WinCOFFStreamer.cpp revision cdf67d5791d044a5f217114e18eb8d6242222b98 
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/MCStreamer.h"
17#include "llvm/MC/MCAsmBackend.h"
18#include "llvm/MC/MCAsmLayout.h"
19#include "llvm/MC/MCAssembler.h"
20#include "llvm/MC/MCCodeEmitter.h"
21#include "llvm/MC/MCContext.h"
22#include "llvm/MC/MCExpr.h"
23#include "llvm/MC/MCObjectStreamer.h"
24#include "llvm/MC/MCSection.h"
25#include "llvm/MC/MCSectionCOFF.h"
26#include "llvm/MC/MCSymbol.h"
27#include "llvm/MC/MCValue.h"
28#include "llvm/MC/MCWin64EH.h"
29#include "llvm/Support/COFF.h"
30#include "llvm/Support/Debug.h"
31#include "llvm/Support/ErrorHandling.h"
32#include "llvm/Support/TargetRegistry.h"
33#include "llvm/Support/raw_ostream.h"
34
35using namespace llvm;
36
37namespace {
38class WinCOFFStreamer : public MCObjectStreamer {
39public:
40  MCSymbol const *CurSymbol;
41
42  WinCOFFStreamer(MCContext &Context,
43                  MCAsmBackend &MAB,
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 InitToTextSection();
54  virtual void EmitLabel(MCSymbol *Symbol);
55  virtual void EmitDebugLabel(MCSymbol *Symbol);
56  virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
57  virtual void EmitThumbFunc(MCSymbol *Func);
58  virtual bool EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
59  virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
60  virtual void BeginCOFFSymbolDef(MCSymbol const *Symbol);
61  virtual void EmitCOFFSymbolStorageClass(int StorageClass);
62  virtual void EmitCOFFSymbolType(int Type);
63  virtual void EndCOFFSymbolDef();
64  virtual void EmitCOFFSecRel32(MCSymbol const *Symbol);
65  virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value);
66  virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
67                                unsigned ByteAlignment);
68  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
69                                     unsigned ByteAlignment);
70  virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
71                            uint64_t Size,unsigned ByteAlignment);
72  virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
73                              uint64_t Size, unsigned ByteAlignment);
74  virtual void EmitFileDirective(StringRef Filename);
75  virtual void EmitIdent(StringRef IdentString);
76  virtual void EmitWin64EHHandlerData();
77  virtual void FinishImpl();
78
79private:
80  virtual void EmitInstToData(const MCInst &Inst) {
81    MCDataFragment *DF = getOrCreateDataFragment();
82
83    SmallVector<MCFixup, 4> Fixups;
84    SmallString<256> Code;
85    raw_svector_ostream VecOS(Code);
86    getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
87    VecOS.flush();
88
89    // Add the fixups and data.
90    for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
91      Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
92      DF->getFixups().push_back(Fixups[i]);
93    }
94    DF->getContents().append(Code.begin(), Code.end());
95  }
96
97  void SetSection(StringRef Section,
98                  unsigned Characteristics,
99                  SectionKind Kind) {
100    SwitchSection(getContext().getCOFFSection(Section, Characteristics, Kind));
101  }
102
103  void SetSectionText() {
104    SetSection(".text",
105               COFF::IMAGE_SCN_CNT_CODE
106             | COFF::IMAGE_SCN_MEM_EXECUTE
107             | COFF::IMAGE_SCN_MEM_READ,
108               SectionKind::getText());
109    EmitCodeAlignment(4, 0);
110  }
111
112  void SetSectionData() {
113    SetSection(".data",
114               COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
115             | COFF::IMAGE_SCN_MEM_READ
116             | COFF::IMAGE_SCN_MEM_WRITE,
117               SectionKind::getDataRel());
118    EmitCodeAlignment(4, 0);
119  }
120
121  void SetSectionBSS() {
122    SetSection(".bss",
123               COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA
124             | COFF::IMAGE_SCN_MEM_READ
125             | COFF::IMAGE_SCN_MEM_WRITE,
126               SectionKind::getBSS());
127    EmitCodeAlignment(4, 0);
128  }
129};
130} // end anonymous namespace.
131
132WinCOFFStreamer::WinCOFFStreamer(MCContext &Context, MCAsmBackend &MAB,
133                                 MCCodeEmitter &CE, raw_ostream &OS)
134    : MCObjectStreamer(Context, 0, MAB, OS, &CE), CurSymbol(NULL) {}
135
136void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
137                                      unsigned ByteAlignment, bool External) {
138  assert(!Symbol->isInSection() && "Symbol must not already have a section!");
139
140  std::string SectionName(".bss$linkonce");
141  SectionName.append(Symbol->getName().begin(), Symbol->getName().end());
142
143  MCSymbolData &SymbolData = getAssembler().getOrCreateSymbolData(*Symbol);
144
145  unsigned Characteristics =
146    COFF::IMAGE_SCN_LNK_COMDAT |
147    COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
148    COFF::IMAGE_SCN_MEM_READ |
149    COFF::IMAGE_SCN_MEM_WRITE;
150
151  int Selection = COFF::IMAGE_COMDAT_SELECT_LARGEST;
152
153  const MCSection *Section = MCStreamer::getContext().getCOFFSection(
154      SectionName, Characteristics, SectionKind::getBSS(), Symbol->getName(),
155      Selection);
156
157  MCSectionData &SectionData = getAssembler().getOrCreateSectionData(*Section);
158
159  if (SectionData.getAlignment() < ByteAlignment)
160    SectionData.setAlignment(ByteAlignment);
161
162  SymbolData.setExternal(External);
163
164  AssignSection(Symbol, Section);
165
166  if (ByteAlignment != 1)
167      new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectionData);
168
169  SymbolData.setFragment(new MCFillFragment(0, 0, Size, &SectionData));
170}
171
172// MCStreamer interface
173
174void WinCOFFStreamer::InitToTextSection() {
175  SetSectionText();
176}
177
178void WinCOFFStreamer::InitSections() {
179  SetSectionText();
180  SetSectionData();
181  SetSectionBSS();
182  SetSectionText();
183}
184
185void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
186  assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
187  MCObjectStreamer::EmitLabel(Symbol);
188}
189
190void WinCOFFStreamer::EmitDebugLabel(MCSymbol *Symbol) {
191  EmitLabel(Symbol);
192}
193void WinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
194  llvm_unreachable("not implemented");
195}
196
197void WinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
198  llvm_unreachable("not implemented");
199}
200
201bool 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  case MCSA_Weak: {
210      MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
211      SD.modifyFlags(COFF::SF_WeakExternal, COFF::SF_WeakExternal);
212      SD.setExternal(true);
213    }
214    break;
215
216  case MCSA_Global:
217    getAssembler().getOrCreateSymbolData(*Symbol).setExternal(true);
218    break;
219
220  default:
221    return false;
222  }
223
224  return true;
225}
226
227void WinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
228  llvm_unreachable("not implemented");
229}
230
231void WinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) {
232  assert((Symbol->isInSection()
233         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
234         : true) && "Got non COFF section in the COFF backend!");
235  assert(CurSymbol == NULL && "EndCOFFSymbolDef must be called between calls "
236                              "to BeginCOFFSymbolDef!");
237  CurSymbol = Symbol;
238}
239
240void WinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
241  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
242  assert((StorageClass & ~0xFF) == 0 && "StorageClass must only have data in "
243                                        "the first byte!");
244
245  getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
246    StorageClass << COFF::SF_ClassShift,
247    COFF::SF_ClassMask);
248}
249
250void WinCOFFStreamer::EmitCOFFSymbolType(int Type) {
251  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
252  assert((Type & ~0xFFFF) == 0 && "Type must only have data in the first 2 "
253                                  "bytes");
254
255  getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
256    Type << COFF::SF_TypeShift,
257    COFF::SF_TypeMask);
258}
259
260void WinCOFFStreamer::EndCOFFSymbolDef() {
261  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
262  CurSymbol = NULL;
263}
264
265void WinCOFFStreamer::EmitCOFFSecRel32(MCSymbol const *Symbol)
266{
267  MCDataFragment *DF = getOrCreateDataFragment();
268
269  DF->getFixups().push_back(
270      MCFixup::Create(DF->getContents().size(),
271                      MCSymbolRefExpr::Create (Symbol, getContext ()),
272                      FK_SecRel_4));
273  DF->getContents().resize(DF->getContents().size() + 4, 0);
274}
275
276void WinCOFFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
277  llvm_unreachable("not implemented");
278}
279
280void WinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
281                                       unsigned ByteAlignment) {
282  assert((Symbol->isInSection()
283         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
284         : true) && "Got non COFF section in the COFF backend!");
285  AddCommonSymbol(Symbol, Size, ByteAlignment, true);
286}
287
288void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
289                                            unsigned ByteAlignment) {
290  assert((Symbol->isInSection()
291         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
292         : true) && "Got non COFF section in the COFF backend!");
293  AddCommonSymbol(Symbol, Size, ByteAlignment, false);
294}
295
296void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
297                                   uint64_t Size,unsigned ByteAlignment) {
298  llvm_unreachable("not implemented");
299}
300
301void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
302                                     uint64_t Size, unsigned ByteAlignment) {
303  llvm_unreachable("not implemented");
304}
305
306void WinCOFFStreamer::EmitFileDirective(StringRef Filename) {
307  // Ignore for now, linkers don't care, and proper debug
308  // info will be a much large effort.
309}
310
311// TODO: Implement this if you want to emit .comment section in COFF obj files.
312void WinCOFFStreamer::EmitIdent(StringRef IdentString) {
313  llvm_unreachable("unsupported directive");
314}
315
316void WinCOFFStreamer::EmitWin64EHHandlerData() {
317  MCStreamer::EmitWin64EHHandlerData();
318
319  // We have to emit the unwind info now, because this directive
320  // actually switches to the .xdata section!
321  MCWin64EHUnwindEmitter::EmitUnwindInfo(*this, getCurrentW64UnwindInfo());
322}
323
324void WinCOFFStreamer::FinishImpl() {
325  EmitFrames(NULL, true);
326  EmitW64Tables();
327  MCObjectStreamer::FinishImpl();
328}
329
330namespace llvm
331{
332  MCStreamer *createWinCOFFStreamer(MCContext &Context,
333                                    MCAsmBackend &MAB,
334                                    MCCodeEmitter &CE,
335                                    raw_ostream &OS,
336                                    bool RelaxAll) {
337    WinCOFFStreamer *S = new WinCOFFStreamer(Context, MAB, CE, OS);
338    S->getAssembler().setRelaxAll(RelaxAll);
339    return S;
340  }
341}
342