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_GLOBAL: return "GLOBAL"; 308 case VK_WebAssembly_TYPEINDEX: return "TYPEINDEX"; 309 case VK_WebAssembly_EVENT: return "EVENT"; 310 case VK_AMDGPU_GOTPCREL32_LO: return "gotpcrel32@lo"; 311 case VK_AMDGPU_GOTPCREL32_HI: return "gotpcrel32@hi"; 312 case VK_AMDGPU_REL32_LO: return "rel32@lo"; 313 case VK_AMDGPU_REL32_HI: return "rel32@hi"; 314 case VK_AMDGPU_REL64: return "rel64"; 315 } 316 llvm_unreachable("Invalid variant kind"); 317 } 318 319 MCSymbolRefExpr::VariantKind 320 MCSymbolRefExpr::getVariantKindForName(StringRef Name) { 321 return StringSwitch<VariantKind>(Name.lower()) 322 .Case("dtprel", VK_DTPREL) 323 .Case("dtpoff", VK_DTPOFF) 324 .Case("got", VK_GOT) 325 .Case("gotoff", VK_GOTOFF) 326 .Case("gotrel", VK_GOTREL) 327 .Case("gotpcrel", VK_GOTPCREL) 328 .Case("gottpoff", VK_GOTTPOFF) 329 .Case("indntpoff", VK_INDNTPOFF) 330 .Case("ntpoff", VK_NTPOFF) 331 .Case("gotntpoff", VK_GOTNTPOFF) 332 .Case("plt", VK_PLT) 333 .Case("tlscall", VK_TLSCALL) 334 .Case("tlsdesc", VK_TLSDESC) 335 .Case("tlsgd", VK_TLSGD) 336 .Case("tlsld", VK_TLSLD) 337 .Case("tlsldm", VK_TLSLDM) 338 .Case("tpoff", VK_TPOFF) 339 .Case("tprel", VK_TPREL) 340 .Case("tlvp", VK_TLVP) 341 .Case("tlvppage", VK_TLVPPAGE) 342 .Case("tlvppageoff", VK_TLVPPAGEOFF) 343 .Case("page", VK_PAGE) 344 .Case("pageoff", VK_PAGEOFF) 345 .Case("gotpage", VK_GOTPAGE) 346 .Case("gotpageoff", VK_GOTPAGEOFF) 347 .Case("imgrel", VK_COFF_IMGREL32) 348 .Case("secrel32", VK_SECREL) 349 .Case("size", VK_SIZE) 350 .Case("abs8", VK_X86_ABS8) 351 .Case("l", VK_PPC_LO) 352 .Case("h", VK_PPC_HI) 353 .Case("ha", VK_PPC_HA) 354 .Case("high", VK_PPC_HIGH) 355 .Case("higha", VK_PPC_HIGHA) 356 .Case("higher", VK_PPC_HIGHER) 357 .Case("highera", VK_PPC_HIGHERA) 358 .Case("highest", VK_PPC_HIGHEST) 359 .Case("highesta", VK_PPC_HIGHESTA) 360 .Case("got@l", VK_PPC_GOT_LO) 361 .Case("got@h", VK_PPC_GOT_HI) 362 .Case("got@ha", VK_PPC_GOT_HA) 363 .Case("local", VK_PPC_LOCAL) 364 .Case("tocbase", VK_PPC_TOCBASE) 365 .Case("toc", VK_PPC_TOC) 366 .Case("toc@l", VK_PPC_TOC_LO) 367 .Case("toc@h", VK_PPC_TOC_HI) 368 .Case("toc@ha", VK_PPC_TOC_HA) 369 .Case("tls", VK_PPC_TLS) 370 .Case("dtpmod", VK_PPC_DTPMOD) 371 .Case("tprel@l", VK_PPC_TPREL_LO) 372 .Case("tprel@h", VK_PPC_TPREL_HI) 373 .Case("tprel@ha", VK_PPC_TPREL_HA) 374 .Case("tprel@high", VK_PPC_TPREL_HIGH) 375 .Case("tprel@higha", VK_PPC_TPREL_HIGHA) 376 .Case("tprel@higher", VK_PPC_TPREL_HIGHER) 377 .Case("tprel@highera", VK_PPC_TPREL_HIGHERA) 378 .Case("tprel@highest", VK_PPC_TPREL_HIGHEST) 379 .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA) 380 .Case("dtprel@l", VK_PPC_DTPREL_LO) 381 .Case("dtprel@h", VK_PPC_DTPREL_HI) 382 .Case("dtprel@ha", VK_PPC_DTPREL_HA) 383 .Case("dtprel@high", VK_PPC_DTPREL_HIGH) 384 .Case("dtprel@higha", VK_PPC_DTPREL_HIGHA) 385 .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER) 386 .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA) 387 .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST) 388 .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA) 389 .Case("got@tprel", VK_PPC_GOT_TPREL) 390 .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO) 391 .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI) 392 .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA) 393 .Case("got@dtprel", VK_PPC_GOT_DTPREL) 394 .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO) 395 .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI) 396 .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA) 397 .Case("got@tlsgd", VK_PPC_GOT_TLSGD) 398 .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO) 399 .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI) 400 .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA) 401 .Case("got@tlsld", VK_PPC_GOT_TLSLD) 402 .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO) 403 .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI) 404 .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA) 405 .Case("gdgot", VK_Hexagon_GD_GOT) 406 .Case("gdplt", VK_Hexagon_GD_PLT) 407 .Case("iegot", VK_Hexagon_IE_GOT) 408 .Case("ie", VK_Hexagon_IE) 409 .Case("ldgot", VK_Hexagon_LD_GOT) 410 .Case("ldplt", VK_Hexagon_LD_PLT) 411 .Case("pcrel", VK_Hexagon_PCREL) 412 .Case("none", VK_ARM_NONE) 413 .Case("got_prel", VK_ARM_GOT_PREL) 414 .Case("target1", VK_ARM_TARGET1) 415 .Case("target2", VK_ARM_TARGET2) 416 .Case("prel31", VK_ARM_PREL31) 417 .Case("sbrel", VK_ARM_SBREL) 418 .Case("tlsldo", VK_ARM_TLSLDO) 419 .Case("lo8", VK_AVR_LO8) 420 .Case("hi8", VK_AVR_HI8) 421 .Case("hlo8", VK_AVR_HLO8) 422 .Case("function", VK_WebAssembly_FUNCTION) 423 .Case("global", VK_WebAssembly_GLOBAL) 424 .Case("typeindex", VK_WebAssembly_TYPEINDEX) 425 .Case("event", VK_WebAssembly_EVENT) 426 .Case("gotpcrel32@lo", VK_AMDGPU_GOTPCREL32_LO) 427 .Case("gotpcrel32@hi", VK_AMDGPU_GOTPCREL32_HI) 428 .Case("rel32@lo", VK_AMDGPU_REL32_LO) 429 .Case("rel32@hi", VK_AMDGPU_REL32_HI) 430 .Case("rel64", VK_AMDGPU_REL64) 431 .Default(VK_Invalid); 432 } 433 434 void MCSymbolRefExpr::printVariantKind(raw_ostream &OS) const { 435 if (UseParensForSymbolVariant) 436 OS << '(' << MCSymbolRefExpr::getVariantKindName(getKind()) << ')'; 437 else 438 OS << '@' << MCSymbolRefExpr::getVariantKindName(getKind()); 439 } 440 441 /* *** */ 442 443 void MCTargetExpr::anchor() {} 444 445 /* *** */ 446 447 bool MCExpr::evaluateAsAbsolute(int64_t &Res) const { 448 return evaluateAsAbsolute(Res, nullptr, nullptr, nullptr); 449 } 450 451 bool MCExpr::evaluateAsAbsolute(int64_t &Res, 452 const MCAsmLayout &Layout) const { 453 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr); 454 } 455 456 bool MCExpr::evaluateAsAbsolute(int64_t &Res, 457 const MCAsmLayout &Layout, 458 const SectionAddrMap &Addrs) const { 459 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs); 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::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm) const { 467 return evaluateAsAbsolute(Res, Asm, nullptr, nullptr); 468 } 469 470 bool MCExpr::evaluateKnownAbsolute(int64_t &Res, 471 const MCAsmLayout &Layout) const { 472 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr, 473 true); 474 } 475 476 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, 477 const MCAsmLayout *Layout, 478 const SectionAddrMap *Addrs) const { 479 // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us 480 // absolutize differences across sections and that is what the MachO writer 481 // uses Addrs for. 482 return evaluateAsAbsolute(Res, Asm, Layout, Addrs, Addrs); 483 } 484 485 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, 486 const MCAsmLayout *Layout, 487 const SectionAddrMap *Addrs, bool InSet) const { 488 MCValue Value; 489 490 // Fast path constants. 491 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) { 492 Res = CE->getValue(); 493 return true; 494 } 495 496 bool IsRelocatable = 497 evaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs, InSet); 498 499 // Record the current value. 500 Res = Value.getConstant(); 501 502 return IsRelocatable && Value.isAbsolute(); 503 } 504 505 /// Helper method for \see EvaluateSymbolAdd(). 506 static void AttemptToFoldSymbolOffsetDifference( 507 const MCAssembler *Asm, const MCAsmLayout *Layout, 508 const SectionAddrMap *Addrs, bool InSet, const MCSymbolRefExpr *&A, 509 const MCSymbolRefExpr *&B, int64_t &Addend) { 510 if (!A || !B) 511 return; 512 513 const MCSymbol &SA = A->getSymbol(); 514 const MCSymbol &SB = B->getSymbol(); 515 516 if (SA.isUndefined() || SB.isUndefined()) 517 return; 518 519 if (!Asm->getWriter().isSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet)) 520 return; 521 522 if (SA.getFragment() == SB.getFragment() && !SA.isVariable() && 523 !SA.isUnset() && !SB.isVariable() && !SB.isUnset()) { 524 Addend += (SA.getOffset() - SB.getOffset()); 525 526 // Pointers to Thumb symbols need to have their low-bit set to allow 527 // for interworking. 528 if (Asm->isThumbFunc(&SA)) 529 Addend |= 1; 530 531 // If symbol is labeled as micromips, we set low-bit to ensure 532 // correct offset in .gcc_except_table 533 if (Asm->getBackend().isMicroMips(&SA)) 534 Addend |= 1; 535 536 // Clear the symbol expr pointers to indicate we have folded these 537 // operands. 538 A = B = nullptr; 539 return; 540 } 541 542 if (!Layout) 543 return; 544 545 const MCSection &SecA = *SA.getFragment()->getParent(); 546 const MCSection &SecB = *SB.getFragment()->getParent(); 547 548 if ((&SecA != &SecB) && !Addrs) 549 return; 550 551 // Eagerly evaluate. 552 Addend += Layout->getSymbolOffset(A->getSymbol()) - 553 Layout->getSymbolOffset(B->getSymbol()); 554 if (Addrs && (&SecA != &SecB)) 555 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB)); 556 557 // Pointers to Thumb symbols need to have their low-bit set to allow 558 // for interworking. 559 if (Asm->isThumbFunc(&SA)) 560 Addend |= 1; 561 562 // If symbol is labeled as micromips, we set low-bit to ensure 563 // correct offset in .gcc_except_table 564 if (Asm->getBackend().isMicroMips(&SA)) 565 Addend |= 1; 566 567 // Clear the symbol expr pointers to indicate we have folded these 568 // operands. 569 A = B = nullptr; 570 } 571 572 /// Evaluate the result of an add between (conceptually) two MCValues. 573 /// 574 /// This routine conceptually attempts to construct an MCValue: 575 /// Result = (Result_A - Result_B + Result_Cst) 576 /// from two MCValue's LHS and RHS where 577 /// Result = LHS + RHS 578 /// and 579 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 580 /// 581 /// This routine attempts to aggresively fold the operands such that the result 582 /// is representable in an MCValue, but may not always succeed. 583 /// 584 /// \returns True on success, false if the result is not representable in an 585 /// MCValue. 586 587 /// NOTE: It is really important to have both the Asm and Layout arguments. 588 /// They might look redundant, but this function can be used before layout 589 /// is done (see the object streamer for example) and having the Asm argument 590 /// lets us avoid relaxations early. 591 static bool 592 EvaluateSymbolicAdd(const MCAssembler *Asm, const MCAsmLayout *Layout, 593 const SectionAddrMap *Addrs, bool InSet, const MCValue &LHS, 594 const MCSymbolRefExpr *RHS_A, const MCSymbolRefExpr *RHS_B, 595 int64_t RHS_Cst, MCValue &Res) { 596 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy 597 // about dealing with modifiers. This will ultimately bite us, one day. 598 const MCSymbolRefExpr *LHS_A = LHS.getSymA(); 599 const MCSymbolRefExpr *LHS_B = LHS.getSymB(); 600 int64_t LHS_Cst = LHS.getConstant(); 601 602 // Fold the result constant immediately. 603 int64_t Result_Cst = LHS_Cst + RHS_Cst; 604 605 assert((!Layout || Asm) && 606 "Must have an assembler object if layout is given!"); 607 608 // If we have a layout, we can fold resolved differences. Do not do this if 609 // the backend requires this to be emitted as individual relocations, unless 610 // the InSet flag is set to get the current difference anyway (used for 611 // example to calculate symbol sizes). 612 if (Asm && 613 (InSet || !Asm->getBackend().requiresDiffExpressionRelocations())) { 614 // First, fold out any differences which are fully resolved. By 615 // reassociating terms in 616 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 617 // we have the four possible differences: 618 // (LHS_A - LHS_B), 619 // (LHS_A - RHS_B), 620 // (RHS_A - LHS_B), 621 // (RHS_A - RHS_B). 622 // Since we are attempting to be as aggressive as possible about folding, we 623 // attempt to evaluate each possible alternative. 624 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B, 625 Result_Cst); 626 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B, 627 Result_Cst); 628 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B, 629 Result_Cst); 630 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B, 631 Result_Cst); 632 } 633 634 // We can't represent the addition or subtraction of two symbols. 635 if ((LHS_A && RHS_A) || (LHS_B && RHS_B)) 636 return false; 637 638 // At this point, we have at most one additive symbol and one subtractive 639 // symbol -- find them. 640 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A; 641 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B; 642 643 Res = MCValue::get(A, B, Result_Cst); 644 return true; 645 } 646 647 bool MCExpr::evaluateAsRelocatable(MCValue &Res, 648 const MCAsmLayout *Layout, 649 const MCFixup *Fixup) const { 650 MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr; 651 return evaluateAsRelocatableImpl(Res, Assembler, Layout, Fixup, nullptr, 652 false); 653 } 654 655 bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const { 656 MCAssembler *Assembler = &Layout.getAssembler(); 657 return evaluateAsRelocatableImpl(Res, Assembler, &Layout, nullptr, nullptr, 658 true); 659 } 660 661 static bool canExpand(const MCSymbol &Sym, bool InSet) { 662 const MCExpr *Expr = Sym.getVariableValue(); 663 const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr); 664 if (Inner) { 665 if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF) 666 return false; 667 } 668 669 if (InSet) 670 return true; 671 return !Sym.isInSection(); 672 } 673 674 bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm, 675 const MCAsmLayout *Layout, 676 const MCFixup *Fixup, 677 const SectionAddrMap *Addrs, 678 bool InSet) const { 679 ++stats::MCExprEvaluate; 680 681 switch (getKind()) { 682 case Target: 683 return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Layout, 684 Fixup); 685 686 case Constant: 687 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue()); 688 return true; 689 690 case SymbolRef: { 691 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 692 const MCSymbol &Sym = SRE->getSymbol(); 693 694 // Evaluate recursively if this is a variable. 695 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None && 696 canExpand(Sym, InSet)) { 697 bool IsMachO = SRE->hasSubsectionsViaSymbols(); 698 if (Sym.getVariableValue()->evaluateAsRelocatableImpl( 699 Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO)) { 700 if (!IsMachO) 701 return true; 702 703 const MCSymbolRefExpr *A = Res.getSymA(); 704 const MCSymbolRefExpr *B = Res.getSymB(); 705 // FIXME: This is small hack. Given 706 // a = b + 4 707 // .long a 708 // the OS X assembler will completely drop the 4. We should probably 709 // include it in the relocation or produce an error if that is not 710 // possible. 711 // Allow constant expressions. 712 if (!A && !B) 713 return true; 714 // Allows aliases with zero offset. 715 if (Res.getConstant() == 0 && (!A || !B)) 716 return true; 717 } 718 } 719 720 Res = MCValue::get(SRE, nullptr, 0); 721 return true; 722 } 723 724 case Unary: { 725 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this); 726 MCValue Value; 727 728 if (!AUE->getSubExpr()->evaluateAsRelocatableImpl(Value, Asm, Layout, Fixup, 729 Addrs, InSet)) 730 return false; 731 732 switch (AUE->getOpcode()) { 733 case MCUnaryExpr::LNot: 734 if (!Value.isAbsolute()) 735 return false; 736 Res = MCValue::get(!Value.getConstant()); 737 break; 738 case MCUnaryExpr::Minus: 739 /// -(a - b + const) ==> (b - a - const) 740 if (Value.getSymA() && !Value.getSymB()) 741 return false; 742 743 // The cast avoids undefined behavior if the constant is INT64_MIN. 744 Res = MCValue::get(Value.getSymB(), Value.getSymA(), 745 -(uint64_t)Value.getConstant()); 746 break; 747 case MCUnaryExpr::Not: 748 if (!Value.isAbsolute()) 749 return false; 750 Res = MCValue::get(~Value.getConstant()); 751 break; 752 case MCUnaryExpr::Plus: 753 Res = Value; 754 break; 755 } 756 757 return true; 758 } 759 760 case Binary: { 761 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this); 762 MCValue LHSValue, RHSValue; 763 764 if (!ABE->getLHS()->evaluateAsRelocatableImpl(LHSValue, Asm, Layout, Fixup, 765 Addrs, InSet) || 766 !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup, 767 Addrs, InSet)) { 768 // Check if both are Target Expressions, see if we can compare them. 769 if (const MCTargetExpr *L = dyn_cast<MCTargetExpr>(ABE->getLHS())) 770 if (const MCTargetExpr *R = cast<MCTargetExpr>(ABE->getRHS())) { 771 switch (ABE->getOpcode()) { 772 case MCBinaryExpr::EQ: 773 Res = MCValue::get((L->isEqualTo(R)) ? -1 : 0); 774 return true; 775 case MCBinaryExpr::NE: 776 Res = MCValue::get((R->isEqualTo(R)) ? 0 : -1); 777 return true; 778 default: break; 779 } 780 } 781 return false; 782 } 783 784 // We only support a few operations on non-constant expressions, handle 785 // those first. 786 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) { 787 switch (ABE->getOpcode()) { 788 default: 789 return false; 790 case MCBinaryExpr::Sub: 791 // Negate RHS and add. 792 // The cast avoids undefined behavior if the constant is INT64_MIN. 793 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 794 RHSValue.getSymB(), RHSValue.getSymA(), 795 -(uint64_t)RHSValue.getConstant(), Res); 796 797 case MCBinaryExpr::Add: 798 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 799 RHSValue.getSymA(), RHSValue.getSymB(), 800 RHSValue.getConstant(), Res); 801 } 802 } 803 804 // FIXME: We need target hooks for the evaluation. It may be limited in 805 // width, and gas defines the result of comparisons differently from 806 // Apple as. 807 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant(); 808 int64_t Result = 0; 809 auto Op = ABE->getOpcode(); 810 switch (Op) { 811 case MCBinaryExpr::AShr: Result = LHS >> RHS; break; 812 case MCBinaryExpr::Add: Result = LHS + RHS; break; 813 case MCBinaryExpr::And: Result = LHS & RHS; break; 814 case MCBinaryExpr::Div: 815 case MCBinaryExpr::Mod: 816 // Handle division by zero. gas just emits a warning and keeps going, 817 // we try to be stricter. 818 // FIXME: Currently the caller of this function has no way to understand 819 // we're bailing out because of 'division by zero'. Therefore, it will 820 // emit a 'expected relocatable expression' error. It would be nice to 821 // change this code to emit a better diagnostic. 822 if (RHS == 0) 823 return false; 824 if (ABE->getOpcode() == MCBinaryExpr::Div) 825 Result = LHS / RHS; 826 else 827 Result = LHS % RHS; 828 break; 829 case MCBinaryExpr::EQ: Result = LHS == RHS; break; 830 case MCBinaryExpr::GT: Result = LHS > RHS; break; 831 case MCBinaryExpr::GTE: Result = LHS >= RHS; break; 832 case MCBinaryExpr::LAnd: Result = LHS && RHS; break; 833 case MCBinaryExpr::LOr: Result = LHS || RHS; break; 834 case MCBinaryExpr::LShr: Result = uint64_t(LHS) >> uint64_t(RHS); break; 835 case MCBinaryExpr::LT: Result = LHS < RHS; break; 836 case MCBinaryExpr::LTE: Result = LHS <= RHS; break; 837 case MCBinaryExpr::Mul: Result = LHS * RHS; break; 838 case MCBinaryExpr::NE: Result = LHS != RHS; break; 839 case MCBinaryExpr::Or: Result = LHS | RHS; break; 840 case MCBinaryExpr::Shl: Result = uint64_t(LHS) << uint64_t(RHS); break; 841 case MCBinaryExpr::Sub: Result = LHS - RHS; break; 842 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break; 843 } 844 845 switch (Op) { 846 default: 847 Res = MCValue::get(Result); 848 break; 849 case MCBinaryExpr::EQ: 850 case MCBinaryExpr::GT: 851 case MCBinaryExpr::GTE: 852 case MCBinaryExpr::LT: 853 case MCBinaryExpr::LTE: 854 case MCBinaryExpr::NE: 855 // A comparison operator returns a -1 if true and 0 if false. 856 Res = MCValue::get(Result ? -1 : 0); 857 break; 858 } 859 860 return true; 861 } 862 } 863 864 llvm_unreachable("Invalid assembly expression kind!"); 865 } 866 867 MCFragment *MCExpr::findAssociatedFragment() const { 868 switch (getKind()) { 869 case Target: 870 // We never look through target specific expressions. 871 return cast<MCTargetExpr>(this)->findAssociatedFragment(); 872 873 case Constant: 874 return MCSymbol::AbsolutePseudoFragment; 875 876 case SymbolRef: { 877 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 878 const MCSymbol &Sym = SRE->getSymbol(); 879 return Sym.getFragment(); 880 } 881 882 case Unary: 883 return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment(); 884 885 case Binary: { 886 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this); 887 MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment(); 888 MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment(); 889 890 // If either is absolute, return the other. 891 if (LHS_F == MCSymbol::AbsolutePseudoFragment) 892 return RHS_F; 893 if (RHS_F == MCSymbol::AbsolutePseudoFragment) 894 return LHS_F; 895 896 // Not always correct, but probably the best we can do without more context. 897 if (BE->getOpcode() == MCBinaryExpr::Sub) 898 return MCSymbol::AbsolutePseudoFragment; 899 900 // Otherwise, return the first non-null fragment. 901 return LHS_F ? LHS_F : RHS_F; 902 } 903 } 904 905 llvm_unreachable("Invalid assembly expression kind!"); 906 } 907