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/MC/MCWin64EH.h"
27 #include "llvm/MC/MCAsmBackend.h"
28
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
35 using namespace llvm;
36
37 namespace {
38 class WinCOFFStreamer : public MCObjectStreamer {
39 public:
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 unsigned Size,unsigned ByteAlignment);
71 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
72 uint64_t Size, unsigned ByteAlignment);
73 virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
74 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
75 unsigned ValueSize, unsigned MaxBytesToEmit);
76 virtual void EmitCodeAlignment(unsigned ByteAlignment,
77 unsigned MaxBytesToEmit);
78 virtual void EmitFileDirective(StringRef Filename);
79 virtual void EmitInstruction(const MCInst &Instruction);
80 virtual void EmitWin64EHHandlerData();
81 virtual void FinishImpl();
82
83 private:
EmitInstToFragment(const MCInst & Inst)84 virtual void EmitInstToFragment(const MCInst &Inst) {
85 llvm_unreachable("Not used by WinCOFF.");
86 }
EmitInstToData(const MCInst & Inst)87 virtual void EmitInstToData(const MCInst &Inst) {
88 llvm_unreachable("Not used by WinCOFF.");
89 }
90
SetSection(StringRef Section,unsigned Characteristics,SectionKind Kind)91 void SetSection(StringRef Section,
92 unsigned Characteristics,
93 SectionKind Kind) {
94 SwitchSection(getContext().getCOFFSection(Section, Characteristics, Kind));
95 }
96
SetSectionText()97 void SetSectionText() {
98 SetSection(".text",
99 COFF::IMAGE_SCN_CNT_CODE
100 | COFF::IMAGE_SCN_MEM_EXECUTE
101 | COFF::IMAGE_SCN_MEM_READ,
102 SectionKind::getText());
103 EmitCodeAlignment(4, 0);
104 }
105
SetSectionData()106 void SetSectionData() {
107 SetSection(".data",
108 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
109 | COFF::IMAGE_SCN_MEM_READ
110 | COFF::IMAGE_SCN_MEM_WRITE,
111 SectionKind::getDataRel());
112 EmitCodeAlignment(4, 0);
113 }
114
SetSectionBSS()115 void SetSectionBSS() {
116 SetSection(".bss",
117 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA
118 | COFF::IMAGE_SCN_MEM_READ
119 | COFF::IMAGE_SCN_MEM_WRITE,
120 SectionKind::getBSS());
121 EmitCodeAlignment(4, 0);
122 }
123
124 };
125 } // end anonymous namespace.
126
WinCOFFStreamer(MCContext & Context,MCAsmBackend & MAB,MCCodeEmitter & CE,raw_ostream & OS)127 WinCOFFStreamer::WinCOFFStreamer(MCContext &Context,
128 MCAsmBackend &MAB,
129 MCCodeEmitter &CE,
130 raw_ostream &OS)
131 : MCObjectStreamer(Context, MAB, OS, &CE)
132 , CurSymbol(NULL) {
133 }
134
AddCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment,bool External)135 void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
136 unsigned ByteAlignment, bool External) {
137 assert(!Symbol->isInSection() && "Symbol must not already have a section!");
138
139 std::string SectionName(".bss$linkonce");
140 SectionName.append(Symbol->getName().begin(), Symbol->getName().end());
141
142 MCSymbolData &SymbolData = getAssembler().getOrCreateSymbolData(*Symbol);
143
144 unsigned Characteristics =
145 COFF::IMAGE_SCN_LNK_COMDAT |
146 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
147 COFF::IMAGE_SCN_MEM_READ |
148 COFF::IMAGE_SCN_MEM_WRITE;
149
150 int Selection = COFF::IMAGE_COMDAT_SELECT_LARGEST;
151
152 const MCSection *Section = MCStreamer::getContext().getCOFFSection(
153 SectionName, Characteristics, Selection, SectionKind::getBSS());
154
155 MCSectionData &SectionData = getAssembler().getOrCreateSectionData(*Section);
156
157 if (SectionData.getAlignment() < ByteAlignment)
158 SectionData.setAlignment(ByteAlignment);
159
160 SymbolData.setExternal(External);
161
162 Symbol->setSection(*Section);
163
164 if (ByteAlignment != 1)
165 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectionData);
166
167 SymbolData.setFragment(new MCFillFragment(0, 0, Size, &SectionData));
168 }
169
170 // MCStreamer interface
171
InitSections()172 void WinCOFFStreamer::InitSections() {
173 SetSectionText();
174 SetSectionData();
175 SetSectionBSS();
176 SetSectionText();
177 }
178
EmitLabel(MCSymbol * Symbol)179 void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
180 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
181 MCObjectStreamer::EmitLabel(Symbol);
182 }
183
EmitAssemblerFlag(MCAssemblerFlag Flag)184 void WinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
185 llvm_unreachable("not implemented");
186 }
187
EmitThumbFunc(MCSymbol * Func)188 void WinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
189 llvm_unreachable("not implemented");
190 }
191
EmitAssignment(MCSymbol * Symbol,const MCExpr * Value)192 void WinCOFFStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
193 assert((Symbol->isInSection()
194 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
195 : true) && "Got non COFF section in the COFF backend!");
196 // FIXME: This is all very ugly and depressing. What needs to happen here
197 // depends on quite a few things that are all part of relaxation, which we
198 // don't really even do.
199
200 if (Value->getKind() != MCExpr::SymbolRef) {
201 // TODO: This is exactly the same as MachOStreamer. Consider merging into
202 // MCObjectStreamer.
203 getAssembler().getOrCreateSymbolData(*Symbol);
204 AddValueSymbols(Value);
205 Symbol->setVariableValue(Value);
206 } else {
207 // FIXME: This is a horrible way to do this :(. This should really be
208 // handled after we are done with the MC* objects and immediately before
209 // writing out the object file when we know exactly what the symbol should
210 // look like in the coff symbol table. I'm not doing that now because the
211 // COFF object writer doesn't have a clearly defined separation between MC
212 // data structures, the object writers data structures, and the raw, POD,
213 // data structures that get written to disk.
214
215 // Copy over the aliased data.
216 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
217 const MCSymbolData &RealSD = getAssembler().getOrCreateSymbolData(
218 dyn_cast<const MCSymbolRefExpr>(Value)->getSymbol());
219
220 // FIXME: This is particularly nasty because it breaks as soon as any data
221 // members of MCSymbolData change.
222 SD.CommonAlign = RealSD.CommonAlign;
223 SD.CommonSize = RealSD.CommonSize;
224 SD.Flags = RealSD.Flags;
225 SD.Fragment = RealSD.Fragment;
226 SD.Index = RealSD.Index;
227 SD.IsExternal = RealSD.IsExternal;
228 SD.IsPrivateExtern = RealSD.IsPrivateExtern;
229 SD.Offset = RealSD.Offset;
230 SD.SymbolSize = RealSD.SymbolSize;
231 }
232 }
233
EmitSymbolAttribute(MCSymbol * Symbol,MCSymbolAttr Attribute)234 void WinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
235 MCSymbolAttr Attribute) {
236 assert(Symbol && "Symbol must be non-null!");
237 assert((Symbol->isInSection()
238 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
239 : true) && "Got non COFF section in the COFF backend!");
240 switch (Attribute) {
241 case MCSA_WeakReference:
242 case MCSA_Weak: {
243 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
244 SD.modifyFlags(COFF::SF_WeakExternal, COFF::SF_WeakExternal);
245 SD.setExternal(true);
246 }
247 break;
248
249 case MCSA_Global:
250 getAssembler().getOrCreateSymbolData(*Symbol).setExternal(true);
251 break;
252
253 default:
254 llvm_unreachable("unsupported attribute");
255 }
256 }
257
EmitSymbolDesc(MCSymbol * Symbol,unsigned DescValue)258 void WinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
259 llvm_unreachable("not implemented");
260 }
261
BeginCOFFSymbolDef(MCSymbol const * Symbol)262 void WinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) {
263 assert((Symbol->isInSection()
264 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
265 : true) && "Got non COFF section in the COFF backend!");
266 assert(CurSymbol == NULL && "EndCOFFSymbolDef must be called between calls "
267 "to BeginCOFFSymbolDef!");
268 CurSymbol = Symbol;
269 }
270
EmitCOFFSymbolStorageClass(int StorageClass)271 void WinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
272 assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
273 assert((StorageClass & ~0xFF) == 0 && "StorageClass must only have data in "
274 "the first byte!");
275
276 getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
277 StorageClass << COFF::SF_ClassShift,
278 COFF::SF_ClassMask);
279 }
280
EmitCOFFSymbolType(int Type)281 void WinCOFFStreamer::EmitCOFFSymbolType(int Type) {
282 assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
283 assert((Type & ~0xFFFF) == 0 && "Type must only have data in the first 2 "
284 "bytes");
285
286 getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
287 Type << COFF::SF_TypeShift,
288 COFF::SF_TypeMask);
289 }
290
EndCOFFSymbolDef()291 void WinCOFFStreamer::EndCOFFSymbolDef() {
292 assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
293 CurSymbol = NULL;
294 }
295
EmitCOFFSecRel32(MCSymbol const * Symbol)296 void WinCOFFStreamer::EmitCOFFSecRel32(MCSymbol const *Symbol)
297 {
298 MCDataFragment *DF = getOrCreateDataFragment();
299
300 DF->addFixup(MCFixup::Create(DF->getContents().size(),
301 MCSymbolRefExpr::Create (Symbol, getContext ()),
302 FK_SecRel_4));
303 DF->getContents().resize(DF->getContents().size() + 4, 0);
304 }
305
EmitELFSize(MCSymbol * Symbol,const MCExpr * Value)306 void WinCOFFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
307 llvm_unreachable("not implemented");
308 }
309
EmitCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)310 void WinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
311 unsigned ByteAlignment) {
312 assert((Symbol->isInSection()
313 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
314 : true) && "Got non COFF section in the COFF backend!");
315 AddCommonSymbol(Symbol, Size, ByteAlignment, true);
316 }
317
EmitLocalCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)318 void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
319 unsigned ByteAlignment) {
320 assert((Symbol->isInSection()
321 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
322 : true) && "Got non COFF section in the COFF backend!");
323 AddCommonSymbol(Symbol, Size, ByteAlignment, false);
324 }
325
EmitZerofill(const MCSection * Section,MCSymbol * Symbol,unsigned Size,unsigned ByteAlignment)326 void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
327 unsigned Size,unsigned ByteAlignment) {
328 llvm_unreachable("not implemented");
329 }
330
EmitTBSSSymbol(const MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)331 void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
332 uint64_t Size, unsigned ByteAlignment) {
333 llvm_unreachable("not implemented");
334 }
335
EmitBytes(StringRef Data,unsigned AddrSpace)336 void WinCOFFStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
337 // TODO: This is copied exactly from the MachOStreamer. Consider merging into
338 // MCObjectStreamer?
339 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
340 }
341
EmitValueToAlignment(unsigned ByteAlignment,int64_t Value,unsigned ValueSize,unsigned MaxBytesToEmit)342 void WinCOFFStreamer::EmitValueToAlignment(unsigned ByteAlignment,
343 int64_t Value,
344 unsigned ValueSize,
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 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
351 getCurrentSectionData());
352
353 // Update the maximum alignment on the current section if necessary.
354 if (ByteAlignment > getCurrentSectionData()->getAlignment())
355 getCurrentSectionData()->setAlignment(ByteAlignment);
356 }
357
EmitCodeAlignment(unsigned ByteAlignment,unsigned MaxBytesToEmit)358 void WinCOFFStreamer::EmitCodeAlignment(unsigned ByteAlignment,
359 unsigned MaxBytesToEmit) {
360 // TODO: This is copied exactly from the MachOStreamer. Consider merging into
361 // MCObjectStreamer?
362 if (MaxBytesToEmit == 0)
363 MaxBytesToEmit = ByteAlignment;
364 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
365 getCurrentSectionData());
366 F->setEmitNops(true);
367
368 // Update the maximum alignment on the current section if necessary.
369 if (ByteAlignment > getCurrentSectionData()->getAlignment())
370 getCurrentSectionData()->setAlignment(ByteAlignment);
371 }
372
EmitFileDirective(StringRef Filename)373 void WinCOFFStreamer::EmitFileDirective(StringRef Filename) {
374 // Ignore for now, linkers don't care, and proper debug
375 // info will be a much large effort.
376 }
377
EmitInstruction(const MCInst & Instruction)378 void WinCOFFStreamer::EmitInstruction(const MCInst &Instruction) {
379 for (unsigned i = 0, e = Instruction.getNumOperands(); i != e; ++i)
380 if (Instruction.getOperand(i).isExpr())
381 AddValueSymbols(Instruction.getOperand(i).getExpr());
382
383 getCurrentSectionData()->setHasInstructions(true);
384
385 MCInstFragment *Fragment =
386 new MCInstFragment(Instruction, getCurrentSectionData());
387
388 raw_svector_ostream VecOS(Fragment->getCode());
389
390 getAssembler().getEmitter().EncodeInstruction(Instruction, VecOS,
391 Fragment->getFixups());
392 }
393
EmitWin64EHHandlerData()394 void WinCOFFStreamer::EmitWin64EHHandlerData() {
395 MCStreamer::EmitWin64EHHandlerData();
396
397 // We have to emit the unwind info now, because this directive
398 // actually switches to the .xdata section!
399 MCWin64EHUnwindEmitter::EmitUnwindInfo(*this, getCurrentW64UnwindInfo());
400 }
401
FinishImpl()402 void WinCOFFStreamer::FinishImpl() {
403 EmitW64Tables();
404 MCObjectStreamer::FinishImpl();
405 }
406
407 namespace llvm
408 {
createWinCOFFStreamer(MCContext & Context,MCAsmBackend & MAB,MCCodeEmitter & CE,raw_ostream & OS,bool RelaxAll)409 MCStreamer *createWinCOFFStreamer(MCContext &Context,
410 MCAsmBackend &MAB,
411 MCCodeEmitter &CE,
412 raw_ostream &OS,
413 bool RelaxAll) {
414 WinCOFFStreamer *S = new WinCOFFStreamer(Context, MAB, CE, OS);
415 S->getAssembler().setRelaxAll(RelaxAll);
416 return S;
417 }
418 }
419