WinCOFFStreamer.cpp revision ef76b273f96d99a4a260f3dcadde8fbb96256cf3 
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 EmitLabel(MCSymbol *Symbol);
54  virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
55  virtual void EmitThumbFunc(MCSymbol *Func);
56  virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
57  virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
58  virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
59  virtual void BeginCOFFSymbolDef(MCSymbol const *Symbol);
60  virtual void EmitCOFFSymbolStorageClass(int StorageClass);
61  virtual void EmitCOFFSymbolType(int Type);
62  virtual void EndCOFFSymbolDef();
63  virtual void EmitCOFFSecRel32(MCSymbol const *Symbol);
64  virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value);
65  virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
66                                unsigned ByteAlignment);
67  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
68                                     unsigned ByteAlignment);
69  virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
70                            uint64_t Size,unsigned ByteAlignment);
71  virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
72                              uint64_t Size, unsigned ByteAlignment);
73  virtual void EmitFileDirective(StringRef Filename);
74  virtual void EmitInstruction(const MCInst &Instruction);
75  virtual void EmitWin64EHHandlerData();
76  virtual void FinishImpl();
77
78private:
79  virtual void EmitInstToFragment(const MCInst &Inst) {
80    llvm_unreachable("Not used by WinCOFF.");
81  }
82  virtual void EmitInstToData(const MCInst &Inst) {
83    llvm_unreachable("Not used by WinCOFF.");
84  }
85
86  void SetSection(StringRef Section,
87                  unsigned Characteristics,
88                  SectionKind Kind) {
89    SwitchSection(getContext().getCOFFSection(Section, Characteristics, Kind));
90  }
91
92  void SetSectionText() {
93    SetSection(".text",
94               COFF::IMAGE_SCN_CNT_CODE
95             | COFF::IMAGE_SCN_MEM_EXECUTE
96             | COFF::IMAGE_SCN_MEM_READ,
97               SectionKind::getText());
98    EmitCodeAlignment(4, 0);
99  }
100
101  void SetSectionData() {
102    SetSection(".data",
103               COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
104             | COFF::IMAGE_SCN_MEM_READ
105             | COFF::IMAGE_SCN_MEM_WRITE,
106               SectionKind::getDataRel());
107    EmitCodeAlignment(4, 0);
108  }
109
110  void SetSectionBSS() {
111    SetSection(".bss",
112               COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA
113             | COFF::IMAGE_SCN_MEM_READ
114             | COFF::IMAGE_SCN_MEM_WRITE,
115               SectionKind::getBSS());
116    EmitCodeAlignment(4, 0);
117  }
118
119};
120} // end anonymous namespace.
121
122WinCOFFStreamer::WinCOFFStreamer(MCContext &Context,
123                                 MCAsmBackend &MAB,
124                                 MCCodeEmitter &CE,
125                                 raw_ostream &OS)
126    : MCObjectStreamer(Context, MAB, OS, &CE)
127    , CurSymbol(NULL) {
128}
129
130void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
131                                      unsigned ByteAlignment, bool External) {
132  assert(!Symbol->isInSection() && "Symbol must not already have a section!");
133
134  std::string SectionName(".bss$linkonce");
135  SectionName.append(Symbol->getName().begin(), Symbol->getName().end());
136
137  MCSymbolData &SymbolData = getAssembler().getOrCreateSymbolData(*Symbol);
138
139  unsigned Characteristics =
140    COFF::IMAGE_SCN_LNK_COMDAT |
141    COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
142    COFF::IMAGE_SCN_MEM_READ |
143    COFF::IMAGE_SCN_MEM_WRITE;
144
145  int Selection = COFF::IMAGE_COMDAT_SELECT_LARGEST;
146
147  const MCSection *Section = MCStreamer::getContext().getCOFFSection(
148    SectionName, Characteristics, Selection, SectionKind::getBSS());
149
150  MCSectionData &SectionData = getAssembler().getOrCreateSectionData(*Section);
151
152  if (SectionData.getAlignment() < ByteAlignment)
153    SectionData.setAlignment(ByteAlignment);
154
155  SymbolData.setExternal(External);
156
157  Symbol->setSection(*Section);
158
159  if (ByteAlignment != 1)
160      new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectionData);
161
162  SymbolData.setFragment(new MCFillFragment(0, 0, Size, &SectionData));
163}
164
165// MCStreamer interface
166
167void WinCOFFStreamer::InitSections() {
168  SetSectionText();
169  SetSectionData();
170  SetSectionBSS();
171  SetSectionText();
172}
173
174void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
175  assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
176  MCObjectStreamer::EmitLabel(Symbol);
177}
178
179void WinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
180  llvm_unreachable("not implemented");
181}
182
183void WinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
184  llvm_unreachable("not implemented");
185}
186
187void WinCOFFStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
188  assert((Symbol->isInSection()
189         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
190         : true) && "Got non COFF section in the COFF backend!");
191  // FIXME: This is all very ugly and depressing. What needs to happen here
192  // depends on quite a few things that are all part of relaxation, which we
193  // don't really even do.
194
195  if (Value->getKind() != MCExpr::SymbolRef) {
196    getAssembler().getOrCreateSymbolData(*Symbol);
197    AddValueSymbols(Value);
198    Symbol->setVariableValue(Value);
199  } else {
200    // FIXME: This is a horrible way to do this :(. This should really be
201    // handled after we are done with the MC* objects and immediately before
202    // writing out the object file when we know exactly what the symbol should
203    // look like in the coff symbol table. I'm not doing that now because the
204    // COFF object writer doesn't have a clearly defined separation between MC
205    // data structures, the object writers data structures, and the raw, POD,
206    // data structures that get written to disk.
207
208    // Copy over the aliased data.
209    MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
210    const MCSymbolData &RealSD = getAssembler().getOrCreateSymbolData(
211      dyn_cast<const MCSymbolRefExpr>(Value)->getSymbol());
212
213    // FIXME: This is particularly nasty because it breaks as soon as any data
214    // members of MCSymbolData change.
215    SD.CommonAlign     = RealSD.CommonAlign;
216    SD.CommonSize      = RealSD.CommonSize;
217    SD.Flags           = RealSD.Flags;
218    SD.Fragment        = RealSD.Fragment;
219    SD.Index           = RealSD.Index;
220    SD.IsExternal      = RealSD.IsExternal;
221    SD.IsPrivateExtern = RealSD.IsPrivateExtern;
222    SD.Offset          = RealSD.Offset;
223    SD.SymbolSize      = RealSD.SymbolSize;
224  }
225}
226
227void WinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
228                                          MCSymbolAttr Attribute) {
229  assert(Symbol && "Symbol must be non-null!");
230  assert((Symbol->isInSection()
231         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
232         : true) && "Got non COFF section in the COFF backend!");
233  switch (Attribute) {
234  case MCSA_WeakReference:
235  case MCSA_Weak: {
236      MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
237      SD.modifyFlags(COFF::SF_WeakExternal, COFF::SF_WeakExternal);
238      SD.setExternal(true);
239    }
240    break;
241
242  case MCSA_Global:
243    getAssembler().getOrCreateSymbolData(*Symbol).setExternal(true);
244    break;
245
246  default:
247    llvm_unreachable("unsupported attribute");
248  }
249}
250
251void WinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
252  llvm_unreachable("not implemented");
253}
254
255void WinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) {
256  assert((Symbol->isInSection()
257         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
258         : true) && "Got non COFF section in the COFF backend!");
259  assert(CurSymbol == NULL && "EndCOFFSymbolDef must be called between calls "
260                              "to BeginCOFFSymbolDef!");
261  CurSymbol = Symbol;
262}
263
264void WinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
265  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
266  assert((StorageClass & ~0xFF) == 0 && "StorageClass must only have data in "
267                                        "the first byte!");
268
269  getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
270    StorageClass << COFF::SF_ClassShift,
271    COFF::SF_ClassMask);
272}
273
274void WinCOFFStreamer::EmitCOFFSymbolType(int Type) {
275  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
276  assert((Type & ~0xFFFF) == 0 && "Type must only have data in the first 2 "
277                                  "bytes");
278
279  getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
280    Type << COFF::SF_TypeShift,
281    COFF::SF_TypeMask);
282}
283
284void WinCOFFStreamer::EndCOFFSymbolDef() {
285  assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
286  CurSymbol = NULL;
287}
288
289void WinCOFFStreamer::EmitCOFFSecRel32(MCSymbol const *Symbol)
290{
291  MCDataFragment *DF = getOrCreateDataFragment();
292
293  DF->addFixup(MCFixup::Create(DF->getContents().size(),
294                               MCSymbolRefExpr::Create (Symbol, getContext ()),
295                               FK_SecRel_4));
296  DF->getContents().resize(DF->getContents().size() + 4, 0);
297}
298
299void WinCOFFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
300  llvm_unreachable("not implemented");
301}
302
303void WinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
304                                       unsigned ByteAlignment) {
305  assert((Symbol->isInSection()
306         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
307         : true) && "Got non COFF section in the COFF backend!");
308  AddCommonSymbol(Symbol, Size, ByteAlignment, true);
309}
310
311void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
312                                            unsigned ByteAlignment) {
313  assert((Symbol->isInSection()
314         ? Symbol->getSection().getVariant() == MCSection::SV_COFF
315         : true) && "Got non COFF section in the COFF backend!");
316  AddCommonSymbol(Symbol, Size, ByteAlignment, false);
317}
318
319void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
320                                   uint64_t Size,unsigned ByteAlignment) {
321  llvm_unreachable("not implemented");
322}
323
324void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
325                                     uint64_t Size, unsigned ByteAlignment) {
326  llvm_unreachable("not implemented");
327}
328
329void WinCOFFStreamer::EmitFileDirective(StringRef Filename) {
330  // Ignore for now, linkers don't care, and proper debug
331  // info will be a much large effort.
332}
333
334void WinCOFFStreamer::EmitInstruction(const MCInst &Instruction) {
335  for (unsigned i = 0, e = Instruction.getNumOperands(); i != e; ++i)
336    if (Instruction.getOperand(i).isExpr())
337      AddValueSymbols(Instruction.getOperand(i).getExpr());
338
339  getCurrentSectionData()->setHasInstructions(true);
340
341  MCInstFragment *Fragment =
342    new MCInstFragment(Instruction, getCurrentSectionData());
343
344  raw_svector_ostream VecOS(Fragment->getCode());
345
346  getAssembler().getEmitter().EncodeInstruction(Instruction, VecOS,
347                                                Fragment->getFixups());
348}
349
350void WinCOFFStreamer::EmitWin64EHHandlerData() {
351  MCStreamer::EmitWin64EHHandlerData();
352
353  // We have to emit the unwind info now, because this directive
354  // actually switches to the .xdata section!
355  MCWin64EHUnwindEmitter::EmitUnwindInfo(*this, getCurrentW64UnwindInfo());
356}
357
358void WinCOFFStreamer::FinishImpl() {
359  EmitW64Tables();
360  MCObjectStreamer::FinishImpl();
361}
362
363namespace llvm
364{
365  MCStreamer *createWinCOFFStreamer(MCContext &Context,
366                                    MCAsmBackend &MAB,
367                                    MCCodeEmitter &CE,
368                                    raw_ostream &OS,
369                                    bool RelaxAll) {
370    WinCOFFStreamer *S = new WinCOFFStreamer(Context, MAB, CE, OS);
371    S->getAssembler().setRelaxAll(RelaxAll);
372    return S;
373  }
374}
375