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[lld][ELF] Use the containing symbol, not the referenced symbol, for undefined symbol errors. #70800

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[lld][ELF] Use the containing symbol, not the referenced symbol, for undefined symbol errors. #70800

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30 changes: 29 additions & 1 deletion lld/ELF/Relocations.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -693,6 +693,34 @@ static const Symbol *getAlternativeSpelling(const Undefined &sym,
return nullptr;
}

static Symbol &
getSymAtOffset(InputSectionBase &sec, uint64_t off, Symbol &sym) {
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Would getSymContainingOffset() be a better name, as we're looking for the symbol with off in the range [sym->off,, sym->off + sym->size) .

ArrayRef<Symbol *> syms;
switch (config->ekind) {
case ELF32LEKind:
syms = sec.getFile<ELF32LE>()->getSymbols();
break;
case ELF32BEKind:
syms = sec.getFile<ELF32BE>()->getSymbols();
break;
case ELF64LEKind:
syms = sec.getFile<ELF64LE>()->getSymbols();
break;
case ELF64BEKind:
syms = sec.getFile<ELF64BE>()->getSymbols();
break;
default:
llvm_unreachable("");
}
// Get the symbol that contains this offset.
for (Symbol *b : syms)
if (auto *d = dyn_cast_or_null<Defined>(b))
if (d->section == &sec && d->value <= off && off < d->value + d->size)
return *d;
// Fall back to the supplied symbol otherwise.
return sym;
}

static void reportUndefinedSymbol(const UndefinedDiag &undef,
bool correctSpelling) {
Undefined &sym = *undef.sym;
Expand Down Expand Up @@ -739,7 +767,7 @@ static void reportUndefinedSymbol(const UndefinedDiag &undef,
uint64_t offset = l.offset;

msg += "\n>>> referenced by ";
std::string src = sec.getSrcMsg(sym, offset);
std::string src = sec.getSrcMsg(getSymAtOffset(sec, offset, sym), offset);
if (!src.empty())
msg += src + "\n>>> ";
msg += sec.getObjMsg(offset);
Expand Down