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 #define DEBUG_TYPE "mcexpr" 11 #include "llvm/MC/MCExpr.h" 12 #include "llvm/ADT/Statistic.h" 13 #include "llvm/ADT/StringSwitch.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/Debug.h" 21 #include "llvm/Support/ErrorHandling.h" 22 #include "llvm/Support/raw_ostream.h" 23 using namespace llvm; 24 25 namespace { 26 namespace stats { 27 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations"); 28 } 29 } 30 31 void MCExpr::print(raw_ostream &OS) const { 32 switch (getKind()) { 33 case MCExpr::Target: 34 return cast<MCTargetExpr>(this)->PrintImpl(OS); 35 case MCExpr::Constant: 36 OS << cast<MCConstantExpr>(*this).getValue(); 37 return; 38 39 case MCExpr::SymbolRef: { 40 const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this); 41 const MCSymbol &Sym = SRE.getSymbol(); 42 // Parenthesize names that start with $ so that they don't look like 43 // absolute names. 44 bool UseParens = Sym.getName()[0] == '$'; 45 46 if (SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_HA16 || 47 SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_LO16) { 48 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind()); 49 UseParens = true; 50 } 51 52 if (UseParens) 53 OS << '(' << Sym << ')'; 54 else 55 OS << Sym; 56 57 if (SRE.getKind() == MCSymbolRefExpr::VK_ARM_NONE || 58 SRE.getKind() == MCSymbolRefExpr::VK_ARM_PLT || 59 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TLSGD || 60 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOT || 61 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTOFF || 62 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TPOFF || 63 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTTPOFF || 64 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TARGET1 || 65 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TARGET2 || 66 SRE.getKind() == MCSymbolRefExpr::VK_ARM_PREL31) 67 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind()); 68 else if (SRE.getKind() != MCSymbolRefExpr::VK_None && 69 SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_HA16 && 70 SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_LO16) 71 OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind()); 72 73 return; 74 } 75 76 case MCExpr::Unary: { 77 const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this); 78 switch (UE.getOpcode()) { 79 case MCUnaryExpr::LNot: OS << '!'; break; 80 case MCUnaryExpr::Minus: OS << '-'; break; 81 case MCUnaryExpr::Not: OS << '~'; break; 82 case MCUnaryExpr::Plus: OS << '+'; break; 83 } 84 OS << *UE.getSubExpr(); 85 return; 86 } 87 88 case MCExpr::Binary: { 89 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this); 90 91 // Only print parens around the LHS if it is non-trivial. 92 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) { 93 OS << *BE.getLHS(); 94 } else { 95 OS << '(' << *BE.getLHS() << ')'; 96 } 97 98 switch (BE.getOpcode()) { 99 case MCBinaryExpr::Add: 100 // Print "X-42" instead of "X+-42". 101 if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) { 102 if (RHSC->getValue() < 0) { 103 OS << RHSC->getValue(); 104 return; 105 } 106 } 107 108 OS << '+'; 109 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::LT: OS << '<'; break; 118 case MCBinaryExpr::LTE: OS << "<="; break; 119 case MCBinaryExpr::Mod: OS << '%'; break; 120 case MCBinaryExpr::Mul: OS << '*'; break; 121 case MCBinaryExpr::NE: OS << "!="; break; 122 case MCBinaryExpr::Or: OS << '|'; break; 123 case MCBinaryExpr::Shl: OS << "<<"; break; 124 case MCBinaryExpr::Shr: 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 OS << *BE.getRHS(); 132 } else { 133 OS << '(' << *BE.getRHS() << ')'; 134 } 135 return; 136 } 137 } 138 139 llvm_unreachable("Invalid expression kind!"); 140 } 141 142 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 143 void MCExpr::dump() const { 144 print(dbgs()); 145 dbgs() << '\n'; 146 } 147 #endif 148 149 /* *** */ 150 151 const MCBinaryExpr *MCBinaryExpr::Create(Opcode Opc, const MCExpr *LHS, 152 const MCExpr *RHS, MCContext &Ctx) { 153 return new (Ctx) MCBinaryExpr(Opc, LHS, RHS); 154 } 155 156 const MCUnaryExpr *MCUnaryExpr::Create(Opcode Opc, const MCExpr *Expr, 157 MCContext &Ctx) { 158 return new (Ctx) MCUnaryExpr(Opc, Expr); 159 } 160 161 const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) { 162 return new (Ctx) MCConstantExpr(Value); 163 } 164 165 /* *** */ 166 167 const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym, 168 VariantKind Kind, 169 MCContext &Ctx) { 170 return new (Ctx) MCSymbolRefExpr(Sym, Kind); 171 } 172 173 const MCSymbolRefExpr *MCSymbolRefExpr::Create(StringRef Name, VariantKind Kind, 174 MCContext &Ctx) { 175 return Create(Ctx.GetOrCreateSymbol(Name), Kind, Ctx); 176 } 177 178 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) { 179 switch (Kind) { 180 case VK_Invalid: return "<<invalid>>"; 181 case VK_None: return "<<none>>"; 182 183 case VK_GOT: return "GOT"; 184 case VK_GOTOFF: return "GOTOFF"; 185 case VK_GOTPCREL: return "GOTPCREL"; 186 case VK_GOTTPOFF: return "GOTTPOFF"; 187 case VK_INDNTPOFF: return "INDNTPOFF"; 188 case VK_NTPOFF: return "NTPOFF"; 189 case VK_GOTNTPOFF: return "GOTNTPOFF"; 190 case VK_PLT: return "PLT"; 191 case VK_TLSGD: return "TLSGD"; 192 case VK_TLSLD: return "TLSLD"; 193 case VK_TLSLDM: return "TLSLDM"; 194 case VK_TPOFF: return "TPOFF"; 195 case VK_DTPOFF: return "DTPOFF"; 196 case VK_TLVP: return "TLVP"; 197 case VK_SECREL: return "SECREL"; 198 case VK_ARM_NONE: return "(NONE)"; 199 case VK_ARM_PLT: return "(PLT)"; 200 case VK_ARM_GOT: return "(GOT)"; 201 case VK_ARM_GOTOFF: return "(GOTOFF)"; 202 case VK_ARM_TPOFF: return "(tpoff)"; 203 case VK_ARM_GOTTPOFF: return "(gottpoff)"; 204 case VK_ARM_TLSGD: return "(tlsgd)"; 205 case VK_ARM_TARGET1: return "(target1)"; 206 case VK_ARM_TARGET2: return "(target2)"; 207 case VK_ARM_PREL31: return "(prel31)"; 208 case VK_PPC_TOC: return "tocbase"; 209 case VK_PPC_TOC_ENTRY: return "toc"; 210 case VK_PPC_DARWIN_HA16: return "ha16"; 211 case VK_PPC_DARWIN_LO16: return "lo16"; 212 case VK_PPC_GAS_HA16: return "ha"; 213 case VK_PPC_GAS_LO16: return "l"; 214 case VK_PPC_TPREL16_HA: return "tprel@ha"; 215 case VK_PPC_TPREL16_LO: return "tprel@l"; 216 case VK_PPC_DTPREL16_HA: return "dtprel@ha"; 217 case VK_PPC_DTPREL16_LO: return "dtprel@l"; 218 case VK_PPC_TOC16_HA: return "toc@ha"; 219 case VK_PPC_TOC16_LO: return "toc@l"; 220 case VK_PPC_GOT_TPREL16_HA: return "got@tprel@ha"; 221 case VK_PPC_GOT_TPREL16_LO: return "got@tprel@l"; 222 case VK_PPC_TLS: return "tls"; 223 case VK_PPC_GOT_TLSGD16_HA: return "got@tlsgd@ha"; 224 case VK_PPC_GOT_TLSGD16_LO: return "got@tlsgd@l"; 225 case VK_PPC_GOT_TLSLD16_HA: return "got@tlsld@ha"; 226 case VK_PPC_GOT_TLSLD16_LO: return "got@tlsld@l"; 227 case VK_PPC_TLSGD: return "tlsgd"; 228 case VK_PPC_TLSLD: return "tlsld"; 229 case VK_Mips_GPREL: return "GPREL"; 230 case VK_Mips_GOT_CALL: return "GOT_CALL"; 231 case VK_Mips_GOT16: return "GOT16"; 232 case VK_Mips_GOT: return "GOT"; 233 case VK_Mips_ABS_HI: return "ABS_HI"; 234 case VK_Mips_ABS_LO: return "ABS_LO"; 235 case VK_Mips_TLSGD: return "TLSGD"; 236 case VK_Mips_TLSLDM: return "TLSLDM"; 237 case VK_Mips_DTPREL_HI: return "DTPREL_HI"; 238 case VK_Mips_DTPREL_LO: return "DTPREL_LO"; 239 case VK_Mips_GOTTPREL: return "GOTTPREL"; 240 case VK_Mips_TPREL_HI: return "TPREL_HI"; 241 case VK_Mips_TPREL_LO: return "TPREL_LO"; 242 case VK_Mips_GPOFF_HI: return "GPOFF_HI"; 243 case VK_Mips_GPOFF_LO: return "GPOFF_LO"; 244 case VK_Mips_GOT_DISP: return "GOT_DISP"; 245 case VK_Mips_GOT_PAGE: return "GOT_PAGE"; 246 case VK_Mips_GOT_OFST: return "GOT_OFST"; 247 case VK_Mips_HIGHER: return "HIGHER"; 248 case VK_Mips_HIGHEST: return "HIGHEST"; 249 case VK_Mips_GOT_HI16: return "GOT_HI16"; 250 case VK_Mips_GOT_LO16: return "GOT_LO16"; 251 case VK_Mips_CALL_HI16: return "CALL_HI16"; 252 case VK_Mips_CALL_LO16: return "CALL_LO16"; 253 } 254 llvm_unreachable("Invalid variant kind"); 255 } 256 257 MCSymbolRefExpr::VariantKind 258 MCSymbolRefExpr::getVariantKindForName(StringRef Name) { 259 return StringSwitch<VariantKind>(Name) 260 .Case("GOT", VK_GOT) 261 .Case("got", VK_GOT) 262 .Case("GOTOFF", VK_GOTOFF) 263 .Case("gotoff", VK_GOTOFF) 264 .Case("GOTPCREL", VK_GOTPCREL) 265 .Case("gotpcrel", VK_GOTPCREL) 266 .Case("GOTTPOFF", VK_GOTTPOFF) 267 .Case("gottpoff", VK_GOTTPOFF) 268 .Case("INDNTPOFF", VK_INDNTPOFF) 269 .Case("indntpoff", VK_INDNTPOFF) 270 .Case("NTPOFF", VK_NTPOFF) 271 .Case("ntpoff", VK_NTPOFF) 272 .Case("GOTNTPOFF", VK_GOTNTPOFF) 273 .Case("gotntpoff", VK_GOTNTPOFF) 274 .Case("PLT", VK_PLT) 275 .Case("plt", VK_PLT) 276 .Case("TLSGD", VK_TLSGD) 277 .Case("tlsgd", VK_TLSGD) 278 .Case("TLSLD", VK_TLSLD) 279 .Case("tlsld", VK_TLSLD) 280 .Case("TLSLDM", VK_TLSLDM) 281 .Case("tlsldm", VK_TLSLDM) 282 .Case("TPOFF", VK_TPOFF) 283 .Case("tpoff", VK_TPOFF) 284 .Case("DTPOFF", VK_DTPOFF) 285 .Case("dtpoff", VK_DTPOFF) 286 .Case("TLVP", VK_TLVP) 287 .Case("tlvp", VK_TLVP) 288 .Default(VK_Invalid); 289 } 290 291 /* *** */ 292 293 void MCTargetExpr::anchor() {} 294 295 /* *** */ 296 297 bool MCExpr::EvaluateAsAbsolute(int64_t &Res) const { 298 return EvaluateAsAbsolute(Res, 0, 0, 0); 299 } 300 301 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, 302 const MCAsmLayout &Layout) const { 303 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, 0); 304 } 305 306 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, 307 const MCAsmLayout &Layout, 308 const SectionAddrMap &Addrs) const { 309 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs); 310 } 311 312 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const { 313 return EvaluateAsAbsolute(Res, &Asm, 0, 0); 314 } 315 316 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, 317 const MCAsmLayout *Layout, 318 const SectionAddrMap *Addrs) const { 319 MCValue Value; 320 321 // Fast path constants. 322 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) { 323 Res = CE->getValue(); 324 return true; 325 } 326 327 // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us 328 // absolutize differences across sections and that is what the MachO writer 329 // uses Addrs for. 330 bool IsRelocatable = 331 EvaluateAsRelocatableImpl(Value, Asm, Layout, Addrs, /*InSet*/ Addrs); 332 333 // Record the current value. 334 Res = Value.getConstant(); 335 336 return IsRelocatable && Value.isAbsolute(); 337 } 338 339 /// \brief Helper method for \see EvaluateSymbolAdd(). 340 static void AttemptToFoldSymbolOffsetDifference(const MCAssembler *Asm, 341 const MCAsmLayout *Layout, 342 const SectionAddrMap *Addrs, 343 bool InSet, 344 const MCSymbolRefExpr *&A, 345 const MCSymbolRefExpr *&B, 346 int64_t &Addend) { 347 if (!A || !B) 348 return; 349 350 const MCSymbol &SA = A->getSymbol(); 351 const MCSymbol &SB = B->getSymbol(); 352 353 if (SA.isUndefined() || SB.isUndefined()) 354 return; 355 356 if (!Asm->getWriter().IsSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet)) 357 return; 358 359 MCSymbolData &AD = Asm->getSymbolData(SA); 360 MCSymbolData &BD = Asm->getSymbolData(SB); 361 362 if (AD.getFragment() == BD.getFragment()) { 363 Addend += (AD.getOffset() - BD.getOffset()); 364 365 // Pointers to Thumb symbols need to have their low-bit set to allow 366 // for interworking. 367 if (Asm->isThumbFunc(&SA)) 368 Addend |= 1; 369 370 // Clear the symbol expr pointers to indicate we have folded these 371 // operands. 372 A = B = 0; 373 return; 374 } 375 376 if (!Layout) 377 return; 378 379 const MCSectionData &SecA = *AD.getFragment()->getParent(); 380 const MCSectionData &SecB = *BD.getFragment()->getParent(); 381 382 if ((&SecA != &SecB) && !Addrs) 383 return; 384 385 // Eagerly evaluate. 386 Addend += (Layout->getSymbolOffset(&Asm->getSymbolData(A->getSymbol())) - 387 Layout->getSymbolOffset(&Asm->getSymbolData(B->getSymbol()))); 388 if (Addrs && (&SecA != &SecB)) 389 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB)); 390 391 // Pointers to Thumb symbols need to have their low-bit set to allow 392 // for interworking. 393 if (Asm->isThumbFunc(&SA)) 394 Addend |= 1; 395 396 // Clear the symbol expr pointers to indicate we have folded these 397 // operands. 398 A = B = 0; 399 } 400 401 /// \brief Evaluate the result of an add between (conceptually) two MCValues. 402 /// 403 /// This routine conceptually attempts to construct an MCValue: 404 /// Result = (Result_A - Result_B + Result_Cst) 405 /// from two MCValue's LHS and RHS where 406 /// Result = LHS + RHS 407 /// and 408 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 409 /// 410 /// This routine attempts to aggresively fold the operands such that the result 411 /// is representable in an MCValue, but may not always succeed. 412 /// 413 /// \returns True on success, false if the result is not representable in an 414 /// MCValue. 415 416 /// NOTE: It is really important to have both the Asm and Layout arguments. 417 /// They might look redundant, but this function can be used before layout 418 /// is done (see the object streamer for example) and having the Asm argument 419 /// lets us avoid relaxations early. 420 static bool EvaluateSymbolicAdd(const MCAssembler *Asm, 421 const MCAsmLayout *Layout, 422 const SectionAddrMap *Addrs, 423 bool InSet, 424 const MCValue &LHS,const MCSymbolRefExpr *RHS_A, 425 const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst, 426 MCValue &Res) { 427 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy 428 // about dealing with modifiers. This will ultimately bite us, one day. 429 const MCSymbolRefExpr *LHS_A = LHS.getSymA(); 430 const MCSymbolRefExpr *LHS_B = LHS.getSymB(); 431 int64_t LHS_Cst = LHS.getConstant(); 432 433 // Fold the result constant immediately. 434 int64_t Result_Cst = LHS_Cst + RHS_Cst; 435 436 assert((!Layout || Asm) && 437 "Must have an assembler object if layout is given!"); 438 439 // If we have a layout, we can fold resolved differences. 440 if (Asm) { 441 // First, fold out any differences which are fully resolved. By 442 // reassociating terms in 443 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 444 // we have the four possible differences: 445 // (LHS_A - LHS_B), 446 // (LHS_A - RHS_B), 447 // (RHS_A - LHS_B), 448 // (RHS_A - RHS_B). 449 // Since we are attempting to be as aggressive as possible about folding, we 450 // attempt to evaluate each possible alternative. 451 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B, 452 Result_Cst); 453 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B, 454 Result_Cst); 455 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B, 456 Result_Cst); 457 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B, 458 Result_Cst); 459 } 460 461 // We can't represent the addition or subtraction of two symbols. 462 if ((LHS_A && RHS_A) || (LHS_B && RHS_B)) 463 return false; 464 465 // At this point, we have at most one additive symbol and one subtractive 466 // symbol -- find them. 467 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A; 468 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B; 469 470 // If we have a negated symbol, then we must have also have a non-negated 471 // symbol in order to encode the expression. 472 if (B && !A) 473 return false; 474 475 Res = MCValue::get(A, B, Result_Cst); 476 return true; 477 } 478 479 bool MCExpr::EvaluateAsRelocatable(MCValue &Res, 480 const MCAsmLayout &Layout) const { 481 return EvaluateAsRelocatableImpl(Res, &Layout.getAssembler(), &Layout, 482 0, false); 483 } 484 485 bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res, 486 const MCAssembler *Asm, 487 const MCAsmLayout *Layout, 488 const SectionAddrMap *Addrs, 489 bool InSet) const { 490 ++stats::MCExprEvaluate; 491 492 switch (getKind()) { 493 case Target: 494 return cast<MCTargetExpr>(this)->EvaluateAsRelocatableImpl(Res, Layout); 495 496 case Constant: 497 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue()); 498 return true; 499 500 case SymbolRef: { 501 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 502 const MCSymbol &Sym = SRE->getSymbol(); 503 504 // Evaluate recursively if this is a variable. 505 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) { 506 bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Asm, 507 Layout, 508 Addrs, 509 true); 510 // If we failed to simplify this to a constant, let the target 511 // handle it. 512 if (Ret && !Res.getSymA() && !Res.getSymB()) 513 return true; 514 } 515 516 Res = MCValue::get(SRE, 0, 0); 517 return true; 518 } 519 520 case Unary: { 521 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this); 522 MCValue Value; 523 524 if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Asm, Layout, 525 Addrs, InSet)) 526 return false; 527 528 switch (AUE->getOpcode()) { 529 case MCUnaryExpr::LNot: 530 if (!Value.isAbsolute()) 531 return false; 532 Res = MCValue::get(!Value.getConstant()); 533 break; 534 case MCUnaryExpr::Minus: 535 /// -(a - b + const) ==> (b - a - const) 536 if (Value.getSymA() && !Value.getSymB()) 537 return false; 538 Res = MCValue::get(Value.getSymB(), Value.getSymA(), 539 -Value.getConstant()); 540 break; 541 case MCUnaryExpr::Not: 542 if (!Value.isAbsolute()) 543 return false; 544 Res = MCValue::get(~Value.getConstant()); 545 break; 546 case MCUnaryExpr::Plus: 547 Res = Value; 548 break; 549 } 550 551 return true; 552 } 553 554 case Binary: { 555 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this); 556 MCValue LHSValue, RHSValue; 557 558 if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Asm, Layout, 559 Addrs, InSet) || 560 !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Asm, Layout, 561 Addrs, InSet)) 562 return false; 563 564 // We only support a few operations on non-constant expressions, handle 565 // those first. 566 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) { 567 switch (ABE->getOpcode()) { 568 default: 569 return false; 570 case MCBinaryExpr::Sub: 571 // Negate RHS and add. 572 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 573 RHSValue.getSymB(), RHSValue.getSymA(), 574 -RHSValue.getConstant(), 575 Res); 576 577 case MCBinaryExpr::Add: 578 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 579 RHSValue.getSymA(), RHSValue.getSymB(), 580 RHSValue.getConstant(), 581 Res); 582 } 583 } 584 585 // FIXME: We need target hooks for the evaluation. It may be limited in 586 // width, and gas defines the result of comparisons and right shifts 587 // differently from Apple as. 588 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant(); 589 int64_t Result = 0; 590 switch (ABE->getOpcode()) { 591 case MCBinaryExpr::Add: Result = LHS + RHS; break; 592 case MCBinaryExpr::And: Result = LHS & RHS; break; 593 case MCBinaryExpr::Div: Result = LHS / RHS; break; 594 case MCBinaryExpr::EQ: Result = LHS == RHS; break; 595 case MCBinaryExpr::GT: Result = LHS > RHS; break; 596 case MCBinaryExpr::GTE: Result = LHS >= RHS; break; 597 case MCBinaryExpr::LAnd: Result = LHS && RHS; break; 598 case MCBinaryExpr::LOr: Result = LHS || RHS; break; 599 case MCBinaryExpr::LT: Result = LHS < RHS; break; 600 case MCBinaryExpr::LTE: Result = LHS <= RHS; break; 601 case MCBinaryExpr::Mod: Result = LHS % RHS; break; 602 case MCBinaryExpr::Mul: Result = LHS * RHS; break; 603 case MCBinaryExpr::NE: Result = LHS != RHS; break; 604 case MCBinaryExpr::Or: Result = LHS | RHS; break; 605 case MCBinaryExpr::Shl: Result = LHS << RHS; break; 606 case MCBinaryExpr::Shr: Result = LHS >> RHS; break; 607 case MCBinaryExpr::Sub: Result = LHS - RHS; break; 608 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break; 609 } 610 611 Res = MCValue::get(Result); 612 return true; 613 } 614 } 615 616 llvm_unreachable("Invalid assembly expression kind!"); 617 } 618 619 const MCSection *MCExpr::FindAssociatedSection() const { 620 switch (getKind()) { 621 case Target: 622 // We never look through target specific expressions. 623 return cast<MCTargetExpr>(this)->FindAssociatedSection(); 624 625 case Constant: 626 return MCSymbol::AbsolutePseudoSection; 627 628 case SymbolRef: { 629 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 630 const MCSymbol &Sym = SRE->getSymbol(); 631 632 if (Sym.isDefined()) 633 return &Sym.getSection(); 634 635 return 0; 636 } 637 638 case Unary: 639 return cast<MCUnaryExpr>(this)->getSubExpr()->FindAssociatedSection(); 640 641 case Binary: { 642 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this); 643 const MCSection *LHS_S = BE->getLHS()->FindAssociatedSection(); 644 const MCSection *RHS_S = BE->getRHS()->FindAssociatedSection(); 645 646 // If either section is absolute, return the other. 647 if (LHS_S == MCSymbol::AbsolutePseudoSection) 648 return RHS_S; 649 if (RHS_S == MCSymbol::AbsolutePseudoSection) 650 return LHS_S; 651 652 // Otherwise, return the first non-null section. 653 return LHS_S ? LHS_S : RHS_S; 654 } 655 } 656 657 llvm_unreachable("Invalid assembly expression kind!"); 658 } 659
