lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp

   1 //===-- MipsELFObjectWriter.cpp - Mips ELF Writer -------------------------===//
   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 #include "MCTargetDesc/MipsBaseInfo.h"
  11 #include "MCTargetDesc/MipsFixupKinds.h"
  12 #include "MCTargetDesc/MipsMCTargetDesc.h"
  13 #include "llvm/MC/MCAssembler.h"
  14 #include "llvm/MC/MCELFObjectWriter.h"
  15 #include "llvm/MC/MCExpr.h"
  16 #include "llvm/MC/MCSection.h"
  17 #include "llvm/MC/MCValue.h"
  18 #include "llvm/Support/ErrorHandling.h"
  19 #include <list>
  20
  21 using namespace llvm;
  22
  23 namespace {
  24   class MipsELFObjectWriter : public MCELFObjectTargetWriter {
  25   public:
  26     MipsELFObjectWriter(bool _is64Bit, uint8_t OSABI,
  27                         bool _isN64, bool IsLittleEndian);
  28
  29     virtual ~MipsELFObjectWriter();
  30
  31     unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
  32                           bool IsPCRel) const override;
  33     bool needsRelocateWithSymbol(const MCSymbolData &SD,
  34                                  unsigned Type) const override;
  35   };
  36 }
  37
  38 MipsELFObjectWriter::MipsELFObjectWriter(bool _is64Bit, uint8_t OSABI,
  39                                          bool _isN64, bool IsLittleEndian)
  40   : MCELFObjectTargetWriter(_is64Bit, OSABI, ELF::EM_MIPS,
  41                             /*HasRelocationAddend*/ (_isN64) ? true : false,
  42                             /*IsN64*/ _isN64) {}
  43
  44 MipsELFObjectWriter::~MipsELFObjectWriter() {}
  45
  46 unsigned MipsELFObjectWriter::GetRelocType(const MCValue &Target,
  47                                            const MCFixup &Fixup,
  48                                            bool IsPCRel) const {
  49   // determine the type of the relocation
  50   unsigned Type = (unsigned)ELF::R_MIPS_NONE;
  51   unsigned Kind = (unsigned)Fixup.getKind();
  52
  53   switch (Kind) {
  54   default:
  55     llvm_unreachable("invalid fixup kind!");
  56   case FK_Data_4:
  57     Type = ELF::R_MIPS_32;
  58     break;
  59   case FK_Data_8:
  60     Type = ELF::R_MIPS_64;
  61     break;
  62   case FK_GPRel_4:
  63     if (isN64()) {
  64       Type = setRType((unsigned)ELF::R_MIPS_GPREL32, Type);
  65       Type = setRType2((unsigned)ELF::R_MIPS_64, Type);
  66       Type = setRType3((unsigned)ELF::R_MIPS_NONE, Type);
  67     }
  68     else
  69       Type = ELF::R_MIPS_GPREL32;
  70     break;
  71   case Mips::fixup_Mips_GPREL16:
  72     Type = ELF::R_MIPS_GPREL16;
  73     break;
  74   case Mips::fixup_Mips_26:
  75     Type = ELF::R_MIPS_26;
  76     break;
  77   case Mips::fixup_Mips_CALL16:
  78     Type = ELF::R_MIPS_CALL16;
  79     break;
  80   case Mips::fixup_Mips_GOT_Global:
  81   case Mips::fixup_Mips_GOT_Local:
  82     Type = ELF::R_MIPS_GOT16;
  83     break;
  84   case Mips::fixup_Mips_HI16:
  85     Type = ELF::R_MIPS_HI16;
  86     break;
  87   case Mips::fixup_Mips_LO16:
  88     Type = ELF::R_MIPS_LO16;
  89     break;
  90   case Mips::fixup_Mips_TLSGD:
  91     Type = ELF::R_MIPS_TLS_GD;
  92     break;
  93   case Mips::fixup_Mips_GOTTPREL:
  94     Type = ELF::R_MIPS_TLS_GOTTPREL;
  95     break;
  96   case Mips::fixup_Mips_TPREL_HI:
  97     Type = ELF::R_MIPS_TLS_TPREL_HI16;
  98     break;
  99   case Mips::fixup_Mips_TPREL_LO:
 100     Type = ELF::R_MIPS_TLS_TPREL_LO16;
 101     break;
 102   case Mips::fixup_Mips_TLSLDM:
 103     Type = ELF::R_MIPS_TLS_LDM;
 104     break;
 105   case Mips::fixup_Mips_DTPREL_HI:
 106     Type = ELF::R_MIPS_TLS_DTPREL_HI16;
 107     break;
 108   case Mips::fixup_Mips_DTPREL_LO:
 109     Type = ELF::R_MIPS_TLS_DTPREL_LO16;
 110     break;
 111   case Mips::fixup_Mips_Branch_PCRel:
 112   case Mips::fixup_Mips_PC16:
 113     Type = ELF::R_MIPS_PC16;
 114     break;
 115   case Mips::fixup_Mips_GOT_PAGE:
 116     Type = ELF::R_MIPS_GOT_PAGE;
 117     break;
 118   case Mips::fixup_Mips_GOT_OFST:
 119     Type = ELF::R_MIPS_GOT_OFST;
 120     break;
 121   case Mips::fixup_Mips_GOT_DISP:
 122     Type = ELF::R_MIPS_GOT_DISP;
 123     break;
 124   case Mips::fixup_Mips_GPOFF_HI:
 125     Type = setRType((unsigned)ELF::R_MIPS_GPREL16, Type);
 126     Type = setRType2((unsigned)ELF::R_MIPS_SUB, Type);
 127     Type = setRType3((unsigned)ELF::R_MIPS_HI16, Type);
 128     break;
 129   case Mips::fixup_Mips_GPOFF_LO:
 130     Type = setRType((unsigned)ELF::R_MIPS_GPREL16, Type);
 131     Type = setRType2((unsigned)ELF::R_MIPS_SUB, Type);
 132     Type = setRType3((unsigned)ELF::R_MIPS_LO16, Type);
 133     break;
 134   case Mips::fixup_Mips_HIGHER:
 135     Type = ELF::R_MIPS_HIGHER;
 136     break;
 137   case Mips::fixup_Mips_HIGHEST:
 138     Type = ELF::R_MIPS_HIGHEST;
 139     break;
 140   case Mips::fixup_Mips_GOT_HI16:
 141     Type = ELF::R_MIPS_GOT_HI16;
 142     break;
 143   case Mips::fixup_Mips_GOT_LO16:
 144     Type = ELF::R_MIPS_GOT_LO16;
 145     break;
 146   case Mips::fixup_Mips_CALL_HI16:
 147     Type = ELF::R_MIPS_CALL_HI16;
 148     break;
 149   case Mips::fixup_Mips_CALL_LO16:
 150     Type = ELF::R_MIPS_CALL_LO16;
 151     break;
 152   case Mips::fixup_MICROMIPS_26_S1:
 153     Type = ELF::R_MICROMIPS_26_S1;
 154     break;
 155   case Mips::fixup_MICROMIPS_HI16:
 156     Type = ELF::R_MICROMIPS_HI16;
 157     break;
 158   case Mips::fixup_MICROMIPS_LO16:
 159     Type = ELF::R_MICROMIPS_LO16;
 160     break;
 161   case Mips::fixup_MICROMIPS_GOT16:
 162     Type = ELF::R_MICROMIPS_GOT16;
 163     break;
 164   case Mips::fixup_MICROMIPS_PC16_S1:
 165     Type = ELF::R_MICROMIPS_PC16_S1;
 166     break;
 167   case Mips::fixup_MICROMIPS_CALL16:
 168     Type = ELF::R_MICROMIPS_CALL16;
 169     break;
 170   case Mips::fixup_MICROMIPS_GOT_DISP:
 171     Type = ELF::R_MICROMIPS_GOT_DISP;
 172     break;
 173   case Mips::fixup_MICROMIPS_GOT_PAGE:
 174     Type = ELF::R_MICROMIPS_GOT_PAGE;
 175     break;
 176   case Mips::fixup_MICROMIPS_GOT_OFST:
 177     Type = ELF::R_MICROMIPS_GOT_OFST;
 178     break;
 179   case Mips::fixup_MICROMIPS_TLS_GD:
 180     Type = ELF::R_MICROMIPS_TLS_GD;
 181     break;
 182   case Mips::fixup_MICROMIPS_TLS_LDM:
 183     Type = ELF::R_MICROMIPS_TLS_LDM;
 184     break;
 185   case Mips::fixup_MICROMIPS_TLS_DTPREL_HI16:
 186     Type = ELF::R_MICROMIPS_TLS_DTPREL_HI16;
 187     break;
 188   case Mips::fixup_MICROMIPS_TLS_DTPREL_LO16:
 189     Type = ELF::R_MICROMIPS_TLS_DTPREL_LO16;
 190     break;
 191   case Mips::fixup_MICROMIPS_TLS_TPREL_HI16:
 192     Type = ELF::R_MICROMIPS_TLS_TPREL_HI16;
 193     break;
 194   case Mips::fixup_MICROMIPS_TLS_TPREL_LO16:
 195     Type = ELF::R_MICROMIPS_TLS_TPREL_LO16;
 196     break;
 197   case Mips::fixup_MIPS_PC19_S2:
 198     Type = ELF::R_MIPS_PC19_S2;
 199     break;
 200   case Mips::fixup_MIPS_PC18_S3:
 201     Type = ELF::R_MIPS_PC18_S3;
 202     break;
 203   case Mips::fixup_MIPS_PC21_S2:
 204     Type = ELF::R_MIPS_PC21_S2;
 205     break;
 206   case Mips::fixup_MIPS_PC26_S2:
 207     Type = ELF::R_MIPS_PC26_S2;
 208     break;
 209   case Mips::fixup_MIPS_PCHI16:
 210     Type = ELF::R_MIPS_PCHI16;
 211     break;
 212   case Mips::fixup_MIPS_PCLO16:
 213     Type = ELF::R_MIPS_PCLO16;
 214     break;
 215   }
 216   return Type;
 217 }
 218
 219 bool
 220 MipsELFObjectWriter::needsRelocateWithSymbol(const MCSymbolData &SD,
 221                                              unsigned Type) const {
 222   // FIXME: This is extremelly conservative. This really needs to use a
 223   // whitelist with a clear explanation for why each realocation needs to
 224   // point to the symbol, not to the section.
 225   switch (Type) {
 226   default:
 227     return true;
 228
 229   case ELF::R_MIPS_GOT16:
 230   case ELF::R_MIPS16_GOT16:
 231   case ELF::R_MICROMIPS_GOT16:
 232     llvm_unreachable("Should have been handled already");
 233
 234   // These relocations might be paired with another relocation. The pairing is
 235   // done by the static linker by matching the symbol. Since we only see one
 236   // relocation at a time, we have to force them to relocate with a symbol to
 237   // avoid ending up with a pair where one points to a section and another
 238   // points to a symbol.
 239   case ELF::R_MIPS_HI16:
 240   case ELF::R_MIPS16_HI16:
 241   case ELF::R_MICROMIPS_HI16:
 242   case ELF::R_MIPS_LO16:
 243   case ELF::R_MIPS16_LO16:
 244   case ELF::R_MICROMIPS_LO16:
 245     return true;
 246
 247   case ELF::R_MIPS_26:
 248   case ELF::R_MIPS_32:
 249   case ELF::R_MIPS_64:
 250   case ELF::R_MIPS_GPREL16:
 251     return false;
 252   }
 253 }
 254
 255 MCObjectWriter *llvm::createMipsELFObjectWriter(raw_ostream &OS,
 256                                                 uint8_t OSABI,
 257                                                 bool IsLittleEndian,
 258                                                 bool Is64Bit) {
 259   MCELFObjectTargetWriter *MOTW = new MipsELFObjectWriter(Is64Bit, OSABI,
 260                                                 (Is64Bit) ? true : false,
 261                                                 IsLittleEndian);
 262   return createELFObjectWriter(MOTW, OS, IsLittleEndian);
 263 }