[ubsan] Don't add a --dynamic-list for ubsan symbols when building a shared

library. That results in the linker resolving all references to weak symbols in
the DSO to the definition from within that DSO. Ironically, this rarely causes
observable problems, except that it causes ubsan's own dynamic type check to
spuriously fail (because we fail to properly merge type_info object names).

llvm-svn: 210220

1 files changed, 8 insertions, 2 deletions

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index ee3b7ff3424..7817f826150 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -2033,17 +2033,23 @@ static void addLsanRT(const ToolChain &TC, const ArgList &Args,
 static void addUbsanRT(const ToolChain &TC, const ArgList &Args,
                        ArgStringList &CmdArgs, bool IsCXX,
                        bool HasOtherSanitizerRt) {
+  // Export symbols if we're not building a shared library. This allows two
+  // models: either every DSO containing ubsan-sanitized code contains the
+  // ubsan runtime, or the main executable does (or both).
+  const bool ExportSymbols = !Args.hasArg(options::OPT_shared);
+
   // Need a copy of sanitizer_common. This could come from another sanitizer
   // runtime; if we're not including one, include our own copy.
   if (!HasOtherSanitizerRt)
     addSanitizerRTLinkFlags(TC, Args, CmdArgs, "san", true, false);
 
-  addSanitizerRTLinkFlags(TC, Args, CmdArgs, "ubsan", false);
+  addSanitizerRTLinkFlags(TC, Args, CmdArgs, "ubsan", false, ExportSymbols);
 
   // Only include the bits of the runtime which need a C++ ABI library if
   // we're linking in C++ mode.
   if (IsCXX)
-    addSanitizerRTLinkFlags(TC, Args, CmdArgs, "ubsan_cxx", false);
+    addSanitizerRTLinkFlags(TC, Args, CmdArgs, "ubsan_cxx", false,
+                            ExportSymbols);
 }
 
 static void addDfsanRT(const ToolChain &TC, const ArgList &Args,