Fuzzlyn: Assertion failed '!m_compiler->lvaInSsa(tree->GetLclNum())' during 'Assertion prop'

[amanasifkhalid]

Hitting on multiple platforms. Example on win-x64:

// Generated by Fuzzlyn v2.4 on 2024-11-17 15:25:04
// Run on X64 Windows
// Seed: 8082722256341804456-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 137.3 KiB to 1.0 KiB in 00:02:31
// Hits JIT assert in Release:
// Assertion failed '!m_compiler->lvaInSsa(tree->GetLclNum())' in 'Program:Main(Fuzzlyn.ExecutionServer.IRuntime)' during 'Assertion prop' (IL size 73; hash 0xade6b36b; FullOpts)
// 
//     File: D:\a\_work\1\s\src\coreclr\jit\optimizer.cpp Line: 3511
// 
using System;
using System.Numerics;
using System.Runtime.Intrinsics;
using System.Runtime.Intrinsics.X86;

public class C0
{
    public sbyte F1;
}

public class C1
{
    public C0 F5;
}

public class Program
{
    public static IRuntime s_rt;
    public static C1 s_1;
    public static C0 s_2;
    public static void Main()
    {
        double vr4 = default(double);
        byte vr5 = 0;
        ushort vr6 = 0;
        if (0 >= vr5)
        {
            s_rt.WriteLine(System.BitConverter.DoubleToUInt64Bits(vr4));
        }
        else
        {
            var vr7 = s_1.F5.F1 % vr6;
            try
            {
                M1();
            }
            finally
            {
                s_2 = s_2;
            }
        }
    }

    public static float M1()
    {
        return default(float);
    }
}

public interface IRuntime
{
    void WriteLine<T>(T value);
}

public class Runtime : IRuntime
{
    public void WriteLine<T>(T value) => System.Console.WriteLine(value);
}

cc @dotnet/jit-contrib

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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
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[jakobbotsch]

Andy pointed me at this one as well but haven't had time to dig in yet... It's likely introduced by my recent SSA changes. I'll take a look.

[jakobbotsch]

The problem here is that we have a CSE use in an unreachable block. Since it's unreachable there is no reaching def so it does not get any SSA number, but optRecordSsaUses is unhappy about that.