visit(file);
}
-// Force Sym to be entered in the output. Used for -u or equivalent.
+// Force Sym to be entered in the output.
static void handleUndefined(Symbol *sym) {
// Since a symbol may not be used inside the program, LTO may
// eliminate it. Mark the symbol as "used" to prevent it.
sym->isUsedInRegularObj = true;
- // GNU linkers allow -u foo -ldef -lref. We should not treat it as a backward
- // reference.
- backwardReferences.erase(sym);
-
if (sym->isLazy())
sym->fetch();
}
Undefined{nullptr, name, STB_GLOBAL, STV_DEFAULT, 0});
}
+static Symbol *addUnusedUndefined(StringRef name) {
+ Undefined sym{nullptr, name, STB_GLOBAL, STV_DEFAULT, 0};
+ sym.isUsedInRegularObj = false;
+ return symtab->addSymbol(sym);
+}
+
// This function is where all the optimizations of link-time
// optimization takes place. When LTO is in use, some input files are
// not in native object file format but in the LLVM bitcode format.
for (auto *arg : args.filtered(OPT_trace_symbol))
symtab->insert(arg->getValue())->traced = true;
+ // Handle -u/--undefined before input files. If both a.a and b.so define foo,
+ // -u foo a.a b.so will fetch a.a.
+ for (StringRef name : config->undefined)
+ addUnusedUndefined(name);
+
// Add all files to the symbol table. This will add almost all
// symbols that we need to the symbol table. This process might
// add files to the link, via autolinking, these files are always
for (StringRef name : script->referencedSymbols)
addUndefined(name);
- // Handle the `--undefined <sym>` options.
- for (StringRef arg : config->undefined)
- if (Symbol *sym = symtab->find(arg))
- handleUndefined(sym);
+ // Prevent LTO from removing any definition referenced by -u.
+ for (StringRef name : config->undefined)
+ if (Defined *sym = dyn_cast_or_null<Defined>(symtab->find(name)))
+ sym->isUsedInRegularObj = true;
// If an entry symbol is in a static archive, pull out that file now.
if (Symbol *sym = symtab->find(config->entry))
# UNK-UNDEFINED-SO: ]
# Added undefined symbols should appear in the dynamic table if necessary.
-# RUN: ld.lld -shared -o %t5 %t.o -u export
-# RUN: llvm-readobj --dyn-symbols %t5 | \
+# RUN: ld.lld -shared -soname=t -o %t.so %t.o -u export
+# RUN: llvm-readobj --dyn-symbols %t.so | \
# RUN: FileCheck --check-prefix=EXPORT-SO %s
# EXPORT-SO: DynamicSymbols [
# EXPORT-SO: Name: export
# EXPORT-SO: ]
+## Test that we handle -u before input files: if we handle -u after
+## %t.so, foo would be undefined in the output.
+# RUN: rm -f %t.a && llvm-ar rc %t.a %t.o
+# RUN: ld.lld -u export %t.a %t.so -o %t5
+# RUN: llvm-readobj --dyn-symbols %t5 | FileCheck --check-prefix=EXPORT-SO %s
+
.globl _start
_start: