Check for cannonicalization of shl X, 1 -> add X, X

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3670 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/shift.ll

@@ -33,3 +33,7 @@ uint "test5"(uint %A) {
 	ret uint %B
 }
 
+uint %test6(uint %A) {
+	%B = shl uint %A, ubyte 1   ;; convert to an add instruction
+	ret uint %B
+}