JIT incorrectly reorders constrained call 'this' indirections with other arguments

[jakobbotsch]

Small example:

using InlineIL;
using System;
using System.Runtime.CompilerServices;

public class Program
{
 public static void Main()
 {
 Foo(new C("A"));
 }

 [MethodImpl(MethodImplOptions.NoInlining)]
 private static void Foo(C arg)
 {
 IL.Emit.Ldarga(nameof(arg));
 IL.Emit.Ldarga(nameof(arg));
 IL.Emit.Call(new MethodRef(typeof(Program), nameof(Bar)));
 IL.Emit.Constrained<C>();
 IL.Emit.Callvirt(new MethodRef(typeof(C), nameof(arg.Baz)));
 }

 [MethodImpl(MethodImplOptions.NoInlining)]
 private static int Bar(ref C o)
 {
 o = new C("B");
 return 0;
 }
}

public record class C(string Name)
{
 public void Baz(int arg)
 {
 Console.WriteLine(Name);
 }
}

Expected: B
Actual: A

Seen in #73606 (comment)

category:correctness
theme:importer
skill-level:intermediate
cost:small
impact:small

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Issue Details

---

Small example:

using InlineIL;
using System;

public class Program
{
 public static void Main()
 {
 Foo(new C("A"));
 }

 private static void Foo(C arg)
 {
 IL.Emit.Ldarga(nameof(arg));
 IL.Emit.Ldarga(nameof(arg));
 IL.Emit.Call(new MethodRef(typeof(Program), nameof(Bar)));
 IL.Emit.Constrained<C>();
 IL.Emit.Callvirt(new MethodRef(typeof(C), nameof(arg.Baz)));
 }

 private static int Bar(ref C o)
 {
 o = new C("B");
 return 0;
 }
}

public record class C(string Name)
{
 public void Baz(int arg)
 {
 Console.WriteLine(Name);
 }
}

Expected: B
Actual: A

Seen in #73606 (comment)

Author:	jakobbotsch
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-