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//===- lib/MC/MCObjectStreamer.cpp - Object File MCStreamer Interface -----===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCObjectStreamer.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Target/TargetAsmBackend.h"
using namespace llvm;
MCObjectStreamer::MCObjectStreamer(MCContext &Context, TargetAsmBackend &TAB,
raw_ostream &_OS, MCCodeEmitter *_Emitter,
bool _PadSectionToAlignment)
: MCStreamer(Context), Assembler(new MCAssembler(Context, TAB,
*_Emitter,
_PadSectionToAlignment,
_OS)),
CurSectionData(0)
{
}
MCObjectStreamer::~MCObjectStreamer() {
delete &Assembler->getBackend();
delete &Assembler->getEmitter();
delete Assembler;
}
MCFragment *MCObjectStreamer::getCurrentFragment() const {
assert(getCurrentSectionData() && "No current section!");
if (!getCurrentSectionData()->empty())
return &getCurrentSectionData()->getFragmentList().back();
return 0;
}
MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() const {
MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
if (!F)
F = new MCDataFragment(getCurrentSectionData());
return F;
}
const MCExpr *MCObjectStreamer::AddValueSymbols(const MCExpr *Value) {
switch (Value->getKind()) {
case MCExpr::Target: llvm_unreachable("Can't handle target exprs yet!");
case MCExpr::Constant:
break;
case MCExpr::Binary: {
const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
AddValueSymbols(BE->getLHS());
AddValueSymbols(BE->getRHS());
break;
}
case MCExpr::SymbolRef:
Assembler->getOrCreateSymbolData(cast<MCSymbolRefExpr>(Value)->getSymbol());
break;
case MCExpr::Unary:
AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
break;
}
return Value;
}
void MCObjectStreamer::EmitValue(const MCExpr *Value, unsigned Size,
unsigned AddrSpace, bool UseSet) {
assert(AddrSpace == 0 && "Address space must be 0!");
MCDataFragment *DF = getOrCreateDataFragment();
// Avoid fixups when possible.
int64_t AbsValue;
if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
// FIXME: Endianness assumption.
for (unsigned i = 0; i != Size; ++i)
DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
} else {
DF->addFixup(MCFixup::Create(DF->getContents().size(),
AddValueSymbols(Value),
MCFixup::getKindForSize(Size, false)));
DF->getContents().resize(DF->getContents().size() + Size, 0);
}
}
void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
assert(CurSection && "Cannot emit before setting section!");
Symbol->setSection(*CurSection);
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
// FIXME: This is wasteful, we don't necessarily need to create a data
// fragment. Instead, we should mark the symbol as pointing into the data
// fragment if it exists, otherwise we should just queue the label and set its
// fragment pointer when we emit the next fragment.
MCDataFragment *F = getOrCreateDataFragment();
assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
SD.setFragment(F);
SD.setOffset(F->getContents().size());
}
void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value,
unsigned AddrSpace) {
new MCLEBFragment(*Value, false, getCurrentSectionData());
}
void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value,
unsigned AddrSpace) {
new MCLEBFragment(*Value, true, getCurrentSectionData());
}
void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
const MCSymbol *Symbol) {
report_fatal_error("This file format doesn't support weak aliases.");
}
void MCObjectStreamer::SwitchSection(const MCSection *Section) {
assert(Section && "Cannot switch to a null section!");
// If already in this section, then this is a noop.
if (Section == CurSection) return;
PrevSection = CurSection;
CurSection = Section;
CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
}
void MCObjectStreamer::EmitInstruction(const MCInst &Inst) {
// Scan for values.
for (unsigned i = Inst.getNumOperands(); i--; )
if (Inst.getOperand(i).isExpr())
AddValueSymbols(Inst.getOperand(i).getExpr());
getCurrentSectionData()->setHasInstructions(true);
// Now that a machine instruction has been assembled into this section, make
// a line entry for any .loc directive that has been seen.
MCLineEntry::Make(this, getCurrentSection());
// If this instruction doesn't need relaxation, just emit it as data.
if (!getAssembler().getBackend().MayNeedRelaxation(Inst)) {
EmitInstToData(Inst);
return;
}
// Otherwise, if we are relaxing everything, relax the instruction as much as
// possible and emit it as data.
if (getAssembler().getRelaxAll()) {
MCInst Relaxed;
getAssembler().getBackend().RelaxInstruction(Inst, Relaxed);
while (getAssembler().getBackend().MayNeedRelaxation(Relaxed))
getAssembler().getBackend().RelaxInstruction(Relaxed, Relaxed);
EmitInstToData(Relaxed);
return;
}
// Otherwise emit to a separate fragment.
EmitInstToFragment(Inst);
}
void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst) {
MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
raw_svector_ostream VecOS(IF->getCode());
getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups());
}
void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
const MCSymbol *LastLabel,
const MCSymbol *Label) {
if (!LastLabel) {
int PointerSize = getAssembler().getBackend().getPointerSize();
EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
return;
}
MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
const MCExpr *LabelRef =
MCSymbolRefExpr::Create(Label, Variant, getContext());
const MCExpr *LastLabelRef =
MCSymbolRefExpr::Create(LastLabel, Variant, getContext());
const MCExpr *AddrDelta =
MCBinaryExpr::Create(MCBinaryExpr::Sub, LabelRef, LastLabelRef,
getContext());
int64_t Res;
if (AddrDelta->EvaluateAsAbsolute(Res, &getAssembler())) {
MCDwarfLineAddr::Emit(this, LineDelta, Res);
return;
}
new MCDwarfLineAddrFragment(LineDelta, *AddrDelta, getCurrentSectionData());
}
void MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
unsigned char Value) {
new MCOrgFragment(*Offset, Value, getCurrentSectionData());
}
void MCObjectStreamer::Finish() {
getAssembler().Finish();
}
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