1 //===- lib/MC/MCObjectStreamer.cpp - Object File MCStreamer Interface -----===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/MC/MCAsmInfo.h"
11 #include "llvm/MC/MCObjectStreamer.h"
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"
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),
34 MCObjectStreamer::~MCObjectStreamer() {
35 delete &Assembler->getBackend();
36 delete &Assembler->getEmitter();
37 delete &Assembler->getWriter();
41 MCFragment *MCObjectStreamer::getCurrentFragment() const {
42 assert(getCurrentSectionData() && "No current section!");
44 if (!getCurrentSectionData()->empty())
45 return &getCurrentSectionData()->getFragmentList().back();
50 MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() const {
51 MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
53 F = new MCDataFragment(getCurrentSectionData());
57 const MCExpr *MCObjectStreamer::AddValueSymbols(const MCExpr *Value) {
58 switch (Value->getKind()) {
60 cast<MCTargetExpr>(Value)->AddValueSymbols(Assembler);
63 case MCExpr::Constant:
66 case MCExpr::Binary: {
67 const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
68 AddValueSymbols(BE->getLHS());
69 AddValueSymbols(BE->getRHS());
73 case MCExpr::SymbolRef:
74 Assembler->getOrCreateSymbolData(cast<MCSymbolRefExpr>(Value)->getSymbol());
78 AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
85 void MCObjectStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
86 bool isPCRel, unsigned AddrSpace) {
87 assert(AddrSpace == 0 && "Address space must be 0!");
88 MCDataFragment *DF = getOrCreateDataFragment();
90 // Avoid fixups when possible.
92 if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue, getAssembler())) {
93 EmitIntValue(AbsValue, Size, AddrSpace);
96 DF->addFixup(MCFixup::Create(DF->getContents().size(),
98 MCFixup::getKindForSize(Size, isPCRel)));
99 DF->getContents().resize(DF->getContents().size() + Size, 0);
102 void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
103 assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
104 assert(getCurrentSection() && "Cannot emit before setting section!");
106 Symbol->setSection(*getCurrentSection());
108 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
110 // FIXME: This is wasteful, we don't necessarily need to create a data
111 // fragment. Instead, we should mark the symbol as pointing into the data
112 // fragment if it exists, otherwise we should just queue the label and set its
113 // fragment pointer when we emit the next fragment.
114 MCDataFragment *F = getOrCreateDataFragment();
115 assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
117 SD.setOffset(F->getContents().size());
120 void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value,
121 unsigned AddrSpace) {
123 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
124 EmitULEB128IntValue(IntValue, AddrSpace);
127 new MCLEBFragment(*Value, false, getCurrentSectionData());
130 void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value,
131 unsigned AddrSpace) {
133 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
134 EmitSLEB128IntValue(IntValue, AddrSpace);
137 new MCLEBFragment(*Value, true, getCurrentSectionData());
140 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
141 const MCSymbol *Symbol) {
142 report_fatal_error("This file format doesn't support weak aliases.");
145 void MCObjectStreamer::ChangeSection(const MCSection *Section) {
146 assert(Section && "Cannot switch to a null section!");
148 CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
151 void MCObjectStreamer::EmitInstruction(const MCInst &Inst) {
153 for (unsigned i = Inst.getNumOperands(); i--; )
154 if (Inst.getOperand(i).isExpr())
155 AddValueSymbols(Inst.getOperand(i).getExpr());
157 getCurrentSectionData()->setHasInstructions(true);
159 // Now that a machine instruction has been assembled into this section, make
160 // a line entry for any .loc directive that has been seen.
161 MCLineEntry::Make(this, getCurrentSection());
163 // If this instruction doesn't need relaxation, just emit it as data.
164 if (!getAssembler().getBackend().MayNeedRelaxation(Inst)) {
165 EmitInstToData(Inst);
169 // Otherwise, if we are relaxing everything, relax the instruction as much as
170 // possible and emit it as data.
171 if (getAssembler().getRelaxAll()) {
173 getAssembler().getBackend().RelaxInstruction(Inst, Relaxed);
174 while (getAssembler().getBackend().MayNeedRelaxation(Relaxed))
175 getAssembler().getBackend().RelaxInstruction(Relaxed, Relaxed);
176 EmitInstToData(Relaxed);
180 // Otherwise emit to a separate fragment.
181 EmitInstToFragment(Inst);
184 void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst) {
185 MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
187 raw_svector_ostream VecOS(IF->getCode());
188 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups());
191 static const MCExpr *BuildSymbolDiff(MCContext &Context,
192 const MCSymbol *A, const MCSymbol *B) {
193 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
195 MCSymbolRefExpr::Create(A, Variant, Context);
197 MCSymbolRefExpr::Create(B, Variant, Context);
198 const MCExpr *AddrDelta =
199 MCBinaryExpr::Create(MCBinaryExpr::Sub, ARef, BRef, Context);
203 static const MCExpr *ForceExpAbs(MCObjectStreamer *Streamer,
204 MCContext &Context, const MCExpr* Expr) {
205 if (Context.getAsmInfo().hasAggressiveSymbolFolding())
208 MCSymbol *ABS = Context.CreateTempSymbol();
209 Streamer->EmitAssignment(ABS, Expr);
210 return MCSymbolRefExpr::Create(ABS, Context);
213 void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
214 const MCSymbol *LastLabel,
215 const MCSymbol *Label) {
217 int PointerSize = getContext().getTargetAsmInfo().getPointerSize();
218 EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
221 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
223 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
224 MCDwarfLineAddr::Emit(this, LineDelta, Res);
227 AddrDelta = ForceExpAbs(this, getContext(), AddrDelta);
228 new MCDwarfLineAddrFragment(LineDelta, *AddrDelta, getCurrentSectionData());
231 void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
232 const MCSymbol *Label) {
233 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
235 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
236 MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
239 AddrDelta = ForceExpAbs(this, getContext(), AddrDelta);
240 new MCDwarfCallFrameFragment(*AddrDelta, getCurrentSectionData());
243 void MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
244 unsigned char Value) {
246 if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
247 new MCOrgFragment(*Offset, Value, getCurrentSectionData());
251 MCSymbol *CurrentPos = getContext().CreateTempSymbol();
252 EmitLabel(CurrentPos);
253 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
255 MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
256 const MCExpr *Delta =
257 MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
259 if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
260 report_fatal_error("expected assembly-time absolute expression");
261 EmitFill(Res, Value, 0);
264 void MCObjectStreamer::Finish() {
265 // Dump out the dwarf file & directory tables and line tables.
266 if (getContext().hasDwarfFiles())
267 MCDwarfFileTable::Emit(this);
269 getAssembler().Finish();