[release/8.0-staging] Fix Vector512.CopyTo (#95026)

* Fix Vector512.CopyTo

* Also unify Vector

* Handle float vectors too

* Fix legacy vectors

* Simplify the change

* Update Vector_1.cs

* Add tests

* Fix build

---------

Co-authored-by: Michał Petryka <[email protected]>

Author: github-actions[bot]

src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector512.cs

@@ -441,8 +441,7 @@ public static void CopyTo<T>(this Vector512<T> vector, T[] destination)
                 ThrowHelper.ThrowArgumentException_DestinationTooShort();
             }
 
-            ref byte address = ref Unsafe.As<T, byte>(ref MemoryMarshal.GetArrayDataReference(destination));
-            Unsafe.WriteUnaligned(ref address, vector);
+            Unsafe.WriteUnaligned(ref Unsafe.As<T, byte>(ref destination[0]), vector);
         }
 
         /// <summary>Copies a <see cref="Vector512{T}" /> to a given array starting at the specified index.</summary>
@@ -468,8 +467,7 @@ public static void CopyTo<T>(this Vector512<T> vector, T[] destination, int star
                 ThrowHelper.ThrowArgumentException_DestinationTooShort();
             }
 
-            ref byte address = ref Unsafe.As<T, byte>(ref MemoryMarshal.GetArrayDataReference(destination));
-            Unsafe.WriteUnaligned(ref Unsafe.Add(ref address, startIndex), vector);
+            Unsafe.WriteUnaligned(ref Unsafe.As<T, byte>(ref destination[startIndex]), vector);
         }
 
         /// <summary>Copies a <see cref="Vector512{T}" /> to a given span.</summary>

src/libraries/System.Runtime.Intrinsics/tests/Vectors/Vector128Tests.cs

@@ -4517,6 +4517,22 @@ public void Vector128SingleEqualsNonCanonicalNaNTest()
             }
         }
 
+        [Fact]
+        public void Vector128SingleCopyToTest()
+        {
+            float[] array = new float[4];
+            Vector128.Create(2.0f).CopyTo(array);
+            Assert.True(array.AsSpan().SequenceEqual([2.0f, 2.0f, 2.0f, 2.0f]));
+        }
+
+        [Fact]
+        public void Vector128SingleCopyToOffsetTest()
+        {
+            float[] array = new float[5];
+            Vector128.Create(2.0f).CopyTo(array, 1);
+            Assert.True(array.AsSpan().SequenceEqual([0.0f, 2.0f, 2.0f, 2.0f, 2.0f]));
+        }
+
         [Fact]
         public void IsSupportedByte() => TestIsSupported<byte>();
 

src/libraries/System.Runtime.Intrinsics/tests/Vectors/Vector256Tests.cs

@@ -5539,6 +5539,22 @@ public void Vector256SingleEqualsNonCanonicalNaNTest()
             }
         }
 
+        [Fact]
+        public void Vector256SingleCopyToTest()
+        {
+            float[] array = new float[8];
+            Vector256.Create(2.0f).CopyTo(array);
+            Assert.True(array.AsSpan().SequenceEqual([2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f]));
+        }
+
+        [Fact]
+        public void Vector256SingleCopyToOffsetTest()
+        {
+            float[] array = new float[9];
+            Vector256.Create(2.0f).CopyTo(array, 1);
+            Assert.True(array.AsSpan().SequenceEqual([0.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f]));
+        }
+
         [Fact]
         public void IsSupportedByte() => TestIsSupported<byte>();
 

src/libraries/System.Runtime.Intrinsics/tests/Vectors/Vector512Tests.cs

@@ -5016,6 +5016,22 @@ public void Vector512SingleEqualsNonCanonicalNaNTest()
             }
         }
 
+        [Fact]
+        public void Vector512SingleCopyToTest()
+        {
+            float[] array = new float[16];
+            Vector512.Create(2.0f).CopyTo(array);
+            Assert.True(array.AsSpan().SequenceEqual([2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f]));
+        }
+
+        [Fact]
+        public void Vector512SingleCopyToOffsetTest()
+        {
+            float[] array = new float[17];
+            Vector512.Create(2.0f).CopyTo(array, 1);
+            Assert.True(array.AsSpan().SequenceEqual([0.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f, 2.0f]));
+        }
+
         [Fact]
         public void IsSupportedByte() => TestIsSupported<byte>();
 

src/libraries/System.Runtime.Intrinsics/tests/Vectors/Vector64Tests.cs

@@ -3937,6 +3937,22 @@ public void Vector64SingleEqualsNonCanonicalNaNTest()
             }
         }
 
+        [Fact]
+        public void Vector64SingleCopyToTest()
+        {
+            float[] array = new float[2];
+            Vector64.Create(2.0f).CopyTo(array);
+            Assert.True(array.AsSpan().SequenceEqual([2.0f, 2.0f]));
+        }
+
+        [Fact]
+        public void Vector64SingleCopyToOffsetTest()
+        {
+            float[] array = new float[3];
+            Vector64.Create(2.0f).CopyTo(array, 1);
+            Assert.True(array.AsSpan().SequenceEqual([0.0f, 2.0f, 2.0f]));
+        }
+
         [Fact]
         public void IsSupportedByte() => TestIsSupported<byte>();