lib/MC/MCExpr.cpp

   1 //===- MCExpr.cpp - Assembly Level Expression Implementation --------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/MC/MCExpr.h"
  10 #include "llvm/ADT/Statistic.h"
  11 #include "llvm/ADT/StringSwitch.h"
  12 #include "llvm/Config/llvm-config.h"
  13 #include "llvm/MC/MCAsmBackend.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/Casting.h"
  22 #include "llvm/Support/Compiler.h"
  23 #include "llvm/Support/Debug.h"
  24 #include "llvm/Support/ErrorHandling.h"
  25 #include "llvm/Support/raw_ostream.h"
  26 #include <cassert>
  27 #include <cstdint>
  28
  29 using namespace llvm;
  30
  31 #define DEBUG_TYPE "mcexpr"
  32
  33 namespace {
  34 namespace stats {
  35
  36 STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations");
  37
  38 } // end namespace stats
  39 } // end anonymous namespace
  40
  41 void MCExpr::print(raw_ostream &OS, const MCAsmInfo *MAI, bool InParens) const {
  42   switch (getKind()) {
  43   case MCExpr::Target:
  44     return cast<MCTargetExpr>(this)->printImpl(OS, MAI);
  45   case MCExpr::Constant:
  46     OS << cast<MCConstantExpr>(*this).getValue();
  47     return;
  48
  49   case MCExpr::SymbolRef: {
  50     const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this);
  51     const MCSymbol &Sym = SRE.getSymbol();
  52     // Parenthesize names that start with $ so that they don't look like
  53     // absolute names.
  54     bool UseParens =
  55         !InParens && !Sym.getName().empty() && Sym.getName()[0] == '$';
  56     if (UseParens) {
  57       OS << '(';
  58       Sym.print(OS, MAI);
  59       OS << ')';
  60     } else
  61       Sym.print(OS, MAI);
  62
  63     if (SRE.getKind() != MCSymbolRefExpr::VK_None)
  64       SRE.printVariantKind(OS);
  65
  66     return;
  67   }
  68
  69   case MCExpr::Unary: {
  70     const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this);
  71     switch (UE.getOpcode()) {
  72     case MCUnaryExpr::LNot:  OS << '!'; break;
  73     case MCUnaryExpr::Minus: OS << '-'; break;
  74     case MCUnaryExpr::Not:   OS << '~'; break;
  75     case MCUnaryExpr::Plus:  OS << '+'; break;
  76     }
  77     bool Binary = UE.getSubExpr()->getKind() == MCExpr::Binary;
  78     if (Binary) OS << "(";
  79     UE.getSubExpr()->print(OS, MAI);
  80     if (Binary) OS << ")";
  81     return;
  82   }
  83
  84   case MCExpr::Binary: {
  85     const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this);
  86
  87     // Only print parens around the LHS if it is non-trivial.
  88     if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) {
  89       BE.getLHS()->print(OS, MAI);
  90     } else {
  91       OS << '(';
  92       BE.getLHS()->print(OS, MAI);
  93       OS << ')';
  94     }
  95
  96     switch (BE.getOpcode()) {
  97     case MCBinaryExpr::Add:
  98       // Print "X-42" instead of "X+-42".
  99       if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) {
 100         if (RHSC->getValue() < 0) {
 101           OS << RHSC->getValue();
 102           return;
 103         }
 104       }
 105
 106       OS <<  '+';
 107       break;
 108     case MCBinaryExpr::AShr: OS << ">>"; break;
 109     case MCBinaryExpr::And:  OS <<  '&'; break;
 110     case MCBinaryExpr::Div:  OS <<  '/'; break;
 111     case MCBinaryExpr::EQ:   OS << "=="; break;
 112     case MCBinaryExpr::GT:   OS <<  '>'; break;
 113     case MCBinaryExpr::GTE:  OS << ">="; break;
 114     case MCBinaryExpr::LAnd: OS << "&&"; break;
 115     case MCBinaryExpr::LOr:  OS << "||"; break;
 116     case MCBinaryExpr::LShr: 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::Sub:  OS <<  '-'; break;
 125     case MCBinaryExpr::Xor:  OS <<  '^'; break;
 126     }
 127
 128     // Only print parens around the LHS if it is non-trivial.
 129     if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) {
 130       BE.getRHS()->print(OS, MAI);
 131     } else {
 132       OS << '(';
 133       BE.getRHS()->print(OS, MAI);
 134       OS << ')';
 135     }
 136     return;
 137   }
 138   }
 139
 140   llvm_unreachable("Invalid expression kind!");
 141 }
 142
 143 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 144 LLVM_DUMP_METHOD void MCExpr::dump() const {
 145   dbgs() << *this;
 146   dbgs() << '\n';
 147 }
 148 #endif
 149
 150 /* *** */
 151
 152 const MCBinaryExpr *MCBinaryExpr::create(Opcode Opc, const MCExpr *LHS,
 153                                          const MCExpr *RHS, MCContext &Ctx,
 154                                          SMLoc Loc) {
 155   return new (Ctx) MCBinaryExpr(Opc, LHS, RHS, Loc);
 156 }
 157
 158 const MCUnaryExpr *MCUnaryExpr::create(Opcode Opc, const MCExpr *Expr,
 159                                        MCContext &Ctx, SMLoc Loc) {
 160   return new (Ctx) MCUnaryExpr(Opc, Expr, Loc);
 161 }
 162
 163 const MCConstantExpr *MCConstantExpr::create(int64_t Value, MCContext &Ctx) {
 164   return new (Ctx) MCConstantExpr(Value);
 165 }
 166
 167 /* *** */
 168
 169 MCSymbolRefExpr::MCSymbolRefExpr(const MCSymbol *Symbol, VariantKind Kind,
 170                                  const MCAsmInfo *MAI, SMLoc Loc)
 171     : MCExpr(MCExpr::SymbolRef, Loc), Kind(Kind),
 172       UseParensForSymbolVariant(MAI->useParensForSymbolVariant()),
 173       HasSubsectionsViaSymbols(MAI->hasSubsectionsViaSymbols()),
 174       Symbol(Symbol) {
 175   assert(Symbol);
 176 }
 177
 178 const MCSymbolRefExpr *MCSymbolRefExpr::create(const MCSymbol *Sym,
 179                                                VariantKind Kind,
 180                                                MCContext &Ctx, SMLoc Loc) {
 181   return new (Ctx) MCSymbolRefExpr(Sym, Kind, Ctx.getAsmInfo(), Loc);
 182 }
 183
 184 const MCSymbolRefExpr *MCSymbolRefExpr::create(StringRef Name, VariantKind Kind,
 185                                                MCContext &Ctx) {
 186   return create(Ctx.getOrCreateSymbol(Name), Kind, Ctx);
 187 }
 188
 189 StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
 190   switch (Kind) {
 191   case VK_Invalid: return "<<invalid>>";
 192   case VK_None: return "<<none>>";
 193
 194   case VK_DTPOFF: return "DTPOFF";
 195   case VK_DTPREL: return "DTPREL";
 196   case VK_GOT: return "GOT";
 197   case VK_GOTOFF: return "GOTOFF";
 198   case VK_GOTREL: return "GOTREL";
 199   case VK_GOTPCREL: return "GOTPCREL";
 200   case VK_GOTTPOFF: return "GOTTPOFF";
 201   case VK_INDNTPOFF: return "INDNTPOFF";
 202   case VK_NTPOFF: return "NTPOFF";
 203   case VK_GOTNTPOFF: return "GOTNTPOFF";
 204   case VK_PLT: return "PLT";
 205   case VK_TLSGD: return "TLSGD";
 206   case VK_TLSLD: return "TLSLD";
 207   case VK_TLSLDM: return "TLSLDM";
 208   case VK_TPOFF: return "TPOFF";
 209   case VK_TPREL: return "TPREL";
 210   case VK_TLSCALL: return "tlscall";
 211   case VK_TLSDESC: return "tlsdesc";
 212   case VK_TLVP: return "TLVP";
 213   case VK_TLVPPAGE: return "TLVPPAGE";
 214   case VK_TLVPPAGEOFF: return "TLVPPAGEOFF";
 215   case VK_PAGE: return "PAGE";
 216   case VK_PAGEOFF: return "PAGEOFF";
 217   case VK_GOTPAGE: return "GOTPAGE";
 218   case VK_GOTPAGEOFF: return "GOTPAGEOFF";
 219   case VK_SECREL: return "SECREL32";
 220   case VK_SIZE: return "SIZE";
 221   case VK_WEAKREF: return "WEAKREF";
 222   case VK_X86_ABS8: return "ABS8";
 223   case VK_ARM_NONE: return "none";
 224   case VK_ARM_GOT_PREL: return "GOT_PREL";
 225   case VK_ARM_TARGET1: return "target1";
 226   case VK_ARM_TARGET2: return "target2";
 227   case VK_ARM_PREL31: return "prel31";
 228   case VK_ARM_SBREL: return "sbrel";
 229   case VK_ARM_TLSLDO: return "tlsldo";
 230   case VK_ARM_TLSDESCSEQ: return "tlsdescseq";
 231   case VK_AVR_NONE: return "none";
 232   case VK_AVR_LO8: return "lo8";
 233   case VK_AVR_HI8: return "hi8";
 234   case VK_AVR_HLO8: return "hlo8";
 235   case VK_AVR_DIFF8: return "diff8";
 236   case VK_AVR_DIFF16: return "diff16";
 237   case VK_AVR_DIFF32: return "diff32";
 238   case VK_PPC_LO: return "l";
 239   case VK_PPC_HI: return "h";
 240   case VK_PPC_HA: return "ha";
 241   case VK_PPC_HIGH: return "high";
 242   case VK_PPC_HIGHA: return "higha";
 243   case VK_PPC_HIGHER: return "higher";
 244   case VK_PPC_HIGHERA: return "highera";
 245   case VK_PPC_HIGHEST: return "highest";
 246   case VK_PPC_HIGHESTA: return "highesta";
 247   case VK_PPC_GOT_LO: return "got@l";
 248   case VK_PPC_GOT_HI: return "got@h";
 249   case VK_PPC_GOT_HA: return "got@ha";
 250   case VK_PPC_TOCBASE: return "tocbase";
 251   case VK_PPC_TOC: return "toc";
 252   case VK_PPC_TOC_LO: return "toc@l";
 253   case VK_PPC_TOC_HI: return "toc@h";
 254   case VK_PPC_TOC_HA: return "toc@ha";
 255   case VK_PPC_DTPMOD: return "dtpmod";
 256   case VK_PPC_TPREL_LO: return "tprel@l";
 257   case VK_PPC_TPREL_HI: return "tprel@h";
 258   case VK_PPC_TPREL_HA: return "tprel@ha";
 259   case VK_PPC_TPREL_HIGH: return "tprel@high";
 260   case VK_PPC_TPREL_HIGHA: return "tprel@higha";
 261   case VK_PPC_TPREL_HIGHER: return "tprel@higher";
 262   case VK_PPC_TPREL_HIGHERA: return "tprel@highera";
 263   case VK_PPC_TPREL_HIGHEST: return "tprel@highest";
 264   case VK_PPC_TPREL_HIGHESTA: return "tprel@highesta";
 265   case VK_PPC_DTPREL_LO: return "dtprel@l";
 266   case VK_PPC_DTPREL_HI: return "dtprel@h";
 267   case VK_PPC_DTPREL_HA: return "dtprel@ha";
 268   case VK_PPC_DTPREL_HIGH: return "dtprel@high";
 269   case VK_PPC_DTPREL_HIGHA: return "dtprel@higha";
 270   case VK_PPC_DTPREL_HIGHER: return "dtprel@higher";
 271   case VK_PPC_DTPREL_HIGHERA: return "dtprel@highera";
 272   case VK_PPC_DTPREL_HIGHEST: return "dtprel@highest";
 273   case VK_PPC_DTPREL_HIGHESTA: return "dtprel@highesta";
 274   case VK_PPC_GOT_TPREL: return "got@tprel";
 275   case VK_PPC_GOT_TPREL_LO: return "got@tprel@l";
 276   case VK_PPC_GOT_TPREL_HI: return "got@tprel@h";
 277   case VK_PPC_GOT_TPREL_HA: return "got@tprel@ha";
 278   case VK_PPC_GOT_DTPREL: return "got@dtprel";
 279   case VK_PPC_GOT_DTPREL_LO: return "got@dtprel@l";
 280   case VK_PPC_GOT_DTPREL_HI: return "got@dtprel@h";
 281   case VK_PPC_GOT_DTPREL_HA: return "got@dtprel@ha";
 282   case VK_PPC_TLS: return "tls";
 283   case VK_PPC_GOT_TLSGD: return "got@tlsgd";
 284   case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l";
 285   case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h";
 286   case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha";
 287   case VK_PPC_TLSGD: return "tlsgd";
 288   case VK_PPC_GOT_TLSLD: return "got@tlsld";
 289   case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l";
 290   case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h";
 291   case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha";
 292   case VK_PPC_TLSLD: return "tlsld";
 293   case VK_PPC_LOCAL: return "local";
 294   case VK_COFF_IMGREL32: return "IMGREL";
 295   case VK_Hexagon_PCREL: return "PCREL";
 296   case VK_Hexagon_LO16: return "LO16";
 297   case VK_Hexagon_HI16: return "HI16";
 298   case VK_Hexagon_GPREL: return "GPREL";
 299   case VK_Hexagon_GD_GOT: return "GDGOT";
 300   case VK_Hexagon_LD_GOT: return "LDGOT";
 301   case VK_Hexagon_GD_PLT: return "GDPLT";
 302   case VK_Hexagon_LD_PLT: return "LDPLT";
 303   case VK_Hexagon_IE: return "IE";
 304   case VK_Hexagon_IE_GOT: return "IEGOT";
 305   case VK_WebAssembly_FUNCTION: return "FUNCTION";
 306   case VK_WebAssembly_GLOBAL: return "GLOBAL";
 307   case VK_WebAssembly_TYPEINDEX: return "TYPEINDEX";
 308   case VK_WebAssembly_EVENT: return "EVENT";
 309   case VK_AMDGPU_GOTPCREL32_LO: return "gotpcrel32@lo";
 310   case VK_AMDGPU_GOTPCREL32_HI: return "gotpcrel32@hi";
 311   case VK_AMDGPU_REL32_LO: return "rel32@lo";
 312   case VK_AMDGPU_REL32_HI: return "rel32@hi";
 313   case VK_AMDGPU_REL64: return "rel64";
 314   }
 315   llvm_unreachable("Invalid variant kind");
 316 }
 317
 318 MCSymbolRefExpr::VariantKind
 319 MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
 320   return StringSwitch<VariantKind>(Name.lower())
 321     .Case("dtprel", VK_DTPREL)
 322     .Case("dtpoff", VK_DTPOFF)
 323     .Case("got", VK_GOT)
 324     .Case("gotoff", VK_GOTOFF)
 325     .Case("gotrel", VK_GOTREL)
 326     .Case("gotpcrel", VK_GOTPCREL)
 327     .Case("gottpoff", VK_GOTTPOFF)
 328     .Case("indntpoff", VK_INDNTPOFF)
 329     .Case("ntpoff", VK_NTPOFF)
 330     .Case("gotntpoff", VK_GOTNTPOFF)
 331     .Case("plt", VK_PLT)
 332     .Case("tlscall", VK_TLSCALL)
 333     .Case("tlsdesc", VK_TLSDESC)
 334     .Case("tlsgd", VK_TLSGD)
 335     .Case("tlsld", VK_TLSLD)
 336     .Case("tlsldm", VK_TLSLDM)
 337     .Case("tpoff", VK_TPOFF)
 338     .Case("tprel", VK_TPREL)
 339     .Case("tlvp", VK_TLVP)
 340     .Case("tlvppage", VK_TLVPPAGE)
 341     .Case("tlvppageoff", VK_TLVPPAGEOFF)
 342     .Case("page", VK_PAGE)
 343     .Case("pageoff", VK_PAGEOFF)
 344     .Case("gotpage", VK_GOTPAGE)
 345     .Case("gotpageoff", VK_GOTPAGEOFF)
 346     .Case("imgrel", VK_COFF_IMGREL32)
 347     .Case("secrel32", VK_SECREL)
 348     .Case("size", VK_SIZE)
 349     .Case("abs8", VK_X86_ABS8)
 350     .Case("l", VK_PPC_LO)
 351     .Case("h", VK_PPC_HI)
 352     .Case("ha", VK_PPC_HA)
 353     .Case("high", VK_PPC_HIGH)
 354     .Case("higha", VK_PPC_HIGHA)
 355     .Case("higher", VK_PPC_HIGHER)
 356     .Case("highera", VK_PPC_HIGHERA)
 357     .Case("highest", VK_PPC_HIGHEST)
 358     .Case("highesta", VK_PPC_HIGHESTA)
 359     .Case("got@l", VK_PPC_GOT_LO)
 360     .Case("got@h", VK_PPC_GOT_HI)
 361     .Case("got@ha", VK_PPC_GOT_HA)
 362     .Case("local", VK_PPC_LOCAL)
 363     .Case("tocbase", VK_PPC_TOCBASE)
 364     .Case("toc", VK_PPC_TOC)
 365     .Case("toc@l", VK_PPC_TOC_LO)
 366     .Case("toc@h", VK_PPC_TOC_HI)
 367     .Case("toc@ha", VK_PPC_TOC_HA)
 368     .Case("tls", VK_PPC_TLS)
 369     .Case("dtpmod", VK_PPC_DTPMOD)
 370     .Case("tprel@l", VK_PPC_TPREL_LO)
 371     .Case("tprel@h", VK_PPC_TPREL_HI)
 372     .Case("tprel@ha", VK_PPC_TPREL_HA)
 373     .Case("tprel@high", VK_PPC_TPREL_HIGH)
 374     .Case("tprel@higha", VK_PPC_TPREL_HIGHA)
 375     .Case("tprel@higher", VK_PPC_TPREL_HIGHER)
 376     .Case("tprel@highera", VK_PPC_TPREL_HIGHERA)
 377     .Case("tprel@highest", VK_PPC_TPREL_HIGHEST)
 378     .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA)
 379     .Case("dtprel@l", VK_PPC_DTPREL_LO)
 380     .Case("dtprel@h", VK_PPC_DTPREL_HI)
 381     .Case("dtprel@ha", VK_PPC_DTPREL_HA)
 382     .Case("dtprel@high", VK_PPC_DTPREL_HIGH)
 383     .Case("dtprel@higha", VK_PPC_DTPREL_HIGHA)
 384     .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER)
 385     .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA)
 386     .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST)
 387     .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA)
 388     .Case("got@tprel", VK_PPC_GOT_TPREL)
 389     .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO)
 390     .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI)
 391     .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA)
 392     .Case("got@dtprel", VK_PPC_GOT_DTPREL)
 393     .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO)
 394     .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI)
 395     .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA)
 396     .Case("got@tlsgd", VK_PPC_GOT_TLSGD)
 397     .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO)
 398     .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI)
 399     .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA)
 400     .Case("got@tlsld", VK_PPC_GOT_TLSLD)
 401     .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO)
 402     .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI)
 403     .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA)
 404     .Case("gdgot", VK_Hexagon_GD_GOT)
 405     .Case("gdplt", VK_Hexagon_GD_PLT)
 406     .Case("iegot", VK_Hexagon_IE_GOT)
 407     .Case("ie", VK_Hexagon_IE)
 408     .Case("ldgot", VK_Hexagon_LD_GOT)
 409     .Case("ldplt", VK_Hexagon_LD_PLT)
 410     .Case("pcrel", VK_Hexagon_PCREL)
 411     .Case("none", VK_ARM_NONE)
 412     .Case("got_prel", VK_ARM_GOT_PREL)
 413     .Case("target1", VK_ARM_TARGET1)
 414     .Case("target2", VK_ARM_TARGET2)
 415     .Case("prel31", VK_ARM_PREL31)
 416     .Case("sbrel", VK_ARM_SBREL)
 417     .Case("tlsldo", VK_ARM_TLSLDO)
 418     .Case("lo8", VK_AVR_LO8)
 419     .Case("hi8", VK_AVR_HI8)
 420     .Case("hlo8", VK_AVR_HLO8)
 421     .Case("function", VK_WebAssembly_FUNCTION)
 422     .Case("global", VK_WebAssembly_GLOBAL)
 423     .Case("typeindex", VK_WebAssembly_TYPEINDEX)
 424     .Case("event", VK_WebAssembly_EVENT)
 425     .Case("gotpcrel32@lo", VK_AMDGPU_GOTPCREL32_LO)
 426     .Case("gotpcrel32@hi", VK_AMDGPU_GOTPCREL32_HI)
 427     .Case("rel32@lo", VK_AMDGPU_REL32_LO)
 428     .Case("rel32@hi", VK_AMDGPU_REL32_HI)
 429     .Case("rel64", VK_AMDGPU_REL64)
 430     .Default(VK_Invalid);
 431 }
 432
 433 void MCSymbolRefExpr::printVariantKind(raw_ostream &OS) const {
 434   if (UseParensForSymbolVariant)
 435     OS << '(' << MCSymbolRefExpr::getVariantKindName(getKind()) << ')';
 436   else
 437     OS << '@' << MCSymbolRefExpr::getVariantKindName(getKind());
 438 }
 439
 440 /* *** */
 441
 442 void MCTargetExpr::anchor() {}
 443
 444 /* *** */
 445
 446 bool MCExpr::evaluateAsAbsolute(int64_t &Res) const {
 447   return evaluateAsAbsolute(Res, nullptr, nullptr, nullptr);
 448 }
 449
 450 bool MCExpr::evaluateAsAbsolute(int64_t &Res,
 451                                 const MCAsmLayout &Layout) const {
 452   return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr);
 453 }
 454
 455 bool MCExpr::evaluateAsAbsolute(int64_t &Res,
 456                                 const MCAsmLayout &Layout,
 457                                 const SectionAddrMap &Addrs) const {
 458   return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs);
 459 }
 460
 461 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {
 462   return evaluateAsAbsolute(Res, &Asm, nullptr, nullptr);
 463 }
 464
 465 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm) const {
 466   return evaluateAsAbsolute(Res, Asm, nullptr, nullptr);
 467 }
 468
 469 bool MCExpr::evaluateKnownAbsolute(int64_t &Res,
 470                                    const MCAsmLayout &Layout) const {
 471   return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr,
 472                             true);
 473 }
 474
 475 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
 476                                 const MCAsmLayout *Layout,
 477                                 const SectionAddrMap *Addrs) const {
 478   // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
 479   // absolutize differences across sections and that is what the MachO writer
 480   // uses Addrs for.
 481   return evaluateAsAbsolute(Res, Asm, Layout, Addrs, Addrs);
 482 }
 483
 484 bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
 485                                 const MCAsmLayout *Layout,
 486                                 const SectionAddrMap *Addrs, bool InSet) const {
 487   MCValue Value;
 488
 489   // Fast path constants.
 490   if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {
 491     Res = CE->getValue();
 492     return true;
 493   }
 494
 495   bool IsRelocatable =
 496       evaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs, InSet);
 497
 498   // Record the current value.
 499   Res = Value.getConstant();
 500
 501   return IsRelocatable && Value.isAbsolute();
 502 }
 503
 504 /// Helper method for \see EvaluateSymbolAdd().
 505 static void AttemptToFoldSymbolOffsetDifference(
 506     const MCAssembler *Asm, const MCAsmLayout *Layout,
 507     const SectionAddrMap *Addrs, bool InSet, const MCSymbolRefExpr *&A,
 508     const MCSymbolRefExpr *&B, int64_t &Addend) {
 509   if (!A || !B)
 510     return;
 511
 512   const MCSymbol &SA = A->getSymbol();
 513   const MCSymbol &SB = B->getSymbol();
 514
 515   if (SA.isUndefined() || SB.isUndefined())
 516     return;
 517
 518   if (!Asm->getWriter().isSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet))
 519     return;
 520
 521   if (SA.getFragment() == SB.getFragment() && !SA.isVariable() &&
 522       !SA.isUnset() && !SB.isVariable() && !SB.isUnset()) {
 523     Addend += (SA.getOffset() - SB.getOffset());
 524
 525     // Pointers to Thumb symbols need to have their low-bit set to allow
 526     // for interworking.
 527     if (Asm->isThumbFunc(&SA))
 528       Addend |= 1;
 529
 530     // If symbol is labeled as micromips, we set low-bit to ensure
 531     // correct offset in .gcc_except_table
 532     if (Asm->getBackend().isMicroMips(&SA))
 533       Addend |= 1;
 534
 535     // Clear the symbol expr pointers to indicate we have folded these
 536     // operands.
 537     A = B = nullptr;
 538     return;
 539   }
 540
 541   if (!Layout)
 542     return;
 543
 544   const MCSection &SecA = *SA.getFragment()->getParent();
 545   const MCSection &SecB = *SB.getFragment()->getParent();
 546
 547   if ((&SecA != &SecB) && !Addrs)
 548     return;
 549
 550   // Eagerly evaluate.
 551   Addend += Layout->getSymbolOffset(A->getSymbol()) -
 552             Layout->getSymbolOffset(B->getSymbol());
 553   if (Addrs && (&SecA != &SecB))
 554     Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB));
 555
 556   // Pointers to Thumb symbols need to have their low-bit set to allow
 557   // for interworking.
 558   if (Asm->isThumbFunc(&SA))
 559     Addend |= 1;
 560
 561   // If symbol is labeled as micromips, we set low-bit to ensure
 562   // correct offset in .gcc_except_table
 563   if (Asm->getBackend().isMicroMips(&SA))
 564     Addend |= 1;
 565
 566   // Clear the symbol expr pointers to indicate we have folded these
 567   // operands.
 568   A = B = nullptr;
 569 }
 570
 571 /// Evaluate the result of an add between (conceptually) two MCValues.
 572 ///
 573 /// This routine conceptually attempts to construct an MCValue:
 574 ///   Result = (Result_A - Result_B + Result_Cst)
 575 /// from two MCValue's LHS and RHS where
 576 ///   Result = LHS + RHS
 577 /// and
 578 ///   Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
 579 ///
 580 /// This routine attempts to aggresively fold the operands such that the result
 581 /// is representable in an MCValue, but may not always succeed.
 582 ///
 583 /// \returns True on success, false if the result is not representable in an
 584 /// MCValue.
 585
 586 /// NOTE: It is really important to have both the Asm and Layout arguments.
 587 /// They might look redundant, but this function can be used before layout
 588 /// is done (see the object streamer for example) and having the Asm argument
 589 /// lets us avoid relaxations early.
 590 static bool
 591 EvaluateSymbolicAdd(const MCAssembler *Asm, const MCAsmLayout *Layout,
 592                     const SectionAddrMap *Addrs, bool InSet, const MCValue &LHS,
 593                     const MCSymbolRefExpr *RHS_A, const MCSymbolRefExpr *RHS_B,
 594                     int64_t RHS_Cst, MCValue &Res) {
 595   // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy
 596   // about dealing with modifiers. This will ultimately bite us, one day.
 597   const MCSymbolRefExpr *LHS_A = LHS.getSymA();
 598   const MCSymbolRefExpr *LHS_B = LHS.getSymB();
 599   int64_t LHS_Cst = LHS.getConstant();
 600
 601   // Fold the result constant immediately.
 602   int64_t Result_Cst = LHS_Cst + RHS_Cst;
 603
 604   assert((!Layout || Asm) &&
 605          "Must have an assembler object if layout is given!");
 606
 607   // If we have a layout, we can fold resolved differences. Do not do this if
 608   // the backend requires this to be emitted as individual relocations, unless
 609   // the InSet flag is set to get the current difference anyway (used for
 610   // example to calculate symbol sizes).
 611   if (Asm &&
 612       (InSet || !Asm->getBackend().requiresDiffExpressionRelocations())) {
 613     // First, fold out any differences which are fully resolved. By
 614     // reassociating terms in
 615     //   Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
 616     // we have the four possible differences:
 617     //   (LHS_A - LHS_B),
 618     //   (LHS_A - RHS_B),
 619     //   (RHS_A - LHS_B),
 620     //   (RHS_A - RHS_B).
 621     // Since we are attempting to be as aggressive as possible about folding, we
 622     // attempt to evaluate each possible alternative.
 623     AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B,
 624                                         Result_Cst);
 625     AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B,
 626                                         Result_Cst);
 627     AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B,
 628                                         Result_Cst);
 629     AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B,
 630                                         Result_Cst);
 631   }
 632
 633   // We can't represent the addition or subtraction of two symbols.
 634   if ((LHS_A && RHS_A) || (LHS_B && RHS_B))
 635     return false;
 636
 637   // At this point, we have at most one additive symbol and one subtractive
 638   // symbol -- find them.
 639   const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;
 640   const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;
 641
 642   Res = MCValue::get(A, B, Result_Cst);
 643   return true;
 644 }
 645
 646 bool MCExpr::evaluateAsRelocatable(MCValue &Res,
 647                                    const MCAsmLayout *Layout,
 648                                    const MCFixup *Fixup) const {
 649   MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr;
 650   return evaluateAsRelocatableImpl(Res, Assembler, Layout, Fixup, nullptr,
 651                                    false);
 652 }
 653
 654 bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const {
 655   MCAssembler *Assembler = &Layout.getAssembler();
 656   return evaluateAsRelocatableImpl(Res, Assembler, &Layout, nullptr, nullptr,
 657                                    true);
 658 }
 659
 660 static bool canExpand(const MCSymbol &Sym, bool InSet) {
 661   const MCExpr *Expr = Sym.getVariableValue();
 662   const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr);
 663   if (Inner) {
 664     if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
 665       return false;
 666   }
 667
 668   if (InSet)
 669     return true;
 670   return !Sym.isInSection();
 671 }
 672
 673 bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
 674                                        const MCAsmLayout *Layout,
 675                                        const MCFixup *Fixup,
 676                                        const SectionAddrMap *Addrs,
 677                                        bool InSet) const {
 678   ++stats::MCExprEvaluate;
 679
 680   switch (getKind()) {
 681   case Target:
 682     return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Layout,
 683                                                                Fixup);
 684
 685   case Constant:
 686     Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
 687     return true;
 688
 689   case SymbolRef: {
 690     const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
 691     const MCSymbol &Sym = SRE->getSymbol();
 692
 693     // Evaluate recursively if this is a variable.
 694     if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None &&
 695         canExpand(Sym, InSet)) {
 696       bool IsMachO = SRE->hasSubsectionsViaSymbols();
 697       if (Sym.getVariableValue()->evaluateAsRelocatableImpl(
 698               Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO)) {
 699         if (!IsMachO)
 700           return true;
 701
 702         const MCSymbolRefExpr *A = Res.getSymA();
 703         const MCSymbolRefExpr *B = Res.getSymB();
 704         // FIXME: This is small hack. Given
 705         // a = b + 4
 706         // .long a
 707         // the OS X assembler will completely drop the 4. We should probably
 708         // include it in the relocation or produce an error if that is not
 709         // possible.
 710         // Allow constant expressions.
 711         if (!A && !B)
 712           return true;
 713         // Allows aliases with zero offset.
 714         if (Res.getConstant() == 0 && (!A || !B))
 715           return true;
 716       }
 717     }
 718
 719     Res = MCValue::get(SRE, nullptr, 0);
 720     return true;
 721   }
 722
 723   case Unary: {
 724     const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
 725     MCValue Value;
 726
 727     if (!AUE->getSubExpr()->evaluateAsRelocatableImpl(Value, Asm, Layout, Fixup,
 728                                                       Addrs, InSet))
 729       return false;
 730
 731     switch (AUE->getOpcode()) {
 732     case MCUnaryExpr::LNot:
 733       if (!Value.isAbsolute())
 734         return false;
 735       Res = MCValue::get(!Value.getConstant());
 736       break;
 737     case MCUnaryExpr::Minus:
 738       /// -(a - b + const) ==> (b - a - const)
 739       if (Value.getSymA() && !Value.getSymB())
 740         return false;
 741
 742       // The cast avoids undefined behavior if the constant is INT64_MIN.
 743       Res = MCValue::get(Value.getSymB(), Value.getSymA(),
 744                          -(uint64_t)Value.getConstant());
 745       break;
 746     case MCUnaryExpr::Not:
 747       if (!Value.isAbsolute())
 748         return false;
 749       Res = MCValue::get(~Value.getConstant());
 750       break;
 751     case MCUnaryExpr::Plus:
 752       Res = Value;
 753       break;
 754     }
 755
 756     return true;
 757   }
 758
 759   case Binary: {
 760     const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
 761     MCValue LHSValue, RHSValue;
 762
 763     if (!ABE->getLHS()->evaluateAsRelocatableImpl(LHSValue, Asm, Layout, Fixup,
 764                                                   Addrs, InSet) ||
 765         !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup,
 766                                                   Addrs, InSet)) {
 767       // Check if both are Target Expressions, see if we can compare them.
 768       if (const MCTargetExpr *L = dyn_cast<MCTargetExpr>(ABE->getLHS()))
 769         if (const MCTargetExpr *R = cast<MCTargetExpr>(ABE->getRHS())) {
 770           switch (ABE->getOpcode()) {
 771           case MCBinaryExpr::EQ:
 772             Res = MCValue::get((L->isEqualTo(R)) ? -1 : 0);
 773             return true;
 774           case MCBinaryExpr::NE:
 775             Res = MCValue::get((R->isEqualTo(R)) ? 0 : -1);
 776             return true;
 777           default: break;
 778           }
 779         }
 780       return false;
 781     }
 782
 783     // We only support a few operations on non-constant expressions, handle
 784     // those first.
 785     if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
 786       switch (ABE->getOpcode()) {
 787       default:
 788         return false;
 789       case MCBinaryExpr::Sub:
 790         // Negate RHS and add.
 791         // The cast avoids undefined behavior if the constant is INT64_MIN.
 792         return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
 793                                    RHSValue.getSymB(), RHSValue.getSymA(),
 794                                    -(uint64_t)RHSValue.getConstant(), Res);
 795
 796       case MCBinaryExpr::Add:
 797         return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
 798                                    RHSValue.getSymA(), RHSValue.getSymB(),
 799                                    RHSValue.getConstant(), Res);
 800       }
 801     }
 802
 803     // FIXME: We need target hooks for the evaluation. It may be limited in
 804     // width, and gas defines the result of comparisons differently from
 805     // Apple as.
 806     int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
 807     int64_t Result = 0;
 808     auto Op = ABE->getOpcode();
 809     switch (Op) {
 810     case MCBinaryExpr::AShr: Result = LHS >> RHS; break;
 811     case MCBinaryExpr::Add:  Result = LHS + RHS; break;
 812     case MCBinaryExpr::And:  Result = LHS & RHS; break;
 813     case MCBinaryExpr::Div:
 814     case MCBinaryExpr::Mod:
 815       // Handle division by zero. gas just emits a warning and keeps going,
 816       // we try to be stricter.
 817       // FIXME: Currently the caller of this function has no way to understand
 818       // we're bailing out because of 'division by zero'. Therefore, it will
 819       // emit a 'expected relocatable expression' error. It would be nice to
 820       // change this code to emit a better diagnostic.
 821       if (RHS == 0)
 822         return false;
 823       if (ABE->getOpcode() == MCBinaryExpr::Div)
 824         Result = LHS / RHS;
 825       else
 826         Result = LHS % RHS;
 827       break;
 828     case MCBinaryExpr::EQ:   Result = LHS == RHS; break;
 829     case MCBinaryExpr::GT:   Result = LHS > RHS; break;
 830     case MCBinaryExpr::GTE:  Result = LHS >= RHS; break;
 831     case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
 832     case MCBinaryExpr::LOr:  Result = LHS || RHS; break;
 833     case MCBinaryExpr::LShr: Result = uint64_t(LHS) >> uint64_t(RHS); break;
 834     case MCBinaryExpr::LT:   Result = LHS < RHS; break;
 835     case MCBinaryExpr::LTE:  Result = LHS <= RHS; break;
 836     case MCBinaryExpr::Mul:  Result = LHS * RHS; break;
 837     case MCBinaryExpr::NE:   Result = LHS != RHS; break;
 838     case MCBinaryExpr::Or:   Result = LHS | RHS; break;
 839     case MCBinaryExpr::Shl:  Result = uint64_t(LHS) << uint64_t(RHS); break;
 840     case MCBinaryExpr::Sub:  Result = LHS - RHS; break;
 841     case MCBinaryExpr::Xor:  Result = LHS ^ RHS; break;
 842     }
 843
 844     switch (Op) {
 845     default:
 846       Res = MCValue::get(Result);
 847       break;
 848     case MCBinaryExpr::EQ:
 849     case MCBinaryExpr::GT:
 850     case MCBinaryExpr::GTE:
 851     case MCBinaryExpr::LT:
 852     case MCBinaryExpr::LTE:
 853     case MCBinaryExpr::NE:
 854       // A comparison operator returns a -1 if true and 0 if false.
 855       Res = MCValue::get(Result ? -1 : 0);
 856       break;
 857     }
 858
 859     return true;
 860   }
 861   }
 862
 863   llvm_unreachable("Invalid assembly expression kind!");
 864 }
 865
 866 MCFragment *MCExpr::findAssociatedFragment() const {
 867   switch (getKind()) {
 868   case Target:
 869     // We never look through target specific expressions.
 870     return cast<MCTargetExpr>(this)->findAssociatedFragment();
 871
 872   case Constant:
 873     return MCSymbol::AbsolutePseudoFragment;
 874
 875   case SymbolRef: {
 876     const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
 877     const MCSymbol &Sym = SRE->getSymbol();
 878     return Sym.getFragment();
 879   }
 880
 881   case Unary:
 882     return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment();
 883
 884   case Binary: {
 885     const MCBinaryExpr *BE = cast<MCBinaryExpr>(this);
 886     MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment();
 887     MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment();
 888
 889     // If either is absolute, return the other.
 890     if (LHS_F == MCSymbol::AbsolutePseudoFragment)
 891       return RHS_F;
 892     if (RHS_F == MCSymbol::AbsolutePseudoFragment)
 893       return LHS_F;
 894
 895     // Not always correct, but probably the best we can do without more context.
 896     if (BE->getOpcode() == MCBinaryExpr::Sub)
 897       return MCSymbol::AbsolutePseudoFragment;
 898
 899     // Otherwise, return the first non-null fragment.
 900     return LHS_F ? LHS_F : RHS_F;
 901   }
 902   }
 903
 904   llvm_unreachable("Invalid assembly expression kind!");
 905 }