1 //===-- MipsAsmBackend.cpp - Mips Asm Backend ----------------------------===// 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 implements the MipsAsmBackend class. 11 // 12 //===----------------------------------------------------------------------===// 13 // 14 15 #include "MCTargetDesc/MipsFixupKinds.h" 16 #include "MCTargetDesc/MipsAsmBackend.h" 17 #include "MCTargetDesc/MipsMCTargetDesc.h" 18 #include "llvm/MC/MCAsmBackend.h" 19 #include "llvm/MC/MCAssembler.h" 20 #include "llvm/MC/MCContext.h" 21 #include "llvm/MC/MCDirectives.h" 22 #include "llvm/MC/MCELFObjectWriter.h" 23 #include "llvm/MC/MCFixupKindInfo.h" 24 #include "llvm/MC/MCObjectWriter.h" 25 #include "llvm/MC/MCSubtargetInfo.h" 26 #include "llvm/Support/ErrorHandling.h" 27 #include "llvm/Support/MathExtras.h" 28 #include "llvm/Support/raw_ostream.h" 29 30 using namespace llvm; 31 32 // Prepare value for the target space for it 33 static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value, 34 MCContext *Ctx = nullptr) { 35 36 unsigned Kind = Fixup.getKind(); 37 38 // Add/subtract and shift 39 switch (Kind) { 40 default: 41 return 0; 42 case FK_Data_2: 43 case FK_GPRel_4: 44 case FK_Data_4: 45 case FK_Data_8: 46 case Mips::fixup_Mips_LO16: 47 case Mips::fixup_Mips_GPREL16: 48 case Mips::fixup_Mips_GPOFF_HI: 49 case Mips::fixup_Mips_GPOFF_LO: 50 case Mips::fixup_Mips_GOT_PAGE: 51 case Mips::fixup_Mips_GOT_OFST: 52 case Mips::fixup_Mips_GOT_DISP: 53 case Mips::fixup_Mips_GOT_LO16: 54 case Mips::fixup_Mips_CALL_LO16: 55 case Mips::fixup_MICROMIPS_LO16: 56 case Mips::fixup_MICROMIPS_GOT_PAGE: 57 case Mips::fixup_MICROMIPS_GOT_OFST: 58 case Mips::fixup_MICROMIPS_GOT_DISP: 59 case Mips::fixup_MIPS_PCLO16: 60 break; 61 case Mips::fixup_Mips_PC16: 62 // So far we are only using this type for branches. 63 // For branches we start 1 instruction after the branch 64 // so the displacement will be one instruction size less. 65 Value -= 4; 66 // The displacement is then divided by 4 to give us an 18 bit 67 // address range. Forcing a signed division because Value can be negative. 68 Value = (int64_t)Value / 4; 69 // We now check if Value can be encoded as a 16-bit signed immediate. 70 if (!isIntN(16, Value) && Ctx) 71 Ctx->FatalError(Fixup.getLoc(), "out of range PC16 fixup"); 72 break; 73 case Mips::fixup_MIPS_PC19_S2: 74 // Forcing a signed division because Value can be negative. 75 Value = (int64_t)Value / 4; 76 // We now check if Value can be encoded as a 19-bit signed immediate. 77 if (!isIntN(19, Value) && Ctx) 78 Ctx->FatalError(Fixup.getLoc(), "out of range PC19 fixup"); 79 break; 80 case Mips::fixup_Mips_26: 81 // So far we are only using this type for jumps. 82 // The displacement is then divided by 4 to give us an 28 bit 83 // address range. 84 Value >>= 2; 85 break; 86 case Mips::fixup_Mips_HI16: 87 case Mips::fixup_Mips_GOT_Local: 88 case Mips::fixup_Mips_GOT_HI16: 89 case Mips::fixup_Mips_CALL_HI16: 90 case Mips::fixup_MICROMIPS_HI16: 91 case Mips::fixup_MIPS_PCHI16: 92 // Get the 2nd 16-bits. Also add 1 if bit 15 is 1. 93 Value = ((Value + 0x8000) >> 16) & 0xffff; 94 break; 95 case Mips::fixup_Mips_HIGHER: 96 // Get the 3rd 16-bits. 97 Value = ((Value + 0x80008000LL) >> 32) & 0xffff; 98 break; 99 case Mips::fixup_Mips_HIGHEST: 100 // Get the 4th 16-bits. 101 Value = ((Value + 0x800080008000LL) >> 48) & 0xffff; 102 break; 103 case Mips::fixup_MICROMIPS_26_S1: 104 Value >>= 1; 105 break; 106 case Mips::fixup_MICROMIPS_PC7_S1: 107 Value -= 4; 108 // Forcing a signed division because Value can be negative. 109 Value = (int64_t) Value / 2; 110 // We now check if Value can be encoded as a 7-bit signed immediate. 111 if (!isIntN(7, Value) && Ctx) 112 Ctx->FatalError(Fixup.getLoc(), "out of range PC7 fixup"); 113 break; 114 case Mips::fixup_MICROMIPS_PC16_S1: 115 Value -= 4; 116 // Forcing a signed division because Value can be negative. 117 Value = (int64_t)Value / 2; 118 // We now check if Value can be encoded as a 16-bit signed immediate. 119 if (!isIntN(16, Value) && Ctx) 120 Ctx->FatalError(Fixup.getLoc(), "out of range PC16 fixup"); 121 break; 122 case Mips::fixup_MIPS_PC18_S3: 123 // Forcing a signed division because Value can be negative. 124 Value = (int64_t)Value / 8; 125 // We now check if Value can be encoded as a 18-bit signed immediate. 126 if (!isIntN(18, Value) && Ctx) 127 Ctx->FatalError(Fixup.getLoc(), "out of range PC18 fixup"); 128 break; 129 case Mips::fixup_MIPS_PC21_S2: 130 Value -= 4; 131 // Forcing a signed division because Value can be negative. 132 Value = (int64_t) Value / 4; 133 // We now check if Value can be encoded as a 21-bit signed immediate. 134 if (!isIntN(21, Value) && Ctx) 135 Ctx->FatalError(Fixup.getLoc(), "out of range PC21 fixup"); 136 break; 137 case Mips::fixup_MIPS_PC26_S2: 138 Value -= 4; 139 // Forcing a signed division because Value can be negative. 140 Value = (int64_t) Value / 4; 141 // We now check if Value can be encoded as a 26-bit signed immediate. 142 if (!isIntN(26, Value) && Ctx) 143 Ctx->FatalError(Fixup.getLoc(), "out of range PC26 fixup"); 144 break; 145 } 146 147 return Value; 148 } 149 150 MCObjectWriter *MipsAsmBackend::createObjectWriter(raw_ostream &OS) const { 151 return createMipsELFObjectWriter(OS, 152 MCELFObjectTargetWriter::getOSABI(OSType), IsLittle, Is64Bit); 153 } 154 155 // Little-endian fixup data byte ordering: 156 // mips32r2: a | b | x | x 157 // microMIPS: x | x | a | b 158 159 static bool needsMMLEByteOrder(unsigned Kind) { 160 return Kind >= Mips::fixup_MICROMIPS_26_S1 && 161 Kind < Mips::LastTargetFixupKind; 162 } 163 164 // Calculate index for microMIPS specific little endian byte order 165 static unsigned calculateMMLEIndex(unsigned i) { 166 assert(i <= 3 && "Index out of range!"); 167 168 return (1 - i / 2) * 2 + i % 2; 169 } 170 171 /// ApplyFixup - Apply the \p Value for given \p Fixup into the provided 172 /// data fragment, at the offset specified by the fixup and following the 173 /// fixup kind as appropriate. 174 void MipsAsmBackend::applyFixup(const MCFixup &Fixup, char *Data, 175 unsigned DataSize, uint64_t Value, 176 bool IsPCRel) const { 177 MCFixupKind Kind = Fixup.getKind(); 178 Value = adjustFixupValue(Fixup, Value); 179 180 if (!Value) 181 return; // Doesn't change encoding. 182 183 // Where do we start in the object 184 unsigned Offset = Fixup.getOffset(); 185 // Number of bytes we need to fixup 186 unsigned NumBytes = (getFixupKindInfo(Kind).TargetSize + 7) / 8; 187 // Used to point to big endian bytes 188 unsigned FullSize; 189 190 switch ((unsigned)Kind) { 191 case FK_Data_2: 192 case Mips::fixup_Mips_16: 193 FullSize = 2; 194 break; 195 case FK_Data_8: 196 case Mips::fixup_Mips_64: 197 FullSize = 8; 198 break; 199 case FK_Data_4: 200 default: 201 FullSize = 4; 202 break; 203 } 204 205 // Grab current value, if any, from bits. 206 uint64_t CurVal = 0; 207 208 bool microMipsLEByteOrder = needsMMLEByteOrder((unsigned) Kind); 209 210 for (unsigned i = 0; i != NumBytes; ++i) { 211 unsigned Idx = IsLittle ? (microMipsLEByteOrder ? calculateMMLEIndex(i) 212 : i) 213 : (FullSize - 1 - i); 214 CurVal |= (uint64_t)((uint8_t)Data[Offset + Idx]) << (i*8); 215 } 216 217 uint64_t Mask = ((uint64_t)(-1) >> 218 (64 - getFixupKindInfo(Kind).TargetSize)); 219 CurVal |= Value & Mask; 220 221 // Write out the fixed up bytes back to the code/data bits. 222 for (unsigned i = 0; i != NumBytes; ++i) { 223 unsigned Idx = IsLittle ? (microMipsLEByteOrder ? calculateMMLEIndex(i) 224 : i) 225 : (FullSize - 1 - i); 226 Data[Offset + Idx] = (uint8_t)((CurVal >> (i*8)) & 0xff); 227 } 228 } 229 230 const MCFixupKindInfo &MipsAsmBackend:: 231 getFixupKindInfo(MCFixupKind Kind) const { 232 const static MCFixupKindInfo LittleEndianInfos[Mips::NumTargetFixupKinds] = { 233 // This table *must* be in same the order of fixup_* kinds in 234 // MipsFixupKinds.h. 235 // 236 // name offset bits flags 237 { "fixup_Mips_16", 0, 16, 0 }, 238 { "fixup_Mips_32", 0, 32, 0 }, 239 { "fixup_Mips_REL32", 0, 32, 0 }, 240 { "fixup_Mips_26", 0, 26, 0 }, 241 { "fixup_Mips_HI16", 0, 16, 0 }, 242 { "fixup_Mips_LO16", 0, 16, 0 }, 243 { "fixup_Mips_GPREL16", 0, 16, 0 }, 244 { "fixup_Mips_LITERAL", 0, 16, 0 }, 245 { "fixup_Mips_GOT_Global", 0, 16, 0 }, 246 { "fixup_Mips_GOT_Local", 0, 16, 0 }, 247 { "fixup_Mips_PC16", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 248 { "fixup_Mips_CALL16", 0, 16, 0 }, 249 { "fixup_Mips_GPREL32", 0, 32, 0 }, 250 { "fixup_Mips_SHIFT5", 6, 5, 0 }, 251 { "fixup_Mips_SHIFT6", 6, 5, 0 }, 252 { "fixup_Mips_64", 0, 64, 0 }, 253 { "fixup_Mips_TLSGD", 0, 16, 0 }, 254 { "fixup_Mips_GOTTPREL", 0, 16, 0 }, 255 { "fixup_Mips_TPREL_HI", 0, 16, 0 }, 256 { "fixup_Mips_TPREL_LO", 0, 16, 0 }, 257 { "fixup_Mips_TLSLDM", 0, 16, 0 }, 258 { "fixup_Mips_DTPREL_HI", 0, 16, 0 }, 259 { "fixup_Mips_DTPREL_LO", 0, 16, 0 }, 260 { "fixup_Mips_Branch_PCRel", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 261 { "fixup_Mips_GPOFF_HI", 0, 16, 0 }, 262 { "fixup_Mips_GPOFF_LO", 0, 16, 0 }, 263 { "fixup_Mips_GOT_PAGE", 0, 16, 0 }, 264 { "fixup_Mips_GOT_OFST", 0, 16, 0 }, 265 { "fixup_Mips_GOT_DISP", 0, 16, 0 }, 266 { "fixup_Mips_HIGHER", 0, 16, 0 }, 267 { "fixup_Mips_HIGHEST", 0, 16, 0 }, 268 { "fixup_Mips_GOT_HI16", 0, 16, 0 }, 269 { "fixup_Mips_GOT_LO16", 0, 16, 0 }, 270 { "fixup_Mips_CALL_HI16", 0, 16, 0 }, 271 { "fixup_Mips_CALL_LO16", 0, 16, 0 }, 272 { "fixup_Mips_PC18_S3", 0, 18, MCFixupKindInfo::FKF_IsPCRel }, 273 { "fixup_MIPS_PC19_S2", 0, 19, MCFixupKindInfo::FKF_IsPCRel }, 274 { "fixup_MIPS_PC21_S2", 0, 21, MCFixupKindInfo::FKF_IsPCRel }, 275 { "fixup_MIPS_PC26_S2", 0, 26, MCFixupKindInfo::FKF_IsPCRel }, 276 { "fixup_MIPS_PCHI16", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 277 { "fixup_MIPS_PCLO16", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 278 { "fixup_MICROMIPS_26_S1", 0, 26, 0 }, 279 { "fixup_MICROMIPS_HI16", 0, 16, 0 }, 280 { "fixup_MICROMIPS_LO16", 0, 16, 0 }, 281 { "fixup_MICROMIPS_GOT16", 0, 16, 0 }, 282 { "fixup_MICROMIPS_PC7_S1", 0, 7, MCFixupKindInfo::FKF_IsPCRel }, 283 { "fixup_MICROMIPS_PC16_S1", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 284 { "fixup_MICROMIPS_CALL16", 0, 16, 0 }, 285 { "fixup_MICROMIPS_GOT_DISP", 0, 16, 0 }, 286 { "fixup_MICROMIPS_GOT_PAGE", 0, 16, 0 }, 287 { "fixup_MICROMIPS_GOT_OFST", 0, 16, 0 }, 288 { "fixup_MICROMIPS_TLS_GD", 0, 16, 0 }, 289 { "fixup_MICROMIPS_TLS_LDM", 0, 16, 0 }, 290 { "fixup_MICROMIPS_TLS_DTPREL_HI16", 0, 16, 0 }, 291 { "fixup_MICROMIPS_TLS_DTPREL_LO16", 0, 16, 0 }, 292 { "fixup_MICROMIPS_TLS_TPREL_HI16", 0, 16, 0 }, 293 { "fixup_MICROMIPS_TLS_TPREL_LO16", 0, 16, 0 } 294 }; 295 296 const static MCFixupKindInfo BigEndianInfos[Mips::NumTargetFixupKinds] = { 297 // This table *must* be in same the order of fixup_* kinds in 298 // MipsFixupKinds.h. 299 // 300 // name offset bits flags 301 { "fixup_Mips_16", 16, 16, 0 }, 302 { "fixup_Mips_32", 0, 32, 0 }, 303 { "fixup_Mips_REL32", 0, 32, 0 }, 304 { "fixup_Mips_26", 6, 26, 0 }, 305 { "fixup_Mips_HI16", 16, 16, 0 }, 306 { "fixup_Mips_LO16", 16, 16, 0 }, 307 { "fixup_Mips_GPREL16", 16, 16, 0 }, 308 { "fixup_Mips_LITERAL", 16, 16, 0 }, 309 { "fixup_Mips_GOT_Global", 16, 16, 0 }, 310 { "fixup_Mips_GOT_Local", 16, 16, 0 }, 311 { "fixup_Mips_PC16", 16, 16, MCFixupKindInfo::FKF_IsPCRel }, 312 { "fixup_Mips_CALL16", 16, 16, 0 }, 313 { "fixup_Mips_GPREL32", 0, 32, 0 }, 314 { "fixup_Mips_SHIFT5", 21, 5, 0 }, 315 { "fixup_Mips_SHIFT6", 21, 5, 0 }, 316 { "fixup_Mips_64", 0, 64, 0 }, 317 { "fixup_Mips_TLSGD", 16, 16, 0 }, 318 { "fixup_Mips_GOTTPREL", 16, 16, 0 }, 319 { "fixup_Mips_TPREL_HI", 16, 16, 0 }, 320 { "fixup_Mips_TPREL_LO", 16, 16, 0 }, 321 { "fixup_Mips_TLSLDM", 16, 16, 0 }, 322 { "fixup_Mips_DTPREL_HI", 16, 16, 0 }, 323 { "fixup_Mips_DTPREL_LO", 16, 16, 0 }, 324 { "fixup_Mips_Branch_PCRel",16, 16, MCFixupKindInfo::FKF_IsPCRel }, 325 { "fixup_Mips_GPOFF_HI", 16, 16, 0 }, 326 { "fixup_Mips_GPOFF_LO", 16, 16, 0 }, 327 { "fixup_Mips_GOT_PAGE", 16, 16, 0 }, 328 { "fixup_Mips_GOT_OFST", 16, 16, 0 }, 329 { "fixup_Mips_GOT_DISP", 16, 16, 0 }, 330 { "fixup_Mips_HIGHER", 16, 16, 0 }, 331 { "fixup_Mips_HIGHEST", 16, 16, 0 }, 332 { "fixup_Mips_GOT_HI16", 16, 16, 0 }, 333 { "fixup_Mips_GOT_LO16", 16, 16, 0 }, 334 { "fixup_Mips_CALL_HI16", 16, 16, 0 }, 335 { "fixup_Mips_CALL_LO16", 16, 16, 0 }, 336 { "fixup_Mips_PC18_S3", 14, 18, MCFixupKindInfo::FKF_IsPCRel }, 337 { "fixup_MIPS_PC19_S2", 13, 19, MCFixupKindInfo::FKF_IsPCRel }, 338 { "fixup_MIPS_PC21_S2", 11, 21, MCFixupKindInfo::FKF_IsPCRel }, 339 { "fixup_MIPS_PC26_S2", 6, 26, MCFixupKindInfo::FKF_IsPCRel }, 340 { "fixup_MIPS_PCHI16", 16, 16, MCFixupKindInfo::FKF_IsPCRel }, 341 { "fixup_MIPS_PCLO16", 16, 16, MCFixupKindInfo::FKF_IsPCRel }, 342 { "fixup_MICROMIPS_26_S1", 6, 26, 0 }, 343 { "fixup_MICROMIPS_HI16", 16, 16, 0 }, 344 { "fixup_MICROMIPS_LO16", 16, 16, 0 }, 345 { "fixup_MICROMIPS_GOT16", 16, 16, 0 }, 346 { "fixup_MICROMIPS_PC7_S1", 9, 7, MCFixupKindInfo::FKF_IsPCRel }, 347 { "fixup_MICROMIPS_PC16_S1",16, 16, MCFixupKindInfo::FKF_IsPCRel }, 348 { "fixup_MICROMIPS_CALL16", 16, 16, 0 }, 349 { "fixup_MICROMIPS_GOT_DISP", 16, 16, 0 }, 350 { "fixup_MICROMIPS_GOT_PAGE", 16, 16, 0 }, 351 { "fixup_MICROMIPS_GOT_OFST", 16, 16, 0 }, 352 { "fixup_MICROMIPS_TLS_GD", 16, 16, 0 }, 353 { "fixup_MICROMIPS_TLS_LDM", 16, 16, 0 }, 354 { "fixup_MICROMIPS_TLS_DTPREL_HI16", 16, 16, 0 }, 355 { "fixup_MICROMIPS_TLS_DTPREL_LO16", 16, 16, 0 }, 356 { "fixup_MICROMIPS_TLS_TPREL_HI16", 16, 16, 0 }, 357 { "fixup_MICROMIPS_TLS_TPREL_LO16", 16, 16, 0 } 358 }; 359 360 if (Kind < FirstTargetFixupKind) 361 return MCAsmBackend::getFixupKindInfo(Kind); 362 363 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && 364 "Invalid kind!"); 365 366 if (IsLittle) 367 return LittleEndianInfos[Kind - FirstTargetFixupKind]; 368 return BigEndianInfos[Kind - FirstTargetFixupKind]; 369 } 370 371 /// WriteNopData - Write an (optimal) nop sequence of Count bytes 372 /// to the given output. If the target cannot generate such a sequence, 373 /// it should return an error. 374 /// 375 /// \return - True on success. 376 bool MipsAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const { 377 // Check for a less than instruction size number of bytes 378 // FIXME: 16 bit instructions are not handled yet here. 379 // We shouldn't be using a hard coded number for instruction size. 380 381 // If the count is not 4-byte aligned, we must be writing data into the text 382 // section (otherwise we have unaligned instructions, and thus have far 383 // bigger problems), so just write zeros instead. 384 for (uint64_t i = 0, e = Count % 4; i != e; ++i) 385 OW->Write8(0); 386 387 uint64_t NumNops = Count / 4; 388 for (uint64_t i = 0; i != NumNops; ++i) 389 OW->Write32(0); 390 return true; 391 } 392 393 /// processFixupValue - Target hook to process the literal value of a fixup 394 /// if necessary. 395 void MipsAsmBackend::processFixupValue(const MCAssembler &Asm, 396 const MCAsmLayout &Layout, 397 const MCFixup &Fixup, 398 const MCFragment *DF, 399 const MCValue &Target, 400 uint64_t &Value, 401 bool &IsResolved) { 402 // At this point we'll ignore the value returned by adjustFixupValue as 403 // we are only checking if the fixup can be applied correctly. We have 404 // access to MCContext from here which allows us to report a fatal error 405 // with *possibly* a source code location. 406 (void)adjustFixupValue(Fixup, Value, &Asm.getContext()); 407 } 408 409 // MCAsmBackend 410 MCAsmBackend *llvm::createMipsAsmBackendEL32(const Target &T, 411 const MCRegisterInfo &MRI, 412 StringRef TT, 413 StringRef CPU) { 414 return new MipsAsmBackend(T, Triple(TT).getOS(), 415 /*IsLittle*/true, /*Is64Bit*/false); 416 } 417 418 MCAsmBackend *llvm::createMipsAsmBackendEB32(const Target &T, 419 const MCRegisterInfo &MRI, 420 StringRef TT, 421 StringRef CPU) { 422 return new MipsAsmBackend(T, Triple(TT).getOS(), 423 /*IsLittle*/false, /*Is64Bit*/false); 424 } 425 426 MCAsmBackend *llvm::createMipsAsmBackendEL64(const Target &T, 427 const MCRegisterInfo &MRI, 428 StringRef TT, 429 StringRef CPU) { 430 return new MipsAsmBackend(T, Triple(TT).getOS(), 431 /*IsLittle*/true, /*Is64Bit*/true); 432 } 433 434 MCAsmBackend *llvm::createMipsAsmBackendEB64(const Target &T, 435 const MCRegisterInfo &MRI, 436 StringRef TT, 437 StringRef CPU) { 438 return new MipsAsmBackend(T, Triple(TT).getOS(), 439 /*IsLittle*/false, /*Is64Bit*/true); 440 } 441