[Fuzzlyn] Arm64 failure for negation, cast, bitwise-and

[tannergooding]

1 reduced examples are available

// Generated by Fuzzlyn v1.5 on 2023-04-12 13:58:51
// Run on Arm64 MacOS
// Seed: 15653303803842509097
// Reduced from 14.3 KiB to 0.3 KiB in 00:00:10
// Debug: Outputs 255
// Release: Outputs -1
public class Program
{
    public static short s_2;
    public static void Main()
    {
        sbyte vr5 = (sbyte)M8(1);
    }

    public static uint M8(byte arg0)
    {
        s_2 = 1;
        arg0 = (byte)(-s_2);
        var vr1 = arg0 & arg0;
        System.Console.WriteLine(vr1);
        return 0;
    }
}

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Issue Details

---

1 reduced examples are available

// Generated by Fuzzlyn v1.5 on 2023-04-12 13:58:51
// Run on Arm64 MacOS
// Seed: 15653303803842509097
// Reduced from 14.3 KiB to 0.3 KiB in 00:00:10
// Debug: Outputs 255
// Release: Outputs -1
public class Program
{
    public static short s_2;
    public static void Main()
    {
        sbyte vr5 = (sbyte)M8(1);
    }

    public static uint M8(byte arg0)
    {
        s_2 = 1;
        arg0 = (byte)(-s_2);
        var vr1 = arg0 & arg0;
        System.Console.WriteLine(vr1);
        return 0;
    }
}

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

[TIHan]

Reproduces on Windows ARM64 as well. Will look into it.

[TIHan]

Still looking into the issue. Reproduces even with disabling these optimizations individually and in combination:

• [JIT] X64/ARM64 - CAST removals for small types on ADD, SUB, MUL, AND, OR, XOR, NOT, NEG #77874
• [JIT] X64/ARM64 - Fold 'x & 255' and 'x & 65535' to a cast #79630
• [JIT] Always transform AND(X, CNS(-1)) to X #82276

Does not reproduce on XARCH.

[TIHan]

This reproduces in release/7.0 branch too.

[TIHan]

Disabling the optimization, fgOptimizeCastOnAssignment, fixes the issue though I don't think it's the cause. I think we are not handling NormalizeOnLoad variables correctly on ARM64.