1 //===- MCExpr.cpp - Assembly Level Expression Implementation --------------===// 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 "llvm/MC/MCExpr.h" 10 #include "llvm/ADT/Statistic.h" 11 #include "llvm/ADT/StringExtras.h" 12 #include "llvm/ADT/StringSwitch.h" 13 #include "llvm/Config/llvm-config.h" 14 #include "llvm/MC/MCAsmBackend.h" 15 #include "llvm/MC/MCAsmInfo.h" 16 #include "llvm/MC/MCAsmLayout.h" 17 #include "llvm/MC/MCAssembler.h" 18 #include "llvm/MC/MCContext.h" 19 #include "llvm/MC/MCObjectWriter.h" 20 #include "llvm/MC/MCSymbol.h" 21 #include "llvm/MC/MCValue.h" 22 #include "llvm/Support/Casting.h" 23 #include "llvm/Support/Compiler.h" 24 #include "llvm/Support/Debug.h" 25 #include "llvm/Support/ErrorHandling.h" 26 #include "llvm/Support/raw_ostream.h" 27 #include <cassert> 28 #include <cstdint> 29 30 using namespace llvm; 31 32 #define DEBUG_TYPE "mcexpr" 33 34 namespace { 35 namespace stats { 36 37 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations"); 38 39 } // end namespace stats 40 } // end anonymous namespace 41 42 void MCExpr::print(raw_ostream &OS, const MCAsmInfo *MAI, bool InParens) const { 43 switch (getKind()) { 44 case MCExpr::Target: 45 return cast<MCTargetExpr>(this)->printImpl(OS, MAI); 46 case MCExpr::Constant: { 47 auto Value = cast<MCConstantExpr>(*this).getValue(); 48 auto PrintInHex = cast<MCConstantExpr>(*this).useHexFormat(); 49 auto SizeInBytes = cast<MCConstantExpr>(*this).getSizeInBytes(); 50 if (Value < 0 && MAI && !MAI->supportsSignedData()) 51 PrintInHex = true; 52 if (PrintInHex) 53 switch (SizeInBytes) { 54 default: 55 OS << "0x" << Twine::utohexstr(Value); 56 break; 57 case 1: 58 OS << format("0x%02" PRIx64, Value); 59 break; 60 case 2: 61 OS << format("0x%04" PRIx64, Value); 62 break; 63 case 4: 64 OS << format("0x%08" PRIx64, Value); 65 break; 66 case 8: 67 OS << format("0x%016" PRIx64, Value); 68 break; 69 } 70 else 71 OS << Value; 72 return; 73 } 74 case MCExpr::SymbolRef: { 75 const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this); 76 const MCSymbol &Sym = SRE.getSymbol(); 77 // Parenthesize names that start with $ so that they don't look like 78 // absolute names. 79 bool UseParens = 80 !InParens && !Sym.getName().empty() && Sym.getName()[0] == '$'; 81 if (UseParens) { 82 OS << '('; 83 Sym.print(OS, MAI); 84 OS << ')'; 85 } else 86 Sym.print(OS, MAI); 87 88 const MCSymbolRefExpr::VariantKind Kind = SRE.getKind(); 89 if (Kind != MCSymbolRefExpr::VK_None) { 90 if (MAI && MAI->useParensForSymbolVariant()) // ARM 91 OS << '(' << MCSymbolRefExpr::getVariantKindName(Kind) << ')'; 92 else 93 OS << '@' << MCSymbolRefExpr::getVariantKindName(Kind); 94 } 95 96 return; 97 } 98 99 case MCExpr::Unary: { 100 const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this); 101 switch (UE.getOpcode()) { 102 case MCUnaryExpr::LNot: OS << '!'; break; 103 case MCUnaryExpr::Minus: OS << '-'; break; 104 case MCUnaryExpr::Not: OS << '~'; break; 105 case MCUnaryExpr::Plus: OS << '+'; break; 106 } 107 bool Binary = UE.getSubExpr()->getKind() == MCExpr::Binary; 108 if (Binary) OS << "("; 109 UE.getSubExpr()->print(OS, MAI); 110 if (Binary) OS << ")"; 111 return; 112 } 113 114 case MCExpr::Binary: { 115 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this); 116 117 // Only print parens around the LHS if it is non-trivial. 118 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) { 119 BE.getLHS()->print(OS, MAI); 120 } else { 121 OS << '('; 122 BE.getLHS()->print(OS, MAI); 123 OS << ')'; 124 } 125 126 switch (BE.getOpcode()) { 127 case MCBinaryExpr::Add: 128 // Print "X-42" instead of "X+-42". 129 if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) { 130 if (RHSC->getValue() < 0) { 131 OS << RHSC->getValue(); 132 return; 133 } 134 } 135 136 OS << '+'; 137 break; 138 case MCBinaryExpr::AShr: OS << ">>"; break; 139 case MCBinaryExpr::And: OS << '&'; break; 140 case MCBinaryExpr::Div: OS << '/'; break; 141 case MCBinaryExpr::EQ: OS << "=="; break; 142 case MCBinaryExpr::GT: OS << '>'; break; 143 case MCBinaryExpr::GTE: OS << ">="; break; 144 case MCBinaryExpr::LAnd: OS << "&&"; break; 145 case MCBinaryExpr::LOr: OS << "||"; break; 146 case MCBinaryExpr::LShr: OS << ">>"; break; 147 case MCBinaryExpr::LT: OS << '<'; break; 148 case MCBinaryExpr::LTE: OS << "<="; break; 149 case MCBinaryExpr::Mod: OS << '%'; break; 150 case MCBinaryExpr::Mul: OS << '*'; break; 151 case MCBinaryExpr::NE: OS << "!="; break; 152 case MCBinaryExpr::Or: OS << '|'; break; 153 case MCBinaryExpr::OrNot: OS << '!'; break; 154 case MCBinaryExpr::Shl: OS << "<<"; break; 155 case MCBinaryExpr::Sub: OS << '-'; break; 156 case MCBinaryExpr::Xor: OS << '^'; break; 157 } 158 159 // Only print parens around the LHS if it is non-trivial. 160 if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) { 161 BE.getRHS()->print(OS, MAI); 162 } else { 163 OS << '('; 164 BE.getRHS()->print(OS, MAI); 165 OS << ')'; 166 } 167 return; 168 } 169 } 170 171 llvm_unreachable("Invalid expression kind!"); 172 } 173 174 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 175 LLVM_DUMP_METHOD void MCExpr::dump() const { 176 dbgs() << *this; 177 dbgs() << '\n'; 178 } 179 #endif 180 181 /* *** */ 182 183 const MCBinaryExpr *MCBinaryExpr::create(Opcode Opc, const MCExpr *LHS, 184 const MCExpr *RHS, MCContext &Ctx, 185 SMLoc Loc) { 186 return new (Ctx) MCBinaryExpr(Opc, LHS, RHS, Loc); 187 } 188 189 const MCUnaryExpr *MCUnaryExpr::create(Opcode Opc, const MCExpr *Expr, 190 MCContext &Ctx, SMLoc Loc) { 191 return new (Ctx) MCUnaryExpr(Opc, Expr, Loc); 192 } 193 194 const MCConstantExpr *MCConstantExpr::create(int64_t Value, MCContext &Ctx, 195 bool PrintInHex, 196 unsigned SizeInBytes) { 197 return new (Ctx) MCConstantExpr(Value, PrintInHex, SizeInBytes); 198 } 199 200 /* *** */ 201 202 MCSymbolRefExpr::MCSymbolRefExpr(const MCSymbol *Symbol, VariantKind Kind, 203 const MCAsmInfo *MAI, SMLoc Loc) 204 : MCExpr(MCExpr::SymbolRef, Loc, 205 encodeSubclassData(Kind, MAI->hasSubsectionsViaSymbols())), 206 Symbol(Symbol) { 207 assert(Symbol); 208 } 209 210 const MCSymbolRefExpr *MCSymbolRefExpr::create(const MCSymbol *Sym, 211 VariantKind Kind, 212 MCContext &Ctx, SMLoc Loc) { 213 return new (Ctx) MCSymbolRefExpr(Sym, Kind, Ctx.getAsmInfo(), Loc); 214 } 215 216 const MCSymbolRefExpr *MCSymbolRefExpr::create(StringRef Name, VariantKind Kind, 217 MCContext &Ctx) { 218 return create(Ctx.getOrCreateSymbol(Name), Kind, Ctx); 219 } 220 221 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) { 222 switch (Kind) { 223 case VK_Invalid: return "<<invalid>>"; 224 case VK_None: return "<<none>>"; 225 226 case VK_DTPOFF: return "DTPOFF"; 227 case VK_DTPREL: return "DTPREL"; 228 case VK_GOT: return "GOT"; 229 case VK_GOTOFF: return "GOTOFF"; 230 case VK_GOTREL: return "GOTREL"; 231 case VK_PCREL: return "PCREL"; 232 case VK_GOTPCREL: return "GOTPCREL"; 233 case VK_GOTTPOFF: return "GOTTPOFF"; 234 case VK_INDNTPOFF: return "INDNTPOFF"; 235 case VK_NTPOFF: return "NTPOFF"; 236 case VK_GOTNTPOFF: return "GOTNTPOFF"; 237 case VK_PLT: return "PLT"; 238 case VK_TLSGD: return "TLSGD"; 239 case VK_TLSLD: return "TLSLD"; 240 case VK_TLSLDM: return "TLSLDM"; 241 case VK_TPOFF: return "TPOFF"; 242 case VK_TPREL: return "TPREL"; 243 case VK_TLSCALL: return "tlscall"; 244 case VK_TLSDESC: return "tlsdesc"; 245 case VK_TLVP: return "TLVP"; 246 case VK_TLVPPAGE: return "TLVPPAGE"; 247 case VK_TLVPPAGEOFF: return "TLVPPAGEOFF"; 248 case VK_PAGE: return "PAGE"; 249 case VK_PAGEOFF: return "PAGEOFF"; 250 case VK_GOTPAGE: return "GOTPAGE"; 251 case VK_GOTPAGEOFF: return "GOTPAGEOFF"; 252 case VK_SECREL: return "SECREL32"; 253 case VK_SIZE: return "SIZE"; 254 case VK_WEAKREF: return "WEAKREF"; 255 case VK_X86_ABS8: return "ABS8"; 256 case VK_X86_PLTOFF: return "PLTOFF"; 257 case VK_ARM_NONE: return "none"; 258 case VK_ARM_GOT_PREL: return "GOT_PREL"; 259 case VK_ARM_TARGET1: return "target1"; 260 case VK_ARM_TARGET2: return "target2"; 261 case VK_ARM_PREL31: return "prel31"; 262 case VK_ARM_SBREL: return "sbrel"; 263 case VK_ARM_TLSLDO: return "tlsldo"; 264 case VK_ARM_TLSDESCSEQ: return "tlsdescseq"; 265 case VK_AVR_NONE: return "none"; 266 case VK_AVR_LO8: return "lo8"; 267 case VK_AVR_HI8: return "hi8"; 268 case VK_AVR_HLO8: return "hlo8"; 269 case VK_AVR_DIFF8: return "diff8"; 270 case VK_AVR_DIFF16: return "diff16"; 271 case VK_AVR_DIFF32: return "diff32"; 272 case VK_PPC_LO: return "l"; 273 case VK_PPC_HI: return "h"; 274 case VK_PPC_HA: return "ha"; 275 case VK_PPC_HIGH: return "high"; 276 case VK_PPC_HIGHA: return "higha"; 277 case VK_PPC_HIGHER: return "higher"; 278 case VK_PPC_HIGHERA: return "highera"; 279 case VK_PPC_HIGHEST: return "highest"; 280 case VK_PPC_HIGHESTA: return "highesta"; 281 case VK_PPC_GOT_LO: return "got@l"; 282 case VK_PPC_GOT_HI: return "got@h"; 283 case VK_PPC_GOT_HA: return "got@ha"; 284 case VK_PPC_TOCBASE: return "tocbase"; 285 case VK_PPC_TOC: return "toc"; 286 case VK_PPC_TOC_LO: return "toc@l"; 287 case VK_PPC_TOC_HI: return "toc@h"; 288 case VK_PPC_TOC_HA: return "toc@ha"; 289 case VK_PPC_U: return "u"; 290 case VK_PPC_L: return "l"; 291 case VK_PPC_DTPMOD: return "dtpmod"; 292 case VK_PPC_TPREL_LO: return "tprel@l"; 293 case VK_PPC_TPREL_HI: return "tprel@h"; 294 case VK_PPC_TPREL_HA: return "tprel@ha"; 295 case VK_PPC_TPREL_HIGH: return "tprel@high"; 296 case VK_PPC_TPREL_HIGHA: return "tprel@higha"; 297 case VK_PPC_TPREL_HIGHER: return "tprel@higher"; 298 case VK_PPC_TPREL_HIGHERA: return "tprel@highera"; 299 case VK_PPC_TPREL_HIGHEST: return "tprel@highest"; 300 case VK_PPC_TPREL_HIGHESTA: return "tprel@highesta"; 301 case VK_PPC_DTPREL_LO: return "dtprel@l"; 302 case VK_PPC_DTPREL_HI: return "dtprel@h"; 303 case VK_PPC_DTPREL_HA: return "dtprel@ha"; 304 case VK_PPC_DTPREL_HIGH: return "dtprel@high"; 305 case VK_PPC_DTPREL_HIGHA: return "dtprel@higha"; 306 case VK_PPC_DTPREL_HIGHER: return "dtprel@higher"; 307 case VK_PPC_DTPREL_HIGHERA: return "dtprel@highera"; 308 case VK_PPC_DTPREL_HIGHEST: return "dtprel@highest"; 309 case VK_PPC_DTPREL_HIGHESTA: return "dtprel@highesta"; 310 case VK_PPC_GOT_TPREL: return "got@tprel"; 311 case VK_PPC_GOT_TPREL_LO: return "got@tprel@l"; 312 case VK_PPC_GOT_TPREL_HI: return "got@tprel@h"; 313 case VK_PPC_GOT_TPREL_HA: return "got@tprel@ha"; 314 case VK_PPC_GOT_DTPREL: return "got@dtprel"; 315 case VK_PPC_GOT_DTPREL_LO: return "got@dtprel@l"; 316 case VK_PPC_GOT_DTPREL_HI: return "got@dtprel@h"; 317 case VK_PPC_GOT_DTPREL_HA: return "got@dtprel@ha"; 318 case VK_PPC_TLS: return "tls"; 319 case VK_PPC_GOT_TLSGD: return "got@tlsgd"; 320 case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l"; 321 case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h"; 322 case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha"; 323 case VK_PPC_TLSGD: return "tlsgd"; 324 case VK_PPC_GOT_TLSLD: return "got@tlsld"; 325 case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l"; 326 case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h"; 327 case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha"; 328 case VK_PPC_GOT_PCREL: 329 return "got@pcrel"; 330 case VK_PPC_GOT_TLSGD_PCREL: 331 return "got@tlsgd@pcrel"; 332 case VK_PPC_GOT_TLSLD_PCREL: 333 return "got@tlsld@pcrel"; 334 case VK_PPC_GOT_TPREL_PCREL: 335 return "got@tprel@pcrel"; 336 case VK_PPC_TLS_PCREL: 337 return "tls@pcrel"; 338 case VK_PPC_TLSLD: return "tlsld"; 339 case VK_PPC_LOCAL: return "local"; 340 case VK_PPC_NOTOC: return "notoc"; 341 case VK_PPC_PCREL_OPT: return "<<invalid>>"; 342 case VK_COFF_IMGREL32: return "IMGREL"; 343 case VK_Hexagon_LO16: return "LO16"; 344 case VK_Hexagon_HI16: return "HI16"; 345 case VK_Hexagon_GPREL: return "GPREL"; 346 case VK_Hexagon_GD_GOT: return "GDGOT"; 347 case VK_Hexagon_LD_GOT: return "LDGOT"; 348 case VK_Hexagon_GD_PLT: return "GDPLT"; 349 case VK_Hexagon_LD_PLT: return "LDPLT"; 350 case VK_Hexagon_IE: return "IE"; 351 case VK_Hexagon_IE_GOT: return "IEGOT"; 352 case VK_WASM_TYPEINDEX: return "TYPEINDEX"; 353 case VK_WASM_MBREL: return "MBREL"; 354 case VK_WASM_TLSREL: return "TLSREL"; 355 case VK_WASM_TBREL: return "TBREL"; 356 case VK_AMDGPU_GOTPCREL32_LO: return "gotpcrel32@lo"; 357 case VK_AMDGPU_GOTPCREL32_HI: return "gotpcrel32@hi"; 358 case VK_AMDGPU_REL32_LO: return "rel32@lo"; 359 case VK_AMDGPU_REL32_HI: return "rel32@hi"; 360 case VK_AMDGPU_REL64: return "rel64"; 361 case VK_AMDGPU_ABS32_LO: return "abs32@lo"; 362 case VK_AMDGPU_ABS32_HI: return "abs32@hi"; 363 case VK_VE_HI32: return "hi"; 364 case VK_VE_LO32: return "lo"; 365 case VK_VE_PC_HI32: return "pc_hi"; 366 case VK_VE_PC_LO32: return "pc_lo"; 367 case VK_VE_GOT_HI32: return "got_hi"; 368 case VK_VE_GOT_LO32: return "got_lo"; 369 case VK_VE_GOTOFF_HI32: return "gotoff_hi"; 370 case VK_VE_GOTOFF_LO32: return "gotoff_lo"; 371 case VK_VE_PLT_HI32: return "plt_hi"; 372 case VK_VE_PLT_LO32: return "plt_lo"; 373 case VK_VE_TLS_GD_HI32: return "tls_gd_hi"; 374 case VK_VE_TLS_GD_LO32: return "tls_gd_lo"; 375 case VK_VE_TPOFF_HI32: return "tpoff_hi"; 376 case VK_VE_TPOFF_LO32: return "tpoff_lo"; 377 } 378 llvm_unreachable("Invalid variant kind"); 379 } 380 381 MCSymbolRefExpr::VariantKind 382 MCSymbolRefExpr::getVariantKindForName(StringRef Name) { 383 return StringSwitch<VariantKind>(Name.lower()) 384 .Case("dtprel", VK_DTPREL) 385 .Case("dtpoff", VK_DTPOFF) 386 .Case("got", VK_GOT) 387 .Case("gotoff", VK_GOTOFF) 388 .Case("gotrel", VK_GOTREL) 389 .Case("pcrel", VK_PCREL) 390 .Case("gotpcrel", VK_GOTPCREL) 391 .Case("gottpoff", VK_GOTTPOFF) 392 .Case("indntpoff", VK_INDNTPOFF) 393 .Case("ntpoff", VK_NTPOFF) 394 .Case("gotntpoff", VK_GOTNTPOFF) 395 .Case("plt", VK_PLT) 396 .Case("tlscall", VK_TLSCALL) 397 .Case("tlsdesc", VK_TLSDESC) 398 .Case("tlsgd", VK_TLSGD) 399 .Case("tlsld", VK_TLSLD) 400 .Case("tlsldm", VK_TLSLDM) 401 .Case("tpoff", VK_TPOFF) 402 .Case("tprel", VK_TPREL) 403 .Case("tlvp", VK_TLVP) 404 .Case("tlvppage", VK_TLVPPAGE) 405 .Case("tlvppageoff", VK_TLVPPAGEOFF) 406 .Case("page", VK_PAGE) 407 .Case("pageoff", VK_PAGEOFF) 408 .Case("gotpage", VK_GOTPAGE) 409 .Case("gotpageoff", VK_GOTPAGEOFF) 410 .Case("imgrel", VK_COFF_IMGREL32) 411 .Case("secrel32", VK_SECREL) 412 .Case("size", VK_SIZE) 413 .Case("abs8", VK_X86_ABS8) 414 .Case("pltoff", VK_X86_PLTOFF) 415 .Case("l", VK_PPC_LO) 416 .Case("h", VK_PPC_HI) 417 .Case("ha", VK_PPC_HA) 418 .Case("high", VK_PPC_HIGH) 419 .Case("higha", VK_PPC_HIGHA) 420 .Case("higher", VK_PPC_HIGHER) 421 .Case("highera", VK_PPC_HIGHERA) 422 .Case("highest", VK_PPC_HIGHEST) 423 .Case("highesta", VK_PPC_HIGHESTA) 424 .Case("got@l", VK_PPC_GOT_LO) 425 .Case("got@h", VK_PPC_GOT_HI) 426 .Case("got@ha", VK_PPC_GOT_HA) 427 .Case("local", VK_PPC_LOCAL) 428 .Case("tocbase", VK_PPC_TOCBASE) 429 .Case("toc", VK_PPC_TOC) 430 .Case("toc@l", VK_PPC_TOC_LO) 431 .Case("toc@h", VK_PPC_TOC_HI) 432 .Case("toc@ha", VK_PPC_TOC_HA) 433 .Case("u", VK_PPC_U) 434 .Case("l", VK_PPC_L) 435 .Case("tls", VK_PPC_TLS) 436 .Case("dtpmod", VK_PPC_DTPMOD) 437 .Case("tprel@l", VK_PPC_TPREL_LO) 438 .Case("tprel@h", VK_PPC_TPREL_HI) 439 .Case("tprel@ha", VK_PPC_TPREL_HA) 440 .Case("tprel@high", VK_PPC_TPREL_HIGH) 441 .Case("tprel@higha", VK_PPC_TPREL_HIGHA) 442 .Case("tprel@higher", VK_PPC_TPREL_HIGHER) 443 .Case("tprel@highera", VK_PPC_TPREL_HIGHERA) 444 .Case("tprel@highest", VK_PPC_TPREL_HIGHEST) 445 .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA) 446 .Case("dtprel@l", VK_PPC_DTPREL_LO) 447 .Case("dtprel@h", VK_PPC_DTPREL_HI) 448 .Case("dtprel@ha", VK_PPC_DTPREL_HA) 449 .Case("dtprel@high", VK_PPC_DTPREL_HIGH) 450 .Case("dtprel@higha", VK_PPC_DTPREL_HIGHA) 451 .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER) 452 .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA) 453 .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST) 454 .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA) 455 .Case("got@tprel", VK_PPC_GOT_TPREL) 456 .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO) 457 .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI) 458 .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA) 459 .Case("got@dtprel", VK_PPC_GOT_DTPREL) 460 .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO) 461 .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI) 462 .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA) 463 .Case("got@tlsgd", VK_PPC_GOT_TLSGD) 464 .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO) 465 .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI) 466 .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA) 467 .Case("got@tlsld", VK_PPC_GOT_TLSLD) 468 .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO) 469 .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI) 470 .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA) 471 .Case("got@pcrel", VK_PPC_GOT_PCREL) 472 .Case("got@tlsgd@pcrel", VK_PPC_GOT_TLSGD_PCREL) 473 .Case("got@tlsld@pcrel", VK_PPC_GOT_TLSLD_PCREL) 474 .Case("got@tprel@pcrel", VK_PPC_GOT_TPREL_PCREL) 475 .Case("tls@pcrel", VK_PPC_TLS_PCREL) 476 .Case("notoc", VK_PPC_NOTOC) 477 .Case("gdgot", VK_Hexagon_GD_GOT) 478 .Case("gdplt", VK_Hexagon_GD_PLT) 479 .Case("iegot", VK_Hexagon_IE_GOT) 480 .Case("ie", VK_Hexagon_IE) 481 .Case("ldgot", VK_Hexagon_LD_GOT) 482 .Case("ldplt", VK_Hexagon_LD_PLT) 483 .Case("none", VK_ARM_NONE) 484 .Case("got_prel", VK_ARM_GOT_PREL) 485 .Case("target1", VK_ARM_TARGET1) 486 .Case("target2", VK_ARM_TARGET2) 487 .Case("prel31", VK_ARM_PREL31) 488 .Case("sbrel", VK_ARM_SBREL) 489 .Case("tlsldo", VK_ARM_TLSLDO) 490 .Case("lo8", VK_AVR_LO8) 491 .Case("hi8", VK_AVR_HI8) 492 .Case("hlo8", VK_AVR_HLO8) 493 .Case("typeindex", VK_WASM_TYPEINDEX) 494 .Case("tbrel", VK_WASM_TBREL) 495 .Case("mbrel", VK_WASM_MBREL) 496 .Case("tlsrel", VK_WASM_TLSREL) 497 .Case("gotpcrel32@lo", VK_AMDGPU_GOTPCREL32_LO) 498 .Case("gotpcrel32@hi", VK_AMDGPU_GOTPCREL32_HI) 499 .Case("rel32@lo", VK_AMDGPU_REL32_LO) 500 .Case("rel32@hi", VK_AMDGPU_REL32_HI) 501 .Case("rel64", VK_AMDGPU_REL64) 502 .Case("abs32@lo", VK_AMDGPU_ABS32_LO) 503 .Case("abs32@hi", VK_AMDGPU_ABS32_HI) 504 .Case("hi", VK_VE_HI32) 505 .Case("lo", VK_VE_LO32) 506 .Case("pc_hi", VK_VE_PC_HI32) 507 .Case("pc_lo", VK_VE_PC_LO32) 508 .Case("got_hi", VK_VE_GOT_HI32) 509 .Case("got_lo", VK_VE_GOT_LO32) 510 .Case("gotoff_hi", VK_VE_GOTOFF_HI32) 511 .Case("gotoff_lo", VK_VE_GOTOFF_LO32) 512 .Case("plt_hi", VK_VE_PLT_HI32) 513 .Case("plt_lo", VK_VE_PLT_LO32) 514 .Case("tls_gd_hi", VK_VE_TLS_GD_HI32) 515 .Case("tls_gd_lo", VK_VE_TLS_GD_LO32) 516 .Case("tpoff_hi", VK_VE_TPOFF_HI32) 517 .Case("tpoff_lo", VK_VE_TPOFF_LO32) 518 .Default(VK_Invalid); 519 } 520 521 /* *** */ 522 523 void MCTargetExpr::anchor() {} 524 525 /* *** */ 526 527 bool MCExpr::evaluateAsAbsolute(int64_t &Res) const { 528 return evaluateAsAbsolute(Res, nullptr, nullptr, nullptr, false); 529 } 530 531 bool MCExpr::evaluateAsAbsolute(int64_t &Res, 532 const MCAsmLayout &Layout) const { 533 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr, false); 534 } 535 536 bool MCExpr::evaluateAsAbsolute(int64_t &Res, 537 const MCAsmLayout &Layout, 538 const SectionAddrMap &Addrs) const { 539 // Setting InSet causes us to absolutize differences across sections and that 540 // is what the MachO writer uses Addrs for. 541 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs, true); 542 } 543 544 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const { 545 return evaluateAsAbsolute(Res, &Asm, nullptr, nullptr, false); 546 } 547 548 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm) const { 549 return evaluateAsAbsolute(Res, Asm, nullptr, nullptr, false); 550 } 551 552 bool MCExpr::evaluateKnownAbsolute(int64_t &Res, 553 const MCAsmLayout &Layout) const { 554 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr, 555 true); 556 } 557 558 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, 559 const MCAsmLayout *Layout, 560 const SectionAddrMap *Addrs, bool InSet) const { 561 MCValue Value; 562 563 // Fast path constants. 564 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) { 565 Res = CE->getValue(); 566 return true; 567 } 568 569 bool IsRelocatable = 570 evaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs, InSet); 571 572 // Record the current value. 573 Res = Value.getConstant(); 574 575 return IsRelocatable && Value.isAbsolute(); 576 } 577 578 /// Helper method for \see EvaluateSymbolAdd(). 579 static void AttemptToFoldSymbolOffsetDifference( 580 const MCAssembler *Asm, const MCAsmLayout *Layout, 581 const SectionAddrMap *Addrs, bool InSet, const MCSymbolRefExpr *&A, 582 const MCSymbolRefExpr *&B, int64_t &Addend) { 583 if (!A || !B) 584 return; 585 586 const MCSymbol &SA = A->getSymbol(); 587 const MCSymbol &SB = B->getSymbol(); 588 589 if (SA.isUndefined() || SB.isUndefined()) 590 return; 591 592 if (!Asm->getWriter().isSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet)) 593 return; 594 595 auto FinalizeFolding = [&]() { 596 // Pointers to Thumb symbols need to have their low-bit set to allow 597 // for interworking. 598 if (Asm->isThumbFunc(&SA)) 599 Addend |= 1; 600 601 // If symbol is labeled as micromips, we set low-bit to ensure 602 // correct offset in .gcc_except_table 603 if (Asm->getBackend().isMicroMips(&SA)) 604 Addend |= 1; 605 606 // Clear the symbol expr pointers to indicate we have folded these 607 // operands. 608 A = B = nullptr; 609 }; 610 611 const MCFragment *FA = SA.getFragment(); 612 const MCFragment *FB = SB.getFragment(); 613 // If both symbols are in the same fragment, return the difference of their 614 // offsets 615 if (FA == FB && !SA.isVariable() && !SA.isUnset() && !SB.isVariable() && 616 !SB.isUnset()) { 617 Addend += SA.getOffset() - SB.getOffset(); 618 return FinalizeFolding(); 619 } 620 621 const MCSection &SecA = *FA->getParent(); 622 const MCSection &SecB = *FB->getParent(); 623 624 if ((&SecA != &SecB) && !Addrs) 625 return; 626 627 if (Layout) { 628 // One of the symbol involved is part of a fragment being laid out. Quit now 629 // to avoid a self loop. 630 if (!Layout->canGetFragmentOffset(FA) || !Layout->canGetFragmentOffset(FB)) 631 return; 632 633 // Eagerly evaluate when layout is finalized. 634 Addend += Layout->getSymbolOffset(A->getSymbol()) - 635 Layout->getSymbolOffset(B->getSymbol()); 636 if (Addrs && (&SecA != &SecB)) 637 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB)); 638 639 FinalizeFolding(); 640 } else { 641 // When layout is not finalized, our ability to resolve differences between 642 // symbols is limited to specific cases where the fragments between two 643 // symbols (including the fragments the symbols are defined in) are 644 // fixed-size fragments so the difference can be calculated. For example, 645 // this is important when the Subtarget is changed and a new MCDataFragment 646 // is created in the case of foo: instr; .arch_extension ext; instr .if . - 647 // foo. 648 if (SA.isVariable() || SA.isUnset() || SB.isVariable() || SB.isUnset() || 649 FA->getKind() != MCFragment::FT_Data || 650 FB->getKind() != MCFragment::FT_Data || 651 FA->getSubsectionNumber() != FB->getSubsectionNumber()) 652 return; 653 // Try to find a constant displacement from FA to FB, add the displacement 654 // between the offset in FA of SA and the offset in FB of SB. 655 int64_t Displacement = SA.getOffset() - SB.getOffset(); 656 for (auto FI = FB->getIterator(), FE = SecA.end(); FI != FE; ++FI) { 657 if (&*FI == FA) { 658 Addend += Displacement; 659 return FinalizeFolding(); 660 } 661 662 if (FI->getKind() != MCFragment::FT_Data) 663 return; 664 Displacement += cast<MCDataFragment>(FI)->getContents().size(); 665 } 666 } 667 } 668 669 static bool canFold(const MCAssembler *Asm, const MCSymbolRefExpr *A, 670 const MCSymbolRefExpr *B, bool InSet) { 671 if (InSet) 672 return true; 673 674 if (!Asm->getBackend().requiresDiffExpressionRelocations()) 675 return true; 676 677 const MCSymbol &CheckSym = A ? A->getSymbol() : B->getSymbol(); 678 if (!CheckSym.isInSection()) 679 return true; 680 681 if (!CheckSym.getSection().hasInstructions()) 682 return true; 683 684 return false; 685 } 686 687 /// Evaluate the result of an add between (conceptually) two MCValues. 688 /// 689 /// This routine conceptually attempts to construct an MCValue: 690 /// Result = (Result_A - Result_B + Result_Cst) 691 /// from two MCValue's LHS and RHS where 692 /// Result = LHS + RHS 693 /// and 694 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 695 /// 696 /// This routine attempts to aggressively fold the operands such that the result 697 /// is representable in an MCValue, but may not always succeed. 698 /// 699 /// \returns True on success, false if the result is not representable in an 700 /// MCValue. 701 702 /// NOTE: It is really important to have both the Asm and Layout arguments. 703 /// They might look redundant, but this function can be used before layout 704 /// is done (see the object streamer for example) and having the Asm argument 705 /// lets us avoid relaxations early. 706 static bool 707 EvaluateSymbolicAdd(const MCAssembler *Asm, const MCAsmLayout *Layout, 708 const SectionAddrMap *Addrs, bool InSet, const MCValue &LHS, 709 const MCSymbolRefExpr *RHS_A, const MCSymbolRefExpr *RHS_B, 710 int64_t RHS_Cst, MCValue &Res) { 711 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy 712 // about dealing with modifiers. This will ultimately bite us, one day. 713 const MCSymbolRefExpr *LHS_A = LHS.getSymA(); 714 const MCSymbolRefExpr *LHS_B = LHS.getSymB(); 715 int64_t LHS_Cst = LHS.getConstant(); 716 717 // Fold the result constant immediately. 718 int64_t Result_Cst = LHS_Cst + RHS_Cst; 719 720 assert((!Layout || Asm) && 721 "Must have an assembler object if layout is given!"); 722 723 // If we have a layout, we can fold resolved differences. Do not do this if 724 // the backend requires this to be emitted as individual relocations, unless 725 // the InSet flag is set to get the current difference anyway (used for 726 // example to calculate symbol sizes). 727 if (Asm && canFold(Asm, LHS_A, LHS_B, InSet)) { 728 // First, fold out any differences which are fully resolved. By 729 // reassociating terms in 730 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 731 // we have the four possible differences: 732 // (LHS_A - LHS_B), 733 // (LHS_A - RHS_B), 734 // (RHS_A - LHS_B), 735 // (RHS_A - RHS_B). 736 // Since we are attempting to be as aggressive as possible about folding, we 737 // attempt to evaluate each possible alternative. 738 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B, 739 Result_Cst); 740 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B, 741 Result_Cst); 742 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B, 743 Result_Cst); 744 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B, 745 Result_Cst); 746 } 747 748 // We can't represent the addition or subtraction of two symbols. 749 if ((LHS_A && RHS_A) || (LHS_B && RHS_B)) 750 return false; 751 752 // At this point, we have at most one additive symbol and one subtractive 753 // symbol -- find them. 754 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A; 755 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B; 756 757 Res = MCValue::get(A, B, Result_Cst); 758 return true; 759 } 760 761 bool MCExpr::evaluateAsRelocatable(MCValue &Res, 762 const MCAsmLayout *Layout, 763 const MCFixup *Fixup) const { 764 MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr; 765 return evaluateAsRelocatableImpl(Res, Assembler, Layout, Fixup, nullptr, 766 false); 767 } 768 769 bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const { 770 MCAssembler *Assembler = &Layout.getAssembler(); 771 return evaluateAsRelocatableImpl(Res, Assembler, &Layout, nullptr, nullptr, 772 true); 773 } 774 775 static bool canExpand(const MCSymbol &Sym, bool InSet) { 776 const MCExpr *Expr = Sym.getVariableValue(); 777 const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr); 778 if (Inner) { 779 if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF) 780 return false; 781 } 782 783 if (InSet) 784 return true; 785 return !Sym.isInSection(); 786 } 787 788 bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm, 789 const MCAsmLayout *Layout, 790 const MCFixup *Fixup, 791 const SectionAddrMap *Addrs, 792 bool InSet) const { 793 ++stats::MCExprEvaluate; 794 795 switch (getKind()) { 796 case Target: 797 return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Layout, 798 Fixup); 799 800 case Constant: 801 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue()); 802 return true; 803 804 case SymbolRef: { 805 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 806 const MCSymbol &Sym = SRE->getSymbol(); 807 const auto Kind = SRE->getKind(); 808 809 // Evaluate recursively if this is a variable. 810 if (Sym.isVariable() && (Kind == MCSymbolRefExpr::VK_None || Layout) && 811 canExpand(Sym, InSet)) { 812 bool IsMachO = SRE->hasSubsectionsViaSymbols(); 813 if (Sym.getVariableValue()->evaluateAsRelocatableImpl( 814 Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO)) { 815 if (Kind != MCSymbolRefExpr::VK_None) { 816 if (Res.isAbsolute()) { 817 Res = MCValue::get(SRE, nullptr, 0); 818 return true; 819 } 820 // If the reference has a variant kind, we can only handle expressions 821 // which evaluate exactly to a single unadorned symbol. Attach the 822 // original VariantKind to SymA of the result. 823 if (Res.getRefKind() != MCSymbolRefExpr::VK_None || !Res.getSymA() || 824 Res.getSymB() || Res.getConstant()) 825 return false; 826 Res = 827 MCValue::get(MCSymbolRefExpr::create(&Res.getSymA()->getSymbol(), 828 Kind, Asm->getContext()), 829 Res.getSymB(), Res.getConstant(), Res.getRefKind()); 830 } 831 if (!IsMachO) 832 return true; 833 834 const MCSymbolRefExpr *A = Res.getSymA(); 835 const MCSymbolRefExpr *B = Res.getSymB(); 836 // FIXME: This is small hack. Given 837 // a = b + 4 838 // .long a 839 // the OS X assembler will completely drop the 4. We should probably 840 // include it in the relocation or produce an error if that is not 841 // possible. 842 // Allow constant expressions. 843 if (!A && !B) 844 return true; 845 // Allows aliases with zero offset. 846 if (Res.getConstant() == 0 && (!A || !B)) 847 return true; 848 } 849 } 850 851 Res = MCValue::get(SRE, nullptr, 0); 852 return true; 853 } 854 855 case Unary: { 856 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this); 857 MCValue Value; 858 859 if (!AUE->getSubExpr()->evaluateAsRelocatableImpl(Value, Asm, Layout, Fixup, 860 Addrs, InSet)) 861 return false; 862 863 switch (AUE->getOpcode()) { 864 case MCUnaryExpr::LNot: 865 if (!Value.isAbsolute()) 866 return false; 867 Res = MCValue::get(!Value.getConstant()); 868 break; 869 case MCUnaryExpr::Minus: 870 /// -(a - b + const) ==> (b - a - const) 871 if (Value.getSymA() && !Value.getSymB()) 872 return false; 873 874 // The cast avoids undefined behavior if the constant is INT64_MIN. 875 Res = MCValue::get(Value.getSymB(), Value.getSymA(), 876 -(uint64_t)Value.getConstant()); 877 break; 878 case MCUnaryExpr::Not: 879 if (!Value.isAbsolute()) 880 return false; 881 Res = MCValue::get(~Value.getConstant()); 882 break; 883 case MCUnaryExpr::Plus: 884 Res = Value; 885 break; 886 } 887 888 return true; 889 } 890 891 case Binary: { 892 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this); 893 MCValue LHSValue, RHSValue; 894 895 if (!ABE->getLHS()->evaluateAsRelocatableImpl(LHSValue, Asm, Layout, Fixup, 896 Addrs, InSet) || 897 !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup, 898 Addrs, InSet)) { 899 // Check if both are Target Expressions, see if we can compare them. 900 if (const MCTargetExpr *L = dyn_cast<MCTargetExpr>(ABE->getLHS())) 901 if (const MCTargetExpr *R = cast<MCTargetExpr>(ABE->getRHS())) { 902 switch (ABE->getOpcode()) { 903 case MCBinaryExpr::EQ: 904 Res = MCValue::get((L->isEqualTo(R)) ? -1 : 0); 905 return true; 906 case MCBinaryExpr::NE: 907 Res = MCValue::get((R->isEqualTo(R)) ? 0 : -1); 908 return true; 909 default: break; 910 } 911 } 912 return false; 913 } 914 915 // We only support a few operations on non-constant expressions, handle 916 // those first. 917 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) { 918 switch (ABE->getOpcode()) { 919 default: 920 return false; 921 case MCBinaryExpr::Sub: 922 // Negate RHS and add. 923 // The cast avoids undefined behavior if the constant is INT64_MIN. 924 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 925 RHSValue.getSymB(), RHSValue.getSymA(), 926 -(uint64_t)RHSValue.getConstant(), Res); 927 928 case MCBinaryExpr::Add: 929 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 930 RHSValue.getSymA(), RHSValue.getSymB(), 931 RHSValue.getConstant(), Res); 932 } 933 } 934 935 // FIXME: We need target hooks for the evaluation. It may be limited in 936 // width, and gas defines the result of comparisons differently from 937 // Apple as. 938 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant(); 939 int64_t Result = 0; 940 auto Op = ABE->getOpcode(); 941 switch (Op) { 942 case MCBinaryExpr::AShr: Result = LHS >> RHS; break; 943 case MCBinaryExpr::Add: Result = LHS + RHS; break; 944 case MCBinaryExpr::And: Result = LHS & RHS; break; 945 case MCBinaryExpr::Div: 946 case MCBinaryExpr::Mod: 947 // Handle division by zero. gas just emits a warning and keeps going, 948 // we try to be stricter. 949 // FIXME: Currently the caller of this function has no way to understand 950 // we're bailing out because of 'division by zero'. Therefore, it will 951 // emit a 'expected relocatable expression' error. It would be nice to 952 // change this code to emit a better diagnostic. 953 if (RHS == 0) 954 return false; 955 if (ABE->getOpcode() == MCBinaryExpr::Div) 956 Result = LHS / RHS; 957 else 958 Result = LHS % RHS; 959 break; 960 case MCBinaryExpr::EQ: Result = LHS == RHS; break; 961 case MCBinaryExpr::GT: Result = LHS > RHS; break; 962 case MCBinaryExpr::GTE: Result = LHS >= RHS; break; 963 case MCBinaryExpr::LAnd: Result = LHS && RHS; break; 964 case MCBinaryExpr::LOr: Result = LHS || RHS; break; 965 case MCBinaryExpr::LShr: Result = uint64_t(LHS) >> uint64_t(RHS); break; 966 case MCBinaryExpr::LT: Result = LHS < RHS; break; 967 case MCBinaryExpr::LTE: Result = LHS <= RHS; break; 968 case MCBinaryExpr::Mul: Result = LHS * RHS; break; 969 case MCBinaryExpr::NE: Result = LHS != RHS; break; 970 case MCBinaryExpr::Or: Result = LHS | RHS; break; 971 case MCBinaryExpr::OrNot: Result = LHS | ~RHS; break; 972 case MCBinaryExpr::Shl: Result = uint64_t(LHS) << uint64_t(RHS); break; 973 case MCBinaryExpr::Sub: Result = LHS - RHS; break; 974 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break; 975 } 976 977 switch (Op) { 978 default: 979 Res = MCValue::get(Result); 980 break; 981 case MCBinaryExpr::EQ: 982 case MCBinaryExpr::GT: 983 case MCBinaryExpr::GTE: 984 case MCBinaryExpr::LT: 985 case MCBinaryExpr::LTE: 986 case MCBinaryExpr::NE: 987 // A comparison operator returns a -1 if true and 0 if false. 988 Res = MCValue::get(Result ? -1 : 0); 989 break; 990 } 991 992 return true; 993 } 994 } 995 996 llvm_unreachable("Invalid assembly expression kind!"); 997 } 998 999 MCFragment *MCExpr::findAssociatedFragment() const { 1000 switch (getKind()) { 1001 case Target: 1002 // We never look through target specific expressions. 1003 return cast<MCTargetExpr>(this)->findAssociatedFragment(); 1004 1005 case Constant: 1006 return MCSymbol::AbsolutePseudoFragment; 1007 1008 case SymbolRef: { 1009 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 1010 const MCSymbol &Sym = SRE->getSymbol(); 1011 return Sym.getFragment(); 1012 } 1013 1014 case Unary: 1015 return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment(); 1016 1017 case Binary: { 1018 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this); 1019 MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment(); 1020 MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment(); 1021 1022 // If either is absolute, return the other. 1023 if (LHS_F == MCSymbol::AbsolutePseudoFragment) 1024 return RHS_F; 1025 if (RHS_F == MCSymbol::AbsolutePseudoFragment) 1026 return LHS_F; 1027 1028 // Not always correct, but probably the best we can do without more context. 1029 if (BE->getOpcode() == MCBinaryExpr::Sub) 1030 return MCSymbol::AbsolutePseudoFragment; 1031 1032 // Otherwise, return the first non-null fragment. 1033 return LHS_F ? LHS_F : RHS_F; 1034 } 1035 } 1036 1037 llvm_unreachable("Invalid assembly expression kind!"); 1038 } 1039