Consistent use of the noduplicate attribute.

The "noduplicate" attribute of call instructions is sometimes queried directly
and sometimes through the cannotDuplicate() predicate. This patch streamlines
all queries to use the cannotDuplicate() predicate. It also adds this predicate
to InvokeInst, to mirror what CallInst has.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204049 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/Instructions.h

@@ -3026,6 +3026,12 @@ public:
     addAttribute(AttributeSet::FunctionIndex, Attribute::NoUnwind);
   }
 
+  /// \brief Determine if the invoke cannot be duplicated.
+  bool cannotDuplicate() const {return hasFnAttr(Attribute::NoDuplicate); }
+  void setCannotDuplicate() {
+    addAttribute(AttributeSet::FunctionIndex, Attribute::NoDuplicate);
+  }
+
   /// \brief Determine if the call returns a structure through first
   /// pointer argument.
   bool hasStructRetAttr() const {