Surgical fix for bad assertion generation

src/coreclr/jit/assertionprop.cpp

@@ -1271,6 +1271,10 @@ AssertionIndex Compiler::optCreateAssertion(GenTree*         op1,
                     }
 
                     toType = op2->CastToType();
+                    if (toType == TYP_UINT)
+                    {
+                        toType = TYP_INT;
+                    }
                 SUBRANGE_COMMON:
                     if ((assertionKind != OAK_SUBRANGE) && (assertionKind != OAK_EQUAL))
                     {

src/tests/JIT/Regression/JitBlue/Runtime_54842/Runtime_54842.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Runtime.CompilerServices;
+
+public class Runtime_54842
+{
+    public static int Main()
+    {
+        try
+        {
+            DoubleCheckedConvert(uint.MaxValue);
+        }
+        catch (OverflowException)
+        {
+            return 100;
+        }
+
+        return 101;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static uint DoubleCheckedConvert(ulong a)
+    {
+        var b = (int)checked((uint)a);
+
+        // Make sure the importer spills "b" to a local.
+        Use(b);
+
+        return checked((uint)b);
+    }
+
+    private static void Use(int value) { }
+}

src/tests/JIT/Regression/JitBlue/Runtime_54842/Runtime_54842.csproj

@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+  </PropertyGroup>
+  <PropertyGroup>
+    <DebugType>None</DebugType>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+</Project>