lib/Target/MBlaze/MBlazeAsmBackend.cpp

   1 //===-- MBlazeAsmBackend.cpp - MBlaze Assembler Backend -------------------===//
   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 "llvm/Target/TargetAsmBackend.h"
  11 #include "MBlaze.h"
  12 #include "MBlazeFixupKinds.h"
  13 #include "llvm/ADT/Twine.h"
  14 #include "llvm/MC/ELFObjectWriter.h"
  15 #include "llvm/MC/MCAssembler.h"
  16 #include "llvm/MC/MCExpr.h"
  17 #include "llvm/MC/MCObjectFormat.h"
  18 #include "llvm/MC/MCObjectWriter.h"
  19 #include "llvm/MC/MCSectionELF.h"
  20 #include "llvm/MC/MCSectionMachO.h"
  21 #include "llvm/MC/MachObjectWriter.h"
  22 #include "llvm/Support/ELF.h"
  23 #include "llvm/Support/ErrorHandling.h"
  24 #include "llvm/Support/raw_ostream.h"
  25 #include "llvm/Target/TargetRegistry.h"
  26 #include "llvm/Target/TargetAsmBackend.h"
  27 using namespace llvm;
  28
  29 static unsigned getFixupKindSize(unsigned Kind) {
  30   switch (Kind) {
  31   default: assert(0 && "invalid fixup kind!");
  32   case FK_Data_1: return 1;
  33   case MBlaze::reloc_pcrel_2byte:
  34   case FK_Data_2: return 2;
  35   case MBlaze::reloc_pcrel_4byte:
  36   case FK_Data_4: return 4;
  37   case FK_Data_8: return 8;
  38   }
  39 }
  40
  41
  42 namespace {
  43 class MBlazeAsmBackend : public TargetAsmBackend {
  44 public:
  45   MBlazeAsmBackend(const Target &T)
  46     : TargetAsmBackend(T) {
  47   }
  48
  49   bool MayNeedRelaxation(const MCInst &Inst) const;
  50
  51   void RelaxInstruction(const MCInst &Inst, MCInst &Res) const;
  52
  53   bool WriteNopData(uint64_t Count, MCObjectWriter *OW) const;
  54
  55   unsigned getPointerSize() const {
  56     return 4;
  57   }
  58 };
  59
  60 bool MBlazeAsmBackend::MayNeedRelaxation(const MCInst &Inst) const {
  61   return false;
  62 }
  63
  64 void MBlazeAsmBackend::RelaxInstruction(const MCInst &Inst, MCInst &Res) const {
  65   assert(0 && "MBlazeAsmBackend::RelaxInstruction() unimplemented");
  66   return;
  67 }
  68
  69 bool MBlazeAsmBackend::WriteNopData(uint64_t Count, MCObjectWriter *OW) const {
  70   if ((Count % 4) != 0)
  71     return false;
  72
  73   for (uint64_t i = 0; i < Count; i += 4 )
  74       OW->Write32( 0x00000000 );
  75
  76   return true;
  77 }
  78 } // end anonymous namespace
  79
  80 namespace {
  81 // FIXME: This should be in a separate file.
  82 // ELF is an ELF of course...
  83 class ELFMBlazeAsmBackend : public MBlazeAsmBackend {
  84   MCELFObjectFormat Format;
  85
  86 public:
  87   Triple::OSType OSType;
  88   ELFMBlazeAsmBackend(const Target &T, Triple::OSType _OSType)
  89     : MBlazeAsmBackend(T), OSType(_OSType) {
  90     HasScatteredSymbols = true;
  91   }
  92
  93   virtual const MCObjectFormat &getObjectFormat() const {
  94     return Format;
  95   }
  96
  97
  98   void ApplyFixup(const MCFixup &Fixup, MCDataFragment &DF,
  99                   uint64_t Value) const;
 100
 101   bool isVirtualSection(const MCSection &Section) const {
 102     const MCSectionELF &SE = static_cast<const MCSectionELF&>(Section);
 103     return SE.getType() == MCSectionELF::SHT_NOBITS;
 104   }
 105
 106   MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
 107     return new ELFObjectWriter(OS, /*Is64Bit=*/false,
 108                                OSType, ELF::EM_MBLAZE,
 109                                /*IsLittleEndian=*/false,
 110                                /*HasRelocationAddend=*/true);
 111   }
 112 };
 113
 114 void ELFMBlazeAsmBackend::ApplyFixup(const MCFixup &Fixup, MCDataFragment &DF,
 115                                      uint64_t Value) const {
 116   unsigned Size = getFixupKindSize(Fixup.getKind());
 117
 118   assert(Fixup.getOffset() + Size <= DF.getContents().size() &&
 119          "Invalid fixup offset!");
 120
 121   char *data = DF.getContents().data() + Fixup.getOffset();
 122   switch (Size) {
 123   default: llvm_unreachable( "Cannot fixup unknown value." );
 124   case 1:  llvm_unreachable( "Cannot fixup 1 byte value." );
 125   case 8:  llvm_unreachable( "Cannot fixup 8 byte value." );
 126
 127   case 4:
 128     *(data+7) = uint8_t(Value);
 129     *(data+6) = uint8_t(Value >> 8);
 130     *(data+3) = uint8_t(Value >> 16);
 131     *(data+2) = uint8_t(Value >> 24);
 132     break;
 133
 134   case 2:
 135     *(data+3) = uint8_t(Value >> 0);
 136     *(data+2) = uint8_t(Value >> 8);
 137   }
 138 }
 139 } // end anonymous namespace
 140
 141 TargetAsmBackend *llvm::createMBlazeAsmBackend(const Target &T,
 142                                             const std::string &TT) {
 143   switch (Triple(TT).getOS()) {
 144   case Triple::Darwin:
 145     assert(0 && "Mac not supported on MBlaze");
 146   case Triple::MinGW32:
 147   case Triple::Cygwin:
 148   case Triple::Win32:
 149     assert(0 && "Windows not supported on MBlaze");
 150   default:
 151     return new ELFMBlazeAsmBackend(T, Triple(TT).getOS());
 152   }
 153 }