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/MCObjectStreamer.h"
11#include "llvm/MC/MCAsmBackend.h"
12#include "llvm/MC/MCAsmInfo.h"
13#include "llvm/MC/MCAssembler.h"
14#include "llvm/MC/MCCodeEmitter.h"
15#include "llvm/MC/MCContext.h"
16#include "llvm/MC/MCDwarf.h"
17#include "llvm/MC/MCExpr.h"
18#include "llvm/MC/MCObjectWriter.h"
19#include "llvm/MC/MCSymbol.h"
20#include "llvm/Support/ErrorHandling.h"
21using namespace llvm;
22
23MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB,
24                                   raw_ostream &OS, MCCodeEmitter *Emitter_)
25  : MCStreamer(Context),
26    Assembler(new MCAssembler(Context, TAB,
27                              *Emitter_, *TAB.createObjectWriter(OS),
28                              OS)),
29    CurSectionData(0)
30{
31}
32
33MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB,
34                                   raw_ostream &OS, MCCodeEmitter *Emitter_,
35                                   MCAssembler *_Assembler)
36  : MCStreamer(Context), Assembler(_Assembler), CurSectionData(0)
37{
38}
39
40MCObjectStreamer::~MCObjectStreamer() {
41  delete &Assembler->getBackend();
42  delete &Assembler->getEmitter();
43  delete &Assembler->getWriter();
44  delete Assembler;
45}
46
47MCFragment *MCObjectStreamer::getCurrentFragment() const {
48  assert(getCurrentSectionData() && "No current section!");
49
50  if (!getCurrentSectionData()->empty())
51    return &getCurrentSectionData()->getFragmentList().back();
52
53  return 0;
54}
55
56MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() const {
57  MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
58  if (!F)
59    F = new MCDataFragment(getCurrentSectionData());
60  return F;
61}
62
63const MCExpr *MCObjectStreamer::AddValueSymbols(const MCExpr *Value) {
64  switch (Value->getKind()) {
65  case MCExpr::Target:
66    cast<MCTargetExpr>(Value)->AddValueSymbols(Assembler);
67    break;
68
69  case MCExpr::Constant:
70    break;
71
72  case MCExpr::Binary: {
73    const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
74    AddValueSymbols(BE->getLHS());
75    AddValueSymbols(BE->getRHS());
76    break;
77  }
78
79  case MCExpr::SymbolRef:
80    Assembler->getOrCreateSymbolData(cast<MCSymbolRefExpr>(Value)->getSymbol());
81    break;
82
83  case MCExpr::Unary:
84    AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
85    break;
86  }
87
88  return Value;
89}
90
91void MCObjectStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
92                                     unsigned AddrSpace) {
93  assert(AddrSpace == 0 && "Address space must be 0!");
94  MCDataFragment *DF = getOrCreateDataFragment();
95
96  // Avoid fixups when possible.
97  int64_t AbsValue;
98  if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue, getAssembler())) {
99    EmitIntValue(AbsValue, Size, AddrSpace);
100    return;
101  }
102  DF->addFixup(MCFixup::Create(DF->getContents().size(),
103                               Value,
104                               MCFixup::getKindForSize(Size, false)));
105  DF->getContents().resize(DF->getContents().size() + Size, 0);
106}
107
108void MCObjectStreamer::EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
109  RecordProcStart(Frame);
110}
111
112void MCObjectStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
113  RecordProcEnd(Frame);
114}
115
116void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
117  MCStreamer::EmitLabel(Symbol);
118
119  MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
120
121  // FIXME: This is wasteful, we don't necessarily need to create a data
122  // fragment. Instead, we should mark the symbol as pointing into the data
123  // fragment if it exists, otherwise we should just queue the label and set its
124  // fragment pointer when we emit the next fragment.
125  MCDataFragment *F = getOrCreateDataFragment();
126  assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
127  SD.setFragment(F);
128  SD.setOffset(F->getContents().size());
129}
130
131void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
132  int64_t IntValue;
133  if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
134    EmitULEB128IntValue(IntValue);
135    return;
136  }
137  Value = ForceExpAbs(Value);
138  new MCLEBFragment(*Value, false, getCurrentSectionData());
139}
140
141void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
142  int64_t IntValue;
143  if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
144    EmitSLEB128IntValue(IntValue);
145    return;
146  }
147  Value = ForceExpAbs(Value);
148  new MCLEBFragment(*Value, true, getCurrentSectionData());
149}
150
151void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
152                                         const MCSymbol *Symbol) {
153  report_fatal_error("This file format doesn't support weak aliases.");
154}
155
156void MCObjectStreamer::ChangeSection(const MCSection *Section) {
157  assert(Section && "Cannot switch to a null section!");
158
159  CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
160}
161
162void MCObjectStreamer::EmitInstruction(const MCInst &Inst) {
163  // Scan for values.
164  for (unsigned i = Inst.getNumOperands(); i--; )
165    if (Inst.getOperand(i).isExpr())
166      AddValueSymbols(Inst.getOperand(i).getExpr());
167
168  getCurrentSectionData()->setHasInstructions(true);
169
170  // Now that a machine instruction has been assembled into this section, make
171  // a line entry for any .loc directive that has been seen.
172  MCLineEntry::Make(this, getCurrentSection());
173
174  // If this instruction doesn't need relaxation, just emit it as data.
175  if (!getAssembler().getBackend().mayNeedRelaxation(Inst)) {
176    EmitInstToData(Inst);
177    return;
178  }
179
180  // Otherwise, if we are relaxing everything, relax the instruction as much as
181  // possible and emit it as data.
182  if (getAssembler().getRelaxAll()) {
183    MCInst Relaxed;
184    getAssembler().getBackend().relaxInstruction(Inst, Relaxed);
185    while (getAssembler().getBackend().mayNeedRelaxation(Relaxed))
186      getAssembler().getBackend().relaxInstruction(Relaxed, Relaxed);
187    EmitInstToData(Relaxed);
188    return;
189  }
190
191  // Otherwise emit to a separate fragment.
192  EmitInstToFragment(Inst);
193}
194
195void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst) {
196  MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
197
198  SmallString<128> Code;
199  raw_svector_ostream VecOS(Code);
200  getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups());
201  VecOS.flush();
202  IF->getCode().append(Code.begin(), Code.end());
203}
204
205void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
206                                                const MCSymbol *LastLabel,
207                                                const MCSymbol *Label,
208                                                unsigned PointerSize) {
209  if (!LastLabel) {
210    EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
211    return;
212  }
213  const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
214  int64_t Res;
215  if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
216    MCDwarfLineAddr::Emit(this, LineDelta, Res);
217    return;
218  }
219  AddrDelta = ForceExpAbs(AddrDelta);
220  new MCDwarfLineAddrFragment(LineDelta, *AddrDelta, getCurrentSectionData());
221}
222
223void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
224                                                 const MCSymbol *Label) {
225  const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
226  int64_t Res;
227  if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
228    MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
229    return;
230  }
231  AddrDelta = ForceExpAbs(AddrDelta);
232  new MCDwarfCallFrameFragment(*AddrDelta, getCurrentSectionData());
233}
234
235bool MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
236                                         unsigned char Value) {
237  int64_t Res;
238  if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
239    new MCOrgFragment(*Offset, Value, getCurrentSectionData());
240    return false;
241  }
242
243  MCSymbol *CurrentPos = getContext().CreateTempSymbol();
244  EmitLabel(CurrentPos);
245  MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
246  const MCExpr *Ref =
247    MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
248  const MCExpr *Delta =
249    MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
250
251  if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
252    return true;
253  EmitFill(Res, Value, 0);
254  return false;
255}
256
257// Associate GPRel32 fixup with data and resize data area
258void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) {
259  MCDataFragment *DF = getOrCreateDataFragment();
260
261  DF->addFixup(MCFixup::Create(DF->getContents().size(), Value, FK_GPRel_4));
262  DF->getContents().resize(DF->getContents().size() + 4, 0);
263}
264
265// Associate GPRel32 fixup with data and resize data area
266void MCObjectStreamer::EmitGPRel64Value(const MCExpr *Value) {
267  MCDataFragment *DF = getOrCreateDataFragment();
268
269  DF->addFixup(MCFixup::Create(DF->getContents().size(), Value, FK_GPRel_4));
270  DF->getContents().resize(DF->getContents().size() + 8, 0);
271}
272
273void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue,
274                                unsigned AddrSpace) {
275  assert(AddrSpace == 0 && "Address space must be 0!");
276  // FIXME: A MCFillFragment would be more memory efficient but MCExpr has
277  //        problems evaluating expressions across multiple fragments.
278  getOrCreateDataFragment()->getContents().append(NumBytes, FillValue);
279}
280
281void MCObjectStreamer::FinishImpl() {
282  // Dump out the dwarf file & directory tables and line tables.
283  const MCSymbol *LineSectionSymbol = NULL;
284  if (getContext().hasDwarfFiles())
285    LineSectionSymbol = MCDwarfFileTable::Emit(this);
286
287  // If we are generating dwarf for assembly source files dump out the sections.
288  if (getContext().getGenDwarfForAssembly())
289    MCGenDwarfInfo::Emit(this, LineSectionSymbol);
290
291  getAssembler().Finish();
292}
293