Faster IndexOf for substrings

THIRD-PARTY-NOTICES.TXT

@@ -697,6 +697,35 @@ License for fastmod (https://github.com/lemire/fastmod) and ibm-fpgen (https://g
    See the License for the specific language governing permissions and
    limitations under the License.
 
+License for sse4-strstr (https://github.com/WojciechMula/sse4-strstr)
+--------------------------------------
+
+   Copyright (c) 2008-2016, Wojciech Muła
+   All rights reserved.
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are
+   met:
+
+   1. Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+   2. Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+   IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+   TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+   PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+   HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+   TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 License notice for The C++ REST SDK
 -----------------------------------
 

src/libraries/System.Memory/tests/Span/IndexOfSequence.char.cs

@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Xunit;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
 
 namespace System.SpanTests
 {
@@ -115,5 +117,104 @@ public static void IndexOfSequenceLengthOneValueJustPasttVeryEnd_Char()
             int index = span.IndexOf(value);
             Assert.Equal(-1, index);
         }
+
+        public static IEnumerable<object[]> IndexOfSubSeqData_Char()
+        {
+            // searchSpace, value, expected IndexOf value, expected LastIndexOf value
+            yield return new object[] { "11111", "111", 0, 2 };
+            yield return new object[] { "1111111111", "1x1", -1, -1 };
+            yield return new object[] { "1111111111", "111", 0, 7 };
+            yield return new object[] { "11111111111x12111", "1x121", 10, 10 };
+            yield return new object[] { "11111111111x12111", "11121", -1, -1 };
+            yield return new object[] { "1111111111x121111", "11121", -1, -1 };
+            yield return new object[] { "11111x12111111111", "11121", -1, -1 };
+            yield return new object[] { "11111111111x12111", "1x211", -1, -1 };
+            yield return new object[] { "11111111111x12111", "11211", -1, -1 };
+            yield return new object[] { "1111111111x121111", "11211", -1, -1 };
+            yield return new object[] { "11111x12111111111", "11211", -1, -1 };
+            yield return new object[] { "11111111111x12111", "12111", 12, 12 };
+            yield return new object[] { "1111111111x121111", "12111", 11, 11 };
+            yield return new object[] { "11111x12111111111", "12111", 6, 6 };
+            yield return new object[] { "1111x1211111111111x12", "11121", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12", "11121", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12", "111121", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12", "1111121", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12", "1111121", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12", "1111121", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12", "1211211", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12", "1211111", 5, 5 };
+            yield return new object[] { "1111x1211111111111x12", "1211111", 5, 5 };
+            yield return new object[] { "1111x1211111111111x12", "1211111", 5, 5 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "111", 0, 44 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "1111", 0, 43 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "11111", 7, 42 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "111111", 7, 41 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "1111111", 7, 11 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "11111111", 7, 10 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "111111111", 7, 9 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "11111111111", 7, 7 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "111111111111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "1111111111111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "11111111111111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "111111111111111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "11111111111111111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "111111111111111111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "1211", 5, 48 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "11121", 44, 44 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "121111", 5, 19 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "12111211", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "1111111", 7, 11 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "1121121111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "1111211111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "111111211111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "1121111111111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "11122111112111111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "1111111211111111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "111211111111111111", -1, -1 };
+            yield return new object[] { "1111x1211111111111x12111122131221221211221111112121121", "11111211111121111111", -1, -1 };
+            yield return new object[] { "жжжжжжжжжжжжжж", "жжж", 0, 11 };
+            yield return new object[] { "жжжжжжжжжжжжжжжжжжжжжжжжжжжж", "ж0ж", -1, -1 };
+            yield return new object[] { "жжжжжаааааааааааааааччччс", "ччччс", 20, 20 };
+            yield return new object[] { "жжжжжаааааааааааааааччччсссссссчччч", "чччч", 20, 31 };
+            yield return new object[] { "жжжжжжжжжжжжжжжжжжжжжжжжжжжж", "1112", -1, -1 };
+            yield return new object[] { "0уза0оцущ0оаз0щцуоазщцуо0азщцуоазщоц0узозцуоазуоцз0щауцз0оазцо", "0оаз0", 9, 9 };
+            yield return new object[] { "abababababababababababababababbc", "bb", 29, 29 };
+            yield return new object[] { "abababababababababababababababb", "bb", 29, 29 };
+            yield return new object[] { "abababababababababababababababbc", "bb", 29, 29 };
+            yield return new object[] { "babababababababababababababababc", "bb", -1, -1 };
+            yield return new object[] { "abababababababababababababababbb", "bbb", 29, 29 };
+            yield return new object[] { "abababababababababababababababbbc", "bbb", 29, 29 };
+            yield return new object[] { "bbbbabababababababababababababababc", "bbb", 0, 1 };
+            yield return new object[] { "abababababababababababababababbc", "aa", -1, -1 };
+            yield return new object[] { "abababababababababababababababb", "aa", -1, -1 };
+            yield return new object[] { "abababababababababababababababbc", "aa", -1, -1 };
+            yield return new object[] { "babababababababababababababababc", "aa", -1, -1 };
+            yield return new object[] { "abababababababababababababababbb", "aaa", -1, -1 };
+            yield return new object[] { "abababababababababababababababbbc", "aaa", -1, -1 };
+            yield return new object[] { "bbbbabababababababababababababababc", "aaa", -1, -1 };
+            yield return new object[] { "ababababababababababababababababbc", "abaa", -1, -1 };
+            yield return new object[] { "babbbabababababababababababababababc", "babb", 0, 0 };
+            yield return new object[] { "babbbabababababababababababababababc", "сaсс", -1, -1 };
+            yield return new object[] { "babbbbbbbbbbbbb", "babbbbbbbbbbbb", 0, 0 };
+            yield return new object[] { "babbbbbbbbbbbbbbabbbbbbbbbbbb", "babbbbbbbbbbbb", 0, 15 };
+            yield return new object[] { "babbbbbbbbbbbbbbbbabbbbbbbbbbbb", "babbbbbbbbbbbb", 0, 17 };
+            yield return new object[] { "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbb", "babbbbbbbbbbbb", 18, 32 };
+            yield return new object[] { "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbb", "bbbbbbbbbbbbb", 20, 20 };
+            yield return new object[] { "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbb", "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbb", 0, 0 };
+            yield return new object[] { "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbb", "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbb", 0, 0 };
+            yield return new object[] { "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbb", "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbbb", -1, -1 };
+            yield return new object[] { "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbb", "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbb", 0, 0 };
+            yield return new object[] { "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbb", "babbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbb", 0, 0 };
+            yield return new object[] { "xxxxxxxxxxxxxxbabbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbbxxxxxxxxxxxxxxx", "xxxxxxxxxxxxxxx", 60, 60 };
+            yield return new object[] { "xxxxxxxxxxxxxxxbabbbbbbxbbbbbbbbbbabbbbbbbbbbbbbabbbbbbbbbbbbxxxxxxxxxxxxxx", "xxxxxxxxxxxxxxx", 0, 0 };
+        }
+
+        [Theory]
+        [MemberData(nameof(IndexOfSubSeqData_Char))]
+        public static void ValueStartsAndEndsWithTheSameChars(string searchSpace, string value, int expectedIndexOfValue, int expectedLastIndexOfValue)
+        {
+            Assert.Equal(expectedIndexOfValue, searchSpace.AsSpan().IndexOf(value));
+            Assert.Equal(expectedLastIndexOfValue, searchSpace.AsSpan().LastIndexOf(value));
+        }
     }
 }

src/libraries/System.Private.CoreLib/src/System/MemoryExtensions.cs

@@ -580,12 +580,25 @@ ref Unsafe.As<T, char>(ref MemoryMarshal.GetReference(span)),
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static int LastIndexOf<T>(this ReadOnlySpan<T> span, ReadOnlySpan<T> value) where T : IEquatable<T>
         {
-            if (Unsafe.SizeOf<T>() == sizeof(byte) && RuntimeHelpers.IsBitwiseEquatable<T>())
-                return SpanHelpers.LastIndexOf(
-                    ref Unsafe.As<T, byte>(ref MemoryMarshal.GetReference(span)),
-                    span.Length,
-                    ref Unsafe.As<T, byte>(ref MemoryMarshal.GetReference(value)),
-                    value.Length);
+            if (RuntimeHelpers.IsBitwiseEquatable<T>())
+            {
+                if (Unsafe.SizeOf<T>() == sizeof(byte))
+                {
+                    return SpanHelpers.LastIndexOf(
+                        ref Unsafe.As<T, byte>(ref MemoryMarshal.GetReference(span)),
+                        span.Length,
+                        ref Unsafe.As<T, byte>(ref MemoryMarshal.GetReference(value)),
+                        value.Length);
+                }
+                if (Unsafe.SizeOf<T>() == sizeof(char))
+                {
+                    return SpanHelpers.LastIndexOf(
+                        ref Unsafe.As<T, char>(ref MemoryMarshal.GetReference(span)),
+                        span.Length,
+                        ref Unsafe.As<T, char>(ref MemoryMarshal.GetReference(value)),
+                        value.Length);
+                }
+            }
 
             return SpanHelpers.LastIndexOf<T>(ref MemoryMarshal.GetReference(span), span.Length, ref MemoryMarshal.GetReference(value), value.Length);
         }

src/libraries/System.Private.CoreLib/src/System/Numerics/BitOperations.cs

@@ -708,5 +708,25 @@ public static nuint RotateRight(nuint value, int offset)
             return (nuint)RotateRight((uint)value, offset);
 #endif
         }
+
+        /// <summary>
+        /// Reset the lowest significant bit in the given value
+        /// </summary>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static uint ResetLowestSetBit(uint value)
+        {
+            // It's lowered to BLSR on x86
+            return value & (value - 1);
+        }
+
+        /// <summary>
+        /// Reset specific bit in the given value
+        /// </summary>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static uint ResetBit(uint value, int bitPos)
+        {
+            // TODO: Recognize BTR on x86 and LSL+BIC on ARM
+            return value & ~(uint)(1 << bitPos);
+        }
     }
 }