Add 'nonnull', a new parameter and return attribute which indicates that the pointer is not null. Instcombine will elide comparisons between these and null. Patch by Luqman Aden!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209185 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/Argument.h

@@ -55,6 +55,10 @@ public:
   /// For example in "void foo(int a, float b)" a is 0 and b is 1.
   unsigned getArgNo() const;
 
+  /// \brief Return true if this argument has the nonnull attribute on it in
+  /// its containing function.
+  bool hasNonNullAttr() const;
+
   /// \brief Return true if this argument has the byval attribute on it in its
   /// containing function.
   bool hasByValAttr() const;

include/llvm/IR/Attributes.h

@@ -86,6 +86,7 @@ public:
     NoInline,              ///< inline=never
     NonLazyBind,           ///< Function is called early and/or
                            ///< often, so lazy binding isn't worthwhile
+    NonNull,               ///< Pointer is known to be not null
     NoRedZone,             ///< Disable redzone
     NoReturn,              ///< Mark the function as not returning
     NoUnwind,              ///< Function doesn't unwind stack