lib/MC/MCObjectStreamer.cpp

   1 //===- lib/MC/MCObjectStreamer.cpp - Object File MCStreamer Interface -----===//
   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/MCAsmInfo.h"
  11 #include "llvm/MC/MCObjectStreamer.h"
  12
  13 #include "llvm/Support/ErrorHandling.h"
  14 #include "llvm/MC/MCAssembler.h"
  15 #include "llvm/MC/MCCodeEmitter.h"
  16 #include "llvm/MC/MCContext.h"
  17 #include "llvm/MC/MCDwarf.h"
  18 #include "llvm/MC/MCExpr.h"
  19 #include "llvm/MC/MCSymbol.h"
  20 #include "llvm/Target/TargetAsmBackend.h"
  21 #include "llvm/Target/TargetAsmInfo.h"
  22 using namespace llvm;
  23
  24 MCObjectStreamer::MCObjectStreamer(MCContext &Context, TargetAsmBackend &TAB,
  25                                    raw_ostream &OS, MCCodeEmitter *Emitter_)
  26   : MCStreamer(Context),
  27     Assembler(new MCAssembler(Context, TAB,
  28                               *Emitter_, *TAB.createObjectWriter(OS),
  29                               OS)),
  30     CurSectionData(0)
  31 {
  32 }
  33
  34 MCObjectStreamer::MCObjectStreamer(MCContext &Context, TargetAsmBackend &TAB,
  35                                    raw_ostream &OS, MCCodeEmitter *Emitter_,
  36                                    MCAssembler *_Assembler)
  37   : MCStreamer(Context), Assembler(_Assembler), CurSectionData(0)
  38 {
  39 }
  40
  41 MCObjectStreamer::~MCObjectStreamer() {
  42   delete &Assembler->getBackend();
  43   delete &Assembler->getEmitter();
  44   delete &Assembler->getWriter();
  45   delete Assembler;
  46 }
  47
  48 MCFragment *MCObjectStreamer::getCurrentFragment() const {
  49   assert(getCurrentSectionData() && "No current section!");
  50
  51   if (!getCurrentSectionData()->empty())
  52     return &getCurrentSectionData()->getFragmentList().back();
  53
  54   return 0;
  55 }
  56
  57 MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() const {
  58   MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
  59   if (!F)
  60     F = new MCDataFragment(getCurrentSectionData());
  61   return F;
  62 }
  63
  64 const MCExpr *MCObjectStreamer::AddValueSymbols(const MCExpr *Value) {
  65   switch (Value->getKind()) {
  66   case MCExpr::Target:
  67     cast<MCTargetExpr>(Value)->AddValueSymbols(Assembler);
  68     break;
  69
  70   case MCExpr::Constant:
  71     break;
  72
  73   case MCExpr::Binary: {
  74     const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
  75     AddValueSymbols(BE->getLHS());
  76     AddValueSymbols(BE->getRHS());
  77     break;
  78   }
  79
  80   case MCExpr::SymbolRef:
  81     Assembler->getOrCreateSymbolData(cast<MCSymbolRefExpr>(Value)->getSymbol());
  82     break;
  83
  84   case MCExpr::Unary:
  85     AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
  86     break;
  87   }
  88
  89   return Value;
  90 }
  91
  92 void MCObjectStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
  93                                      unsigned AddrSpace) {
  94   assert(AddrSpace == 0 && "Address space must be 0!");
  95   MCDataFragment *DF = getOrCreateDataFragment();
  96
  97   // Avoid fixups when possible.
  98   int64_t AbsValue;
  99   if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue, getAssembler())) {
 100     EmitIntValue(AbsValue, Size, AddrSpace);
 101     return;
 102   }
 103   DF->addFixup(MCFixup::Create(DF->getContents().size(),
 104                                Value,
 105                                MCFixup::getKindForSize(Size, false)));
 106   DF->getContents().resize(DF->getContents().size() + Size, 0);
 107 }
 108
 109 void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
 110   MCStreamer::EmitLabel(Symbol);
 111
 112   MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
 113
 114   // FIXME: This is wasteful, we don't necessarily need to create a data
 115   // fragment. Instead, we should mark the symbol as pointing into the data
 116   // fragment if it exists, otherwise we should just queue the label and set its
 117   // fragment pointer when we emit the next fragment.
 118   MCDataFragment *F = getOrCreateDataFragment();
 119   assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
 120   SD.setFragment(F);
 121   SD.setOffset(F->getContents().size());
 122 }
 123
 124 void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
 125   int64_t IntValue;
 126   if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
 127     EmitULEB128IntValue(IntValue);
 128     return;
 129   }
 130   Value = ForceExpAbs(Value);
 131   new MCLEBFragment(*Value, false, getCurrentSectionData());
 132 }
 133
 134 void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
 135   int64_t IntValue;
 136   if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
 137     EmitSLEB128IntValue(IntValue);
 138     return;
 139   }
 140   Value = ForceExpAbs(Value);
 141   new MCLEBFragment(*Value, true, getCurrentSectionData());
 142 }
 143
 144 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
 145                                          const MCSymbol *Symbol) {
 146   report_fatal_error("This file format doesn't support weak aliases.");
 147 }
 148
 149 void MCObjectStreamer::ChangeSection(const MCSection *Section) {
 150   assert(Section && "Cannot switch to a null section!");
 151
 152   CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
 153 }
 154
 155 void MCObjectStreamer::EmitInstruction(const MCInst &Inst) {
 156   // Scan for values.
 157   for (unsigned i = Inst.getNumOperands(); i--; )
 158     if (Inst.getOperand(i).isExpr())
 159       AddValueSymbols(Inst.getOperand(i).getExpr());
 160
 161   getCurrentSectionData()->setHasInstructions(true);
 162
 163   // Now that a machine instruction has been assembled into this section, make
 164   // a line entry for any .loc directive that has been seen.
 165   MCLineEntry::Make(this, getCurrentSection());
 166
 167   // If this instruction doesn't need relaxation, just emit it as data.
 168   if (!getAssembler().getBackend().MayNeedRelaxation(Inst)) {
 169     EmitInstToData(Inst);
 170     return;
 171   }
 172
 173   // Otherwise, if we are relaxing everything, relax the instruction as much as
 174   // possible and emit it as data.
 175   if (getAssembler().getRelaxAll()) {
 176     MCInst Relaxed;
 177     getAssembler().getBackend().RelaxInstruction(Inst, Relaxed);
 178     while (getAssembler().getBackend().MayNeedRelaxation(Relaxed))
 179       getAssembler().getBackend().RelaxInstruction(Relaxed, Relaxed);
 180     EmitInstToData(Relaxed);
 181     return;
 182   }
 183
 184   // Otherwise emit to a separate fragment.
 185   EmitInstToFragment(Inst);
 186 }
 187
 188 void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst) {
 189   MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
 190
 191   SmallString<128> Code;
 192   raw_svector_ostream VecOS(Code);
 193   getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups());
 194   VecOS.flush();
 195   IF->getCode().append(Code.begin(), Code.end());
 196 }
 197
 198 void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
 199                                                 const MCSymbol *LastLabel,
 200                                                 const MCSymbol *Label) {
 201   if (!LastLabel) {
 202     int PointerSize = getContext().getTargetAsmInfo().getPointerSize();
 203     EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
 204     return;
 205   }
 206   const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
 207   int64_t Res;
 208   if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
 209     MCDwarfLineAddr::Emit(this, LineDelta, Res);
 210     return;
 211   }
 212   AddrDelta = ForceExpAbs(AddrDelta);
 213   new MCDwarfLineAddrFragment(LineDelta, *AddrDelta, getCurrentSectionData());
 214 }
 215
 216 void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
 217                                                  const MCSymbol *Label) {
 218   const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
 219   int64_t Res;
 220   if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
 221     MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
 222     return;
 223   }
 224   AddrDelta = ForceExpAbs(AddrDelta);
 225   new MCDwarfCallFrameFragment(*AddrDelta, getCurrentSectionData());
 226 }
 227
 228 void MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
 229                                         unsigned char Value) {
 230   int64_t Res;
 231   if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
 232     new MCOrgFragment(*Offset, Value, getCurrentSectionData());
 233     return;
 234   }
 235
 236   MCSymbol *CurrentPos = getContext().CreateTempSymbol();
 237   EmitLabel(CurrentPos);
 238   MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
 239   const MCExpr *Ref =
 240     MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
 241   const MCExpr *Delta =
 242     MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
 243
 244   if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
 245     report_fatal_error("expected assembly-time absolute expression");
 246   EmitFill(Res, Value, 0);
 247 }
 248
 249 void MCObjectStreamer::Finish() {
 250   // Dump out the dwarf file & directory tables and line tables.
 251   if (getContext().hasDwarfFiles())
 252     MCDwarfFileTable::Emit(this);
 253
 254   getAssembler().Finish();
 255 }