[asan] A clang flag to enable ELF globals-gc.

This feature is subtly broken when the linker is gold 2.26 or
earlier. See the following bug for details:
  https://sourceware.org/bugzilla/show_bug.cgi?id=19002

Since the decision needs to be made at compilation time, we can not
test the linker version. The flag is off by default on ELF targets,
and on otherwise.

llvm-svn: 302591

1 files changed, 10 insertions, 0 deletions

diff --git a/clang/lib/Driver/SanitizerArgs.cpp b/clang/lib/Driver/SanitizerArgs.cpp
index b6fc9e9ba4f..9ab2e176845 100644
--- a/clang/lib/Driver/SanitizerArgs.cpp
+++ b/clang/lib/Driver/SanitizerArgs.cpp
@@ -566,6 +566,13 @@ SanitizerArgs::SanitizerArgs(const ToolChain &TC,
     AsanUseAfterScope = Args.hasFlag(
         options::OPT_fsanitize_address_use_after_scope,
         options::OPT_fno_sanitize_address_use_after_scope, AsanUseAfterScope);
+
+    // As a workaround for a bug in gold 2.26 and earlier, dead stripping of
+    // globals in ASan is disabled by default on ELF targets.
+    // See https://sourceware.org/bugzilla/show_bug.cgi?id=19002
+    AsanGlobalsDeadStripping =
+        !TC.getTriple().isOSBinFormatELF() ||
+        Args.hasArg(options::OPT_fsanitize_address_globals_dead_stripping);
   } else {
     AsanUseAfterScope = false;
   }
@@ -717,6 +724,9 @@ void SanitizerArgs::addArgs(const ToolChain &TC, const llvm::opt::ArgList &Args,
   if (AsanUseAfterScope)
     CmdArgs.push_back("-fsanitize-address-use-after-scope");
 
+  if (AsanGlobalsDeadStripping)
+    CmdArgs.push_back("-fsanitize-address-globals-dead-stripping");
+
   // MSan: Workaround for PR16386.
   // ASan: This is mainly to help LSan with cases such as
   // https://code.google.com/p/address-sanitizer/issues/detail?id=373