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Change how to handle --unresolved-symbols=ignore

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Previously, we turned unresolved undefined symbols into dynamic
symbols. This patch changed the behavior so that such symbols
are turned into non-dynamic absolute symbols with value zero.

This change is needed by Gentoo's dev-libs/wayland-protocols-1.21
package.
This commit is contained in:
Rui Ueyama 2021-06-20 14:31:33 +09:00
parent 04f82b4b13
commit 9519e4ce20
4 changed files with 40 additions and 5 deletions
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11
main.cc
View File

@ -450,11 +450,18 @@ int do_main(int argc, char **argv) {
// Convert weak symbols to absolute symbols with value 0.
convert_undefined_weak_symbols(ctx);
// If we do not handle undefined symbols as errors, such symbols
// are converted to absolute symbols with value 0.
if (ctx.arg.unresolved_symbols != UnresolvedKind::ERROR) {
tbb::parallel_for_each(ctx.objs, [&](ObjectFile<E> *file) {
file->ignore_unresolved_symbols(ctx);
});
}
// If we are linking a .so file, remaining undefined symbols does
// not cause a linker error. Instead, they are treated as if they
// were imported symbols.
if ((ctx.arg.shared && !ctx.arg.z_defs) ||
ctx.arg.unresolved_symbols != UnresolvedKind::ERROR) {
if (ctx.arg.shared && !ctx.arg.z_defs) {
Timer t(ctx, "claim_unresolved_symbols");
tbb::parallel_for_each(ctx.objs, [&](ObjectFile<E> *file) {
file->claim_unresolved_symbols(ctx);

1
mold.h
View File

@ -935,6 +935,7 @@ public:
void convert_undefined_weak_symbols(Context<E> &ctx);
void resolve_comdat_groups();
void eliminate_duplicate_comdat_groups();
void ignore_unresolved_symbols(Context<E> &ctx);
void claim_unresolved_symbols(Context<E> &ctx);
void scan_relocations(Context<E> &ctx);
void convert_common_symbols(Context<E> &ctx);

31
object_file.cc
View File

@ -934,6 +934,34 @@ void ObjectFile<E>::eliminate_duplicate_comdat_groups() {
}
}
template <typename E>
void ObjectFile<E>::ignore_unresolved_symbols(Context<E> &ctx) {
if (!this->is_alive)
return;
for (i64 i = first_global; i < this->symbols.size(); i++) {
const ElfSym<E> &esym = elf_syms[i];
Symbol<E> &sym = *this->symbols[i];
if (esym.is_defined())
continue;
std::lock_guard lock(sym.mu);
if (sym.sym_idx == -1 || sym.is_undef()) {
if (sym.file && sym.file->priority < this->priority)
continue;
if (ctx.arg.unresolved_symbols == UnresolvedKind::WARN)
Warn(ctx) << "undefined symbol: " << *this << ": " << sym;
sym.file = this;
sym.input_section = nullptr;
sym.value = 0;
sym.sym_idx = i;
sym.is_imported = false;
sym.is_exported = false;
}
}
}
template <typename E>
void ObjectFile<E>::claim_unresolved_symbols(Context<E> &ctx) {
if (!this->is_alive)
@ -942,7 +970,6 @@ void ObjectFile<E>::claim_unresolved_symbols(Context<E> &ctx) {
for (i64 i = first_global; i < this->symbols.size(); i++) {
const ElfSym<E> &esym = elf_syms[i];
Symbol<E> &sym = *this->symbols[i];
if (esym.is_defined())
continue;
@ -951,8 +978,6 @@ void ObjectFile<E>::claim_unresolved_symbols(Context<E> &ctx) {
if (sym.file && sym.file->priority < this->priority)
continue;
if (ctx.arg.unresolved_symbols == UnresolvedKind::WARN)
Warn(ctx) << "undefined symbol: " << *this << ": " << sym;
sym.file = this;
sym.value = 0;
sym.sym_idx = i;

2
test/unresolved-symbols.sh
View File

@ -17,6 +17,8 @@ cmd="clang -fuse-ld=`pwd`/../mold -o $t/exe $t/a.o"
$cmd -Wl,-unresolved-symbols=ignore-all
! readelf --dyn-syms $t/exe | grep -w foo || false
$cmd -Wl,-unresolved-symbols=report-all -Wl,--warn-unresolved-symbols 2>&1 | \
grep -q 'undefined.*foo'