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/MCAsmInfo.h" 15 #include "llvm/MC/MCAsmLayout.h" 16 #include "llvm/MC/MCAssembler.h" 17 #include "llvm/MC/MCContext.h" 18 #include "llvm/MC/MCObjectWriter.h" 19 #include "llvm/MC/MCSymbol.h" 20 #include "llvm/MC/MCValue.h" 21 #include "llvm/Support/Debug.h" 22 #include "llvm/Support/ErrorHandling.h" 23 #include "llvm/Support/raw_ostream.h" 24 using namespace llvm; 25 26 namespace { 27 namespace stats { 28 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations"); 29 } 30 } 31 32 void MCExpr::print(raw_ostream &OS) const { 33 switch (getKind()) { 34 case MCExpr::Target: 35 return cast<MCTargetExpr>(this)->PrintImpl(OS); 36 case MCExpr::Constant: 37 OS << cast<MCConstantExpr>(*this).getValue(); 38 return; 39 40 case MCExpr::SymbolRef: { 41 const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this); 42 const MCSymbol &Sym = SRE.getSymbol(); 43 // Parenthesize names that start with $ so that they don't look like 44 // absolute names. 45 bool UseParens = Sym.getName()[0] == '$'; 46 if (UseParens) 47 OS << '(' << Sym << ')'; 48 else 49 OS << Sym; 50 51 if (SRE.getKind() != MCSymbolRefExpr::VK_None) { 52 if (SRE.getMCAsmInfo().useParensForSymbolVariant()) 53 OS << '(' << MCSymbolRefExpr::getVariantKindName(SRE.getKind()) << ')'; 54 else 55 OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind()); 56 } 57 58 return; 59 } 60 61 case MCExpr::Unary: { 62 const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this); 63 switch (UE.getOpcode()) { 64 case MCUnaryExpr::LNot: OS << '!'; break; 65 case MCUnaryExpr::Minus: OS << '-'; break; 66 case MCUnaryExpr::Not: OS << '~'; break; 67 case MCUnaryExpr::Plus: OS << '+'; break; 68 } 69 OS << *UE.getSubExpr(); 70 return; 71 } 72 73 case MCExpr::Binary: { 74 const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this); 75 76 // Only print parens around the LHS if it is non-trivial. 77 if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) { 78 OS << *BE.getLHS(); 79 } else { 80 OS << '(' << *BE.getLHS() << ')'; 81 } 82 83 switch (BE.getOpcode()) { 84 case MCBinaryExpr::Add: 85 // Print "X-42" instead of "X+-42". 86 if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) { 87 if (RHSC->getValue() < 0) { 88 OS << RHSC->getValue(); 89 return; 90 } 91 } 92 93 OS << '+'; 94 break; 95 case MCBinaryExpr::And: OS << '&'; break; 96 case MCBinaryExpr::Div: OS << '/'; break; 97 case MCBinaryExpr::EQ: OS << "=="; break; 98 case MCBinaryExpr::GT: OS << '>'; break; 99 case MCBinaryExpr::GTE: OS << ">="; break; 100 case MCBinaryExpr::LAnd: OS << "&&"; break; 101 case MCBinaryExpr::LOr: OS << "||"; break; 102 case MCBinaryExpr::LT: OS << '<'; break; 103 case MCBinaryExpr::LTE: OS << "<="; break; 104 case MCBinaryExpr::Mod: OS << '%'; break; 105 case MCBinaryExpr::Mul: OS << '*'; break; 106 case MCBinaryExpr::NE: OS << "!="; break; 107 case MCBinaryExpr::Or: OS << '|'; break; 108 case MCBinaryExpr::Shl: OS << "<<"; break; 109 case MCBinaryExpr::Shr: OS << ">>"; break; 110 case MCBinaryExpr::Sub: OS << '-'; break; 111 case MCBinaryExpr::Xor: OS << '^'; break; 112 } 113 114 // Only print parens around the LHS if it is non-trivial. 115 if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) { 116 OS << *BE.getRHS(); 117 } else { 118 OS << '(' << *BE.getRHS() << ')'; 119 } 120 return; 121 } 122 } 123 124 llvm_unreachable("Invalid expression kind!"); 125 } 126 127 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 128 void MCExpr::dump() const { 129 print(dbgs()); 130 dbgs() << '\n'; 131 } 132 #endif 133 134 /* *** */ 135 136 const MCBinaryExpr *MCBinaryExpr::Create(Opcode Opc, const MCExpr *LHS, 137 const MCExpr *RHS, MCContext &Ctx) { 138 return new (Ctx) MCBinaryExpr(Opc, LHS, RHS); 139 } 140 141 const MCUnaryExpr *MCUnaryExpr::Create(Opcode Opc, const MCExpr *Expr, 142 MCContext &Ctx) { 143 return new (Ctx) MCUnaryExpr(Opc, Expr); 144 } 145 146 const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) { 147 return new (Ctx) MCConstantExpr(Value); 148 } 149 150 /* *** */ 151 152 const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym, 153 VariantKind Kind, 154 MCContext &Ctx) { 155 return new (Ctx) MCSymbolRefExpr(Sym, Kind, Ctx.getAsmInfo()); 156 } 157 158 const MCSymbolRefExpr *MCSymbolRefExpr::Create(StringRef Name, VariantKind Kind, 159 MCContext &Ctx) { 160 return Create(Ctx.GetOrCreateSymbol(Name), Kind, Ctx); 161 } 162 163 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) { 164 switch (Kind) { 165 case VK_Invalid: return "<<invalid>>"; 166 case VK_None: return "<<none>>"; 167 168 case VK_GOT: return "GOT"; 169 case VK_GOTOFF: return "GOTOFF"; 170 case VK_GOTPCREL: return "GOTPCREL"; 171 case VK_GOTTPOFF: return "GOTTPOFF"; 172 case VK_INDNTPOFF: return "INDNTPOFF"; 173 case VK_NTPOFF: return "NTPOFF"; 174 case VK_GOTNTPOFF: return "GOTNTPOFF"; 175 case VK_PLT: return "PLT"; 176 case VK_TLSGD: return "TLSGD"; 177 case VK_TLSLD: return "TLSLD"; 178 case VK_TLSLDM: return "TLSLDM"; 179 case VK_TPOFF: return "TPOFF"; 180 case VK_DTPOFF: return "DTPOFF"; 181 case VK_TLVP: return "TLVP"; 182 case VK_SECREL: return "SECREL32"; 183 case VK_ARM_NONE: return "none"; 184 case VK_ARM_TARGET1: return "target1"; 185 case VK_ARM_TARGET2: return "target2"; 186 case VK_ARM_PREL31: return "prel31"; 187 case VK_ARM_TLSLDO: return "tlsldo"; 188 case VK_ARM_TLSCALL: return "tlscall"; 189 case VK_ARM_TLSDESC: return "tlsdesc"; 190 case VK_ARM_TLSDESCSEQ: return "tlsdescseq"; 191 case VK_PPC_LO: return "l"; 192 case VK_PPC_HI: return "h"; 193 case VK_PPC_HA: return "ha"; 194 case VK_PPC_HIGHER: return "higher"; 195 case VK_PPC_HIGHERA: return "highera"; 196 case VK_PPC_HIGHEST: return "highest"; 197 case VK_PPC_HIGHESTA: return "highesta"; 198 case VK_PPC_GOT_LO: return "got@l"; 199 case VK_PPC_GOT_HI: return "got@h"; 200 case VK_PPC_GOT_HA: return "got@ha"; 201 case VK_PPC_TOCBASE: return "tocbase"; 202 case VK_PPC_TOC: return "toc"; 203 case VK_PPC_TOC_LO: return "toc@l"; 204 case VK_PPC_TOC_HI: return "toc@h"; 205 case VK_PPC_TOC_HA: return "toc@ha"; 206 case VK_PPC_DTPMOD: return "dtpmod"; 207 case VK_PPC_TPREL: return "tprel"; 208 case VK_PPC_TPREL_LO: return "tprel@l"; 209 case VK_PPC_TPREL_HI: return "tprel@h"; 210 case VK_PPC_TPREL_HA: return "tprel@ha"; 211 case VK_PPC_TPREL_HIGHER: return "tprel@higher"; 212 case VK_PPC_TPREL_HIGHERA: return "tprel@highera"; 213 case VK_PPC_TPREL_HIGHEST: return "tprel@highest"; 214 case VK_PPC_TPREL_HIGHESTA: return "tprel@highesta"; 215 case VK_PPC_DTPREL: return "dtprel"; 216 case VK_PPC_DTPREL_LO: return "dtprel@l"; 217 case VK_PPC_DTPREL_HI: return "dtprel@h"; 218 case VK_PPC_DTPREL_HA: return "dtprel@ha"; 219 case VK_PPC_DTPREL_HIGHER: return "dtprel@higher"; 220 case VK_PPC_DTPREL_HIGHERA: return "dtprel@highera"; 221 case VK_PPC_DTPREL_HIGHEST: return "dtprel@highest"; 222 case VK_PPC_DTPREL_HIGHESTA: return "dtprel@highesta"; 223 case VK_PPC_GOT_TPREL: return "got@tprel"; 224 case VK_PPC_GOT_TPREL_LO: return "got@tprel@l"; 225 case VK_PPC_GOT_TPREL_HI: return "got@tprel@h"; 226 case VK_PPC_GOT_TPREL_HA: return "got@tprel@ha"; 227 case VK_PPC_GOT_DTPREL: return "got@dtprel"; 228 case VK_PPC_GOT_DTPREL_LO: return "got@dtprel@l"; 229 case VK_PPC_GOT_DTPREL_HI: return "got@dtprel@h"; 230 case VK_PPC_GOT_DTPREL_HA: return "got@dtprel@ha"; 231 case VK_PPC_TLS: return "tls"; 232 case VK_PPC_GOT_TLSGD: return "got@tlsgd"; 233 case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l"; 234 case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h"; 235 case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha"; 236 case VK_PPC_TLSGD: return "tlsgd"; 237 case VK_PPC_GOT_TLSLD: return "got@tlsld"; 238 case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l"; 239 case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h"; 240 case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha"; 241 case VK_PPC_TLSLD: return "tlsld"; 242 case VK_Mips_GPREL: return "GPREL"; 243 case VK_Mips_GOT_CALL: return "GOT_CALL"; 244 case VK_Mips_GOT16: return "GOT16"; 245 case VK_Mips_GOT: return "GOT"; 246 case VK_Mips_ABS_HI: return "ABS_HI"; 247 case VK_Mips_ABS_LO: return "ABS_LO"; 248 case VK_Mips_TLSGD: return "TLSGD"; 249 case VK_Mips_TLSLDM: return "TLSLDM"; 250 case VK_Mips_DTPREL_HI: return "DTPREL_HI"; 251 case VK_Mips_DTPREL_LO: return "DTPREL_LO"; 252 case VK_Mips_GOTTPREL: return "GOTTPREL"; 253 case VK_Mips_TPREL_HI: return "TPREL_HI"; 254 case VK_Mips_TPREL_LO: return "TPREL_LO"; 255 case VK_Mips_GPOFF_HI: return "GPOFF_HI"; 256 case VK_Mips_GPOFF_LO: return "GPOFF_LO"; 257 case VK_Mips_GOT_DISP: return "GOT_DISP"; 258 case VK_Mips_GOT_PAGE: return "GOT_PAGE"; 259 case VK_Mips_GOT_OFST: return "GOT_OFST"; 260 case VK_Mips_HIGHER: return "HIGHER"; 261 case VK_Mips_HIGHEST: return "HIGHEST"; 262 case VK_Mips_GOT_HI16: return "GOT_HI16"; 263 case VK_Mips_GOT_LO16: return "GOT_LO16"; 264 case VK_Mips_CALL_HI16: return "CALL_HI16"; 265 case VK_Mips_CALL_LO16: return "CALL_LO16"; 266 case VK_COFF_IMGREL32: return "IMGREL32"; 267 } 268 llvm_unreachable("Invalid variant kind"); 269 } 270 271 MCSymbolRefExpr::VariantKind 272 MCSymbolRefExpr::getVariantKindForName(StringRef Name) { 273 return StringSwitch<VariantKind>(Name) 274 .Case("GOT", VK_GOT) 275 .Case("got", VK_GOT) 276 .Case("GOTOFF", VK_GOTOFF) 277 .Case("gotoff", VK_GOTOFF) 278 .Case("GOTPCREL", VK_GOTPCREL) 279 .Case("gotpcrel", VK_GOTPCREL) 280 .Case("GOTTPOFF", VK_GOTTPOFF) 281 .Case("gottpoff", VK_GOTTPOFF) 282 .Case("INDNTPOFF", VK_INDNTPOFF) 283 .Case("indntpoff", VK_INDNTPOFF) 284 .Case("NTPOFF", VK_NTPOFF) 285 .Case("ntpoff", VK_NTPOFF) 286 .Case("GOTNTPOFF", VK_GOTNTPOFF) 287 .Case("gotntpoff", VK_GOTNTPOFF) 288 .Case("PLT", VK_PLT) 289 .Case("plt", VK_PLT) 290 .Case("TLSGD", VK_TLSGD) 291 .Case("tlsgd", VK_TLSGD) 292 .Case("TLSLD", VK_TLSLD) 293 .Case("tlsld", VK_TLSLD) 294 .Case("TLSLDM", VK_TLSLDM) 295 .Case("tlsldm", VK_TLSLDM) 296 .Case("TPOFF", VK_TPOFF) 297 .Case("tpoff", VK_TPOFF) 298 .Case("DTPOFF", VK_DTPOFF) 299 .Case("dtpoff", VK_DTPOFF) 300 .Case("TLVP", VK_TLVP) 301 .Case("tlvp", VK_TLVP) 302 .Case("IMGREL", VK_COFF_IMGREL32) 303 .Case("imgrel", VK_COFF_IMGREL32) 304 .Case("SECREL32", VK_SECREL) 305 .Case("secrel32", VK_SECREL) 306 .Case("L", VK_PPC_LO) 307 .Case("l", VK_PPC_LO) 308 .Case("H", VK_PPC_HI) 309 .Case("h", VK_PPC_HI) 310 .Case("HA", VK_PPC_HA) 311 .Case("ha", VK_PPC_HA) 312 .Case("HIGHER", VK_PPC_HIGHER) 313 .Case("higher", VK_PPC_HIGHER) 314 .Case("HIGHERA", VK_PPC_HIGHERA) 315 .Case("highera", VK_PPC_HIGHERA) 316 .Case("HIGHEST", VK_PPC_HIGHEST) 317 .Case("highest", VK_PPC_HIGHEST) 318 .Case("HIGHESTA", VK_PPC_HIGHESTA) 319 .Case("highesta", VK_PPC_HIGHESTA) 320 .Case("GOT@L", VK_PPC_GOT_LO) 321 .Case("got@l", VK_PPC_GOT_LO) 322 .Case("GOT@H", VK_PPC_GOT_HI) 323 .Case("got@h", VK_PPC_GOT_HI) 324 .Case("GOT@HA", VK_PPC_GOT_HA) 325 .Case("got@ha", VK_PPC_GOT_HA) 326 .Case("TOCBASE", VK_PPC_TOCBASE) 327 .Case("tocbase", VK_PPC_TOCBASE) 328 .Case("TOC", VK_PPC_TOC) 329 .Case("toc", VK_PPC_TOC) 330 .Case("TOC@L", VK_PPC_TOC_LO) 331 .Case("toc@l", VK_PPC_TOC_LO) 332 .Case("TOC@H", VK_PPC_TOC_HI) 333 .Case("toc@h", VK_PPC_TOC_HI) 334 .Case("TOC@HA", VK_PPC_TOC_HA) 335 .Case("toc@ha", VK_PPC_TOC_HA) 336 .Case("TLS", VK_PPC_TLS) 337 .Case("tls", VK_PPC_TLS) 338 .Case("DTPMOD", VK_PPC_DTPMOD) 339 .Case("dtpmod", VK_PPC_DTPMOD) 340 .Case("TPREL", VK_PPC_TPREL) 341 .Case("tprel", VK_PPC_TPREL) 342 .Case("TPREL@L", VK_PPC_TPREL_LO) 343 .Case("tprel@l", VK_PPC_TPREL_LO) 344 .Case("TPREL@H", VK_PPC_TPREL_HI) 345 .Case("tprel@h", VK_PPC_TPREL_HI) 346 .Case("TPREL@HA", VK_PPC_TPREL_HA) 347 .Case("tprel@ha", VK_PPC_TPREL_HA) 348 .Case("TPREL@HIGHER", VK_PPC_TPREL_HIGHER) 349 .Case("tprel@higher", VK_PPC_TPREL_HIGHER) 350 .Case("TPREL@HIGHERA", VK_PPC_TPREL_HIGHERA) 351 .Case("tprel@highera", VK_PPC_TPREL_HIGHERA) 352 .Case("TPREL@HIGHEST", VK_PPC_TPREL_HIGHEST) 353 .Case("tprel@highest", VK_PPC_TPREL_HIGHEST) 354 .Case("TPREL@HIGHESTA", VK_PPC_TPREL_HIGHESTA) 355 .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA) 356 .Case("DTPREL", VK_PPC_DTPREL) 357 .Case("dtprel", VK_PPC_DTPREL) 358 .Case("DTPREL@L", VK_PPC_DTPREL_LO) 359 .Case("dtprel@l", VK_PPC_DTPREL_LO) 360 .Case("DTPREL@H", VK_PPC_DTPREL_HI) 361 .Case("dtprel@h", VK_PPC_DTPREL_HI) 362 .Case("DTPREL@HA", VK_PPC_DTPREL_HA) 363 .Case("dtprel@ha", VK_PPC_DTPREL_HA) 364 .Case("DTPREL@HIGHER", VK_PPC_DTPREL_HIGHER) 365 .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER) 366 .Case("DTPREL@HIGHERA", VK_PPC_DTPREL_HIGHERA) 367 .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA) 368 .Case("DTPREL@HIGHEST", VK_PPC_DTPREL_HIGHEST) 369 .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST) 370 .Case("DTPREL@HIGHESTA", VK_PPC_DTPREL_HIGHESTA) 371 .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA) 372 .Case("GOT@TPREL", VK_PPC_GOT_TPREL) 373 .Case("got@tprel", VK_PPC_GOT_TPREL) 374 .Case("GOT@TPREL@L", VK_PPC_GOT_TPREL_LO) 375 .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO) 376 .Case("GOT@TPREL@H", VK_PPC_GOT_TPREL_HI) 377 .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI) 378 .Case("GOT@TPREL@HA", VK_PPC_GOT_TPREL_HA) 379 .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA) 380 .Case("GOT@DTPREL", VK_PPC_GOT_DTPREL) 381 .Case("got@dtprel", VK_PPC_GOT_DTPREL) 382 .Case("GOT@DTPREL@L", VK_PPC_GOT_DTPREL_LO) 383 .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO) 384 .Case("GOT@DTPREL@H", VK_PPC_GOT_DTPREL_HI) 385 .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI) 386 .Case("GOT@DTPREL@HA", VK_PPC_GOT_DTPREL_HA) 387 .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA) 388 .Case("GOT@TLSGD", VK_PPC_GOT_TLSGD) 389 .Case("got@tlsgd", VK_PPC_GOT_TLSGD) 390 .Case("GOT@TLSGD@L", VK_PPC_GOT_TLSGD_LO) 391 .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO) 392 .Case("GOT@TLSGD@H", VK_PPC_GOT_TLSGD_HI) 393 .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI) 394 .Case("GOT@TLSGD@HA", VK_PPC_GOT_TLSGD_HA) 395 .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA) 396 .Case("GOT@TLSLD", VK_PPC_GOT_TLSLD) 397 .Case("got@tlsld", VK_PPC_GOT_TLSLD) 398 .Case("GOT@TLSLD@L", VK_PPC_GOT_TLSLD_LO) 399 .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO) 400 .Case("GOT@TLSLD@H", VK_PPC_GOT_TLSLD_HI) 401 .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI) 402 .Case("GOT@TLSLD@HA", VK_PPC_GOT_TLSLD_HA) 403 .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA) 404 .Case("NONE", VK_ARM_NONE) 405 .Case("none", VK_ARM_NONE) 406 .Case("TARGET1", VK_ARM_TARGET1) 407 .Case("target1", VK_ARM_TARGET1) 408 .Case("TARGET2", VK_ARM_TARGET2) 409 .Case("target2", VK_ARM_TARGET2) 410 .Case("PREL31", VK_ARM_PREL31) 411 .Case("prel31", VK_ARM_PREL31) 412 .Case("TLSLDO", VK_ARM_TLSLDO) 413 .Case("tlsldo", VK_ARM_TLSLDO) 414 .Case("TLSCALL", VK_ARM_TLSCALL) 415 .Case("tlscall", VK_ARM_TLSCALL) 416 .Case("TLSDESC", VK_ARM_TLSDESC) 417 .Case("tlsdesc", VK_ARM_TLSDESC) 418 .Default(VK_Invalid); 419 } 420 421 /* *** */ 422 423 void MCTargetExpr::anchor() {} 424 425 /* *** */ 426 427 bool MCExpr::EvaluateAsAbsolute(int64_t &Res) const { 428 return EvaluateAsAbsolute(Res, 0, 0, 0); 429 } 430 431 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, 432 const MCAsmLayout &Layout) const { 433 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, 0); 434 } 435 436 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, 437 const MCAsmLayout &Layout, 438 const SectionAddrMap &Addrs) const { 439 return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs); 440 } 441 442 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const { 443 return EvaluateAsAbsolute(Res, &Asm, 0, 0); 444 } 445 446 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, 447 const MCAsmLayout *Layout, 448 const SectionAddrMap *Addrs) 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 // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us 458 // absolutize differences across sections and that is what the MachO writer 459 // uses Addrs for. 460 bool IsRelocatable = 461 EvaluateAsRelocatableImpl(Value, Asm, Layout, Addrs, /*InSet*/ Addrs); 462 463 // Record the current value. 464 Res = Value.getConstant(); 465 466 return IsRelocatable && Value.isAbsolute(); 467 } 468 469 /// \brief Helper method for \see EvaluateSymbolAdd(). 470 static void AttemptToFoldSymbolOffsetDifference(const MCAssembler *Asm, 471 const MCAsmLayout *Layout, 472 const SectionAddrMap *Addrs, 473 bool InSet, 474 const MCSymbolRefExpr *&A, 475 const MCSymbolRefExpr *&B, 476 int64_t &Addend) { 477 if (!A || !B) 478 return; 479 480 const MCSymbol &SA = A->getSymbol(); 481 const MCSymbol &SB = B->getSymbol(); 482 483 if (SA.isUndefined() || SB.isUndefined()) 484 return; 485 486 if (!Asm->getWriter().IsSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet)) 487 return; 488 489 MCSymbolData &AD = Asm->getSymbolData(SA); 490 MCSymbolData &BD = Asm->getSymbolData(SB); 491 492 if (AD.getFragment() == BD.getFragment()) { 493 Addend += (AD.getOffset() - BD.getOffset()); 494 495 // Pointers to Thumb symbols need to have their low-bit set to allow 496 // for interworking. 497 if (Asm->isThumbFunc(&SA)) 498 Addend |= 1; 499 500 // Clear the symbol expr pointers to indicate we have folded these 501 // operands. 502 A = B = 0; 503 return; 504 } 505 506 if (!Layout) 507 return; 508 509 const MCSectionData &SecA = *AD.getFragment()->getParent(); 510 const MCSectionData &SecB = *BD.getFragment()->getParent(); 511 512 if ((&SecA != &SecB) && !Addrs) 513 return; 514 515 // Eagerly evaluate. 516 Addend += (Layout->getSymbolOffset(&Asm->getSymbolData(A->getSymbol())) - 517 Layout->getSymbolOffset(&Asm->getSymbolData(B->getSymbol()))); 518 if (Addrs && (&SecA != &SecB)) 519 Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB)); 520 521 // Pointers to Thumb symbols need to have their low-bit set to allow 522 // for interworking. 523 if (Asm->isThumbFunc(&SA)) 524 Addend |= 1; 525 526 // Clear the symbol expr pointers to indicate we have folded these 527 // operands. 528 A = B = 0; 529 } 530 531 /// \brief Evaluate the result of an add between (conceptually) two MCValues. 532 /// 533 /// This routine conceptually attempts to construct an MCValue: 534 /// Result = (Result_A - Result_B + Result_Cst) 535 /// from two MCValue's LHS and RHS where 536 /// Result = LHS + RHS 537 /// and 538 /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 539 /// 540 /// This routine attempts to aggresively fold the operands such that the result 541 /// is representable in an MCValue, but may not always succeed. 542 /// 543 /// \returns True on success, false if the result is not representable in an 544 /// MCValue. 545 546 /// NOTE: It is really important to have both the Asm and Layout arguments. 547 /// They might look redundant, but this function can be used before layout 548 /// is done (see the object streamer for example) and having the Asm argument 549 /// lets us avoid relaxations early. 550 static bool EvaluateSymbolicAdd(const MCAssembler *Asm, 551 const MCAsmLayout *Layout, 552 const SectionAddrMap *Addrs, 553 bool InSet, 554 const MCValue &LHS,const MCSymbolRefExpr *RHS_A, 555 const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst, 556 MCValue &Res) { 557 // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy 558 // about dealing with modifiers. This will ultimately bite us, one day. 559 const MCSymbolRefExpr *LHS_A = LHS.getSymA(); 560 const MCSymbolRefExpr *LHS_B = LHS.getSymB(); 561 int64_t LHS_Cst = LHS.getConstant(); 562 563 // Fold the result constant immediately. 564 int64_t Result_Cst = LHS_Cst + RHS_Cst; 565 566 assert((!Layout || Asm) && 567 "Must have an assembler object if layout is given!"); 568 569 // If we have a layout, we can fold resolved differences. 570 if (Asm) { 571 // First, fold out any differences which are fully resolved. By 572 // reassociating terms in 573 // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). 574 // we have the four possible differences: 575 // (LHS_A - LHS_B), 576 // (LHS_A - RHS_B), 577 // (RHS_A - LHS_B), 578 // (RHS_A - RHS_B). 579 // Since we are attempting to be as aggressive as possible about folding, we 580 // attempt to evaluate each possible alternative. 581 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B, 582 Result_Cst); 583 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B, 584 Result_Cst); 585 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B, 586 Result_Cst); 587 AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B, 588 Result_Cst); 589 } 590 591 // We can't represent the addition or subtraction of two symbols. 592 if ((LHS_A && RHS_A) || (LHS_B && RHS_B)) 593 return false; 594 595 // At this point, we have at most one additive symbol and one subtractive 596 // symbol -- find them. 597 const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A; 598 const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B; 599 600 // If we have a negated symbol, then we must have also have a non-negated 601 // symbol in order to encode the expression. 602 if (B && !A) 603 return false; 604 605 Res = MCValue::get(A, B, Result_Cst); 606 return true; 607 } 608 609 bool MCExpr::EvaluateAsRelocatable(MCValue &Res, 610 const MCAsmLayout &Layout) const { 611 return EvaluateAsRelocatableImpl(Res, &Layout.getAssembler(), &Layout, 612 0, false); 613 } 614 615 bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res, 616 const MCAssembler *Asm, 617 const MCAsmLayout *Layout, 618 const SectionAddrMap *Addrs, 619 bool InSet) const { 620 ++stats::MCExprEvaluate; 621 622 switch (getKind()) { 623 case Target: 624 return cast<MCTargetExpr>(this)->EvaluateAsRelocatableImpl(Res, Layout); 625 626 case Constant: 627 Res = MCValue::get(cast<MCConstantExpr>(this)->getValue()); 628 return true; 629 630 case SymbolRef: { 631 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 632 const MCSymbol &Sym = SRE->getSymbol(); 633 634 // Evaluate recursively if this is a variable. 635 if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) { 636 bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Asm, 637 Layout, 638 Addrs, 639 true); 640 // If we failed to simplify this to a constant, let the target 641 // handle it. 642 if (Ret && !Res.getSymA() && !Res.getSymB()) 643 return true; 644 } 645 646 Res = MCValue::get(SRE, 0, 0); 647 return true; 648 } 649 650 case Unary: { 651 const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this); 652 MCValue Value; 653 654 if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Asm, Layout, 655 Addrs, InSet)) 656 return false; 657 658 switch (AUE->getOpcode()) { 659 case MCUnaryExpr::LNot: 660 if (!Value.isAbsolute()) 661 return false; 662 Res = MCValue::get(!Value.getConstant()); 663 break; 664 case MCUnaryExpr::Minus: 665 /// -(a - b + const) ==> (b - a - const) 666 if (Value.getSymA() && !Value.getSymB()) 667 return false; 668 Res = MCValue::get(Value.getSymB(), Value.getSymA(), 669 -Value.getConstant()); 670 break; 671 case MCUnaryExpr::Not: 672 if (!Value.isAbsolute()) 673 return false; 674 Res = MCValue::get(~Value.getConstant()); 675 break; 676 case MCUnaryExpr::Plus: 677 Res = Value; 678 break; 679 } 680 681 return true; 682 } 683 684 case Binary: { 685 const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this); 686 MCValue LHSValue, RHSValue; 687 688 if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Asm, Layout, 689 Addrs, InSet) || 690 !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Asm, Layout, 691 Addrs, InSet)) 692 return false; 693 694 // We only support a few operations on non-constant expressions, handle 695 // those first. 696 if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) { 697 switch (ABE->getOpcode()) { 698 default: 699 return false; 700 case MCBinaryExpr::Sub: 701 // Negate RHS and add. 702 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 703 RHSValue.getSymB(), RHSValue.getSymA(), 704 -RHSValue.getConstant(), 705 Res); 706 707 case MCBinaryExpr::Add: 708 return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, 709 RHSValue.getSymA(), RHSValue.getSymB(), 710 RHSValue.getConstant(), 711 Res); 712 } 713 } 714 715 // FIXME: We need target hooks for the evaluation. It may be limited in 716 // width, and gas defines the result of comparisons and right shifts 717 // differently from Apple as. 718 int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant(); 719 int64_t Result = 0; 720 switch (ABE->getOpcode()) { 721 case MCBinaryExpr::Add: Result = LHS + RHS; break; 722 case MCBinaryExpr::And: Result = LHS & RHS; break; 723 case MCBinaryExpr::Div: Result = LHS / RHS; break; 724 case MCBinaryExpr::EQ: Result = LHS == RHS; break; 725 case MCBinaryExpr::GT: Result = LHS > RHS; break; 726 case MCBinaryExpr::GTE: Result = LHS >= RHS; break; 727 case MCBinaryExpr::LAnd: Result = LHS && RHS; break; 728 case MCBinaryExpr::LOr: Result = LHS || RHS; break; 729 case MCBinaryExpr::LT: Result = LHS < RHS; break; 730 case MCBinaryExpr::LTE: Result = LHS <= RHS; break; 731 case MCBinaryExpr::Mod: Result = LHS % RHS; break; 732 case MCBinaryExpr::Mul: Result = LHS * RHS; break; 733 case MCBinaryExpr::NE: Result = LHS != RHS; break; 734 case MCBinaryExpr::Or: Result = LHS | RHS; break; 735 case MCBinaryExpr::Shl: Result = LHS << RHS; break; 736 case MCBinaryExpr::Shr: Result = LHS >> RHS; break; 737 case MCBinaryExpr::Sub: Result = LHS - RHS; break; 738 case MCBinaryExpr::Xor: Result = LHS ^ RHS; break; 739 } 740 741 Res = MCValue::get(Result); 742 return true; 743 } 744 } 745 746 llvm_unreachable("Invalid assembly expression kind!"); 747 } 748 749 const MCSection *MCExpr::FindAssociatedSection() const { 750 switch (getKind()) { 751 case Target: 752 // We never look through target specific expressions. 753 return cast<MCTargetExpr>(this)->FindAssociatedSection(); 754 755 case Constant: 756 return MCSymbol::AbsolutePseudoSection; 757 758 case SymbolRef: { 759 const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); 760 const MCSymbol &Sym = SRE->getSymbol(); 761 762 if (Sym.isDefined()) 763 return &Sym.getSection(); 764 765 return 0; 766 } 767 768 case Unary: 769 return cast<MCUnaryExpr>(this)->getSubExpr()->FindAssociatedSection(); 770 771 case Binary: { 772 const MCBinaryExpr *BE = cast<MCBinaryExpr>(this); 773 const MCSection *LHS_S = BE->getLHS()->FindAssociatedSection(); 774 const MCSection *RHS_S = BE->getRHS()->FindAssociatedSection(); 775 776 // If either section is absolute, return the other. 777 if (LHS_S == MCSymbol::AbsolutePseudoSection) 778 return RHS_S; 779 if (RHS_S == MCSymbol::AbsolutePseudoSection) 780 return LHS_S; 781 782 // Otherwise, return the first non-null section. 783 return LHS_S ? LHS_S : RHS_S; 784 } 785 } 786 787 llvm_unreachable("Invalid assembly expression kind!"); 788 } 789