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"
21 using namespace llvm;
22
MCObjectStreamer(MCContext & Context,MCAsmBackend & TAB,raw_ostream & OS,MCCodeEmitter * Emitter_)23 MCObjectStreamer::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
MCObjectStreamer(MCContext & Context,MCAsmBackend & TAB,raw_ostream & OS,MCCodeEmitter * Emitter_,MCAssembler * _Assembler)33 MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB,
34 raw_ostream &OS, MCCodeEmitter *Emitter_,
35 MCAssembler *_Assembler)
36 : MCStreamer(Context), Assembler(_Assembler), CurSectionData(0)
37 {
38 }
39
~MCObjectStreamer()40 MCObjectStreamer::~MCObjectStreamer() {
41 delete &Assembler->getBackend();
42 delete &Assembler->getEmitter();
43 delete &Assembler->getWriter();
44 delete Assembler;
45 }
46
getCurrentFragment() const47 MCFragment *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
getOrCreateDataFragment() const56 MCDataFragment *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
AddValueSymbols(const MCExpr * Value)63 const 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
EmitValueImpl(const MCExpr * Value,unsigned Size,unsigned AddrSpace)91 void 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
EmitCFIStartProcImpl(MCDwarfFrameInfo & Frame)108 void MCObjectStreamer::EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
109 RecordProcStart(Frame);
110 }
111
EmitCFIEndProcImpl(MCDwarfFrameInfo & Frame)112 void MCObjectStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
113 RecordProcEnd(Frame);
114 }
115
EmitLabel(MCSymbol * Symbol)116 void 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
EmitULEB128Value(const MCExpr * Value)131 void 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
EmitSLEB128Value(const MCExpr * Value)141 void 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
EmitWeakReference(MCSymbol * Alias,const MCSymbol * Symbol)151 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
152 const MCSymbol *Symbol) {
153 report_fatal_error("This file format doesn't support weak aliases.");
154 }
155
ChangeSection(const MCSection * Section)156 void MCObjectStreamer::ChangeSection(const MCSection *Section) {
157 assert(Section && "Cannot switch to a null section!");
158
159 CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
160 }
161
EmitInstruction(const MCInst & Inst)162 void 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
EmitInstToFragment(const MCInst & Inst)195 void 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
EmitDwarfAdvanceLineAddr(int64_t LineDelta,const MCSymbol * LastLabel,const MCSymbol * Label,unsigned PointerSize)205 void 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
EmitDwarfAdvanceFrameAddr(const MCSymbol * LastLabel,const MCSymbol * Label)223 void 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
EmitValueToOffset(const MCExpr * Offset,unsigned char Value)235 bool 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
EmitGPRel32Value(const MCExpr * Value)258 void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) {
259 MCDataFragment *DF = getOrCreateDataFragment();
260
261 DF->addFixup(MCFixup::Create(DF->getContents().size(),
262 Value,
263 FK_GPRel_4));
264 DF->getContents().resize(DF->getContents().size() + 4, 0);
265 }
266
FinishImpl()267 void MCObjectStreamer::FinishImpl() {
268 // Dump out the dwarf file & directory tables and line tables.
269 const MCSymbol *LineSectionSymbol = NULL;
270 if (getContext().hasDwarfFiles())
271 LineSectionSymbol = MCDwarfFileTable::Emit(this);
272
273 // If we are generating dwarf for assembly source files dump out the sections.
274 if (getContext().getGenDwarfForAssembly())
275 MCGenDwarfInfo::Emit(this, LineSectionSymbol);
276
277 getAssembler().Finish();
278 }
279