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