| 1 | //===-- MipsELFObjectWriter.cpp - Mips ELF Writer -------------------------===// |
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | |
| 9 | #include "MCTargetDesc/MipsFixupKinds.h" |
| 10 | #include "MCTargetDesc/MipsMCAsmInfo.h" |
| 11 | #include "MCTargetDesc/MipsMCTargetDesc.h" |
| 12 | #include "llvm/ADT/STLExtras.h" |
| 13 | #include "llvm/BinaryFormat/ELF.h" |
| 14 | #include "llvm/MC/MCContext.h" |
| 15 | #include "llvm/MC/MCELFObjectWriter.h" |
| 16 | #include "llvm/MC/MCFixup.h" |
| 17 | #include "llvm/MC/MCObjectWriter.h" |
| 18 | #include "llvm/MC/MCSymbolELF.h" |
| 19 | #include "llvm/MC/MCValue.h" |
| 20 | #include "llvm/Support/Casting.h" |
| 21 | #include "llvm/Support/Compiler.h" |
| 22 | #include "llvm/Support/Debug.h" |
| 23 | #include "llvm/Support/ErrorHandling.h" |
| 24 | #include "llvm/Support/MathExtras.h" |
| 25 | #include "llvm/Support/raw_ostream.h" |
| 26 | #include <cassert> |
| 27 | #include <cstdint> |
| 28 | #include <iterator> |
| 29 | #include <list> |
| 30 | #include <utility> |
| 31 | |
| 32 | #define DEBUG_TYPE "mips-elf-object-writer" |
| 33 | |
| 34 | using namespace llvm; |
| 35 | |
| 36 | namespace { |
| 37 | |
| 38 | /// Holds additional information needed by the relocation ordering algorithm. |
| 39 | struct MipsRelocationEntry { |
| 40 | const ELFRelocationEntry R; ///< The relocation. |
| 41 | bool Matched = false; ///< Is this relocation part of a match. |
| 42 | |
| 43 | MipsRelocationEntry(const ELFRelocationEntry &R) : R(R) {} |
| 44 | }; |
| 45 | |
| 46 | class MipsELFObjectWriter : public MCELFObjectTargetWriter { |
| 47 | public: |
| 48 | MipsELFObjectWriter(uint8_t OSABI, bool HasRelocationAddend, bool Is64); |
| 49 | |
| 50 | ~MipsELFObjectWriter() override = default; |
| 51 | |
| 52 | unsigned getRelocType(const MCFixup &, const MCValue &, |
| 53 | bool IsPCRel) const override; |
| 54 | bool needsRelocateWithSymbol(const MCValue &, unsigned Type) const override; |
| 55 | void sortRelocs(std::vector<ELFRelocationEntry> &Relocs) override; |
| 56 | }; |
| 57 | |
| 58 | /// The possible results of the Predicate function used by find_best. |
| 59 | enum FindBestPredicateResult { |
| 60 | FindBest_NoMatch = 0, ///< The current element is not a match. |
| 61 | FindBest_Match, ///< The current element is a match but better ones are |
| 62 | /// possible. |
| 63 | FindBest_PerfectMatch, ///< The current element is an unbeatable match. |
| 64 | }; |
| 65 | |
| 66 | } // end anonymous namespace |
| 67 | |
| 68 | /// Copy elements in the range [First, Last) to d1 when the predicate is true or |
| 69 | /// d2 when the predicate is false. This is essentially both std::copy_if and |
| 70 | /// std::remove_copy_if combined into a single pass. |
| 71 | template <class InputIt, class OutputIt1, class OutputIt2, class UnaryPredicate> |
| 72 | static std::pair<OutputIt1, OutputIt2> copy_if_else(InputIt First, InputIt Last, |
| 73 | OutputIt1 d1, OutputIt2 d2, |
| 74 | UnaryPredicate Predicate) { |
| 75 | for (InputIt I = First; I != Last; ++I) { |
| 76 | if (Predicate(*I)) { |
| 77 | *d1 = *I; |
| 78 | d1++; |
| 79 | } else { |
| 80 | *d2 = *I; |
| 81 | d2++; |
| 82 | } |
| 83 | } |
| 84 | |
| 85 | return std::make_pair(d1, d2); |
| 86 | } |
| 87 | |
| 88 | /// Find the best match in the range [First, Last). |
| 89 | /// |
| 90 | /// An element matches when Predicate(X) returns FindBest_Match or |
| 91 | /// FindBest_PerfectMatch. A value of FindBest_PerfectMatch also terminates |
| 92 | /// the search. BetterThan(A, B) is a comparator that returns true when A is a |
| 93 | /// better match than B. The return value is the position of the best match. |
| 94 | /// |
| 95 | /// This is similar to std::find_if but finds the best of multiple possible |
| 96 | /// matches. |
| 97 | template <class InputIt, class UnaryPredicate, class Comparator> |
| 98 | static InputIt find_best(InputIt First, InputIt Last, UnaryPredicate Predicate, |
| 99 | Comparator BetterThan) { |
| 100 | InputIt Best = Last; |
| 101 | |
| 102 | for (InputIt I = First; I != Last; ++I) { |
| 103 | unsigned Matched = Predicate(*I); |
| 104 | if (Matched != FindBest_NoMatch) { |
| 105 | if (Best == Last || BetterThan(*I, *Best)) |
| 106 | Best = I; |
| 107 | } |
| 108 | if (Matched == FindBest_PerfectMatch) |
| 109 | break; |
| 110 | } |
| 111 | |
| 112 | return Best; |
| 113 | } |
| 114 | |
| 115 | /// Determine the low relocation that matches the given relocation. |
| 116 | /// If the relocation does not need a low relocation then the return value |
| 117 | /// is ELF::R_MIPS_NONE. |
| 118 | /// |
| 119 | /// The relocations that need a matching low part are |
| 120 | /// R_(MIPS|MICROMIPS|MIPS16)_HI16 for all symbols and |
| 121 | /// R_(MIPS|MICROMIPS|MIPS16)_GOT16 for local symbols only. |
| 122 | static unsigned getMatchingLoType(const ELFRelocationEntry &Reloc) { |
| 123 | unsigned Type = Reloc.Type; |
| 124 | if (Type == ELF::R_MIPS_HI16) |
| 125 | return ELF::R_MIPS_LO16; |
| 126 | if (Type == ELF::R_MICROMIPS_HI16) |
| 127 | return ELF::R_MICROMIPS_LO16; |
| 128 | if (Type == ELF::R_MIPS16_HI16) |
| 129 | return ELF::R_MIPS16_LO16; |
| 130 | |
| 131 | if (Reloc.Symbol && Reloc.Symbol->getBinding() != ELF::STB_LOCAL) |
| 132 | return ELF::R_MIPS_NONE; |
| 133 | |
| 134 | if (Type == ELF::R_MIPS_GOT16) |
| 135 | return ELF::R_MIPS_LO16; |
| 136 | if (Type == ELF::R_MICROMIPS_GOT16) |
| 137 | return ELF::R_MICROMIPS_LO16; |
| 138 | if (Type == ELF::R_MIPS16_GOT16) |
| 139 | return ELF::R_MIPS16_LO16; |
| 140 | |
| 141 | return ELF::R_MIPS_NONE; |
| 142 | } |
| 143 | |
| 144 | // Determine whether a relocation X is a low-part and matches the high-part R |
| 145 | // perfectly by symbol and addend. |
| 146 | static bool isMatchingReloc(unsigned MatchingType, const ELFRelocationEntry &R, |
| 147 | const ELFRelocationEntry &X) { |
| 148 | return X.Type == MatchingType && X.Symbol == R.Symbol && X.Addend == R.Addend; |
| 149 | } |
| 150 | |
| 151 | MipsELFObjectWriter::MipsELFObjectWriter(uint8_t OSABI, |
| 152 | bool HasRelocationAddend, bool Is64) |
| 153 | : MCELFObjectTargetWriter(Is64, OSABI, ELF::EM_MIPS, HasRelocationAddend) {} |
| 154 | |
| 155 | unsigned MipsELFObjectWriter::getRelocType(const MCFixup &Fixup, |
| 156 | const MCValue &Target, |
| 157 | bool IsPCRel) const { |
| 158 | // Determine the type of the relocation. |
| 159 | unsigned Kind = Fixup.getTargetKind(); |
| 160 | switch (Target.getSpecifier()) { |
| 161 | case Mips::S_DTPREL: |
| 162 | case Mips::S_DTPREL_HI: |
| 163 | case Mips::S_DTPREL_LO: |
| 164 | case Mips::S_TLSLDM: |
| 165 | case Mips::S_TLSGD: |
| 166 | case Mips::S_GOTTPREL: |
| 167 | case Mips::S_TPREL_HI: |
| 168 | case Mips::S_TPREL_LO: |
| 169 | if (auto *SA = Target.getAddSym()) |
| 170 | cast<MCSymbolELF>(Val: SA)->setType(ELF::STT_TLS); |
| 171 | break; |
| 172 | default: |
| 173 | break; |
| 174 | } |
| 175 | |
| 176 | switch (Kind) { |
| 177 | case FK_NONE: |
| 178 | return ELF::R_MIPS_NONE; |
| 179 | case FK_Data_1: |
| 180 | reportError(L: Fixup.getLoc(), Msg: "MIPS does not support one byte relocations" ); |
| 181 | return ELF::R_MIPS_NONE; |
| 182 | case Mips::fixup_Mips_16: |
| 183 | case FK_Data_2: |
| 184 | return IsPCRel ? ELF::R_MIPS_PC16 : ELF::R_MIPS_16; |
| 185 | case Mips::fixup_Mips_32: |
| 186 | case FK_Data_4: |
| 187 | return IsPCRel ? ELF::R_MIPS_PC32 : ELF::R_MIPS_32; |
| 188 | case Mips::fixup_Mips_64: |
| 189 | case FK_Data_8: |
| 190 | return IsPCRel |
| 191 | ? setRTypes(Value1: ELF::R_MIPS_PC32, Value2: ELF::R_MIPS_64, Value3: ELF::R_MIPS_NONE) |
| 192 | : (unsigned)ELF::R_MIPS_64; |
| 193 | } |
| 194 | |
| 195 | if (IsPCRel) { |
| 196 | switch (Kind) { |
| 197 | case Mips::fixup_Mips_Branch_PCRel: |
| 198 | case Mips::fixup_Mips_PC16: |
| 199 | return ELF::R_MIPS_PC16; |
| 200 | case Mips::fixup_MICROMIPS_PC7_S1: |
| 201 | return ELF::R_MICROMIPS_PC7_S1; |
| 202 | case Mips::fixup_MICROMIPS_PC10_S1: |
| 203 | return ELF::R_MICROMIPS_PC10_S1; |
| 204 | case Mips::fixup_MICROMIPS_PC16_S1: |
| 205 | return ELF::R_MICROMIPS_PC16_S1; |
| 206 | case Mips::fixup_MICROMIPS_PC26_S1: |
| 207 | return ELF::R_MICROMIPS_PC26_S1; |
| 208 | case Mips::fixup_MICROMIPS_PC19_S2: |
| 209 | return ELF::R_MICROMIPS_PC19_S2; |
| 210 | case Mips::fixup_MICROMIPS_PC18_S3: |
| 211 | return ELF::R_MICROMIPS_PC18_S3; |
| 212 | case Mips::fixup_MICROMIPS_PC21_S1: |
| 213 | return ELF::R_MICROMIPS_PC21_S1; |
| 214 | case Mips::fixup_MIPS_PC19_S2: |
| 215 | return ELF::R_MIPS_PC19_S2; |
| 216 | case Mips::fixup_MIPS_PC18_S3: |
| 217 | return ELF::R_MIPS_PC18_S3; |
| 218 | case Mips::fixup_MIPS_PC21_S2: |
| 219 | return ELF::R_MIPS_PC21_S2; |
| 220 | case Mips::fixup_MIPS_PC26_S2: |
| 221 | return ELF::R_MIPS_PC26_S2; |
| 222 | case Mips::fixup_MIPS_PCHI16: |
| 223 | return ELF::R_MIPS_PCHI16; |
| 224 | case Mips::fixup_MIPS_PCLO16: |
| 225 | return ELF::R_MIPS_PCLO16; |
| 226 | } |
| 227 | |
| 228 | llvm_unreachable("invalid PC-relative fixup kind!" ); |
| 229 | } |
| 230 | |
| 231 | switch (Kind) { |
| 232 | case Mips::fixup_Mips_DTPREL32: |
| 233 | return ELF::R_MIPS_TLS_DTPREL32; |
| 234 | case Mips::fixup_Mips_DTPREL64: |
| 235 | return ELF::R_MIPS_TLS_DTPREL64; |
| 236 | case Mips::fixup_Mips_TPREL32: |
| 237 | return ELF::R_MIPS_TLS_TPREL32; |
| 238 | case Mips::fixup_Mips_TPREL64: |
| 239 | return ELF::R_MIPS_TLS_TPREL64; |
| 240 | case Mips::fixup_Mips_GPREL32: |
| 241 | return setRTypes(Value1: ELF::R_MIPS_GPREL32, |
| 242 | Value2: is64Bit() ? ELF::R_MIPS_64 : ELF::R_MIPS_NONE, |
| 243 | Value3: ELF::R_MIPS_NONE); |
| 244 | case Mips::fixup_Mips_GPREL16: |
| 245 | return ELF::R_MIPS_GPREL16; |
| 246 | case Mips::fixup_Mips_26: |
| 247 | return ELF::R_MIPS_26; |
| 248 | case Mips::fixup_Mips_CALL16: |
| 249 | return ELF::R_MIPS_CALL16; |
| 250 | case Mips::fixup_Mips_GOT: |
| 251 | return ELF::R_MIPS_GOT16; |
| 252 | case Mips::fixup_Mips_HI16: |
| 253 | return ELF::R_MIPS_HI16; |
| 254 | case Mips::fixup_Mips_LO16: |
| 255 | return ELF::R_MIPS_LO16; |
| 256 | case Mips::fixup_Mips_TLSGD: |
| 257 | return ELF::R_MIPS_TLS_GD; |
| 258 | case Mips::fixup_Mips_GOTTPREL: |
| 259 | return ELF::R_MIPS_TLS_GOTTPREL; |
| 260 | case Mips::fixup_Mips_TPREL_HI: |
| 261 | return ELF::R_MIPS_TLS_TPREL_HI16; |
| 262 | case Mips::fixup_Mips_TPREL_LO: |
| 263 | return ELF::R_MIPS_TLS_TPREL_LO16; |
| 264 | case Mips::fixup_Mips_TLSLDM: |
| 265 | return ELF::R_MIPS_TLS_LDM; |
| 266 | case Mips::fixup_Mips_DTPREL_HI: |
| 267 | return ELF::R_MIPS_TLS_DTPREL_HI16; |
| 268 | case Mips::fixup_Mips_DTPREL_LO: |
| 269 | return ELF::R_MIPS_TLS_DTPREL_LO16; |
| 270 | case Mips::fixup_Mips_GOT_PAGE: |
| 271 | return ELF::R_MIPS_GOT_PAGE; |
| 272 | case Mips::fixup_Mips_GOT_OFST: |
| 273 | return ELF::R_MIPS_GOT_OFST; |
| 274 | case Mips::fixup_Mips_GOT_DISP: |
| 275 | return ELF::R_MIPS_GOT_DISP; |
| 276 | case Mips::fixup_Mips_GPOFF_HI: |
| 277 | return setRTypes(Value1: ELF::R_MIPS_GPREL16, Value2: ELF::R_MIPS_SUB, Value3: ELF::R_MIPS_HI16); |
| 278 | case Mips::fixup_MICROMIPS_GPOFF_HI: |
| 279 | return setRTypes(Value1: ELF::R_MICROMIPS_GPREL16, Value2: ELF::R_MICROMIPS_SUB, |
| 280 | Value3: ELF::R_MICROMIPS_HI16); |
| 281 | case Mips::fixup_Mips_GPOFF_LO: |
| 282 | return setRTypes(Value1: ELF::R_MIPS_GPREL16, Value2: ELF::R_MIPS_SUB, Value3: ELF::R_MIPS_LO16); |
| 283 | case Mips::fixup_MICROMIPS_GPOFF_LO: |
| 284 | return setRTypes(Value1: ELF::R_MICROMIPS_GPREL16, Value2: ELF::R_MICROMIPS_SUB, |
| 285 | Value3: ELF::R_MICROMIPS_LO16); |
| 286 | case Mips::fixup_Mips_HIGHER: |
| 287 | return ELF::R_MIPS_HIGHER; |
| 288 | case Mips::fixup_Mips_HIGHEST: |
| 289 | return ELF::R_MIPS_HIGHEST; |
| 290 | case Mips::fixup_Mips_SUB: |
| 291 | return ELF::R_MIPS_SUB; |
| 292 | case Mips::fixup_Mips_GOT_HI16: |
| 293 | return ELF::R_MIPS_GOT_HI16; |
| 294 | case Mips::fixup_Mips_GOT_LO16: |
| 295 | return ELF::R_MIPS_GOT_LO16; |
| 296 | case Mips::fixup_Mips_CALL_HI16: |
| 297 | return ELF::R_MIPS_CALL_HI16; |
| 298 | case Mips::fixup_Mips_CALL_LO16: |
| 299 | return ELF::R_MIPS_CALL_LO16; |
| 300 | case Mips::fixup_MICROMIPS_26_S1: |
| 301 | return ELF::R_MICROMIPS_26_S1; |
| 302 | case Mips::fixup_MICROMIPS_HI16: |
| 303 | return ELF::R_MICROMIPS_HI16; |
| 304 | case Mips::fixup_MICROMIPS_LO16: |
| 305 | return ELF::R_MICROMIPS_LO16; |
| 306 | case Mips::fixup_MICROMIPS_GOT16: |
| 307 | return ELF::R_MICROMIPS_GOT16; |
| 308 | case Mips::fixup_MICROMIPS_CALL16: |
| 309 | return ELF::R_MICROMIPS_CALL16; |
| 310 | case Mips::fixup_MICROMIPS_GOT_DISP: |
| 311 | return ELF::R_MICROMIPS_GOT_DISP; |
| 312 | case Mips::fixup_MICROMIPS_GOT_PAGE: |
| 313 | return ELF::R_MICROMIPS_GOT_PAGE; |
| 314 | case Mips::fixup_MICROMIPS_GOT_OFST: |
| 315 | return ELF::R_MICROMIPS_GOT_OFST; |
| 316 | case Mips::fixup_MICROMIPS_TLS_GD: |
| 317 | return ELF::R_MICROMIPS_TLS_GD; |
| 318 | case Mips::fixup_MICROMIPS_TLS_LDM: |
| 319 | return ELF::R_MICROMIPS_TLS_LDM; |
| 320 | case Mips::fixup_MICROMIPS_TLS_DTPREL_HI16: |
| 321 | return ELF::R_MICROMIPS_TLS_DTPREL_HI16; |
| 322 | case Mips::fixup_MICROMIPS_TLS_DTPREL_LO16: |
| 323 | return ELF::R_MICROMIPS_TLS_DTPREL_LO16; |
| 324 | case Mips::fixup_MICROMIPS_GOTTPREL: |
| 325 | return ELF::R_MICROMIPS_TLS_GOTTPREL; |
| 326 | case Mips::fixup_MICROMIPS_TLS_TPREL_HI16: |
| 327 | return ELF::R_MICROMIPS_TLS_TPREL_HI16; |
| 328 | case Mips::fixup_MICROMIPS_TLS_TPREL_LO16: |
| 329 | return ELF::R_MICROMIPS_TLS_TPREL_LO16; |
| 330 | case Mips::fixup_MICROMIPS_SUB: |
| 331 | return ELF::R_MICROMIPS_SUB; |
| 332 | case Mips::fixup_MICROMIPS_HIGHER: |
| 333 | return ELF::R_MICROMIPS_HIGHER; |
| 334 | case Mips::fixup_MICROMIPS_HIGHEST: |
| 335 | return ELF::R_MICROMIPS_HIGHEST; |
| 336 | case Mips::fixup_Mips_JALR: |
| 337 | return ELF::R_MIPS_JALR; |
| 338 | case Mips::fixup_MICROMIPS_JALR: |
| 339 | return ELF::R_MICROMIPS_JALR; |
| 340 | } |
| 341 | |
| 342 | reportError(L: Fixup.getLoc(), Msg: "unsupported relocation type" ); |
| 343 | return ELF::R_MIPS_NONE; |
| 344 | } |
| 345 | |
| 346 | /// Sort relocation table entries by offset except where another order is |
| 347 | /// required by the MIPS ABI. |
| 348 | /// |
| 349 | /// MIPS has a few relocations that have an AHL component in the expression used |
| 350 | /// to evaluate them. This AHL component is an addend with the same number of |
| 351 | /// bits as a symbol value but not all of our ABI's are able to supply a |
| 352 | /// sufficiently sized addend in a single relocation. |
| 353 | /// |
| 354 | /// The O32 ABI for example, uses REL relocations which store the addend in the |
| 355 | /// section data. All the relocations with AHL components affect 16-bit fields |
| 356 | /// so the addend for a single relocation is limited to 16-bit. This ABI |
| 357 | /// resolves the limitation by linking relocations (e.g. R_MIPS_HI16 and |
| 358 | /// R_MIPS_LO16) and distributing the addend between the linked relocations. The |
| 359 | /// ABI mandates that such relocations must be next to each other in a |
| 360 | /// particular order (e.g. R_MIPS_HI16 must be immediately followed by a |
| 361 | /// matching R_MIPS_LO16) but the rule is less strict in practice. |
| 362 | /// |
| 363 | /// The de facto standard is lenient in the following ways: |
| 364 | /// - 'Immediately following' does not refer to the next relocation entry but |
| 365 | /// the next matching relocation. |
| 366 | /// - There may be multiple high parts relocations for one low part relocation. |
| 367 | /// - There may be multiple low part relocations for one high part relocation. |
| 368 | /// - The AHL addend in each part does not have to be exactly equal as long as |
| 369 | /// the difference does not affect the carry bit from bit 15 into 16. This is |
| 370 | /// to allow, for example, the use of %lo(foo) and %lo(foo+4) when loading |
| 371 | /// both halves of a long long. |
| 372 | /// |
| 373 | /// See getMatchingLoType() for a description of which high part relocations |
| 374 | /// match which low part relocations. One particular thing to note is that |
| 375 | /// R_MIPS_GOT16 and similar only have AHL addends if they refer to local |
| 376 | /// symbols. |
| 377 | /// |
| 378 | /// It should also be noted that this function is not affected by whether |
| 379 | /// the symbol was kept or rewritten into a section-relative equivalent. We |
| 380 | /// always match using the expressions from the source. |
| 381 | void MipsELFObjectWriter::sortRelocs(std::vector<ELFRelocationEntry> &Relocs) { |
| 382 | // We do not need to sort the relocation table for RELA relocations which |
| 383 | // N32/N64 uses as the relocation addend contains the value we require, |
| 384 | // rather than it being split across a pair of relocations. |
| 385 | if (hasRelocationAddend()) |
| 386 | return; |
| 387 | |
| 388 | // Sort relocations by the address they are applied to. |
| 389 | llvm::sort(C&: Relocs, |
| 390 | Comp: [](const ELFRelocationEntry &A, const ELFRelocationEntry &B) { |
| 391 | return A.Offset < B.Offset; |
| 392 | }); |
| 393 | |
| 394 | // Place relocations in a list for reorder convenience. Hi16 contains the |
| 395 | // iterators of high-part relocations. |
| 396 | std::list<MipsRelocationEntry> Sorted; |
| 397 | SmallVector<std::list<MipsRelocationEntry>::iterator, 0> Hi16; |
| 398 | for (auto &R : Relocs) { |
| 399 | Sorted.push_back(x: R); |
| 400 | if (getMatchingLoType(Reloc: R) != ELF::R_MIPS_NONE) |
| 401 | Hi16.push_back(Elt: std::prev(x: Sorted.end())); |
| 402 | } |
| 403 | |
| 404 | for (auto I : Hi16) { |
| 405 | auto &R = I->R; |
| 406 | unsigned MatchingType = getMatchingLoType(Reloc: R); |
| 407 | // If the next relocation is a perfect match, continue; |
| 408 | if (std::next(x: I) != Sorted.end() && |
| 409 | isMatchingReloc(MatchingType, R, X: std::next(x: I)->R)) |
| 410 | continue; |
| 411 | // Otherwise, find the best matching low-part relocation with the following |
| 412 | // criteria. It must have the same symbol and its addend is no lower than |
| 413 | // that of the current high-part. |
| 414 | // |
| 415 | // (1) %lo with a smaller offset is preferred. |
| 416 | // (2) %lo with the same offset that is unmatched is preferred. |
| 417 | // (3) later %lo is preferred. |
| 418 | auto Best = Sorted.end(); |
| 419 | for (auto J = Sorted.begin(); J != Sorted.end(); ++J) { |
| 420 | auto &R1 = J->R; |
| 421 | if (R1.Type == MatchingType && R.Symbol == R1.Symbol && |
| 422 | R.Addend <= R1.Addend && |
| 423 | (Best == Sorted.end() || R1.Addend < Best->R.Addend || |
| 424 | (!Best->Matched && R1.Addend == Best->R.Addend))) |
| 425 | Best = J; |
| 426 | } |
| 427 | if (Best != Sorted.end() && R.Addend == Best->R.Addend) |
| 428 | Best->Matched = true; |
| 429 | |
| 430 | // Move the high-part before the low-part, or if not found, the end of the |
| 431 | // list. The unmatched high-part will lead to a linker warning/error. |
| 432 | Sorted.splice(position: Best, x&: Sorted, i: I); |
| 433 | } |
| 434 | |
| 435 | assert(Relocs.size() == Sorted.size() && "Some relocs were not consumed" ); |
| 436 | |
| 437 | // Overwrite the original vector with the sorted elements. |
| 438 | unsigned CopyTo = 0; |
| 439 | for (const auto &R : Sorted) |
| 440 | Relocs[CopyTo++] = R.R; |
| 441 | } |
| 442 | |
| 443 | bool MipsELFObjectWriter::needsRelocateWithSymbol(const MCValue &V, |
| 444 | unsigned Type) const { |
| 445 | // If it's a compound relocation for N64 then we need the relocation if any |
| 446 | // sub-relocation needs it. |
| 447 | if (!isUInt<8>(x: Type)) |
| 448 | return needsRelocateWithSymbol(V, Type: Type & 0xff) || |
| 449 | needsRelocateWithSymbol(V, Type: (Type >> 8) & 0xff) || |
| 450 | needsRelocateWithSymbol(V, Type: (Type >> 16) & 0xff); |
| 451 | |
| 452 | switch (Type) { |
| 453 | default: |
| 454 | errs() << Type << "\n" ; |
| 455 | llvm_unreachable("Unexpected relocation" ); |
| 456 | return true; |
| 457 | |
| 458 | // This relocation doesn't affect the section data. |
| 459 | case ELF::R_MIPS_NONE: |
| 460 | return false; |
| 461 | |
| 462 | // On REL ABI's (e.g. O32), these relocations form pairs. The pairing is done |
| 463 | // by the static linker by matching the symbol and offset. |
| 464 | // We only see one relocation at a time but it's still safe to relocate with |
| 465 | // the section so long as both relocations make the same decision. |
| 466 | // |
| 467 | // Some older linkers may require the symbol for particular cases. Such cases |
| 468 | // are not supported yet but can be added as required. |
| 469 | case ELF::R_MIPS_GOT16: |
| 470 | case ELF::R_MIPS16_GOT16: |
| 471 | case ELF::R_MICROMIPS_GOT16: |
| 472 | case ELF::R_MIPS_HIGHER: |
| 473 | case ELF::R_MIPS_HIGHEST: |
| 474 | case ELF::R_MIPS_HI16: |
| 475 | case ELF::R_MIPS16_HI16: |
| 476 | case ELF::R_MICROMIPS_HI16: |
| 477 | case ELF::R_MIPS_LO16: |
| 478 | case ELF::R_MIPS16_LO16: |
| 479 | case ELF::R_MICROMIPS_LO16: |
| 480 | // FIXME: It should be safe to return false for the STO_MIPS_MICROMIPS but |
| 481 | // we neglect to handle the adjustment to the LSB of the addend that |
| 482 | // it causes in applyFixup() and similar. |
| 483 | if (cast<MCSymbolELF>(Val: V.getAddSym())->getOther() & ELF::STO_MIPS_MICROMIPS) |
| 484 | return true; |
| 485 | return false; |
| 486 | |
| 487 | case ELF::R_MIPS_GOT_PAGE: |
| 488 | case ELF::R_MICROMIPS_GOT_PAGE: |
| 489 | case ELF::R_MIPS_GOT_OFST: |
| 490 | case ELF::R_MICROMIPS_GOT_OFST: |
| 491 | case ELF::R_MIPS_16: |
| 492 | case ELF::R_MIPS_32: |
| 493 | case ELF::R_MIPS_GPREL32: |
| 494 | if (cast<MCSymbolELF>(Val: V.getAddSym())->getOther() & ELF::STO_MIPS_MICROMIPS) |
| 495 | return true; |
| 496 | [[fallthrough]]; |
| 497 | case ELF::R_MIPS_26: |
| 498 | case ELF::R_MIPS_64: |
| 499 | case ELF::R_MIPS_GPREL16: |
| 500 | case ELF::R_MIPS_PC16: |
| 501 | case ELF::R_MIPS_SUB: |
| 502 | return false; |
| 503 | |
| 504 | // FIXME: Many of these relocations should probably return false but this |
| 505 | // hasn't been confirmed to be safe yet. |
| 506 | case ELF::R_MIPS_REL32: |
| 507 | case ELF::R_MIPS_LITERAL: |
| 508 | case ELF::R_MIPS_CALL16: |
| 509 | case ELF::R_MIPS_SHIFT5: |
| 510 | case ELF::R_MIPS_SHIFT6: |
| 511 | case ELF::R_MIPS_GOT_DISP: |
| 512 | case ELF::R_MIPS_GOT_HI16: |
| 513 | case ELF::R_MIPS_GOT_LO16: |
| 514 | case ELF::R_MIPS_INSERT_A: |
| 515 | case ELF::R_MIPS_INSERT_B: |
| 516 | case ELF::R_MIPS_DELETE: |
| 517 | case ELF::R_MIPS_CALL_HI16: |
| 518 | case ELF::R_MIPS_CALL_LO16: |
| 519 | case ELF::R_MIPS_SCN_DISP: |
| 520 | case ELF::R_MIPS_REL16: |
| 521 | case ELF::R_MIPS_ADD_IMMEDIATE: |
| 522 | case ELF::R_MIPS_PJUMP: |
| 523 | case ELF::R_MIPS_RELGOT: |
| 524 | case ELF::R_MIPS_JALR: |
| 525 | case ELF::R_MIPS_TLS_DTPMOD32: |
| 526 | case ELF::R_MIPS_TLS_DTPREL32: |
| 527 | case ELF::R_MIPS_TLS_DTPMOD64: |
| 528 | case ELF::R_MIPS_TLS_DTPREL64: |
| 529 | case ELF::R_MIPS_TLS_GD: |
| 530 | case ELF::R_MIPS_TLS_LDM: |
| 531 | case ELF::R_MIPS_TLS_DTPREL_HI16: |
| 532 | case ELF::R_MIPS_TLS_DTPREL_LO16: |
| 533 | case ELF::R_MIPS_TLS_GOTTPREL: |
| 534 | case ELF::R_MIPS_TLS_TPREL32: |
| 535 | case ELF::R_MIPS_TLS_TPREL64: |
| 536 | case ELF::R_MIPS_TLS_TPREL_HI16: |
| 537 | case ELF::R_MIPS_TLS_TPREL_LO16: |
| 538 | case ELF::R_MIPS_GLOB_DAT: |
| 539 | case ELF::R_MIPS_PC21_S2: |
| 540 | case ELF::R_MIPS_PC26_S2: |
| 541 | case ELF::R_MIPS_PC18_S3: |
| 542 | case ELF::R_MIPS_PC19_S2: |
| 543 | case ELF::R_MIPS_PCHI16: |
| 544 | case ELF::R_MIPS_PCLO16: |
| 545 | case ELF::R_MIPS_COPY: |
| 546 | case ELF::R_MIPS_JUMP_SLOT: |
| 547 | case ELF::R_MIPS_NUM: |
| 548 | case ELF::R_MIPS_PC32: |
| 549 | case ELF::R_MIPS_EH: |
| 550 | case ELF::R_MICROMIPS_26_S1: |
| 551 | case ELF::R_MICROMIPS_GPREL16: |
| 552 | case ELF::R_MICROMIPS_LITERAL: |
| 553 | case ELF::R_MICROMIPS_PC7_S1: |
| 554 | case ELF::R_MICROMIPS_PC10_S1: |
| 555 | case ELF::R_MICROMIPS_PC16_S1: |
| 556 | case ELF::R_MICROMIPS_CALL16: |
| 557 | case ELF::R_MICROMIPS_GOT_DISP: |
| 558 | case ELF::R_MICROMIPS_GOT_HI16: |
| 559 | case ELF::R_MICROMIPS_GOT_LO16: |
| 560 | case ELF::R_MICROMIPS_SUB: |
| 561 | case ELF::R_MICROMIPS_HIGHER: |
| 562 | case ELF::R_MICROMIPS_HIGHEST: |
| 563 | case ELF::R_MICROMIPS_CALL_HI16: |
| 564 | case ELF::R_MICROMIPS_CALL_LO16: |
| 565 | case ELF::R_MICROMIPS_SCN_DISP: |
| 566 | case ELF::R_MICROMIPS_JALR: |
| 567 | case ELF::R_MICROMIPS_HI0_LO16: |
| 568 | case ELF::R_MICROMIPS_TLS_GD: |
| 569 | case ELF::R_MICROMIPS_TLS_LDM: |
| 570 | case ELF::R_MICROMIPS_TLS_DTPREL_HI16: |
| 571 | case ELF::R_MICROMIPS_TLS_DTPREL_LO16: |
| 572 | case ELF::R_MICROMIPS_TLS_GOTTPREL: |
| 573 | case ELF::R_MICROMIPS_TLS_TPREL_HI16: |
| 574 | case ELF::R_MICROMIPS_TLS_TPREL_LO16: |
| 575 | case ELF::R_MICROMIPS_GPREL7_S2: |
| 576 | case ELF::R_MICROMIPS_PC23_S2: |
| 577 | case ELF::R_MICROMIPS_PC21_S1: |
| 578 | case ELF::R_MICROMIPS_PC26_S1: |
| 579 | case ELF::R_MICROMIPS_PC18_S3: |
| 580 | case ELF::R_MICROMIPS_PC19_S2: |
| 581 | return true; |
| 582 | |
| 583 | // FIXME: Many of these should probably return false but MIPS16 isn't |
| 584 | // supported by the integrated assembler. |
| 585 | case ELF::R_MIPS16_26: |
| 586 | case ELF::R_MIPS16_GPREL: |
| 587 | case ELF::R_MIPS16_CALL16: |
| 588 | case ELF::R_MIPS16_TLS_GD: |
| 589 | case ELF::R_MIPS16_TLS_LDM: |
| 590 | case ELF::R_MIPS16_TLS_DTPREL_HI16: |
| 591 | case ELF::R_MIPS16_TLS_DTPREL_LO16: |
| 592 | case ELF::R_MIPS16_TLS_GOTTPREL: |
| 593 | case ELF::R_MIPS16_TLS_TPREL_HI16: |
| 594 | case ELF::R_MIPS16_TLS_TPREL_LO16: |
| 595 | llvm_unreachable("Unsupported MIPS16 relocation" ); |
| 596 | return true; |
| 597 | } |
| 598 | } |
| 599 | |
| 600 | std::unique_ptr<MCObjectTargetWriter> |
| 601 | llvm::createMipsELFObjectWriter(const Triple &TT, bool IsN32) { |
| 602 | uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(OSType: TT.getOS()); |
| 603 | bool IsN64 = TT.isArch64Bit() && !IsN32; |
| 604 | bool HasRelocationAddend = TT.isArch64Bit(); |
| 605 | return std::make_unique<MipsELFObjectWriter>(args&: OSABI, args&: HasRelocationAddend, |
| 606 | args&: IsN64); |
| 607 | } |
| 608 | |