[Fuzzlyn] Incorrect T1 behavior around division

[tannergooding]

// Generated by Fuzzlyn v3.1 on 2025-05-29 20:01:16
// Run on X64 Windows
// Seed: 14412340127944514498-vectort,vector128,vector256,x86aes,x86avx,x86avx2,x86avx512bw,x86avx512bwvl,x86avx512cd,x86avx512cdvl,x86avx512dq,x86avx512dqvl,x86avx512f,x86avx512fvl,x86avx512fx64,x86bmi1,x86bmi1x64,x86bmi2,x86bmi2x64,x86fma,x86lzcnt,x86lzcntx64,x86pclmulqdq,x86popcnt,x86popcntx64,x86sse,x86ssex64,x86sse2,x86sse2x64,x86sse3,x86sse41,x86sse41x64,x86sse42,x86sse42x64,x86ssse3,x86x86base
// Reduced from 53.8 KiB to 0.7 KiB in 00:02:59
// Debug: Prints 1 line(s)
// Release: Prints 0 line(s)
using System;
using System.Numerics;
using System.Runtime.Intrinsics;
using System.Runtime.Intrinsics.X86;

public class C0
{
    public ushort F0;
}

public struct S0
{
    public Vector256<int> F0;
}

public class C1
{
    public C0 F0;
    public C1(C0 f0)
    {
        F0 = f0;
    }
}

public class Program
{
    public static void Main()
    {
        var vr1 = new C1(new C0());
        M3(vr1);
    }

    public static void M3(C1 argThis)
    {
        if (0 >= (Bmi2.X64.ZeroHighBits(0, 0) / ((0UL & argThis.F0.F0) | 1)))
        {
            S0[] var1 = new S0[]
            {
                new S0()
            };
            System.Console.WriteLine(var1[0].F0);
        }
    }
}

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[EgorBo]

Doesn't look to be Bmi2 specific, reproduces on:

public static void Main()
{
    ushort y = 0;
    Test(0, ref y);
}

[MethodImpl(MethodImplOptions.NoInlining)]
public static void Test(ulong x, ref ushort y)
{
    if (0 >= x / ((0UL & y) | 1))
        Console.WriteLine("always taken");
}