lib/Target/ARM/ARMAsmBackend.cpp

   1 //===-- ARMAsmBackend.cpp - ARM 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 "ARM.h"
  12 //FIXME: add #include "ARMFixupKinds.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 namespace {
  30 class ARMAsmBackend : public TargetAsmBackend {
  31 public:
  32   ARMAsmBackend(const Target &T)
  33     : TargetAsmBackend(T) {
  34   }
  35
  36   bool MayNeedRelaxation(const MCInst &Inst) const;
  37
  38   void RelaxInstruction(const MCInst &Inst, MCInst &Res) const;
  39
  40   bool WriteNopData(uint64_t Count, MCObjectWriter *OW) const;
  41
  42   unsigned getPointerSize() const {
  43     return 4;
  44   }
  45 };
  46
  47 bool ARMAsmBackend::MayNeedRelaxation(const MCInst &Inst) const {
  48   // FIXME: Thumb targets, different move constant targets..
  49   return false;
  50 }
  51
  52 void ARMAsmBackend::RelaxInstruction(const MCInst &Inst, MCInst &Res) const {
  53   assert(0 && "ARMAsmBackend::RelaxInstruction() unimplemented");
  54   return;
  55 }
  56
  57 bool ARMAsmBackend::WriteNopData(uint64_t Count, MCObjectWriter *OW) const {
  58   if ((Count % 4) != 0) {
  59     // Fixme: % 2 for Thumb?
  60     return false;
  61   }
  62   return true;
  63 }
  64 } // end anonymous namespace
  65
  66 namespace {
  67 // FIXME: This should be in a separate file.
  68 // ELF is an ELF of course...
  69 class ELFARMAsmBackend : public ARMAsmBackend {
  70   MCELFObjectFormat Format;
  71
  72 public:
  73   Triple::OSType OSType;
  74   ELFARMAsmBackend(const Target &T, Triple::OSType _OSType)
  75     : ARMAsmBackend(T), OSType(_OSType) {
  76     HasScatteredSymbols = true;
  77   }
  78
  79   virtual const MCObjectFormat &getObjectFormat() const {
  80     return Format;
  81   }
  82
  83   void ApplyFixup(const MCFixup &Fixup, MCDataFragment &DF,
  84                   uint64_t Value) const;
  85
  86   bool isVirtualSection(const MCSection &Section) const {
  87     const MCSectionELF &SE = static_cast<const MCSectionELF&>(Section);
  88     return SE.getType() == MCSectionELF::SHT_NOBITS;
  89   }
  90
  91   MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
  92     return new ELFObjectWriter(OS, /*Is64Bit=*/false,
  93                                OSType, ELF::EM_ARM,
  94                                /*IsLittleEndian=*/true,
  95                                /*HasRelocationAddend=*/false);
  96   }
  97 };
  98
  99 // Fixme: can we raise this to share code between Darwin and ELF?
 100 void ELFARMAsmBackend::ApplyFixup(const MCFixup &Fixup, MCDataFragment &DF,
 101                                   uint64_t Value) const {
 102   assert(0 && "ELFARMAsmBackend::ApplyFixup() unimplemented");
 103 }
 104
 105 // FIXME: This should be in a separate file.
 106 class DarwinARMAsmBackend : public ARMAsmBackend {
 107   MCMachOObjectFormat Format;
 108
 109 public:
 110   DarwinARMAsmBackend(const Target &T)
 111     : ARMAsmBackend(T) {
 112     HasScatteredSymbols = true;
 113     assert(0 && "DarwinARMAsmBackend::DarwinARMAsmBackend() unimplemented");
 114   }
 115
 116   virtual const MCObjectFormat &getObjectFormat() const {
 117     return Format;
 118   }
 119
 120   void ApplyFixup(const MCFixup &Fixup, MCDataFragment &DF,
 121                   uint64_t Value) const;
 122
 123   bool isVirtualSection(const MCSection &Section) const {
 124     const MCSectionMachO &SMO = static_cast<const MCSectionMachO&>(Section);
 125     return (SMO.getType() == MCSectionMachO::S_ZEROFILL ||
 126             SMO.getType() == MCSectionMachO::S_GB_ZEROFILL ||
 127             SMO.getType() == MCSectionMachO::S_THREAD_LOCAL_ZEROFILL);
 128   }
 129
 130   MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
 131     return new MachObjectWriter(OS, /*Is64Bit=*/false);
 132   }
 133
 134   virtual bool doesSectionRequireSymbols(const MCSection &Section) const {
 135     return false;
 136   }
 137 };
 138
 139 void DarwinARMAsmBackend::ApplyFixup(const MCFixup &Fixup, MCDataFragment &DF,
 140                                   uint64_t Value) const {
 141   assert(0 && "DarwinARMAsmBackend::ApplyFixup() unimplemented");
 142 }
 143 } // end anonymous namespace
 144
 145 TargetAsmBackend *llvm::createARMAsmBackend(const Target &T,
 146                                             const std::string &TT) {
 147   switch (Triple(TT).getOS()) {
 148   case Triple::Darwin:
 149     return new DarwinARMAsmBackend(T);
 150   case Triple::MinGW32:
 151   case Triple::Cygwin:
 152   case Triple::Win32:
 153     assert(0 && "Windows not supported on ARM");
 154   default:
 155     return new ELFARMAsmBackend(T, Triple(TT).getOS());
 156   }
 157 }