JIT: Assertion failed '!tree->IsUnusedValue() || (dstCount != 0)' during 'Linear scan register alloc'

[jakobbotsch]

// Generated by Fuzzlyn v1.5 on 2023-01-29 16:01:38
// Run on X64 Windows
// Seed: 1558527855815242520
// Reduced from 309.9 KiB to 0.2 KiB in 00:06:49
// Hits JIT assert in Debug:
// Assertion failed '!tree->IsUnusedValue() || (dstCount != 0)' in 'Program:Main(Fuzzlyn.ExecutionServer.IRuntime)' during 'Linear scan register alloc' (IL size 19; hash 0xade6b36b; MinOpts)
// 
//     File: D:\a\_work\1\s\src\coreclr\jit\lsraxarch.cpp Line: 685
// 
public class Program
{
    public static byte[] s_130;
    public static void Main()
    {
        ulong vr5 = default(ulong);
        byte vr4 = (byte)(((byte)vr5 & 0) * s_130[0]);
    }
}

Bisected to 08f13dd, cc @JulieLeeMSFT

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Issue Details

---

// Generated by Fuzzlyn v1.5 on 2023-01-29 16:01:38
// Run on X64 Windows
// Seed: 1558527855815242520
// Reduced from 309.9 KiB to 0.2 KiB in 00:06:49
// Hits JIT assert in Debug:
// Assertion failed '!tree->IsUnusedValue() || (dstCount != 0)' in 'Program:Main(Fuzzlyn.ExecutionServer.IRuntime)' during 'Linear scan register alloc' (IL size 19; hash 0xade6b36b; MinOpts)
// 
//     File: D:\a\_work\1\s\src\coreclr\jit\lsraxarch.cpp Line: 685
// 
public class Program
{
    public static byte[] s_130;
    public static void Main()
    {
        ulong vr5 = default(ulong);
        byte vr4 = (byte)(((byte)vr5 & 0) * s_130[0]);
    }
}

Bisected to 08f13dd, cc @JulieLeeMSFT

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

[kunalspathak]

Seems to be reproing on other platforms as well in Antigen https://dev.azure.com/dnceng-public/public/_build/results?buildId=151999&view=ms.vss-build-web.run-extensions-tab

[kunalspathak]

Introduced by #77078

[kunalspathak]

Introduced by #77078

Ah, just noticed that @jakobbotsch already bisected it :) Working on the fix.