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 "MBlazeELFWriterInfo.h"
  13 #include "llvm/ADT/Twine.h"
  14 #include "llvm/MC/MCAssembler.h"
  15 #include "llvm/MC/MCAsmLayout.h"
  16 #include "llvm/MC/MCELFObjectWriter.h"
  17 #include "llvm/MC/MCELFSymbolFlags.h"
  18 #include "llvm/MC/MCExpr.h"
  19 #include "llvm/MC/MCObjectWriter.h"
  20 #include "llvm/MC/MCSectionELF.h"
  21 #include "llvm/MC/MCSectionMachO.h"
  22 #include "llvm/MC/MCValue.h"
  23 #include "llvm/Support/ELF.h"
  24 #include "llvm/Support/ErrorHandling.h"
  25 #include "llvm/Support/raw_ostream.h"
  26 #include "llvm/Target/TargetRegistry.h"
  27 #include "llvm/Target/TargetAsmBackend.h"
  28 using namespace llvm;
  29
  30 static unsigned getFixupKindSize(unsigned Kind) {
  31   switch (Kind) {
  32   default: assert(0 && "invalid fixup kind!");
  33   case FK_Data_1: return 1;
  34   case FK_PCRel_2:
  35   case FK_Data_2: return 2;
  36   case FK_PCRel_4:
  37   case FK_Data_4: return 4;
  38   case FK_Data_8: return 8;
  39   }
  40 }
  41
  42
  43 namespace {
  44 class MBlazeELFObjectWriter : public MCELFObjectTargetWriter {
  45 public:
  46   MBlazeELFObjectWriter(Triple::OSType OSType)
  47     : MCELFObjectTargetWriter(/*is64Bit*/ false, OSType, ELF::EM_MBLAZE,
  48                               /*HasRelocationAddend*/ true) {}
  49 };
  50
  51 class MBlazeAsmBackend : public TargetAsmBackend {
  52 public:
  53   MBlazeAsmBackend(const Target &T)
  54     : TargetAsmBackend() {
  55   }
  56
  57   unsigned getNumFixupKinds() const {
  58     return 2;
  59   }
  60
  61   bool MayNeedRelaxation(const MCInst &Inst) const;
  62
  63   void RelaxInstruction(const MCInst &Inst, MCInst &Res) const;
  64
  65   bool WriteNopData(uint64_t Count, MCObjectWriter *OW) const;
  66
  67   unsigned getPointerSize() const {
  68     return 4;
  69   }
  70 };
  71
  72 static unsigned getRelaxedOpcode(unsigned Op) {
  73     switch (Op) {
  74     default:            return Op;
  75     case MBlaze::ADDIK: return MBlaze::ADDIK32;
  76     case MBlaze::ORI:   return MBlaze::ORI32;
  77     case MBlaze::BRLID: return MBlaze::BRLID32;
  78     }
  79 }
  80
  81 bool MBlazeAsmBackend::MayNeedRelaxation(const MCInst &Inst) const {
  82   if (getRelaxedOpcode(Inst.getOpcode()) == Inst.getOpcode())
  83     return false;
  84
  85   bool hasExprOrImm = false;
  86   for (unsigned i = 0; i < Inst.getNumOperands(); ++i)
  87     hasExprOrImm |= Inst.getOperand(i).isExpr();
  88
  89   return hasExprOrImm;
  90 }
  91
  92 void MBlazeAsmBackend::RelaxInstruction(const MCInst &Inst, MCInst &Res) const {
  93   Res = Inst;
  94   Res.setOpcode(getRelaxedOpcode(Inst.getOpcode()));
  95 }
  96
  97 bool MBlazeAsmBackend::WriteNopData(uint64_t Count, MCObjectWriter *OW) const {
  98   if ((Count % 4) != 0)
  99     return false;
 100
 101   for (uint64_t i = 0; i < Count; i += 4)
 102       OW->Write32(0x00000000);
 103
 104   return true;
 105 }
 106 } // end anonymous namespace
 107
 108 namespace {
 109 class ELFMBlazeAsmBackend : public MBlazeAsmBackend {
 110 public:
 111   Triple::OSType OSType;
 112   ELFMBlazeAsmBackend(const Target &T, Triple::OSType _OSType)
 113     : MBlazeAsmBackend(T), OSType(_OSType) { }
 114
 115   void ApplyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
 116                   uint64_t Value) const;
 117
 118   MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
 119     return createELFObjectWriter(new MBlazeELFObjectWriter(OSType), OS,
 120                                  /*IsLittleEndian*/ false);
 121   }
 122 };
 123
 124 void ELFMBlazeAsmBackend::ApplyFixup(const MCFixup &Fixup, char *Data,
 125                                      unsigned DataSize, uint64_t Value) const {
 126   unsigned Size = getFixupKindSize(Fixup.getKind());
 127
 128   assert(Fixup.getOffset() + Size <= DataSize &&
 129          "Invalid fixup offset!");
 130
 131   char *data = Data + Fixup.getOffset();
 132   switch (Size) {
 133   default: llvm_unreachable("Cannot fixup unknown value.");
 134   case 1:  llvm_unreachable("Cannot fixup 1 byte value.");
 135   case 8:  llvm_unreachable("Cannot fixup 8 byte value.");
 136
 137   case 4:
 138     *(data+7) = uint8_t(Value);
 139     *(data+6) = uint8_t(Value >> 8);
 140     *(data+3) = uint8_t(Value >> 16);
 141     *(data+2) = uint8_t(Value >> 24);
 142     break;
 143
 144   case 2:
 145     *(data+3) = uint8_t(Value >> 0);
 146     *(data+2) = uint8_t(Value >> 8);
 147   }
 148 }
 149 } // end anonymous namespace
 150
 151 TargetAsmBackend *llvm::createMBlazeAsmBackend(const Target &T,
 152                                             const std::string &TT) {
 153   Triple TheTriple(TT);
 154
 155   if (TheTriple.isOSDarwin())
 156     assert(0 && "Mac not supported on MBlaze");
 157
 158   if (TheTriple.isOSWindows())
 159     assert(0 && "Windows not supported on MBlaze");
 160
 161   return new ELFMBlazeAsmBackend(T, TheTriple.getOS());
 162 }