You are correct: the way ComputeSharp works is that there is a Roslyn source generator that rewrites the shaders at build time from C# to HLSL (mapping types, methods, intrinsics, etc.), then shaders are compiled and cached at runtime (this gives the library some additional flexibility, like being able to have shader metaprogramming too, ie. capturing delegates in a shader to compose them dynamically) and then dispatched on the GPU.
ILGPU basically does more things to just make your code well optimized from what I can see (with its full JIT compiler, like you mentioned), whereas ComputeSharp is more about letting you write a "C#-ified HLSL shader" that is then run as is. So you could say it's less forgiving but might give you more control (as in, you can basically port GLSL/HLSL shaders directly to C# and run them in ComputeSharp with almost no code changes (see https://twitter.com/SergioPedri/status/1363869460793335811 or https://twitter.com/SergioPedri/status/1364210592760872960).
Also as I mentioned before, which is one of the key differences (which is cool, I love that the two libraries have a very different structure and key features!), ComputeSharp is tightly coupled with DX12 APIs, which gives it some extra features like textures and automatic pixel format conversion, and makes it very easy to interop with other DX stuff (eg. to use a swap chain panel to render a shader to a window, like I do in one of my samples).
Goes without saying, I think ILGPU is a really cool project! I will definitely need to find the time to have a more in depth look at it, I'm sure there's plenty of cool things I could learn from that.
ILGPU basically does more things to just make your code well optimized from what I can see (with its full JIT compiler, like you mentioned), whereas ComputeSharp is more about letting you write a "C#-ified HLSL shader" that is then run as is. So you could say it's less forgiving but might give you more control (as in, you can basically port GLSL/HLSL shaders directly to C# and run them in ComputeSharp with almost no code changes (see https://twitter.com/SergioPedri/status/1363869460793335811 or https://twitter.com/SergioPedri/status/1364210592760872960).
Also as I mentioned before, which is one of the key differences (which is cool, I love that the two libraries have a very different structure and key features!), ComputeSharp is tightly coupled with DX12 APIs, which gives it some extra features like textures and automatic pixel format conversion, and makes it very easy to interop with other DX stuff (eg. to use a swap chain panel to render a shader to a window, like I do in one of my samples).
Goes without saying, I think ILGPU is a really cool project! I will definitely need to find the time to have a more in depth look at it, I'm sure there's plenty of cool things I could learn from that.
Cheers!