Publish AOT increases the assembly file size!

[mahdighorbanpourptw]

Comparing the published file using AOT and without AOT (but singleFile), I see a major difference in the size. In this bare example the difference is just about 3 MB, but in our production app is much more!
Publish SingleFile without AOT: 17MB
Publish with AOT: 38 MB
What could be the reason for this and how I can achieve the same level of size?

To Reproduce

dotnew new console -n TestAot
Add the follwoing to the csproj file:

<RuntimeIdentifiers>linux-x64</RuntimeIdentifiers>
<PublishTrimmed>true</PublishTrimmed>
<TrimMode>partial</TrimMode>
<PublishAot>true</PublishAot>

Publish the project using the folowing command:
dotnet publish --configuration release -r linux-x64 --self-contained true /p:EnableCompressionInSingleFile=true -o ./linux-x64

Further technical details

.NET SDK:
Version: 8.0.200
Commit: 438cab6a9d
Workload version: 8.0.200-manifests.cdf2cc8e

Runtime Environment:
OS Name: ubuntu
OS Version: 22.04
OS Platform: Linux
RID: linux-x64
Base Path: /usr/share/dotnet/sdk/8.0.200/

.NET workloads installed:
There are no installed workloads to display.

Host:
Version: 8.0.2
Architecture: x64
Commit: 1381d5ebd2

.NET SDKs installed:
6.0.406 [/usr/share/dotnet/sdk]
8.0.200 [/usr/share/dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 6.0.14 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.2 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.14 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.2 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
None

Environment variables:
DOTNET_ROOT [/usr/lib/dotnet]

global.json file:
Not found

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https://aka.ms/dotnet/download

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[MichalStrehovsky]

You are comparing a compressed single file executable (EnableCompressionInSingleFile) with an uncompressed AOT compiled executable. If you want to have a meaningful comparison, you should also compress the AOT version: e.g. with PublishAotCompressed.

Also, if you want good size, you need to remove <TrimMode>partial</TrimMode> from the project. AOT can only efficiently generate outputs with full trimming. Partial trimming inhibits many optimizations and you'll never get good size outputs with it.

[mahdighorbanpourptw]

You are comparing a compressed single file executable (EnableCompressionInSingleFile) with an uncompressed AOT compiled executable. If you want to have a meaningful comparison, you should also compress the AOT version: e.g. with PublishAotCompressed.

Also, if you want good size, you need to remove <TrimMode>partial</TrimMode> from the project. AOT can only efficiently generate outputs with full trimming. Partial trimming inhibits many optimizations and you'll never get good size outputs with it.

Thanks a lot @MichalStrehovsky
I tried it and it works! How come dotnet team don't have an official solution for this?

[MichalStrehovsky]

I tried it and it works! How come dotnet team don't have an official solution for this?

The compression makes startup time worse and uses more memory. Startup time and memory use are the main reasons why someone would choose native AOT in the first place. Compression negates all that and doesn't make much sense in general. There might be special circumstance where it makes sense, but third party tools can be used to do that and an official solution wouldn't be any different from them. We have no plans to add official solution for this.