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/Target/TargetRegistry.h"
28 #include "llvm/Target/TargetAsmBackend.h"
29 #include "llvm/ADT/StringMap.h"
30
31 #include "llvm/Support/COFF.h"
32 #include "llvm/Support/Debug.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/raw_ostream.h"
35 using namespace llvm;
36
37 namespace {
38 class WinCOFFStreamer : public MCObjectStreamer {
39 public:
40 MCSymbol const *CurSymbol;
41
42 WinCOFFStreamer(MCContext &Context,
43 TargetAsmBackend &TAB,
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 EmitELFSize(MCSymbol *Symbol, const MCExpr *Value);
64 virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
65 unsigned ByteAlignment);
66 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size);
67 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
68 unsigned Size,unsigned ByteAlignment);
69 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
70 uint64_t Size, unsigned ByteAlignment);
71 virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
72 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
73 unsigned ValueSize, unsigned MaxBytesToEmit);
74 virtual void EmitCodeAlignment(unsigned ByteAlignment,
75 unsigned MaxBytesToEmit);
76 virtual void EmitFileDirective(StringRef Filename);
77 virtual void EmitInstruction(const MCInst &Instruction);
78 virtual void EmitWin64EHHandlerData();
79 virtual void Finish();
80
81 private:
EmitInstToFragment(const MCInst & Inst)82 virtual void EmitInstToFragment(const MCInst &Inst) {
83 llvm_unreachable("Not used by WinCOFF.");
84 }
EmitInstToData(const MCInst & Inst)85 virtual void EmitInstToData(const MCInst &Inst) {
86 llvm_unreachable("Not used by WinCOFF.");
87 }
88
SetSection(StringRef Section,unsigned Characteristics,SectionKind Kind)89 void SetSection(StringRef Section,
90 unsigned Characteristics,
91 SectionKind Kind) {
92 SwitchSection(getContext().getCOFFSection(Section, Characteristics, Kind));
93 }
94
SetSectionText()95 void SetSectionText() {
96 SetSection(".text",
97 COFF::IMAGE_SCN_CNT_CODE
98 | COFF::IMAGE_SCN_MEM_EXECUTE
99 | COFF::IMAGE_SCN_MEM_READ,
100 SectionKind::getText());
101 EmitCodeAlignment(4, 0);
102 }
103
SetSectionData()104 void SetSectionData() {
105 SetSection(".data",
106 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
107 | COFF::IMAGE_SCN_MEM_READ
108 | COFF::IMAGE_SCN_MEM_WRITE,
109 SectionKind::getDataRel());
110 EmitCodeAlignment(4, 0);
111 }
112
SetSectionBSS()113 void SetSectionBSS() {
114 SetSection(".bss",
115 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA
116 | COFF::IMAGE_SCN_MEM_READ
117 | COFF::IMAGE_SCN_MEM_WRITE,
118 SectionKind::getBSS());
119 EmitCodeAlignment(4, 0);
120 }
121
122 };
123 } // end anonymous namespace.
124
WinCOFFStreamer(MCContext & Context,TargetAsmBackend & TAB,MCCodeEmitter & CE,raw_ostream & OS)125 WinCOFFStreamer::WinCOFFStreamer(MCContext &Context,
126 TargetAsmBackend &TAB,
127 MCCodeEmitter &CE,
128 raw_ostream &OS)
129 : MCObjectStreamer(Context, TAB, OS, &CE)
130 , CurSymbol(NULL) {
131 }
132
AddCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment,bool External)133 void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
134 unsigned ByteAlignment, bool External) {
135 assert(!Symbol->isInSection() && "Symbol must not already have a section!");
136
137 std::string SectionName(".bss$linkonce");
138 SectionName.append(Symbol->getName().begin(), Symbol->getName().end());
139
140 MCSymbolData &SymbolData = getAssembler().getOrCreateSymbolData(*Symbol);
141
142 unsigned Characteristics =
143 COFF::IMAGE_SCN_LNK_COMDAT |
144 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
145 COFF::IMAGE_SCN_MEM_READ |
146 COFF::IMAGE_SCN_MEM_WRITE;
147
148 int Selection = COFF::IMAGE_COMDAT_SELECT_LARGEST;
149
150 const MCSection *Section = MCStreamer::getContext().getCOFFSection(
151 SectionName, Characteristics, Selection, SectionKind::getBSS());
152
153 MCSectionData &SectionData = getAssembler().getOrCreateSectionData(*Section);
154
155 if (SectionData.getAlignment() < ByteAlignment)
156 SectionData.setAlignment(ByteAlignment);
157
158 SymbolData.setExternal(External);
159
160 Symbol->setSection(*Section);
161
162 if (ByteAlignment != 1)
163 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectionData);
164
165 SymbolData.setFragment(new MCFillFragment(0, 0, Size, &SectionData));
166 }
167
168 // MCStreamer interface
169
InitSections()170 void WinCOFFStreamer::InitSections() {
171 SetSectionText();
172 SetSectionData();
173 SetSectionBSS();
174 SetSectionText();
175 }
176
EmitLabel(MCSymbol * Symbol)177 void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
178 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
179 MCObjectStreamer::EmitLabel(Symbol);
180 }
181
EmitAssemblerFlag(MCAssemblerFlag Flag)182 void WinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
183 llvm_unreachable("not implemented");
184 }
185
EmitThumbFunc(MCSymbol * Func)186 void WinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
187 llvm_unreachable("not implemented");
188 }
189
EmitAssignment(MCSymbol * Symbol,const MCExpr * Value)190 void WinCOFFStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
191 assert((Symbol->isInSection()
192 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
193 : true) && "Got non COFF section in the COFF backend!");
194 // FIXME: This is all very ugly and depressing. What needs to happen here
195 // depends on quite a few things that are all part of relaxation, which we
196 // don't really even do.
197
198 if (Value->getKind() != MCExpr::SymbolRef) {
199 // TODO: This is exactly the same as MachOStreamer. Consider merging into
200 // MCObjectStreamer.
201 getAssembler().getOrCreateSymbolData(*Symbol);
202 AddValueSymbols(Value);
203 Symbol->setVariableValue(Value);
204 } else {
205 // FIXME: This is a horrible way to do this :(. This should really be
206 // handled after we are done with the MC* objects and immediately before
207 // writing out the object file when we know exactly what the symbol should
208 // look like in the coff symbol table. I'm not doing that now because the
209 // COFF object writer doesn't have a clearly defined separation between MC
210 // data structures, the object writers data structures, and the raw, POD,
211 // data structures that get written to disk.
212
213 // Copy over the aliased data.
214 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
215 const MCSymbolData &RealSD = getAssembler().getOrCreateSymbolData(
216 dyn_cast<const MCSymbolRefExpr>(Value)->getSymbol());
217
218 // FIXME: This is particularly nasty because it breaks as soon as any data
219 // members of MCSymbolData change.
220 SD.CommonAlign = RealSD.CommonAlign;
221 SD.CommonSize = RealSD.CommonSize;
222 SD.Flags = RealSD.Flags;
223 SD.Fragment = RealSD.Fragment;
224 SD.Index = RealSD.Index;
225 SD.IsExternal = RealSD.IsExternal;
226 SD.IsPrivateExtern = RealSD.IsPrivateExtern;
227 SD.Offset = RealSD.Offset;
228 SD.SymbolSize = RealSD.SymbolSize;
229 }
230 }
231
EmitSymbolAttribute(MCSymbol * Symbol,MCSymbolAttr Attribute)232 void WinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
233 MCSymbolAttr Attribute) {
234 assert(Symbol && "Symbol must be non-null!");
235 assert((Symbol->isInSection()
236 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
237 : true) && "Got non COFF section in the COFF backend!");
238 switch (Attribute) {
239 case MCSA_WeakReference:
240 case MCSA_Weak: {
241 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
242 SD.modifyFlags(COFF::SF_WeakExternal, COFF::SF_WeakExternal);
243 SD.setExternal(true);
244 }
245 break;
246
247 case MCSA_Global:
248 getAssembler().getOrCreateSymbolData(*Symbol).setExternal(true);
249 break;
250
251 default:
252 llvm_unreachable("unsupported attribute");
253 break;
254 }
255 }
256
EmitSymbolDesc(MCSymbol * Symbol,unsigned DescValue)257 void WinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
258 llvm_unreachable("not implemented");
259 }
260
BeginCOFFSymbolDef(MCSymbol const * Symbol)261 void WinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) {
262 assert((Symbol->isInSection()
263 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
264 : true) && "Got non COFF section in the COFF backend!");
265 assert(CurSymbol == NULL && "EndCOFFSymbolDef must be called between calls "
266 "to BeginCOFFSymbolDef!");
267 CurSymbol = Symbol;
268 }
269
EmitCOFFSymbolStorageClass(int StorageClass)270 void WinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
271 assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
272 assert((StorageClass & ~0xFF) == 0 && "StorageClass must only have data in "
273 "the first byte!");
274
275 getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
276 StorageClass << COFF::SF_ClassShift,
277 COFF::SF_ClassMask);
278 }
279
EmitCOFFSymbolType(int Type)280 void WinCOFFStreamer::EmitCOFFSymbolType(int Type) {
281 assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
282 assert((Type & ~0xFFFF) == 0 && "Type must only have data in the first 2 "
283 "bytes");
284
285 getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
286 Type << COFF::SF_TypeShift,
287 COFF::SF_TypeMask);
288 }
289
EndCOFFSymbolDef()290 void WinCOFFStreamer::EndCOFFSymbolDef() {
291 assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
292 CurSymbol = NULL;
293 }
294
EmitELFSize(MCSymbol * Symbol,const MCExpr * Value)295 void WinCOFFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
296 llvm_unreachable("not implemented");
297 }
298
EmitCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)299 void WinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
300 unsigned ByteAlignment) {
301 assert((Symbol->isInSection()
302 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
303 : true) && "Got non COFF section in the COFF backend!");
304 AddCommonSymbol(Symbol, Size, ByteAlignment, true);
305 }
306
EmitLocalCommonSymbol(MCSymbol * Symbol,uint64_t Size)307 void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
308 assert((Symbol->isInSection()
309 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
310 : true) && "Got non COFF section in the COFF backend!");
311 AddCommonSymbol(Symbol, Size, 1, false);
312 }
313
EmitZerofill(const MCSection * Section,MCSymbol * Symbol,unsigned Size,unsigned ByteAlignment)314 void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
315 unsigned Size,unsigned ByteAlignment) {
316 llvm_unreachable("not implemented");
317 }
318
EmitTBSSSymbol(const MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)319 void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
320 uint64_t Size, unsigned ByteAlignment) {
321 llvm_unreachable("not implemented");
322 }
323
EmitBytes(StringRef Data,unsigned AddrSpace)324 void WinCOFFStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
325 // TODO: This is copied exactly from the MachOStreamer. Consider merging into
326 // MCObjectStreamer?
327 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
328 }
329
EmitValueToAlignment(unsigned ByteAlignment,int64_t Value,unsigned ValueSize,unsigned MaxBytesToEmit)330 void WinCOFFStreamer::EmitValueToAlignment(unsigned ByteAlignment,
331 int64_t Value,
332 unsigned ValueSize,
333 unsigned MaxBytesToEmit) {
334 // TODO: This is copied exactly from the MachOStreamer. Consider merging into
335 // MCObjectStreamer?
336 if (MaxBytesToEmit == 0)
337 MaxBytesToEmit = ByteAlignment;
338 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
339 getCurrentSectionData());
340
341 // Update the maximum alignment on the current section if necessary.
342 if (ByteAlignment > getCurrentSectionData()->getAlignment())
343 getCurrentSectionData()->setAlignment(ByteAlignment);
344 }
345
EmitCodeAlignment(unsigned ByteAlignment,unsigned MaxBytesToEmit)346 void WinCOFFStreamer::EmitCodeAlignment(unsigned ByteAlignment,
347 unsigned MaxBytesToEmit) {
348 // TODO: This is copied exactly from the MachOStreamer. Consider merging into
349 // MCObjectStreamer?
350 if (MaxBytesToEmit == 0)
351 MaxBytesToEmit = ByteAlignment;
352 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
353 getCurrentSectionData());
354 F->setEmitNops(true);
355
356 // Update the maximum alignment on the current section if necessary.
357 if (ByteAlignment > getCurrentSectionData()->getAlignment())
358 getCurrentSectionData()->setAlignment(ByteAlignment);
359 }
360
EmitFileDirective(StringRef Filename)361 void WinCOFFStreamer::EmitFileDirective(StringRef Filename) {
362 // Ignore for now, linkers don't care, and proper debug
363 // info will be a much large effort.
364 }
365
EmitInstruction(const MCInst & Instruction)366 void WinCOFFStreamer::EmitInstruction(const MCInst &Instruction) {
367 for (unsigned i = 0, e = Instruction.getNumOperands(); i != e; ++i)
368 if (Instruction.getOperand(i).isExpr())
369 AddValueSymbols(Instruction.getOperand(i).getExpr());
370
371 getCurrentSectionData()->setHasInstructions(true);
372
373 MCInstFragment *Fragment =
374 new MCInstFragment(Instruction, getCurrentSectionData());
375
376 raw_svector_ostream VecOS(Fragment->getCode());
377
378 getAssembler().getEmitter().EncodeInstruction(Instruction, VecOS,
379 Fragment->getFixups());
380 }
381
EmitWin64EHHandlerData()382 void WinCOFFStreamer::EmitWin64EHHandlerData() {
383 MCStreamer::EmitWin64EHHandlerData();
384
385 // We have to emit the unwind info now, because this directive
386 // actually switches to the .xdata section!
387 MCWin64EHUnwindEmitter::EmitUnwindInfo(*this, getCurrentW64UnwindInfo());
388 }
389
Finish()390 void WinCOFFStreamer::Finish() {
391 EmitW64Tables();
392 MCObjectStreamer::Finish();
393 }
394
395 namespace llvm
396 {
createWinCOFFStreamer(MCContext & Context,TargetAsmBackend & TAB,MCCodeEmitter & CE,raw_ostream & OS,bool RelaxAll)397 MCStreamer *createWinCOFFStreamer(MCContext &Context,
398 TargetAsmBackend &TAB,
399 MCCodeEmitter &CE,
400 raw_ostream &OS,
401 bool RelaxAll) {
402 WinCOFFStreamer *S = new WinCOFFStreamer(Context, TAB, CE, OS);
403 S->getAssembler().setRelaxAll(RelaxAll);
404 return S;
405 }
406 }
407