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/MC/MCAsmInfo.h" 14 #include "llvm/MC/MCAsmLayout.h" 15 #include "llvm/MC/MCAssembler.h" 16 #include "llvm/MC/MCContext.h" 17 #include "llvm/MC/MCObjectWriter.h" 18 #include "llvm/MC/MCSymbol.h" 19 #include "llvm/MC/MCValue.h" 20 #include "llvm/Support/Casting.h" 21 #include "llvm/Support/Compiler.h" 22 #include "llvm/Support/Debug.h" 23 #include "llvm/Support/ErrorHandling.h" 24 #include "llvm/Support/raw_ostream.h" 25 #include <cassert> 26 #include <cstdint> 27 28 using namespace llvm; 29 30 #define DEBUG_TYPE "mcexpr" 31 32 namespace { 33 namespace stats { 34 35 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations"); 36 37 } // end namespace stats 38 } // end anonymous namespace 39 40 void MCExpr::print(raw_ostream &OS, const MCAsmInfo *MAI, bool InParens) const { 41 switch (getKind()) { 42 case MCExpr::Target: 43 return cast<MCTargetExpr>(this)->printImpl(OS, MAI); 44 case MCExpr::Constant: 45 OS << cast<MCConstantExpr>(*this).getValue(); 46 return; 47 48 case MCExpr::SymbolRef: { 49 const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this); 50 const MCSymbol &Sym = SRE.getSymbol(); 51 // Parenthesize names that start with $ so that they don't look like 52 // absolute names. 53 bool UseParens = 54 !InParens && !Sym.getName().empty() && Sym.getName()[0] == '$'; 55 if (UseParens) { 56 OS << '('; 57 Sym.print(OS, MAI); 58 OS << ')'; 59 } else 60 Sym.print(OS, MAI); 61 62 if (SRE.getKind() != MCSymbolRefExpr::VK_None) 63 SRE.printVariantKind(OS); 64 65 return; 66 } 67 68 case MCExpr::Unary: { 69 const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this); 70 switch (UE.getOpcode()) { 71 case MCUnaryExpr::LNot: OS << '!'; break; 72 case MCUnaryExpr::Minus: OS << '-'; break; 73 case MCUnaryExpr::Not: OS << '~'; break; 74 case MCUnaryExpr::Plus: OS << '+'; break; 75 } 76 UE.getSubExpr()->print(OS, MAI); 77 return; 78 } 79 80 case MCExpr::Binary: { 81 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this); 82 83 // Only print parens around the LHS if it is non-trivial. 84 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) { 85 BE.getLHS()->print(OS, MAI); 86 } else { 87 OS << '('; 88 BE.getLHS()->print(OS, MAI); 89 OS << ')'; 90 } 91 92 switch (BE.getOpcode()) { 93 case MCBinaryExpr::Add: 94 // Print "X-42" instead of "X+-42". 95 if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) { 96 if (RHSC->getValue() < 0) { 97 OS << RHSC->getValue(); 98 return; 99 } 100 } 101 102 OS << '+'; 103 break; 104 case MCBinaryExpr::AShr: OS << ">>"; break; 105 case MCBinaryExpr::And: OS << '&'; break; 106 case MCBinaryExpr::Div: OS << '/'; break; 107 case MCBinaryExpr::EQ: OS << "=="; break; 108 case MCBinaryExpr::GT: OS << '>'; break; 109 case MCBinaryExpr::GTE: OS << ">="; break; 110 case MCBinaryExpr::LAnd: OS << "&&"; break; 111 case MCBinaryExpr::LOr: OS << "||"; break; 112 case MCBinaryExpr::LShr: OS << ">>"; break; 113 case MCBinaryExpr::LT: OS << '<'; break; 114 case MCBinaryExpr::LTE: OS << "<="; break; 115 case MCBinaryExpr::Mod: OS << '%'; break; 116 case MCBinaryExpr::Mul: OS << '*'; break; 117 case MCBinaryExpr::NE: OS << "!="; break; 118 case MCBinaryExpr::Or: OS << '|'; break; 119 case MCBinaryExpr::Shl: OS << "<<"; break; 120 case MCBinaryExpr::Sub: OS << '-'; break; 121 case MCBinaryExpr::Xor: OS << '^'; break; 122 } 123 124 // Only print parens around the LHS if it is non-trivial. 125 if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) { 126 BE.getRHS()->print(OS, MAI); 127 } else { 128 OS << '('; 129 BE.getRHS()->print(OS, MAI); 130 OS << ')'; 131 } 132 return; 133 } 134 } 135 136 llvm_unreachable("Invalid expression kind!"); 137 } 138 139 #ifdef LLVM_ENABLE_DUMP 140 LLVM_DUMP_METHOD void MCExpr::dump() const { 141 dbgs() << *this; 142 dbgs() << '\n'; 143 } 144 #endif 145 146 /* *** */ 147 148 const MCBinaryExpr *MCBinaryExpr::create(Opcode Opc, const MCExpr *LHS, 149 const MCExpr *RHS, MCContext &Ctx, 150 SMLoc Loc) { 151 return new (Ctx) MCBinaryExpr(Opc, LHS, RHS, Loc); 152 } 153 154 const MCUnaryExpr *MCUnaryExpr::create(Opcode Opc, const MCExpr *Expr, 155 MCContext &Ctx, SMLoc Loc) { 156 return new (Ctx) MCUnaryExpr(Opc, Expr, Loc); 157 } 158 159 const MCConstantExpr *MCConstantExpr::create(int64_t Value, MCContext &Ctx) { 160 return new (Ctx) MCConstantExpr(Value); 161 } 162 163 /* *** */ 164 165 MCSymbolRefExpr::MCSymbolRefExpr(const MCSymbol *Symbol, VariantKind Kind, 166 const MCAsmInfo *MAI, SMLoc Loc) 167 : MCExpr(MCExpr::SymbolRef, Loc), Kind(Kind), 168 UseParensForSymbolVariant(MAI->useParensForSymbolVariant()), 169 HasSubsectionsViaSymbols(MAI->hasSubsectionsViaSymbols()), 170 Symbol(Symbol) { 171 assert(Symbol); 172 } 173 174 const MCSymbolRefExpr *MCSymbolRefExpr::create(const MCSymbol *Sym, 175 VariantKind Kind, 176 MCContext &Ctx, SMLoc Loc) { 177 return new (Ctx) MCSymbolRefExpr(Sym, Kind, Ctx.getAsmInfo(), Loc); 178 } 179 180 const MCSymbolRefExpr *MCSymbolRefExpr::create(StringRef Name, VariantKind Kind, 181 MCContext &Ctx) { 182 return create(Ctx.getOrCreateSymbol(Name), Kind, Ctx); 183 } 184 185 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) { 186 switch (Kind) { 187 case VK_Invalid: return "<<invalid>>"; 188 case VK_None: return "<<none>>"; 189 190 case VK_DTPOFF: return "DTPOFF"; 191 case VK_DTPREL: return "DTPREL"; 192 case VK_GOT: return "GOT"; 193 case VK_GOTOFF: return "GOTOFF"; 194 case VK_GOTREL: return "GOTREL"; 195 case VK_GOTPCREL: return "GOTPCREL"; 196 case VK_GOTTPOFF: return "GOTTPOFF"; 197 case VK_INDNTPOFF: return "INDNTPOFF"; 198 case VK_NTPOFF: return "NTPOFF"; 199 case VK_GOTNTPOFF: return "GOTNTPOFF"; 200 case VK_PLT: return "PLT"; 201 case VK_TLSGD: return "TLSGD"; 202 case VK_TLSLD: return "TLSLD"; 203 case VK_TLSLDM: return "TLSLDM"; 204 case VK_TPOFF: return "TPOFF"; 205 case VK_TPREL: return "TPREL"; 206 case VK_TLSCALL: return "tlscall"; 207 case VK_TLSDESC: return "tlsdesc"; 208 case VK_TLVP: return "TLVP"; 209 case VK_TLVPPAGE: return "TLVPPAGE"; 210 case VK_TLVPPAGEOFF: return "TLVPPAGEOFF"; 211 case VK_PAGE: return "PAGE"; 212 case VK_PAGEOFF: return "PAGEOFF"; 213 case VK_GOTPAGE: return "GOTPAGE"; 214 case VK_GOTPAGEOFF: return "GOTPAGEOFF"; 215 case VK_SECREL: return "SECREL32"; 216 case VK_SIZE: return "SIZE"; 217 case VK_WEAKREF: return "WEAKREF"; 218 case VK_X86_ABS8: return "ABS8"; 219 case VK_ARM_NONE: return "none"; 220 case VK_ARM_GOT_PREL: return "GOT_PREL"; 221 case VK_ARM_TARGET1: return "target1"; 222 case VK_ARM_TARGET2: return "target2"; 223 case VK_ARM_PREL31: return "prel31"; 224 case VK_ARM_SBREL: return "sbrel"; 225 case VK_ARM_TLSLDO: return "tlsldo"; 226 case VK_ARM_TLSDESCSEQ: return "tlsdescseq"; 227 case VK_PPC_LO: return "l"; 228 case VK_PPC_HI: return "h"; 229 case VK_PPC_HA: return "ha"; 230 case VK_PPC_HIGHER: return "higher"; 231 case VK_PPC_HIGHERA: return "highera"; 232 case VK_PPC_HIGHEST: return "highest"; 233 case VK_PPC_HIGHESTA: return "highesta"; 234 case VK_PPC_GOT_LO: return "got@l"; 235 case VK_PPC_GOT_HI: return "got@h"; 236 case VK_PPC_GOT_HA: return "got@ha"; 237 case VK_PPC_TOCBASE: return "tocbase"; 238 case VK_PPC_TOC: return "toc"; 239 case VK_PPC_TOC_LO: return "toc@l"; 240 case VK_PPC_TOC_HI: return "toc@h"; 241 case VK_PPC_TOC_HA: return "toc@ha"; 242 case VK_PPC_DTPMOD: return "dtpmod"; 243 case VK_PPC_TPREL_LO: return "tprel@l"; 244 case VK_PPC_TPREL_HI: return "tprel@h"; 245 case VK_PPC_TPREL_HA: return "tprel@ha"; 246 case VK_PPC_TPREL_HIGHER: return "tprel@higher"; 247 case VK_PPC_TPREL_HIGHERA: return "tprel@highera"; 248 case VK_PPC_TPREL_HIGHEST: return "tprel@highest"; 249 case VK_PPC_TPREL_HIGHESTA: return "tprel@highesta"; 250 case VK_PPC_DTPREL_LO: return "dtprel@l"; 251 case VK_PPC_DTPREL_HI: return "dtprel@h"; 252 case VK_PPC_DTPREL_HA: return "dtprel@ha"; 253 case VK_PPC_DTPREL_HIGHER: return "dtprel@higher"; 254 case VK_PPC_DTPREL_HIGHERA: return "dtprel@highera"; 255 case VK_PPC_DTPREL_HIGHEST: return "dtprel@highest"; 256 case VK_PPC_DTPREL_HIGHESTA: return "dtprel@highesta"; 257 case VK_PPC_GOT_TPREL: return "got@tprel"; 258 case VK_PPC_GOT_TPREL_LO: return "got@tprel@l"; 259 case VK_PPC_GOT_TPREL_HI: return "got@tprel@h"; 260 case VK_PPC_GOT_TPREL_HA: return "got@tprel@ha"; 261 case VK_PPC_GOT_DTPREL: return "got@dtprel"; 262 case VK_PPC_GOT_DTPREL_LO: return "got@dtprel@l"; 263 case VK_PPC_GOT_DTPREL_HI: return "got@dtprel@h"; 264 case VK_PPC_GOT_DTPREL_HA: return "got@dtprel@ha"; 265 case VK_PPC_TLS: return "tls"; 266 case VK_PPC_GOT_TLSGD: return "got@tlsgd"; 267 case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l"; 268 case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h"; 269 case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha"; 270 case VK_PPC_TLSGD: return "tlsgd"; 271 case VK_PPC_GOT_TLSLD: return "got@tlsld"; 272 case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l"; 273 case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h"; 274 case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha"; 275 case VK_PPC_TLSLD: return "tlsld"; 276 case VK_PPC_LOCAL: return "local"; 277 case VK_COFF_IMGREL32: return "IMGREL"; 278 case VK_Hexagon_PCREL: return "PCREL"; 279 case VK_Hexagon_LO16: return "LO16"; 280 case VK_Hexagon_HI16: return "HI16"; 281 case VK_Hexagon_GPREL: return "GPREL"; 282 case VK_Hexagon_GD_GOT: return "GDGOT"; 283 case VK_Hexagon_LD_GOT: return "LDGOT"; 284 case VK_Hexagon_GD_PLT: return "GDPLT"; 285 case VK_Hexagon_LD_PLT: return "LDPLT"; 286 case VK_Hexagon_IE: return "IE"; 287 case VK_Hexagon_IE_GOT: return "IEGOT"; 288 case VK_WebAssembly_FUNCTION: return "FUNCTION"; 289 case VK_WebAssembly_TYPEINDEX: return "TYPEINDEX"; 290 case VK_AMDGPU_GOTPCREL32_LO: return "gotpcrel32@lo"; 291 case VK_AMDGPU_GOTPCREL32_HI: return "gotpcrel32@hi"; 292 case VK_AMDGPU_REL32_LO: return "rel32@lo"; 293 case VK_AMDGPU_REL32_HI: return "rel32@hi"; 294 } 295 llvm_unreachable("Invalid variant kind"); 296 } 297 298 MCSymbolRefExpr::VariantKind 299 MCSymbolRefExpr::getVariantKindForName(StringRef Name) { 300 return StringSwitch<VariantKind>(Name.lower()) 301 .Case("dtprel", VK_DTPREL) 302 .Case("dtpoff", VK_DTPOFF) 303 .Case("got", VK_GOT) 304 .Case("gotoff", VK_GOTOFF) 305 .Case("gotrel", VK_GOTREL) 306 .Case("gotpcrel", VK_GOTPCREL) 307 .Case("gottpoff", VK_GOTTPOFF) 308 .Case("indntpoff", VK_INDNTPOFF) 309 .Case("ntpoff", VK_NTPOFF) 310 .Case("gotntpoff", VK_GOTNTPOFF) 311 .Case("plt", VK_PLT) 312 .Case("tlscall", VK_TLSCALL) 313 .Case("tlsdesc", VK_TLSDESC) 314 .Case("tlsgd", VK_TLSGD) 315 .Case("tlsld", VK_TLSLD) 316 .Case("tlsldm", VK_TLSLDM) 317 .Case("tpoff", VK_TPOFF) 318 .Case("tprel", VK_TPREL) 319 .Case("tlvp", VK_TLVP) 320 .Case("tlvppage", VK_TLVPPAGE) 321 .Case("tlvppageoff", VK_TLVPPAGEOFF) 322 .Case("page", VK_PAGE) 323 .Case("pageoff", VK_PAGEOFF) 324 .Case("gotpage", VK_GOTPAGE) 325 .Case("gotpageoff", VK_GOTPAGEOFF) 326 .Case("imgrel", VK_COFF_IMGREL32) 327 .Case("secrel32", VK_SECREL) 328 .Case("size", VK_SIZE) 329 .Case("abs8", VK_X86_ABS8) 330 .Case("l", VK_PPC_LO) 331 .Case("h", VK_PPC_HI) 332 .Case("ha", VK_PPC_HA) 333 .Case("higher", VK_PPC_HIGHER) 334 .Case("highera", VK_PPC_HIGHERA) 335 .Case("highest", VK_PPC_HIGHEST) 336 .Case("highesta", VK_PPC_HIGHESTA) 337 .Case("got@l", VK_PPC_GOT_LO) 338 .Case("got@h", VK_PPC_GOT_HI) 339 .Case("got@ha", VK_PPC_GOT_HA) 340 .Case("local", VK_PPC_LOCAL) 341 .Case("tocbase", VK_PPC_TOCBASE) 342 .Case("toc", VK_PPC_TOC) 343 .Case("toc@l", VK_PPC_TOC_LO) 344 .Case("toc@h", VK_PPC_TOC_HI) 345 .Case("toc@ha", VK_PPC_TOC_HA) 346 .Case("tls", VK_PPC_TLS) 347 .Case("dtpmod", VK_PPC_DTPMOD) 348 .Case("tprel@l", VK_PPC_TPREL_LO) 349 .Case("tprel@h", VK_PPC_TPREL_HI) 350 .Case("tprel@ha", VK_PPC_TPREL_HA) 351 .Case("tprel@higher", VK_PPC_TPREL_HIGHER) 352 .Case("tprel@highera", VK_PPC_TPREL_HIGHERA) 353 .Case("tprel@highest", VK_PPC_TPREL_HIGHEST) 354 .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA) 355 .Case("dtprel@l", VK_PPC_DTPREL_LO) 356 .Case("dtprel@h", VK_PPC_DTPREL_HI) 357 .Case("dtprel@ha", VK_PPC_DTPREL_HA) 358 .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER) 359 .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA) 360 .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST) 361 .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA) 362 .Case("got@tprel", VK_PPC_GOT_TPREL) 363 .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO) 364 .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI) 365 .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA) 366 .Case("got@dtprel", VK_PPC_GOT_DTPREL) 367 .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO) 368 .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI) 369 .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA) 370 .Case("got@tlsgd", VK_PPC_GOT_TLSGD) 371 .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO) 372 .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI) 373 .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA) 374 .Case("got@tlsld", VK_PPC_GOT_TLSLD) 375 .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO) 376 .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI) 377 .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA) 378 .Case("gdgot", VK_Hexagon_GD_GOT) 379 .Case("gdplt", VK_Hexagon_GD_PLT) 380 .Case("iegot", VK_Hexagon_IE_GOT) 381 .Case("ie", VK_Hexagon_IE) 382 .Case("ldgot", VK_Hexagon_LD_GOT) 383 .Case("ldplt", VK_Hexagon_LD_PLT) 384 .Case("pcrel", VK_Hexagon_PCREL) 385 .Case("none", VK_ARM_NONE) 386 .Case("got_prel", VK_ARM_GOT_PREL) 387 .Case("target1", VK_ARM_TARGET1) 388 .Case("target2", VK_ARM_TARGET2) 389 .Case("prel31", VK_ARM_PREL31) 390 .Case("sbrel", VK_ARM_SBREL) 391 .Case("tlsldo", VK_ARM_TLSLDO) 392 .Case("gotpcrel32@lo", VK_AMDGPU_GOTPCREL32_LO) 393 .Case("gotpcrel32@hi", VK_AMDGPU_GOTPCREL32_HI) 394 .Case("rel32@lo", VK_AMDGPU_REL32_LO) 395 .Case("rel32@hi", VK_AMDGPU_REL32_HI) 396 .Default(VK_Invalid); 397 } 398 399 void MCSymbolRefExpr::printVariantKind(raw_ostream &OS) const { 400 if (UseParensForSymbolVariant) 401 OS << '(' << MCSymbolRefExpr::getVariantKindName(getKind()) << ')'; 402 else 403 OS << '@' << MCSymbolRefExpr::getVariantKindName(getKind()); 404 } 405 406 /* *** */ 407 408 void MCTargetExpr::anchor() {} 409 410 /* *** */ 411 412 bool MCExpr::evaluateAsAbsolute(int64_t &Res) const { 413 return evaluateAsAbsolute(Res, nullptr, nullptr, nullptr); 414 } 415 416 bool MCExpr::evaluateAsAbsolute(int64_t &Res, 417 const MCAsmLayout &Layout) const { 418 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr); 419 } 420 421 bool MCExpr::evaluateAsAbsolute(int64_t &Res, 422 const MCAsmLayout &Layout, 423 const SectionAddrMap &Addrs) const { 424 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs); 425 } 426 427 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const { 428 return evaluateAsAbsolute(Res, &Asm, nullptr, nullptr); 429 } 430 431 bool MCExpr::evaluateKnownAbsolute(int64_t &Res, 432 const MCAsmLayout &Layout) const { 433 return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr, 434 true); 435 } 436 437 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, 438 const MCAsmLayout *Layout, 439 const SectionAddrMap *Addrs) const { 440 // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us 441 // absolutize differences across sections and that is what the MachO writer 442 // uses Addrs for. 443 return evaluateAsAbsolute(Res, Asm, Layout, Addrs, Addrs); 444 } 445 446 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, 447 const MCAsmLayout *Layout, 448 const SectionAddrMap *Addrs, bool InSet) const { 449 MCValue Value; 450 451 // Fast path constants. 452 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) { 453 Res = CE->getValue(); 454 return true; 455 } 456 457 bool IsRelocatable = 458 evaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs, InSet); 459 460 // Record the current value. 461 Res = Value.getConstant(); 462 463 return IsRelocatable && Value.isAbsolute(); 464 } 465 466 /// \brief Helper method for \see EvaluateSymbolAdd(). 467 static void AttemptToFoldSymbolOffsetDifference( 468 const MCAssembler *Asm, const MCAsmLayout *Layout, 469 const SectionAddrMap *Addrs, bool InSet, const MCSymbolRefExpr *&A, 470 const MCSymbolRefExpr *&B, int64_t &Addend) { 471 if (!A || !B) 472 return; 473 474 const MCSymbol &SA = A->getSymbol(); 475 const MCSymbol &SB = B->getSymbol(); 476 477 if (SA.isUndefined() || SB.isUndefined()) 478 return; 479 480 if (!Asm->getWriter().isSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet)) 481 return; 482 483 if (SA.getFragment() == SB.getFragment() && !SA.isVariable() && 484 !SB.isVariable()) { 485 Addend += (SA.getOffset() - SB.getOffset()); 486 487 // Pointers to Thumb symbols need to have their low-bit set to allow 488 // for interworking. 489 if (Asm->isThumbFunc(&SA)) 490 Addend |= 1; 491 492 // Clear the symbol expr pointers to indicate we have folded these 493 // operands. 494 A = B = nullptr; 495 return; 496 } 497 498 if (!Layout) 499 return; 500 501 const MCSection &SecA = *SA.getFragment()->getParent(); 502 const MCSection &SecB = *SB.getFragment()->getParent(); 503 504 if ((&SecA != &SecB) && !Addrs) 505 return; 506 507 // Eagerly evaluate. 508 Addend += Layout->getSymbolOffset(A->getSymbol()) - 509 Layout->getSymbolOffset(B->getSymbol()); 510 if (Addrs && (&SecA != &SecB)) 511 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB)); 512 513 // Pointers to Thumb symbols need to have their low-bit set to allow 514 // for interworking. 515 if (Asm->isThumbFunc(&SA)) 516 Addend |= 1; 517 518 // Clear the symbol expr pointers to indicate we have folded these 519 // operands. 520 A = B = nullptr; 521 } 522 523 /// \brief Evaluate the result of an add between (conceptually) two MCValues. 524 /// 525 /// This routine conceptually attempts to construct an MCValue: 526 /// Result = (Result_A - Result_B + Result_Cst) 527 /// from two MCValue's LHS and RHS where 528 /// Result = LHS + RHS 529 /// and 530 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 531 /// 532 /// This routine attempts to aggresively fold the operands such that the result 533 /// is representable in an MCValue, but may not always succeed. 534 /// 535 /// \returns True on success, false if the result is not representable in an 536 /// MCValue. 537 538 /// NOTE: It is really important to have both the Asm and Layout arguments. 539 /// They might look redundant, but this function can be used before layout 540 /// is done (see the object streamer for example) and having the Asm argument 541 /// lets us avoid relaxations early. 542 static bool 543 EvaluateSymbolicAdd(const MCAssembler *Asm, const MCAsmLayout *Layout, 544 const SectionAddrMap *Addrs, bool InSet, const MCValue &LHS, 545 const MCSymbolRefExpr *RHS_A, const MCSymbolRefExpr *RHS_B, 546 int64_t RHS_Cst, MCValue &Res) { 547 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy 548 // about dealing with modifiers. This will ultimately bite us, one day. 549 const MCSymbolRefExpr *LHS_A = LHS.getSymA(); 550 const MCSymbolRefExpr *LHS_B = LHS.getSymB(); 551 int64_t LHS_Cst = LHS.getConstant(); 552 553 // Fold the result constant immediately. 554 int64_t Result_Cst = LHS_Cst + RHS_Cst; 555 556 assert((!Layout || Asm) && 557 "Must have an assembler object if layout is given!"); 558 559 // If we have a layout, we can fold resolved differences. 560 if (Asm) { 561 // First, fold out any differences which are fully resolved. By 562 // reassociating terms in 563 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 564 // we have the four possible differences: 565 // (LHS_A - LHS_B), 566 // (LHS_A - RHS_B), 567 // (RHS_A - LHS_B), 568 // (RHS_A - RHS_B). 569 // Since we are attempting to be as aggressive as possible about folding, we 570 // attempt to evaluate each possible alternative. 571 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B, 572 Result_Cst); 573 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B, 574 Result_Cst); 575 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B, 576 Result_Cst); 577 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B, 578 Result_Cst); 579 } 580 581 // We can't represent the addition or subtraction of two symbols. 582 if ((LHS_A && RHS_A) || (LHS_B && RHS_B)) 583 return false; 584 585 // At this point, we have at most one additive symbol and one subtractive 586 // symbol -- find them. 587 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A; 588 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B; 589 590 Res = MCValue::get(A, B, Result_Cst); 591 return true; 592 } 593 594 bool MCExpr::evaluateAsRelocatable(MCValue &Res, 595 const MCAsmLayout *Layout, 596 const MCFixup *Fixup) const { 597 MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr; 598 return evaluateAsRelocatableImpl(Res, Assembler, Layout, Fixup, nullptr, 599 false); 600 } 601 602 bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const { 603 MCAssembler *Assembler = &Layout.getAssembler(); 604 return evaluateAsRelocatableImpl(Res, Assembler, &Layout, nullptr, nullptr, 605 true); 606 } 607 608 static bool canExpand(const MCSymbol &Sym, bool InSet) { 609 const MCExpr *Expr = Sym.getVariableValue(); 610 const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr); 611 if (Inner) { 612 if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF) 613 return false; 614 } 615 616 if (InSet) 617 return true; 618 return !Sym.isInSection(); 619 } 620 621 bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm, 622 const MCAsmLayout *Layout, 623 const MCFixup *Fixup, 624 const SectionAddrMap *Addrs, 625 bool InSet) const { 626 ++stats::MCExprEvaluate; 627 628 switch (getKind()) { 629 case Target: 630 return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Layout, 631 Fixup); 632 633 case Constant: 634 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue()); 635 return true; 636 637 case SymbolRef: { 638 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 639 const MCSymbol &Sym = SRE->getSymbol(); 640 641 // Evaluate recursively if this is a variable. 642 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None && 643 canExpand(Sym, InSet)) { 644 bool IsMachO = SRE->hasSubsectionsViaSymbols(); 645 if (Sym.getVariableValue()->evaluateAsRelocatableImpl( 646 Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO)) { 647 if (!IsMachO) 648 return true; 649 650 const MCSymbolRefExpr *A = Res.getSymA(); 651 const MCSymbolRefExpr *B = Res.getSymB(); 652 // FIXME: This is small hack. Given 653 // a = b + 4 654 // .long a 655 // the OS X assembler will completely drop the 4. We should probably 656 // include it in the relocation or produce an error if that is not 657 // possible. 658 // Allow constant expressions. 659 if (!A && !B) 660 return true; 661 // Allows aliases with zero offset. 662 if (Res.getConstant() == 0 && (!A || !B)) 663 return true; 664 } 665 } 666 667 Res = MCValue::get(SRE, nullptr, 0); 668 return true; 669 } 670 671 case Unary: { 672 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this); 673 MCValue Value; 674 675 if (!AUE->getSubExpr()->evaluateAsRelocatableImpl(Value, Asm, Layout, Fixup, 676 Addrs, InSet)) 677 return false; 678 679 switch (AUE->getOpcode()) { 680 case MCUnaryExpr::LNot: 681 if (!Value.isAbsolute()) 682 return false; 683 Res = MCValue::get(!Value.getConstant()); 684 break; 685 case MCUnaryExpr::Minus: 686 /// -(a - b + const) ==> (b - a - const) 687 if (Value.getSymA() && !Value.getSymB()) 688 return false; 689 690 // The cast avoids undefined behavior if the constant is INT64_MIN. 691 Res = MCValue::get(Value.getSymB(), Value.getSymA(), 692 -(uint64_t)Value.getConstant()); 693 break; 694 case MCUnaryExpr::Not: 695 if (!Value.isAbsolute()) 696 return false; 697 Res = MCValue::get(~Value.getConstant()); 698 break; 699 case MCUnaryExpr::Plus: 700 Res = Value; 701 break; 702 } 703 704 return true; 705 } 706 707 case Binary: { 708 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this); 709 MCValue LHSValue, RHSValue; 710 711 if (!ABE->getLHS()->evaluateAsRelocatableImpl(LHSValue, Asm, Layout, Fixup, 712 Addrs, InSet) || 713 !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup, 714 Addrs, InSet)) 715 return false; 716 717 // We only support a few operations on non-constant expressions, handle 718 // those first. 719 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) { 720 switch (ABE->getOpcode()) { 721 default: 722 return false; 723 case MCBinaryExpr::Sub: 724 // Negate RHS and add. 725 // The cast avoids undefined behavior if the constant is INT64_MIN. 726 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 727 RHSValue.getSymB(), RHSValue.getSymA(), 728 -(uint64_t)RHSValue.getConstant(), Res); 729 730 case MCBinaryExpr::Add: 731 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 732 RHSValue.getSymA(), RHSValue.getSymB(), 733 RHSValue.getConstant(), Res); 734 } 735 } 736 737 // FIXME: We need target hooks for the evaluation. It may be limited in 738 // width, and gas defines the result of comparisons differently from 739 // Apple as. 740 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant(); 741 int64_t Result = 0; 742 switch (ABE->getOpcode()) { 743 case MCBinaryExpr::AShr: Result = LHS >> RHS; break; 744 case MCBinaryExpr::Add: Result = LHS + RHS; break; 745 case MCBinaryExpr::And: Result = LHS & RHS; break; 746 case MCBinaryExpr::Div: 747 // Handle division by zero. gas just emits a warning and keeps going, 748 // we try to be stricter. 749 // FIXME: Currently the caller of this function has no way to understand 750 // we're bailing out because of 'division by zero'. Therefore, it will 751 // emit a 'expected relocatable expression' error. It would be nice to 752 // change this code to emit a better diagnostic. 753 if (RHS == 0) 754 return false; 755 Result = LHS / RHS; 756 break; 757 case MCBinaryExpr::EQ: Result = LHS == RHS; break; 758 case MCBinaryExpr::GT: Result = LHS > RHS; break; 759 case MCBinaryExpr::GTE: Result = LHS >= RHS; break; 760 case MCBinaryExpr::LAnd: Result = LHS && RHS; break; 761 case MCBinaryExpr::LOr: Result = LHS || RHS; break; 762 case MCBinaryExpr::LShr: Result = uint64_t(LHS) >> uint64_t(RHS); break; 763 case MCBinaryExpr::LT: Result = LHS < RHS; break; 764 case MCBinaryExpr::LTE: Result = LHS <= RHS; break; 765 case MCBinaryExpr::Mod: Result = LHS % RHS; break; 766 case MCBinaryExpr::Mul: Result = LHS * RHS; break; 767 case MCBinaryExpr::NE: Result = LHS != RHS; break; 768 case MCBinaryExpr::Or: Result = LHS | RHS; break; 769 case MCBinaryExpr::Shl: Result = uint64_t(LHS) << uint64_t(RHS); break; 770 case MCBinaryExpr::Sub: Result = LHS - RHS; break; 771 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break; 772 } 773 774 Res = MCValue::get(Result); 775 return true; 776 } 777 } 778 779 llvm_unreachable("Invalid assembly expression kind!"); 780 } 781 782 MCFragment *MCExpr::findAssociatedFragment() const { 783 switch (getKind()) { 784 case Target: 785 // We never look through target specific expressions. 786 return cast<MCTargetExpr>(this)->findAssociatedFragment(); 787 788 case Constant: 789 return MCSymbol::AbsolutePseudoFragment; 790 791 case SymbolRef: { 792 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 793 const MCSymbol &Sym = SRE->getSymbol(); 794 return Sym.getFragment(); 795 } 796 797 case Unary: 798 return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment(); 799 800 case Binary: { 801 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this); 802 MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment(); 803 MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment(); 804 805 // If either is absolute, return the other. 806 if (LHS_F == MCSymbol::AbsolutePseudoFragment) 807 return RHS_F; 808 if (RHS_F == MCSymbol::AbsolutePseudoFragment) 809 return LHS_F; 810 811 // Not always correct, but probably the best we can do without more context. 812 if (BE->getOpcode() == MCBinaryExpr::Sub) 813 return MCSymbol::AbsolutePseudoFragment; 814 815 // Otherwise, return the first non-null fragment. 816 return LHS_F ? LHS_F : RHS_F; 817 } 818 } 819 820 llvm_unreachable("Invalid assembly expression kind!"); 821 } 822