From 7dbf6a5f2fd636db350f9cc31b2dfd3af0eff1a8 Mon Sep 17 00:00:00 2001
From: Egor Bogatov <egorbo@gmail.com>
Date: Mon, 17 Apr 2023 15:54:35 +0200
Subject: [PATCH] Improve SeqEquals shape (#84524)

---
 .../src/System/MemoryExtensions.cs                | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/libraries/System.Private.CoreLib/src/System/MemoryExtensions.cs b/src/libraries/System.Private.CoreLib/src/System/MemoryExtensions.cs
index bdeebbf560b7c..d12bf4f4fae0e 100644
--- a/src/libraries/System.Private.CoreLib/src/System/MemoryExtensions.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/MemoryExtensions.cs
@@ -1426,17 +1426,18 @@ private static void ThrowNullLowHighInclusive<T>(T? lowInclusive, T? highInclusi
         public static unsafe bool SequenceEqual<T>(this Span<T> span, ReadOnlySpan<T> other) where T : IEquatable<T>?
         {
             int length = span.Length;
+            int otherLength = other.Length;
 
             if (RuntimeHelpers.IsBitwiseEquatable<T>())
             {
-                return length == other.Length &&
+                return length == otherLength &&
                 SpanHelpers.SequenceEqual(
                     ref Unsafe.As<T, byte>(ref MemoryMarshal.GetReference(span)),
                     ref Unsafe.As<T, byte>(ref MemoryMarshal.GetReference(other)),
-                    ((uint)length) * (nuint)sizeof(T));  // If this multiplication overflows, the Span we got overflows the entire address range. There's no happy outcome for this api in such a case so we choose not to take the overhead of checking.
+                    ((uint)otherLength) * (nuint)sizeof(T));  // If this multiplication overflows, the Span we got overflows the entire address range. There's no happy outcome for this api in such a case so we choose not to take the overhead of checking.
             }
 
-            return length == other.Length && SpanHelpers.SequenceEqual(ref MemoryMarshal.GetReference(span), ref MemoryMarshal.GetReference(other), length);
+            return length == otherLength && SpanHelpers.SequenceEqual(ref MemoryMarshal.GetReference(span), ref MemoryMarshal.GetReference(other), length);
         }
 
         /// <summary>
@@ -2161,16 +2162,18 @@ public static int LastIndexOfAny<T>(this ReadOnlySpan<T> span, IndexOfAnyValues<
         public static unsafe bool SequenceEqual<T>(this ReadOnlySpan<T> span, ReadOnlySpan<T> other) where T : IEquatable<T>?
         {
             int length = span.Length;
+            int otherLength = other.Length;
+
             if (RuntimeHelpers.IsBitwiseEquatable<T>())
             {
-                return length == other.Length &&
+                return length == otherLength &&
                     SpanHelpers.SequenceEqual(
                         ref Unsafe.As<T, byte>(ref MemoryMarshal.GetReference(span)),
                         ref Unsafe.As<T, byte>(ref MemoryMarshal.GetReference(other)),
-                        ((uint)length) * (nuint)sizeof(T));  // If this multiplication overflows, the Span we got overflows the entire address range. There's no happy outcome for this API in such a case so we choose not to take the overhead of checking.
+                        ((uint)otherLength) * (nuint)sizeof(T));  // If this multiplication overflows, the Span we got overflows the entire address range. There's no happy outcome for this API in such a case so we choose not to take the overhead of checking.
             }
 
-            return length == other.Length && SpanHelpers.SequenceEqual(ref MemoryMarshal.GetReference(span), ref MemoryMarshal.GetReference(other), length);
+            return length == otherLength && SpanHelpers.SequenceEqual(ref MemoryMarshal.GetReference(span), ref MemoryMarshal.GetReference(other), length);
         }
 
         /// <summary>