llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp

//===-- PPCELFObjectWriter.cpp - PPC ELF Writer ---------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "MCTargetDesc/PPCMCTargetDesc.h"
#include "MCTargetDesc/PPCFixupKinds.h"
#include "MCTargetDesc/PPCMCExpr.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/MC/MCELFObjectWriter.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/ErrorHandling.h"

using namespace llvm;

namespace {
  class PPCELFObjectWriter : public MCELFObjectTargetWriter {
  public:
    PPCELFObjectWriter(bool Is64Bit, uint8_t OSABI);

    virtual ~PPCELFObjectWriter();
  protected:
    virtual unsigned getRelocTypeInner(const MCValue &Target,
                                       const MCFixup &Fixup,
                                       bool IsPCRel) const;
    unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
                          bool IsPCRel, bool IsRelocWithSymbol) const override;
    virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
                                           const MCValue &Target,
                                           const MCFragment &F,
                                           const MCFixup &Fixup,
                                           bool IsPCRel) const;
    virtual const MCSymbol *undefinedExplicitRelSym(const MCValue &Target,
                                                    const MCFixup &Fixup,
                                                    bool IsPCRel) const;
  };
}

PPCELFObjectWriter::PPCELFObjectWriter(bool Is64Bit, uint8_t OSABI)
  : MCELFObjectTargetWriter(Is64Bit, OSABI,
                            Is64Bit ?  ELF::EM_PPC64 : ELF::EM_PPC,
                            /*HasRelocationAddend*/ true) {}

PPCELFObjectWriter::~PPCELFObjectWriter() {
}

static MCSymbolRefExpr::VariantKind getAccessVariant(const MCFixup &Fixup) {
  const MCExpr *Expr = Fixup.getValue();

  if (Expr->getKind() != MCExpr::Target)
    return Fixup.getAccessVariant();

  switch (cast<PPCMCExpr>(Expr)->getKind()) {
  case PPCMCExpr::VK_PPC_None:
    return MCSymbolRefExpr::VK_None;
  case PPCMCExpr::VK_PPC_LO:
    return MCSymbolRefExpr::VK_PPC_LO;
  case PPCMCExpr::VK_PPC_HI:
    return MCSymbolRefExpr::VK_PPC_HI;
  case PPCMCExpr::VK_PPC_HA:
    return MCSymbolRefExpr::VK_PPC_HA;
  case PPCMCExpr::VK_PPC_HIGHERA:
    return MCSymbolRefExpr::VK_PPC_HIGHERA;
  case PPCMCExpr::VK_PPC_HIGHER:
    return MCSymbolRefExpr::VK_PPC_HIGHER;
  case PPCMCExpr::VK_PPC_HIGHEST:
    return MCSymbolRefExpr::VK_PPC_HIGHEST;
  case PPCMCExpr::VK_PPC_HIGHESTA:
    return MCSymbolRefExpr::VK_PPC_HIGHESTA;
  }
  llvm_unreachable("unknown PPCMCExpr kind");
}

unsigned PPCELFObjectWriter::getRelocTypeInner(const MCValue &Target,
                                               const MCFixup &Fixup,
                                               bool IsPCRel) const
{
  MCSymbolRefExpr::VariantKind Modifier = getAccessVariant(Fixup);

  // determine the type of the relocation
  unsigned Type;
  if (IsPCRel) {
    switch ((unsigned)Fixup.getKind()) {
    default:
      llvm_unreachable("Unimplemented");
    case PPC::fixup_ppc_br24:
    case PPC::fixup_ppc_br24abs:
      Type = ELF::R_PPC_REL24;
      break;
    case PPC::fixup_ppc_brcond14:
    case PPC::fixup_ppc_brcond14abs:
      Type = ELF::R_PPC_REL14;
      break;
    case PPC::fixup_ppc_half16:
      switch (Modifier) {
      default: llvm_unreachable("Unsupported Modifier");
      case MCSymbolRefExpr::VK_None:
        Type = ELF::R_PPC_REL16;
        break;
      case MCSymbolRefExpr::VK_PPC_LO:
        Type = ELF::R_PPC_REL16_LO;
        break;
      case MCSymbolRefExpr::VK_PPC_HI:
        Type = ELF::R_PPC_REL16_HI;
        break;
      case MCSymbolRefExpr::VK_PPC_HA:
        Type = ELF::R_PPC_REL16_HA;
        break;
      }
      break;
    case FK_Data_4:
    case FK_PCRel_4:
      Type = ELF::R_PPC_REL32;
      break;
    case FK_Data_8:
    case FK_PCRel_8:
      Type = ELF::R_PPC64_REL64;
      break;
    }
  } else {
    switch ((unsigned)Fixup.getKind()) {
      default: llvm_unreachable("invalid fixup kind!");
    case PPC::fixup_ppc_br24abs:
      Type = ELF::R_PPC_ADDR24;
      break;
    case PPC::fixup_ppc_brcond14abs:
      Type = ELF::R_PPC_ADDR14; // XXX: or BRNTAKEN?_
      break;
    case PPC::fixup_ppc_half16:
      switch (Modifier) {
      default: llvm_unreachable("Unsupported Modifier");
      case MCSymbolRefExpr::VK_None:
        Type = ELF::R_PPC_ADDR16;
        break;
      case MCSymbolRefExpr::VK_PPC_LO:
        Type = ELF::R_PPC_ADDR16_LO;
        break;
      case MCSymbolRefExpr::VK_PPC_HI:
        Type = ELF::R_PPC_ADDR16_HI;
        break;
      case MCSymbolRefExpr::VK_PPC_HA:
        Type = ELF::R_PPC_ADDR16_HA;
        break;
      case MCSymbolRefExpr::VK_PPC_HIGHER:
        Type = ELF::R_PPC64_ADDR16_HIGHER;
        break;
      case MCSymbolRefExpr::VK_PPC_HIGHERA:
        Type = ELF::R_PPC64_ADDR16_HIGHERA;
        break;
      case MCSymbolRefExpr::VK_PPC_HIGHEST:
        Type = ELF::R_PPC64_ADDR16_HIGHEST;
        break;
      case MCSymbolRefExpr::VK_PPC_HIGHESTA:
        Type = ELF::R_PPC64_ADDR16_HIGHESTA;
        break;
      case MCSymbolRefExpr::VK_GOT:
        Type = ELF::R_PPC_GOT16;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_LO:
        Type = ELF::R_PPC_GOT16_LO;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_HI:
        Type = ELF::R_PPC_GOT16_HI;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_HA:
        Type = ELF::R_PPC_GOT16_HA;
        break;
      case MCSymbolRefExpr::VK_PPC_TOC:
        Type = ELF::R_PPC64_TOC16;
        break;
      case MCSymbolRefExpr::VK_PPC_TOC_LO:
        Type = ELF::R_PPC64_TOC16_LO;
        break;
      case MCSymbolRefExpr::VK_PPC_TOC_HI:
        Type = ELF::R_PPC64_TOC16_HI;
        break;
      case MCSymbolRefExpr::VK_PPC_TOC_HA:
        Type = ELF::R_PPC64_TOC16_HA;
        break;
      case MCSymbolRefExpr::VK_PPC_TPREL:
        Type = ELF::R_PPC_TPREL16;
        break;
      case MCSymbolRefExpr::VK_PPC_TPREL_LO:
        Type = ELF::R_PPC_TPREL16_LO;
        break;
      case MCSymbolRefExpr::VK_PPC_TPREL_HI:
        Type = ELF::R_PPC_TPREL16_HI;
        break;
      case MCSymbolRefExpr::VK_PPC_TPREL_HA:
        Type = ELF::R_PPC_TPREL16_HA;
        break;
      case MCSymbolRefExpr::VK_PPC_TPREL_HIGHER:
        Type = ELF::R_PPC64_TPREL16_HIGHER;
        break;
      case MCSymbolRefExpr::VK_PPC_TPREL_HIGHERA:
        Type = ELF::R_PPC64_TPREL16_HIGHERA;
        break;
      case MCSymbolRefExpr::VK_PPC_TPREL_HIGHEST:
        Type = ELF::R_PPC64_TPREL16_HIGHEST;
        break;
      case MCSymbolRefExpr::VK_PPC_TPREL_HIGHESTA:
        Type = ELF::R_PPC64_TPREL16_HIGHESTA;
        break;
      case MCSymbolRefExpr::VK_PPC_DTPREL:
        Type = ELF::R_PPC64_DTPREL16;
        break;
      case MCSymbolRefExpr::VK_PPC_DTPREL_LO:
        Type = ELF::R_PPC64_DTPREL16_LO;
        break;
      case MCSymbolRefExpr::VK_PPC_DTPREL_HI:
        Type = ELF::R_PPC64_DTPREL16_HI;
        break;
      case MCSymbolRefExpr::VK_PPC_DTPREL_HA:
        Type = ELF::R_PPC64_DTPREL16_HA;
        break;
      case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHER:
        Type = ELF::R_PPC64_DTPREL16_HIGHER;
        break;
      case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHERA:
        Type = ELF::R_PPC64_DTPREL16_HIGHERA;
        break;
      case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHEST:
        Type = ELF::R_PPC64_DTPREL16_HIGHEST;
        break;
      case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHESTA:
        Type = ELF::R_PPC64_DTPREL16_HIGHESTA;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TLSGD:
        Type = ELF::R_PPC64_GOT_TLSGD16;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_LO:
        Type = ELF::R_PPC64_GOT_TLSGD16_LO;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HI:
        Type = ELF::R_PPC64_GOT_TLSGD16_HI;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HA:
        Type = ELF::R_PPC64_GOT_TLSGD16_HA;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TLSLD:
        Type = ELF::R_PPC64_GOT_TLSLD16;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO:
        Type = ELF::R_PPC64_GOT_TLSLD16_LO;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HI:
        Type = ELF::R_PPC64_GOT_TLSLD16_HI;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HA:
        Type = ELF::R_PPC64_GOT_TLSLD16_HA;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TPREL:
        /* We don't have R_PPC64_GOT_TPREL16, but since GOT offsets
           are always 4-aligned, we can use R_PPC64_GOT_TPREL16_DS.  */
        Type = ELF::R_PPC64_GOT_TPREL16_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO:
        /* We don't have R_PPC64_GOT_TPREL16_LO, but since GOT offsets
           are always 4-aligned, we can use R_PPC64_GOT_TPREL16_LO_DS.  */
        Type = ELF::R_PPC64_GOT_TPREL16_LO_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HI:
        Type = ELF::R_PPC64_GOT_TPREL16_HI;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_DTPREL:
        /* We don't have R_PPC64_GOT_DTPREL16, but since GOT offsets
           are always 4-aligned, we can use R_PPC64_GOT_DTPREL16_DS.  */
        Type = ELF::R_PPC64_GOT_DTPREL16_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_LO:
        /* We don't have R_PPC64_GOT_DTPREL16_LO, but since GOT offsets
           are always 4-aligned, we can use R_PPC64_GOT_DTPREL16_LO_DS.  */
        Type = ELF::R_PPC64_GOT_DTPREL16_LO_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HA:
        Type = ELF::R_PPC64_GOT_TPREL16_HA;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HI:
        Type = ELF::R_PPC64_GOT_DTPREL16_HI;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HA:
        Type = ELF::R_PPC64_GOT_DTPREL16_HA;
        break;
      }
      break;
    case PPC::fixup_ppc_half16ds:
      switch (Modifier) {
      default: llvm_unreachable("Unsupported Modifier");
      case MCSymbolRefExpr::VK_None:
        Type = ELF::R_PPC64_ADDR16_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_LO:
        Type = ELF::R_PPC64_ADDR16_LO_DS;
        break;
      case MCSymbolRefExpr::VK_GOT:
        Type = ELF::R_PPC64_GOT16_DS;
	break;
      case MCSymbolRefExpr::VK_PPC_GOT_LO:
        Type = ELF::R_PPC64_GOT16_LO_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_TOC:
        Type = ELF::R_PPC64_TOC16_DS;
	break;
      case MCSymbolRefExpr::VK_PPC_TOC_LO:
        Type = ELF::R_PPC64_TOC16_LO_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_TPREL:
        Type = ELF::R_PPC64_TPREL16_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_TPREL_LO:
        Type = ELF::R_PPC64_TPREL16_LO_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_DTPREL:
        Type = ELF::R_PPC64_DTPREL16_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_DTPREL_LO:
        Type = ELF::R_PPC64_DTPREL16_LO_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TPREL:
        Type = ELF::R_PPC64_GOT_TPREL16_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO:
        Type = ELF::R_PPC64_GOT_TPREL16_LO_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_DTPREL:
        Type = ELF::R_PPC64_GOT_DTPREL16_DS;
        break;
      case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_LO:
        Type = ELF::R_PPC64_GOT_DTPREL16_LO_DS;
        break;
      }
      break;
    case PPC::fixup_ppc_nofixup:
      switch (Modifier) {
      default: llvm_unreachable("Unsupported Modifier");
      case MCSymbolRefExpr::VK_PPC_TLSGD:
        Type = ELF::R_PPC64_TLSGD;
        break;
      case MCSymbolRefExpr::VK_PPC_TLSLD:
        Type = ELF::R_PPC64_TLSLD;
        break;
      case MCSymbolRefExpr::VK_PPC_TLS:
        Type = ELF::R_PPC64_TLS;
        break;
      }
      break;
    case FK_Data_8:
      switch (Modifier) {
      default: llvm_unreachable("Unsupported Modifier");
      case MCSymbolRefExpr::VK_PPC_TOCBASE:
        Type = ELF::R_PPC64_TOC;
        break;
      case MCSymbolRefExpr::VK_None:
        Type = ELF::R_PPC64_ADDR64;
	break;
      case MCSymbolRefExpr::VK_PPC_DTPMOD:
        Type = ELF::R_PPC64_DTPMOD64;
	break;
      case MCSymbolRefExpr::VK_PPC_TPREL:
        Type = ELF::R_PPC64_TPREL64;
	break;
      case MCSymbolRefExpr::VK_PPC_DTPREL:
        Type = ELF::R_PPC64_DTPREL64;
	break;
      }
      break;
    case FK_Data_4:
      Type = ELF::R_PPC_ADDR32;
      break;
    case FK_Data_2:
      Type = ELF::R_PPC_ADDR16;
      break;
    }
  }
  return Type;
}

unsigned PPCELFObjectWriter::GetRelocType(const MCValue &Target,
                                          const MCFixup &Fixup,
                                          bool IsPCRel,
                                          bool IsRelocWithSymbol) const {
  return getRelocTypeInner(Target, Fixup, IsPCRel);
}

const MCSymbol *PPCELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm,
                                                   const MCValue &Target,
                                                   const MCFragment &F,
                                                   const MCFixup &Fixup,
                                                   bool IsPCRel) const {
  assert(Target.getSymA() && "SymA cannot be 0");
  MCSymbolRefExpr::VariantKind Modifier = Fixup.getAccessVariant();

  bool EmitThisSym;
  switch (Modifier) {
  // GOT references always need a relocation, even if the
  // target symbol is local.
  case MCSymbolRefExpr::VK_GOT:
  case MCSymbolRefExpr::VK_PPC_GOT_LO:
  case MCSymbolRefExpr::VK_PPC_GOT_HI:
  case MCSymbolRefExpr::VK_PPC_GOT_HA:
    EmitThisSym = true;
    break;
  default:
    EmitThisSym = false;
    break;
  } 

  if (EmitThisSym)
    return &Target.getSymA()->getSymbol().AliasedSymbol();
  return NULL;
}

const MCSymbol *PPCELFObjectWriter::undefinedExplicitRelSym(const MCValue &Target,
                                                            const MCFixup &Fixup,
                                                            bool IsPCRel) const {
  assert(Target.getSymA() && "SymA cannot be 0");
  const MCSymbol &Symbol = Target.getSymA()->getSymbol().AliasedSymbol();

  unsigned RelocType = getRelocTypeInner(Target, Fixup, IsPCRel);

  // The .odp creation emits a relocation against the symbol ".TOC." which
  // create a R_PPC64_TOC relocation. However the relocation symbol name
  // in final object creation should be NULL, since the symbol does not
  // really exist, it is just the reference to TOC base for the current
  // object file.
  bool EmitThisSym = RelocType != ELF::R_PPC64_TOC;

  if (EmitThisSym && !Symbol.isTemporary())
    return &Symbol;
  return NULL;
}

MCObjectWriter *llvm::createPPCELFObjectWriter(raw_ostream &OS,
                                               bool Is64Bit,
                                               bool IsLittleEndian,
                                               uint8_t OSABI) {
  MCELFObjectTargetWriter *MOTW = new PPCELFObjectWriter(Is64Bit, OSABI);
  return createELFObjectWriter(MOTW, OS, IsLittleEndian);
}