as any data
185    // members of MCSymbolData change.
186    SD.CommonAlign     = RealSD.CommonAlign;
187    SD.CommonSize      = RealSD.CommonSize;
188    SD.Flags           = RealSD.Flags;
189    SD.Fragment        = RealSD.Fragment;
190    SD.Index           = RealSD.Index;
191    SD.IsExternal      = RealSD.IsExternal;
192    SD.IsPrivateExtern = RealSD.IsPrivateExtern;
193    SD.Offset          = RealSD.Offset;
194    SD.SymbolSize      = RealSD.SymbolSize;
195  }
196}
197
198void WinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
199                                          MCSymbolAttr Attribute) {
200  switch (Attribute) {
201  case MCSA_WeakReference:
202    getAssembler().getOrCreateSymbolData(*Symbol).modifyFlags(
203      COFF::SF_WeakReference,
204      COFF::SF_WeakReference);
205    break;
206
207  case MCSA_Global:
208    getAssembler().getOrCreateSymbolData(*Symbol).setExternal(true);
209    break;
210
211  default:
212    llvm_unreachable("unsupported attribute");
213    break;
214  }
215}
216
217void WinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
218  llvm_unreachable("not implemented");
219}
220
221void WinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) {
222  assert(CurSymbol == NULL && "EndCOFFSymbolDef must be called between calls "
223                              "to BeginCOFFSymbolDef!");
224  CurSymbol = Symbol;
225}
226
227void WinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
228  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
229  assert((StorageClass & ~0xFF) == 0 && "StorageClass must only have data in "
230                                        "the first byte!");
231
232  getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
233    StorageClass << COFF::SF_ClassShift,
234    COFF::SF_ClassMask);
235}
236
237void WinCOFFStreamer::EmitCOFFSymbolType(int Type) {
238  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
239  assert((Type & ~0xFFFF) == 0 && "Type must only have data in the first 2 "
240                                  "bytes");
241
242  getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
243    Type << COFF::SF_TypeShift,
244    COFF::SF_TypeMask);
245}
246
247void WinCOFFStreamer::EndCOFFSymbolDef() {
248  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
249  CurSymbol = NULL;
250}
251
252void WinCOFFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
253  llvm_unreachable("not implemented");
254}
255
256void WinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
257                                       unsigned ByteAlignment) {
258  AddCommonSymbol(Symbol, Size, ByteAlignment, true);
259}
260
261void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
262  AddCommonSymbol(Symbol, Size, 1, false);
263}
264
265void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
266                                   unsigned Size,unsigned ByteAlignment) {
267  llvm_unreachable("not implemented");
268}
269
270void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
271                                     uint64_t Size, unsigned ByteAlignment) {
272  llvm_unreachable("not implemented");
273}
274
275void WinCOFFStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
276  // TODO: This is copied exactly from the MachOStreamer. Consider merging into
277  // MCObjectStreamer?
278  getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
279}
280
281void WinCOFFStreamer::EmitValue(const MCExpr *Value, unsigned Size,
282                                unsigned AddrSpace) {
283  assert(AddrSpace == 0 && "Address space must be 0!");
284
285  // TODO: This is copied exactly from the MachOStreamer. Consider merging into
286  // MCObjectStreamer?
287  MCDataFragment *DF = getOrCreateDataFragment();
288
289  // Avoid fixups when possible.
290  int64_t AbsValue;
291  if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
292    // FIXME: Endianness assumption.
293    for (unsigned i = 0; i != Size; ++i)
294      DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
295  } else {
296    DF->addFixup(MCFixup::Create(DF->getContents().size(),
297                                 AddValueSymbols(Value),
298                                 MCFixup::getKindForSize(Size)));
299    DF->getContents().resize(DF->getContents().size() + Size, 0);
300  }
301}
302
303void WinCOFFStreamer::EmitGPRel32Value(const MCExpr *Value) {
304  llvm_unreachable("not implemented");
305}
306
307void WinCOFFStreamer::EmitValueToAlignment(unsigned ByteAlignment,
308                                           int64_t Value,
309                                           unsigned ValueSize,
310                                           unsigned MaxBytesToEmit) {
311  // TODO: This is copied exactly from the MachOStreamer. Consider merging into
312  // MCObjectStreamer?
313  if (MaxBytesToEmit == 0)
314    MaxBytesToEmit = ByteAlignment;
315  new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
316                      getCurrentSectionData());
317
318  // Update the maximum alignment on the current section if necessary.
319  if (ByteAlignment > getCurrentSectionData()->getAlignment())
320    getCurrentSectionData()->setAlignment(ByteAlignment);
321}
322
323void WinCOFFStreamer::EmitCodeAlignment(unsigned ByteAlignment,
324                                        unsigned MaxBytesToEmit) {
325  // TODO: This is copied exactly from the MachOStreamer. Consider merging into
326  // MCObjectStreamer?
327  if (MaxBytesToEmit == 0)
328    MaxBytesToEmit = ByteAlignment;
329  MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
330                                           getCurrentSectionData());
331  F->setEmitNops(true);
332
333  // Update the maximum alignment on the current section if necessary.
334  if (ByteAlignment > getCurrentSectionData()->getAlignment())
335    getCurrentSectionData()->setAlignment(ByteAlignment);
336}
337
338void WinCOFFStreamer::EmitValueToOffset(const MCExpr *Offset,
339                                        unsigned char Value) {
340  llvm_unreachable("not implemented");
341}
342
343void WinCOFFStreamer::EmitFileDirective(StringRef Filename) {
344  // Ignore for now, linkers don't care, and proper debug
345  // info will be a much large effort.
346}
347
348void WinCOFFStreamer::EmitDwarfFileDirective(unsigned FileNo,
349                                             StringRef Filename) {
350  llvm_unreachable("not implemented");
351}
352
353void WinCOFFStreamer::EmitInstruction(const MCInst &Instruction) {
354  for (unsigned i = 0, e = Instruction.getNumOperands(); i != e; ++i)
355    if (Instruction.getOperand(i).isExpr())
356      AddValueSymbols(Instruction.getOperand(i).getExpr());
357
358  getCurrentSectionData()->setHasInstructions(true);
359
360  MCInstFragment *Fragment =
361    new MCInstFragment(Instruction, getCurrentSectionData());
362
363  raw_svector_ostream VecOS(Fragment->getCode());
364
365  getAssembler().getEmitter().EncodeInstruction(Instruction, VecOS,
366                                                Fragment->getFixups());
367}
368
369void WinCOFFStreamer::Finish() {
370  MCObjectStreamer::Finish();
371}
372
373namespace llvm
374{
375  MCStreamer *createWinCOFFStreamer(MCContext &Context,
376                                    TargetAsmBackend &TAB,
377                                    MCCodeEmitter &CE,
378                                    raw_ostream &OS,
379                                    bool RelaxAll) {
380    WinCOFFStreamer *S = new WinCOFFStreamer(Context, TAB, CE, OS);
381    S->getAssembler().setRelaxAll(RelaxAll);
382    return S;
383  }
384}
385