1 XOR 1 computes to 1 in release mode

[bradmarder]

Description

@jakobbotsch

1 ^ 1 should compute to 0 in release mode.

Reproduction Steps

// Generated by Fuzzlyn v1.5 on 2023-01-16 17:01:38
// Run on X64 Windows
// Seed: 10178493004625664135
// Reduced from 625.1 KiB to 1.5 KiB in 00:03:14
// Debug: Outputs 0
// Release: Outputs 1
public struct S0
{
	public bool F1;
}

public struct S1
{
	public S0 F2;
}

public class Program
{
	public static ushort s_19;
	public static S1 s_21;
	public static ushort[] s_32;

	public static void Main()
	{
		ulong[] vr0 = new ulong[] { 0 };
		for (int vr1 = 0; vr1 < 2; vr1++)
		{
			vr0[0] = 1;
			if (s_21.F2.F1)
			{
				s_32[0] = s_19;
			}

			vr0[0] ^= vr0[0];
			Console.WriteLine(vr1);
		}
		Console.WriteLine(vr0[0]);
	}
}

Expected behavior

1 ^ 1 should compute to 0.

Actual behavior

1 ^ 1 computes to 1.

Regression?

No, reproduces in net6.

Known Workarounds

No response

Configuration

No response

Other information

No response

[ghost]

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Issue Details

---

Description

@jakobbotsch

1 ^ 1 should compute to 0 in release mode.

Reproduction Steps

// Generated by Fuzzlyn v1.5 on 2023-01-16 17:01:38
// Run on X64 Windows
// Seed: 10178493004625664135
// Reduced from 625.1 KiB to 1.5 KiB in 00:03:14
// Debug: Outputs 0
// Release: Outputs 1
public struct S0
{
	public bool F1;
}

public struct S1
{
	public S0 F2;
}

public class Program
{
	public static ushort s_19;
	public static S1 s_21;
	public static ushort[] s_32;

	public static void Main()
	{
		ulong[] vr0 = new ulong[] { 0 };
		for (int vr1 = 0; vr1 < 2; vr1++)
		{
			vr0[0] = 1;
			if (s_21.F2.F1)
			{
				s_32[0] = s_19;
			}

			vr0[0] ^= vr0[0];
			Console.WriteLine(vr1);
		}
		Console.WriteLine(vr0[0]);
	}
}

Expected behavior

1 ^ 1 should compute to 0.

Actual behavior

1 ^ 1 computes to 1.

Regression?

No, reproduces in net6.

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	bradmarder
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[EgorBo]

From a quick glance it's Loop Hoisting hoisted vr0[0]

[jakobbotsch]

This is probably a duplicate of #75442.

[jakobbotsch]

Closing as a dup of #75442