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

include/llvm/Target/TargetOptions.h

@@ -158,6 +158,8 @@ namespace llvm {
   /// instead of an ISD::TRAP node.
   extern StringRef getTrapFunctionName();
 
+  extern bool EnableSegmentedStacks;
+
 } // End llvm namespace
 
 #endif

lib/Target/TargetMachine.cpp

@@ -47,6 +47,7 @@ namespace llvm {
   bool StrongPHIElim;
   bool HasDivModLibcall;
   bool AsmVerbosityDefault(false);
+  bool EnableSegmentedStacks;
 }
 
 static cl::opt<bool, true>
@@ -178,6 +179,12 @@ static cl::opt<bool>
 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
 //