Test fix

src/coreclr/jit/codegenarmarch.cpp

@@ -1508,7 +1508,7 @@ void CodeGen::genCodeForNullCheck(GenTreeIndir* tree)
     genConsumeRegs(op1);
     regNumber targetReg = REG_ZR;
 
-    GetEmitter()->emitInsLoadStoreOp(INS_ldr, EA_4BYTE, targetReg, tree);
+    GetEmitter()->emitInsLoadStoreOp(ins_Load(tree->TypeGet()), emitActualTypeSize(tree), targetReg, tree);
 #endif
 }
 

src/coreclr/jit/compiler.cpp

@@ -9735,7 +9735,6 @@ void Compiler::gtChangeOperToNullCheck(GenTree* tree, BasicBlock* block)
 {
     assert(tree->OperIs(GT_FIELD, GT_IND, GT_OBJ, GT_BLK));
     tree->ChangeOper(GT_NULLCHECK);
-    tree->ChangeType(TYP_INT);
     block->bbFlags |= BBF_HAS_NULLCHECK;
     optMethodFlags |= OMF_HAS_NULLCHECK;
 }

src/coreclr/jit/emitarm64.cpp

@@ -6993,13 +6993,6 @@ void emitter::emitIns_R_R_R_Ext(instruction ins,
         shiftAmount = insOptsLSL(opt) ? scale : 0;
     }
 
-    // If target reg is ZR - it means we're doing an implicit nullcheck
-    // where target type was ignored and set to TYP_INT.
-    if ((reg1 == REG_ZR) && (shiftAmount > 0))
-    {
-        shiftAmount = scale;
-    }
-
     assert((shiftAmount == scale) || (shiftAmount == 0));
 
     reg2 = encodingSPtoZR(reg2);

src/coreclr/jit/lower.cpp

@@ -6855,7 +6855,6 @@ void Lowering::TransformUnusedIndirection(GenTreeIndir* ind, Compiler* comp, Bas
     //
     assert(ind->OperIs(GT_NULLCHECK, GT_IND, GT_BLK, GT_OBJ));
 
-    ind->gtType = TYP_INT;
 #ifdef TARGET_ARM64
     bool useNullCheck = true;
 #elif TARGET_ARM

src/tests/JIT/Regression/JitBlue/Runtime_64657/Runtime_64657.cs

@@ -0,0 +1,42 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Runtime.InteropServices;
+using System.Runtime.CompilerServices;
+
+public class Runtime_64657
+{
+    [DllImport("kernel32")]
+    public static extern byte* VirtualAlloc(IntPtr lpAddress, nuint dwSize, uint flAllocationType, uint flProtect);
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    static void Validate<T>(T* c, int x) where T : unmanaged
+    {
+        // this nullcheck should not read more than requested
+        T implicitNullcheck = c[x];
+    }
+
+    public static int Main()
+    {
+        if (!OperatingSystem.IsWindows())
+            return 100; // VirtualAlloc is only for Windows
+
+        uint length = (uint)Environment.SystemPageSize;
+        byte* ptr = VirtualAlloc(IntPtr.Zero, length, 0x1000 | 0x2000 /* reserve commit */, 0x04 /*readonly guard*/);
+
+        Validate((byte*)(ptr + length - sizeof(byte)), 0);
+        Validate((sbyte*)(ptr + length - sizeof(sbyte)), 0);
+        Validate((bool*)(ptr + length - sizeof(bool)), 0);
+        Validate((ushort*)(ptr + length - sizeof(ushort)), 0);
+        Validate((short*)(ptr + length - sizeof(short)), 0);
+        Validate((uint*)(ptr + length - sizeof(uint)), 0);
+        Validate((int*)(ptr + length - sizeof(int)), 0);
+        Validate((ulong*)(ptr + length - sizeof(ulong)), 0);
+        Validate((long*)(ptr + length - sizeof(long)), 0);
+        Validate((nint*)(ptr + length - sizeof(nint)), 0);
+        Validate((nuint*)(ptr + length - sizeof(nuint)), 0);
+
+        return 100;
+    }
+}

src/tests/JIT/Regression/JitBlue/Runtime_64657/Runtime_64657.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+</Project>