[Driver] SafeStack does not need a runtime library on Fuchsia

Patch by Roland McGrath

Differential Revision: https://reviews.llvm.org/D36779

llvm-svn: 311034
diff --git a/clang/lib/Driver/SanitizerArgs.cpp b/clang/lib/Driver/SanitizerArgs.cpp
index e411629..0a73775 100644
--- a/clang/lib/Driver/SanitizerArgs.cpp
+++ b/clang/lib/Driver/SanitizerArgs.cpp
@@ -605,6 +605,11 @@
     AsanUseAfterScope = false;
   }
 
+  if (AllAddedKinds & SafeStack) {
+    // SafeStack runtime is built into the system on Fuchsia.
+    SafeStackRuntime = !TC.getTriple().isOSFuchsia();
+  }
+
   // Parse -link-cxx-sanitizer flag.
   LinkCXXRuntimes =
       Args.hasArg(options::OPT_fsanitize_link_cxx_runtime) || D.CCCIsCXX();