FltToInt: OverflowException in Debug and no exception in Release

[EgorBo]

I noticed that we assign the same VN for "checked" and "unchecked" conversions from double to integer here, so I came up with the following repro that throws OverflowException in Debug (as expected) and prints "done" in Release:

using System;

public class Program
{
    static double fld = double.MaxValue;

    static void Main()
    {
        double x = fld;
        try { Console.WriteLine(checked((ulong)x)); } catch { }

        if ((ulong)x == checked((ulong)x)) // should throw here
            Console.WriteLine("done"); // not expected to be invoked
    }
}

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Issue Details

---

I noticed that we assign the same VN for "checked" and "unchecked" conversions from double to integer here, so I came up with the following repro that throws OverflowException in Debug (as expected) and prints "done" in Release:

using System;

public class Program
{
    static double fld = double.MaxValue;

    static void Main()
    {
        double x = fld;
        try { Console.WriteLine(checked((ulong)x)); } catch { }

        if ((ulong)x == checked((ulong)x)) // should throw here
            Console.WriteLine("done"); // not expected to be invoked
    }
}

Author:	EgorBo
Assignees:	EgorBo
Labels:	area-CodeGen-coreclr, untriaged
Milestone:	6.0.0

[SingleAccretion]

Quite surprising this wasn't caught while I was adding VN tests for all these casts.

.NET 6 fix would be to add the overflow exception somewhere here.

.NET 7 fix is to delete all the VNFuncs for helpers (they're not needed anymore) and route all the codepaths through VNForCast, which should also add the exception set.