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_AVR_PM: return "pm"; 273 case VK_PPC_LO: return "l"; 274 case VK_PPC_HI: return "h"; 275 case VK_PPC_HA: return "ha"; 276 case VK_PPC_HIGH: return "high"; 277 case VK_PPC_HIGHA: return "higha"; 278 case VK_PPC_HIGHER: return "higher"; 279 case VK_PPC_HIGHERA: return "highera"; 280 case VK_PPC_HIGHEST: return "highest"; 281 case VK_PPC_HIGHESTA: return "highesta"; 282 case VK_PPC_GOT_LO: return "got@l"; 283 case VK_PPC_GOT_HI: return "got@h"; 284 case VK_PPC_GOT_HA: return "got@ha"; 285 case VK_PPC_TOCBASE: return "tocbase"; 286 case VK_PPC_TOC: return "toc"; 287 case VK_PPC_TOC_LO: return "toc@l"; 288 case VK_PPC_TOC_HI: return "toc@h"; 289 case VK_PPC_TOC_HA: return "toc@ha"; 290 case VK_PPC_U: return "u"; 291 case VK_PPC_L: return "l"; 292 case VK_PPC_DTPMOD: return "dtpmod"; 293 case VK_PPC_TPREL_LO: return "tprel@l"; 294 case VK_PPC_TPREL_HI: return "tprel@h"; 295 case VK_PPC_TPREL_HA: return "tprel@ha"; 296 case VK_PPC_TPREL_HIGH: return "tprel@high"; 297 case VK_PPC_TPREL_HIGHA: return "tprel@higha"; 298 case VK_PPC_TPREL_HIGHER: return "tprel@higher"; 299 case VK_PPC_TPREL_HIGHERA: return "tprel@highera"; 300 case VK_PPC_TPREL_HIGHEST: return "tprel@highest"; 301 case VK_PPC_TPREL_HIGHESTA: return "tprel@highesta"; 302 case VK_PPC_DTPREL_LO: return "dtprel@l"; 303 case VK_PPC_DTPREL_HI: return "dtprel@h"; 304 case VK_PPC_DTPREL_HA: return "dtprel@ha"; 305 case VK_PPC_DTPREL_HIGH: return "dtprel@high"; 306 case VK_PPC_DTPREL_HIGHA: return "dtprel@higha"; 307 case VK_PPC_DTPREL_HIGHER: return "dtprel@higher"; 308 case VK_PPC_DTPREL_HIGHERA: return "dtprel@highera"; 309 case VK_PPC_DTPREL_HIGHEST: return "dtprel@highest"; 310 case VK_PPC_DTPREL_HIGHESTA: return "dtprel@highesta"; 311 case VK_PPC_GOT_TPREL: return "got@tprel"; 312 case VK_PPC_GOT_TPREL_LO: return "got@tprel@l"; 313 case VK_PPC_GOT_TPREL_HI: return "got@tprel@h"; 314 case VK_PPC_GOT_TPREL_HA: return "got@tprel@ha"; 315 case VK_PPC_GOT_DTPREL: return "got@dtprel"; 316 case VK_PPC_GOT_DTPREL_LO: return "got@dtprel@l"; 317 case VK_PPC_GOT_DTPREL_HI: return "got@dtprel@h"; 318 case VK_PPC_GOT_DTPREL_HA: return "got@dtprel@ha"; 319 case VK_PPC_TLS: return "tls"; 320 case VK_PPC_GOT_TLSGD: return "got@tlsgd"; 321 case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l"; 322 case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h"; 323 case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha"; 324 case VK_PPC_TLSGD: return "tlsgd"; 325 case VK_PPC_AIX_TLSGD: 326 return "gd"; 327 case VK_PPC_AIX_TLSGDM: 328 return "m"; 329 case VK_PPC_GOT_TLSLD: return "got@tlsld"; 330 case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l"; 331 case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h"; 332 case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha"; 333 case VK_PPC_GOT_PCREL: 334 return "got@pcrel"; 335 case VK_PPC_GOT_TLSGD_PCREL: 336 return "got@tlsgd@pcrel"; 337 case VK_PPC_GOT_TLSLD_PCREL: 338 return "got@tlsld@pcrel"; 339 case VK_PPC_GOT_TPREL_PCREL: 340 return "got@tprel@pcrel"; 341 case VK_PPC_TLS_PCREL: 342 return "tls@pcrel"; 343 case VK_PPC_TLSLD: return "tlsld"; 344 case VK_PPC_LOCAL: return "local"; 345 case VK_PPC_NOTOC: return "notoc"; 346 case VK_PPC_PCREL_OPT: return "<<invalid>>"; 347 case VK_COFF_IMGREL32: return "IMGREL"; 348 case VK_Hexagon_LO16: return "LO16"; 349 case VK_Hexagon_HI16: return "HI16"; 350 case VK_Hexagon_GPREL: return "GPREL"; 351 case VK_Hexagon_GD_GOT: return "GDGOT"; 352 case VK_Hexagon_LD_GOT: return "LDGOT"; 353 case VK_Hexagon_GD_PLT: return "GDPLT"; 354 case VK_Hexagon_LD_PLT: return "LDPLT"; 355 case VK_Hexagon_IE: return "IE"; 356 case VK_Hexagon_IE_GOT: return "IEGOT"; 357 case VK_WASM_TYPEINDEX: return "TYPEINDEX"; 358 case VK_WASM_MBREL: return "MBREL"; 359 case VK_WASM_TLSREL: return "TLSREL"; 360 case VK_WASM_TBREL: return "TBREL"; 361 case VK_AMDGPU_GOTPCREL32_LO: return "gotpcrel32@lo"; 362 case VK_AMDGPU_GOTPCREL32_HI: return "gotpcrel32@hi"; 363 case VK_AMDGPU_REL32_LO: return "rel32@lo"; 364 case VK_AMDGPU_REL32_HI: return "rel32@hi"; 365 case VK_AMDGPU_REL64: return "rel64"; 366 case VK_AMDGPU_ABS32_LO: return "abs32@lo"; 367 case VK_AMDGPU_ABS32_HI: return "abs32@hi"; 368 case VK_VE_HI32: return "hi"; 369 case VK_VE_LO32: return "lo"; 370 case VK_VE_PC_HI32: return "pc_hi"; 371 case VK_VE_PC_LO32: return "pc_lo"; 372 case VK_VE_GOT_HI32: return "got_hi"; 373 case VK_VE_GOT_LO32: return "got_lo"; 374 case VK_VE_GOTOFF_HI32: return "gotoff_hi"; 375 case VK_VE_GOTOFF_LO32: return "gotoff_lo"; 376 case VK_VE_PLT_HI32: return "plt_hi"; 377 case VK_VE_PLT_LO32: return "plt_lo"; 378 case VK_VE_TLS_GD_HI32: return "tls_gd_hi"; 379 case VK_VE_TLS_GD_LO32: return "tls_gd_lo"; 380 case VK_VE_TPOFF_HI32: return "tpoff_hi"; 381 case VK_VE_TPOFF_LO32: return "tpoff_lo"; 382 } 383 llvm_unreachable("Invalid variant kind"); 384 } 385 386 MCSymbolRefExpr::VariantKind 387 MCSymbolRefExpr::getVariantKindForName(StringRef Name) { 388 return StringSwitch<VariantKind>(Name.lower()) 389 .Case("dtprel", VK_DTPREL) 390 .Case("dtpoff", VK_DTPOFF) 391 .Case("got", VK_GOT) 392 .Case("gotoff", VK_GOTOFF) 393 .Case("gotrel", VK_GOTREL) 394 .Case("pcrel", VK_PCREL) 395 .Case("gotpcrel", VK_GOTPCREL) 396 .Case("gottpoff", VK_GOTTPOFF) 397 .Case("indntpoff", VK_INDNTPOFF) 398 .Case("ntpoff", VK_NTPOFF) 399 .Case("gotntpoff", VK_GOTNTPOFF) 400 .Case("plt", VK_PLT) 401 .Case("tlscall", VK_TLSCALL) 402 .Case("tlsdesc", VK_TLSDESC) 403 .Case("tlsgd", VK_TLSGD) 404 .Case("tlsld", VK_TLSLD) 405 .Case("tlsldm", VK_TLSLDM) 406 .Case("tpoff", VK_TPOFF) 407 .Case("tprel", VK_TPREL) 408 .Case("tlvp", VK_TLVP) 409 .Case("tlvppage", VK_TLVPPAGE) 410 .Case("tlvppageoff", VK_TLVPPAGEOFF) 411 .Case("page", VK_PAGE) 412 .Case("pageoff", VK_PAGEOFF) 413 .Case("gotpage", VK_GOTPAGE) 414 .Case("gotpageoff", VK_GOTPAGEOFF) 415 .Case("imgrel", VK_COFF_IMGREL32) 416 .Case("secrel32", VK_SECREL) 417 .Case("size", VK_SIZE) 418 .Case("abs8", VK_X86_ABS8) 419 .Case("pltoff", VK_X86_PLTOFF) 420 .Case("l", VK_PPC_LO) 421 .Case("h", VK_PPC_HI) 422 .Case("ha", VK_PPC_HA) 423 .Case("high", VK_PPC_HIGH) 424 .Case("higha", VK_PPC_HIGHA) 425 .Case("higher", VK_PPC_HIGHER) 426 .Case("highera", VK_PPC_HIGHERA) 427 .Case("highest", VK_PPC_HIGHEST) 428 .Case("highesta", VK_PPC_HIGHESTA) 429 .Case("got@l", VK_PPC_GOT_LO) 430 .Case("got@h", VK_PPC_GOT_HI) 431 .Case("got@ha", VK_PPC_GOT_HA) 432 .Case("local", VK_PPC_LOCAL) 433 .Case("tocbase", VK_PPC_TOCBASE) 434 .Case("toc", VK_PPC_TOC) 435 .Case("toc@l", VK_PPC_TOC_LO) 436 .Case("toc@h", VK_PPC_TOC_HI) 437 .Case("toc@ha", VK_PPC_TOC_HA) 438 .Case("u", VK_PPC_U) 439 .Case("l", VK_PPC_L) 440 .Case("tls", VK_PPC_TLS) 441 .Case("dtpmod", VK_PPC_DTPMOD) 442 .Case("tprel@l", VK_PPC_TPREL_LO) 443 .Case("tprel@h", VK_PPC_TPREL_HI) 444 .Case("tprel@ha", VK_PPC_TPREL_HA) 445 .Case("tprel@high", VK_PPC_TPREL_HIGH) 446 .Case("tprel@higha", VK_PPC_TPREL_HIGHA) 447 .Case("tprel@higher", VK_PPC_TPREL_HIGHER) 448 .Case("tprel@highera", VK_PPC_TPREL_HIGHERA) 449 .Case("tprel@highest", VK_PPC_TPREL_HIGHEST) 450 .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA) 451 .Case("dtprel@l", VK_PPC_DTPREL_LO) 452 .Case("dtprel@h", VK_PPC_DTPREL_HI) 453 .Case("dtprel@ha", VK_PPC_DTPREL_HA) 454 .Case("dtprel@high", VK_PPC_DTPREL_HIGH) 455 .Case("dtprel@higha", VK_PPC_DTPREL_HIGHA) 456 .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER) 457 .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA) 458 .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST) 459 .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA) 460 .Case("got@tprel", VK_PPC_GOT_TPREL) 461 .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO) 462 .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI) 463 .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA) 464 .Case("got@dtprel", VK_PPC_GOT_DTPREL) 465 .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO) 466 .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI) 467 .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA) 468 .Case("got@tlsgd", VK_PPC_GOT_TLSGD) 469 .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO) 470 .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI) 471 .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA) 472 .Case("got@tlsld", VK_PPC_GOT_TLSLD) 473 .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO) 474 .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI) 475 .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA) 476 .Case("got@pcrel", VK_PPC_GOT_PCREL) 477 .Case("got@tlsgd@pcrel", VK_PPC_GOT_TLSGD_PCREL) 478 .Case("got@tlsld@pcrel", VK_PPC_GOT_TLSLD_PCREL) 479 .Case("got@tprel@pcrel", VK_PPC_GOT_TPREL_PCREL) 480 .Case("tls@pcrel", VK_PPC_TLS_PCREL) 481 .Case("notoc", VK_PPC_NOTOC) 482 .Case("gdgot", VK_Hexagon_GD_GOT) 483 .Case("gdplt", VK_Hexagon_GD_PLT) 484 .Case("iegot", VK_Hexagon_IE_GOT) 485 .Case("ie", VK_Hexagon_IE) 486 .Case("ldgot", VK_Hexagon_LD_GOT) 487 .Case("ldplt", VK_Hexagon_LD_PLT) 488 .Case("none", VK_ARM_NONE) 489 .Case("got_prel", VK_ARM_GOT_PREL) 490 .Case("target1", VK_ARM_TARGET1) 491 .Case("target2", VK_ARM_TARGET2) 492 .Case("prel31", VK_ARM_PREL31) 493 .Case("sbrel", VK_ARM_SBREL) 494 .Case("tlsldo", VK_ARM_TLSLDO) 495 .Case("lo8", VK_AVR_LO8) 496 .Case("hi8", VK_AVR_HI8) 497 .Case("hlo8", VK_AVR_HLO8) 498 .Case("typeindex", VK_WASM_TYPEINDEX) 499 .Case("tbrel", VK_WASM_TBREL) 500 .Case("mbrel", VK_WASM_MBREL) 501 .Case("tlsrel", VK_WASM_TLSREL) 502 .Case("gotpcrel32@lo", VK_AMDGPU_GOTPCREL32_LO) 503 .Case("gotpcrel32@hi", VK_AMDGPU_GOTPCREL32_HI) 504 .Case("rel32@lo", VK_AMDGPU_REL32_LO) 505 .Case("rel32@hi", VK_AMDGPU_REL32_HI) 506 .Case("rel64", VK_AMDGPU_REL64) 507 .Case("abs32@lo", VK_AMDGPU_ABS32_LO) 508 .Case("abs32@hi", VK_AMDGPU_ABS32_HI) 509 .Case("hi", VK_VE_HI32) 510 .Case("lo", VK_VE_LO32) 511 .Case("pc_hi", VK_VE_PC_HI32) 512 .Case("pc_lo", VK_VE_PC_LO32) 513 .Case("got_hi", VK_VE_GOT_HI32) 514 .Case("got_lo", VK_VE_GOT_LO32) 515 .Case("gotoff_hi", VK_VE_GOTOFF_HI32) 516 .Case("gotoff_lo", VK_VE_GOTOFF_LO32) 517 .Case("plt_hi", VK_VE_PLT_HI32) 518 .Case("plt_lo", VK_VE_PLT_LO32) 519 .Case("tls_gd_hi", VK_VE_TLS_GD_HI32) 520 .Case("tls_gd_lo", VK_VE_TLS_GD_LO32) 521 .Case("tpoff_hi", VK_VE_TPOFF_HI32) 522 .Case("tpoff_lo", VK_VE_TPOFF_LO32) 523 .Default(VK_Invalid); 524 } 525 526 /* *** */ 527 528 void MCTargetExpr::anchor() {} 529 530 /* *** */ 531 532 bool MCExpr::evaluateAsAbsolute(int64_t &Res) const { 533 return evaluateAsAbsolute(Res, nullptr, nullptr, nullptr, false); 534 } 535 536 bool MCExpr::evaluateAsAbsolute(int64_t &Res, 537 const MCAsmLayout &Layout) const { 538 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr, false); 539 } 540 541 bool MCExpr::evaluateAsAbsolute(int64_t &Res, 542 const MCAsmLayout &Layout, 543 const SectionAddrMap &Addrs) const { 544 // Setting InSet causes us to absolutize differences across sections and that 545 // is what the MachO writer uses Addrs for. 546 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs, true); 547 } 548 549 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const { 550 return evaluateAsAbsolute(Res, &Asm, nullptr, nullptr, false); 551 } 552 553 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm) const { 554 return evaluateAsAbsolute(Res, Asm, nullptr, nullptr, false); 555 } 556 557 bool MCExpr::evaluateKnownAbsolute(int64_t &Res, 558 const MCAsmLayout &Layout) const { 559 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr, 560 true); 561 } 562 563 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, 564 const MCAsmLayout *Layout, 565 const SectionAddrMap *Addrs, bool InSet) const { 566 MCValue Value; 567 568 // Fast path constants. 569 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) { 570 Res = CE->getValue(); 571 return true; 572 } 573 574 bool IsRelocatable = 575 evaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs, InSet); 576 577 // Record the current value. 578 Res = Value.getConstant(); 579 580 return IsRelocatable && Value.isAbsolute(); 581 } 582 583 /// Helper method for \see EvaluateSymbolAdd(). 584 static void AttemptToFoldSymbolOffsetDifference( 585 const MCAssembler *Asm, const MCAsmLayout *Layout, 586 const SectionAddrMap *Addrs, bool InSet, const MCSymbolRefExpr *&A, 587 const MCSymbolRefExpr *&B, int64_t &Addend) { 588 if (!A || !B) 589 return; 590 591 const MCSymbol &SA = A->getSymbol(); 592 const MCSymbol &SB = B->getSymbol(); 593 594 if (SA.isUndefined() || SB.isUndefined()) 595 return; 596 597 if (!Asm->getWriter().isSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet)) 598 return; 599 600 auto FinalizeFolding = [&]() { 601 // Pointers to Thumb symbols need to have their low-bit set to allow 602 // for interworking. 603 if (Asm->isThumbFunc(&SA)) 604 Addend |= 1; 605 606 // If symbol is labeled as micromips, we set low-bit to ensure 607 // correct offset in .gcc_except_table 608 if (Asm->getBackend().isMicroMips(&SA)) 609 Addend |= 1; 610 611 // Clear the symbol expr pointers to indicate we have folded these 612 // operands. 613 A = B = nullptr; 614 }; 615 616 const MCFragment *FA = SA.getFragment(); 617 const MCFragment *FB = SB.getFragment(); 618 // If both symbols are in the same fragment, return the difference of their 619 // offsets 620 if (FA == FB && !SA.isVariable() && !SA.isUnset() && !SB.isVariable() && 621 !SB.isUnset()) { 622 Addend += SA.getOffset() - SB.getOffset(); 623 return FinalizeFolding(); 624 } 625 626 const MCSection &SecA = *FA->getParent(); 627 const MCSection &SecB = *FB->getParent(); 628 629 if ((&SecA != &SecB) && !Addrs) 630 return; 631 632 if (Layout) { 633 // One of the symbol involved is part of a fragment being laid out. Quit now 634 // to avoid a self loop. 635 if (!Layout->canGetFragmentOffset(FA) || !Layout->canGetFragmentOffset(FB)) 636 return; 637 638 // Eagerly evaluate when layout is finalized. 639 Addend += Layout->getSymbolOffset(A->getSymbol()) - 640 Layout->getSymbolOffset(B->getSymbol()); 641 if (Addrs && (&SecA != &SecB)) 642 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB)); 643 644 FinalizeFolding(); 645 } else { 646 // When layout is not finalized, our ability to resolve differences between 647 // symbols is limited to specific cases where the fragments between two 648 // symbols (including the fragments the symbols are defined in) are 649 // fixed-size fragments so the difference can be calculated. For example, 650 // this is important when the Subtarget is changed and a new MCDataFragment 651 // is created in the case of foo: instr; .arch_extension ext; instr .if . - 652 // foo. 653 if (SA.isVariable() || SA.isUnset() || SB.isVariable() || SB.isUnset() || 654 FA->getKind() != MCFragment::FT_Data || 655 FB->getKind() != MCFragment::FT_Data || 656 FA->getSubsectionNumber() != FB->getSubsectionNumber()) 657 return; 658 // Try to find a constant displacement from FA to FB, add the displacement 659 // between the offset in FA of SA and the offset in FB of SB. 660 int64_t Displacement = SA.getOffset() - SB.getOffset(); 661 for (auto FI = FB->getIterator(), FE = SecA.end(); FI != FE; ++FI) { 662 if (&*FI == FA) { 663 Addend += Displacement; 664 return FinalizeFolding(); 665 } 666 667 if (FI->getKind() != MCFragment::FT_Data) 668 return; 669 Displacement += cast<MCDataFragment>(FI)->getContents().size(); 670 } 671 } 672 } 673 674 /// Evaluate the result of an add between (conceptually) two MCValues. 675 /// 676 /// This routine conceptually attempts to construct an MCValue: 677 /// Result = (Result_A - Result_B + Result_Cst) 678 /// from two MCValue's LHS and RHS where 679 /// Result = LHS + RHS 680 /// and 681 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 682 /// 683 /// This routine attempts to aggressively fold the operands such that the result 684 /// is representable in an MCValue, but may not always succeed. 685 /// 686 /// \returns True on success, false if the result is not representable in an 687 /// MCValue. 688 689 /// NOTE: It is really important to have both the Asm and Layout arguments. 690 /// They might look redundant, but this function can be used before layout 691 /// is done (see the object streamer for example) and having the Asm argument 692 /// lets us avoid relaxations early. 693 static bool 694 EvaluateSymbolicAdd(const MCAssembler *Asm, const MCAsmLayout *Layout, 695 const SectionAddrMap *Addrs, bool InSet, const MCValue &LHS, 696 const MCSymbolRefExpr *RHS_A, const MCSymbolRefExpr *RHS_B, 697 int64_t RHS_Cst, MCValue &Res) { 698 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy 699 // about dealing with modifiers. This will ultimately bite us, one day. 700 const MCSymbolRefExpr *LHS_A = LHS.getSymA(); 701 const MCSymbolRefExpr *LHS_B = LHS.getSymB(); 702 int64_t LHS_Cst = LHS.getConstant(); 703 704 // Fold the result constant immediately. 705 int64_t Result_Cst = LHS_Cst + RHS_Cst; 706 707 assert((!Layout || Asm) && 708 "Must have an assembler object if layout is given!"); 709 710 // If we have a layout, we can fold resolved differences. 711 if (Asm) { 712 // First, fold out any differences which are fully resolved. By 713 // reassociating terms in 714 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 715 // we have the four possible differences: 716 // (LHS_A - LHS_B), 717 // (LHS_A - RHS_B), 718 // (RHS_A - LHS_B), 719 // (RHS_A - RHS_B). 720 // Since we are attempting to be as aggressive as possible about folding, we 721 // attempt to evaluate each possible alternative. 722 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B, 723 Result_Cst); 724 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B, 725 Result_Cst); 726 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B, 727 Result_Cst); 728 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B, 729 Result_Cst); 730 } 731 732 // We can't represent the addition or subtraction of two symbols. 733 if ((LHS_A && RHS_A) || (LHS_B && RHS_B)) 734 return false; 735 736 // At this point, we have at most one additive symbol and one subtractive 737 // symbol -- find them. 738 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A; 739 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B; 740 741 Res = MCValue::get(A, B, Result_Cst); 742 return true; 743 } 744 745 bool MCExpr::evaluateAsRelocatable(MCValue &Res, 746 const MCAsmLayout *Layout, 747 const MCFixup *Fixup) const { 748 MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr; 749 return evaluateAsRelocatableImpl(Res, Assembler, Layout, Fixup, nullptr, 750 false); 751 } 752 753 bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const { 754 MCAssembler *Assembler = &Layout.getAssembler(); 755 return evaluateAsRelocatableImpl(Res, Assembler, &Layout, nullptr, nullptr, 756 true); 757 } 758 759 static bool canExpand(const MCSymbol &Sym, bool InSet) { 760 const MCExpr *Expr = Sym.getVariableValue(); 761 const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr); 762 if (Inner) { 763 if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF) 764 return false; 765 } 766 767 if (InSet) 768 return true; 769 return !Sym.isInSection(); 770 } 771 772 bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm, 773 const MCAsmLayout *Layout, 774 const MCFixup *Fixup, 775 const SectionAddrMap *Addrs, 776 bool InSet) const { 777 ++stats::MCExprEvaluate; 778 779 switch (getKind()) { 780 case Target: 781 return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Layout, 782 Fixup); 783 784 case Constant: 785 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue()); 786 return true; 787 788 case SymbolRef: { 789 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 790 const MCSymbol &Sym = SRE->getSymbol(); 791 const auto Kind = SRE->getKind(); 792 793 // Evaluate recursively if this is a variable. 794 if (Sym.isVariable() && (Kind == MCSymbolRefExpr::VK_None || Layout) && 795 canExpand(Sym, InSet)) { 796 bool IsMachO = SRE->hasSubsectionsViaSymbols(); 797 if (Sym.getVariableValue()->evaluateAsRelocatableImpl( 798 Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO)) { 799 if (Kind != MCSymbolRefExpr::VK_None) { 800 if (Res.isAbsolute()) { 801 Res = MCValue::get(SRE, nullptr, 0); 802 return true; 803 } 804 // If the reference has a variant kind, we can only handle expressions 805 // which evaluate exactly to a single unadorned symbol. Attach the 806 // original VariantKind to SymA of the result. 807 if (Res.getRefKind() != MCSymbolRefExpr::VK_None || !Res.getSymA() || 808 Res.getSymB() || Res.getConstant()) 809 return false; 810 Res = 811 MCValue::get(MCSymbolRefExpr::create(&Res.getSymA()->getSymbol(), 812 Kind, Asm->getContext()), 813 Res.getSymB(), Res.getConstant(), Res.getRefKind()); 814 } 815 if (!IsMachO) 816 return true; 817 818 const MCSymbolRefExpr *A = Res.getSymA(); 819 const MCSymbolRefExpr *B = Res.getSymB(); 820 // FIXME: This is small hack. Given 821 // a = b + 4 822 // .long a 823 // the OS X assembler will completely drop the 4. We should probably 824 // include it in the relocation or produce an error if that is not 825 // possible. 826 // Allow constant expressions. 827 if (!A && !B) 828 return true; 829 // Allows aliases with zero offset. 830 if (Res.getConstant() == 0 && (!A || !B)) 831 return true; 832 } 833 } 834 835 Res = MCValue::get(SRE, nullptr, 0); 836 return true; 837 } 838 839 case Unary: { 840 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this); 841 MCValue Value; 842 843 if (!AUE->getSubExpr()->evaluateAsRelocatableImpl(Value, Asm, Layout, Fixup, 844 Addrs, InSet)) 845 return false; 846 847 switch (AUE->getOpcode()) { 848 case MCUnaryExpr::LNot: 849 if (!Value.isAbsolute()) 850 return false; 851 Res = MCValue::get(!Value.getConstant()); 852 break; 853 case MCUnaryExpr::Minus: 854 /// -(a - b + const) ==> (b - a - const) 855 if (Value.getSymA() && !Value.getSymB()) 856 return false; 857 858 // The cast avoids undefined behavior if the constant is INT64_MIN. 859 Res = MCValue::get(Value.getSymB(), Value.getSymA(), 860 -(uint64_t)Value.getConstant()); 861 break; 862 case MCUnaryExpr::Not: 863 if (!Value.isAbsolute()) 864 return false; 865 Res = MCValue::get(~Value.getConstant()); 866 break; 867 case MCUnaryExpr::Plus: 868 Res = Value; 869 break; 870 } 871 872 return true; 873 } 874 875 case Binary: { 876 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this); 877 MCValue LHSValue, RHSValue; 878 879 if (!ABE->getLHS()->evaluateAsRelocatableImpl(LHSValue, Asm, Layout, Fixup, 880 Addrs, InSet) || 881 !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup, 882 Addrs, InSet)) { 883 // Check if both are Target Expressions, see if we can compare them. 884 if (const MCTargetExpr *L = dyn_cast<MCTargetExpr>(ABE->getLHS())) 885 if (const MCTargetExpr *R = cast<MCTargetExpr>(ABE->getRHS())) { 886 switch (ABE->getOpcode()) { 887 case MCBinaryExpr::EQ: 888 Res = MCValue::get((L->isEqualTo(R)) ? -1 : 0); 889 return true; 890 case MCBinaryExpr::NE: 891 Res = MCValue::get((R->isEqualTo(R)) ? 0 : -1); 892 return true; 893 default: break; 894 } 895 } 896 return false; 897 } 898 899 // We only support a few operations on non-constant expressions, handle 900 // those first. 901 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) { 902 switch (ABE->getOpcode()) { 903 default: 904 return false; 905 case MCBinaryExpr::Sub: 906 // Negate RHS and add. 907 // The cast avoids undefined behavior if the constant is INT64_MIN. 908 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 909 RHSValue.getSymB(), RHSValue.getSymA(), 910 -(uint64_t)RHSValue.getConstant(), Res); 911 912 case MCBinaryExpr::Add: 913 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 914 RHSValue.getSymA(), RHSValue.getSymB(), 915 RHSValue.getConstant(), Res); 916 } 917 } 918 919 // FIXME: We need target hooks for the evaluation. It may be limited in 920 // width, and gas defines the result of comparisons differently from 921 // Apple as. 922 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant(); 923 int64_t Result = 0; 924 auto Op = ABE->getOpcode(); 925 switch (Op) { 926 case MCBinaryExpr::AShr: Result = LHS >> RHS; break; 927 case MCBinaryExpr::Add: Result = LHS + RHS; break; 928 case MCBinaryExpr::And: Result = LHS & RHS; break; 929 case MCBinaryExpr::Div: 930 case MCBinaryExpr::Mod: 931 // Handle division by zero. gas just emits a warning and keeps going, 932 // we try to be stricter. 933 // FIXME: Currently the caller of this function has no way to understand 934 // we're bailing out because of 'division by zero'. Therefore, it will 935 // emit a 'expected relocatable expression' error. It would be nice to 936 // change this code to emit a better diagnostic. 937 if (RHS == 0) 938 return false; 939 if (ABE->getOpcode() == MCBinaryExpr::Div) 940 Result = LHS / RHS; 941 else 942 Result = LHS % RHS; 943 break; 944 case MCBinaryExpr::EQ: Result = LHS == RHS; break; 945 case MCBinaryExpr::GT: Result = LHS > RHS; break; 946 case MCBinaryExpr::GTE: Result = LHS >= RHS; break; 947 case MCBinaryExpr::LAnd: Result = LHS && RHS; break; 948 case MCBinaryExpr::LOr: Result = LHS || RHS; break; 949 case MCBinaryExpr::LShr: Result = uint64_t(LHS) >> uint64_t(RHS); break; 950 case MCBinaryExpr::LT: Result = LHS < RHS; break; 951 case MCBinaryExpr::LTE: Result = LHS <= RHS; break; 952 case MCBinaryExpr::Mul: Result = LHS * RHS; break; 953 case MCBinaryExpr::NE: Result = LHS != RHS; break; 954 case MCBinaryExpr::Or: Result = LHS | RHS; break; 955 case MCBinaryExpr::OrNot: Result = LHS | ~RHS; break; 956 case MCBinaryExpr::Shl: Result = uint64_t(LHS) << uint64_t(RHS); break; 957 case MCBinaryExpr::Sub: Result = LHS - RHS; break; 958 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break; 959 } 960 961 switch (Op) { 962 default: 963 Res = MCValue::get(Result); 964 break; 965 case MCBinaryExpr::EQ: 966 case MCBinaryExpr::GT: 967 case MCBinaryExpr::GTE: 968 case MCBinaryExpr::LT: 969 case MCBinaryExpr::LTE: 970 case MCBinaryExpr::NE: 971 // A comparison operator returns a -1 if true and 0 if false. 972 Res = MCValue::get(Result ? -1 : 0); 973 break; 974 } 975 976 return true; 977 } 978 } 979 980 llvm_unreachable("Invalid assembly expression kind!"); 981 } 982 983 MCFragment *MCExpr::findAssociatedFragment() const { 984 switch (getKind()) { 985 case Target: 986 // We never look through target specific expressions. 987 return cast<MCTargetExpr>(this)->findAssociatedFragment(); 988 989 case Constant: 990 return MCSymbol::AbsolutePseudoFragment; 991 992 case SymbolRef: { 993 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 994 const MCSymbol &Sym = SRE->getSymbol(); 995 return Sym.getFragment(); 996 } 997 998 case Unary: 999 return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment(); 1000 1001 case Binary: { 1002 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this); 1003 MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment(); 1004 MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment(); 1005 1006 // If either is absolute, return the other. 1007 if (LHS_F == MCSymbol::AbsolutePseudoFragment) 1008 return RHS_F; 1009 if (RHS_F == MCSymbol::AbsolutePseudoFragment) 1010 return LHS_F; 1011 1012 // Not always correct, but probably the best we can do without more context. 1013 if (BE->getOpcode() == MCBinaryExpr::Sub) 1014 return MCSymbol::AbsolutePseudoFragment; 1015 1016 // Otherwise, return the first non-null fragment. 1017 return LHS_F ? LHS_F : RHS_F; 1018 } 1019 } 1020 1021 llvm_unreachable("Invalid assembly expression kind!"); 1022 } 1023