[NativeAOT] Move RequiresAlign8 flag from RareFlags into ExtendedFlags

[filipnavara]

Implementation of idea from https://github.com/dotnet/runtime/pull/105931/files#r1704319780.

The benchmark code and results are below. I tested it on Raspberry Pi. The tests were run in succession, CPU temperature was around 48 degrees, so no thermal throttling should be involved.

Predictably, the performance improves for `RequiresAlign8` cases where we don't need to decode the optional fields block. There's about 5% perf hit for non-align8 array allocations and 2% perf hit for non-align8 value type allocations. Some perf hit for arrays was expected, the other code path needs more investigation though as no hit is expected there.

Updated benchmark results here: #106010 (comment)

This would make it easier to set the RequiresAlign8 flag for truncated method tables used in GCStaticEETypeNode.

Benchmark code:

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.Runtime;
using System.Runtime.CompilerServices;

public unsafe class Program
{
    [RuntimeImport("RhNewObject")]
    [MethodImpl(MethodImplOptions.InternalCall)]
    private static extern object RhNewObject(void* pMT);
    [RuntimeImport("RhNewArray")]
    [MethodImpl(MethodImplOptions.InternalCall)]
    private static extern object RhNewArray(void* pMT, int length);

    public static void Main()
    {
        var stopWatch = new System.Diagnostics.Stopwatch();

        for (int j = 0; j < 10; j++)
        {
            stopWatch.Restart();
            for (int i = 0; i < 1000000; i++)
                _ = RhNewArray((void*)typeof(int[]).TypeHandle.Value, 2);
            stopWatch.Stop();
            Console.WriteLine("NewIntArray: " + stopWatch.Elapsed);
        }

        for (int j = 0; j < 10; j++)
        {
            stopWatch.Restart();
            for (int i = 0; i < 1000000; i++)
                _ = RhNewArray((void*)typeof(double[]).TypeHandle.Value, 2);
            stopWatch.Stop();
            Console.WriteLine("NewDoubleArray: " + stopWatch.Elapsed);
        }

        for (int j = 0; j < 10; j++)
        {
            stopWatch.Restart();
            for (int i = 0; i < 1000000; i++)
                _ = RhNewObject((void*)typeof(ValueTuple<int, int>).TypeHandle.Value);
            stopWatch.Stop();
            Console.WriteLine("NewIntTuple: " + stopWatch.Elapsed);
        }

        for (int j = 0; j < 10; j++)
        {
            stopWatch.Restart();
            for (int i = 0; i < 1000000; i++)
                _ = RhNewObject((void*)typeof(ValueTuple<double, double>).TypeHandle.Value);
            stopWatch.Stop();
            Console.WriteLine("NewDoubleTuple: " + stopWatch.Elapsed);
        }
    }
}

namespace System.Runtime
{
    public class RuntimeImportAttribute : Attribute
    {
        public string DllName { get; }
        public string EntryPoint { get; }
        public RuntimeImportAttribute(string entry) => EntryPoint = entry;
    }
}

Benchmark results (on Raspberry Pi):

Main

PR

NewIntArray: 00:00:00.0255011 NewIntArray: 00:00:00.0254985 NewIntArray: 00:00:00.0199294 NewIntArray: 00:00:00.0157785 NewIntArray: 00:00:00.0158397 NewIntArray: 00:00:00.0157611 NewIntArray: 00:00:00.0158823 NewIntArray: 00:00:00.0157390 NewIntArray: 00:00:00.0157586 NewIntArray: 00:00:00.0158148 NewDoubleArray: 00:00:00.0634320 NewDoubleArray: 00:00:00.0634249 NewDoubleArray: 00:00:00.0634018 NewDoubleArray: 00:00:00.0634123 NewDoubleArray: 00:00:00.0633429 NewDoubleArray: 00:00:00.0633701 NewDoubleArray: 00:00:00.0633932 NewDoubleArray: 00:00:00.0633275 NewDoubleArray: 00:00:00.0633318 NewDoubleArray: 00:00:00.0633482 NewIntTuple: 00:00:00.0142524 NewIntTuple: 00:00:00.0142566 NewIntTuple: 00:00:00.0142554 NewIntTuple: 00:00:00.0142424 NewIntTuple: 00:00:00.0142489 NewIntTuple: 00:00:00.0142521 NewIntTuple: 00:00:00.0142627 NewIntTuple: 00:00:00.0142432 NewIntTuple: 00:00:00.0142473 NewIntTuple: 00:00:00.0142491 NewDoubleTuple: 00:00:00.0269727 NewDoubleTuple: 00:00:00.0270101 NewDoubleTuple: 00:00:00.0269876 NewDoubleTuple: 00:00:00.0269796 NewDoubleTuple: 00:00:00.0269837 NewDoubleTuple: 00:00:00.0269709 NewDoubleTuple: 00:00:00.0270441 NewDoubleTuple: 00:00:00.0269772 NewDoubleTuple: 00:00:00.0269737 NewDoubleTuple: 00:00:00.0269802

NewIntArray: 00:00:00.0266514 NewIntArray: 00:00:00.0267529 NewIntArray: 00:00:00.0264482 NewIntArray: 00:00:00.0173164 NewIntArray: 00:00:00.0164856 NewIntArray: 00:00:00.0164668 NewIntArray: 00:00:00.0165303 NewIntArray: 00:00:00.0164860 NewIntArray: 00:00:00.0164870 NewIntArray: 00:00:00.0164756 NewDoubleArray: 00:00:00.0513089 NewDoubleArray: 00:00:00.0513532 NewDoubleArray: 00:00:00.0513423 NewDoubleArray: 00:00:00.0513160 NewDoubleArray: 00:00:00.0513266 NewDoubleArray: 00:00:00.0512910 NewDoubleArray: 00:00:00.0512942 NewDoubleArray: 00:00:00.0513139 NewDoubleArray: 00:00:00.0512965 NewDoubleArray: 00:00:00.0512951 NewIntTuple: 00:00:00.0144171 NewIntTuple: 00:00:00.0144348 NewIntTuple: 00:00:00.0144299 NewIntTuple: 00:00:00.0143846 NewIntTuple: 00:00:00.0144250 NewIntTuple: 00:00:00.0143741 NewIntTuple: 00:00:00.0143745 NewIntTuple: 00:00:00.0144070 NewIntTuple: 00:00:00.0144361 NewIntTuple: 00:00:00.0144255 NewDoubleTuple: 00:00:00.0162535 NewDoubleTuple: 00:00:00.0162460 NewDoubleTuple: 00:00:00.0162538 NewDoubleTuple: 00:00:00.0162349 NewDoubleTuple: 00:00:00.0162483 NewDoubleTuple: 00:00:00.0162368 NewDoubleTuple: 00:00:00.0162206 NewDoubleTuple: 00:00:00.0162730 NewDoubleTuple: 00:00:00.0163367 NewDoubleTuple: 00:00:00.0162350

[dotnet-policy-service]

Tagging subscribers to this area: @agocke, @MichalStrehovsky, @jkotas
See info in area-owners.md if you want to be subscribed.

[filipnavara]

Closing for now, the benchmark is flawed.

[filipnavara]

Updated the OP with a fixed benchmark and more meaningful numbers. I'll will tinker a bit more with it.

[filipnavara]

I rewrote the RequiresAlign8 getter by exploiting a bit trick used in HasComponentSize. Now it beats the old version in the benchmarks in all cases.

Benchmark results (on Raspberry Pi):

Main

PR

NewIntArray: 00:00:00.0253658 NewIntArray: 00:00:00.0255230 NewIntArray: 00:00:00.0251697 NewIntArray: 00:00:00.0221124 NewIntArray: 00:00:00.0156506 NewIntArray: 00:00:00.0157653 NewIntArray: 00:00:00.0157124 NewIntArray: 00:00:00.0157753 NewIntArray: 00:00:00.0157293 NewIntArray: 00:00:00.0156424 NewDoubleArray: 00:00:00.0631696 NewDoubleArray: 00:00:00.0631607 NewDoubleArray: 00:00:00.0631175 NewDoubleArray: 00:00:00.0631376 NewDoubleArray: 00:00:00.0632945 NewDoubleArray: 00:00:00.0631229 NewDoubleArray: 00:00:00.0631233 NewDoubleArray: 00:00:00.0630915 NewDoubleArray: 00:00:00.0631253 NewDoubleArray: 00:00:00.0631230 NewIntTuple: 00:00:00.0142051 NewIntTuple: 00:00:00.0142171 NewIntTuple: 00:00:00.0142024 NewIntTuple: 00:00:00.0141806 NewIntTuple: 00:00:00.0142125 NewIntTuple: 00:00:00.0142099 NewIntTuple: 00:00:00.0141944 NewIntTuple: 00:00:00.0141997 NewIntTuple: 00:00:00.0142020 NewIntTuple: 00:00:00.0141909 NewDoubleTuple: 00:00:00.0269583 NewDoubleTuple: 00:00:00.0269372 NewDoubleTuple: 00:00:00.0269473 NewDoubleTuple: 00:00:00.0269310 NewDoubleTuple: 00:00:00.0269361 NewDoubleTuple: 00:00:00.0269333 NewDoubleTuple: 00:00:00.0269077 NewDoubleTuple: 00:00:00.0269356 NewDoubleTuple: 00:00:00.0269354 NewDoubleTuple: 00:00:00.0269354

NewIntArray: 00:00:00.0230733 NewIntArray: 00:00:00.0237831 NewIntArray: 00:00:00.0234446 NewIntArray: 00:00:00.0232283 NewIntArray: 00:00:00.0143300 NewIntArray: 00:00:00.0143772 NewIntArray: 00:00:00.0143603 NewIntArray: 00:00:00.0143911 NewIntArray: 00:00:00.0143334 NewIntArray: 00:00:00.0144492 NewDoubleArray: 00:00:00.0508229 NewDoubleArray: 00:00:00.0509037 NewDoubleArray: 00:00:00.0510827 NewDoubleArray: 00:00:00.0505703 NewDoubleArray: 00:00:00.0506560 NewDoubleArray: 00:00:00.0505697 NewDoubleArray: 00:00:00.0507030 NewDoubleArray: 00:00:00.0506166 NewDoubleArray: 00:00:00.0505482 NewDoubleArray: 00:00:00.0505669 NewIntTuple: 00:00:00.0138182 NewIntTuple: 00:00:00.0138272 NewIntTuple: 00:00:00.0137903 NewIntTuple: 00:00:00.0138285 NewIntTuple: 00:00:00.0138366 NewIntTuple: 00:00:00.0138224 NewIntTuple: 00:00:00.0137791 NewIntTuple: 00:00:00.0138458 NewIntTuple: 00:00:00.0138181 NewIntTuple: 00:00:00.0138305 NewDoubleTuple: 00:00:00.0154690 NewDoubleTuple: 00:00:00.0155391 NewDoubleTuple: 00:00:00.0154707 NewDoubleTuple: 00:00:00.0155383 NewDoubleTuple: 00:00:00.0154718 NewDoubleTuple: 00:00:00.0155317 NewDoubleTuple: 00:00:00.0154563 NewDoubleTuple: 00:00:00.0155298 NewDoubleTuple: 00:00:00.0154692 NewDoubleTuple: 00:00:00.0155386

[jkotas]

How do we store RequiresAlign8 for arrays of value types with this change? If I am reading the code correctly, RequiresAlign8 is always going to be false for arrays with this change.

[filipnavara]

How do we store RequiresAlign8 for arrays of value types with this change?

We don’t. We just check the element type of the array for IsValueType && RequiresAlign8. The array allocation path is separate so the cost of the check is moved there. I meant to add Debug.Assert(!IsArray) into the getter but forgot about it.

[jkotas]

If the getter is not supposed to be called on arrays, we can omit the HasComponentSizeFlag tricks from it and just test the single bit.

[filipnavara]

The HasComponentSizeFlag check is still needed for string.

[jkotas]

I would expect that string allocations to be always special cased. Where is the RequiresAlign8 checked for string allocations?

[filipnavara]

I would expect that string allocations to be always special cased. Where is the RequiresAlign8 checked for string allocations?

Presumably you are right. I checked all the code paths and couldn’t find one that would be hit with string. Moreover, there’s already an assert in RhNewObject to disallow strings. I’ll simplify the check.

[filipnavara]

This should definitely run through the NativeAOT outerloop tests if the PR looks reasonable in other aspects.

[jkotas]

/azp run runtime-nativeaot-outerloop

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[jkotas]

LGTM!

[jkotas]

A lot of tests on linux-arm crashing with stackoverflow:

ld_linux_armhf_so!_tls_get_addr+0x5
baseservices!S_P_CoreLib_System_Threading_Lock::EnterAndGetCurrentThreadId+0x16 [/_/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs @ 83] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner_Cctor::GetCctor+0x2e [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 279] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner::EnsureClassConstructorRun+0x2a [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 66] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner::CheckStaticClassConstructionReturnGCStaticBase+0x10 [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 36] 
baseservices!S_P_CoreLib_Internal_Runtime_ThreadStatics::AllocateThreadStaticStorageForType+0x7e [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/ThreadStatics.cs @ 140] 
baseservices!S_P_CoreLib_Internal_Runtime_ThreadStatics::GetUninlinedThreadStaticBaseForTypeSlow+0x146 [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/ThreadStatics.cs @ 110] 
baseservices!S_P_CoreLib_System_Threading_Lock::EnterAndGetCurrentThreadId+0x16 [/_/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs @ 83] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner_Cctor::GetCctor+0x2e [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 279] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner::EnsureClassConstructorRun+0x2a [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 66] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner::CheckStaticClassConstructionReturnGCStaticBase+0x10 [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 36] 
baseservices!S_P_CoreLib_Internal_Runtime_ThreadStatics::AllocateThreadStaticStorageForType+0x7e [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/ThreadStatics.cs @ 140] 
baseservices!S_P_CoreLib_Internal_Runtime_ThreadStatics::GetUninlinedThreadStaticBaseForTypeSlow+0x146 [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/ThreadStatics.cs @ 110] 
baseservices!S_P_CoreLib_System_Threading_Lock::EnterAndGetCurrentThreadId+0x16 [/_/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs @ 83] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner_Cctor::GetCctor+0x2e [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 279] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner::EnsureClassConstructorRun+0x2a [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 66] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner::CheckStaticClassConstructionReturnGCStaticBase+0x10 [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 36] 
baseservices!S_P_CoreLib_Internal_Runtime_ThreadStatics::AllocateThreadStaticStorageForType+0x7e [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/ThreadStatics.cs @ 140] 
baseservices!S_P_CoreLib_Internal_Runtime_ThreadStatics::GetUninlinedThreadStaticBaseForTypeSlow+0x146 [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/ThreadStatics.cs @ 110] 
baseservices!S_P_CoreLib_System_Threading_Lock::EnterAndGetCurrentThreadId+0x16 [/_/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs @ 83] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner_Cctor::GetCctor+0x2e [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 279] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner::EnsureClassConstructorRun+0x2a [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 66] 
baseservices!S_P_CoreLib_System_Runtime_CompilerServices_ClassConstructorRunner::CheckStaticClassConstructionReturnGCStaticBase+0x10 [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/ClassConstructorRunner.cs @ 36] 
baseservices!S_P_CoreLib_Internal_Runtime_ThreadStatics::AllocateThreadStaticStorageForType+0x7e [/_/src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/ThreadStatics.cs @ 140] 
...

[filipnavara]

A lot of tests on linux-arm crashing with stackoverflow:

It was a very stupid mistake in the last change.

[MichalStrehovsky]

/azp run runtime-nativeaot-outerloop

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Azure Pipelines successfully started running 1 pipeline(s).