Command line option to enable support for segmented stacks:
-segmented-stacks.
Patch by Sanjoy Das!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138811 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/TargetMachine.cpp b/lib/Target/TargetMachine.cpp
index f74c8c3..fe8a7ce 100644
--- a/lib/Target/TargetMachine.cpp
+++ b/lib/Target/TargetMachine.cpp
@@ -47,6 +47,7 @@
   bool StrongPHIElim;
   bool HasDivModLibcall;
   bool AsmVerbosityDefault(false);
+  bool EnableSegmentedStacks;
 }
 
 static cl::opt<bool, true>
@@ -178,6 +179,12 @@
 FunctionSections("ffunction-sections",
   cl::desc("Emit functions into separate sections"),
   cl::init(false));
+static cl::opt<bool, true>
+SegmentedStacks("segmented-stacks",
+  cl::desc("Use segmented stacks if possible."),
+  cl::location(EnableSegmentedStacks),
+  cl::init(false));
+                         
 //---------------------------------------------------------------------------
 // TargetMachine Class
 //