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 Windows COFF object file streamer.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm/MC/MCAsmBackend.h"
15 #include "llvm/MC/MCAsmLayout.h"
16 #include "llvm/MC/MCAssembler.h"
17 #include "llvm/MC/MCCodeEmitter.h"
18 #include "llvm/MC/MCContext.h"
19 #include "llvm/MC/MCExpr.h"
20 #include "llvm/MC/MCObjectFileInfo.h"
21 #include "llvm/MC/MCObjectStreamer.h"
22 #include "llvm/MC/MCSection.h"
23 #include "llvm/MC/MCSectionCOFF.h"
24 #include "llvm/MC/MCStreamer.h"
25 #include "llvm/MC/MCSymbolCOFF.h"
26 #include "llvm/MC/MCValue.h"
27 #include "llvm/MC/MCWinCOFFStreamer.h"
28 #include "llvm/Support/COFF.h"
29 #include "llvm/Support/Debug.h"
30 #include "llvm/Support/ErrorHandling.h"
31 #include "llvm/Support/MathExtras.h"
32 #include "llvm/Support/TargetRegistry.h"
33 #include "llvm/Support/raw_ostream.h"
34
35 using namespace llvm;
36
37 #define DEBUG_TYPE "WinCOFFStreamer"
38
39 namespace llvm {
MCWinCOFFStreamer(MCContext & Context,MCAsmBackend & MAB,MCCodeEmitter & CE,raw_pwrite_stream & OS)40 MCWinCOFFStreamer::MCWinCOFFStreamer(MCContext &Context, MCAsmBackend &MAB,
41 MCCodeEmitter &CE, raw_pwrite_stream &OS)
42 : MCObjectStreamer(Context, MAB, OS, &CE), CurSymbol(nullptr) {}
43
EmitInstToData(const MCInst & Inst,const MCSubtargetInfo & STI)44 void MCWinCOFFStreamer::EmitInstToData(const MCInst &Inst,
45 const MCSubtargetInfo &STI) {
46 MCDataFragment *DF = getOrCreateDataFragment();
47
48 SmallVector<MCFixup, 4> Fixups;
49 SmallString<256> Code;
50 raw_svector_ostream VecOS(Code);
51 getAssembler().getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
52
53 // Add the fixups and data.
54 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
55 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
56 DF->getFixups().push_back(Fixups[i]);
57 }
58
59 DF->getContents().append(Code.begin(), Code.end());
60 }
61
InitSections(bool NoExecStack)62 void MCWinCOFFStreamer::InitSections(bool NoExecStack) {
63 // FIXME: this is identical to the ELF one.
64 // This emulates the same behavior of GNU as. This makes it easier
65 // to compare the output as the major sections are in the same order.
66 SwitchSection(getContext().getObjectFileInfo()->getTextSection());
67 EmitCodeAlignment(4);
68
69 SwitchSection(getContext().getObjectFileInfo()->getDataSection());
70 EmitCodeAlignment(4);
71
72 SwitchSection(getContext().getObjectFileInfo()->getBSSSection());
73 EmitCodeAlignment(4);
74
75 SwitchSection(getContext().getObjectFileInfo()->getTextSection());
76 }
77
EmitLabel(MCSymbol * Symbol)78 void MCWinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
79 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
80 MCObjectStreamer::EmitLabel(Symbol);
81 }
82
EmitAssemblerFlag(MCAssemblerFlag Flag)83 void MCWinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
84 llvm_unreachable("not implemented");
85 }
86
EmitThumbFunc(MCSymbol * Func)87 void MCWinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
88 llvm_unreachable("not implemented");
89 }
90
EmitSymbolAttribute(MCSymbol * Symbol,MCSymbolAttr Attribute)91 bool MCWinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
92 MCSymbolAttr Attribute) {
93 assert(Symbol && "Symbol must be non-null!");
94 assert((!Symbol->isInSection() ||
95 Symbol->getSection().getVariant() == MCSection::SV_COFF) &&
96 "Got non-COFF section in the COFF backend!");
97
98 getAssembler().registerSymbol(*Symbol);
99
100 switch (Attribute) {
101 default: return false;
102 case MCSA_WeakReference:
103 case MCSA_Weak:
104 cast<MCSymbolCOFF>(Symbol)->setIsWeakExternal();
105 Symbol->setExternal(true);
106 break;
107 case MCSA_Global:
108 Symbol->setExternal(true);
109 break;
110 }
111
112 return true;
113 }
114
EmitSymbolDesc(MCSymbol * Symbol,unsigned DescValue)115 void MCWinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
116 llvm_unreachable("not implemented");
117 }
118
BeginCOFFSymbolDef(MCSymbol const * Symbol)119 void MCWinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) {
120 assert((!Symbol->isInSection() ||
121 Symbol->getSection().getVariant() == MCSection::SV_COFF) &&
122 "Got non-COFF section in the COFF backend!");
123
124 if (CurSymbol)
125 Error("starting a new symbol definition without completing the "
126 "previous one");
127 CurSymbol = Symbol;
128 }
129
EmitCOFFSymbolStorageClass(int StorageClass)130 void MCWinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
131 if (!CurSymbol) {
132 Error("storage class specified outside of symbol definition");
133 return;
134 }
135
136 if (StorageClass & ~COFF::SSC_Invalid) {
137 Error("storage class value '" + Twine(StorageClass) +
138 "' out of range");
139 return;
140 }
141
142 getAssembler().registerSymbol(*CurSymbol);
143 cast<MCSymbolCOFF>(CurSymbol)->setClass((uint16_t)StorageClass);
144 }
145
EmitCOFFSymbolType(int Type)146 void MCWinCOFFStreamer::EmitCOFFSymbolType(int Type) {
147 if (!CurSymbol) {
148 Error("symbol type specified outside of a symbol definition");
149 return;
150 }
151
152 if (Type & ~0xffff) {
153 Error("type value '" + Twine(Type) + "' out of range");
154 return;
155 }
156
157 getAssembler().registerSymbol(*CurSymbol);
158 cast<MCSymbolCOFF>(CurSymbol)->setType((uint16_t)Type);
159 }
160
EndCOFFSymbolDef()161 void MCWinCOFFStreamer::EndCOFFSymbolDef() {
162 if (!CurSymbol)
163 Error("ending symbol definition without starting one");
164 CurSymbol = nullptr;
165 }
166
EmitCOFFSafeSEH(MCSymbol const * Symbol)167 void MCWinCOFFStreamer::EmitCOFFSafeSEH(MCSymbol const *Symbol) {
168 // SafeSEH is a feature specific to 32-bit x86. It does not exist (and is
169 // unnecessary) on all platforms which use table-based exception dispatch.
170 if (getContext().getObjectFileInfo()->getTargetTriple().getArch() !=
171 Triple::x86)
172 return;
173
174 const MCSymbolCOFF *CSymbol = cast<MCSymbolCOFF>(Symbol);
175 if (CSymbol->isSafeSEH())
176 return;
177
178 MCSection *SXData = getContext().getObjectFileInfo()->getSXDataSection();
179 getAssembler().registerSection(*SXData);
180 if (SXData->getAlignment() < 4)
181 SXData->setAlignment(4);
182
183 new MCSafeSEHFragment(Symbol, SXData);
184
185 getAssembler().registerSymbol(*Symbol);
186 CSymbol->setIsSafeSEH();
187
188 // The Microsoft linker requires that the symbol type of a handler be
189 // function. Go ahead and oblige it here.
190 CSymbol->setType(COFF::IMAGE_SYM_DTYPE_FUNCTION
191 << COFF::SCT_COMPLEX_TYPE_SHIFT);
192 }
193
EmitCOFFSectionIndex(MCSymbol const * Symbol)194 void MCWinCOFFStreamer::EmitCOFFSectionIndex(MCSymbol const *Symbol) {
195 MCDataFragment *DF = getOrCreateDataFragment();
196 const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(Symbol, getContext());
197 MCFixup Fixup = MCFixup::create(DF->getContents().size(), SRE, FK_SecRel_2);
198 DF->getFixups().push_back(Fixup);
199 DF->getContents().resize(DF->getContents().size() + 2, 0);
200 }
201
EmitCOFFSecRel32(MCSymbol const * Symbol)202 void MCWinCOFFStreamer::EmitCOFFSecRel32(MCSymbol const *Symbol) {
203 MCDataFragment *DF = getOrCreateDataFragment();
204 const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(Symbol, getContext());
205 MCFixup Fixup = MCFixup::create(DF->getContents().size(), SRE, FK_SecRel_4);
206 DF->getFixups().push_back(Fixup);
207 DF->getContents().resize(DF->getContents().size() + 4, 0);
208 }
209
EmitCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)210 void MCWinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
211 unsigned ByteAlignment) {
212 assert((!Symbol->isInSection() ||
213 Symbol->getSection().getVariant() == MCSection::SV_COFF) &&
214 "Got non-COFF section in the COFF backend!");
215
216 const Triple &T = getContext().getObjectFileInfo()->getTargetTriple();
217 if (T.isKnownWindowsMSVCEnvironment()) {
218 if (ByteAlignment > 32)
219 report_fatal_error("alignment is limited to 32-bytes");
220
221 // Round size up to alignment so that we will honor the alignment request.
222 Size = std::max(Size, static_cast<uint64_t>(ByteAlignment));
223 }
224
225 getAssembler().registerSymbol(*Symbol);
226 Symbol->setExternal(true);
227 Symbol->setCommon(Size, ByteAlignment);
228
229 if (!T.isKnownWindowsMSVCEnvironment() && ByteAlignment > 1) {
230 SmallString<128> Directive;
231 raw_svector_ostream OS(Directive);
232 const MCObjectFileInfo *MFI = getContext().getObjectFileInfo();
233
234 OS << " -aligncomm:\"" << Symbol->getName() << "\","
235 << Log2_32_Ceil(ByteAlignment);
236
237 PushSection();
238 SwitchSection(MFI->getDrectveSection());
239 EmitBytes(Directive);
240 PopSection();
241 }
242 }
243
EmitLocalCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)244 void MCWinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
245 unsigned ByteAlignment) {
246 assert(!Symbol->isInSection() && "Symbol must not already have a section!");
247
248 MCSection *Section = getContext().getObjectFileInfo()->getBSSSection();
249 getAssembler().registerSection(*Section);
250 if (Section->getAlignment() < ByteAlignment)
251 Section->setAlignment(ByteAlignment);
252
253 getAssembler().registerSymbol(*Symbol);
254 Symbol->setExternal(false);
255
256 if (ByteAlignment != 1)
257 new MCAlignFragment(ByteAlignment, /*Value=*/0, /*ValueSize=*/0,
258 ByteAlignment, Section);
259
260 MCFillFragment *Fragment = new MCFillFragment(
261 /*Value=*/0, /*ValueSize=*/0, Size, Section);
262 Symbol->setFragment(Fragment);
263 }
264
EmitZerofill(MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)265 void MCWinCOFFStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
266 uint64_t Size, unsigned ByteAlignment) {
267 llvm_unreachable("not implemented");
268 }
269
EmitTBSSSymbol(MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)270 void MCWinCOFFStreamer::EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
271 uint64_t Size, unsigned ByteAlignment) {
272 llvm_unreachable("not implemented");
273 }
274
EmitFileDirective(StringRef Filename)275 void MCWinCOFFStreamer::EmitFileDirective(StringRef Filename) {
276 getAssembler().addFileName(Filename);
277 }
278
279 // TODO: Implement this if you want to emit .comment section in COFF obj files.
EmitIdent(StringRef IdentString)280 void MCWinCOFFStreamer::EmitIdent(StringRef IdentString) {
281 llvm_unreachable("not implemented");
282 }
283
EmitWinEHHandlerData()284 void MCWinCOFFStreamer::EmitWinEHHandlerData() {
285 llvm_unreachable("not implemented");
286 }
287
FinishImpl()288 void MCWinCOFFStreamer::FinishImpl() {
289 MCObjectStreamer::FinishImpl();
290 }
291
Error(const Twine & Msg) const292 void MCWinCOFFStreamer::Error(const Twine &Msg) const {
293 getContext().reportError(SMLoc(), Msg);
294 }
295 }
296
297