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 using namespace llvm;
22
MCObjectStreamer(MCContext & Context,TargetAsmBackend & TAB,raw_ostream & OS,MCCodeEmitter * Emitter_)23 MCObjectStreamer::MCObjectStreamer(MCContext &Context, TargetAsmBackend &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,TargetAsmBackend & TAB,raw_ostream & OS,MCCodeEmitter * Emitter_,MCAssembler * _Assembler)33 MCObjectStreamer::MCObjectStreamer(MCContext &Context, TargetAsmBackend &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
EmitLabel(MCSymbol * Symbol)108 void 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
EmitULEB128Value(const MCExpr * Value)123 void 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
EmitSLEB128Value(const MCExpr * Value)133 void 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
EmitWeakReference(MCSymbol * Alias,const MCSymbol * Symbol)143 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
144 const MCSymbol *Symbol) {
145 report_fatal_error("This file format doesn't support weak aliases.");
146 }
147
ChangeSection(const MCSection * Section)148 void MCObjectStreamer::ChangeSection(const MCSection *Section) {
149 assert(Section && "Cannot switch to a null section!");
150
151 CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
152 }
153
EmitInstruction(const MCInst & Inst)154 void 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
EmitInstToFragment(const MCInst & Inst)187 void 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
EmitDwarfAdvanceLineAddr(int64_t LineDelta,const MCSymbol * LastLabel,const MCSymbol * Label,unsigned PointerSize)197 void 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
EmitDwarfAdvanceFrameAddr(const MCSymbol * LastLabel,const MCSymbol * Label)215 void 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
EmitValueToOffset(const MCExpr * Offset,unsigned char Value)227 void 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
Finish()248 void 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