lib/Target/SystemZ/MCTargetDesc/SystemZMCObjectWriter.cpp

   1 //===-- SystemZMCObjectWriter.cpp - SystemZ ELF writer --------------------===//
   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 "MCTargetDesc/SystemZMCFixups.h"
  10 #include "MCTargetDesc/SystemZMCTargetDesc.h"
  11 #include "llvm/BinaryFormat/ELF.h"
  12 #include "llvm/MC/MCELFObjectWriter.h"
  13 #include "llvm/MC/MCExpr.h"
  14 #include "llvm/MC/MCFixup.h"
  15 #include "llvm/MC/MCObjectWriter.h"
  16 #include "llvm/MC/MCValue.h"
  17 #include "llvm/Support/ErrorHandling.h"
  18 #include <cassert>
  19 #include <cstdint>
  20
  21 using namespace llvm;
  22
  23 namespace {
  24
  25 class SystemZObjectWriter : public MCELFObjectTargetWriter {
  26 public:
  27   SystemZObjectWriter(uint8_t OSABI);
  28   ~SystemZObjectWriter() override = default;
  29
  30 protected:
  31   // Override MCELFObjectTargetWriter.
  32   unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
  33                         const MCFixup &Fixup, bool IsPCRel) const override;
  34 };
  35
  36 } // end anonymous namespace
  37
  38 SystemZObjectWriter::SystemZObjectWriter(uint8_t OSABI)
  39   : MCELFObjectTargetWriter(/*Is64Bit=*/true, OSABI, ELF::EM_S390,
  40                             /*HasRelocationAddend=*/ true) {}
  41
  42 // Return the relocation type for an absolute value of MCFixupKind Kind.
  43 static unsigned getAbsoluteReloc(unsigned Kind) {
  44   switch (Kind) {
  45   case FK_Data_1: return ELF::R_390_8;
  46   case FK_Data_2: return ELF::R_390_16;
  47   case FK_Data_4: return ELF::R_390_32;
  48   case FK_Data_8: return ELF::R_390_64;
  49   }
  50   llvm_unreachable("Unsupported absolute address");
  51 }
  52
  53 // Return the relocation type for a PC-relative value of MCFixupKind Kind.
  54 static unsigned getPCRelReloc(unsigned Kind) {
  55   switch (Kind) {
  56   case FK_Data_2:                return ELF::R_390_PC16;
  57   case FK_Data_4:                return ELF::R_390_PC32;
  58   case FK_Data_8:                return ELF::R_390_PC64;
  59   case SystemZ::FK_390_PC12DBL:  return ELF::R_390_PC12DBL;
  60   case SystemZ::FK_390_PC16DBL:  return ELF::R_390_PC16DBL;
  61   case SystemZ::FK_390_PC24DBL:  return ELF::R_390_PC24DBL;
  62   case SystemZ::FK_390_PC32DBL:  return ELF::R_390_PC32DBL;
  63   }
  64   llvm_unreachable("Unsupported PC-relative address");
  65 }
  66
  67 // Return the R_390_TLS_LE* relocation type for MCFixupKind Kind.
  68 static unsigned getTLSLEReloc(unsigned Kind) {
  69   switch (Kind) {
  70   case FK_Data_4: return ELF::R_390_TLS_LE32;
  71   case FK_Data_8: return ELF::R_390_TLS_LE64;
  72   }
  73   llvm_unreachable("Unsupported absolute address");
  74 }
  75
  76 // Return the R_390_TLS_LDO* relocation type for MCFixupKind Kind.
  77 static unsigned getTLSLDOReloc(unsigned Kind) {
  78   switch (Kind) {
  79   case FK_Data_4: return ELF::R_390_TLS_LDO32;
  80   case FK_Data_8: return ELF::R_390_TLS_LDO64;
  81   }
  82   llvm_unreachable("Unsupported absolute address");
  83 }
  84
  85 // Return the R_390_TLS_LDM* relocation type for MCFixupKind Kind.
  86 static unsigned getTLSLDMReloc(unsigned Kind) {
  87   switch (Kind) {
  88   case FK_Data_4: return ELF::R_390_TLS_LDM32;
  89   case FK_Data_8: return ELF::R_390_TLS_LDM64;
  90   case SystemZ::FK_390_TLS_CALL: return ELF::R_390_TLS_LDCALL;
  91   }
  92   llvm_unreachable("Unsupported absolute address");
  93 }
  94
  95 // Return the R_390_TLS_GD* relocation type for MCFixupKind Kind.
  96 static unsigned getTLSGDReloc(unsigned Kind) {
  97   switch (Kind) {
  98   case FK_Data_4: return ELF::R_390_TLS_GD32;
  99   case FK_Data_8: return ELF::R_390_TLS_GD64;
 100   case SystemZ::FK_390_TLS_CALL: return ELF::R_390_TLS_GDCALL;
 101   }
 102   llvm_unreachable("Unsupported absolute address");
 103 }
 104
 105 // Return the PLT relocation counterpart of MCFixupKind Kind.
 106 static unsigned getPLTReloc(unsigned Kind) {
 107   switch (Kind) {
 108   case SystemZ::FK_390_PC12DBL: return ELF::R_390_PLT12DBL;
 109   case SystemZ::FK_390_PC16DBL: return ELF::R_390_PLT16DBL;
 110   case SystemZ::FK_390_PC24DBL: return ELF::R_390_PLT24DBL;
 111   case SystemZ::FK_390_PC32DBL: return ELF::R_390_PLT32DBL;
 112   }
 113   llvm_unreachable("Unsupported absolute address");
 114 }
 115
 116 unsigned SystemZObjectWriter::getRelocType(MCContext &Ctx,
 117                                            const MCValue &Target,
 118                                            const MCFixup &Fixup,
 119                                            bool IsPCRel) const {
 120   MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
 121   unsigned Kind = Fixup.getKind();
 122   switch (Modifier) {
 123   case MCSymbolRefExpr::VK_None:
 124     if (IsPCRel)
 125       return getPCRelReloc(Kind);
 126     return getAbsoluteReloc(Kind);
 127
 128   case MCSymbolRefExpr::VK_NTPOFF:
 129     assert(!IsPCRel && "NTPOFF shouldn't be PC-relative");
 130     return getTLSLEReloc(Kind);
 131
 132   case MCSymbolRefExpr::VK_INDNTPOFF:
 133     if (IsPCRel && Kind == SystemZ::FK_390_PC32DBL)
 134       return ELF::R_390_TLS_IEENT;
 135     llvm_unreachable("Only PC-relative INDNTPOFF accesses are supported for now");
 136
 137   case MCSymbolRefExpr::VK_DTPOFF:
 138     assert(!IsPCRel && "DTPOFF shouldn't be PC-relative");
 139     return getTLSLDOReloc(Kind);
 140
 141   case MCSymbolRefExpr::VK_TLSLDM:
 142     assert(!IsPCRel && "TLSLDM shouldn't be PC-relative");
 143     return getTLSLDMReloc(Kind);
 144
 145   case MCSymbolRefExpr::VK_TLSGD:
 146     assert(!IsPCRel && "TLSGD shouldn't be PC-relative");
 147     return getTLSGDReloc(Kind);
 148
 149   case MCSymbolRefExpr::VK_GOT:
 150     if (IsPCRel && Kind == SystemZ::FK_390_PC32DBL)
 151       return ELF::R_390_GOTENT;
 152     llvm_unreachable("Only PC-relative GOT accesses are supported for now");
 153
 154   case MCSymbolRefExpr::VK_PLT:
 155     assert(IsPCRel && "@PLT shouldt be PC-relative");
 156     return getPLTReloc(Kind);
 157
 158   default:
 159     llvm_unreachable("Modifier not supported");
 160   }
 161 }
 162
 163 std::unique_ptr<MCObjectTargetWriter>
 164 llvm::createSystemZObjectWriter(uint8_t OSABI) {
 165   return llvm::make_unique<SystemZObjectWriter>(OSABI);
 166 }