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 30using namespace llvm; 31 32// Prepare value for the target space for it 33static 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_PC16_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 16-bit signed immediate. 111 if (!isIntN(16, Value) && Ctx) 112 Ctx->FatalError(Fixup.getLoc(), "out of range PC16 fixup"); 113 break; 114 case Mips::fixup_MIPS_PC18_S3: 115 // Forcing a signed division because Value can be negative. 116 Value = (int64_t)Value / 8; 117 // We now check if Value can be encoded as a 18-bit signed immediate. 118 if (!isIntN(18, Value) && Ctx) 119 Ctx->FatalError(Fixup.getLoc(), "out of range PC18 fixup"); 120 break; 121 case Mips::fixup_MIPS_PC21_S2: 122 Value -= 4; 123 // Forcing a signed division because Value can be negative. 124 Value = (int64_t) Value / 4; 125 // We now check if Value can be encoded as a 21-bit signed immediate. 126 if (!isIntN(21, Value) && Ctx) 127 Ctx->FatalError(Fixup.getLoc(), "out of range PC21 fixup"); 128 break; 129 case Mips::fixup_MIPS_PC26_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 26-bit signed immediate. 134 if (!isIntN(26, Value) && Ctx) 135 Ctx->FatalError(Fixup.getLoc(), "out of range PC26 fixup"); 136 break; 137 } 138 139 return Value; 140} 141 142MCObjectWriter *MipsAsmBackend::createObjectWriter(raw_ostream &OS) const { 143 return createMipsELFObjectWriter(OS, 144 MCELFObjectTargetWriter::getOSABI(OSType), IsLittle, Is64Bit); 145} 146 147// Little-endian fixup data byte ordering: 148// mips32r2: a | b | x | x 149// microMIPS: x | x | a | b 150 151static bool needsMMLEByteOrder(unsigned Kind) { 152 return Kind >= Mips::fixup_MICROMIPS_26_S1 && 153 Kind < Mips::LastTargetFixupKind; 154} 155 156// Calculate index for microMIPS specific little endian byte order 157static unsigned calculateMMLEIndex(unsigned i) { 158 assert(i <= 3 && "Index out of range!"); 159 160 return (1 - i / 2) * 2 + i % 2; 161} 162 163/// ApplyFixup - Apply the \p Value for given \p Fixup into the provided 164/// data fragment, at the offset specified by the fixup and following the 165/// fixup kind as appropriate. 166void MipsAsmBackend::applyFixup(const MCFixup &Fixup, char *Data, 167 unsigned DataSize, uint64_t Value, 168 bool IsPCRel) const { 169 MCFixupKind Kind = Fixup.getKind(); 170 Value = adjustFixupValue(Fixup, Value); 171 172 if (!Value) 173 return; // Doesn't change encoding. 174 175 // Where do we start in the object 176 unsigned Offset = Fixup.getOffset(); 177 // Number of bytes we need to fixup 178 unsigned NumBytes = (getFixupKindInfo(Kind).TargetSize + 7) / 8; 179 // Used to point to big endian bytes 180 unsigned FullSize; 181 182 switch ((unsigned)Kind) { 183 case FK_Data_2: 184 case Mips::fixup_Mips_16: 185 FullSize = 2; 186 break; 187 case FK_Data_8: 188 case Mips::fixup_Mips_64: 189 FullSize = 8; 190 break; 191 case FK_Data_4: 192 default: 193 FullSize = 4; 194 break; 195 } 196 197 // Grab current value, if any, from bits. 198 uint64_t CurVal = 0; 199 200 bool microMipsLEByteOrder = needsMMLEByteOrder((unsigned) Kind); 201 202 for (unsigned i = 0; i != NumBytes; ++i) { 203 unsigned Idx = IsLittle ? (microMipsLEByteOrder ? calculateMMLEIndex(i) 204 : i) 205 : (FullSize - 1 - i); 206 CurVal |= (uint64_t)((uint8_t)Data[Offset + Idx]) << (i*8); 207 } 208 209 uint64_t Mask = ((uint64_t)(-1) >> 210 (64 - getFixupKindInfo(Kind).TargetSize)); 211 CurVal |= Value & Mask; 212 213 // Write out the fixed up bytes back to the code/data bits. 214 for (unsigned i = 0; i != NumBytes; ++i) { 215 unsigned Idx = IsLittle ? (microMipsLEByteOrder ? calculateMMLEIndex(i) 216 : i) 217 : (FullSize - 1 - i); 218 Data[Offset + Idx] = (uint8_t)((CurVal >> (i*8)) & 0xff); 219 } 220} 221 222const MCFixupKindInfo &MipsAsmBackend:: 223getFixupKindInfo(MCFixupKind Kind) const { 224 const static MCFixupKindInfo LittleEndianInfos[Mips::NumTargetFixupKinds] = { 225 // This table *must* be in same the order of fixup_* kinds in 226 // MipsFixupKinds.h. 227 // 228 // name offset bits flags 229 { "fixup_Mips_16", 0, 16, 0 }, 230 { "fixup_Mips_32", 0, 32, 0 }, 231 { "fixup_Mips_REL32", 0, 32, 0 }, 232 { "fixup_Mips_26", 0, 26, 0 }, 233 { "fixup_Mips_HI16", 0, 16, 0 }, 234 { "fixup_Mips_LO16", 0, 16, 0 }, 235 { "fixup_Mips_GPREL16", 0, 16, 0 }, 236 { "fixup_Mips_LITERAL", 0, 16, 0 }, 237 { "fixup_Mips_GOT_Global", 0, 16, 0 }, 238 { "fixup_Mips_GOT_Local", 0, 16, 0 }, 239 { "fixup_Mips_PC16", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 240 { "fixup_Mips_CALL16", 0, 16, 0 }, 241 { "fixup_Mips_GPREL32", 0, 32, 0 }, 242 { "fixup_Mips_SHIFT5", 6, 5, 0 }, 243 { "fixup_Mips_SHIFT6", 6, 5, 0 }, 244 { "fixup_Mips_64", 0, 64, 0 }, 245 { "fixup_Mips_TLSGD", 0, 16, 0 }, 246 { "fixup_Mips_GOTTPREL", 0, 16, 0 }, 247 { "fixup_Mips_TPREL_HI", 0, 16, 0 }, 248 { "fixup_Mips_TPREL_LO", 0, 16, 0 }, 249 { "fixup_Mips_TLSLDM", 0, 16, 0 }, 250 { "fixup_Mips_DTPREL_HI", 0, 16, 0 }, 251 { "fixup_Mips_DTPREL_LO", 0, 16, 0 }, 252 { "fixup_Mips_Branch_PCRel", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 253 { "fixup_Mips_GPOFF_HI", 0, 16, 0 }, 254 { "fixup_Mips_GPOFF_LO", 0, 16, 0 }, 255 { "fixup_Mips_GOT_PAGE", 0, 16, 0 }, 256 { "fixup_Mips_GOT_OFST", 0, 16, 0 }, 257 { "fixup_Mips_GOT_DISP", 0, 16, 0 }, 258 { "fixup_Mips_HIGHER", 0, 16, 0 }, 259 { "fixup_Mips_HIGHEST", 0, 16, 0 }, 260 { "fixup_Mips_GOT_HI16", 0, 16, 0 }, 261 { "fixup_Mips_GOT_LO16", 0, 16, 0 }, 262 { "fixup_Mips_CALL_HI16", 0, 16, 0 }, 263 { "fixup_Mips_CALL_LO16", 0, 16, 0 }, 264 { "fixup_Mips_PC18_S3", 0, 18, MCFixupKindInfo::FKF_IsPCRel }, 265 { "fixup_MIPS_PC19_S2", 0, 19, MCFixupKindInfo::FKF_IsPCRel }, 266 { "fixup_MIPS_PC21_S2", 0, 21, MCFixupKindInfo::FKF_IsPCRel }, 267 { "fixup_MIPS_PC26_S2", 0, 26, MCFixupKindInfo::FKF_IsPCRel }, 268 { "fixup_MIPS_PCHI16", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 269 { "fixup_MIPS_PCLO16", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 270 { "fixup_MICROMIPS_26_S1", 0, 26, 0 }, 271 { "fixup_MICROMIPS_HI16", 0, 16, 0 }, 272 { "fixup_MICROMIPS_LO16", 0, 16, 0 }, 273 { "fixup_MICROMIPS_GOT16", 0, 16, 0 }, 274 { "fixup_MICROMIPS_PC16_S1", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 275 { "fixup_MICROMIPS_CALL16", 0, 16, 0 }, 276 { "fixup_MICROMIPS_GOT_DISP", 0, 16, 0 }, 277 { "fixup_MICROMIPS_GOT_PAGE", 0, 16, 0 }, 278 { "fixup_MICROMIPS_GOT_OFST", 0, 16, 0 }, 279 { "fixup_MICROMIPS_TLS_GD", 0, 16, 0 }, 280 { "fixup_MICROMIPS_TLS_LDM", 0, 16, 0 }, 281 { "fixup_MICROMIPS_TLS_DTPREL_HI16", 0, 16, 0 }, 282 { "fixup_MICROMIPS_TLS_DTPREL_LO16", 0, 16, 0 }, 283 { "fixup_MICROMIPS_TLS_TPREL_HI16", 0, 16, 0 }, 284 { "fixup_MICROMIPS_TLS_TPREL_LO16", 0, 16, 0 } 285 }; 286 287 const static MCFixupKindInfo BigEndianInfos[Mips::NumTargetFixupKinds] = { 288 // This table *must* be in same the order of fixup_* kinds in 289 // MipsFixupKinds.h. 290 // 291 // name offset bits flags 292 { "fixup_Mips_16", 16, 16, 0 }, 293 { "fixup_Mips_32", 0, 32, 0 }, 294 { "fixup_Mips_REL32", 0, 32, 0 }, 295 { "fixup_Mips_26", 6, 26, 0 }, 296 { "fixup_Mips_HI16", 16, 16, 0 }, 297 { "fixup_Mips_LO16", 16, 16, 0 }, 298 { "fixup_Mips_GPREL16", 16, 16, 0 }, 299 { "fixup_Mips_LITERAL", 16, 16, 0 }, 300 { "fixup_Mips_GOT_Global", 16, 16, 0 }, 301 { "fixup_Mips_GOT_Local", 16, 16, 0 }, 302 { "fixup_Mips_PC16", 16, 16, MCFixupKindInfo::FKF_IsPCRel }, 303 { "fixup_Mips_CALL16", 16, 16, 0 }, 304 { "fixup_Mips_GPREL32", 0, 32, 0 }, 305 { "fixup_Mips_SHIFT5", 21, 5, 0 }, 306 { "fixup_Mips_SHIFT6", 21, 5, 0 }, 307 { "fixup_Mips_64", 0, 64, 0 }, 308 { "fixup_Mips_TLSGD", 16, 16, 0 }, 309 { "fixup_Mips_GOTTPREL", 16, 16, 0 }, 310 { "fixup_Mips_TPREL_HI", 16, 16, 0 }, 311 { "fixup_Mips_TPREL_LO", 16, 16, 0 }, 312 { "fixup_Mips_TLSLDM", 16, 16, 0 }, 313 { "fixup_Mips_DTPREL_HI", 16, 16, 0 }, 314 { "fixup_Mips_DTPREL_LO", 16, 16, 0 }, 315 { "fixup_Mips_Branch_PCRel",16, 16, MCFixupKindInfo::FKF_IsPCRel }, 316 { "fixup_Mips_GPOFF_HI", 16, 16, 0 }, 317 { "fixup_Mips_GPOFF_LO", 16, 16, 0 }, 318 { "fixup_Mips_GOT_PAGE", 16, 16, 0 }, 319 { "fixup_Mips_GOT_OFST", 16, 16, 0 }, 320 { "fixup_Mips_GOT_DISP", 16, 16, 0 }, 321 { "fixup_Mips_HIGHER", 16, 16, 0 }, 322 { "fixup_Mips_HIGHEST", 16, 16, 0 }, 323 { "fixup_Mips_GOT_HI16", 16, 16, 0 }, 324 { "fixup_Mips_GOT_LO16", 16, 16, 0 }, 325 { "fixup_Mips_CALL_HI16", 16, 16, 0 }, 326 { "fixup_Mips_CALL_LO16", 16, 16, 0 }, 327 { "fixup_Mips_PC18_S3", 14, 18, MCFixupKindInfo::FKF_IsPCRel }, 328 { "fixup_MIPS_PC19_S2", 13, 19, MCFixupKindInfo::FKF_IsPCRel }, 329 { "fixup_MIPS_PC21_S2", 11, 21, MCFixupKindInfo::FKF_IsPCRel }, 330 { "fixup_MIPS_PC26_S2", 6, 26, MCFixupKindInfo::FKF_IsPCRel }, 331 { "fixup_MIPS_PCHI16", 16, 16, MCFixupKindInfo::FKF_IsPCRel }, 332 { "fixup_MIPS_PCLO16", 16, 16, MCFixupKindInfo::FKF_IsPCRel }, 333 { "fixup_MICROMIPS_26_S1", 6, 26, 0 }, 334 { "fixup_MICROMIPS_HI16", 16, 16, 0 }, 335 { "fixup_MICROMIPS_LO16", 16, 16, 0 }, 336 { "fixup_MICROMIPS_GOT16", 16, 16, 0 }, 337 { "fixup_MICROMIPS_PC16_S1",16, 16, MCFixupKindInfo::FKF_IsPCRel }, 338 { "fixup_MICROMIPS_CALL16", 16, 16, 0 }, 339 { "fixup_MICROMIPS_GOT_DISP", 16, 16, 0 }, 340 { "fixup_MICROMIPS_GOT_PAGE", 16, 16, 0 }, 341 { "fixup_MICROMIPS_GOT_OFST", 16, 16, 0 }, 342 { "fixup_MICROMIPS_TLS_GD", 16, 16, 0 }, 343 { "fixup_MICROMIPS_TLS_LDM", 16, 16, 0 }, 344 { "fixup_MICROMIPS_TLS_DTPREL_HI16", 16, 16, 0 }, 345 { "fixup_MICROMIPS_TLS_DTPREL_LO16", 16, 16, 0 }, 346 { "fixup_MICROMIPS_TLS_TPREL_HI16", 16, 16, 0 }, 347 { "fixup_MICROMIPS_TLS_TPREL_LO16", 16, 16, 0 } 348 }; 349 350 if (Kind < FirstTargetFixupKind) 351 return MCAsmBackend::getFixupKindInfo(Kind); 352 353 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && 354 "Invalid kind!"); 355 356 if (IsLittle) 357 return LittleEndianInfos[Kind - FirstTargetFixupKind]; 358 return BigEndianInfos[Kind - FirstTargetFixupKind]; 359} 360 361/// WriteNopData - Write an (optimal) nop sequence of Count bytes 362/// to the given output. If the target cannot generate such a sequence, 363/// it should return an error. 364/// 365/// \return - True on success. 366bool MipsAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const { 367 // Check for a less than instruction size number of bytes 368 // FIXME: 16 bit instructions are not handled yet here. 369 // We shouldn't be using a hard coded number for instruction size. 370 if (Count % 4) return false; 371 372 uint64_t NumNops = Count / 4; 373 for (uint64_t i = 0; i != NumNops; ++i) 374 OW->Write32(0); 375 return true; 376} 377 378/// processFixupValue - Target hook to process the literal value of a fixup 379/// if necessary. 380void MipsAsmBackend::processFixupValue(const MCAssembler &Asm, 381 const MCAsmLayout &Layout, 382 const MCFixup &Fixup, 383 const MCFragment *DF, 384 const MCValue &Target, 385 uint64_t &Value, 386 bool &IsResolved) { 387 // At this point we'll ignore the value returned by adjustFixupValue as 388 // we are only checking if the fixup can be applied correctly. We have 389 // access to MCContext from here which allows us to report a fatal error 390 // with *possibly* a source code location. 391 (void)adjustFixupValue(Fixup, Value, &Asm.getContext()); 392} 393 394// MCAsmBackend 395MCAsmBackend *llvm::createMipsAsmBackendEL32(const Target &T, 396 const MCRegisterInfo &MRI, 397 StringRef TT, 398 StringRef CPU) { 399 return new MipsAsmBackend(T, Triple(TT).getOS(), 400 /*IsLittle*/true, /*Is64Bit*/false); 401} 402 403MCAsmBackend *llvm::createMipsAsmBackendEB32(const Target &T, 404 const MCRegisterInfo &MRI, 405 StringRef TT, 406 StringRef CPU) { 407 return new MipsAsmBackend(T, Triple(TT).getOS(), 408 /*IsLittle*/false, /*Is64Bit*/false); 409} 410 411MCAsmBackend *llvm::createMipsAsmBackendEL64(const Target &T, 412 const MCRegisterInfo &MRI, 413 StringRef TT, 414 StringRef CPU) { 415 return new MipsAsmBackend(T, Triple(TT).getOS(), 416 /*IsLittle*/true, /*Is64Bit*/true); 417} 418 419MCAsmBackend *llvm::createMipsAsmBackendEB64(const Target &T, 420 const MCRegisterInfo &MRI, 421 StringRef TT, 422 StringRef CPU) { 423 return new MipsAsmBackend(T, Triple(TT).getOS(), 424 /*IsLittle*/false, /*Is64Bit*/true); 425} 426