Add back commits r219835 and a fixed version of r219829.
The only difference from r219829 is using
getOrCreateSectionSymbol(*ELFSec)
instead of
GetOrCreateSymbol(ELFSec->getSectionName())
in ELFObjectWriter which causes us to use the correct section symbol even if
we have multiple sections with the same name.
Original messages:
r219829:
Correctly handle references to section symbols.
When processing assembly like
.long .text
we were creating a new undefined symbol .text. GAS on the other hand would
handle that as a reference to the .text section.
This patch implements that by creating the section symbols earlier so that
they are visible during asm parsing.
The patch also updates llvm-readobj to print the symbol number in the relocation
dump so that the test can differentiate between two sections with the same name.
r219835:
Allow forward references to section symbols.
llvm-svn: 220021
diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index 4577f01..e4442e1 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -81,23 +81,13 @@
struct ELFRelocationEntry {
uint64_t Offset; // Where is the relocation.
- bool UseSymbol; // Relocate with a symbol, not the section.
- union {
- const MCSymbol *Symbol; // The symbol to relocate with.
- const MCSectionData *Section; // The section to relocate with.
- };
+ const MCSymbol *Symbol; // The symbol to relocate with.
unsigned Type; // The type of the relocation.
uint64_t Addend; // The addend to use.
ELFRelocationEntry(uint64_t Offset, const MCSymbol *Symbol, unsigned Type,
uint64_t Addend)
- : Offset(Offset), UseSymbol(true), Symbol(Symbol), Type(Type),
- Addend(Addend) {}
-
- ELFRelocationEntry(uint64_t Offset, const MCSectionData *Section,
- unsigned Type, uint64_t Addend)
- : Offset(Offset), UseSymbol(false), Section(Section), Type(Type),
- Addend(Addend) {}
+ : Offset(Offset), Symbol(Symbol), Type(Type), Addend(Addend) {}
};
class ELFObjectWriter : public MCObjectWriter {
@@ -137,6 +127,14 @@
// Support lexicographic sorting.
bool operator<(const ELFSymbolData &RHS) const {
+ unsigned LHSType = MCELF::GetType(*SymbolData);
+ unsigned RHSType = MCELF::GetType(*RHS.SymbolData);
+ if (LHSType == ELF::STT_SECTION && RHSType != ELF::STT_SECTION)
+ return false;
+ if (LHSType != ELF::STT_SECTION && RHSType == ELF::STT_SECTION)
+ return true;
+ if (LHSType == ELF::STT_SECTION && RHSType == ELF::STT_SECTION)
+ return SectionIndex < RHS.SectionIndex;
return Name < RHS.Name;
}
};
@@ -651,22 +649,6 @@
WriteSymbol(Writer, MSD, Layout);
}
- // Write out a symbol table entry for each regular section.
- for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e;
- ++i) {
- const MCSectionELF &Section =
- static_cast<const MCSectionELF&>(i->getSection());
- if (Section.getType() == ELF::SHT_RELA ||
- Section.getType() == ELF::SHT_REL ||
- Section.getType() == ELF::SHT_STRTAB ||
- Section.getType() == ELF::SHT_SYMTAB ||
- Section.getType() == ELF::SHT_SYMTAB_SHNDX)
- continue;
- Writer.writeSymbol(0, ELF::STT_SECTION, 0, 0, ELF::STV_DEFAULT,
- SectionIndexMap.lookup(&Section), false);
- LastLocalSymbolIndex++;
- }
-
for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) {
ELFSymbolData &MSD = ExternalSymbolData[i];
MCSymbolData &Data = *MSD.SymbolData;
@@ -882,8 +864,11 @@
if (!RelocateWithSymbol) {
const MCSection *SecA =
(SymA && !SymA->isUndefined()) ? &SymA->getSection() : nullptr;
- const MCSectionData *SecAD = SecA ? &Asm.getSectionData(*SecA) : nullptr;
- ELFRelocationEntry Rec(FixupOffset, SecAD, Type, Addend);
+ auto *ELFSec = cast_or_null<MCSectionELF>(SecA);
+ MCSymbol *SectionSymbol =
+ ELFSec ? Asm.getContext().getOrCreateSectionSymbol(*ELFSec)
+ : nullptr;
+ ELFRelocationEntry Rec(FixupOffset, SectionSymbol, Type, Addend);
Relocations[FixupSection].push_back(Rec);
return;
}
@@ -1061,7 +1046,10 @@
Buf += Name.substr(Pos + Skip);
Name = Buf;
}
- MSD.Name = StrTabBuilder.add(Name);
+
+ // Sections have their own string table
+ if (MCELF::GetType(SD) != ELF::STT_SECTION)
+ MSD.Name = StrTabBuilder.add(Name);
if (MSD.SectionIndex == ELF::SHN_UNDEF)
UndefinedSymbolData.push_back(MSD);
@@ -1079,9 +1067,11 @@
for (auto i = Asm.file_names_begin(), e = Asm.file_names_end(); i != e; ++i)
FileSymbolData.push_back(StrTabBuilder.getOffset(*i));
- for (ELFSymbolData& MSD : LocalSymbolData)
- MSD.StringIndex = StrTabBuilder.getOffset(MSD.Name);
- for (ELFSymbolData& MSD : ExternalSymbolData)
+ for (ELFSymbolData &MSD : LocalSymbolData)
+ MSD.StringIndex = MCELF::GetType(*MSD.SymbolData) == ELF::STT_SECTION
+ ? 0
+ : StrTabBuilder.getOffset(MSD.Name);
+ for (ELFSymbolData &MSD : ExternalSymbolData)
MSD.StringIndex = StrTabBuilder.getOffset(MSD.Name);
for (ELFSymbolData& MSD : UndefinedSymbolData)
MSD.StringIndex = StrTabBuilder.getOffset(MSD.Name);
@@ -1097,8 +1087,6 @@
for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
LocalSymbolData[i].SymbolData->setIndex(Index++);
- Index += NumRegularSections;
-
for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
ExternalSymbolData[i].SymbolData->setIndex(Index++);
for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
@@ -1354,18 +1342,8 @@
for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
const ELFRelocationEntry &Entry = Relocs[e - i - 1];
-
- unsigned Index;
- if (Entry.UseSymbol) {
- Index = getSymbolIndexInSymbolTable(Asm, Entry.Symbol);
- } else {
- const MCSectionData *Sec = Entry.Section;
- if (Sec)
- Index = Sec->getOrdinal() + FileSymbolData.size() +
- LocalSymbolData.size() + 1;
- else
- Index = 0;
- }
+ unsigned Index =
+ Entry.Symbol ? getSymbolIndexInSymbolTable(Asm, Entry.Symbol) : 0;
if (is64Bit()) {
write(*F, Entry.Offset);