From f40173de7b43f9014aadd33f46a8a170fb8aa05c Mon Sep 17 00:00:00 2001
From: Filip Navara <filip.navara@gmail.com>
Date: Sat, 3 Feb 2024 12:13:44 +0100
Subject: [PATCH 1/2] Mark unaligned reads in NativeFormatReader as unaligned
 for the JIT

---
 .../src/System/Runtime/CompilerServices/Unsafe.cs      | 10 ++++++++++
 .../NativeFormat/NativeFormatReader.Primitives.cs      |  7 ++++---
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/CompilerServices/Unsafe.cs b/src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/CompilerServices/Unsafe.cs
index 7c77d12b7cc38..d45340d22d0d9 100644
--- a/src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/CompilerServices/Unsafe.cs
+++ b/src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/CompilerServices/Unsafe.cs
@@ -109,5 +109,15 @@ public static ref T AsRef<T>(in T source)
         {
             throw new PlatformNotSupportedException();
         }
+
+        /// <summary>
+        /// Reads a value of type <typeparamref name="T"/> from the given location.
+        /// </summary>
+        [Intrinsic]
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static T ReadUnaligned<T>(ref readonly byte source)
+        {
+            throw new PlatformNotSupportedException();
+        }
     }
 }
diff --git a/src/coreclr/tools/Common/Internal/NativeFormat/NativeFormatReader.Primitives.cs b/src/coreclr/tools/Common/Internal/NativeFormat/NativeFormatReader.Primitives.cs
index 7f7a8ebdcec53..0b979008f5ee6 100644
--- a/src/coreclr/tools/Common/Internal/NativeFormat/NativeFormatReader.Primitives.cs
+++ b/src/coreclr/tools/Common/Internal/NativeFormat/NativeFormatReader.Primitives.cs
@@ -8,6 +8,7 @@
 // ---------------------------------------------------------------------------
 
 using System.Diagnostics;
+using System.Runtime.CompilerServices;
 
 namespace Internal.NativeFormat
 {
@@ -23,21 +24,21 @@ public static byte ReadUInt8(ref byte* stream)
 
         public static ushort ReadUInt16(ref byte* stream)
         {
-            ushort result = *(ushort*)(stream); // Assumes little endian and unaligned access
+            ushort result = Unsafe.ReadUnaligned<ushort>(ref *stream); // Assumes little endian and unaligned access
             stream += 2;
             return result;
         }
 
         public static uint ReadUInt32(ref byte* stream)
         {
-            uint result = *(uint*)(stream); // Assumes little endian and unaligned access
+            uint result = Unsafe.ReadUnaligned<uint>(ref *stream); // Assumes little endian and unaligned access
             stream += 4;
             return result;
         }
 
         public static ulong ReadUInt64(ref byte* stream)
         {
-            ulong result = *(ulong*)(stream); // Assumes little endian and unaligned access
+            ulong result = Unsafe.ReadUnaligned<ulong>(ref *stream); // Assumes little endian and unaligned access
             stream += 8;
             return result;
         }

From 972ca8e64bc948f65cbf80c50f46b7937e7a7770 Mon Sep 17 00:00:00 2001
From: Filip Navara <filip.navara@gmail.com>
Date: Sat, 3 Feb 2024 12:43:27 +0100
Subject: [PATCH 2/2] Better fix

---
 .../src/System/Runtime/CompilerServices/Unsafe.cs           | 2 +-
 .../Internal/NativeFormat/NativeFormatReader.Primitives.cs  | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/CompilerServices/Unsafe.cs b/src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/CompilerServices/Unsafe.cs
index d45340d22d0d9..136872edd4a47 100644
--- a/src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/CompilerServices/Unsafe.cs
+++ b/src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/CompilerServices/Unsafe.cs
@@ -115,7 +115,7 @@ public static ref T AsRef<T>(in T source)
         /// </summary>
         [Intrinsic]
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static T ReadUnaligned<T>(ref readonly byte source)
+        public static T ReadUnaligned<T>(void* source)
         {
             throw new PlatformNotSupportedException();
         }
diff --git a/src/coreclr/tools/Common/Internal/NativeFormat/NativeFormatReader.Primitives.cs b/src/coreclr/tools/Common/Internal/NativeFormat/NativeFormatReader.Primitives.cs
index 0b979008f5ee6..b0d0551735562 100644
--- a/src/coreclr/tools/Common/Internal/NativeFormat/NativeFormatReader.Primitives.cs
+++ b/src/coreclr/tools/Common/Internal/NativeFormat/NativeFormatReader.Primitives.cs
@@ -24,21 +24,21 @@ public static byte ReadUInt8(ref byte* stream)
 
         public static ushort ReadUInt16(ref byte* stream)
         {
-            ushort result = Unsafe.ReadUnaligned<ushort>(ref *stream); // Assumes little endian and unaligned access
+            ushort result = Unsafe.ReadUnaligned<ushort>(stream); // Assumes little endian and unaligned access
             stream += 2;
             return result;
         }
 
         public static uint ReadUInt32(ref byte* stream)
         {
-            uint result = Unsafe.ReadUnaligned<uint>(ref *stream); // Assumes little endian and unaligned access
+            uint result = Unsafe.ReadUnaligned<uint>(stream); // Assumes little endian and unaligned access
             stream += 4;
             return result;
         }
 
         public static ulong ReadUInt64(ref byte* stream)
         {
-            ulong result = Unsafe.ReadUnaligned<ulong>(ref *stream); // Assumes little endian and unaligned access
+            ulong result = Unsafe.ReadUnaligned<ulong>(stream); // Assumes little endian and unaligned access
             stream += 8;
             return result;
         }