Process.Linux/OSX: avoid loading full ProcessInfo for ProcessName and ToString.

[tmds]

This speeds up ProcessName/ToString.

It also enables trimming out ProcessInfo support when no APIs that require ProcessInfo are used.

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[jkotas]

Do you have any AOT binary size numbers for how much this saves (e.g. for an all that does just Process.Start("echo").WaitForExit();)

[tmds]

This speeds up ProcessName/ToString.

using System.Diagnostics;

var process = Process.GetCurrentProcess();
var sw = Stopwatch.StartNew();
long iterations = 0;

while (sw.ElapsedMilliseconds < 5000)
{
    _ = process.ProcessName;
    process.Refresh();
    iterations++;
}

sw.Stop();

Console.WriteLine($"Iterations: {iterations}");
Console.WriteLine($"Elapsed: {sw.Elapsed}");
Console.WriteLine($"Per call: {sw.Elapsed.TotalNanoseconds / iterations:F1} ns");

Results on Linux:

.NET 10:
Iterations: 103812
Elapsed: 00:00:05.0000314
Per call: 48164.3 ns

.NET 11:
Iterations: 760767
Elapsed: 00:00:05.0000080
Per call: 6572.3 ns

That is about a 7x speedup.

It also enables trimming out ProcessInfo support when no APIs that require ProcessInfo are used.

On Linux, it trims out about 4.5KB by eliminating the ToString dependency on ProcessInfo. A minor improvement.

[tmds]

Do you have any AOT binary size numbers for how much this saves (e.g. for an all that does just Process.Start("echo").WaitForExit();)

I'll do an exact measurement.

The speed-up turned out to be the actual improvement.
And with that, moving HaveProcessInfo from EnsureState to a separate method made it trimmable too.

[tmds]

Process.Start("echo").WaitForExit(); is 8.2KB smaller.

$ stat -c %s /tmp/nativeaot-out1/nativeaot-test /tmp/nativeaot-out2/nativeaot-test
2163504
2171776