Is there a way to force tier 1 compilation of a method?

[ladeak]

I have a method in .NET8 (windows, not R2R) that is compiled as (using DOTNET_JitDisasm):

; Assembly listing for method MyType:SomeMethod[System.__Canon](System.Collections.Generic.Dictionary`2[System.String,System.String],System.String):System.__Canon (Tier0)
; Emitting BLENDED_CODE for X64 with AVX - Windows
; Tier0 code
; rbp based frame
; partially interruptible

Regardless, if I invoke it thousands of times, I do not see a Tier 1 compilation created for it (and this is the only method I have in my solution. Is there a way to gain understanding why there is no Tier 1 compilation happening?

Applying the AggressiveOptimization attribute still produces Tier-0 optimized flag.

Is there a way to force tier 1 compilation of a method?

I wonder because I wonder what happens when I use this method in a real production app. Is it not ever going to have a tier 1 code?

[gfoidl]

if I invoke it thousands of times, I do not see a Tier 1 compilation created for it

Tiered compilation kicks in when the method is called often enough and after a period of time where no JIT-compilations happens (to settle a starting phase, etc.).

So when you just call the method at app entry the thousands time the second criteria (time) isn't fulfilled.
Thus try it that way:

• call your method say 50 times
• Thread.Sleep(250) to let the statup timeout pass and a bit of time to let the JIT produce Tier-1 code
• call your method again -- now Tier-1 code should be logged via disams

---

Does you code contain loops?

[ladeak]

That is exactly what I have. I am looking for ByTypeCastMediaTypeHeaderValue:

var myObj = ...
int length = 0;
for (int i = 0; i < 16_000; i++)
    length += myObj.ByTypeCastMediaTypeHeaderValue().MediaType.Length;

await Task.Delay(1000);

for (int i = 0; i < 300; i++)
    length += myObj.ByTypeCastMediaTypeHeaderValue().MediaType.Length;

Console.WriteLine(length);

[KeterSCP]

Can you try with?

for (int i = 0; i < 100; i++)
{
    length += myObj.ByTypeCastMediaTypeHeaderValue().MediaType.Length;
    Thread.Sleep(10);
}

[ladeak]

Yes, that does the trick:

; Assembly listing for method MyType:SomeMethod[System.__Canon](System.Collections.Generic.Dictionary`2[System.String,System.String],System.String):System.__Canon (Tier1)
; Emitting BLENDED_CODE for X64 with AVX - Windows
; Tier1 code
; optimized code
; optimized using Dynamic PGO

[MichalPetryka]

Applying the AggressiveOptimization attribute still produces Tier-0 optimized flag.

AggressiveOptimization won't emit Tier1 codegen (it'll be slightly worse) but it won't ever emit Tier0, you must've done something wrong to see that.

[ladeak]

I recall seeing tier 0 optimized, but might remembering it incorrectly.