lib/MC/MCPureStreamer.cpp

   1 //===- lib/MC/MCPureStreamer.cpp - MC "Pure" Object Output ----------------===//
   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/MC/MCStreamer.h"
  11 #include "llvm/MC/MCAssembler.h"
  12 #include "llvm/MC/MCCodeEmitter.h"
  13 #include "llvm/MC/MCContext.h"
  14 #include "llvm/MC/MCExpr.h"
  15 #include "llvm/MC/MCObjectStreamer.h"
  16 // FIXME: Remove this.
  17 #include "llvm/MC/MCSectionMachO.h"
  18 #include "llvm/MC/MCSymbol.h"
  19 #include "llvm/Support/ErrorHandling.h"
  20
  21 using namespace llvm;
  22
  23 namespace {
  24
  25 class MCPureStreamer : public MCObjectStreamer {
  26 private:
  27   virtual void EmitInstToFragment(const MCInst &Inst);
  28   virtual void EmitInstToData(const MCInst &Inst);
  29
  30 public:
  31   MCPureStreamer(MCContext &Context, TargetAsmBackend &TAB,
  32                  raw_ostream &OS, MCCodeEmitter *Emitter)
  33     : MCObjectStreamer(Context, TAB, OS, Emitter) {}
  34
  35   /// @name MCStreamer Interface
  36   /// @{
  37
  38   virtual void InitSections();
  39   virtual void EmitLabel(MCSymbol *Symbol);
  40   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
  41   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
  42                             unsigned Size = 0, unsigned ByteAlignment = 0);
  43   virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
  44   virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
  45                                     unsigned ValueSize = 1,
  46                                     unsigned MaxBytesToEmit = 0);
  47   virtual void EmitCodeAlignment(unsigned ByteAlignment,
  48                                  unsigned MaxBytesToEmit = 0);
  49   virtual void EmitValueToOffset(const MCExpr *Offset,
  50                                  unsigned char Value = 0);
  51   virtual void Finish();
  52
  53
  54   virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) {
  55     report_fatal_error("unsupported directive in pure streamer");
  56   }
  57   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) {
  58     report_fatal_error("unsupported directive in pure streamer");
  59   }
  60   virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
  61                               uint64_t Size, unsigned ByteAlignment = 0) {
  62     report_fatal_error("unsupported directive in pure streamer");
  63   }
  64   virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
  65     report_fatal_error("unsupported directive in pure streamer");
  66   }
  67   virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
  68                                 unsigned ByteAlignment) {
  69     report_fatal_error("unsupported directive in pure streamer");
  70   }
  71   virtual void EmitThumbFunc(MCSymbol *Func) {
  72     report_fatal_error("unsupported directive in pure streamer");
  73   }
  74   virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {
  75     report_fatal_error("unsupported directive in pure streamer");
  76   }
  77   virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
  78     report_fatal_error("unsupported directive in pure streamer");
  79   }
  80   virtual void EmitCOFFSymbolType(int Type) {
  81     report_fatal_error("unsupported directive in pure streamer");
  82   }
  83   virtual void EndCOFFSymbolDef() {
  84     report_fatal_error("unsupported directive in pure streamer");
  85   }
  86   virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
  87     report_fatal_error("unsupported directive in pure streamer");
  88   }
  89   virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
  90     report_fatal_error("unsupported directive in pure streamer");
  91   }
  92   virtual void EmitFileDirective(StringRef Filename) {
  93     report_fatal_error("unsupported directive in pure streamer");
  94   }
  95   virtual bool EmitDwarfFileDirective(unsigned FileNo, StringRef Filename) {
  96     report_fatal_error("unsupported directive in pure streamer");
  97     return false;
  98   }
  99
 100   /// @}
 101 };
 102
 103 } // end anonymous namespace.
 104
 105 void MCPureStreamer::InitSections() {
 106   // FIMXE: To what!?
 107   SwitchSection(getContext().getMachOSection("__TEXT", "__text",
 108                                     MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 109                                     0, SectionKind::getText()));
 110
 111 }
 112
 113 void MCPureStreamer::EmitLabel(MCSymbol *Symbol) {
 114   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
 115   assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
 116   assert(getCurrentSection() && "Cannot emit before setting section!");
 117
 118   Symbol->setSection(*getCurrentSection());
 119
 120   MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
 121
 122   // We have to create a new fragment if this is an atom defining symbol,
 123   // fragments cannot span atoms.
 124   if (getAssembler().isSymbolLinkerVisible(SD.getSymbol()))
 125     new MCDataFragment(getCurrentSectionData());
 126
 127   // FIXME: This is wasteful, we don't necessarily need to create a data
 128   // fragment. Instead, we should mark the symbol as pointing into the data
 129   // fragment if it exists, otherwise we should just queue the label and set its
 130   // fragment pointer when we emit the next fragment.
 131   MCDataFragment *F = getOrCreateDataFragment();
 132   assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
 133   SD.setFragment(F);
 134   SD.setOffset(F->getContents().size());
 135 }
 136
 137 void MCPureStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
 138   // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
 139   // MCObjectStreamer.
 140   // FIXME: Lift context changes into super class.
 141   getAssembler().getOrCreateSymbolData(*Symbol);
 142   Symbol->setVariableValue(AddValueSymbols(Value));
 143 }
 144
 145 void MCPureStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
 146                                   unsigned Size, unsigned ByteAlignment) {
 147   report_fatal_error("not yet implemented in pure streamer");
 148 }
 149
 150 void MCPureStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
 151   // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
 152   // MCObjectStreamer.
 153   getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
 154 }
 155
 156 void MCPureStreamer::EmitValueToAlignment(unsigned ByteAlignment,
 157                                           int64_t Value, unsigned ValueSize,
 158                                           unsigned MaxBytesToEmit) {
 159   // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
 160   // MCObjectStreamer.
 161   if (MaxBytesToEmit == 0)
 162     MaxBytesToEmit = ByteAlignment;
 163   new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
 164                       getCurrentSectionData());
 165
 166   // Update the maximum alignment on the current section if necessary.
 167   if (ByteAlignment > getCurrentSectionData()->getAlignment())
 168     getCurrentSectionData()->setAlignment(ByteAlignment);
 169 }
 170
 171 void MCPureStreamer::EmitCodeAlignment(unsigned ByteAlignment,
 172                                        unsigned MaxBytesToEmit) {
 173   // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
 174   // MCObjectStreamer.
 175   if (MaxBytesToEmit == 0)
 176     MaxBytesToEmit = ByteAlignment;
 177   MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
 178                                            getCurrentSectionData());
 179   F->setEmitNops(true);
 180
 181   // Update the maximum alignment on the current section if necessary.
 182   if (ByteAlignment > getCurrentSectionData()->getAlignment())
 183     getCurrentSectionData()->setAlignment(ByteAlignment);
 184 }
 185
 186 void MCPureStreamer::EmitValueToOffset(const MCExpr *Offset,
 187                                        unsigned char Value) {
 188   new MCOrgFragment(*Offset, Value, getCurrentSectionData());
 189 }
 190
 191 void MCPureStreamer::EmitInstToFragment(const MCInst &Inst) {
 192   MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
 193
 194   // Add the fixups and data.
 195   //
 196   // FIXME: Revisit this design decision when relaxation is done, we may be
 197   // able to get away with not storing any extra data in the MCInst.
 198   SmallVector<MCFixup, 4> Fixups;
 199   SmallString<256> Code;
 200   raw_svector_ostream VecOS(Code);
 201   getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
 202   VecOS.flush();
 203
 204   IF->getCode() = Code;
 205   IF->getFixups() = Fixups;
 206 }
 207
 208 void MCPureStreamer::EmitInstToData(const MCInst &Inst) {
 209   MCDataFragment *DF = getOrCreateDataFragment();
 210
 211   SmallVector<MCFixup, 4> Fixups;
 212   SmallString<256> Code;
 213   raw_svector_ostream VecOS(Code);
 214   getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
 215   VecOS.flush();
 216
 217   // Add the fixups and data.
 218   for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
 219     Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
 220     DF->addFixup(Fixups[i]);
 221   }
 222   DF->getContents().append(Code.begin(), Code.end());
 223 }
 224
 225 void MCPureStreamer::Finish() {
 226   // FIXME: Handle DWARF tables?
 227
 228   this->MCObjectStreamer::Finish();
 229 }
 230
 231 MCStreamer *llvm::createPureStreamer(MCContext &Context, TargetAsmBackend &TAB,
 232                                      raw_ostream &OS, MCCodeEmitter *CE) {
 233   return new MCPureStreamer(Context, TAB, OS, CE);
 234 }