Merge pull request dotnet#1063 from bbowyersmyth/StringEquals

Improve String.Equals loop body performance
MichalStrehovsky · Mar 28, 2016 · 332d6cc · 332d6cc
2 parents 07ad288 + fa6da30
commit 332d6cc
Showing 1 changed file with 16 additions and 20 deletions.
diff --git a/src/System.Private.CoreLib/src/System/String.cs b/src/System.Private.CoreLib/src/System/String.cs
@@ -699,19 +699,19 @@ private unsafe static bool OrdinalCompareEqualLengthStrings(String strA, String
 
                 while (length >= 12)
                 {
-                    if (*(long*)a != *(long*)b) return false;
-                    if (*(long*)(a + 4) != *(long*)(b + 4)) return false;
-                    if (*(long*)(a + 8) != *(long*)(b + 8)) return false;
+                    if (*(long*)a != *(long*)b) goto ReturnFalse;
+                    if (*(long*)(a + 4) != *(long*)(b + 4)) goto ReturnFalse;
+                    if (*(long*)(a + 8) != *(long*)(b + 8)) goto ReturnFalse;
                     length -= 12; a += 12; b += 12;
                 }
 #else
                 while (length >= 10)
                 {
-                    if (*(int*)a != *(int*)b) return false;
-                    if (*(int*)(a + 2) != *(int*)(b + 2)) return false;
-                    if (*(int*)(a + 4) != *(int*)(b + 4)) return false;
-                    if (*(int*)(a + 6) != *(int*)(b + 6)) return false;
-                    if (*(int*)(a + 8) != *(int*)(b + 8)) return false;
+                    if (*(int*)a != *(int*)b) goto ReturnFalse;
+                    if (*(int*)(a + 2) != *(int*)(b + 2)) goto ReturnFalse;
+                    if (*(int*)(a + 4) != *(int*)(b + 4)) goto ReturnFalse;
+                    if (*(int*)(a + 6) != *(int*)(b + 6)) goto ReturnFalse;
+                    if (*(int*)(a + 8) != *(int*)(b + 8)) goto ReturnFalse;
                     length -= 10; a += 10; b += 10;
                 }
 #endif
@@ -722,11 +722,14 @@ private unsafe static bool OrdinalCompareEqualLengthStrings(String strA, String
                 // the zero terminator.
                 while (length > 0)
                 {
-                    if (*(int*)a != *(int*)b) break;
+                    if (*(int*)a != *(int*)b) goto ReturnFalse;
                     length -= 2; a += 2; b += 2;
                 }
 
-                return (length <= 0);
+                return true;
+
+                ReturnFalse:
+                return false;
             }
         }
 
@@ -965,14 +968,11 @@ public static bool Equals(String a, String b)
                 return true;
             }
 
-            if ((Object)a == null || (Object)b == null)
+            if ((Object)a == null || (Object)b == null || a.Length != b.Length)
             {
                 return false;
             }
 
-            if (a.Length != b.Length)
-                return false;
-
             return OrdinalCompareEqualLengthStrings(a, b);
         }
 
@@ -1020,9 +1020,7 @@ public static bool Equals(String a, String b, StringComparison comparisonType)
         {
             if (Object.ReferenceEquals(a, b))
                 return true;
-            if (a == null || b == null)
-                return false;
-            if (a.Length != b.Length)
+            if (a == null || b == null || a.Length != b.Length)
                 return false;
             return OrdinalCompareEqualLengthStrings(a, b);
         }
@@ -1031,9 +1029,7 @@ public static bool Equals(String a, String b, StringComparison comparisonType)
         {
             if (Object.ReferenceEquals(a, b))
                 return false;
-            if (a == null || b == null)
-                return true;
-            if (a.Length != b.Length)
+            if (a == null || b == null || a.Length != b.Length)
                 return true;
             return !OrdinalCompareEqualLengthStrings(a, b);
         }