WinCOFFStreamer.cpp revision 218893 
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 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
79private:
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
123WinCOFFStreamer::WinCOFFStreamer(MCContext &Context,
124                                 TargetAsmBackend &TAB,
125                                 MCCodeEmitter &CE,
126                                 raw_ostream &OS)
127    : MCObjectStreamer(Context, TAB, OS, &CE)
128    , CurSymbol(NULL) {
129}
130
131void 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
168void WinCOFFStreamer::InitSections() {
169  SetSectionText();
170  SetSectionData();
171  SetSectionBSS();
172  SetSectionText();
173}
174
175void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
176  assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
177  MCObjectStreamer::EmitLabel(Symbol);
178}
179
180void WinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
181  llvm_unreachable("not implemented");
182}
183
184void WinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
185  llvm_unreachable("not implemented");
186}
187
188void 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
230void 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
255void WinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
256  llvm_unreachable("not implemented");
257}
258
259void 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
268void 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
278void 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
288void WinCOFFStreamer::EndCOFFSymbolDef() {
289  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
290  CurSymbol = NULL;
291}
292
293void WinCOFFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
294  llvm_unreachable("not implemented");
295}
296
297void 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
305void 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
312void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
313                                   unsigned Size,unsigned ByteAlignment) {
314  llvm_unreachable("not implemented");
315}
316
317void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
318                                     uint64_t Size, unsigned ByteAlignment) {
319  llvm_unreachable("not implemented");
320}
321
322void 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
328void 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
344void 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
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::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
380void WinCOFFStreamer::Finish() {
381  MCObjectStreamer::Finish();
382}
383
384namespace 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}
396