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
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 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 void 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 EmitWin64EHHandlerData();
76 virtual void FinishImpl();
77
classof(const MCStreamer * S)78 static bool classof(const MCStreamer *S) {
79 return S->getKind() == SK_WinCOFFStreamer;
80 }
81
82 private:
EmitInstToData(const MCInst & Inst)83 virtual void EmitInstToData(const MCInst &Inst) {
84 MCDataFragment *DF = getOrCreateDataFragment();
85
86 SmallVector<MCFixup, 4> Fixups;
87 SmallString<256> Code;
88 raw_svector_ostream VecOS(Code);
89 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
90 VecOS.flush();
91
92 // Add the fixups and data.
93 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
94 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
95 DF->getFixups().push_back(Fixups[i]);
96 }
97 DF->getContents().append(Code.begin(), Code.end());
98 }
99
SetSection(StringRef Section,unsigned Characteristics,SectionKind Kind)100 void SetSection(StringRef Section,
101 unsigned Characteristics,
102 SectionKind Kind) {
103 SwitchSection(getContext().getCOFFSection(Section, Characteristics, Kind));
104 }
105
SetSectionText()106 void SetSectionText() {
107 SetSection(".text",
108 COFF::IMAGE_SCN_CNT_CODE
109 | COFF::IMAGE_SCN_MEM_EXECUTE
110 | COFF::IMAGE_SCN_MEM_READ,
111 SectionKind::getText());
112 EmitCodeAlignment(4, 0);
113 }
114
SetSectionData()115 void SetSectionData() {
116 SetSection(".data",
117 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
118 | COFF::IMAGE_SCN_MEM_READ
119 | COFF::IMAGE_SCN_MEM_WRITE,
120 SectionKind::getDataRel());
121 EmitCodeAlignment(4, 0);
122 }
123
SetSectionBSS()124 void SetSectionBSS() {
125 SetSection(".bss",
126 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA
127 | COFF::IMAGE_SCN_MEM_READ
128 | COFF::IMAGE_SCN_MEM_WRITE,
129 SectionKind::getBSS());
130 EmitCodeAlignment(4, 0);
131 }
132 };
133 } // end anonymous namespace.
134
WinCOFFStreamer(MCContext & Context,MCAsmBackend & MAB,MCCodeEmitter & CE,raw_ostream & OS)135 WinCOFFStreamer::WinCOFFStreamer(MCContext &Context, MCAsmBackend &MAB,
136 MCCodeEmitter &CE, raw_ostream &OS)
137 : MCObjectStreamer(SK_WinCOFFStreamer, Context, MAB, OS, &CE),
138 CurSymbol(NULL) {}
139
AddCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment,bool External)140 void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
141 unsigned ByteAlignment, bool External) {
142 assert(!Symbol->isInSection() && "Symbol must not already have a section!");
143
144 std::string SectionName(".bss$linkonce");
145 SectionName.append(Symbol->getName().begin(), Symbol->getName().end());
146
147 MCSymbolData &SymbolData = getAssembler().getOrCreateSymbolData(*Symbol);
148
149 unsigned Characteristics =
150 COFF::IMAGE_SCN_LNK_COMDAT |
151 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
152 COFF::IMAGE_SCN_MEM_READ |
153 COFF::IMAGE_SCN_MEM_WRITE;
154
155 int Selection = COFF::IMAGE_COMDAT_SELECT_LARGEST;
156
157 const MCSection *Section = MCStreamer::getContext().getCOFFSection(
158 SectionName, Characteristics, SectionKind::getBSS(), Selection);
159
160 MCSectionData &SectionData = getAssembler().getOrCreateSectionData(*Section);
161
162 if (SectionData.getAlignment() < ByteAlignment)
163 SectionData.setAlignment(ByteAlignment);
164
165 SymbolData.setExternal(External);
166
167 Symbol->setSection(*Section);
168
169 if (ByteAlignment != 1)
170 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectionData);
171
172 SymbolData.setFragment(new MCFillFragment(0, 0, Size, &SectionData));
173 }
174
175 // MCStreamer interface
176
InitToTextSection()177 void WinCOFFStreamer::InitToTextSection() {
178 SetSectionText();
179 }
180
InitSections()181 void WinCOFFStreamer::InitSections() {
182 SetSectionText();
183 SetSectionData();
184 SetSectionBSS();
185 SetSectionText();
186 }
187
EmitLabel(MCSymbol * Symbol)188 void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
189 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
190 MCObjectStreamer::EmitLabel(Symbol);
191 }
192
EmitDebugLabel(MCSymbol * Symbol)193 void WinCOFFStreamer::EmitDebugLabel(MCSymbol *Symbol) {
194 EmitLabel(Symbol);
195 }
EmitAssemblerFlag(MCAssemblerFlag Flag)196 void WinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
197 llvm_unreachable("not implemented");
198 }
199
EmitThumbFunc(MCSymbol * Func)200 void WinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
201 llvm_unreachable("not implemented");
202 }
203
EmitSymbolAttribute(MCSymbol * Symbol,MCSymbolAttr Attribute)204 void WinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
205 MCSymbolAttr Attribute) {
206 assert(Symbol && "Symbol must be non-null!");
207 assert((Symbol->isInSection()
208 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
209 : true) && "Got non COFF section in the COFF backend!");
210 switch (Attribute) {
211 case MCSA_WeakReference:
212 case MCSA_Weak: {
213 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
214 SD.modifyFlags(COFF::SF_WeakExternal, COFF::SF_WeakExternal);
215 SD.setExternal(true);
216 }
217 break;
218
219 case MCSA_Global:
220 getAssembler().getOrCreateSymbolData(*Symbol).setExternal(true);
221 break;
222
223 default:
224 llvm_unreachable("unsupported attribute");
225 }
226 }
227
EmitSymbolDesc(MCSymbol * Symbol,unsigned DescValue)228 void WinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
229 llvm_unreachable("not implemented");
230 }
231
BeginCOFFSymbolDef(MCSymbol const * Symbol)232 void WinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) {
233 assert((Symbol->isInSection()
234 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
235 : true) && "Got non COFF section in the COFF backend!");
236 assert(CurSymbol == NULL && "EndCOFFSymbolDef must be called between calls "
237 "to BeginCOFFSymbolDef!");
238 CurSymbol = Symbol;
239 }
240
EmitCOFFSymbolStorageClass(int StorageClass)241 void WinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
242 assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
243 assert((StorageClass & ~0xFF) == 0 && "StorageClass must only have data in "
244 "the first byte!");
245
246 getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
247 StorageClass << COFF::SF_ClassShift,
248 COFF::SF_ClassMask);
249 }
250
EmitCOFFSymbolType(int Type)251 void WinCOFFStreamer::EmitCOFFSymbolType(int Type) {
252 assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
253 assert((Type & ~0xFFFF) == 0 && "Type must only have data in the first 2 "
254 "bytes");
255
256 getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
257 Type << COFF::SF_TypeShift,
258 COFF::SF_TypeMask);
259 }
260
EndCOFFSymbolDef()261 void WinCOFFStreamer::EndCOFFSymbolDef() {
262 assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
263 CurSymbol = NULL;
264 }
265
EmitCOFFSecRel32(MCSymbol const * Symbol)266 void WinCOFFStreamer::EmitCOFFSecRel32(MCSymbol const *Symbol)
267 {
268 MCDataFragment *DF = getOrCreateDataFragment();
269
270 DF->getFixups().push_back(
271 MCFixup::Create(DF->getContents().size(),
272 MCSymbolRefExpr::Create (Symbol, getContext ()),
273 FK_SecRel_4));
274 DF->getContents().resize(DF->getContents().size() + 4, 0);
275 }
276
EmitELFSize(MCSymbol * Symbol,const MCExpr * Value)277 void WinCOFFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
278 llvm_unreachable("not implemented");
279 }
280
EmitCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)281 void WinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
282 unsigned ByteAlignment) {
283 assert((Symbol->isInSection()
284 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
285 : true) && "Got non COFF section in the COFF backend!");
286 AddCommonSymbol(Symbol, Size, ByteAlignment, true);
287 }
288
EmitLocalCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)289 void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
290 unsigned ByteAlignment) {
291 assert((Symbol->isInSection()
292 ? Symbol->getSection().getVariant() == MCSection::SV_COFF
293 : true) && "Got non COFF section in the COFF backend!");
294 AddCommonSymbol(Symbol, Size, ByteAlignment, false);
295 }
296
EmitZerofill(const MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)297 void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
298 uint64_t Size,unsigned ByteAlignment) {
299 llvm_unreachable("not implemented");
300 }
301
EmitTBSSSymbol(const MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)302 void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
303 uint64_t Size, unsigned ByteAlignment) {
304 llvm_unreachable("not implemented");
305 }
306
EmitFileDirective(StringRef Filename)307 void WinCOFFStreamer::EmitFileDirective(StringRef Filename) {
308 // Ignore for now, linkers don't care, and proper debug
309 // info will be a much large effort.
310 }
311
EmitWin64EHHandlerData()312 void WinCOFFStreamer::EmitWin64EHHandlerData() {
313 MCStreamer::EmitWin64EHHandlerData();
314
315 // We have to emit the unwind info now, because this directive
316 // actually switches to the .xdata section!
317 MCWin64EHUnwindEmitter::EmitUnwindInfo(*this, getCurrentW64UnwindInfo());
318 }
319
FinishImpl()320 void WinCOFFStreamer::FinishImpl() {
321 EmitW64Tables();
322 MCObjectStreamer::FinishImpl();
323 }
324
325 namespace llvm
326 {
createWinCOFFStreamer(MCContext & Context,MCAsmBackend & MAB,MCCodeEmitter & CE,raw_ostream & OS,bool RelaxAll)327 MCStreamer *createWinCOFFStreamer(MCContext &Context,
328 MCAsmBackend &MAB,
329 MCCodeEmitter &CE,
330 raw_ostream &OS,
331 bool RelaxAll) {
332 WinCOFFStreamer *S = new WinCOFFStreamer(Context, MAB, CE, OS);
333 S->getAssembler().setRelaxAll(RelaxAll);
334 return S;
335 }
336 }
337