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
diff --git a/lib/IR/Attributes.cpp b/lib/IR/Attributes.cpp
index 4bd2391..964a404 100644
--- a/lib/IR/Attributes.cpp
+++ b/lib/IR/Attributes.cpp
@@ -206,6 +206,8 @@
     Result += "ssp ";
   if (hasAttribute(Attribute::StackProtectReq))
     Result += "sspreq ";
+  if (hasAttribute(Attribute::StackProtectStrong))
+    Result += "sspstrong ";
   if (hasAttribute(Attribute::NoRedZone))
     Result += "noredzone ";
   if (hasAttribute(Attribute::NoImplicitFloat))
@@ -487,6 +489,7 @@
   case Attribute::AddressSafety:   return 1ULL << 32;
   case Attribute::MinSize:         return 1ULL << 33;
   case Attribute::NoDuplicate:     return 1ULL << 34;
+  case Attribute::StackProtectStrong: return 1ULL << 35;
   }
   llvm_unreachable("Unsupported attribute type");
 }