#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSymbol.h"
+#include "llvm/MC/MCValue.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/ErrorHandling.h"
namespace {
+static void SetBinding(MCSymbolData &SD, unsigned Binding) {
+ assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
+ Binding == ELF::STB_WEAK);
+ uint32_t OtherFlags = SD.getFlags() & ~(0xf << ELF_STB_Shift);
+ SD.setFlags(OtherFlags | (Binding << ELF_STB_Shift));
+}
+
+static unsigned GetBinding(const MCSymbolData &SD) {
+ uint32_t Binding = (SD.getFlags() & (0xf << ELF_STB_Shift)) >> ELF_STB_Shift;
+ assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
+ Binding == ELF::STB_WEAK);
+ return Binding;
+}
+
+static void SetType(MCSymbolData &SD, unsigned Type) {
+ assert(Type == ELF::STT_NOTYPE || Type == ELF::STT_OBJECT ||
+ Type == ELF::STT_FUNC || Type == ELF::STT_SECTION ||
+ Type == ELF::STT_FILE || Type == ELF::STT_COMMON ||
+ Type == ELF::STT_TLS);
+
+ uint32_t OtherFlags = SD.getFlags() & ~(0xf << ELF_STT_Shift);
+ SD.setFlags(OtherFlags | (Type << ELF_STT_Shift));
+}
+
+static void SetVisibility(MCSymbolData &SD, unsigned Visibility) {
+ assert(Visibility == ELF::STV_DEFAULT || Visibility == ELF::STV_INTERNAL ||
+ Visibility == ELF::STV_HIDDEN || Visibility == ELF::STV_PROTECTED);
+
+ uint32_t OtherFlags = SD.getFlags() & ~(0xf << ELF_STV_Shift);
+ SD.setFlags(OtherFlags | (Visibility << ELF_STV_Shift));
+}
+
class MCELFStreamer : public MCObjectStreamer {
- void EmitInstToFragment(const MCInst &Inst);
- void EmitInstToData(const MCInst &Inst);
public:
MCELFStreamer(MCContext &Context, TargetAsmBackend &TAB,
raw_ostream &OS, MCCodeEmitter *Emitter)
virtual void InitSections();
virtual void EmitLabel(MCSymbol *Symbol);
virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
+ virtual void EmitThumbFunc(MCSymbol *Func);
virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
+ virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol);
+ virtual void SwitchSection(const MCSection *Section);
virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
assert(0 && "ELF doesn't support this directive");
DEBUG(dbgs() << "FIXME: MCELFStreamer:EmitDwarfFileDirective not implemented\n");
}
- virtual void EmitInstruction(const MCInst &Inst);
virtual void Finish();
private:
+ virtual void EmitInstToFragment(const MCInst &Inst);
+ virtual void EmitInstToData(const MCInst &Inst);
+
+ struct LocalCommon {
+ MCSymbolData *SD;
+ uint64_t Size;
+ unsigned ByteAlignment;
+ };
+ std::vector<LocalCommon> LocalCommons;
+
SmallPtrSet<MCSymbol *, 16> BindingExplicitlySet;
/// @}
void SetSection(StringRef Section, unsigned Type, unsigned Flags,
SetSectionText();
}
-static bool isSymbolLinkerVisible(const MCAssembler &Asm,
- const MCSymbolData &Data) {
- const MCSymbol &Symbol = Data.getSymbol();
- // Absolute temporary labels are never visible.
- if (!Symbol.isInSection())
- return false;
-
- if (Asm.getBackend().doesSectionRequireSymbols(Symbol.getSection()))
- return true;
-
- if (!Data.isExternal())
- return false;
-
- return Asm.isSymbolLinkerVisible(Symbol);
-}
-
void MCELFStreamer::EmitLabel(MCSymbol *Symbol) {
assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
- // We have to create a new fragment if this is an atom defining symbol,
- // fragments cannot span atoms.
- if (isSymbolLinkerVisible(getAssembler(), SD))
- new MCDataFragment(getCurrentSectionData());
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF&>(Symbol->getSection());
+ if (Section.getFlags() & MCSectionELF::SHF_TLS)
+ SetType(SD, ELF::STT_TLS);
// 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
void MCELFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
switch (Flag) {
+ case MCAF_SyntaxUnified: return; // no-op here.
+ case MCAF_Code16: return; // no-op here.
+ case MCAF_Code32: return; // no-op here.
case MCAF_SubsectionsViaSymbols:
getAssembler().setSubsectionsViaSymbols(true);
return;
assert(0 && "invalid assembler flag!");
}
+void MCELFStreamer::EmitThumbFunc(MCSymbol *Func) {
+ // FIXME: Anything needed here to flag the function as thumb?
+}
+
void MCELFStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
// TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
// MCObjectStreamer.
Symbol->setVariableValue(AddValueSymbols(Value));
}
-static void SetBinding(MCSymbolData &SD, unsigned Binding) {
- assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
- Binding == ELF::STB_WEAK);
- uint32_t OtherFlags = SD.getFlags() & ~(0xf << ELF_STB_Shift);
- SD.setFlags(OtherFlags | (Binding << ELF_STB_Shift));
-}
+// This is a hack. To be able to implement weakrefs the writer has to be able
+// to distinguish
+// .weakref foo, bar
+// .long foo
+// from
+// .weakref foo, bar
+// .long bar
+// since the first case should produce a weak undefined reference and the second
+// one a strong one.
+// If we created foo as a regular alias pointing to bar (foo = bar), then
+// MCExpr::EvaluateAsRelocatable would recurse on foo and the writer would
+// never see it used in a relocation.
+// What we do is create a MCTargetExpr that when evaluated produces a symbol
+// ref to a temporary symbol. This temporary symbol in turn is a variable
+// that equals the original symbol (tmp = bar). With this hack the writer
+// gets a relocation with tmp and can correctly implement weak references.
-static unsigned GetBinding(const MCSymbolData &SD) {
- uint32_t Binding = (SD.getFlags() & (0xf << ELF_STB_Shift)) >> ELF_STB_Shift;
- assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
- Binding == ELF::STB_WEAK);
- return Binding;
-}
+namespace {
+class WeakRefExpr : public MCTargetExpr {
+private:
+ const MCSymbolRefExpr *Alias;
-static void SetType(MCSymbolData &SD, unsigned Type) {
- assert(Type == ELF::STT_NOTYPE || Type == ELF::STT_OBJECT ||
- Type == ELF::STT_FUNC || Type == ELF::STT_SECTION ||
- Type == ELF::STT_FILE || Type == ELF::STT_COMMON ||
- Type == ELF::STT_TLS);
+ explicit WeakRefExpr(const MCSymbolRefExpr *Alias_)
+ : MCTargetExpr(), Alias(Alias_) {}
- uint32_t OtherFlags = SD.getFlags() & ~(0xf << ELF_STT_Shift);
- SD.setFlags(OtherFlags | (Type << ELF_STT_Shift));
+public:
+ virtual void PrintImpl(raw_ostream &OS) const {
+ llvm_unreachable("Unimplemented");
+ }
+
+ virtual bool EvaluateAsRelocatableImpl(MCValue &Res,
+ const MCAsmLayout *Layout) const {
+ Res = MCValue::get(Alias, 0, 0);
+ return true;
+ }
+
+ static const WeakRefExpr *Create(const MCSymbol *Alias, MCContext &Ctx) {
+ const MCSymbolRefExpr *A = MCSymbolRefExpr::Create(Alias, Ctx);
+ return new (Ctx) WeakRefExpr(A);
+ }
+};
+} // end anonymous namespace
+
+void MCELFStreamer::SwitchSection(const MCSection *Section) {
+ const MCSymbol *Grp = static_cast<const MCSectionELF *>(Section)->getGroup();
+ if (Grp)
+ getAssembler().getOrCreateSymbolData(*Grp);
+ this->MCObjectStreamer::SwitchSection(Section);
}
-static void SetVisibility(MCSymbolData &SD, unsigned Visibility) {
- assert(Visibility == ELF::STV_DEFAULT || Visibility == ELF::STV_INTERNAL ||
- Visibility == ELF::STV_HIDDEN || Visibility == ELF::STV_PROTECTED);
+void MCELFStreamer::EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {
+ getAssembler().getOrCreateSymbolData(*Symbol);
+ MCSymbolData &AliasSD = getAssembler().getOrCreateSymbolData(*Alias);
+ AliasSD.setFlags(AliasSD.getFlags() | ELF_Other_Weakref);
- uint32_t OtherFlags = SD.getFlags() & ~(0xf << ELF_STV_Shift);
- SD.setFlags(OtherFlags | (Visibility << ELF_STV_Shift));
+ // Create the alias that actually points to Symbol
+ const MCSymbolRefExpr *SymRef = MCSymbolRefExpr::Create(Symbol, getContext());
+ MCSymbol *RealAlias = getContext().CreateTempSymbol();
+ RealAlias->setVariableValue(SymRef);
+
+ MCSymbolData &RealAliasSD = getAssembler().getOrCreateSymbolData(*RealAlias);
+ RealAliasSD.setFlags(RealAliasSD.getFlags() | ELF_Other_Weakref);
+
+ const MCExpr *Value = WeakRefExpr::Create(RealAlias, getContext());
+ Alias->setVariableValue(Value);
}
void MCELFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
assert(0 && "Invalid symbol attribute for ELF!");
break;
+ case MCSA_ELF_TypeGnuUniqueObject:
+ // Ignore for now.
+ break;
+
case MCSA_Global:
SetBinding(SD, ELF::STB_GLOBAL);
SD.setExternal(true);
case MCSA_WeakReference:
case MCSA_Weak:
SetBinding(SD, ELF::STB_WEAK);
+ SD.setExternal(true);
BindingExplicitlySet.insert(Symbol);
break;
MCSectionELF::SHF_WRITE |
MCSectionELF::SHF_ALLOC,
SectionKind::getBSS());
-
- MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
- new MCAlignFragment(ByteAlignment, 0, 1, ByteAlignment, &SectData);
-
- MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
- SD.setFragment(F);
Symbol->setSection(*Section);
- // Update the maximum alignment of the section if necessary.
- if (ByteAlignment > SectData.getAlignment())
- SectData.setAlignment(ByteAlignment);
+ struct LocalCommon L = {&SD, Size, ByteAlignment};
+ LocalCommons.push_back(L);
} else {
SD.setCommon(Size, ByteAlignment);
}
DF->getContents().append(Code.begin(), Code.end());
}
-void MCELFStreamer::EmitInstruction(const MCInst &Inst) {
- // Scan for values.
- for (unsigned i = 0; i != Inst.getNumOperands(); ++i)
- if (Inst.getOperand(i).isExpr())
- AddValueSymbols(Inst.getOperand(i).getExpr());
-
- getCurrentSectionData()->setHasInstructions(true);
-
- // If this instruction doesn't need relaxation, just emit it as data.
- if (!getAssembler().getBackend().MayNeedRelaxation(Inst)) {
- EmitInstToData(Inst);
- return;
+void MCELFStreamer::Finish() {
+ // FIXME: duplicated code with the MachO streamer.
+ // Dump out the dwarf file & directory tables and line tables.
+ if (getContext().hasDwarfFiles()) {
+ const MCSection *DwarfLineSection =
+ getContext().getELFSection(".debug_line", 0, 0,
+ SectionKind::getDataRelLocal());
+ MCDwarfFileTable::Emit(this, DwarfLineSection);
}
- // 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;
- }
+ for (std::vector<LocalCommon>::const_iterator i = LocalCommons.begin(),
+ e = LocalCommons.end();
+ i != e; ++i) {
+ MCSymbolData *SD = i->SD;
+ uint64_t Size = i->Size;
+ unsigned ByteAlignment = i->ByteAlignment;
+ const MCSymbol &Symbol = SD->getSymbol();
+ const MCSection &Section = Symbol.getSection();
- // Otherwise emit to a separate fragment.
- EmitInstToFragment(Inst);
-}
+ MCSectionData &SectData = getAssembler().getOrCreateSectionData(Section);
+ new MCAlignFragment(ByteAlignment, 0, 1, ByteAlignment, &SectData);
-void MCELFStreamer::Finish() {
- // FIXME: We create more atoms than it is necessary. Some relocations to
- // merge sections can be implemented with section address + offset,
- // figure out which ones and why.
-
- // First, scan the symbol table to build a lookup table from fragments to
- // defining symbols.
- DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
- for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
- ie = getAssembler().symbol_end(); it != ie; ++it) {
- if (isSymbolLinkerVisible(getAssembler(), *it) &&
- it->getFragment()) {
- // An atom defining symbol should never be internal to a fragment.
- assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
- DefiningSymbolMap[it->getFragment()] = it;
- }
- }
+ MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
+ SD->setFragment(F);
- // Set the fragment atom associations by tracking the last seen atom defining
- // symbol.
- for (MCAssembler::iterator it = getAssembler().begin(),
- ie = getAssembler().end(); it != ie; ++it) {
- MCSymbolData *CurrentAtom = 0;
- for (MCSectionData::iterator it2 = it->begin(),
- ie2 = it->end(); it2 != ie2; ++it2) {
- if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
- CurrentAtom = SD;
- it2->setAtom(CurrentAtom);
- }
+ // Update the maximum alignment of the section if necessary.
+ if (ByteAlignment > SectData.getAlignment())
+ SectData.setAlignment(ByteAlignment);
}
this->MCObjectStreamer::Finish();
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