2 files changed, 77 insertions, 0 deletions

diff --git a/llvm/include/llvm/ADT/ArrayRef.h b/llvm/include/llvm/ADT/ArrayRef.h
index 0fff505d8d0..44400d591da 100644
--- a/llvm/include/llvm/ADT/ArrayRef.h
+++ b/llvm/include/llvm/ADT/ArrayRef.h
@@ -11,6 +11,7 @@
 #define LLVM_ADT_ARRAYREF_H
 
 #include "llvm/ADT/None.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include <vector>
 
@@ -43,6 +44,19 @@ namespace llvm {
     /// The number of elements.
     size_type Length;
 
+    /// \brief A dummy "optional" type that is only created by implicit
+    /// conversion from a reference to T.
+    ///
+    /// This type must *only* be used in a function argument or as a copy of
+    /// a function argument, as otherwise it will hold a pointer to a temporary
+    /// past that temporaries' lifetime.
+    struct TRefOrNothing {
+      const T *TPtr;
+
+      TRefOrNothing() : TPtr(nullptr) {}
+      TRefOrNothing(const T &TRef) : TPtr(&TRef) {}
+    };
+
   public:
     /// @name Constructors
     /// @{
@@ -176,6 +190,47 @@ namespace llvm {
     }
 
     /// @}
+    /// @{
+    /// @name Convenience methods
+
+    /// @brief Predicate for testing that the array equals the exact sequence of
+    /// arguments.
+    ///
+    /// Will return false if the size is not equal to the exact number of
+    /// arguments given or if the array elements don't equal the argument
+    /// elements in order. Currently supports up to 16 arguments, but can
+    /// easily be extended.
+    bool equals(TRefOrNothing Arg0 = TRefOrNothing(),
+                TRefOrNothing Arg1 = TRefOrNothing(),
+                TRefOrNothing Arg2 = TRefOrNothing(),
+                TRefOrNothing Arg3 = TRefOrNothing(),
+                TRefOrNothing Arg4 = TRefOrNothing(),
+                TRefOrNothing Arg5 = TRefOrNothing(),
+                TRefOrNothing Arg6 = TRefOrNothing(),
+                TRefOrNothing Arg7 = TRefOrNothing(),
+                TRefOrNothing Arg8 = TRefOrNothing(),
+                TRefOrNothing Arg9 = TRefOrNothing(),
+                TRefOrNothing Arg10 = TRefOrNothing(),
+                TRefOrNothing Arg11 = TRefOrNothing(),
+                TRefOrNothing Arg12 = TRefOrNothing(),
+                TRefOrNothing Arg13 = TRefOrNothing(),
+                TRefOrNothing Arg14 = TRefOrNothing(),
+                TRefOrNothing Arg15 = TRefOrNothing()) {
+      TRefOrNothing Args[] = {Arg0,  Arg1,  Arg2,  Arg3, Arg4,  Arg5,
+                              Arg6,  Arg7,  Arg8,  Arg9, Arg10, Arg11,
+                              Arg12, Arg13, Arg14, Arg15};
+      if (size() > array_lengthof(Args))
+        return false;
+
+      for (unsigned i = 0, e = size(); i != e; ++i)
+        if (Args[i].TPtr == nullptr || (*this)[i] != *Args[i].TPtr)
+          return false;
+
+      // Either the size is exactly as many args, or the next arg must be null.
+      return size() == array_lengthof(Args) || Args[size()].TPtr == nullptr;
+    }
+
+    /// @}
   };
 
   /// MutableArrayRef - Represent a mutable reference to an array (0 or more
diff --git a/llvm/unittests/ADT/ArrayRefTest.cpp b/llvm/unittests/ADT/ArrayRefTest.cpp
index 293afc6ea37..83a012d0cb1 100644
--- a/llvm/unittests/ADT/ArrayRefTest.cpp
+++ b/llvm/unittests/ADT/ArrayRefTest.cpp
@@ -36,5 +36,27 @@ TEST(ArrayRefTest, DropBack) {
   EXPECT_TRUE(AR1.drop_back().equals(AR2));
 }
 
+TEST(ArrayRefTest, Equals) {
+  static const int A1[] = {1, 2, 3, 4, 5, 6, 7, 8};
+  ArrayRef<int> AR1(A1);
+  EXPECT_TRUE(AR1.equals(1, 2, 3, 4, 5, 6, 7, 8));
+  EXPECT_FALSE(AR1.equals(8, 1, 2, 4, 5, 6, 6, 7));
+  EXPECT_FALSE(AR1.equals(2, 4, 5, 6, 6, 7, 8, 1));
+  EXPECT_FALSE(AR1.equals(0, 1, 2, 4, 5, 6, 6, 7));
+  EXPECT_FALSE(AR1.equals(1, 2, 42, 4, 5, 6, 7, 8));
+  EXPECT_FALSE(AR1.equals(42, 2, 3, 4, 5, 6, 7, 8));
+  EXPECT_FALSE(AR1.equals(1, 2, 3, 4, 5, 6, 7, 42));
+  EXPECT_FALSE(AR1.equals(1, 2, 3, 4, 5, 6, 7));
+  EXPECT_FALSE(AR1.equals(1, 2, 3, 4, 5, 6, 7, 8, 9));
+
+  ArrayRef<int> AR1a = AR1.drop_back();
+  EXPECT_TRUE(AR1a.equals(1, 2, 3, 4, 5, 6, 7));
+  EXPECT_FALSE(AR1a.equals(1, 2, 3, 4, 5, 6, 7, 8));
+
+  ArrayRef<int> AR1b = AR1a.slice(2, 4);
+  EXPECT_TRUE(AR1b.equals(3, 4, 5, 6));
+  EXPECT_FALSE(AR1b.equals(2, 3, 4, 5, 6));
+  EXPECT_FALSE(AR1b.equals(3, 4, 5, 6, 7));
+}
 
 } // end anonymous namespace