App sizes are currently significantly bigger with .NET 6 with a very simple hello world app.

Test case

Checkout xamarin-macios
Execute:

cd tests/dotnet
make compare

This will build a very simple hello world app for both .NET 6 and the old-style Xamarin.iOS and generate a report in markdown format. This can be pasted into the issue (e.g. for each preview) so the progress can be tracked.

Known Issues

[x] The (dynamic) registrar isn't removed when enabling all the optimizations
- The dynamic registrar requires a larger subset of System.Reflection API (see below)
[x] The .NET 6 version does not strip the native executable.
[x] The mono-cil-strip tool is not run on the final assemblies (it's not available without the mono SDK installed)
- All assemblies still have their IL even when it's not required (FullAOT by default for device builds)
- Tracked, among other tools, in https://github.com/dotnet/runtime/issues/35852 @marek-safar recently mentioned it was being looked at for Blazor (there might be another issue I missed)

Historical

App sizes

Xamarin.iOS

du -hs size-comparison/MySingleView/oldnet/bin/iPhone/Release/MySingleView.app 4.4M size-comparison/MySingleView/oldnet/bin/iPhone/Release/MySingleView.app

.NET 6

du -hs size-comparison/MySingleView/dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/*.app 27M size-comparison/MySingleView/dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/MySingleView.app

Assembly sizes

Xamarin.iOS

ls -lahS size-comparison/MySingleView/oldnet/bin/iPhone/Release/MySingleView.app/.dll size-comparison/MySingleView/oldnet/bin/iPhone/Release/MySingleView.app/.exe -rw-r--r-- 1 rolf wheel 397K Dec 9 19:04 size-comparison/MySingleView/oldnet/bin/iPhone/Release/MySingleView.app/mscorlib.dll -rw-r--r-- 1 rolf wheel 54K Dec 9 19:04 size-comparison/MySingleView/oldnet/bin/iPhone/Release/MySingleView.app/Xamarin.iOS.dll -rw-r--r-- 1 rolf wheel 4.5K Dec 9 19:04 size-comparison/MySingleView/oldnet/bin/iPhone/Release/MySingleView.app/MySingleView.exe -rw-r--r-- 1 rolf wheel 4.5K Dec 9 19:05 size-comparison/MySingleView/oldnet/bin/iPhone/Release/MySingleView.app/System.dll

.NET 6

ls -lahS size-comparison/MySingleView/dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/.app/.dll -rw-r--r-- 1 rolf wheel 1.3M Dec 9 19:05 size-comparison/MySingleView/dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/MySingleView.app/System.Private.CoreLib.dll -rw-r--r-- 1 rolf wheel 161K Dec 9 19:05 size-comparison/MySingleView/dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/MySingleView.app/Xamarin.iOS.dll -rw-r--r-- 1 rolf wheel 17K Dec 9 19:05 size-comparison/MySingleView/dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/MySingleView.app/System.Runtime.dll -rw-r--r-- 1 rolf wheel 16K Dec 9 19:05 size-comparison/MySingleView/dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/MySingleView.app/System.Runtime.Serialization.Formatters.dll -rw-r--r-- 1 rolf wheel 5.0K Dec 9 19:05 size-comparison/MySingleView/dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/MySingleView.app/MySingleView.dll

There are multiple issues here:

[x] ~The .NET 6 version has unnecessary dylibs (because it's linking libraries statically).~ fix
[x] ~The .NET 6 version does not strip the native executable.~
[ ] The .NET 6 version's assemblies are much bigger (the linker doesn't remove as much): 1,5 MB vs 460 KB.

Additionally the .NET 6 version takes twice as long to compile (22s vs 11s on my machine), but that's a different issue (filed as https://github.com/xamarin/xamarin-macios/issues/10251).

Dec 09 '20 18:12 rolfbjarne

Shameless plug but you might want to use https://github.com/spouliot/dotnet-tools/tree/master/app-compare to compare the size of the current/dotnet apps

Dec 09 '20 18:12 spouliot

Additionally the .NET 6 version takes twice as long to compile (22s vs 11s on my machine), but that's a different issue.

Considering most of the device build time comes from the AOT compiler (at least in current form) then a 2x build time increase is not so bad as there's more than 3x more managed code (1,5 MB vs 460 KB) to AOT. IOW we can consider this the "same issue", unless the time increase comes from elsewhere.

Dec 09 '20 18:12 spouliot

It looks like you don't have some of the feature switched enabled, see https://github.com/dotnet/runtime/blob/master/docs/workflow/trimming/feature-switches.md. I'm not saying that's all that needs to be done but it's a good start ;-)

Dec 09 '20 19:12 marek-safar

Application Comparer

A oldnet/bin/iPhone/Release/MySingleView.app
B dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/MySingleView.app

Directories / Files	A	B	diff	%
.//_CodeSignature
.//
embedded.mobileprovision	12,218	12,218	0	0.0%
Info.plist	1,055	1,055	0	0.0%
libmonosgen-2.0.dylib	0	3,177,312	3,177,312	-
libSystem.IO.Compression.Native.dylib	0	827,104	827,104	-
libSystem.Native.dylib	0	123,040	123,040	-
libSystem.Net.Security.Native.dylib	0	72,016	72,016	-
libSystem.Security.Cryptography.Native.Apple.dylib	0	80,656	80,656	-
libxamarin-debug.dylib	0	623,856	623,856	-
libxamarin.dylib	0	425,408	425,408	-
mscorlib.aotdata.arm64	296,872	0	-296,872	-100.0%
mscorlib.dll	406,528	0	-406,528	-100.0%
MySingleView	3,748,192	18,281,760	14,533,568	387.7%
MySingleView.aotdata.arm64	816	1,136	320	39.2%
MySingleView.dll	0	5,120	5,120	-
MySingleView.exe	4,608	0	-4,608	-100.0%
MySingleView.pdb	0	9,720	9,720	-
PkgInfo	8	8	0	0.0%
System.aotdata.arm64	752	0	-752	-100.0%
System.dll	4,608	0	-4,608	-100.0%
System.Private.CoreLib.aotdata.arm64	0	3,082,504	3,082,504	-
System.Private.CoreLib.dll	0	1,391,616	1,391,616	-
System.Runtime.aotdata.arm64	0	504	504	-
System.Runtime.dll	0	17,408	17,408	-
System.Runtime.Serialization.Formatters.aotdata.arm64	0	1,144	1,144	-
System.Runtime.Serialization.Formatters.dll	0	15,872	15,872	-
Xamarin.iOS.aotdata.arm64	35,048	319,112	284,064	810.5%
Xamarin.iOS.dll	55,296	163,840	108,544	196.3%

Statistics

Native subtotal	3,748,192	18,281,760	14,533,568	387.7%
Executable	3,748,192	18,281,760	14,533,568	387.7%
AOT data *.aotdata	0	0	0	-

Managed *.dll/exe	471,040	1,593,856	1,122,816	238.4%

TOTAL	4,571,262	28,640,968	24,069,706	526.5%

Dec 09 '20 20:12 spouliot

other issues

[x] ~debugging symbol files, like MySingleView.pdb, should not be copied to release .app~
[x] ~otool -L MySingleView does not show libicu* nor is there any data files. AFAIK those are required for globalization of net5+ apps (and the existing oldnet app has globalization support)~

update: both issues are fixed with P4

Dec 09 '20 21:12 spouliot

@spouliot could you share the binaries?

Dec 09 '20 21:12 marek-safar

@marek-safar yes but likely not today. My main internet connection is down :( and I'm waiting for a new modem to be delivered. Trying to limit myself to low bandwidth (cellular) tasks.

Dec 09 '20 21:12 spouliot

It looks like you don't have some of the feature switched enabled, see https://github.com/dotnet/runtime/blob/master/docs/workflow/trimming/feature-switches.md. I'm not saying that's all that needs to be done but it's a good start ;-)

https://github.com/xamarin/xamarin-macios/pull/10250 - that shaves off a good chunk.

Dec 10 '20 09:12 rolfbjarne

@marek-safar

@spouliot could you share the binaries?

dotnet.zip oldnet.zip

That's after https://github.com/xamarin/xamarin-macios/pull/10250, so the runtime switches have been toggled for these apps.

Dec 10 '20 09:12 rolfbjarne

Additionally the .NET 6 version takes twice as long to compile (22s vs 11s on my machine), but that's a different issue.

Considering most of the device build time comes from the AOT compiler (at least in current form) then a 2x build time increase is not so bad as there's more than 3x more managed code (1,5 MB vs 460 KB) to AOT. IOW we can consider this the "same issue", unless the time increase comes from elsewhere.

I filed https://github.com/xamarin/xamarin-macios/issues/10251 for this: just executing the .NET 6 linker takes longer than linking + AOT compilation + native compilation used to.

Dec 10 '20 09:12 rolfbjarne

This update was done with today's dotnet 6.0.100-preview.2.21158.2 build and xamarin-macios main 91ce22c57cadd3519ac4433e8d73cbe4be5be7e5. Not quite the final, to be released, P2 bits but close.

Most of the previous comments (e.g. extra files, no ICU in numbers) still applies.

Noticeable/visible changes are:

removal of System.Runtime.dll
removal of System.Runtime.Serialization.Formatters.dll
reduction of System.Private.CoreLib.dll

It's a great improvement, over the original numbers, but there's still work to be done compared to the current SDK size.

Application Comparer

A /Users/poupou/git/master/xamarin-macios/tests/dotnet/size-comparison/MySingleView/oldnet/bin/iPhone/Release/MySingleView.app
B /Users/poupou/git/master/xamarin-macios/tests/dotnet/size-comparison/MySingleView/dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/MySingleView.app

Directories / Files	A	B	diff	%
.//_CodeSignature
.//
embedded.mobileprovision	14,271	14,271	0	0.0%
Info.plist	1,058	1,058	0	0.0%
libmonosgen-2.0.dylib	0	3,503,920	3,503,920	-
libSystem.IO.Compression.Native.dylib	0	827,248	827,248	-
libSystem.Native.dylib	0	123,792	123,792	-
libSystem.Net.Security.Native.dylib	0	72,016	72,016	-
libSystem.Security.Cryptography.Native.Apple.dylib	0	80,656	80,656	-
libxamarin-debug.dylib	0	625,472	625,472	-
libxamarin-dotnet-debug.dylib	0	625,600	625,600	-
libxamarin-dotnet.dylib	0	425,984	425,984	-
libxamarin.dylib	0	425,856	425,856	-
mscorlib.aotdata.arm64	296,808	0	-296,808	-100.0%
mscorlib.dll	406,528	0	-406,528	-100.0%
MySingleView	3,748,304	10,213,120	6,464,816	172.5%
MySingleView.aotdata.arm64	816	792	-24	-2.9%
MySingleView.dll	0	4,608	4,608	-
MySingleView.exe	4,608	0	-4,608	-100.0%
MySingleView.pdb	0	10,280	10,280	-
PkgInfo	8	8	0	0.0%
System.aotdata.arm64	752	0	-752	-100.0%
System.dll	4,608	0	-4,608	-100.0%
System.Private.CoreLib.aotdata.arm64	0	623,496	623,496	-
System.Private.CoreLib.dll	0	685,056	685,056	-
Xamarin.iOS.aotdata.arm64	34,856	78,784	43,928	126.0%
Xamarin.iOS.dll	55,296	157,696	102,400	185.2%

Statistics

Native subtotal	3,748,304	10,213,120	6,464,816	172.5%
Executable	3,748,304	10,213,120	6,464,816	172.5%
AOT data *.aotdata	0	0	0	-

Managed *.dll/exe	471,040	847,360	376,320	79.9%

TOTAL	4,573,174	18,507,576	13,934,402	304.7%

Mar 09 '21 18:03 spouliot

@spouliot @rolfbjarne - do we know why Xamarin.iOS.dll is 185% larger in .NET 6?

That could contribute a lot to why .NET 6's CoreLib is bigger than mono's mscorlib. More code in higher level assemblies means the possibility of more code being rooted lower in corelib.

Mar 11 '21 21:03 eerhardt

do we know why Xamarin.iOS.dll is 185% larger in .NET 6?

No, at least not yet. I wanted numbers to go along P2 even if we did not have time to look at the results right away - they will have historical value ;-)

Quick guess some of our optimizations were not yet ported/enabled (last time I checked).

That could contribute a lot to why .NET 6's CoreLib is bigger than mono's mscorlib.

That definitively plays its part. Still even if Xamarin.iOS.dll is huge (lots of bindings) there's not a lot of variety in the API being used. I'll dig up more useful data asap

Mar 11 '21 21:03 spouliot

@eerhardt here's the references diff between the old (current) and new (dotnet) versions of the linked Xamarin.iOS.dll

--- old	2021-03-11 19:54:16.000000000 -0500
+++ new	2021-03-11 19:54:50.000000000 -0500
@@ -1,9 +1,13 @@
 A: Xamarin.iOS, Version=0.0.0.0, Culture=neutral, PublicKeyToken=84e04ff9cfb79065
-   AR: mscorlib, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e
+   AR: System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e
+      TR: System.AggregateException
+          MR: System.Collections.ObjectModel.ReadOnlyCollection`1<System.Exception> System.AggregateException::get_InnerExceptions()
+          MR: System.Void System.AggregateException::.ctor(System.Collections.Generic.IEnumerable`1<System.Exception>)
       TR: System.AppDomain
           MR: System.AppDomain System.AppDomain::get_CurrentDomain()
           MR: System.Reflection.Assembly[] System.AppDomain::GetAssemblies()
       TR: System.ArgumentException
+          MR: System.Void System.ArgumentException::.ctor(System.String,System.String)
           MR: System.Void System.ArgumentException::.ctor(System.String)
       TR: System.ArgumentNullException
           MR: System.Void System.ArgumentNullException::.ctor(System.String)
@@ -11,28 +15,35 @@
           MR: System.Void System.ArgumentOutOfRangeException::.ctor(System.String)
       TR: System.Array
           MR: !!0[] System.Array::Empty()
-      TR: System.AsyncCallback
+          MR: System.Int32 System.Array::IndexOf(!!0[],!!0)
+          MR: System.Void System.Array::Resize(!!0[]&,System.Int32)
       TR: System.Attribute
+          MR: System.Attribute System.Attribute::GetCustomAttribute(System.Reflection.MemberInfo,System.Type)
           MR: System.Void System.Attribute::.ctor()
       TR: System.AttributeTargets
       TR: System.AttributeUsageAttribute
           MR: System.Void System.AttributeUsageAttribute::.ctor(System.AttributeTargets)
       TR: System.Boolean
+      TR: System.Char
+          MR: System.Boolean System.Char::IsWhiteSpace(System.Char)
+          MR: System.String System.Char::ToString()
       TR: System.Collections.Generic.Dictionary`2
-      TR: System.Collections.Generic.EqualityComparer`1
+      TR: System.Collections.Generic.Dictionary`2/ValueCollection
+      TR: System.Collections.Generic.Dictionary`2/ValueCollection/Enumerator
       TR: System.Collections.Generic.ICollection`1
-      TR: System.Collections.Generic.IDictionary`2
       TR: System.Collections.Generic.IEnumerable`1
       TR: System.Collections.Generic.IEnumerator`1
       TR: System.Collections.Generic.IEqualityComparer`1
+      TR: System.Collections.Generic.IList`1
       TR: System.Collections.Generic.KeyValuePair`2
       TR: System.Collections.Generic.List`1
       TR: System.Collections.Generic.List`1/Enumerator
       TR: System.Collections.IDictionary
-      TR: System.Collections.IEnumerable
       TR: System.Collections.IEnumerator
           MR: System.Boolean System.Collections.IEnumerator::MoveNext()
+      TR: System.Collections.ObjectModel.ReadOnlyCollection`1
       TR: System.Delegate
+          MR: System.Reflection.MethodInfo System.Delegate::get_Method()
       TR: System.Double
           MR: System.Boolean System.Double::Equals(System.Double)
           MR: System.Boolean System.Double::Equals(System.Object)
@@ -40,14 +51,14 @@
           MR: System.Int32 System.Double::CompareTo(System.Object)
           MR: System.Int32 System.Double::GetHashCode()
           MR: System.String System.Double::ToString()
-          MR: System.String System.Double::ToString(System.IFormatProvider)
           MR: System.String System.Double::ToString(System.String,System.IFormatProvider)
-          MR: System.TypeCode System.Double::GetTypeCode()
       TR: System.Enum
-      TR: System.EventArgs
-          MR: System.EventArgs System.EventArgs::Empty
+          MR: System.Type System.Enum::GetUnderlyingType(System.Type)
+      TR: System.Environment
+          MR: System.Int32 System.Environment::get_CurrentManagedThreadId()
+          MR: System.OperatingSystem System.Environment::get_OSVersion()
+          MR: System.String System.Environment::GetEnvironmentVariable(System.String)
       TR: System.EventHandler
-          MR: System.Void System.EventHandler::Invoke(System.Object,System.EventArgs)
       TR: System.Exception
           MR: System.String System.Exception::ToString()
           MR: System.Void System.Exception::.ctor()
@@ -55,16 +66,13 @@
           MR: System.Void System.Exception::.ctor(System.String)
       TR: System.FlagsAttribute
           MR: System.Void System.FlagsAttribute::.ctor()
-      TR: System.Func`1
-      TR: System.Func`2
       TR: System.GC
           MR: System.Void System.GC::SuppressFinalize(System.Object)
-      TR: System.Globalization.CultureInfo
-          MR: System.Globalization.CultureInfo System.Globalization.CultureInfo::get_CurrentCulture()
-      TR: System.IAsyncResult
       TR: System.IComparable
       TR: System.IComparable`1
       TR: System.IConvertible
+          MR: System.Int16 System.IConvertible::ToInt16(System.IFormatProvider)
+          MR: System.Int32 System.IConvertible::ToInt32(System.IFormatProvider)
           MR: System.Int64 System.IConvertible::ToInt64(System.IFormatProvider)
           MR: System.UInt64 System.IConvertible::ToUInt64(System.IFormatProvider)
       TR: System.IDisposable
@@ -73,6 +81,7 @@
       TR: System.IFormatProvider
       TR: System.IFormattable
       TR: System.Int32
+          MR: System.String System.Int32::ToString(System.String)
       TR: System.Int64
           MR: System.Boolean System.Int64::Equals(System.Int64)
           MR: System.Boolean System.Int64::Equals(System.Object)
@@ -81,7 +90,6 @@
           MR: System.Int32 System.Int64::GetHashCode()
           MR: System.String System.Int64::ToString()
           MR: System.String System.Int64::ToString(System.String,System.IFormatProvider)
-          MR: System.TypeCode System.Int64::GetTypeCode()
       TR: System.IntPtr
           MR: System.Boolean System.IntPtr::op_Equality(System.IntPtr,System.IntPtr)
           MR: System.Boolean System.IntPtr::op_Inequality(System.IntPtr,System.IntPtr)
@@ -94,12 +102,22 @@
           MR: System.IntPtr System.IntPtr::op_Subtraction(System.IntPtr,System.Int32)
           MR: System.IntPtr System.IntPtr::Zero
           MR: System.String System.IntPtr::ToString(System.String)
+          MR: System.Void System.IntPtr::.ctor(System.Int32)
           MR: System.Void* System.IntPtr::op_Explicit(System.IntPtr)
       TR: System.InvalidCastException
           MR: System.Void System.InvalidCastException::.ctor(System.String)
+      TR: System.InvalidOperationException
+          MR: System.Void System.InvalidOperationException::.ctor()
+      TR: System.IO.FileNotFoundException
+          MR: System.String System.IO.FileNotFoundException::get_FileName()
+      TR: System.Math
+          MR: System.Int32 System.Math::Max(System.Int32,System.Int32)
       TR: System.MulticastDelegate
+      TR: System.NotImplementedException
+          MR: System.Void System.NotImplementedException::.ctor()
       TR: System.NotSupportedException
-          MR: System.Void System.NotSupportedException::.ctor()
+          MR: System.Void System.NotSupportedException::.ctor(System.String)
+      TR: System.Nullable`1
       TR: System.Object
           MR: System.Boolean System.Object::Equals(System.Object)
           MR: System.Int32 System.Object::GetHashCode()
@@ -109,26 +127,46 @@
           MR: System.Void System.Object::Finalize()
       TR: System.ObjectDisposedException
           MR: System.Void System.ObjectDisposedException::.ctor(System.String)
+      TR: System.OperatingSystem
+          MR: System.PlatformID System.OperatingSystem::get_Platform()
       TR: System.ParamArrayAttribute
           MR: System.Void System.ParamArrayAttribute::.ctor()
+      TR: System.PlatformID
+      TR: System.Reflection.AmbiguousMatchException
+          MR: System.Void System.Reflection.AmbiguousMatchException::.ctor(System.String)
       TR: System.Reflection.Assembly
           MR: System.Boolean System.Reflection.Assembly::op_Equality(System.Reflection.Assembly,System.Reflection.Assembly)
           MR: System.Boolean System.Reflection.Assembly::op_Inequality(System.Reflection.Assembly,System.Reflection.Assembly)
+          MR: System.Reflection.Assembly System.Reflection.Assembly::Load(System.Reflection.AssemblyName)
           MR: System.Reflection.AssemblyName System.Reflection.Assembly::GetName()
+          MR: System.Reflection.AssemblyName[] System.Reflection.Assembly::GetReferencedAssemblies()
           MR: System.Reflection.Module[] System.Reflection.Assembly::GetModules()
+          MR: System.String System.Reflection.Assembly::get_FullName()
+          MR: System.Type System.Reflection.Assembly::GetType(System.String,System.Boolean)
+          MR: System.Type[] System.Reflection.Assembly::GetTypes()
+      TR: System.Reflection.AssemblyInformationalVersionAttribute
+          MR: System.Void System.Reflection.AssemblyInformationalVersionAttribute::.ctor(System.String)
       TR: System.Reflection.AssemblyName
           MR: System.String System.Reflection.AssemblyName::get_Name()
+      TR: System.Reflection.Binder
       TR: System.Reflection.BindingFlags
       TR: System.Reflection.ConstructorInfo
           MR: System.Boolean System.Reflection.ConstructorInfo::op_Equality(System.Reflection.ConstructorInfo,System.Reflection.ConstructorInfo)
+          MR: System.Boolean System.Reflection.ConstructorInfo::op_Inequality(System.Reflection.ConstructorInfo,System.Reflection.ConstructorInfo)
           MR: System.Object System.Reflection.ConstructorInfo::Invoke(System.Object[])
       TR: System.Reflection.CustomAttributeExtensions
+          MR: !!0 System.Reflection.CustomAttributeExtensions::GetCustomAttribute(System.Reflection.MemberInfo,System.Boolean)
           MR: !!0 System.Reflection.CustomAttributeExtensions::GetCustomAttribute(System.Reflection.MemberInfo)
           MR: System.Collections.Generic.IEnumerable`1<!!0> System.Reflection.CustomAttributeExtensions::GetCustomAttributes(System.Reflection.MemberInfo)
+      TR: System.Reflection.DefaultMemberAttribute
+          MR: System.Void System.Reflection.DefaultMemberAttribute::.ctor(System.String)
       TR: System.Reflection.FieldInfo
+          MR: System.Boolean System.Reflection.FieldInfo::get_IsStatic()
           MR: System.Boolean System.Reflection.FieldInfo::op_Equality(System.Reflection.FieldInfo,System.Reflection.FieldInfo)
           MR: System.Object System.Reflection.FieldInfo::GetValue(System.Object)
+          MR: System.Type System.Reflection.FieldInfo::get_FieldType()
       TR: System.Reflection.ICustomAttributeProvider
+          MR: System.Boolean System.Reflection.ICustomAttributeProvider::IsDefined(System.Type,System.Boolean)
           MR: System.Object[] System.Reflection.ICustomAttributeProvider::GetCustomAttributes(System.Type,System.Boolean)
       TR: System.Reflection.InterfaceMapping
           MR: System.Reflection.MethodInfo[] System.Reflection.InterfaceMapping::InterfaceMethods
@@ -136,36 +174,61 @@
       TR: System.Reflection.MemberInfo
           MR: System.Boolean System.Reflection.MemberInfo::IsDefined(System.Type,System.Boolean)
           MR: System.Boolean System.Reflection.MemberInfo::op_Equality(System.Reflection.MemberInfo,System.Reflection.MemberInfo)
+          MR: System.Boolean System.Reflection.MemberInfo::op_Inequality(System.Reflection.MemberInfo,System.Reflection.MemberInfo)
           MR: System.Int32 System.Reflection.MemberInfo::get_MetadataToken()
+          MR: System.Object[] System.Reflection.MemberInfo::GetCustomAttributes(System.Boolean)
           MR: System.Object[] System.Reflection.MemberInfo::GetCustomAttributes(System.Type,System.Boolean)
           MR: System.String System.Reflection.MemberInfo::get_Name()
           MR: System.Type System.Reflection.MemberInfo::get_DeclaringType()
       TR: System.Reflection.MethodBase
           MR: System.Boolean System.Reflection.MethodBase::get_ContainsGenericParameters()
+          MR: System.Boolean System.Reflection.MethodBase::get_IsGenericMethod()
+          MR: System.Boolean System.Reflection.MethodBase::get_IsGenericMethodDefinition()
           MR: System.Boolean System.Reflection.MethodBase::get_IsSpecialName()
           MR: System.Boolean System.Reflection.MethodBase::get_IsStatic()
+          MR: System.Boolean System.Reflection.MethodBase::get_IsVirtual()
           MR: System.Boolean System.Reflection.MethodBase::op_Equality(System.Reflection.MethodBase,System.Reflection.MethodBase)
           MR: System.Boolean System.Reflection.MethodBase::op_Inequality(System.Reflection.MethodBase,System.Reflection.MethodBase)
           MR: System.Object System.Reflection.MethodBase::Invoke(System.Object,System.Object[])
           MR: System.Reflection.ParameterInfo[] System.Reflection.MethodBase::GetParameters()
       TR: System.Reflection.MethodInfo
           MR: System.Boolean System.Reflection.MethodInfo::op_Equality(System.Reflection.MethodInfo,System.Reflection.MethodInfo)
+          MR: System.Boolean System.Reflection.MethodInfo::op_Inequality(System.Reflection.MethodInfo,System.Reflection.MethodInfo)
           MR: System.Reflection.ICustomAttributeProvider System.Reflection.MethodInfo::get_ReturnTypeCustomAttributes()
           MR: System.Reflection.MethodInfo System.Reflection.MethodInfo::GetBaseDefinition()
+          MR: System.Type System.Reflection.MethodInfo::get_ReturnType()
       TR: System.Reflection.Module
           MR: System.Int32 System.Reflection.Module::get_MetadataToken()
           MR: System.Reflection.Assembly System.Reflection.Module::get_Assembly()
           MR: System.Reflection.MethodBase System.Reflection.Module::ResolveMethod(System.Int32)
           MR: System.Type System.Reflection.Module::ResolveType(System.Int32)
       TR: System.Reflection.ParameterInfo
+          MR: System.Boolean System.Reflection.ParameterInfo::get_IsOut()
+          MR: System.Boolean System.Reflection.ParameterInfo::IsDefined(System.Type,System.Boolean)
+          MR: System.Object[] System.Reflection.ParameterInfo::GetCustomAttributes(System.Type,System.Boolean)
+          MR: System.String System.Reflection.ParameterInfo::get_Name()
           MR: System.Type System.Reflection.ParameterInfo::get_ParameterType()
+      TR: System.Reflection.ParameterModifier
       TR: System.Reflection.PropertyInfo
+          MR: System.Boolean System.Reflection.PropertyInfo::get_CanRead()
+          MR: System.Boolean System.Reflection.PropertyInfo::get_CanWrite()
+          MR: System.Boolean System.Reflection.PropertyInfo::op_Equality(System.Reflection.PropertyInfo,System.Reflection.PropertyInfo)
           MR: System.Boolean System.Reflection.PropertyInfo::op_Inequality(System.Reflection.PropertyInfo,System.Reflection.PropertyInfo)
+          MR: System.Reflection.MethodInfo System.Reflection.PropertyInfo::get_GetMethod()
+          MR: System.Reflection.MethodInfo System.Reflection.PropertyInfo::get_SetMethod()
           MR: System.Reflection.MethodInfo System.Reflection.PropertyInfo::GetGetMethod()
+          MR: System.Reflection.MethodInfo System.Reflection.PropertyInfo::GetGetMethod(System.Boolean)
           MR: System.Reflection.MethodInfo System.Reflection.PropertyInfo::GetSetMethod()
+          MR: System.Reflection.MethodInfo System.Reflection.PropertyInfo::GetSetMethod(System.Boolean)
+          MR: System.Type System.Reflection.PropertyInfo::get_PropertyType()
+      TR: System.Reflection.TypeFilter
+          MR: System.Void System.Reflection.TypeFilter::.ctor(System.Object,System.IntPtr)
+      TR: System.Runtime.CompilerServices.CompilationRelaxationsAttribute
+          MR: System.Void System.Runtime.CompilerServices.CompilationRelaxationsAttribute::.ctor(System.Int32)
+      TR: System.Runtime.CompilerServices.CompilerGeneratedAttribute
+          MR: System.Void System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor()
       TR: System.Runtime.CompilerServices.ConditionalWeakTable`2
       TR: System.Runtime.CompilerServices.ExtensionAttribute
-          MR: System.Void System.Runtime.CompilerServices.ExtensionAttribute::.ctor()
       TR: System.Runtime.CompilerServices.InternalsVisibleToAttribute
           MR: System.Void System.Runtime.CompilerServices.InternalsVisibleToAttribute::.ctor(System.String)
       TR: System.Runtime.CompilerServices.IsVolatile
@@ -174,10 +237,12 @@
       TR: System.Runtime.CompilerServices.RuntimeCompatibilityAttribute
           MR: System.Void System.Runtime.CompilerServices.RuntimeCompatibilityAttribute::.ctor()
       TR: System.Runtime.CompilerServices.RuntimeHelpers
-          MR: System.Int32 System.Runtime.CompilerServices.RuntimeHelpers::get_OffsetToStringData()
+          MR: System.Void System.Runtime.CompilerServices.RuntimeHelpers::InitializeArray(System.Array,System.RuntimeFieldHandle)
       TR: System.Runtime.ExceptionServices.ExceptionDispatchInfo
           MR: System.Runtime.ExceptionServices.ExceptionDispatchInfo System.Runtime.ExceptionServices.ExceptionDispatchInfo::Capture(System.Exception)
           MR: System.Void System.Runtime.ExceptionServices.ExceptionDispatchInfo::Throw()
+      TR: System.Runtime.InteropServices.FieldOffsetAttribute
+          MR: System.Int32 System.Runtime.InteropServices.FieldOffsetAttribute::get_Value()
       TR: System.Runtime.InteropServices.GCHandle
           MR: System.IntPtr System.Runtime.InteropServices.GCHandle::op_Explicit(System.Runtime.InteropServices.GCHandle)
           MR: System.IntPtr System.Runtime.InteropServices.GCHandle::ToIntPtr(System.Runtime.InteropServices.GCHandle)
@@ -187,6 +252,7 @@
           MR: System.Runtime.InteropServices.GCHandle System.Runtime.InteropServices.GCHandle::FromIntPtr(System.IntPtr)
           MR: System.Void System.Runtime.InteropServices.GCHandle::Free()
       TR: System.Runtime.InteropServices.GCHandleType
+      TR: System.Runtime.InteropServices.InAttribute
       TR: System.Runtime.InteropServices.Marshal
           MR: System.Int32 System.Runtime.InteropServices.Marshal::ReadInt32(System.IntPtr)
           MR: System.Int32 System.Runtime.InteropServices.Marshal::SizeOf(System.Type)
@@ -200,14 +266,25 @@
           MR: System.Void System.Runtime.InteropServices.Marshal::Copy(System.Byte[],System.Int32,System.IntPtr,System.Int32)
           MR: System.Void System.Runtime.InteropServices.Marshal::FreeHGlobal(System.IntPtr)
           MR: System.Void System.Runtime.InteropServices.Marshal::WriteByte(System.IntPtr,System.Byte)
+          MR: System.Void System.Runtime.InteropServices.Marshal::WriteInt32(System.IntPtr,System.Int32)
+          MR: System.Void System.Runtime.InteropServices.Marshal::WriteIntPtr(System.IntPtr,System.IntPtr)
+      TR: System.Runtime.InteropServices.MarshalAsAttribute
+          MR: System.Int32 System.Runtime.InteropServices.MarshalAsAttribute::SizeConst
+          MR: System.Runtime.InteropServices.UnmanagedType System.Runtime.InteropServices.MarshalAsAttribute::get_Value()
+      TR: System.Runtime.InteropServices.UnmanagedType
+      TR: System.RuntimeFieldHandle
       TR: System.RuntimeTypeHandle
       TR: System.String
           MR: System.Boolean System.String::Equals(System.String,System.String)
           MR: System.Boolean System.String::IsNullOrEmpty(System.String)
+          MR: System.Boolean System.String::op_Equality(System.String,System.String)
           MR: System.Boolean System.String::op_Inequality(System.String,System.String)
+          MR: System.Boolean System.String::StartsWith(System.String,System.StringComparison)
           MR: System.Char System.String::get_Chars(System.Int32)
+          MR: System.Char& modreq(System.Runtime.InteropServices.InAttribute) System.String::GetPinnableReference()
           MR: System.Int32 System.String::get_Length()
           MR: System.Int32 System.String::IndexOf(System.Char)
+          MR: System.Int32 System.String::IndexOfAny(System.Char[])
           MR: System.String System.String::Concat(System.String,System.String,System.String,System.String)
           MR: System.String System.String::Concat(System.String,System.String,System.String)
           MR: System.String System.String::Concat(System.String,System.String)
@@ -217,16 +294,32 @@
           MR: System.String System.String::Format(System.String,System.Object,System.Object)
           MR: System.String System.String::Format(System.String,System.Object)
           MR: System.String System.String::Format(System.String,System.Object[])
+          MR: System.String System.String::Insert(System.Int32,System.String)
+          MR: System.String System.String::Replace(System.String,System.String)
+          MR: System.String System.String::Substring(System.Int32)
+          MR: System.String System.String::Trim()
+          MR: System.String[] System.String::Split(System.Char,System.StringSplitOptions)
+      TR: System.StringComparison
+      TR: System.StringSplitOptions
       TR: System.Text.Encoding
           MR: System.Byte[] System.Text.Encoding::GetBytes(System.String)
           MR: System.Text.Encoding System.Text.Encoding::get_UTF8()
-      TR: System.Threading._ThreadPoolWaitCallback
-          MR: System.Void System.Threading._ThreadPoolWaitCallback::SetDispatcher(System.Func`2<System.Func`1<System.Boolean>,System.Boolean>)
+      TR: System.Text.StringBuilder
+          MR: System.Text.StringBuilder System.Text.StringBuilder::Append(System.Char)
+          MR: System.Text.StringBuilder System.Text.StringBuilder::Append(System.Object)
+          MR: System.Text.StringBuilder System.Text.StringBuilder::Append(System.String)
+          MR: System.Text.StringBuilder System.Text.StringBuilder::AppendFormat(System.String,System.Object,System.Object,System.Object)
+          MR: System.Text.StringBuilder System.Text.StringBuilder::AppendFormat(System.String,System.Object,System.Object)
+          MR: System.Text.StringBuilder System.Text.StringBuilder::AppendFormat(System.String,System.Object)
+          MR: System.Void System.Text.StringBuilder::.ctor()
+          MR: System.Void System.Text.StringBuilder::.ctor(System.String,System.Int32,System.Int32,System.Int32)
       TR: System.Threading.Interlocked
           MR: System.Int32 System.Threading.Interlocked::Decrement(System.Int32&)
       TR: System.Threading.Monitor
           MR: System.Void System.Threading.Monitor::Enter(System.Object,System.Boolean&)
           MR: System.Void System.Threading.Monitor::Exit(System.Object)
+      TR: System.Threading.SendOrPostCallback
+          MR: System.Void System.Threading.SendOrPostCallback::Invoke(System.Object)
       TR: System.Threading.SynchronizationContext
           MR: System.Void System.Threading.SynchronizationContext::.ctor()
           MR: System.Void System.Threading.SynchronizationContext::SetSynchronizationContext(System.Threading.SynchronizationContext)
@@ -234,30 +327,49 @@
           MR: System.Threading.Thread System.Threading.Thread::get_CurrentThread()
       TR: System.Tuple`2
       TR: System.Type
+          MR: System.Boolean System.Type::get_ContainsGenericParameters()
+          MR: System.Boolean System.Type::get_IsAbstract()
           MR: System.Boolean System.Type::get_IsArray()
           MR: System.Boolean System.Type::get_IsByRef()
+          MR: System.Boolean System.Type::get_IsEnum()
+          MR: System.Boolean System.Type::get_IsExplicitLayout()
+          MR: System.Boolean System.Type::get_IsGenericParameter()
           MR: System.Boolean System.Type::get_IsGenericType()
+          MR: System.Boolean System.Type::get_IsGenericTypeDefinition()
           MR: System.Boolean System.Type::get_IsInterface()
+          MR: System.Boolean System.Type::get_IsNested()
           MR: System.Boolean System.Type::get_IsPointer()
+          MR: System.Boolean System.Type::get_IsValueType()
           MR: System.Boolean System.Type::IsAssignableFrom(System.Type)
           MR: System.Boolean System.Type::IsSubclassOf(System.Type)
           MR: System.Boolean System.Type::op_Equality(System.Type,System.Type)
           MR: System.Boolean System.Type::op_Inequality(System.Type,System.Type)
+          MR: System.Int32 System.Type::GetArrayRank()
           MR: System.Reflection.Assembly System.Type::get_Assembly()
           MR: System.Reflection.ConstructorInfo[] System.Type::GetConstructors(System.Reflection.BindingFlags)
           MR: System.Reflection.FieldInfo System.Type::GetField(System.String,System.Reflection.BindingFlags)
+          MR: System.Reflection.FieldInfo[] System.Type::GetFields(System.Reflection.BindingFlags)
           MR: System.Reflection.InterfaceMapping System.Type::GetInterfaceMap(System.Type)
+          MR: System.Reflection.MethodInfo System.Type::GetMethod(System.String,System.Reflection.BindingFlags,System.Reflection.Binder,System.Type[],System.Reflection.ParameterModifier[])
+          MR: System.Reflection.MethodInfo System.Type::GetMethod(System.String)
           MR: System.Reflection.MethodInfo[] System.Type::GetMethods(System.Reflection.BindingFlags)
           MR: System.Reflection.Module System.Type::get_Module()
+          MR: System.Reflection.PropertyInfo System.Type::GetProperty(System.String,System.Reflection.BindingFlags)
           MR: System.Reflection.PropertyInfo[] System.Type::GetProperties()
+          MR: System.Reflection.PropertyInfo[] System.Type::GetProperties(System.Reflection.BindingFlags)
           MR: System.String System.Type::get_AssemblyQualifiedName()
           MR: System.String System.Type::get_FullName()
+          MR: System.String System.Type::get_Namespace()
           MR: System.Type System.Type::get_BaseType()
           MR: System.Type System.Type::GetElementType()
           MR: System.Type System.Type::GetGenericTypeDefinition()
           MR: System.Type System.Type::GetTypeFromHandle(System.RuntimeTypeHandle)
+          MR: System.Type System.Type::MakeByRefType()
+          MR: System.Type System.Type::MakeGenericType(System.Type[])
+          MR: System.Type[] System.Type::FindInterfaces(System.Reflection.TypeFilter,System.Object)
+          MR: System.Type[] System.Type::GetGenericArguments()
+          MR: System.Type[] System.Type::GetGenericParameterConstraints()
           MR: System.Type[] System.Type::GetInterfaces()
-      TR: System.TypeCode
       TR: System.UInt32
       TR: System.UInt64
           MR: System.Boolean System.UInt64::Equals(System.Object)
@@ -267,26 +379,14 @@
           MR: System.Int32 System.UInt64::GetHashCode()
           MR: System.String System.UInt64::ToString()
           MR: System.String System.UInt64::ToString(System.String,System.IFormatProvider)
-          MR: System.TypeCode System.UInt64::GetTypeCode()
       TR: System.ValueType
-   AR: System, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e
-      TR: Mono.SystemDependencyProvider
-          MR: System.Void Mono.SystemDependencyProvider::Initialize()
-A: mscorlib, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e
+      TR: System.Version
+          MR: System.Boolean System.Version::op_Inequality(System.Version,System.Version)
+          MR: System.Boolean System.Version::op_LessThanOrEqual(System.Version,System.Version)
+          MR: System.Int32 System.Version::get_Build()
+          MR: System.Int32 System.Version::get_Major()
+          MR: System.Int32 System.Version::get_Minor()
+          MR: System.Void System.Version::.ctor(System.Int32,System.Int32)
+      TR: System.Void
+A: System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e
    -
-A: System, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e
-   AR: mscorlib, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e
-      TR: Mono.DependencyInjector
-          MR: System.Void Mono.DependencyInjector::Register(Mono.ISystemDependencyProvider)
-      TR: Mono.ISystemDependencyProvider
-      TR: System.Object
-          MR: System.Void System.Object::.ctor()
-      TR: System.Runtime.CompilerServices.ExtensionAttribute
-          MR: System.Void System.Runtime.CompilerServices.ExtensionAttribute::.ctor()
-      TR: System.Runtime.CompilerServices.InternalsVisibleToAttribute
-          MR: System.Void System.Runtime.CompilerServices.InternalsVisibleToAttribute::.ctor(System.String)
-      TR: System.Runtime.CompilerServices.RuntimeCompatibilityAttribute
-          MR: System.Void System.Runtime.CompilerServices.RuntimeCompatibilityAttribute::.ctor()
-      TR: System.Threading.Monitor
-          MR: System.Void System.Threading.Monitor::Enter(System.Object,System.Boolean&)
-          MR: System.Void System.Threading.Monitor::Exit(System.Object)

Mar 12 '21 00:03 spouliot

I took a quick look at the assembly last night and what I've seen is largely (still) disabled optimizations.

The dynamic registrar is not removed (missing optimization) so there's more usage (than normal) of System.Reflection API.
Several build-time only attributes are not removed (missing optimization) -> mostly metadata
UIThread checks are not removed (missing optimization) -> an extra call for some methods

Only one (dynamic registrar) would have a significant impact on what's required inside System.Private.CoreLib.dll but the recursive effect might be larger.

Update

I missed the most obvious - since I can see the IL of the dotnet version it means the mono-cil-strip was not run against the assembly (which is normally done as Full AOT is used). That's likely the biggest contributor to the extra size of the assembly.

Mar 12 '21 14:03 spouliot

Numbers from 6.0.1xx-preview3 using 6.0.100-preview.3.21202.5

Notes:

ICU is not enable (no data file included) but likely part of the binary (executable) size increase.

Application Comparer

A /Users/poupou/git/net6/p3/xamarin-macios/tests/dotnet/size-comparison/MySingleView/oldnet/bin/iPhone/Release/MySingleView.app
B /Users/poupou/git/net6/p3/xamarin-macios/tests/dotnet/size-comparison/MySingleView/dotnet/bin/iPhone/Release/net6.0-ios/ios-arm64/MySingleView.app

Directories / Files	A	B	diff	%
.//_CodeSignature
.//
embedded.mobileprovision	12,391	12,391	0	0.0%
Info.plist	1,063	1,063	0	0.0%
libmonosgen-2.0.dylib	0	6,245,360	6,245,360	-
libSystem.IO.Compression.Native.dylib	0	827,248	827,248	-
libSystem.Native.dylib	0	124,480	124,480	-
libSystem.Net.Security.Native.dylib	0	72,016	72,016	-
libSystem.Security.Cryptography.Native.Apple.dylib	0	80,992	80,992	-
libxamarin-dotnet-debug.dylib	0	627,008	627,008	-
libxamarin-dotnet.dylib	0	428,032	428,032	-
mscorlib.aotdata.arm64	297,304	0	-297,304	-100.0%
mscorlib.dll	407,552	0	-407,552	-100.0%
MySingleView	3,749,104	13,298,528	9,549,424	254.7%
MySingleView.aotdata.arm64	816	792	-24	-2.9%
MySingleView.dll	0	4,608	4,608	-
MySingleView.exe	4,608	0	-4,608	-100.0%
MySingleView.pdb	0	10,296	10,296	-
PkgInfo	8	8	0	0.0%
System.aotdata.arm64	752	0	-752	-100.0%
System.dll	4,608	0	-4,608	-100.0%
System.Private.CoreLib.aotdata.arm64	0	653,536	653,536	-
System.Private.CoreLib.dll	0	721,408	721,408	-
System.Runtime.CompilerServices.Unsafe.aotdata.arm64	0	7,232	7,232	-
System.Runtime.CompilerServices.Unsafe.dll	0	6,656	6,656	-
Xamarin.iOS.aotdata.arm64	35,720	80,912	45,192	126.5%
Xamarin.iOS.dll	56,320	159,744	103,424	183.6%

Statistics

Native subtotal	3,749,104	13,298,528	9,549,424	254.7%
Executable	3,749,104	13,298,528	9,549,424	254.7%
AOT data *.aotdata	0	0	0	-

Managed *.dll/exe	473,088	892,416	419,328	88.6%

TOTAL	4,575,507	23,370,285	18,794,778	410.8%

Apr 06 '21 20:04 spouliot

Results with the release/6.0.1xx-preview4 branch

Major changes from P3 is that it includes the ICU data file icudt.dat for globalization while removing the .dylib and .pdb.

Application Comparer

Directories / Files	Legacy	6.0.1xx-preview4	diff	%
.//_CodeSignature
.//
embedded.mobileprovision	12,391	12,391	0	0.0%
icudt.dat	0	1,713,152	1,713,152	-
Info.plist	1,076	1,076	0	0.0%
mscorlib.aotdata.arm64	297,312	0	-297,312	-100.0%
mscorlib.dll	407,552	0	-407,552	-100.0%
MySingleView	3,749,280	13,989,808	10,240,528	273.1%
MySingleView.aotdata.arm64	816	792	-24	-2.9%
MySingleView.dll	0	4,608	4,608	-
MySingleView.exe	4,608	0	-4,608	-100.0%
PkgInfo	8	8	0	0.0%
System.aotdata.arm64	752	0	-752	-100.0%
System.dll	4,608	0	-4,608	-100.0%
System.Private.CoreLib.aotdata.arm64	0	718,504	718,504	-
System.Private.CoreLib.dll	0	802,304	802,304	-
System.Runtime.aotdata.arm64	0	504	504	-
System.Runtime.dll	0	5,120	5,120	-
Xamarin.iOS.aotdata.arm64	35,720	80,272	44,552	124.7%
Xamarin.iOS.dll	56,320	157,696	101,376	180.0%

Statistics

Native subtotal	3,749,280	13,989,808	10,240,528	273.1%
Executable	3,749,280	13,989,808	10,240,528	273.1%
AOT data *.aotdata	0	0	0	-

Managed *.dll/exe	473,088	969,728	496,640	105.0%

TOTAL	4,575,704	17,491,860	12,916,156	282.3%

Apr 20 '21 21:04 spouliot

@marek-safar here's the binlog for the dotnet version. It comes from main (not P4) as this includes the latest (feature switches) changes build-dotnet.binlog.zip

Apr 23 '21 20:04 spouliot

@spouliot from the log there is still one optimization disabled (--disable-opt unusedtypechecks) which I think is worth investigating why.

Apr 27 '21 16:04 marek-safar

Another reason (beside stripping which I have working locally) for the native code to be larger might be related to the lack of the LLVM AOT backend.

if ((abi & Abi.LLVM) == Abi.LLVM)
	throw ErrorHelper.CreateError (99, $"Support for LLVM hasn't been implemented yet.");

not sure what's the status on this... it does not seems to be tracked in https://github.com/xamarin/xamarin-macios/issues/8901 @rolfbjarne @marek-safar ?

Apr 29 '21 00:04 spouliot

@spouliot from the log there is still one optimization disabled (--disable-opt unusedtypechecks) which I think is worth investigating why.

59cdbc6098

The linker will treat type checks as a constant value (false), if the type in question is not instantiated, but we're instantiating types using reflection, which the linker can't see. The result is that the CIKernel_BasicTest/CIKernel_TestFromPrograms tests in monotouch-test fail.

So here we disable this particular linker optimization.

Ref: https://github.com/mono/linker/pull/1595 Ref: https://discord.com/channels/732297728826277939/751137004007456849/776033084431925268

Apr 29 '21 00:04 spouliot

Another reason (beside stripping which I have working locally) for the native code to be larger might be related to the lack of the LLVM AOT backend.
if ((abi & Abi.LLVM) == Abi.LLVM)
	throw ErrorHelper.CreateError (99, $"Support for LLVM hasn't been implemented yet.");
not sure what's the status on this... it does not seems to be tracked in #8901 @rolfbjarne @marek-safar ?

This is basically just a TODO for our side, I'm not aware of anything the runtime team has to do here.

I've filed https://github.com/xamarin/xamarin-macios/issues/11379 to keep track of it.

Apr 29 '21 07:04 rolfbjarne

Results with the release/6.0.1xx-preview5 branch, commit ea0097c56837c34a484e06d0abdb2e658ea4556f

Highlights

Directories / Files	Legacy	preview.5	diff	%
.//_CodeSignature
.//
embedded.mobileprovision	12,391	12,391	0	0.0%
icudt.dat	0	1,713,152	1,713,152	-
Info.plist	1,073	1,073	0	0.0%
mscorlib.aotdata.arm64	297,320	0	-297,320	-100.0%
mscorlib.dll	407,552	0	-407,552	-100.0%
MySingleView	3,749,488	7,529,904	3,780,416	100.8%
MySingleView.aotdata.arm64	816	792	-24	-2.9%
MySingleView.dll	0	4,608	4,608	-
MySingleView.exe	4,608	0	-4,608	-100.0%
PkgInfo	8	8	0	0.0%
System.aotdata.arm64	752	0	-752	-100.0%
System.dll	4,608	0	-4,608	-100.0%
System.Private.CoreLib.aotdata.arm64	0	674,896	674,896	-
System.Private.CoreLib.dll	0	713,216	713,216	-
System.Runtime.aotdata.arm64	0	504	504	-
System.Runtime.dll	0	4,608	4,608	-
Xamarin.iOS.aotdata.arm64	38,464	44,784	6,320	16.4%
Xamarin.iOS.dll	57,856	73,216	15,360	26.5%

Statistics

Native subtotal	4,086,840	8,250,880	4,164,040	101.9%
Executable	3,749,488	7,529,904	3,780,416	100.8%
AOT data	337,352	720,976	383,624	113.7%

Managed *.dll/exe	474,624	795,648	321,024	67.6%

TOTAL	4,580,197	10,778,777	6,198,580	135.3%

Notes

IL stripping

This is not yet available for net6 builds. Manually using the mono-cil-strip tools hints at the expected size reduction.

Directories / Files	Legacy	preview.5	diff	%
TOTAL	4,580,197	10,459,289	5,879,092	128.4%

See more details

Globalization Impact

The above P5 table is not a perfect comparison as legacy globalization support does not, by default, support for all cultures, i.e. that requires some optional I18N.*.dll assemblies. In contrast the default net6 app supports every cultures (just like other net6 platforms).

The following numbers are when net6 "Invariant Globalization" option is used. However this is, again, not a perfect comparison. The legacy app has support for several cultures included by default.

Directories / Files	Legacy	preview.5	diff	%
TOTAL	4,580,197	8,802,021	4,221,824	92.2%

See more details

AFAICT the closest match for what legacy offered would be using icudt_EFIGS.dat (English, French, Italian, German and Spanish). This is not yet easy to configure but the following numbers are probably the closest approximation to compare, at least for the same feature set.

Directories / Files	Legacy	preview.5	diff	%
TOTAL	4,580,197	9,667,733	5,087,536	111.1%

See more details

Jun 04 '21 17:06 spouliot

JFYI there's an unexplained difference in the size of the ICU data files (https://github.com/dotnet/designs/pull/225#discussion_r647159143). Fixing that may shave off another 200kb or so.

Jun 08 '21 09:06 filipnavara

@filipnavara I noticed a decrease on main (P6) in that file size. Not sure if related to your comment or not.

Jun 08 '21 13:06 spouliot

Nope, it's still wrong (big) in today's ICU package.

Jun 08 '21 14:06 filipnavara

Nope, it's still wrong (big) in today's ICU package.

Maybe, but I do get a smaller size in main than P5

| icudt.dat | 0 | 1,636,880 | 1,636,880 | -

Still a different size, even larger, does not mean wrong, e.g. there's a issue open wrt missing calendar data.

Anyway I expect the size of those files to vary over times (reduced by optimizations and enlarged to include missing data) and would not assume any future gain (but would gladly accept them).

Jun 08 '21 16:06 spouliot

The sizes should not vary across platforms within the same ICU package. They are generated from the same data using the same filters and tools. Currently they do differ, the Android and Browser ones are identical (and smaller) and the iOS ones are tiny bit larger.

> find . -name icudt.dat | xargs ls -l
-rw-r--r--@ 1 filipnavara  staff  1512896 Jun  7 13:03 ./android-arm/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1512896 Jun  7 13:03 ./android-arm64/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1512896 Jun  7 13:03 ./android-x64/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1512896 Jun  7 13:03 ./android-x86/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1512896 Jun  7 13:03 ./browser-wasm/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1516384 Jun  7 13:03 ./ios-arm/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1713152 Jun  7 13:03 ./ios-arm64/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1713152 Jun  7 13:03 ./iossimulator-arm64/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1713152 Jun  7 13:03 ./iossimulator-x64/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1713152 Jun  7 13:03 ./iossimulator-x86/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1713152 Jun  7 13:03 ./maccatalyst-arm64/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1713152 Jun  7 13:03 ./maccatalyst-x64/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1713152 Jun  7 13:03 ./tvos-arm64/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1713152 Jun  7 13:03 ./tvossimulator-arm64/native/lib/icudt.dat
-rw-r--r--@ 1 filipnavara  staff  1713152 Jun  7 13:03 ./tvossimulator-x64/native/lib/icudt.dat

Jun 08 '21 16:06 filipnavara

Another reason (beside stripping which I have working locally) for the native code to be larger might be related to the lack of the LLVM AOT backend.
if ((abi & Abi.LLVM) == Abi.LLVM)
	throw ErrorHelper.CreateError (99, $"Support for LLVM hasn't been implemented yet.");

I built System.Private.CoreLib.dll by hand using a Mono LLVM AOT cross-compiler but there isn't very much of a size difference compared to mini's native codegen. And I haven't yet replicated by hand exactly what we're doing to generate a final executable.

But we're failing to constant-fold some runtime type checks (ThrowHelper.ThrowForUnsupportedNumericVectorBaseType for example) in both modes and I think fixing this would recover at least 300kb of executable code in __text. We're also generating "impossible" function instantiations (like generating T_REF instantiations for functions with type-level parameters that have struct constraints). We're also compiling a lot more code--post-link System.Private.CoreLib.dll yields about 23366 native Mach-O symbols while mscorlib.dll from old Mono produces ~11246.

Jun 25 '21 04:06 imhameed

Here's the output of "Bloaty McBloatface" run on the netcore non-LLVM SingleView app as of 732c27afb37feb17f1ca161d55d4f92ea115c929:

https://gist.githubusercontent.com/imhameed/f7c1cf3e4061c659413a428a57187b12/raw/772babda28a1bbad644b41dbab76134ea43b1fd1/bloaty-2021-06-30-732c27afb37feb17f1ca161d55d4f92ea115c929.txt

A tsv is also available at https://gist.github.com/imhameed/f7c1cf3e4061c659413a428a57187b12

Jul 08 '21 13:07 imhameed

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.NET 6: SingleView app size

Test case

Known Issues

Historical

App sizes

Xamarin.iOS

.NET 6

Assembly sizes

Xamarin.iOS

.NET 6

Application Comparer

Application Comparer

Update

Application Comparer

Application Comparer

Highlights

Notes

IL stripping

Globalization Impact

xamarin-macios xamarin-macios copied to clipboard

.NET 6: SingleView app size

Test case

Known Issues

Historical

App sizes

Xamarin.iOS

.NET 6

Assembly sizes

Xamarin.iOS

.NET 6

Application Comparer

Application Comparer

Update

Application Comparer

Application Comparer

Highlights

Notes

IL stripping

Globalization Impact

xamarin-macios
xamarin-macios copied to clipboard