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::EmitLabel(MCSymbol *Symbol) {
80 assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
81 assert(CurSection && "Cannot emit before setting section!");
83 Symbol->setSection(*CurSection);
85 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
87 // FIXME: This is wasteful, we don't necessarily need to create a data
88 // fragment. Instead, we should mark the symbol as pointing into the data
89 // fragment if it exists, otherwise we should just queue the label and set its
90 // fragment pointer when we emit the next fragment.
91 MCDataFragment *F = getOrCreateDataFragment();
92 assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
94 SD.setOffset(F->getContents().size());
97 void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value,
99 new MCLEBFragment(*Value, false, getCurrentSectionData());
102 void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value,
103 unsigned AddrSpace) {
104 new MCLEBFragment(*Value, true, getCurrentSectionData());
107 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
108 const MCSymbol *Symbol) {
109 report_fatal_error("This file format doesn't support weak aliases.");
112 void MCObjectStreamer::SwitchSection(const MCSection *Section) {
113 assert(Section && "Cannot switch to a null section!");
115 // If already in this section, then this is a noop.
116 if (Section == CurSection) return;
118 PrevSection = CurSection;
119 CurSection = Section;
120 CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
123 void MCObjectStreamer::EmitInstruction(const MCInst &Inst) {
125 for (unsigned i = Inst.getNumOperands(); i--; )
126 if (Inst.getOperand(i).isExpr())
127 AddValueSymbols(Inst.getOperand(i).getExpr());
129 getCurrentSectionData()->setHasInstructions(true);
131 // Now that a machine instruction has been assembled into this section, make
132 // a line entry for any .loc directive that has been seen.
133 MCLineEntry::Make(this, getCurrentSection());
135 // If this instruction doesn't need relaxation, just emit it as data.
136 if (!getAssembler().getBackend().MayNeedRelaxation(Inst)) {
137 EmitInstToData(Inst);
141 // Otherwise, if we are relaxing everything, relax the instruction as much as
142 // possible and emit it as data.
143 if (getAssembler().getRelaxAll()) {
145 getAssembler().getBackend().RelaxInstruction(Inst, Relaxed);
146 while (getAssembler().getBackend().MayNeedRelaxation(Relaxed))
147 getAssembler().getBackend().RelaxInstruction(Relaxed, Relaxed);
148 EmitInstToData(Relaxed);
152 // Otherwise emit to a separate fragment.
153 EmitInstToFragment(Inst);
156 void MCObjectStreamer::Finish() {
157 getAssembler().Finish();