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 if (UseParens) 46 OS << '(' << Sym << ')'; 47 else 48 OS << Sym; 49 50 if (SRE.getKind() == MCSymbolRefExpr::VK_ARM_NONE || 51 SRE.getKind() == MCSymbolRefExpr::VK_ARM_PLT || 52 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TLSGD || 53 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOT || 54 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTOFF || 55 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TPOFF || 56 SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTTPOFF || 57 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TARGET1 || 58 SRE.getKind() == MCSymbolRefExpr::VK_ARM_TARGET2 || 59 SRE.getKind() == MCSymbolRefExpr::VK_ARM_PREL31) 60 OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind()); 61 else if (SRE.getKind() != MCSymbolRefExpr::VK_None) 62 OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind()); 63 64 return; 65 } 66 67 case MCExpr::Unary: { 68 const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this); 69 switch (UE.getOpcode()) { 70 case MCUnaryExpr::LNot: OS << '!'; break; 71 case MCUnaryExpr::Minus: OS << '-'; break; 72 case MCUnaryExpr::Not: OS << '~'; break; 73 case MCUnaryExpr::Plus: OS << '+'; break; 74 } 75 OS << *UE.getSubExpr(); 76 return; 77 } 78 79 case MCExpr::Binary: { 80 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this); 81 82 // Only print parens around the LHS if it is non-trivial. 83 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) { 84 OS << *BE.getLHS(); 85 } else { 86 OS << '(' << *BE.getLHS() << ')'; 87 } 88 89 switch (BE.getOpcode()) { 90 case MCBinaryExpr::Add: 91 // Print "X-42" instead of "X+-42". 92 if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) { 93 if (RHSC->getValue() < 0) { 94 OS << RHSC->getValue(); 95 return; 96 } 97 } 98 99 OS << '+'; 100 break; 101 case MCBinaryExpr::And: OS << '&'; break; 102 case MCBinaryExpr::Div: OS << '/'; break; 103 case MCBinaryExpr::EQ: OS << "=="; break; 104 case MCBinaryExpr::GT: OS << '>'; break; 105 case MCBinaryExpr::GTE: OS << ">="; break; 106 case MCBinaryExpr::LAnd: OS << "&&"; break; 107 case MCBinaryExpr::LOr: OS << "||"; break; 108 case MCBinaryExpr::LT: OS << '<'; break; 109 case MCBinaryExpr::LTE: OS << "<="; break; 110 case MCBinaryExpr::Mod: OS << '%'; break; 111 case MCBinaryExpr::Mul: OS << '*'; break; 112 case MCBinaryExpr::NE: OS << "!="; break; 113 case MCBinaryExpr::Or: OS << '|'; break; 114 case MCBinaryExpr::Shl: OS << "<<"; break; 115 case MCBinaryExpr::Shr: OS << ">>"; break; 116 case MCBinaryExpr::Sub: OS << '-'; break; 117 case MCBinaryExpr::Xor: OS << '^'; break; 118 } 119 120 // Only print parens around the LHS if it is non-trivial. 121 if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) { 122 OS << *BE.getRHS(); 123 } else { 124 OS << '(' << *BE.getRHS() << ')'; 125 } 126 return; 127 } 128 } 129 130 llvm_unreachable("Invalid expression kind!"); 131 } 132 133 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 134 void MCExpr::dump() const { 135 print(dbgs()); 136 dbgs() << '\n'; 137 } 138 #endif 139 140 /* *** */ 141 142 const MCBinaryExpr *MCBinaryExpr::Create(Opcode Opc, const MCExpr *LHS, 143 const MCExpr *RHS, MCContext &Ctx) { 144 return new (Ctx) MCBinaryExpr(Opc, LHS, RHS); 145 } 146 147 const MCUnaryExpr *MCUnaryExpr::Create(Opcode Opc, const MCExpr *Expr, 148 MCContext &Ctx) { 149 return new (Ctx) MCUnaryExpr(Opc, Expr); 150 } 151 152 const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) { 153 return new (Ctx) MCConstantExpr(Value); 154 } 155 156 /* *** */ 157 158 const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym, 159 VariantKind Kind, 160 MCContext &Ctx) { 161 return new (Ctx) MCSymbolRefExpr(Sym, Kind); 162 } 163 164 const MCSymbolRefExpr *MCSymbolRefExpr::Create(StringRef Name, VariantKind Kind, 165 MCContext &Ctx) { 166 return Create(Ctx.GetOrCreateSymbol(Name), Kind, Ctx); 167 } 168 169 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) { 170 switch (Kind) { 171 case VK_Invalid: return "<<invalid>>"; 172 case VK_None: return "<<none>>"; 173 174 case VK_GOT: return "GOT"; 175 case VK_GOTOFF: return "GOTOFF"; 176 case VK_GOTPCREL: return "GOTPCREL"; 177 case VK_GOTTPOFF: return "GOTTPOFF"; 178 case VK_INDNTPOFF: return "INDNTPOFF"; 179 case VK_NTPOFF: return "NTPOFF"; 180 case VK_GOTNTPOFF: return "GOTNTPOFF"; 181 case VK_PLT: return "PLT"; 182 case VK_TLSGD: return "TLSGD"; 183 case VK_TLSLD: return "TLSLD"; 184 case VK_TLSLDM: return "TLSLDM"; 185 case VK_TPOFF: return "TPOFF"; 186 case VK_DTPOFF: return "DTPOFF"; 187 case VK_TLVP: return "TLVP"; 188 case VK_SECREL: return "SECREL32"; 189 case VK_ARM_NONE: return "(NONE)"; 190 case VK_ARM_PLT: return "(PLT)"; 191 case VK_ARM_GOT: return "(GOT)"; 192 case VK_ARM_GOTOFF: return "(GOTOFF)"; 193 case VK_ARM_TPOFF: return "(tpoff)"; 194 case VK_ARM_GOTTPOFF: return "(gottpoff)"; 195 case VK_ARM_TLSGD: return "(tlsgd)"; 196 case VK_ARM_TARGET1: return "(target1)"; 197 case VK_ARM_TARGET2: return "(target2)"; 198 case VK_ARM_PREL31: return "(prel31)"; 199 case VK_PPC_LO: return "l"; 200 case VK_PPC_HI: return "h"; 201 case VK_PPC_HA: return "ha"; 202 case VK_PPC_HIGHER: return "higher"; 203 case VK_PPC_HIGHERA: return "highera"; 204 case VK_PPC_HIGHEST: return "highest"; 205 case VK_PPC_HIGHESTA: return "highesta"; 206 case VK_PPC_GOT_LO: return "got@l"; 207 case VK_PPC_GOT_HI: return "got@h"; 208 case VK_PPC_GOT_HA: return "got@ha"; 209 case VK_PPC_TOCBASE: return "tocbase"; 210 case VK_PPC_TOC: return "toc"; 211 case VK_PPC_TOC_LO: return "toc@l"; 212 case VK_PPC_TOC_HI: return "toc@h"; 213 case VK_PPC_TOC_HA: return "toc@ha"; 214 case VK_PPC_DTPMOD: return "dtpmod"; 215 case VK_PPC_TPREL: return "tprel"; 216 case VK_PPC_TPREL_LO: return "tprel@l"; 217 case VK_PPC_TPREL_HI: return "tprel@h"; 218 case VK_PPC_TPREL_HA: return "tprel@ha"; 219 case VK_PPC_TPREL_HIGHER: return "tprel@higher"; 220 case VK_PPC_TPREL_HIGHERA: return "tprel@highera"; 221 case VK_PPC_TPREL_HIGHEST: return "tprel@highest"; 222 case VK_PPC_TPREL_HIGHESTA: return "tprel@highesta"; 223 case VK_PPC_DTPREL: return "dtprel"; 224 case VK_PPC_DTPREL_LO: return "dtprel@l"; 225 case VK_PPC_DTPREL_HI: return "dtprel@h"; 226 case VK_PPC_DTPREL_HA: return "dtprel@ha"; 227 case VK_PPC_DTPREL_HIGHER: return "dtprel@higher"; 228 case VK_PPC_DTPREL_HIGHERA: return "dtprel@highera"; 229 case VK_PPC_DTPREL_HIGHEST: return "dtprel@highest"; 230 case VK_PPC_DTPREL_HIGHESTA: return "dtprel@highesta"; 231 case VK_PPC_GOT_TPREL: return "got@tprel"; 232 case VK_PPC_GOT_TPREL_LO: return "got@tprel@l"; 233 case VK_PPC_GOT_TPREL_HI: return "got@tprel@h"; 234 case VK_PPC_GOT_TPREL_HA: return "got@tprel@ha"; 235 case VK_PPC_GOT_DTPREL: return "got@dtprel"; 236 case VK_PPC_GOT_DTPREL_LO: return "got@dtprel@l"; 237 case VK_PPC_GOT_DTPREL_HI: return "got@dtprel@h"; 238 case VK_PPC_GOT_DTPREL_HA: return "got@dtprel@ha"; 239 case VK_PPC_TLS: return "tls"; 240 case VK_PPC_GOT_TLSGD: return "got@tlsgd"; 241 case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l"; 242 case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h"; 243 case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha"; 244 case VK_PPC_TLSGD: return "tlsgd"; 245 case VK_PPC_GOT_TLSLD: return "got@tlsld"; 246 case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l"; 247 case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h"; 248 case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha"; 249 case VK_PPC_TLSLD: return "tlsld"; 250 case VK_Mips_GPREL: return "GPREL"; 251 case VK_Mips_GOT_CALL: return "GOT_CALL"; 252 case VK_Mips_GOT16: return "GOT16"; 253 case VK_Mips_GOT: return "GOT"; 254 case VK_Mips_ABS_HI: return "ABS_HI"; 255 case VK_Mips_ABS_LO: return "ABS_LO"; 256 case VK_Mips_TLSGD: return "TLSGD"; 257 case VK_Mips_TLSLDM: return "TLSLDM"; 258 case VK_Mips_DTPREL_HI: return "DTPREL_HI"; 259 case VK_Mips_DTPREL_LO: return "DTPREL_LO"; 260 case VK_Mips_GOTTPREL: return "GOTTPREL"; 261 case VK_Mips_TPREL_HI: return "TPREL_HI"; 262 case VK_Mips_TPREL_LO: return "TPREL_LO"; 263 case VK_Mips_GPOFF_HI: return "GPOFF_HI"; 264 case VK_Mips_GPOFF_LO: return "GPOFF_LO"; 265 case VK_Mips_GOT_DISP: return "GOT_DISP"; 266 case VK_Mips_GOT_PAGE: return "GOT_PAGE"; 267 case VK_Mips_GOT_OFST: return "GOT_OFST"; 268 case VK_Mips_HIGHER: return "HIGHER"; 269 case VK_Mips_HIGHEST: return "HIGHEST"; 270 case VK_Mips_GOT_HI16: return "GOT_HI16"; 271 case VK_Mips_GOT_LO16: return "GOT_LO16"; 272 case VK_Mips_CALL_HI16: return "CALL_HI16"; 273 case VK_Mips_CALL_LO16: return "CALL_LO16"; 274 case VK_COFF_IMGREL32: return "IMGREL32"; 275 } 276 llvm_unreachable("Invalid variant kind"); 277 } 278 279 MCSymbolRefExpr::VariantKind 280 MCSymbolRefExpr::getVariantKindForName(StringRef Name) { 281 return StringSwitch<VariantKind>(Name) 282 .Case("GOT", VK_GOT) 283 .Case("got", VK_GOT) 284 .Case("GOTOFF", VK_GOTOFF) 285 .Case("gotoff", VK_GOTOFF) 286 .Case("GOTPCREL", VK_GOTPCREL) 287 .Case("gotpcrel", VK_GOTPCREL) 288 .Case("GOTTPOFF", VK_GOTTPOFF) 289 .Case("gottpoff", VK_GOTTPOFF) 290 .Case("INDNTPOFF", VK_INDNTPOFF) 291 .Case("indntpoff", VK_INDNTPOFF) 292 .Case("NTPOFF", VK_NTPOFF) 293 .Case("ntpoff", VK_NTPOFF) 294 .Case("GOTNTPOFF", VK_GOTNTPOFF) 295 .Case("gotntpoff", VK_GOTNTPOFF) 296 .Case("PLT", VK_PLT) 297 .Case("plt", VK_PLT) 298 .Case("TLSGD", VK_TLSGD) 299 .Case("tlsgd", VK_TLSGD) 300 .Case("TLSLD", VK_TLSLD) 301 .Case("tlsld", VK_TLSLD) 302 .Case("TLSLDM", VK_TLSLDM) 303 .Case("tlsldm", VK_TLSLDM) 304 .Case("TPOFF", VK_TPOFF) 305 .Case("tpoff", VK_TPOFF) 306 .Case("DTPOFF", VK_DTPOFF) 307 .Case("dtpoff", VK_DTPOFF) 308 .Case("TLVP", VK_TLVP) 309 .Case("tlvp", VK_TLVP) 310 .Case("IMGREL", VK_COFF_IMGREL32) 311 .Case("imgrel", VK_COFF_IMGREL32) 312 .Case("SECREL32", VK_SECREL) 313 .Case("secrel32", VK_SECREL) 314 .Case("L", VK_PPC_LO) 315 .Case("l", VK_PPC_LO) 316 .Case("H", VK_PPC_HI) 317 .Case("h", VK_PPC_HI) 318 .Case("HA", VK_PPC_HA) 319 .Case("ha", VK_PPC_HA) 320 .Case("HIGHER", VK_PPC_HIGHER) 321 .Case("higher", VK_PPC_HIGHER) 322 .Case("HIGHERA", VK_PPC_HIGHERA) 323 .Case("highera", VK_PPC_HIGHERA) 324 .Case("HIGHEST", VK_PPC_HIGHEST) 325 .Case("highest", VK_PPC_HIGHEST) 326 .Case("HIGHESTA", VK_PPC_HIGHESTA) 327 .Case("highesta", VK_PPC_HIGHESTA) 328 .Case("GOT@L", VK_PPC_GOT_LO) 329 .Case("got@l", VK_PPC_GOT_LO) 330 .Case("GOT@H", VK_PPC_GOT_HI) 331 .Case("got@h", VK_PPC_GOT_HI) 332 .Case("GOT@HA", VK_PPC_GOT_HA) 333 .Case("got@ha", VK_PPC_GOT_HA) 334 .Case("TOCBASE", VK_PPC_TOCBASE) 335 .Case("tocbase", VK_PPC_TOCBASE) 336 .Case("TOC", VK_PPC_TOC) 337 .Case("toc", VK_PPC_TOC) 338 .Case("TOC@L", VK_PPC_TOC_LO) 339 .Case("toc@l", VK_PPC_TOC_LO) 340 .Case("TOC@H", VK_PPC_TOC_HI) 341 .Case("toc@h", VK_PPC_TOC_HI) 342 .Case("TOC@HA", VK_PPC_TOC_HA) 343 .Case("toc@ha", VK_PPC_TOC_HA) 344 .Case("TLS", VK_PPC_TLS) 345 .Case("tls", VK_PPC_TLS) 346 .Case("DTPMOD", VK_PPC_DTPMOD) 347 .Case("dtpmod", VK_PPC_DTPMOD) 348 .Case("TPREL", VK_PPC_TPREL) 349 .Case("tprel", VK_PPC_TPREL) 350 .Case("TPREL@L", VK_PPC_TPREL_LO) 351 .Case("tprel@l", VK_PPC_TPREL_LO) 352 .Case("TPREL@H", VK_PPC_TPREL_HI) 353 .Case("tprel@h", VK_PPC_TPREL_HI) 354 .Case("TPREL@HA", VK_PPC_TPREL_HA) 355 .Case("tprel@ha", VK_PPC_TPREL_HA) 356 .Case("TPREL@HIGHER", VK_PPC_TPREL_HIGHER) 357 .Case("tprel@higher", VK_PPC_TPREL_HIGHER) 358 .Case("TPREL@HIGHERA", VK_PPC_TPREL_HIGHERA) 359 .Case("tprel@highera", VK_PPC_TPREL_HIGHERA) 360 .Case("TPREL@HIGHEST", VK_PPC_TPREL_HIGHEST) 361 .Case("tprel@highest", VK_PPC_TPREL_HIGHEST) 362 .Case("TPREL@HIGHESTA", VK_PPC_TPREL_HIGHESTA) 363 .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA) 364 .Case("DTPREL", VK_PPC_DTPREL) 365 .Case("dtprel", VK_PPC_DTPREL) 366 .Case("DTPREL@L", VK_PPC_DTPREL_LO) 367 .Case("dtprel@l", VK_PPC_DTPREL_LO) 368 .Case("DTPREL@H", VK_PPC_DTPREL_HI) 369 .Case("dtprel@h", VK_PPC_DTPREL_HI) 370 .Case("DTPREL@HA", VK_PPC_DTPREL_HA) 371 .Case("dtprel@ha", VK_PPC_DTPREL_HA) 372 .Case("DTPREL@HIGHER", VK_PPC_DTPREL_HIGHER) 373 .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER) 374 .Case("DTPREL@HIGHERA", VK_PPC_DTPREL_HIGHERA) 375 .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA) 376 .Case("DTPREL@HIGHEST", VK_PPC_DTPREL_HIGHEST) 377 .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST) 378 .Case("DTPREL@HIGHESTA", VK_PPC_DTPREL_HIGHESTA) 379 .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA) 380 .Case("GOT@TPREL", VK_PPC_GOT_TPREL) 381 .Case("got@tprel", VK_PPC_GOT_TPREL) 382 .Case("GOT@TPREL@L", VK_PPC_GOT_TPREL_LO) 383 .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO) 384 .Case("GOT@TPREL@H", VK_PPC_GOT_TPREL_HI) 385 .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI) 386 .Case("GOT@TPREL@HA", VK_PPC_GOT_TPREL_HA) 387 .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA) 388 .Case("GOT@DTPREL", VK_PPC_GOT_DTPREL) 389 .Case("got@dtprel", VK_PPC_GOT_DTPREL) 390 .Case("GOT@DTPREL@L", VK_PPC_GOT_DTPREL_LO) 391 .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO) 392 .Case("GOT@DTPREL@H", VK_PPC_GOT_DTPREL_HI) 393 .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI) 394 .Case("GOT@DTPREL@HA", VK_PPC_GOT_DTPREL_HA) 395 .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA) 396 .Case("GOT@TLSGD", VK_PPC_GOT_TLSGD) 397 .Case("got@tlsgd", VK_PPC_GOT_TLSGD) 398 .Case("GOT@TLSGD@L", VK_PPC_GOT_TLSGD_LO) 399 .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO) 400 .Case("GOT@TLSGD@H", VK_PPC_GOT_TLSGD_HI) 401 .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI) 402 .Case("GOT@TLSGD@HA", VK_PPC_GOT_TLSGD_HA) 403 .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA) 404 .Case("GOT@TLSLD", VK_PPC_GOT_TLSLD) 405 .Case("got@tlsld", VK_PPC_GOT_TLSLD) 406 .Case("GOT@TLSLD@L", VK_PPC_GOT_TLSLD_LO) 407 .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO) 408 .Case("GOT@TLSLD@H", VK_PPC_GOT_TLSLD_HI) 409 .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI) 410 .Case("GOT@TLSLD@HA", VK_PPC_GOT_TLSLD_HA) 411 .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA) 412 .Default(VK_Invalid); 413 } 414 415 /* *** */ 416 417 void MCTargetExpr::anchor() {} 418 419 /* *** */ 420 421 bool MCExpr::EvaluateAsAbsolute(int64_t &Res) const { 422 return EvaluateAsAbsolute(Res, 0, 0, 0); 423 } 424 425 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, 426 const MCAsmLayout &Layout) const { 427 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, 0); 428 } 429 430 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, 431 const MCAsmLayout &Layout, 432 const SectionAddrMap &Addrs) const { 433 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs); 434 } 435 436 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const { 437 return EvaluateAsAbsolute(Res, &Asm, 0, 0); 438 } 439 440 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, 441 const MCAsmLayout *Layout, 442 const SectionAddrMap *Addrs) const { 443 MCValue Value; 444 445 // Fast path constants. 446 if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) { 447 Res = CE->getValue(); 448 return true; 449 } 450 451 // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us 452 // absolutize differences across sections and that is what the MachO writer 453 // uses Addrs for. 454 bool IsRelocatable = 455 EvaluateAsRelocatableImpl(Value, Asm, Layout, Addrs, /*InSet*/ Addrs); 456 457 // Record the current value. 458 Res = Value.getConstant(); 459 460 return IsRelocatable && Value.isAbsolute(); 461 } 462 463 /// \brief Helper method for \see EvaluateSymbolAdd(). 464 static void AttemptToFoldSymbolOffsetDifference(const MCAssembler *Asm, 465 const MCAsmLayout *Layout, 466 const SectionAddrMap *Addrs, 467 bool InSet, 468 const MCSymbolRefExpr *&A, 469 const MCSymbolRefExpr *&B, 470 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 MCSymbolData &AD = Asm->getSymbolData(SA); 484 MCSymbolData &BD = Asm->getSymbolData(SB); 485 486 if (AD.getFragment() == BD.getFragment()) { 487 Addend += (AD.getOffset() - BD.getOffset()); 488 489 // Pointers to Thumb symbols need to have their low-bit set to allow 490 // for interworking. 491 if (Asm->isThumbFunc(&SA)) 492 Addend |= 1; 493 494 // Clear the symbol expr pointers to indicate we have folded these 495 // operands. 496 A = B = 0; 497 return; 498 } 499 500 if (!Layout) 501 return; 502 503 const MCSectionData &SecA = *AD.getFragment()->getParent(); 504 const MCSectionData &SecB = *BD.getFragment()->getParent(); 505 506 if ((&SecA != &SecB) && !Addrs) 507 return; 508 509 // Eagerly evaluate. 510 Addend += (Layout->getSymbolOffset(&Asm->getSymbolData(A->getSymbol())) - 511 Layout->getSymbolOffset(&Asm->getSymbolData(B->getSymbol()))); 512 if (Addrs && (&SecA != &SecB)) 513 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB)); 514 515 // Pointers to Thumb symbols need to have their low-bit set to allow 516 // for interworking. 517 if (Asm->isThumbFunc(&SA)) 518 Addend |= 1; 519 520 // Clear the symbol expr pointers to indicate we have folded these 521 // operands. 522 A = B = 0; 523 } 524 525 /// \brief Evaluate the result of an add between (conceptually) two MCValues. 526 /// 527 /// This routine conceptually attempts to construct an MCValue: 528 /// Result = (Result_A - Result_B + Result_Cst) 529 /// from two MCValue's LHS and RHS where 530 /// Result = LHS + RHS 531 /// and 532 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 533 /// 534 /// This routine attempts to aggresively fold the operands such that the result 535 /// is representable in an MCValue, but may not always succeed. 536 /// 537 /// \returns True on success, false if the result is not representable in an 538 /// MCValue. 539 540 /// NOTE: It is really important to have both the Asm and Layout arguments. 541 /// They might look redundant, but this function can be used before layout 542 /// is done (see the object streamer for example) and having the Asm argument 543 /// lets us avoid relaxations early. 544 static bool EvaluateSymbolicAdd(const MCAssembler *Asm, 545 const MCAsmLayout *Layout, 546 const SectionAddrMap *Addrs, 547 bool InSet, 548 const MCValue &LHS,const MCSymbolRefExpr *RHS_A, 549 const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst, 550 MCValue &Res) { 551 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy 552 // about dealing with modifiers. This will ultimately bite us, one day. 553 const MCSymbolRefExpr *LHS_A = LHS.getSymA(); 554 const MCSymbolRefExpr *LHS_B = LHS.getSymB(); 555 int64_t LHS_Cst = LHS.getConstant(); 556 557 // Fold the result constant immediately. 558 int64_t Result_Cst = LHS_Cst + RHS_Cst; 559 560 assert((!Layout || Asm) && 561 "Must have an assembler object if layout is given!"); 562 563 // If we have a layout, we can fold resolved differences. 564 if (Asm) { 565 // First, fold out any differences which are fully resolved. By 566 // reassociating terms in 567 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 568 // we have the four possible differences: 569 // (LHS_A - LHS_B), 570 // (LHS_A - RHS_B), 571 // (RHS_A - LHS_B), 572 // (RHS_A - RHS_B). 573 // Since we are attempting to be as aggressive as possible about folding, we 574 // attempt to evaluate each possible alternative. 575 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B, 576 Result_Cst); 577 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B, 578 Result_Cst); 579 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B, 580 Result_Cst); 581 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B, 582 Result_Cst); 583 } 584 585 // We can't represent the addition or subtraction of two symbols. 586 if ((LHS_A && RHS_A) || (LHS_B && RHS_B)) 587 return false; 588 589 // At this point, we have at most one additive symbol and one subtractive 590 // symbol -- find them. 591 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A; 592 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B; 593 594 // If we have a negated symbol, then we must have also have a non-negated 595 // symbol in order to encode the expression. 596 if (B && !A) 597 return false; 598 599 Res = MCValue::get(A, B, Result_Cst); 600 return true; 601 } 602 603 bool MCExpr::EvaluateAsRelocatable(MCValue &Res, 604 const MCAsmLayout &Layout) const { 605 return EvaluateAsRelocatableImpl(Res, &Layout.getAssembler(), &Layout, 606 0, false); 607 } 608 609 bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res, 610 const MCAssembler *Asm, 611 const MCAsmLayout *Layout, 612 const SectionAddrMap *Addrs, 613 bool InSet) const { 614 ++stats::MCExprEvaluate; 615 616 switch (getKind()) { 617 case Target: 618 return cast<MCTargetExpr>(this)->EvaluateAsRelocatableImpl(Res, Layout); 619 620 case Constant: 621 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue()); 622 return true; 623 624 case SymbolRef: { 625 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 626 const MCSymbol &Sym = SRE->getSymbol(); 627 628 // Evaluate recursively if this is a variable. 629 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) { 630 bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Asm, 631 Layout, 632 Addrs, 633 true); 634 // If we failed to simplify this to a constant, let the target 635 // handle it. 636 if (Ret && !Res.getSymA() && !Res.getSymB()) 637 return true; 638 } 639 640 Res = MCValue::get(SRE, 0, 0); 641 return true; 642 } 643 644 case Unary: { 645 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this); 646 MCValue Value; 647 648 if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Asm, Layout, 649 Addrs, InSet)) 650 return false; 651 652 switch (AUE->getOpcode()) { 653 case MCUnaryExpr::LNot: 654 if (!Value.isAbsolute()) 655 return false; 656 Res = MCValue::get(!Value.getConstant()); 657 break; 658 case MCUnaryExpr::Minus: 659 /// -(a - b + const) ==> (b - a - const) 660 if (Value.getSymA() && !Value.getSymB()) 661 return false; 662 Res = MCValue::get(Value.getSymB(), Value.getSymA(), 663 -Value.getConstant()); 664 break; 665 case MCUnaryExpr::Not: 666 if (!Value.isAbsolute()) 667 return false; 668 Res = MCValue::get(~Value.getConstant()); 669 break; 670 case MCUnaryExpr::Plus: 671 Res = Value; 672 break; 673 } 674 675 return true; 676 } 677 678 case Binary: { 679 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this); 680 MCValue LHSValue, RHSValue; 681 682 if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Asm, Layout, 683 Addrs, InSet) || 684 !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Asm, Layout, 685 Addrs, InSet)) 686 return false; 687 688 // We only support a few operations on non-constant expressions, handle 689 // those first. 690 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) { 691 switch (ABE->getOpcode()) { 692 default: 693 return false; 694 case MCBinaryExpr::Sub: 695 // Negate RHS and add. 696 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 697 RHSValue.getSymB(), RHSValue.getSymA(), 698 -RHSValue.getConstant(), 699 Res); 700 701 case MCBinaryExpr::Add: 702 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 703 RHSValue.getSymA(), RHSValue.getSymB(), 704 RHSValue.getConstant(), 705 Res); 706 } 707 } 708 709 // FIXME: We need target hooks for the evaluation. It may be limited in 710 // width, and gas defines the result of comparisons and right shifts 711 // differently from Apple as. 712 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant(); 713 int64_t Result = 0; 714 switch (ABE->getOpcode()) { 715 case MCBinaryExpr::Add: Result = LHS + RHS; break; 716 case MCBinaryExpr::And: Result = LHS & RHS; break; 717 case MCBinaryExpr::Div: Result = LHS / RHS; break; 718 case MCBinaryExpr::EQ: Result = LHS == RHS; break; 719 case MCBinaryExpr::GT: Result = LHS > RHS; break; 720 case MCBinaryExpr::GTE: Result = LHS >= RHS; break; 721 case MCBinaryExpr::LAnd: Result = LHS && RHS; break; 722 case MCBinaryExpr::LOr: Result = LHS || RHS; break; 723 case MCBinaryExpr::LT: Result = LHS < RHS; break; 724 case MCBinaryExpr::LTE: Result = LHS <= RHS; break; 725 case MCBinaryExpr::Mod: Result = LHS % RHS; break; 726 case MCBinaryExpr::Mul: Result = LHS * RHS; break; 727 case MCBinaryExpr::NE: Result = LHS != RHS; break; 728 case MCBinaryExpr::Or: Result = LHS | RHS; break; 729 case MCBinaryExpr::Shl: Result = LHS << RHS; break; 730 case MCBinaryExpr::Shr: Result = LHS >> RHS; break; 731 case MCBinaryExpr::Sub: Result = LHS - RHS; break; 732 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break; 733 } 734 735 Res = MCValue::get(Result); 736 return true; 737 } 738 } 739 740 llvm_unreachable("Invalid assembly expression kind!"); 741 } 742 743 const MCSection *MCExpr::FindAssociatedSection() const { 744 switch (getKind()) { 745 case Target: 746 // We never look through target specific expressions. 747 return cast<MCTargetExpr>(this)->FindAssociatedSection(); 748 749 case Constant: 750 return MCSymbol::AbsolutePseudoSection; 751 752 case SymbolRef: { 753 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 754 const MCSymbol &Sym = SRE->getSymbol(); 755 756 if (Sym.isDefined()) 757 return &Sym.getSection(); 758 759 return 0; 760 } 761 762 case Unary: 763 return cast<MCUnaryExpr>(this)->getSubExpr()->FindAssociatedSection(); 764 765 case Binary: { 766 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this); 767 const MCSection *LHS_S = BE->getLHS()->FindAssociatedSection(); 768 const MCSection *RHS_S = BE->getRHS()->FindAssociatedSection(); 769 770 // If either section is absolute, return the other. 771 if (LHS_S == MCSymbol::AbsolutePseudoSection) 772 return RHS_S; 773 if (RHS_S == MCSymbol::AbsolutePseudoSection) 774 return LHS_S; 775 776 // Otherwise, return the first non-null section. 777 return LHS_S ? LHS_S : RHS_S; 778 } 779 } 780 781 llvm_unreachable("Invalid assembly expression kind!"); 782 } 783
