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/MC/MCAsmBackend.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::EmitLabel(MCSymbol *Symbol) {
109  MCStreamer::EmitLabel(Symbol);
110
111  MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
112
113  // FIXME: This is wasteful, we don't necessarily need to create a data
114  // fragment. Instead, we should mark the symbol as pointing into the data
115  // fragment if it exists, otherwise we should just queue the label and set its
116  // fragment pointer when we emit the next fragment.
117  MCDataFragment *F = getOrCreateDataFragment();
118  assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
119  SD.setFragment(F);
120  SD.setOffset(F->getContents().size());
121}
122
123void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
124  int64_t IntValue;
125  if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
126    EmitULEB128IntValue(IntValue);
127    return;
128  }
129  Value = ForceExpAbs(Value);
130  new MCLEBFragment(*Value, false, getCurrentSectionData());
131}
132
133void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
134  int64_t IntValue;
135  if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
136    EmitSLEB128IntValue(IntValue);
137    return;
138  }
139  Value = ForceExpAbs(Value);
140  new MCLEBFragment(*Value, true, getCurrentSectionData());
141}
142
143void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
144                                         const MCSymbol *Symbol) {
145  report_fatal_error("This file format doesn't support weak aliases.");
146}
147
148void MCObjectStreamer::ChangeSection(const MCSection *Section) {
149  assert(Section && "Cannot switch to a null section!");
150
151  CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
152}
153
154void MCObjectStreamer::EmitInstruction(const MCInst &Inst) {
155  // Scan for values.
156  for (unsigned i = Inst.getNumOperands(); i--; )
157    if (Inst.getOperand(i).isExpr())
158      AddValueSymbols(Inst.getOperand(i).getExpr());
159
160  getCurrentSectionData()->setHasInstructions(true);
161
162  // Now that a machine instruction has been assembled into this section, make
163  // a line entry for any .loc directive that has been seen.
164  MCLineEntry::Make(this, getCurrentSection());
165
166  // If this instruction doesn't need relaxation, just emit it as data.
167  if (!getAssembler().getBackend().MayNeedRelaxation(Inst)) {
168    EmitInstToData(Inst);
169    return;
170  }
171
172  // Otherwise, if we are relaxing everything, relax the instruction as much as
173  // possible and emit it as data.
174  if (getAssembler().getRelaxAll()) {
175    MCInst Relaxed;
176    getAssembler().getBackend().RelaxInstruction(Inst, Relaxed);
177    while (getAssembler().getBackend().MayNeedRelaxation(Relaxed))
178      getAssembler().getBackend().RelaxInstruction(Relaxed, Relaxed);
179    EmitInstToData(Relaxed);
180    return;
181  }
182
183  // Otherwise emit to a separate fragment.
184  EmitInstToFragment(Inst);
185}
186
187void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst) {
188  MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
189
190  SmallString<128> Code;
191  raw_svector_ostream VecOS(Code);
192  getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups());
193  VecOS.flush();
194  IF->getCode().append(Code.begin(), Code.end());
195}
196
197void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
198                                                const MCSymbol *LastLabel,
199                                                const MCSymbol *Label,
200                                                unsigned PointerSize) {
201  if (!LastLabel) {
202    EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
203    return;
204  }
205  const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
206  int64_t Res;
207  if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
208    MCDwarfLineAddr::Emit(this, LineDelta, Res);
209    return;
210  }
211  AddrDelta = ForceExpAbs(AddrDelta);
212  new MCDwarfLineAddrFragment(LineDelta, *AddrDelta, getCurrentSectionData());
213}
214
215void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
216                                                 const MCSymbol *Label) {
217  const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
218  int64_t Res;
219  if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
220    MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
221    return;
222  }
223  AddrDelta = ForceExpAbs(AddrDelta);
224  new MCDwarfCallFrameFragment(*AddrDelta, getCurrentSectionData());
225}
226
227void MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
228                                        unsigned char Value) {
229  int64_t Res;
230  if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
231    new MCOrgFragment(*Offset, Value, getCurrentSectionData());
232    return;
233  }
234
235  MCSymbol *CurrentPos = getContext().CreateTempSymbol();
236  EmitLabel(CurrentPos);
237  MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
238  const MCExpr *Ref =
239    MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
240  const MCExpr *Delta =
241    MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
242
243  if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
244    report_fatal_error("expected assembly-time absolute expression");
245  EmitFill(Res, Value, 0);
246}
247
248void MCObjectStreamer::Finish() {
249  // Dump out the dwarf file & directory tables and line tables.
250  if (getContext().hasDwarfFiles())
251    MCDwarfFileTable::Emit(this);
252
253  getAssembler().Finish();
254}
255