Add the IR attribute 'sspstrong'.

SSPStrong applies a heuristic to insert stack protectors in these situations:

* A Protector is required for functions which contain an array, regardless of
  type or length.

* A Protector is required for functions which contain a structure/union which
  contains an array, regardless of type or length.  Note, there is no limit to
  the depth of nesting.

* A protector is required when the address of a local variable (i.e., stack
  based variable) is exposed. (E.g., such as through a local whose address is
  taken as part of the RHS of an assignment or a local whose address is taken as
  part of a function argument.)

This patch implements the SSPString attribute to be equivalent to
SSPRequired. This will change in a subsequent patch.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173230 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/StackProtector.cpp

@@ -141,6 +141,12 @@ bool StackProtector::RequiresStackProtector() const {
                                       Attribute::StackProtectReq))
     return true;
 
+  // FIXME: Dummy SSP-strong implementation.  Default to required until
+  // strong heuristic is implemented.
+  if (F->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
+                                        Attribute::StackProtectStrong))
+    return true;
+
   if (!F->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
                                        Attribute::StackProtect))
     return false;