[Driver][Darwin] Disable default stack protector levels in freestanding mode.

Currently -fstack-protector is on by default when using -ffreestanding.
Change the default behavior to have it off when using -ffreestanding.

rdar://problem/14089363

llvm-svn: 289005

1 files changed, 8 insertions, 1 deletions

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index ae38723..661e6f4 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -5279,9 +5279,12 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   Args.AddLastArg(CmdArgs, options::OPT_ftlsmodel_EQ);
 
   // -fhosted is default.
+  bool IsHosted = true;
   if (Args.hasFlag(options::OPT_ffreestanding, options::OPT_fhosted, false) ||
-      KernelOrKext)
+      KernelOrKext) {
     CmdArgs.push_back("-ffreestanding");
+    IsHosted = false;
+  }
 
   // Forward -f (flag) options which we can pass directly.
   Args.AddLastArg(CmdArgs, options::OPT_femit_all_decls);
@@ -5414,6 +5417,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   } else {
     StackProtectorLevel =
         getToolChain().GetDefaultStackProtectorLevel(KernelOrKext);
+    // Only use a default stack protector on Darwin in case -ffreestanding
+    // is not specified.
+    if (Triple.isOSDarwin() && !IsHosted)
+      StackProtectorLevel = 0;
   }
   if (StackProtectorLevel) {
     CmdArgs.push_back("-stack-protector");