contrib/llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp

   1 //===-- ARMELFObjectWriter.cpp - ARM 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/ARMMCTargetDesc.h"
  11 #include "MCTargetDesc/ARMFixupKinds.h"
  12 #include "llvm/ADT/Statistic.h"
  13 #include "llvm/ADT/StringSwitch.h"
  14 #include "llvm/MC/MCELFObjectWriter.h"
  15 #include "llvm/MC/MCExpr.h"
  16 #include "llvm/MC/MCSectionELF.h"
  17 #include "llvm/MC/MCValue.h"
  18 #include "llvm/Support/Debug.h"
  19 #include "llvm/Support/ErrorHandling.h"
  20 #include "llvm/Support/raw_ostream.h"
  21
  22 using namespace llvm;
  23
  24 namespace {
  25   class ARMELFObjectWriter : public MCELFObjectTargetWriter {
  26     enum { DefaultEABIVersion = 0x05000000U };
  27     unsigned GetRelocTypeInner(const MCValue &Target,
  28                                const MCFixup &Fixup,
  29                                bool IsPCRel) const;
  30
  31
  32   public:
  33     ARMELFObjectWriter(uint8_t OSABI);
  34
  35     ~ARMELFObjectWriter() override;
  36
  37     unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
  38                           const MCFixup &Fixup, bool IsPCRel) const override;
  39
  40     bool needsRelocateWithSymbol(const MCSymbol &Sym,
  41                                  unsigned Type) const override;
  42   };
  43 }
  44
  45 ARMELFObjectWriter::ARMELFObjectWriter(uint8_t OSABI)
  46   : MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI,
  47                             ELF::EM_ARM,
  48                             /*HasRelocationAddend*/ false) {}
  49
  50 ARMELFObjectWriter::~ARMELFObjectWriter() {}
  51
  52 bool ARMELFObjectWriter::needsRelocateWithSymbol(const MCSymbol &Sym,
  53                                                  unsigned Type) const {
  54   // FIXME: This is extremely conservative. This really needs to use a
  55   // whitelist with a clear explanation for why each realocation needs to
  56   // point to the symbol, not to the section.
  57   switch (Type) {
  58   default:
  59     return true;
  60
  61   case ELF::R_ARM_PREL31:
  62   case ELF::R_ARM_ABS32:
  63     return false;
  64   }
  65 }
  66
  67 // Need to examine the Fixup when determining whether to
  68 // emit the relocation as an explicit symbol or as a section relative
  69 // offset
  70 unsigned ARMELFObjectWriter::getRelocType(MCContext &Ctx, const MCValue &Target,
  71                                           const MCFixup &Fixup,
  72                                           bool IsPCRel) const {
  73   return GetRelocTypeInner(Target, Fixup, IsPCRel);
  74 }
  75
  76 unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
  77                                                const MCFixup &Fixup,
  78                                                bool IsPCRel) const  {
  79   MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
  80
  81   unsigned Type = 0;
  82   if (IsPCRel) {
  83     switch ((unsigned)Fixup.getKind()) {
  84     default:
  85       report_fatal_error("unsupported relocation on symbol");
  86       return ELF::R_ARM_NONE;
  87     case FK_Data_4:
  88       switch (Modifier) {
  89       default: llvm_unreachable("Unsupported Modifier");
  90       case MCSymbolRefExpr::VK_None:
  91         Type = ELF::R_ARM_REL32;
  92         break;
  93       case MCSymbolRefExpr::VK_TLSGD:
  94         llvm_unreachable("unimplemented");
  95       case MCSymbolRefExpr::VK_GOTTPOFF:
  96         Type = ELF::R_ARM_TLS_IE32;
  97         break;
  98       case MCSymbolRefExpr::VK_ARM_GOT_PREL:
  99         Type = ELF::R_ARM_GOT_PREL;
 100         break;
 101       case MCSymbolRefExpr::VK_ARM_PREL31:
 102         Type = ELF::R_ARM_PREL31;
 103         break;
 104       }
 105       break;
 106     case ARM::fixup_arm_blx:
 107     case ARM::fixup_arm_uncondbl:
 108       switch (Modifier) {
 109       case MCSymbolRefExpr::VK_PLT:
 110         Type = ELF::R_ARM_CALL;
 111         break;
 112       case MCSymbolRefExpr::VK_TLSCALL:
 113         Type = ELF::R_ARM_TLS_CALL;
 114         break;
 115       default:
 116         Type = ELF::R_ARM_CALL;
 117         break;
 118       }
 119       break;
 120     case ARM::fixup_arm_condbl:
 121     case ARM::fixup_arm_condbranch:
 122     case ARM::fixup_arm_uncondbranch:
 123       Type = ELF::R_ARM_JUMP24;
 124       break;
 125     case ARM::fixup_t2_condbranch:
 126       Type = ELF::R_ARM_THM_JUMP19;
 127       break;
 128     case ARM::fixup_t2_uncondbranch:
 129       Type = ELF::R_ARM_THM_JUMP24;
 130       break;
 131     case ARM::fixup_arm_movt_hi16:
 132       Type = ELF::R_ARM_MOVT_PREL;
 133       break;
 134     case ARM::fixup_arm_movw_lo16:
 135       Type = ELF::R_ARM_MOVW_PREL_NC;
 136       break;
 137     case ARM::fixup_t2_movt_hi16:
 138       Type = ELF::R_ARM_THM_MOVT_PREL;
 139       break;
 140     case ARM::fixup_t2_movw_lo16:
 141       Type = ELF::R_ARM_THM_MOVW_PREL_NC;
 142       break;
 143     case ARM::fixup_arm_thumb_br:
 144       Type = ELF::R_ARM_THM_JUMP11;
 145       break;
 146     case ARM::fixup_arm_thumb_bcc:
 147       Type = ELF::R_ARM_THM_JUMP8;
 148       break;
 149     case ARM::fixup_arm_thumb_bl:
 150     case ARM::fixup_arm_thumb_blx:
 151       switch (Modifier) {
 152       case MCSymbolRefExpr::VK_TLSCALL:
 153         Type = ELF::R_ARM_THM_TLS_CALL;
 154         break;
 155       default:
 156         Type = ELF::R_ARM_THM_CALL;
 157         break;
 158       }
 159       break;
 160     }
 161   } else {
 162     switch ((unsigned)Fixup.getKind()) {
 163     default:
 164       report_fatal_error("unsupported relocation on symbol");
 165       return ELF::R_ARM_NONE;
 166     case FK_Data_1:
 167       switch (Modifier) {
 168       default: llvm_unreachable("unsupported Modifier");
 169       case MCSymbolRefExpr::VK_None:
 170         Type = ELF::R_ARM_ABS8;
 171         break;
 172       }
 173       break;
 174     case FK_Data_2:
 175       switch (Modifier) {
 176       default: llvm_unreachable("unsupported modifier");
 177       case MCSymbolRefExpr::VK_None:
 178         Type = ELF::R_ARM_ABS16;
 179         break;
 180       }
 181       break;
 182     case FK_Data_4:
 183       switch (Modifier) {
 184       default: llvm_unreachable("Unsupported Modifier");
 185       case MCSymbolRefExpr::VK_ARM_NONE:
 186         Type = ELF::R_ARM_NONE;
 187         break;
 188       case MCSymbolRefExpr::VK_GOT:
 189         Type = ELF::R_ARM_GOT_BREL;
 190         break;
 191       case MCSymbolRefExpr::VK_TLSGD:
 192         Type = ELF::R_ARM_TLS_GD32;
 193         break;
 194       case MCSymbolRefExpr::VK_TPOFF:
 195         Type = ELF::R_ARM_TLS_LE32;
 196         break;
 197       case MCSymbolRefExpr::VK_GOTTPOFF:
 198         Type = ELF::R_ARM_TLS_IE32;
 199         break;
 200       case MCSymbolRefExpr::VK_None:
 201         Type = ELF::R_ARM_ABS32;
 202         break;
 203       case MCSymbolRefExpr::VK_GOTOFF:
 204         Type = ELF::R_ARM_GOTOFF32;
 205         break;
 206       case MCSymbolRefExpr::VK_ARM_GOT_PREL:
 207         Type = ELF::R_ARM_GOT_PREL;
 208         break;
 209       case MCSymbolRefExpr::VK_ARM_TARGET1:
 210         Type = ELF::R_ARM_TARGET1;
 211         break;
 212       case MCSymbolRefExpr::VK_ARM_TARGET2:
 213         Type = ELF::R_ARM_TARGET2;
 214         break;
 215       case MCSymbolRefExpr::VK_ARM_PREL31:
 216         Type = ELF::R_ARM_PREL31;
 217         break;
 218       case MCSymbolRefExpr::VK_ARM_SBREL:
 219         Type = ELF::R_ARM_SBREL32;
 220         break;
 221       case MCSymbolRefExpr::VK_ARM_TLSLDO:
 222         Type = ELF::R_ARM_TLS_LDO32;
 223         break;
 224       case MCSymbolRefExpr::VK_TLSCALL:
 225         Type = ELF::R_ARM_TLS_CALL;
 226         break;
 227       case MCSymbolRefExpr::VK_TLSDESC:
 228         Type = ELF::R_ARM_TLS_GOTDESC;
 229         break;
 230       case MCSymbolRefExpr::VK_TLSLDM:
 231         Type = ELF::R_ARM_TLS_LDM32;
 232         break;
 233       case MCSymbolRefExpr::VK_ARM_TLSDESCSEQ:
 234         Type = ELF::R_ARM_TLS_DESCSEQ;
 235         break;
 236       }
 237       break;
 238     case ARM::fixup_arm_ldst_pcrel_12:
 239     case ARM::fixup_arm_pcrel_10:
 240     case ARM::fixup_arm_adr_pcrel_12:
 241     case ARM::fixup_arm_thumb_bl:
 242     case ARM::fixup_arm_thumb_cb:
 243     case ARM::fixup_arm_thumb_cp:
 244     case ARM::fixup_arm_thumb_br:
 245       llvm_unreachable("Unimplemented");
 246     case ARM::fixup_arm_condbranch:
 247     case ARM::fixup_arm_uncondbranch:
 248       Type = ELF::R_ARM_JUMP24;
 249       break;
 250     case ARM::fixup_arm_movt_hi16:
 251       switch (Modifier) {
 252       default: llvm_unreachable("Unsupported Modifier");
 253       case MCSymbolRefExpr::VK_None:
 254         Type = ELF::R_ARM_MOVT_ABS;
 255         break;
 256       case MCSymbolRefExpr::VK_ARM_SBREL:
 257         Type = ELF:: R_ARM_MOVT_BREL;
 258         break;
 259       }
 260       break;
 261     case ARM::fixup_arm_movw_lo16:
 262       switch (Modifier) {
 263       default: llvm_unreachable("Unsupported Modifier");
 264       case MCSymbolRefExpr::VK_None:
 265         Type = ELF::R_ARM_MOVW_ABS_NC;
 266         break;
 267       case MCSymbolRefExpr::VK_ARM_SBREL:
 268         Type = ELF:: R_ARM_MOVW_BREL_NC;
 269         break;
 270       }
 271       break;
 272     case ARM::fixup_t2_movt_hi16:
 273       Type = ELF::R_ARM_THM_MOVT_ABS;
 274       break;
 275     case ARM::fixup_t2_movw_lo16:
 276       Type = ELF::R_ARM_THM_MOVW_ABS_NC;
 277       break;
 278     }
 279   }
 280
 281   return Type;
 282 }
 283
 284 MCObjectWriter *llvm::createARMELFObjectWriter(raw_pwrite_stream &OS,
 285                                                uint8_t OSABI,
 286                                                bool IsLittleEndian) {
 287   MCELFObjectTargetWriter *MOTW = new ARMELFObjectWriter(OSABI);
 288   return createELFObjectWriter(MOTW, OS, IsLittleEndian);
 289 }