1 //===- lib/MC/ELFObjectWriter.h - ELF File Writer -------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements ELF object file writer information.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_MC_ELFOBJECTWRITER_H
15 #define LLVM_MC_ELFOBJECTWRITER_H
18 #include "llvm/ADT/OwningPtr.h"
19 #include "llvm/ADT/SmallPtrSet.h"
20 #include "llvm/ADT/SmallString.h"
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/MC/MCAssembler.h"
23 #include "llvm/MC/MCELFObjectWriter.h"
24 #include "llvm/MC/MCELFSymbolFlags.h"
25 #include "llvm/MC/MCObjectWriter.h"
26 #include "llvm/MC/MCExpr.h"
27 #include "llvm/MC/MCSymbol.h"
37 class ELFObjectWriter : public MCObjectWriter {
40 static bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind);
41 static bool RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant);
42 static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout);
43 static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data,
44 bool Used, bool Renamed);
45 static bool isLocal(const MCSymbolData &Data, bool isSignature,
47 static bool IsELFMetaDataSection(const MCSectionData &SD);
48 static uint64_t DataSectionSize(const MCSectionData &SD);
49 static uint64_t GetSectionFileSize(const MCAsmLayout &Layout,
50 const MCSectionData &SD);
51 static uint64_t GetSectionAddressSize(const MCAsmLayout &Layout,
52 const MCSectionData &SD);
54 void WriteDataSectionData(MCAssembler &Asm,
55 const MCAsmLayout &Layout,
56 const MCSectionELF &Section);
58 /*static bool isFixupKindX86RIPRel(unsigned Kind) {
59 return Kind == X86::reloc_riprel_4byte ||
60 Kind == X86::reloc_riprel_4byte_movq_load;
63 /// ELFSymbolData - Helper struct for containing some precomputed
64 /// information on symbols.
65 struct ELFSymbolData {
66 MCSymbolData *SymbolData;
68 uint32_t SectionIndex;
70 // Support lexicographic sorting.
71 bool operator<(const ELFSymbolData &RHS) const {
72 if (MCELF::GetType(*SymbolData) == ELF::STT_FILE)
74 if (MCELF::GetType(*RHS.SymbolData) == ELF::STT_FILE)
76 return SymbolData->getSymbol().getName() <
77 RHS.SymbolData->getSymbol().getName();
81 /// @name Relocation Data
84 struct ELFRelocationEntry {
85 // Make these big enough for both 32-bit and 64-bit
89 const MCSymbol *Symbol;
93 : r_offset(0), Index(0), Type(0), Symbol(0), r_addend(0) {}
95 ELFRelocationEntry(uint64_t RelocOffset, int Idx,
96 unsigned RelType, const MCSymbol *Sym,
98 : r_offset(RelocOffset), Index(Idx), Type(RelType),
99 Symbol(Sym), r_addend(Addend) {}
101 // Support lexicographic sorting.
102 bool operator<(const ELFRelocationEntry &RE) const {
103 return RE.r_offset < r_offset;
107 /// The target specific ELF writer instance.
108 llvm::OwningPtr<MCELFObjectTargetWriter> TargetObjectWriter;
110 SmallPtrSet<const MCSymbol *, 16> UsedInReloc;
111 SmallPtrSet<const MCSymbol *, 16> WeakrefUsedInReloc;
112 DenseMap<const MCSymbol *, const MCSymbol *> Renames;
114 llvm::DenseMap<const MCSectionData*,
115 std::vector<ELFRelocationEntry> > Relocations;
116 DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;
119 /// @name Symbol Table Data
122 SmallString<256> StringTable;
123 std::vector<ELFSymbolData> LocalSymbolData;
124 std::vector<ELFSymbolData> ExternalSymbolData;
125 std::vector<ELFSymbolData> UndefinedSymbolData;
131 bool NeedsSymtabShndx;
133 // This holds the symbol table index of the last local symbol.
134 unsigned LastLocalSymbolIndex;
135 // This holds the .strtab section index.
136 unsigned StringTableIndex;
137 // This holds the .symtab section index.
138 unsigned SymbolTableIndex;
140 unsigned ShstrtabIndex;
143 virtual const MCSymbol *SymbolToReloc(const MCAssembler &Asm,
144 const MCValue &Target,
146 const MCFixup &Fixup,
149 // For arch-specific emission of explicit reloc symbol
150 virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
151 const MCValue &Target,
153 const MCFixup &Fixup,
154 bool IsPCRel) const {
158 bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
159 bool hasRelocationAddend() const {
160 return TargetObjectWriter->hasRelocationAddend();
164 ELFObjectWriter(MCELFObjectTargetWriter *MOTW,
165 raw_ostream &_OS, bool IsLittleEndian)
166 : MCObjectWriter(_OS, IsLittleEndian),
167 TargetObjectWriter(MOTW),
168 NeedsGOT(false), NeedsSymtabShndx(false){
171 virtual ~ELFObjectWriter();
173 void WriteWord(uint64_t W) {
180 void StringLE16(char *buf, uint16_t Value) {
181 buf[0] = char(Value >> 0);
182 buf[1] = char(Value >> 8);
185 void StringLE32(char *buf, uint32_t Value) {
186 StringLE16(buf, uint16_t(Value >> 0));
187 StringLE16(buf + 2, uint16_t(Value >> 16));
190 void StringLE64(char *buf, uint64_t Value) {
191 StringLE32(buf, uint32_t(Value >> 0));
192 StringLE32(buf + 4, uint32_t(Value >> 32));
195 void StringBE16(char *buf ,uint16_t Value) {
196 buf[0] = char(Value >> 8);
197 buf[1] = char(Value >> 0);
200 void StringBE32(char *buf, uint32_t Value) {
201 StringBE16(buf, uint16_t(Value >> 16));
202 StringBE16(buf + 2, uint16_t(Value >> 0));
205 void StringBE64(char *buf, uint64_t Value) {
206 StringBE32(buf, uint32_t(Value >> 32));
207 StringBE32(buf + 4, uint32_t(Value >> 0));
210 void String8(MCDataFragment &F, uint8_t Value) {
213 F.getContents() += StringRef(buf, 1);
216 void String16(MCDataFragment &F, uint16_t Value) {
218 if (isLittleEndian())
219 StringLE16(buf, Value);
221 StringBE16(buf, Value);
222 F.getContents() += StringRef(buf, 2);
225 void String32(MCDataFragment &F, uint32_t Value) {
227 if (isLittleEndian())
228 StringLE32(buf, Value);
230 StringBE32(buf, Value);
231 F.getContents() += StringRef(buf, 4);
234 void String64(MCDataFragment &F, uint64_t Value) {
236 if (isLittleEndian())
237 StringLE64(buf, Value);
239 StringBE64(buf, Value);
240 F.getContents() += StringRef(buf, 8);
243 virtual void WriteHeader(uint64_t SectionDataSize,
244 unsigned NumberOfSections);
246 /// Default e_flags = 0
247 virtual void WriteEFlags() { Write32(0); }
249 virtual void WriteSymbolEntry(MCDataFragment *SymtabF,
250 MCDataFragment *ShndxF,
251 uint64_t name, uint8_t info,
252 uint64_t value, uint64_t size,
253 uint8_t other, uint32_t shndx,
256 virtual void WriteSymbol(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
258 const MCAsmLayout &Layout);
260 typedef DenseMap<const MCSectionELF*, uint32_t> SectionIndexMapTy;
261 virtual void WriteSymbolTable(MCDataFragment *SymtabF,
262 MCDataFragment *ShndxF,
263 const MCAssembler &Asm,
264 const MCAsmLayout &Layout,
265 const SectionIndexMapTy &SectionIndexMap);
267 virtual void RecordRelocation(const MCAssembler &Asm,
268 const MCAsmLayout &Layout,
269 const MCFragment *Fragment,
270 const MCFixup &Fixup,
271 MCValue Target, uint64_t &FixedValue);
273 virtual uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm,
276 // Map from a group section to the signature symbol
277 typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy;
278 // Map from a signature symbol to the group section
279 typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy;
280 // Map from a section to the section with the relocations
281 typedef DenseMap<const MCSectionELF*, const MCSectionELF*> RelMapTy;
282 // Map from a section to its offset
283 typedef DenseMap<const MCSectionELF*, uint64_t> SectionOffsetMapTy;
285 /// ComputeSymbolTable - Compute the symbol table data
287 /// \param StringTable [out] - The string table data.
288 /// \param StringIndexMap [out] - Map from symbol names to offsets in the
290 virtual void ComputeSymbolTable(MCAssembler &Asm,
291 const SectionIndexMapTy &SectionIndexMap,
292 RevGroupMapTy RevGroupMap,
293 unsigned NumRegularSections);
295 virtual void ComputeIndexMap(MCAssembler &Asm,
296 SectionIndexMapTy &SectionIndexMap,
297 const RelMapTy &RelMap);
299 void CreateRelocationSections(MCAssembler &Asm, MCAsmLayout &Layout,
302 void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
303 const RelMapTy &RelMap);
305 virtual void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout,
306 SectionIndexMapTy &SectionIndexMap,
307 const RelMapTy &RelMap);
309 // Create the sections that show up in the symbol table. Currently
310 // those are the .note.GNU-stack section and the group sections.
311 virtual void CreateIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout,
312 GroupMapTy &GroupMap,
313 RevGroupMapTy &RevGroupMap,
314 SectionIndexMapTy &SectionIndexMap,
315 const RelMapTy &RelMap);
317 virtual void ExecutePostLayoutBinding(MCAssembler &Asm,
318 const MCAsmLayout &Layout);
320 void WriteSectionHeader(MCAssembler &Asm, const GroupMapTy &GroupMap,
321 const MCAsmLayout &Layout,
322 const SectionIndexMapTy &SectionIndexMap,
323 const SectionOffsetMapTy &SectionOffsetMap);
325 void ComputeSectionOrder(MCAssembler &Asm,
326 std::vector<const MCSectionELF*> &Sections);
328 virtual void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags,
329 uint64_t Address, uint64_t Offset,
330 uint64_t Size, uint32_t Link, uint32_t Info,
331 uint64_t Alignment, uint64_t EntrySize);
333 virtual void WriteRelocationsFragment(const MCAssembler &Asm,
335 const MCSectionData *SD);
338 IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
339 const MCSymbolData &DataA,
340 const MCFragment &FB,
344 virtual void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
345 virtual void WriteSection(MCAssembler &Asm,
346 const SectionIndexMapTy &SectionIndexMap,
347 uint32_t GroupSymbolIndex,
348 uint64_t Offset, uint64_t Size, uint64_t Alignment,
349 const MCSectionELF &Section);
352 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
353 bool IsPCRel, bool IsRelocWithSymbol,
355 virtual void adjustFixupOffset(const MCFixup &Fixup,
356 uint64_t &RelocOffset) {}
359 //===- X86ELFObjectWriter -------------------------------------------===//
361 class X86ELFObjectWriter : public ELFObjectWriter {
363 X86ELFObjectWriter(MCELFObjectTargetWriter *MOTW,
365 bool IsLittleEndian);
367 virtual ~X86ELFObjectWriter();
369 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
370 bool IsPCRel, bool IsRelocWithSymbol,
375 //===- ARMELFObjectWriter -------------------------------------------===//
377 class ARMELFObjectWriter : public ELFObjectWriter {
379 // FIXME: MCAssembler can't yet return the Subtarget,
380 enum { DefaultEABIVersion = 0x05000000U };
382 ARMELFObjectWriter(MCELFObjectTargetWriter *MOTW,
384 bool IsLittleEndian);
386 virtual ~ARMELFObjectWriter();
388 virtual void WriteEFlags();
390 virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
391 const MCValue &Target,
393 const MCFixup &Fixup,
396 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
397 bool IsPCRel, bool IsRelocWithSymbol,
400 unsigned GetRelocTypeInner(const MCValue &Target,
401 const MCFixup &Fixup, bool IsPCRel) const;
405 //===- PPCELFObjectWriter -------------------------------------------===//
407 class PPCELFObjectWriter : public ELFObjectWriter {
409 PPCELFObjectWriter(MCELFObjectTargetWriter *MOTW,
411 bool IsLittleEndian);
413 virtual ~PPCELFObjectWriter();
415 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
416 bool IsPCRel, bool IsRelocWithSymbol,
418 virtual void adjustFixupOffset(const MCFixup &Fixup, uint64_t &RelocOffset);
421 //===- MBlazeELFObjectWriter -------------------------------------------===//
423 class MBlazeELFObjectWriter : public ELFObjectWriter {
425 MBlazeELFObjectWriter(MCELFObjectTargetWriter *MOTW,
427 bool IsLittleEndian);
429 virtual ~MBlazeELFObjectWriter();
431 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
432 bool IsPCRel, bool IsRelocWithSymbol,
436 //===- MipsELFObjectWriter -------------------------------------------===//
438 class MipsELFObjectWriter : public ELFObjectWriter {
440 MipsELFObjectWriter(MCELFObjectTargetWriter *MOTW,
442 bool IsLittleEndian);
444 virtual ~MipsELFObjectWriter();
445 virtual void WriteEFlags();
448 virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
449 const MCValue &Target,
451 const MCFixup &Fixup,
454 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
455 bool IsPCRel, bool IsRelocWithSymbol,