AllocationTick event is missing on NativeAOT

[noahfalk]

Description

For CLR and CoreCLR, .NET supports AllocationTick events. CoreCLR is currently on version 4 of the event though the docs only mention version 3 right now.

NativeAOT has the GC code ifdefed to only trigger the v1 version of AllocationTick:

runtime/src/coreclr/gc/gcee.cpp

Lines 311 to 313 in 204f0e1

	#ifdef FEATURE_NATIVEAOT
	FIRE_EVENT(GCAllocationTick_V1, (uint32_t)allocation_amount, (uint32_t)gen_to_oh (gen_number));
	#else

However it also has an empty method body in the runtime code which receives this event so nothing is logged:

runtime/src/coreclr/nativeaot/Runtime/gctoclreventsink.cpp

Lines 161 to 164 in 204f0e1

	void GCToCLREventSink::FireGCAllocationTick_V1(uint32_t allocationAmount,
	uint32_t allocationKind)
	{
	}

We discovered this while investigating for the new AllocationSampled event that is being added #100356

I'm mostly just filing the issue to document the absence of this event given other docs didn't appear specific about which events are supported and which are not. The event would generally be used by allocation profilers. In the future profilers may switch over to the new AllocationSampled event so I don't know that its particularly important to support AllocationTick, but its likely current allocation profilers don't work because of its absence. 

Reproduction Steps

Use an ETW or EventPipe profiler to listen to GC verbose events, run any NativeAOT app that does a bunch of allocation.

Expected behavior

AllocationTick events would be emitted

Actual behavior

AllocationTick events are not emitted

Regression?

Don't know, but probably not.

Known Workarounds

In the future, use the AllocationSampled event instead. For now you could try not compiling the app as NativeAOT, profile it with a tool that supports CoreCLR, and hope that it has a similar allocation pattern.

Configuration

No response

Other information

No response

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[noahfalk]

fyi @brianrob