1 //===-- X86ELFObjectWriter.cpp - X86 ELF 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 #include "MCTargetDesc/X86FixupKinds.h"
11 #include "MCTargetDesc/X86MCTargetDesc.h"
12 #include "llvm/MC/MCAsmInfo.h"
13 #include "llvm/MC/MCContext.h"
14 #include "llvm/MC/MCELFObjectWriter.h"
15 #include "llvm/MC/MCExpr.h"
16 #include "llvm/MC/MCValue.h"
17 #include "llvm/Support/ELF.h"
18 #include "llvm/Support/ErrorHandling.h"
23 class X86ELFObjectWriter : public MCELFObjectTargetWriter {
25 X86ELFObjectWriter(bool IsELF64, uint8_t OSABI, uint16_t EMachine);
27 ~X86ELFObjectWriter() override;
30 unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
31 const MCFixup &Fixup, bool IsPCRel) const override;
35 X86ELFObjectWriter::X86ELFObjectWriter(bool IsELF64, uint8_t OSABI,
37 : MCELFObjectTargetWriter(IsELF64, OSABI, EMachine,
38 // Only i386 and IAMCU use Rel instead of RelA.
39 /*HasRelocationAddend*/
40 (EMachine != ELF::EM_386) &&
41 (EMachine != ELF::EM_IAMCU)) {}
43 X86ELFObjectWriter::~X86ELFObjectWriter()
46 enum X86_64RelType { RT64_64, RT64_32, RT64_32S, RT64_16, RT64_8 };
48 static X86_64RelType getType64(unsigned Kind,
49 MCSymbolRefExpr::VariantKind &Modifier,
53 llvm_unreachable("Unimplemented");
54 case X86::reloc_global_offset_table8:
55 Modifier = MCSymbolRefExpr::VK_GOT;
60 case X86::reloc_signed_4byte:
61 case X86::reloc_signed_4byte_relax:
62 if (Modifier == MCSymbolRefExpr::VK_None && !IsPCRel)
65 case X86::reloc_global_offset_table:
66 Modifier = MCSymbolRefExpr::VK_GOT;
71 case X86::reloc_riprel_4byte:
72 case X86::reloc_riprel_4byte_relax:
73 case X86::reloc_riprel_4byte_relax_rex:
74 case X86::reloc_riprel_4byte_movq_load:
85 static void checkIs32(MCContext &Ctx, SMLoc Loc, X86_64RelType Type) {
88 "32 bit reloc applied to a field with a different size");
91 static unsigned getRelocType64(MCContext &Ctx, SMLoc Loc,
92 MCSymbolRefExpr::VariantKind Modifier,
93 X86_64RelType Type, bool IsPCRel,
97 llvm_unreachable("Unimplemented");
98 case MCSymbolRefExpr::VK_None:
101 return IsPCRel ? ELF::R_X86_64_PC64 : ELF::R_X86_64_64;
103 return IsPCRel ? ELF::R_X86_64_PC32 : ELF::R_X86_64_32;
105 return ELF::R_X86_64_32S;
107 return IsPCRel ? ELF::R_X86_64_PC16 : ELF::R_X86_64_16;
109 return IsPCRel ? ELF::R_X86_64_PC8 : ELF::R_X86_64_8;
111 case MCSymbolRefExpr::VK_GOT:
114 return IsPCRel ? ELF::R_X86_64_GOTPC64 : ELF::R_X86_64_GOT64;
116 return IsPCRel ? ELF::R_X86_64_GOTPC32 : ELF::R_X86_64_GOT32;
120 llvm_unreachable("Unimplemented");
122 case MCSymbolRefExpr::VK_GOTOFF:
123 assert(Type == RT64_64);
125 return ELF::R_X86_64_GOTOFF64;
126 case MCSymbolRefExpr::VK_TPOFF:
130 return ELF::R_X86_64_TPOFF64;
132 return ELF::R_X86_64_TPOFF32;
136 llvm_unreachable("Unimplemented");
138 case MCSymbolRefExpr::VK_DTPOFF:
142 return ELF::R_X86_64_DTPOFF64;
144 return ELF::R_X86_64_DTPOFF32;
148 llvm_unreachable("Unimplemented");
150 case MCSymbolRefExpr::VK_SIZE:
154 return ELF::R_X86_64_SIZE64;
156 return ELF::R_X86_64_SIZE32;
160 llvm_unreachable("Unimplemented");
162 case MCSymbolRefExpr::VK_TLSCALL:
163 return ELF::R_X86_64_TLSDESC_CALL;
164 case MCSymbolRefExpr::VK_TLSDESC:
165 return ELF::R_X86_64_GOTPC32_TLSDESC;
166 case MCSymbolRefExpr::VK_TLSGD:
167 checkIs32(Ctx, Loc, Type);
168 return ELF::R_X86_64_TLSGD;
169 case MCSymbolRefExpr::VK_GOTTPOFF:
170 checkIs32(Ctx, Loc, Type);
171 return ELF::R_X86_64_GOTTPOFF;
172 case MCSymbolRefExpr::VK_TLSLD:
173 checkIs32(Ctx, Loc, Type);
174 return ELF::R_X86_64_TLSLD;
175 case MCSymbolRefExpr::VK_PLT:
176 checkIs32(Ctx, Loc, Type);
177 return ELF::R_X86_64_PLT32;
178 case MCSymbolRefExpr::VK_GOTPCREL:
179 checkIs32(Ctx, Loc, Type);
180 // Older versions of ld.bfd/ld.gold/lld
181 // do not support GOTPCRELX/REX_GOTPCRELX,
182 // and we want to keep back-compatibility.
183 if (!Ctx.getAsmInfo()->canRelaxRelocations())
184 return ELF::R_X86_64_GOTPCREL;
187 return ELF::R_X86_64_GOTPCREL;
188 case X86::reloc_riprel_4byte_relax:
189 return ELF::R_X86_64_GOTPCRELX;
190 case X86::reloc_riprel_4byte_relax_rex:
191 case X86::reloc_riprel_4byte_movq_load:
192 return ELF::R_X86_64_REX_GOTPCRELX;
197 enum X86_32RelType { RT32_32, RT32_16, RT32_8 };
199 static X86_32RelType getType32(X86_64RelType T) {
202 llvm_unreachable("Unimplemented");
211 llvm_unreachable("unexpected relocation type!");
214 static unsigned getRelocType32(MCContext &Ctx,
215 MCSymbolRefExpr::VariantKind Modifier,
216 X86_32RelType Type, bool IsPCRel,
220 llvm_unreachable("Unimplemented");
221 case MCSymbolRefExpr::VK_None:
224 return IsPCRel ? ELF::R_386_PC32 : ELF::R_386_32;
226 return IsPCRel ? ELF::R_386_PC16 : ELF::R_386_16;
228 return IsPCRel ? ELF::R_386_PC8 : ELF::R_386_8;
230 case MCSymbolRefExpr::VK_GOT:
231 assert(Type == RT32_32);
233 return ELF::R_386_GOTPC;
234 // Older versions of ld.bfd/ld.gold/lld do not support R_386_GOT32X and we
235 // want to maintain compatibility.
236 if (!Ctx.getAsmInfo()->canRelaxRelocations())
237 return ELF::R_386_GOT32;
239 return Kind == X86::reloc_signed_4byte_relax ? ELF::R_386_GOT32X
241 case MCSymbolRefExpr::VK_GOTOFF:
242 assert(Type == RT32_32);
244 return ELF::R_386_GOTOFF;
245 case MCSymbolRefExpr::VK_TPOFF:
246 assert(Type == RT32_32);
248 return ELF::R_386_TLS_LE_32;
249 case MCSymbolRefExpr::VK_DTPOFF:
250 assert(Type == RT32_32);
252 return ELF::R_386_TLS_LDO_32;
253 case MCSymbolRefExpr::VK_TLSGD:
254 assert(Type == RT32_32);
256 return ELF::R_386_TLS_GD;
257 case MCSymbolRefExpr::VK_GOTTPOFF:
258 assert(Type == RT32_32);
260 return ELF::R_386_TLS_IE_32;
261 case MCSymbolRefExpr::VK_PLT:
262 assert(Type == RT32_32);
263 return ELF::R_386_PLT32;
264 case MCSymbolRefExpr::VK_INDNTPOFF:
265 assert(Type == RT32_32);
267 return ELF::R_386_TLS_IE;
268 case MCSymbolRefExpr::VK_NTPOFF:
269 assert(Type == RT32_32);
271 return ELF::R_386_TLS_LE;
272 case MCSymbolRefExpr::VK_GOTNTPOFF:
273 assert(Type == RT32_32);
275 return ELF::R_386_TLS_GOTIE;
276 case MCSymbolRefExpr::VK_TLSLDM:
277 assert(Type == RT32_32);
279 return ELF::R_386_TLS_LDM;
283 unsigned X86ELFObjectWriter::getRelocType(MCContext &Ctx, const MCValue &Target,
284 const MCFixup &Fixup,
285 bool IsPCRel) const {
286 MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
287 unsigned Kind = Fixup.getKind();
288 X86_64RelType Type = getType64(Kind, Modifier, IsPCRel);
289 if (getEMachine() == ELF::EM_X86_64)
290 return getRelocType64(Ctx, Fixup.getLoc(), Modifier, Type, IsPCRel, Kind);
292 assert((getEMachine() == ELF::EM_386 || getEMachine() == ELF::EM_IAMCU) &&
293 "Unsupported ELF machine type.");
294 return getRelocType32(Ctx, Modifier, getType32(Type), IsPCRel, Kind);
297 MCObjectWriter *llvm::createX86ELFObjectWriter(raw_pwrite_stream &OS,
298 bool IsELF64, uint8_t OSABI,
300 MCELFObjectTargetWriter *MOTW =
301 new X86ELFObjectWriter(IsELF64, OSABI, EMachine);
302 return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/true);