[ELF] Add -Bno-symbolic

This option will be available in GNU ld 2.27 (https://sourceware.org/bugzilla/show_bug.cgi?id=27834).
This option can cancel previously specified -Bsymbolic and
-Bsymbolic-functions.  This is useful for excluding some links when the
default uses -Bsymbolic-functions.

Reviewed By: jhenderson, peter.smith

Differential Revision: https://reviews.llvm.org/D102383

lld/ELF/Config.h

@@ -143,8 +143,8 @@ struct Configuration {
   bool armHasMovtMovw = false;
   bool armJ1J2BranchEncoding = false;
   bool asNeeded = false;
-  bool bsymbolic;
-  bool bsymbolicFunctions;
+  bool bsymbolic = false;
+  bool bsymbolicFunctions = false;
   bool callGraphProfileSort;
   bool checkSections;
   bool compressDebugSections;

lld/ELF/Driver.cpp

@@ -953,8 +953,13 @@ static void readConfigs(opt::InputArgList &args) {
                    OPT_no_allow_multiple_definition, false) ||
       hasZOption(args, "muldefs");
   config->auxiliaryList = args::getStrings(args, OPT_auxiliary);
-  config->bsymbolic = args.hasArg(OPT_Bsymbolic);
-  config->bsymbolicFunctions = args.hasArg(OPT_Bsymbolic_functions);
+  if (opt::Arg *arg = args.getLastArg(OPT_Bno_symbolic, OPT_Bsymbolic_functions,
+                                      OPT_Bsymbolic)) {
+    if (arg->getOption().matches(OPT_Bsymbolic_functions))
+      config->bsymbolicFunctions = true;
+    else if (arg->getOption().matches(OPT_Bsymbolic))
+      config->bsymbolic = true;
+  }
   config->checkSections =
       args.hasFlag(OPT_check_sections, OPT_no_check_sections, true);
   config->chroot = args.getLastArgValue(OPT_chroot);
@@ -1316,8 +1321,7 @@ static void readConfigs(opt::InputArgList &args) {
   // When producing an executable, --dynamic-list specifies non-local defined
   // symbols which are required to be exported. When producing a shared object,
   // symbols not specified by --dynamic-list are non-preemptible.
-  config->symbolic =
-      args.hasArg(OPT_Bsymbolic) || args.hasArg(OPT_dynamic_list);
+  config->symbolic = config->bsymbolic || args.hasArg(OPT_dynamic_list);
   for (auto *arg : args.filtered(OPT_dynamic_list))
     if (Optional<MemoryBufferRef> buffer = readFile(arg->getValue()))
       readDynamicList(*buffer);

lld/ELF/Options.td

@@ -36,10 +36,12 @@ multiclass B<string name, string help1, string help2> {
 
 defm auxiliary: Eq<"auxiliary", "Set DT_AUXILIARY field to the specified name">;
 
-def Bsymbolic: F<"Bsymbolic">, HelpText<"Bind defined symbols locally">;
+def Bno_symbolic: F<"Bno-symbolic">, HelpText<"Don't bind default visibility defined symbols locally for -shared (default)">;
+
+def Bsymbolic: F<"Bsymbolic">, HelpText<"Bind default visibility defined symbols locally for -shared">;
 
 def Bsymbolic_functions: F<"Bsymbolic-functions">,
-  HelpText<"Bind defined function symbols locally">;
+  HelpText<"Bind default visibility defined function symbols locally for -shared">;
 
 def Bdynamic: F<"Bdynamic">, HelpText<"Link against shared libraries (default)">;
 

lld/docs/ReleaseNotes.rst

@@ -24,7 +24,10 @@ Non-comprehensive list of changes in this release
 ELF Improvements
 ----------------
 
-* ...
+* ``-Bsymbolic -Bsymbolic-functions`` has been changed to behave the same as ``-Bsymbolic-functions``. This matches GNU ld.
+  (`D102461 <https://reviews.llvm.org/D102461>`_)
+* ``-Bno-symbolic`` has been added.
+  (`D102461 <https://reviews.llvm.org/D102461>`_)
 
 Breaking changes
 ----------------

lld/docs/ld.lld.1

@@ -72,10 +72,19 @@ field to the specified name.
 Link against shared libraries.
 .It Fl -Bstatic , Fl -static , Fl -dn
 Do not link against shared libraries.
-.It Fl -Bsymbolic
-Bind defined symbols locally.
-.It Fl -Bsymbolic-functions
-Bind defined function symbols locally.
+.It Fl Bno-symbolic
+Don't bind default visibility defined symbols locally for
+.Fl shared
+(default).
+.It Fl Bsymbolic
+Bind default visibility defined symbols locally for
+.Fl shared.
+Also set the
+.Dv DF_SYMBOLIC
+flag.
+.It Fl Bsymbolic-functions
+Bind default visibility defined function symbols locally for
+.Fl shared.
 .It Fl -build-id Ns = Ns Ar value
 Generate a build ID note.
 .Ar value

lld/test/ELF/bsymbolic.s

@@ -19,8 +19,16 @@
 # RUN: ld.lld -shared -Bsymbolic-functions -Bsymbolic %t/a.o %t/b.o -o %t.so
 # RUN: cmp %t.so %t2.so
 # RUN: ld.lld -shared -Bsymbolic -Bsymbolic-functions %t/a.o %t/b.o -o %t.so
+# RUN: cmp %t.so %t1.so
+# RUN: ld.lld -shared -Bno-symbolic -Bsymbolic %t/a.o %t/b.o -o %t.so
 # RUN: cmp %t.so %t2.so
 
+## -Bno-symbolic can cancel previously specified -Bsymbolic and -Bsymbolic-functions.
+# RUN: ld.lld -shared -Bsymbolic -Bno-symbolic %t/a.o %t/b.o -o %t.so
+# RUN: cmp %t.so %t0.so
+# RUN: ld.lld -shared -Bsymbolic-functions -Bno-symbolic %t/a.o %t/b.o -o %t.so
+# RUN: cmp %t.so %t0.so
+
 # REL_DEF:      .rela.dyn {
 # REL_DEF-NEXT:   R_X86_64_RELATIVE -
 # REL_DEF-NEXT:   R_X86_64_RELATIVE -