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[ELF] Add a dummySym member to Ctx

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This ensures subsequent calls to elf::postScanRelocations with a new Ctx
will correctly use an instance with the right internalFile (with the old
one presumably deleted, even). It also avoids having to create a new
instance in elf::getErrorPlace, and will allow more uses of such a dummy
symbol in future commits.

Reviewers: MaskRay

Reviewed By: MaskRay

Pull Request: https://github.com/llvm/llvm-project/pull/150796
This commit is contained in:
Jessica Clarke 2025-07-30 17:03:34 +01:00 committed by GitHub
parent 75e5a70577
commit 58e6bc87b7
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GPG Key ID: B5690EEEBB952194
4 changed files with 5 additions and 4 deletions
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2
lld/ELF/Config.h
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@ -702,6 +702,8 @@ struct Ctx : CommonLinkerContext {
std::unique_ptr<llvm::TarWriter> tar;
// InputFile for linker created symbols with no source location.
InputFile *internalFile = nullptr;
// Dummy Undefined for relocations without a symbol.
Undefined *dummySym = nullptr;
// True if symbols can be exported (isExported) or preemptible.
bool hasDynsym = false;
// True if SHT_LLVM_SYMPART is used.

1
lld/ELF/Driver.cpp
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@ -3140,6 +3140,7 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &args) {
ctx.symtab->insert(arg->getValue())->traced = true;
ctx.internalFile = createInternalFile(ctx, "<internal>");
ctx.dummySym = make<Undefined>(ctx.internalFile, "", STB_LOCAL, 0, 0);
// Handle -u/--undefined before input files. If both a.a and b.so define foo,
// -u foo a.a b.so will extract a.a.

3
lld/ELF/Relocations.cpp
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@ -1948,13 +1948,12 @@ void elf::postScanRelocations(Ctx &ctx) {
GotSection *got = ctx.in.got.get();
if (ctx.needsTlsLd.load(std::memory_order_relaxed) && got->addTlsIndex()) {
static Undefined dummy(ctx.internalFile, "", STB_LOCAL, 0, 0);
if (ctx.arg.shared)
ctx.mainPart->relaDyn->addReloc(
{ctx.target->tlsModuleIndexRel, got, got->getTlsIndexOff()});
else
got->addConstant({R_ADDEND, ctx.target->symbolicRel,
got->getTlsIndexOff(), 1, &dummy});
got->getTlsIndexOff(), 1, ctx.dummySym});
}
assert(ctx.symAux.size() == 1);

3
lld/ELF/Target.cpp
View File

@ -105,10 +105,9 @@ ErrorPlace elf::getErrorPlace(Ctx &ctx, const uint8_t *loc) {
if (isecLoc <= loc && loc < isecLoc + isec->getSize()) {
std::string objLoc = isec->getLocation(loc - isecLoc);
// Return object file location and source file location.
Undefined dummy(ctx.internalFile, "", STB_LOCAL, 0, 0);
ELFSyncStream msg(ctx, DiagLevel::None);
if (isec->file)
msg << isec->getSrcMsg(dummy, loc - isecLoc);
msg << isec->getSrcMsg(*ctx.dummySym, loc - isecLoc);
return {isec, objLoc + ": ", std::string(msg.str())};
}
}