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neonsunset

You've never actually verified this claim, have you? Next time - please do it.

- structs, with auto, sequential and explicit layout, with complex SROA and promotion handling

- stack-allocated buffers, unsafe fixed and inline arrays, even managed objects can have their layout configured

- monomorphized struct generics compiled the same way they do in Rust

- raw and byref pointers with pointer arithmetic

- portable and platform-specific SIMD, platform-specific intrinsics

- zero-cost interop which enables calls into malloc/free at the cost of C/C++ (you do not actually need this - there is a managed reimplementation of mimalloc which is fully competitive with the original)

- static linking with native dependencies when using nativeaot

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In C, I can just write the whole program without calling malloc. I write my own allocator tuned for my programs behavior, I even have multiple allocators if needed. I just have a lot more control available. If you can't do this in a language, you can't claim its performance is close to C. Performance is about control.

It's as if you didn't bother reading my previous comment. Incredible.

You keep ignoring the point. Show me how can I write a program in C# that works with a fixed size memory region, lets say 512KB. It should not do any dynamic memory allocation.

Here's a library that does this in C in case you are wondering: https://github.com/rxi/microui.

Sigh.

  // Please, just allocate a normal array instead, there is no benefit to this if it lives throughout the whole application lifetime
  var bytes = (stackalloc byte[512 * 1024]);

  // or, but, please, at least use a span instead of C nonsense of tracking offsets by hand
  // it's not 1980 anymore
  var ptr = stackalloc byte[512 * 1024]; // byte*

  // or
  [InlineArray(256 * 1024)]
  struct CommandList { byte _; }

  var commands = new CommandList();

  // or
  unsafe struct State
  {
    public fixed byte CommandList[256 * 1024];
  }

Whichever you like the most, they do have somewhat different implications - stackalloc is C alloca while struct-based definitions have the exact same meaning as in C.

To avoid running into stack space limitations, you can place a fixed buffer or any of these large arrays into a static field. It gets a fixed static offset in the memory.

C# goes much further and also provides zero-cost abstractions via struct generics with interface constraints. Or without - you can also apply pattern matching against a generic T struct and it will be zero-cost and evaluated at compilation (be it with RyuJIT or ILC (IL AOT Compiler)).

Nice, thanks a lot for sharing the knowledge.

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