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-rw-r--r--llvm/lib/MC/ELFObjectWriter.cpp15
-rw-r--r--llvm/lib/MC/MCAssembler.cpp1
-rw-r--r--llvm/lib/MC/MCContext.cpp50
-rw-r--r--llvm/lib/MC/MCELFStreamer.cpp4
-rw-r--r--llvm/lib/MC/MCMachOStreamer.cpp2
-rw-r--r--llvm/lib/MC/MCObjectStreamer.cpp30
-rw-r--r--llvm/lib/MC/MCSection.cpp3
-rw-r--r--llvm/lib/MC/MCStreamer.cpp21
-rw-r--r--llvm/lib/MC/MCXCOFFStreamer.cpp14
9 files changed, 63 insertions, 77 deletions
diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index 6099bb8..ae8dffc 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -559,20 +559,7 @@ void ELFWriter::computeSymbolTable(const RevGroupMapTy &RevGroupMap) {
} else {
const MCSectionELF &Section =
static_cast<const MCSectionELF &>(Symbol.getSection());
-
- // We may end up with a situation when section symbol is technically
- // defined, but should not be. That happens because we explicitly
- // pre-create few .debug_* sections to have accessors.
- // And if these sections were not really defined in the code, but were
- // referenced, we simply error out.
- if (!Section.isRegistered()) {
- assert(static_cast<const MCSymbolELF &>(Symbol).getType() ==
- ELF::STT_SECTION);
- Ctx.reportError(SMLoc(),
- "Undefined section reference: " + Symbol.getName());
- continue;
- }
-
+ assert(Section.isRegistered());
if (Mode == NonDwoOnly && isDwoSection(Section))
continue;
MSD.SectionIndex = Section.getOrdinal();
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
index e142ac1..8500fd1 100644
--- a/llvm/lib/MC/MCAssembler.cpp
+++ b/llvm/lib/MC/MCAssembler.cpp
@@ -106,7 +106,6 @@ void MCAssembler::reset() {
bool MCAssembler::registerSection(MCSection &Section) {
if (Section.isRegistered())
return false;
- assert(Section.curFragList()->Head && "allocInitialFragment not called");
Sections.push_back(&Section);
Section.setIsRegistered(true);
return true;
diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index cf1ef31..39bf628 100644
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/lib/MC/MCContext.cpp
@@ -200,16 +200,6 @@ MCInst *MCContext::createMCInst() {
return new (MCInstAllocator.Allocate()) MCInst;
}
-// Allocate the initial MCFragment for the begin symbol.
-MCFragment *MCContext::allocInitialFragment(MCSection &Sec) {
- assert(!Sec.curFragList()->Head);
- auto *F = allocFragment<MCFragment>();
- F->setParent(&Sec);
- Sec.curFragList()->Head = F;
- Sec.curFragList()->Tail = F;
- return F;
-}
-
//===----------------------------------------------------------------------===//
// Symbol Manipulation
//===----------------------------------------------------------------------===//
@@ -443,17 +433,19 @@ MCSymbol *MCContext::getDirectionalLocalSymbol(unsigned LocalLabelVal,
return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
}
+// Create a section symbol, with a distinct one for each section of the same.
+// The first symbol is used for assembly code references.
template <typename Symbol>
Symbol *MCContext::getOrCreateSectionSymbol(StringRef Section) {
Symbol *R;
auto &SymEntry = getSymbolTableEntry(Section);
MCSymbol *Sym = SymEntry.second.Symbol;
- // A section symbol can not redefine regular symbols. There may be multiple
- // sections with the same name, in which case the first such section wins.
if (Sym && Sym->isDefined() &&
(!Sym->isInSection() || Sym->getSection().getBeginSymbol() != Sym))
reportError(SMLoc(), "invalid symbol redefinition");
- if (Sym && Sym->isUndefined()) {
+ // Use the symbol's index to track if it has been used as a section symbol.
+ // Set to -1 to catch potential bugs if misused as a symbol index.
+ if (Sym && Sym->getIndex() != -1u) {
R = cast<Symbol>(Sym);
} else {
SymEntry.second.Used = true;
@@ -461,6 +453,8 @@ Symbol *MCContext::getOrCreateSectionSymbol(StringRef Section) {
if (!Sym)
SymEntry.second.Symbol = R;
}
+ // Mark as section symbol.
+ R->setIndex(-1u);
return R;
}
@@ -568,7 +562,6 @@ MCSectionMachO *MCContext::getMachOSection(StringRef Segment, StringRef Section,
MCSectionMachO(Segment, Name.substr(Name.size() - Section.size()),
TypeAndAttributes, Reserved2, Kind, Begin);
R.first->second = Ret;
- allocInitialFragment(*Ret);
return Ret;
}
@@ -579,15 +572,8 @@ MCSectionELF *MCContext::createELFSectionImpl(StringRef Section, unsigned Type,
bool Comdat, unsigned UniqueID,
const MCSymbolELF *LinkedToSym) {
auto *R = getOrCreateSectionSymbol<MCSymbolELF>(Section);
- R->setBinding(ELF::STB_LOCAL);
- R->setType(ELF::STT_SECTION);
-
- auto *Ret = new (ELFAllocator.Allocate()) MCSectionELF(
+ return new (ELFAllocator.Allocate()) MCSectionELF(
Section, Type, Flags, EntrySize, Group, Comdat, UniqueID, R, LinkedToSym);
-
- auto *F = allocInitialFragment(*Ret);
- R->setFragment(F);
- return Ret;
}
MCSectionELF *
@@ -743,7 +729,6 @@ MCSectionGOFF *MCContext::getGOFFSection(SectionKind Kind, StringRef Name,
MCSectionGOFF(CachedName, Kind, IsVirtual, Attributes,
static_cast<MCSectionGOFF *>(Parent));
Iter->second = GOFFSection;
- allocInitialFragment(*GOFFSection);
return GOFFSection;
}
@@ -798,8 +783,7 @@ MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
MCSectionCOFF *Result = new (COFFAllocator.Allocate()) MCSectionCOFF(
CachedName, Characteristics, COMDATSymbol, Selection, UniqueID, Begin);
Iter->second = Result;
- auto *F = allocInitialFragment(*Result);
- Begin->setFragment(F);
+ Begin->setFragment(&Result->getDummyFragment());
return Result;
}
@@ -870,8 +854,6 @@ MCSectionWasm *MCContext::getWasmSection(const Twine &Section, SectionKind Kind,
MCSectionWasm(CachedName, Kind, Flags, GroupSym, UniqueID, Begin);
Entry.second = Result;
- auto *F = allocInitialFragment(*Result);
- Begin->setFragment(F);
return Result;
}
@@ -927,24 +909,11 @@ MCSectionXCOFF *MCContext::getXCOFFSection(
MultiSymbolsAllowed);
Entry.second = Result;
-
- auto *F = allocInitialFragment(*Result);
-
- // We might miss calculating the symbols difference as absolute value before
- // adding fixups when symbol_A without the fragment set is the csect itself
- // and symbol_B is in it.
- // TODO: Currently we only set the fragment for XMC_PR csects and DWARF
- // sections because we don't have other cases that hit this problem yet.
- if (IsDwarfSec || CsectProp->MappingClass == XCOFF::XMC_PR)
- QualName->setFragment(F);
-
return Result;
}
MCSectionSPIRV *MCContext::getSPIRVSection() {
MCSectionSPIRV *Result = new (SPIRVAllocator.Allocate()) MCSectionSPIRV();
-
- allocInitialFragment(*Result);
return Result;
}
@@ -964,7 +933,6 @@ MCSectionDXContainer *MCContext::getDXContainerSection(StringRef Section,
new (DXCAllocator.Allocate()) MCSectionDXContainer(Name, K, nullptr);
// The first fragment will store the header
- allocInitialFragment(*MapIt->second);
return MapIt->second;
}
diff --git a/llvm/lib/MC/MCELFStreamer.cpp b/llvm/lib/MC/MCELFStreamer.cpp
index b8cbaea5..38744a0 100644
--- a/llvm/lib/MC/MCELFStreamer.cpp
+++ b/llvm/lib/MC/MCELFStreamer.cpp
@@ -89,7 +89,9 @@ void MCELFStreamer::changeSection(MCSection *Section, uint32_t Subsection) {
getWriter().markGnuAbi();
MCObjectStreamer::changeSection(Section, Subsection);
- Asm.registerSymbol(*Section->getBeginSymbol());
+ auto *Sym = static_cast<MCSymbolELF *>(Section->getBeginSymbol());
+ Sym->setBinding(ELF::STB_LOCAL);
+ Sym->setType(ELF::STT_SECTION);
}
void MCELFStreamer::emitWeakReference(MCSymbol *Alias, const MCSymbol *Target) {
diff --git a/llvm/lib/MC/MCMachOStreamer.cpp b/llvm/lib/MC/MCMachOStreamer.cpp
index 8c3332c..4934815 100644
--- a/llvm/lib/MC/MCMachOStreamer.cpp
+++ b/llvm/lib/MC/MCMachOStreamer.cpp
@@ -140,6 +140,8 @@ void MCMachOStreamer::changeSection(MCSection *Section, uint32_t Subsection) {
MCSymbol *Label = getContext().createLinkerPrivateTempSymbol();
Section->setBeginSymbol(Label);
HasSectionLabel[Section] = true;
+ if (!Label->isInSection())
+ emitLabel(Label);
}
}
diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
index fcd5cbf..f046552 100644
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -185,10 +185,10 @@ void MCObjectStreamer::emitLabel(MCSymbol *Symbol, SMLoc Loc) {
getAssembler().registerSymbol(*Symbol);
- // If there is a current fragment, mark the symbol as pointing into it.
- // Otherwise queue the label and set its fragment pointer when we emit the
- // next fragment.
- MCFragment *F = getCurrentFragment();
+ // Set the fragment and offset. This function might be called by
+ // changeSection, when the section stack top hasn't been changed to the new
+ // section.
+ MCFragment *F = CurFrag;
Symbol->setFragment(F);
Symbol->setOffset(F->getContents().size());
@@ -247,6 +247,15 @@ void MCObjectStreamer::changeSection(MCSection *Section, uint32_t Subsection) {
assert(Section && "Cannot switch to a null section!");
getContext().clearDwarfLocSeen();
+ // Register the section and create an initial fragment for subsection 0
+ // if `Subsection` is non-zero.
+ bool NewSec = getAssembler().registerSection(*Section);
+ MCFragment *F0 = nullptr;
+ if (NewSec && Subsection) {
+ changeSection(Section, 0);
+ F0 = CurFrag;
+ }
+
auto &Subsections = Section->Subsections;
size_t I = 0, E = Subsections.size();
while (I != E && Subsections[I].first < Subsection)
@@ -262,12 +271,13 @@ void MCObjectStreamer::changeSection(MCSection *Section, uint32_t Subsection) {
Section->CurFragList = &Subsections[I].second;
CurFrag = Section->CurFragList->Tail;
- getAssembler().registerSection(*Section);
-}
-
-void MCObjectStreamer::switchSectionNoPrint(MCSection *Section) {
- MCStreamer::switchSectionNoPrint(Section);
- changeSection(Section, 0);
+ // Define the section symbol at subsection 0's initial fragment if required.
+ if (!NewSec)
+ return;
+ if (auto *Sym = Section->getBeginSymbol()) {
+ Sym->setFragment(Subsection ? F0 : CurFrag);
+ getAssembler().registerSymbol(*Sym);
+ }
}
void MCObjectStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
diff --git a/llvm/lib/MC/MCSection.cpp b/llvm/lib/MC/MCSection.cpp
index 023f7f2..e738a22 100644
--- a/llvm/lib/MC/MCSection.cpp
+++ b/llvm/lib/MC/MCSection.cpp
@@ -22,8 +22,7 @@ MCSection::MCSection(SectionVariant V, StringRef Name, bool IsText, bool IsBss,
MCSymbol *Begin)
: Begin(Begin), HasInstructions(false), IsRegistered(false), IsText(IsText),
IsBss(IsBss), LinkerRelaxable(false), Name(Name), Variant(V) {
- // The initial subsection number is 0. Create a fragment list.
- CurFragList = &Subsections.emplace_back(0u, FragList{}).second;
+ DummyFragment.setParent(this);
}
MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) {
diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index db3e9b3..add021b 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -1314,9 +1314,20 @@ void MCStreamer::emitZerofill(MCSection *, MCSymbol *, uint64_t, Align, SMLoc) {
}
void MCStreamer::emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
uint64_t Size, Align ByteAlignment) {}
-void MCStreamer::changeSection(MCSection *Section, uint32_t) {
- CurFrag = &Section->getDummyFragment();
+
+void MCStreamer::changeSection(MCSection *Sec, uint32_t) {
+ CurFrag = &Sec->getDummyFragment();
+ auto *Sym = Sec->getBeginSymbol();
+ if (!Sym || !Sym->isUndefined())
+ return;
+ // In Mach-O, DWARF sections use Begin as a temporary label, requiring a label
+ // definition, unlike section symbols in other file formats.
+ if (getContext().getObjectFileType() == MCContext::IsMachO)
+ emitLabel(Sym);
+ else
+ Sym->setFragment(CurFrag);
}
+
void MCStreamer::emitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {}
void MCStreamer::emitBytes(StringRef Data) {}
void MCStreamer::emitBinaryData(StringRef Data) { emitBytes(Data); }
@@ -1358,9 +1369,6 @@ void MCStreamer::switchSection(MCSection *Section, uint32_t Subsection) {
changeSection(Section, Subsection);
SectionStack.back().first = MCSectionSubPair(Section, Subsection);
assert(!Section->hasEnded() && "Section already ended");
- MCSymbol *Sym = Section->getBeginSymbol();
- if (Sym && !Sym->isInSection())
- emitLabel(Sym);
}
}
@@ -1387,9 +1395,6 @@ void MCStreamer::switchSectionNoPrint(MCSection *Section) {
SectionStack.back().second = SectionStack.back().first;
SectionStack.back().first = MCSectionSubPair(Section, 0);
changeSection(Section, 0);
- MCSymbol *Sym = Section->getBeginSymbol();
- if (Sym && !Sym->isInSection())
- emitLabel(Sym);
}
MCSymbol *MCStreamer::endSection(MCSection *Section) {
diff --git a/llvm/lib/MC/MCXCOFFStreamer.cpp b/llvm/lib/MC/MCXCOFFStreamer.cpp
index 63381b4..78e4b95 100644
--- a/llvm/lib/MC/MCXCOFFStreamer.cpp
+++ b/llvm/lib/MC/MCXCOFFStreamer.cpp
@@ -36,6 +36,20 @@ XCOFFObjectWriter &MCXCOFFStreamer::getWriter() {
return static_cast<XCOFFObjectWriter &>(getAssembler().getWriter());
}
+void MCXCOFFStreamer::changeSection(MCSection *Section, uint32_t Subsection) {
+ MCObjectStreamer::changeSection(Section, Subsection);
+ auto *Sec = cast<MCSectionXCOFF>(Section);
+ // We might miss calculating the symbols difference as absolute value before
+ // adding fixups when symbol_A without the fragment set is the csect itself
+ // and symbol_B is in it.
+ // TODO: Currently we only set the fragment for XMC_PR csects and DWARF
+ // sections because we don't have other cases that hit this problem yet.
+ // if (IsDwarfSec || CsectProp->MappingClass == XCOFF::XMC_PR)
+ // QualName->setFragment(F);
+ if (Sec->isDwarfSect() || Sec->getMappingClass() == XCOFF::XMC_PR)
+ Sec->getQualNameSymbol()->setFragment(CurFrag);
+}
+
bool MCXCOFFStreamer::emitSymbolAttribute(MCSymbol *Sym,
MCSymbolAttr Attribute) {
auto *Symbol = cast<MCSymbolXCOFF>(Sym);
generated by cgit v1.1 at 2025-08-02 01:15:16 +0000