Bug 21645 - Slow invocation of generic method on value type
Summary: Slow invocation of generic method on value type
Status: RESOLVED FIXED
Alias: None
Product: Runtime
Classification: Mono
Component: JIT ()
Version: unspecified
Hardware: PC Mac OS
: --- normal
Target Milestone: ---
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2014-07-28 15:01 UTC by Marek Safar
Modified: 2014-07-29 00:32 UTC (History)
3 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:

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Related Links:
Status:
RESOLVED FIXED

Description Marek Safar 2014-07-28 15:01:58 UTC
using System;
using System.Xml;
using System.Globalization;
using System.Threading;
using System.Diagnostics;

interface I
{
	int TestMe ();
}

struct C : I
{
	public int TestMe ()
	{
		return 4;
	}
}

static class X
{
    static int TestGeneric<T> (T t) where T : struct, I
    {
    	return t.TestMe ();
    }

	public static void Main ()
	{
		var sw = new Stopwatch ();
		sw.Start ();

		var c = new C ();
		const int iter = 1000000000;
		int res = 0;
		for (int i = 0; i < iter; ++i) {
			res = TestGeneric (c);
		}

		sw.Stop ();
		Console.WriteLine (sw.Elapsed);
		Console.WriteLine (res);

		return;
	}

}

Mono: 04.5923078
.NET: 00.1720799

That's about 30x slower
Comment 1 Rodrigo Kumpera 2014-07-28 23:07:55 UTC
The problem here is not with generic invocation as all calls in the loop are inlined but that our AA pass is not working as it should on this case.
Comment 2 Rodrigo Kumpera 2014-07-29 00:32:21 UTC
Fixed on master.