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[LTO][ELF][lld] Use unique string saver in ELF bitcode symbol parsing #106670

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Sep 5, 2024
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8 changes: 6 additions & 2 deletions lld/ELF/InputFiles.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -1744,8 +1744,10 @@ createBitcodeSymbol(Symbol *&sym, const std::vector<bool> &keptComdats,
uint8_t type = objSym.isTLS() ? STT_TLS : STT_NOTYPE;
uint8_t visibility = mapVisibility(objSym.getVisibility());

// Symbols can be duplicated in bitcode files because of '#include' and
// linkonce_odr. Use unique_saver to save symbol names for de-duplication.
if (!sym)
sym = symtab.insert(saver().save(objSym.getName()));
sym = symtab.insert(unique_saver().save(objSym.getName()));

int c = objSym.getComdatIndex();
if (objSym.isUndefined() || (c != -1 && !keptComdats[c])) {
Expand Down Expand Up @@ -1797,7 +1799,9 @@ void BitcodeFile::parseLazy() {
symbols = std::make_unique<Symbol *[]>(numSymbols);
for (auto [i, irSym] : llvm::enumerate(obj->symbols()))
if (!irSym.isUndefined()) {
auto *sym = symtab.insert(saver().save(irSym.getName()));
// Symbols can be duplicated in bitcode files because of '#include' and
// linkonce_odr. Use unique_saver to save symbol names for de-duplication.
auto *sym = symtab.insert(unique_saver().save(irSym.getName()));
sym->resolve(LazySymbol{*this});
symbols[i] = sym;
}
Expand Down
8 changes: 7 additions & 1 deletion lld/include/lld/Common/CommonLinkerContext.h
Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@ class CommonLinkerContext {

llvm::BumpPtrAllocator bAlloc;
llvm::StringSaver saver{bAlloc};
llvm::UniqueStringSaver unique_saver{bAlloc};
llvm::DenseMap<void *, SpecificAllocBase *> instances;

ErrorHandler e;
Expand All @@ -54,8 +55,13 @@ template <typename T = CommonLinkerContext> T &context() {

bool hasContext();

inline llvm::StringSaver &saver() { return context().saver; }
inline llvm::BumpPtrAllocator &bAlloc() { return context().bAlloc; }
inline llvm::StringSaver &saver() { return context().saver; }
inline llvm::UniqueStringSaver &unique_saver() {
// FIXME: Look into other places where duplications are common in saved
// strings and unique saver make sense.
return context().unique_saver;
}
} // namespace lld

#endif
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