Add a benchmark to test comparing equal strings

Author: aschwaighofer

benchmark/single-source/StringTests.swift

@@ -65,3 +65,20 @@ public func run_StringHasSuffixUnicode(_ N: Int) {
     }
   }
 }
+
+@inline(never)
+internal func compareEqual(_ str1: String, _ str2: String) -> Bool {
+  return str1 == str2
+}
+
+public func run_StringEqualPointerComparison(_ N: Int) {
+  let str1 = "The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. "
+  let str2 = str1
+  for _ in 0 ..< N {
+    for _ in 0 ..< 100_000 {
+      if !compareEqual(str1, str2) {
+        CheckResults(false, "Strings should be equal")
+      }
+    }
+  }
+}

benchmark/utils/main.swift

@@ -205,6 +205,7 @@ precommitTests = [
   "StrComplexWalk": run_StrComplexWalk,
   "StrToInt": run_StrToInt,
   "StringBuilder": run_StringBuilder,
+  "StringEqualPointerComparison": run_StringEqualPointerComparison,
   "StringInterpolation": run_StringInterpolation,
   "StringHasPrefix": run_StringHasPrefix,
   "StringHasPrefixUnicode": run_StringHasPrefixUnicode,