From 94abb3c9658484946488e822233cb01edaa95910 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Mon, 20 Apr 2026 19:34:00 +0000
Subject: [PATCH 1/2] Initial plan


From 70d2be2ab0ff33f141c5864c5b33c335b49fef06 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Mon, 20 Apr 2026 19:39:16 +0000
Subject: [PATCH 2/2] Fix unsigned modulo opcode emission

Agent-Logs-Url: https://github.com/dadhi/FastExpressionCompiler/sessions/186dbd9c-2730-47f1-b5c7-fb8800c10d05

Co-authored-by: dadhi <39516+dadhi@users.noreply.github.com>
---
 .../FastExpressionCompiler.cs                 |  2 +-
 .../ArithmeticOperationsTests.cs              | 29 ++++++++++++++++++-
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/FastExpressionCompiler/FastExpressionCompiler.cs b/src/FastExpressionCompiler/FastExpressionCompiler.cs
index 7780f141..53fdbf17 100644
--- a/src/FastExpressionCompiler/FastExpressionCompiler.cs
+++ b/src/FastExpressionCompiler/FastExpressionCompiler.cs
@@ -5929,7 +5929,7 @@ private static bool TryEmitArithmeticOperation(Type leftType, Type rightType, Ex
                     ExpressionType.Multiply => OpCodes.Mul,
                     ExpressionType.MultiplyChecked => exprType.IsUnsigned() ? OpCodes.Mul_Ovf_Un : OpCodes.Mul_Ovf,
                     ExpressionType.Divide => OpCodes.Div,
-                    ExpressionType.Modulo => OpCodes.Rem,
+                    ExpressionType.Modulo => exprType.IsUnsigned() ? OpCodes.Rem_Un : OpCodes.Rem,
                     ExpressionType.And => OpCodes.And,
                     ExpressionType.Or => OpCodes.Or,
                     ExpressionType.ExclusiveOr => OpCodes.Xor,
diff --git a/test/FastExpressionCompiler.UnitTests/ArithmeticOperationsTests.cs b/test/FastExpressionCompiler.UnitTests/ArithmeticOperationsTests.cs
index 1883430a..b6554942 100644
--- a/test/FastExpressionCompiler.UnitTests/ArithmeticOperationsTests.cs
+++ b/test/FastExpressionCompiler.UnitTests/ArithmeticOperationsTests.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Numerics;
+using System.Reflection.Emit;
 
 #if LIGHT_EXPRESSION
 using static FastExpressionCompiler.LightExpression.Expression;
@@ -18,6 +19,7 @@ public int Run()
             Can_modulus_custom_in_Action();
             Can_add_string_and_not_string();
             Can_modulus_custom();
+            Can_modulus_with_unsigned_block_local_variable();
             Can_sum_bytes_converted_to_ints();
             Can_sum_signed_bytes_converted_to_ints();
             Can_sum_all_primitive_numeric_types_that_define_binary_operator_add();
@@ -47,7 +49,7 @@ public int Run()
             Can_calculate_arithmetic_operation_with_vectors();
             Can_add_strings();
 
-            return 29;
+            return 30;
         }
 
         public void Can_sum_bytes_converted_to_ints()
@@ -229,6 +231,31 @@ public void Can_modulus()
             Asserts.AreEqual(1, f(7, 6));
         }
 
+        public void Can_modulus_with_unsigned_block_local_variable()
+        {
+            var b = Parameter(typeof(uint), "b");
+            var a = Variable(typeof(uint), "a");
+            var expr = Lambda<Func<uint, uint>>(
+                Block(new[] { a },
+                    Assign(a, Constant(0x80000000u)),
+                    Modulo(a, b)),
+                b);
+
+            var fs = expr.CompileSys();
+            var ff = expr.CompileFast(true, CompilerFlags.EnableDelegateDebugInfo);
+
+            Asserts.AreEqual(2u, fs(3u));
+            Asserts.AreEqual(2u, ff(3u));
+            ff.AssertOpCodes(
+                OpCodes.Ldc_I4,
+                OpCodes.Stloc_0,
+                OpCodes.Ldloc_0,
+                OpCodes.Ldarg_1,
+                OpCodes.Rem_Un,
+                OpCodes.Ret
+            );
+        }
+
 
         public void Can_bit_or_1()
         {