//===- MCExpr.cpp - Assembly Level Expression Implementation --------------===//

//

//                     The LLVM Compiler Infrastructure

//

// This file is distributed under the University of Illinois Open Source

// License. See LICENSE.TXT for details.

//

//===----------------------------------------------------------------------===//

#include "llvm/MC/MCExpr.h"

#include "llvm/ADT/StringSwitch.h"

#include "llvm/MC/MCAsmInfo.h"

#include "llvm/MC/MCAsmLayout.h"

#include "llvm/MC/MCAssembler.h"

#include "llvm/MC/MCContext.h"

#include "llvm/MC/MCObjectWriter.h"

#include "llvm/MC/MCSymbol.h"

#include "llvm/MC/MCValue.h"

#include "llvm/Support/Debug.h"

#include "llvm/Support/ErrorHandling.h"

#include "llvm/Support/raw_ostream.h"

using namespace llvm_ks;

#define DEBUG_TYPE "mcexpr"

void MCExpr::print(raw_ostream &OS, const MCAsmInfo *MAI) const {

  switch (getKind()) {

  case MCExpr::Target:

    return cast<MCTargetExpr>(this)->printImpl(OS, MAI);

  case MCExpr::Constant:

    OS << cast<MCConstantExpr>(*this).getValue();

    return;

  case MCExpr::SymbolRef: {

    const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this);

    const MCSymbol &Sym = SRE.getSymbol();

    // Parenthesize names that start with $ so that they don't look like

    // absolute names.

    bool UseParens = Sym.getName().size() && Sym.getName()[0] == '$';

    if (UseParens) {

      OS << '(';

      Sym.print(OS, MAI);

      OS << ')';

    } else

      Sym.print(OS, MAI);

    if (SRE.getKind() != MCSymbolRefExpr::VK_None)

      SRE.printVariantKind(OS);

    return;

  }

  case MCExpr::Unary: {

    const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this);

    switch (UE.getOpcode()) {

    case MCUnaryExpr::LNot:  OS << '!'; break;

    case MCUnaryExpr::Minus: OS << '-'; break;

    case MCUnaryExpr::Not:   OS << '~'; break;

    case MCUnaryExpr::Plus:  OS << '+'; break;

    }

    UE.getSubExpr()->print(OS, MAI);

    return;

  }

  case MCExpr::Binary: {

    const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this);

    // Only print parens around the LHS if it is non-trivial.

    if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) {

      BE.getLHS()->print(OS, MAI);

    } else {

      OS << '(';

      BE.getLHS()->print(OS, MAI);

      OS << ')';

    }

    switch (BE.getOpcode()) {

    case MCBinaryExpr::Add:

      // Print "X-42" instead of "X+-42".

      if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) {

        if (RHSC->getValue() < 0) {

          OS << RHSC->getValue();

          return;

        }

      }

      OS <<  '+';

      break;

    case MCBinaryExpr::AShr: OS << ">>"; break;

    case MCBinaryExpr::And:  OS <<  '&'; break;

    case MCBinaryExpr::Div:  OS <<  '/'; break;

    case MCBinaryExpr::EQ:   OS << "=="; break;

    case MCBinaryExpr::GT:   OS <<  '>'; break;

    case MCBinaryExpr::GTE:  OS << ">="; break;

    case MCBinaryExpr::LAnd: OS << "&&"; break;

    case MCBinaryExpr::LOr:  OS << "||"; break;

    case MCBinaryExpr::LShr: OS << ">>"; break;

    case MCBinaryExpr::LT:   OS <<  '<'; break;

    case MCBinaryExpr::LTE:  OS << "<="; break;

    case MCBinaryExpr::Mod:  OS <<  '%'; break;

    case MCBinaryExpr::Mul:  OS <<  '*'; break;

    case MCBinaryExpr::NE:   OS << "!="; break;

    case MCBinaryExpr::Or:   OS <<  '|'; break;

    case MCBinaryExpr::Shl:  OS << "<<"; break;

    case MCBinaryExpr::Sub:  OS <<  '-'; break;

    case MCBinaryExpr::Xor:  OS <<  '^'; break;

    }

    // Only print parens around the LHS if it is non-trivial.

    if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) {

      BE.getRHS()->print(OS, MAI);

    } else {

      OS << '(';

      BE.getRHS()->print(OS, MAI);

      OS << ')';

    }

    return;

  }

  }

  llvm_unreachable("Invalid expression kind!");

}

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

LLVM_DUMP_METHOD void MCExpr::dump() const {

}

#endif

/* *** */

const MCBinaryExpr *MCBinaryExpr::create(Opcode Opc, const MCExpr *LHS,

                                         const MCExpr *RHS, MCContext &Ctx) {

  return new (Ctx) MCBinaryExpr(Opc, LHS, RHS);

}

const MCUnaryExpr *MCUnaryExpr::create(Opcode Opc, const MCExpr *Expr,

                                       MCContext &Ctx) {

  return new (Ctx) MCUnaryExpr(Opc, Expr);

}

const MCConstantExpr *MCConstantExpr::create(int64_t Value, MCContext &Ctx) {

  return new (Ctx) MCConstantExpr(Value);

}

/* *** */

MCSymbolRefExpr::MCSymbolRefExpr(const MCSymbol *Symbol, VariantKind Kind,

                                 const MCAsmInfo *MAI)

    : MCExpr(MCExpr::SymbolRef), Kind(Kind),

      UseParensForSymbolVariant(MAI->useParensForSymbolVariant()),

      HasSubsectionsViaSymbols(MAI->hasSubsectionsViaSymbols()),

      Symbol(Symbol) {

  assert(Symbol);

}

const MCSymbolRefExpr *MCSymbolRefExpr::create(const MCSymbol *Sym,

                                               VariantKind Kind,

                                               MCContext &Ctx) {

  return new (Ctx) MCSymbolRefExpr(Sym, Kind, Ctx.getAsmInfo());

}

const MCSymbolRefExpr *MCSymbolRefExpr::create(StringRef Name, VariantKind Kind,

                                               MCContext &Ctx) {

  return create(Ctx.getOrCreateSymbol(Name), Kind, Ctx);

}

StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {

  switch (Kind) {

  case VK_Invalid: return "<<invalid>>";

  case VK_None: return "<<none>>";

  case VK_GOT: return "GOT";

  case VK_GOTOFF: return "GOTOFF";

  case VK_GOTPCREL: return "GOTPCREL";

  case VK_GOTTPOFF: return "GOTTPOFF";

  case VK_INDNTPOFF: return "INDNTPOFF";

  case VK_NTPOFF: return "NTPOFF";

  case VK_GOTNTPOFF: return "GOTNTPOFF";

  case VK_PLT: return "PLT";

  case VK_TLSGD: return "TLSGD";

  case VK_TLSLD: return "TLSLD";

  case VK_TLSLDM: return "TLSLDM";

  case VK_TPOFF: return "TPOFF";

  case VK_DTPOFF: return "DTPOFF";

  case VK_TLVP: return "TLVP";

  case VK_TLVPPAGE: return "TLVPPAGE";

  case VK_TLVPPAGEOFF: return "TLVPPAGEOFF";

  case VK_PAGE: return "PAGE";

  case VK_PAGEOFF: return "PAGEOFF";

  case VK_GOTPAGE: return "GOTPAGE";

  case VK_GOTPAGEOFF: return "GOTPAGEOFF";

  case VK_SECREL: return "SECREL32";

  case VK_SIZE: return "SIZE";

  case VK_WEAKREF: return "WEAKREF";

  case VK_ARM_NONE: return "none";

  case VK_ARM_GOT_PREL: return "GOT_PREL";

  case VK_ARM_TARGET1: return "target1";

  case VK_ARM_TARGET2: return "target2";

  case VK_ARM_PREL31: return "prel31";

  case VK_ARM_SBREL: return "sbrel";

  case VK_ARM_TLSLDO: return "tlsldo";

  case VK_ARM_TLSCALL: return "tlscall";

  case VK_ARM_TLSDESC: return "tlsdesc";

  case VK_ARM_TLSDESCSEQ: return "tlsdescseq";

  case VK_PPC_LO: return "l";

  case VK_PPC_HI: return "h";

  case VK_PPC_HA: return "ha";

  case VK_PPC_HIGHER: return "higher";

  case VK_PPC_HIGHERA: return "highera";

  case VK_PPC_HIGHEST: return "highest";

  case VK_PPC_HIGHESTA: return "highesta";

  case VK_PPC_GOT_LO: return "got@l";

  case VK_PPC_GOT_HI: return "got@h";

  case VK_PPC_GOT_HA: return "got@ha";

  case VK_PPC_TOCBASE: return "tocbase";

  case VK_PPC_TOC: return "toc";

  case VK_PPC_TOC_LO: return "toc@l";

  case VK_PPC_TOC_HI: return "toc@h";

  case VK_PPC_TOC_HA: return "toc@ha";

  case VK_PPC_DTPMOD: return "dtpmod";

  case VK_PPC_TPREL: return "tprel";

  case VK_PPC_TPREL_LO: return "tprel@l";

  case VK_PPC_TPREL_HI: return "tprel@h";

  case VK_PPC_TPREL_HA: return "tprel@ha";

  case VK_PPC_TPREL_HIGHER: return "tprel@higher";

  case VK_PPC_TPREL_HIGHERA: return "tprel@highera";

  case VK_PPC_TPREL_HIGHEST: return "tprel@highest";

  case VK_PPC_TPREL_HIGHESTA: return "tprel@highesta";

  case VK_PPC_DTPREL: return "dtprel";

  case VK_PPC_DTPREL_LO: return "dtprel@l";

  case VK_PPC_DTPREL_HI: return "dtprel@h";

  case VK_PPC_DTPREL_HA: return "dtprel@ha";

  case VK_PPC_DTPREL_HIGHER: return "dtprel@higher";

  case VK_PPC_DTPREL_HIGHERA: return "dtprel@highera";

  case VK_PPC_DTPREL_HIGHEST: return "dtprel@highest";

  case VK_PPC_DTPREL_HIGHESTA: return "dtprel@highesta";

  case VK_PPC_GOT_TPREL: return "got@tprel";

  case VK_PPC_GOT_TPREL_LO: return "got@tprel@l";

  case VK_PPC_GOT_TPREL_HI: return "got@tprel@h";

  case VK_PPC_GOT_TPREL_HA: return "got@tprel@ha";

  case VK_PPC_GOT_DTPREL: return "got@dtprel";

  case VK_PPC_GOT_DTPREL_LO: return "got@dtprel@l";

  case VK_PPC_GOT_DTPREL_HI: return "got@dtprel@h";

  case VK_PPC_GOT_DTPREL_HA: return "got@dtprel@ha";

  case VK_PPC_TLS: return "tls";

  case VK_PPC_GOT_TLSGD: return "got@tlsgd";

  case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l";

  case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h";

  case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha";

  case VK_PPC_TLSGD: return "tlsgd";

  case VK_PPC_GOT_TLSLD: return "got@tlsld";

  case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l";

  case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h";

  case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha";

  case VK_PPC_TLSLD: return "tlsld";

  case VK_PPC_LOCAL: return "local";

  case VK_Mips_GPREL: return "GPREL";

  case VK_Mips_GOT_CALL: return "GOT_CALL";

  case VK_Mips_GOT16: return "GOT16";

  case VK_Mips_GOT: return "GOT";

  case VK_Mips_ABS_HI: return "ABS_HI";

  case VK_Mips_ABS_LO: return "ABS_LO";

  case VK_Mips_TLSGD: return "TLSGD";

  case VK_Mips_TLSLDM: return "TLSLDM";

  case VK_Mips_DTPREL_HI: return "DTPREL_HI";

  case VK_Mips_DTPREL_LO: return "DTPREL_LO";

  case VK_Mips_GOTTPREL: return "GOTTPREL";

  case VK_Mips_TPREL_HI: return "TPREL_HI";

  case VK_Mips_TPREL_LO: return "TPREL_LO";

  case VK_Mips_GPOFF_HI: return "GPOFF_HI";

  case VK_Mips_GPOFF_LO: return "GPOFF_LO";

  case VK_Mips_GOT_DISP: return "GOT_DISP";

  case VK_Mips_GOT_PAGE: return "GOT_PAGE";

  case VK_Mips_GOT_OFST: return "GOT_OFST";

  case VK_Mips_HIGHER:   return "HIGHER";

  case VK_Mips_HIGHEST:  return "HIGHEST";

  case VK_Mips_GOT_HI16: return "GOT_HI16";

  case VK_Mips_GOT_LO16: return "GOT_LO16";

  case VK_Mips_CALL_HI16: return "CALL_HI16";

  case VK_Mips_CALL_LO16: return "CALL_LO16";

  case VK_Mips_PCREL_HI16: return "PCREL_HI16";

  case VK_Mips_PCREL_LO16: return "PCREL_LO16";

  case VK_COFF_IMGREL32: return "IMGREL";

  case VK_Hexagon_PCREL: return "PCREL";

  case VK_Hexagon_LO16: return "LO16";

  case VK_Hexagon_HI16: return "HI16";

  case VK_Hexagon_GPREL: return "GPREL";

  case VK_Hexagon_GD_GOT: return "GDGOT";

  case VK_Hexagon_LD_GOT: return "LDGOT";

  case VK_Hexagon_GD_PLT: return "GDPLT";

  case VK_Hexagon_LD_PLT: return "LDPLT";

  case VK_Hexagon_IE: return "IE";

  case VK_Hexagon_IE_GOT: return "IEGOT";

  case VK_WebAssembly_FUNCTION: return "FUNCTION";

  case VK_TPREL: return "tprel";

  case VK_DTPREL: return "dtprel";

  }

  llvm_unreachable("Invalid variant kind");

}

MCSymbolRefExpr::VariantKind

MCSymbolRefExpr::getVariantKindForName(StringRef Name) {

  return StringSwitch<VariantKind>(Name.lower())

    .Case("got", VK_GOT)

    .Case("gotoff", VK_GOTOFF)

    .Case("gotpcrel", VK_GOTPCREL)

    .Case("gottpoff", VK_GOTTPOFF)

    .Case("indntpoff", VK_INDNTPOFF)

    .Case("ntpoff", VK_NTPOFF)

    .Case("gotntpoff", VK_GOTNTPOFF)

    .Case("plt", VK_PLT)

    .Case("tlsgd", VK_TLSGD)

    .Case("tlsld", VK_TLSLD)

    .Case("tlsldm", VK_TLSLDM)

    .Case("tpoff", VK_TPOFF)

    .Case("dtpoff", VK_DTPOFF)

    .Case("tlvp", VK_TLVP)

    .Case("tlvppage", VK_TLVPPAGE)

    .Case("tlvppageoff", VK_TLVPPAGEOFF)

    .Case("page", VK_PAGE)

    .Case("pageoff", VK_PAGEOFF)

    .Case("gotpage", VK_GOTPAGE)

    .Case("gotpageoff", VK_GOTPAGEOFF)

    .Case("imgrel", VK_COFF_IMGREL32)

    .Case("secrel32", VK_SECREL)

    .Case("size", VK_SIZE)

    .Case("l", VK_PPC_LO)

    .Case("h", VK_PPC_HI)

    .Case("ha", VK_PPC_HA)

    .Case("higher", VK_PPC_HIGHER)

    .Case("highera", VK_PPC_HIGHERA)

    .Case("highest", VK_PPC_HIGHEST)

    .Case("highesta", VK_PPC_HIGHESTA)

    .Case("got@l", VK_PPC_GOT_LO)

    .Case("got@h", VK_PPC_GOT_HI)

    .Case("got@ha", VK_PPC_GOT_HA)

    .Case("local", VK_PPC_LOCAL)

    .Case("tocbase", VK_PPC_TOCBASE)

    .Case("toc", VK_PPC_TOC)

    .Case("toc@l", VK_PPC_TOC_LO)

    .Case("toc@h", VK_PPC_TOC_HI)

    .Case("toc@ha", VK_PPC_TOC_HA)

    .Case("tls", VK_PPC_TLS)

    .Case("dtpmod", VK_PPC_DTPMOD)

    .Case("tprel", VK_PPC_TPREL)

    .Case("tprel@l", VK_PPC_TPREL_LO)

    .Case("tprel@h", VK_PPC_TPREL_HI)

    .Case("tprel@ha", VK_PPC_TPREL_HA)

    .Case("tprel@higher", VK_PPC_TPREL_HIGHER)

    .Case("tprel@highera", VK_PPC_TPREL_HIGHERA)

    .Case("tprel@highest", VK_PPC_TPREL_HIGHEST)

    .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA)

    .Case("dtprel", VK_PPC_DTPREL)

    .Case("dtprel@l", VK_PPC_DTPREL_LO)

    .Case("dtprel@h", VK_PPC_DTPREL_HI)

    .Case("dtprel@ha", VK_PPC_DTPREL_HA)

    .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER)

    .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA)

    .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST)

    .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA)

    .Case("got@tprel", VK_PPC_GOT_TPREL)

    .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO)

    .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI)

    .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA)

    .Case("got@dtprel", VK_PPC_GOT_DTPREL)

    .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO)

    .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI)

    .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA)

    .Case("got@tlsgd", VK_PPC_GOT_TLSGD)

    .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO)

    .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI)

    .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA)

    .Case("got@tlsld", VK_PPC_GOT_TLSLD)

    .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO)

    .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI)

    .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA)

    .Case("gdgot", VK_Hexagon_GD_GOT)

    .Case("gdplt", VK_Hexagon_GD_PLT)

    .Case("iegot", VK_Hexagon_IE_GOT)

    .Case("ie", VK_Hexagon_IE)

    .Case("ldgot", VK_Hexagon_LD_GOT)

    .Case("ldplt", VK_Hexagon_LD_PLT)

    .Case("pcrel", VK_Hexagon_PCREL)

    .Case("none", VK_ARM_NONE)

    .Case("got_prel", VK_ARM_GOT_PREL)

    .Case("target1", VK_ARM_TARGET1)

    .Case("target2", VK_ARM_TARGET2)

    .Case("prel31", VK_ARM_PREL31)

    .Case("sbrel", VK_ARM_SBREL)

    .Case("tlsldo", VK_ARM_TLSLDO)

    .Case("tlscall", VK_ARM_TLSCALL)

    .Case("tlsdesc", VK_ARM_TLSDESC)

    .Default(VK_Invalid);

}

void MCSymbolRefExpr::printVariantKind(raw_ostream &OS) const {

  if (UseParensForSymbolVariant)

    OS << '(' << MCSymbolRefExpr::getVariantKindName(getKind()) << ')';

  else

    OS << '@' << MCSymbolRefExpr::getVariantKindName(getKind());

}

/* *** */

bool MCExpr::evaluateAsAbsolute(int64_t &Res) const {

  return evaluateAsAbsolute(Res, nullptr, nullptr, nullptr);

}

bool MCExpr::evaluateAsAbsolute(int64_t &Res,

                                const MCAsmLayout &Layout) const {

  return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr);

}

bool MCExpr::evaluateAsAbsolute(int64_t &Res,

                                const MCAsmLayout &Layout,

                                const SectionAddrMap &Addrs) const {

  return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs);

}

bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {

  return evaluateAsAbsolute(Res, &Asm, nullptr, nullptr);

}

bool MCExpr::evaluateKnownAbsolute(int64_t &Res,

                                   const MCAsmLayout &Layout) const {

  return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr,

                            true);

}

bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,

                                const MCAsmLayout *Layout,

                                const SectionAddrMap *Addrs) const {

  // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us

  // absolutize differences across sections and that is what the MachO writer

  // uses Addrs for.

  return evaluateAsAbsolute(Res, Asm, Layout, Addrs, Addrs);

}

bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,

                                const MCAsmLayout *Layout,

                                const SectionAddrMap *Addrs, bool InSet) const

{

  MCValue Value;

  // Fast path constants.

  if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {

    Res = CE->getValue();

    return true;

  }

  bool valid;

  bool IsRelocatable =

      evaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs, InSet, valid);

  // Record the current value.

  Res = Value.getConstant();

  return IsRelocatable && Value.isAbsolute();

}

/// \brief Helper method for \see EvaluateSymbolAdd().

static void AttemptToFoldSymbolOffsetDifference(

    const MCAssembler *Asm, const MCAsmLayout *Layout,

    const SectionAddrMap *Addrs, bool InSet, const MCSymbolRefExpr *&A,

    const MCSymbolRefExpr *&B, int64_t &Addend, bool &valid) {

  valid = true;

  if (!A || !B)

    return;

  const MCSymbol &SA = A->getSymbol();

  const MCSymbol &SB = B->getSymbol();

  if (SA.isUndefined() || SB.isUndefined())

    return;

  if (!Asm->getWriter().isSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet, valid))

    return;

  if (!valid)

      return;

  if (SA.getFragment() == SB.getFragment() && !SA.isVariable() &&

      !SB.isVariable()) {

    Addend += (SA.getOffset() - SB.getOffset());

    // Pointers to Thumb symbols need to have their low-bit set to allow

    // for interworking.

    if (Asm->isThumbFunc(&SA))

      Addend |= 1;

    // Clear the symbol expr pointers to indicate we have folded these

    // operands.

    A = B = nullptr;

    return;

  }

  if (!Layout)

    return;

  const MCSection &SecA = *SA.getFragment()->getParent();

  const MCSection &SecB = *SB.getFragment()->getParent();

  if ((&SecA != &SecB) && !Addrs)

    return;

  // Eagerly evaluate.

  bool valid1, valid2;

  Addend += Layout->getSymbolOffset(A->getSymbol(), valid1) -

            Layout->getSymbolOffset(B->getSymbol(), valid2);

  if (Addrs && (&SecA != &SecB))

    Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB));

  // Pointers to Thumb symbols need to have their low-bit set to allow

  // for interworking.

  if (Asm->isThumbFunc(&SA))

    Addend |= 1;

  // Clear the symbol expr pointers to indicate we have folded these

  // operands.

  A = B = nullptr;

}

/// \brief Evaluate the result of an add between (conceptually) two MCValues.

///

/// This routine conceptually attempts to construct an MCValue:

///   Result = (Result_A - Result_B + Result_Cst)

/// from two MCValue's LHS and RHS where

///   Result = LHS + RHS

/// and

///   Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).

///

/// This routine attempts to aggresively fold the operands such that the result

/// is representable in an MCValue, but may not always succeed.

///

/// \returns True on success, false if the result is not representable in an

/// MCValue.

/// NOTE: It is really important to have both the Asm and Layout arguments.

/// They might look redundant, but this function can be used before layout

/// is done (see the object streamer for example) and having the Asm argument

/// lets us avoid relaxations early.

static bool

EvaluateSymbolicAdd(const MCAssembler *Asm, const MCAsmLayout *Layout,

                    const SectionAddrMap *Addrs, bool InSet, const MCValue &LHS,

                    const MCSymbolRefExpr *RHS_A, const MCSymbolRefExpr *RHS_B,

                    int64_t RHS_Cst, MCValue &Res, bool &valid)

{

  // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy

  // about dealing with modifiers. This will ultimately bite us, one day.

  const MCSymbolRefExpr *LHS_A = LHS.getSymA();

  const MCSymbolRefExpr *LHS_B = LHS.getSymB();

  int64_t LHS_Cst = LHS.getConstant();

  // Fold the result constant immediately.

  int64_t Result_Cst = LHS_Cst + RHS_Cst;

  assert((!Layout || Asm) &&

         "Must have an assembler object if layout is given!");

  // If we have a layout, we can fold resolved differences.

  if (Asm) {

    // First, fold out any differences which are fully resolved. By

    // reassociating terms in

    //   Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).

    // we have the four possible differences:

    //   (LHS_A - LHS_B),

    //   (LHS_A - RHS_B),

    //   (RHS_A - LHS_B),

    //   (RHS_A - RHS_B).

    // Since we are attempting to be as aggressive as possible about folding, we

    // attempt to evaluate each possible alternative.

    AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B,

                                        Result_Cst, valid);

    if (!valid)

        return false;

    AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B,

                                        Result_Cst, valid);

    if (!valid)

        return false;

    AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B,

                                        Result_Cst, valid);

    if (!valid)

        return false;

    AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B,

                                        Result_Cst, valid);

    if (!valid)

        return false;

  }

  // We can't represent the addition or subtraction of two symbols.

  if ((LHS_A && RHS_A) || (LHS_B && RHS_B))

    return false;

  // At this point, we have at most one additive symbol and one subtractive

  // symbol -- find them.

  const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;

  const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;

  Res = MCValue::get(A, B, Result_Cst);

  return true;

}

bool MCExpr::evaluateAsRelocatable(MCValue &Res,

                                   const MCAsmLayout *Layout,

                                   const MCFixup *Fixup) const

{

  MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr;

  bool valid;

  return evaluateAsRelocatableImpl(Res, Assembler, Layout, Fixup, nullptr,

                                   false, valid);

}

bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const

{

  MCAssembler *Assembler = &Layout.getAssembler();

  bool valid;

  return evaluateAsRelocatableImpl(Res, Assembler, &Layout, nullptr, nullptr,

                                   true, valid);

}

static bool canExpand(const MCSymbol &Sym, bool InSet) {

  const MCExpr *Expr = Sym.getVariableValue();

  const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr);

  if (Inner) {

    if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)

      return false;

  }

  if (InSet)

    return true;

  return !Sym.isInSection();

}

bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,

                                       const MCAsmLayout *Layout,

                                       const MCFixup *Fixup,

                                       const SectionAddrMap *Addrs,

                                       bool InSet, bool &valid) const

{

  switch (getKind()) {

  case Target:

    return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Layout,

                                                               Fixup);

  case Constant:

    Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());

    return true;

  case SymbolRef: {

    const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);

    const MCSymbol &Sym = SRE->getSymbol();

    // Evaluate recursively if this is a variable.

    if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None &&

        canExpand(Sym, InSet)) {

      bool IsMachO = SRE->hasSubsectionsViaSymbols();

      bool valid;

      if (Sym.getVariableValue()->evaluateAsRelocatableImpl(

              Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO, valid)) {

        if (!IsMachO)

          return true;

        const MCSymbolRefExpr *A = Res.getSymA();

        const MCSymbolRefExpr *B = Res.getSymB();

        // FIXME: This is small hack. Given

        // a = b + 4

        // .long a

        // the OS X assembler will completely drop the 4. We should probably

        // include it in the relocation or produce an error if that is not

        // possible.

        if (!A && !B)

          return true;

      }

    }

    Res = MCValue::get(SRE, nullptr, 0);

    return true;

  }

  case Unary: {

    const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);

    MCValue Value;

    bool valid;

    if (!AUE->getSubExpr()->evaluateAsRelocatableImpl(Value, Asm, Layout, Fixup,

                                                      Addrs, InSet, valid))

      return false;

    switch (AUE->getOpcode()) {

    case MCUnaryExpr::LNot:

      if (!Value.isAbsolute())

        return false;

      Res = MCValue::get(!Value.getConstant());

      break;

    case MCUnaryExpr::Minus:

      /// -(a - b + const) ==> (b - a - const)

      if (Value.getSymA() && !Value.getSymB())

        return false;

      Res = MCValue::get(Value.getSymB(), Value.getSymA(),

                         -Value.getConstant());

      break;

    case MCUnaryExpr::Not:

      if (!Value.isAbsolute())

        return false;

      Res = MCValue::get(~Value.getConstant());

      break;

    case MCUnaryExpr::Plus:

      Res = Value;

      break;

    }

    return true;

  }

  case Binary: {

    const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);

    MCValue LHSValue, RHSValue;

    bool valid;

    if (!ABE->getLHS()->evaluateAsRelocatableImpl(LHSValue, Asm, Layout, Fixup,

                                                  Addrs, InSet, valid) ||

        !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup,

                                                  Addrs, InSet, valid))

      return false;

    // We only support a few operations on non-constant expressions, handle

    // those first.

    if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {

      switch (ABE->getOpcode()) {

      default:

        return false;

      case MCBinaryExpr::Sub:

        // Negate RHS and add.

        return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,

                                   RHSValue.getSymB(), RHSValue.getSymA(),

                                   -RHSValue.getConstant(), Res, valid);

      case MCBinaryExpr::Add:

        return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,

                                   RHSValue.getSymA(), RHSValue.getSymB(),

                                   RHSValue.getConstant(), Res, valid);

      }

    }

    // FIXME: We need target hooks for the evaluation. It may be limited in

    // width, and gas defines the result of comparisons differently from

    // Apple as.

    int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();

    int64_t Result = 0;

    switch (ABE->getOpcode()) {

    case MCBinaryExpr::AShr: Result = LHS >> RHS; break;

    case MCBinaryExpr::Add:  Result = LHS + RHS; break;

    case MCBinaryExpr::And:  Result = LHS & RHS; break;

    case MCBinaryExpr::Div:

      // Handle division by zero. gas just emits a warning and keeps going,

      // we try to be stricter.

      // FIXME: Currently the caller of this function has no way to understand

      // we're bailing out because of 'division by zero'. Therefore, it will

      // emit a 'expected relocatable expression' error. It would be nice to

      // change this code to emit a better diagnostic.

      if (RHS == 0)

        return false;

      Result = LHS / RHS;

      break;

    case MCBinaryExpr::EQ:   Result = LHS == RHS; break;

    case MCBinaryExpr::GT:   Result = LHS > RHS; break;

    case MCBinaryExpr::GTE:  Result = LHS >= RHS; break;

    case MCBinaryExpr::LAnd: Result = LHS && RHS; break;

    case MCBinaryExpr::LOr:  Result = LHS || RHS; break;

    case MCBinaryExpr::LShr: Result = uint64_t(LHS) >> uint64_t(RHS); break;

    case MCBinaryExpr::LT:   Result = LHS < RHS; break;

    case MCBinaryExpr::LTE:  Result = LHS <= RHS; break;

    case MCBinaryExpr::Mod:

      // Handle division by zero. gas just emits a warning and keeps going,

      // we try to be stricter.

      // FIXME: Currently the caller of this function has no way to understand

      // we're bailing out because of 'division by zero'. Therefore, it will

      // emit a 'expected relocatable expression' error. It would be nice to

      // change this code to emit a better diagnostic.

      if (RHS == 0)

        return false;

      Result = LHS % RHS;

      break;

    case MCBinaryExpr::Mul:  Result = LHS * RHS; break;

    case MCBinaryExpr::NE:   Result = LHS != RHS; break;

    case MCBinaryExpr::Or:   Result = LHS | RHS; break;

    case MCBinaryExpr::Shl:  Result = uint64_t(LHS) << uint64_t(RHS); break;

    case MCBinaryExpr::Sub:  Result = LHS - RHS; break;

    case MCBinaryExpr::Xor:  Result = LHS ^ RHS; break;

    }

    Res = MCValue::get(Result);

    return true;

  }

  }

  llvm_unreachable("Invalid assembly expression kind!");

}

MCFragment *MCExpr::findAssociatedFragment() const {

  switch (getKind()) {

  case Target:

    // We never look through target specific expressions.

    return cast<MCTargetExpr>(this)->findAssociatedFragment();

  case Constant:

    return MCSymbol::AbsolutePseudoFragment;

  case SymbolRef: {

    const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);

    const MCSymbol &Sym = SRE->getSymbol();

    return Sym.getFragment();

  }

  case Unary:

    return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment();

  case Binary: {

    const MCBinaryExpr *BE = cast<MCBinaryExpr>(this);

    MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment();

    MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment();

    // If either is absolute, return the other.

    if (LHS_F == MCSymbol::AbsolutePseudoFragment)

      return RHS_F;

    if (RHS_F == MCSymbol::AbsolutePseudoFragment)

      return LHS_F;

    // Not always correct, but probably the best we can do without more context.

    if (BE->getOpcode() == MCBinaryExpr::Sub)

      return MCSymbol::AbsolutePseudoFragment;

    // Otherwise, return the first non-null fragment.

    return LHS_F ? LHS_F : RHS_F;

  }

  }

  llvm_unreachable("Invalid assembly expression kind!");

}