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/MCObjectStreamer.h"
12 #include "llvm/Support/ErrorHandling.h"
13 #include "llvm/MC/MCAssembler.h"
14 #include "llvm/MC/MCCodeEmitter.h"
15 #include "llvm/MC/MCDwarf.h"
16 #include "llvm/MC/MCExpr.h"
17 #include "llvm/MC/MCSymbol.h"
18 #include "llvm/Target/TargetAsmBackend.h"
21 MCObjectStreamer::MCObjectStreamer(MCContext &Context, TargetAsmBackend &TAB,
22 raw_ostream &_OS, MCCodeEmitter *_Emitter,
23 bool _PadSectionToAlignment)
24 : MCStreamer(Context), Assembler(new MCAssembler(Context, TAB,
26 _PadSectionToAlignment,
32 MCObjectStreamer::~MCObjectStreamer() {
33 delete &Assembler->getBackend();
34 delete &Assembler->getEmitter();
38 MCFragment *MCObjectStreamer::getCurrentFragment() const {
39 assert(getCurrentSectionData() && "No current section!");
41 if (!getCurrentSectionData()->empty())
42 return &getCurrentSectionData()->getFragmentList().back();
47 MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() const {
48 MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
50 F = new MCDataFragment(getCurrentSectionData());
54 const MCExpr *MCObjectStreamer::AddValueSymbols(const MCExpr *Value) {
55 switch (Value->getKind()) {
56 case MCExpr::Target: llvm_unreachable("Can't handle target exprs yet!");
57 case MCExpr::Constant:
60 case MCExpr::Binary: {
61 const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
62 AddValueSymbols(BE->getLHS());
63 AddValueSymbols(BE->getRHS());
67 case MCExpr::SymbolRef:
68 Assembler->getOrCreateSymbolData(cast<MCSymbolRefExpr>(Value)->getSymbol());
72 AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
79 void MCObjectStreamer::EmitValue(const MCExpr *Value, unsigned Size,
80 unsigned AddrSpace, bool UseSet) {
81 assert(AddrSpace == 0 && "Address space must be 0!");
82 MCDataFragment *DF = getOrCreateDataFragment();
84 // Avoid fixups when possible.
86 if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
87 // FIXME: Endianness assumption.
88 for (unsigned i = 0; i != Size; ++i)
89 DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
91 DF->addFixup(MCFixup::Create(DF->getContents().size(),
92 AddValueSymbols(Value),
93 MCFixup::getKindForSize(Size, false)));
94 DF->getContents().resize(DF->getContents().size() + Size, 0);
98 void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
99 assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
100 assert(CurSection && "Cannot emit before setting section!");
102 Symbol->setSection(*CurSection);
104 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
106 // FIXME: This is wasteful, we don't necessarily need to create a data
107 // fragment. Instead, we should mark the symbol as pointing into the data
108 // fragment if it exists, otherwise we should just queue the label and set its
109 // fragment pointer when we emit the next fragment.
110 MCDataFragment *F = getOrCreateDataFragment();
111 assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
113 SD.setOffset(F->getContents().size());
116 void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value,
117 unsigned AddrSpace) {
119 if (Value->EvaluateAsAbsolute(IntValue, &getAssembler())) {
120 EmitULEB128IntValue(IntValue, AddrSpace);
123 new MCLEBFragment(*Value, false, getCurrentSectionData());
126 void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value,
127 unsigned AddrSpace) {
129 if (Value->EvaluateAsAbsolute(IntValue, &getAssembler())) {
130 EmitSLEB128IntValue(IntValue, AddrSpace);
133 new MCLEBFragment(*Value, true, getCurrentSectionData());
136 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
137 const MCSymbol *Symbol) {
138 report_fatal_error("This file format doesn't support weak aliases.");
141 void MCObjectStreamer::SwitchSection(const MCSection *Section) {
142 assert(Section && "Cannot switch to a null section!");
144 // If already in this section, then this is a noop.
145 if (Section == CurSection) return;
147 PrevSection = CurSection;
148 CurSection = Section;
149 CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
152 void MCObjectStreamer::EmitInstruction(const MCInst &Inst) {
154 for (unsigned i = Inst.getNumOperands(); i--; )
155 if (Inst.getOperand(i).isExpr())
156 AddValueSymbols(Inst.getOperand(i).getExpr());
158 getCurrentSectionData()->setHasInstructions(true);
160 // Now that a machine instruction has been assembled into this section, make
161 // a line entry for any .loc directive that has been seen.
162 MCLineEntry::Make(this, getCurrentSection());
164 // If this instruction doesn't need relaxation, just emit it as data.
165 if (!getAssembler().getBackend().MayNeedRelaxation(Inst)) {
166 EmitInstToData(Inst);
170 // Otherwise, if we are relaxing everything, relax the instruction as much as
171 // possible and emit it as data.
172 if (getAssembler().getRelaxAll()) {
174 getAssembler().getBackend().RelaxInstruction(Inst, Relaxed);
175 while (getAssembler().getBackend().MayNeedRelaxation(Relaxed))
176 getAssembler().getBackend().RelaxInstruction(Relaxed, Relaxed);
177 EmitInstToData(Relaxed);
181 // Otherwise emit to a separate fragment.
182 EmitInstToFragment(Inst);
185 void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst) {
186 MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
188 raw_svector_ostream VecOS(IF->getCode());
189 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups());
192 void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
193 const MCSymbol *LastLabel,
194 const MCSymbol *Label) {
196 int PointerSize = getAssembler().getBackend().getPointerSize();
197 EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
200 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
201 const MCExpr *LabelRef =
202 MCSymbolRefExpr::Create(Label, Variant, getContext());
203 const MCExpr *LastLabelRef =
204 MCSymbolRefExpr::Create(LastLabel, Variant, getContext());
205 const MCExpr *AddrDelta =
206 MCBinaryExpr::Create(MCBinaryExpr::Sub, LabelRef, LastLabelRef,
209 if (AddrDelta->EvaluateAsAbsolute(Res, &getAssembler())) {
210 MCDwarfLineAddr::Emit(this, LineDelta, Res);
213 new MCDwarfLineAddrFragment(LineDelta, *AddrDelta, getCurrentSectionData());
216 void MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
217 unsigned char Value) {
218 new MCOrgFragment(*Offset, Value, getCurrentSectionData());
221 void MCObjectStreamer::Finish() {
222 getAssembler().Finish();