Zig self hosted compiler is now capable of building itself

Re:Zig self hosted compiler is now capable of building itself by elcritch on Sunday April 17, 2022 @03:26AM (#31059159)

Perhaps, though nothing there that's not been available for a while. To be fair Zig has integrated some of these features well.

* MultiArrayList is convenient and easy to do in Rust, D, Nim. Odin seems built around it. * Arbitrary bit-size integers seem more gimmicky than anything and similar to struct bitfields in other languages (except Rust oddly). Most compilers don't even pack uint8/uint16's for performance reasons. * Special purpose allocators are a bit more interesting. Still they don't provide actual memory safety AFAICT and can have fragmentation and performance penalties.

It'll be interesting to see larger Zig code bases emerge in different fields and see how the memory footprint compares in practice.

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Re:Zig self hosted compiler is now capable of building itself by bonzini on Sunday April 17, 2022 @03:44AM (#31059244)

What? 8- and 16-bit are never 32-bit aligned nor sized.

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Re:Zig self hosted compiler is now capable of building itself by elcritch on Sunday April 17, 2022 @06:16AM (#31059815)

To clarify I meant comparing how int8/int16's are packed in structs vs struct bitfields. Can't recall about the stack rules. Here's more discussion:

http://www.catb.org/esr/structure-packing/

https://github.com/Twon/Alignment/blob/master/docs/alignment...

Also ARM for example doesn't have 8/16 bit registers so int8 or int16 will use a 32bit register:

https://stackoverflow.com/a/23716920

Curiosity got to me, perhaps Zig had improved significantly. So I compared the first benchmark I found (kostya/benchmarks/bf) with Zig with Nim. For the smaller input (bench.b) Zig did run with ~22% less RAM (about 20kB less).

However, for the larger input (mandel.b) Nim+ARC used ~33% less RAM in safe mode: Nim 2.163mb -d:release; Zig 2.884mb -O ReleaseSafe; Zig 2.687mb -O ReleaseFast. The Nim requires 0.5mb less ram and the code is ~40% shorter. I don't have time to try out the Rust or Go versions though.

edit: grammar

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Re:Zig self hosted compiler is now capable of building itself by dralley on Sunday April 17, 2022 @02:59PM (#31063287)

Are the two using the exact same algorithm?

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Re:Zig self hosted compiler is now capable of building itself by elcritch on Sunday April 17, 2022 @05:33PM (#31064688)

Yes, as far as I can tell [1]. It's a simple Tape algorithm. Neither had any crazy SIMD, threads, no custom containers, etc. They use almost the same function names (and look the same as the Go version too). I used `time -l` https://stackoverflow.com/a/30124747 for memory usage.

Note I ran the benchmarks locally (MacBook Air M1) because the reported benchmark uses the older (default) Nim GC while I only use Nim+ARC. I also had to fix the Zig code and it took a few tries to get the signed/unsigned int conversions working. I tried tweaking flags for both a bit as well to see how stable they were. Zig's memory usage was pretty constant. Nim had a small speed vs memory tradeoff that could be tweak-able, but the defaults used the least memory.

Overall I'd expect exact memory usage by language(s) to vary some by benchmark and one random benchmark isn't conclusive. Still I didn't find anything to indicate Zig is clearly better than other new generation languages. Manual memory management might actually be worse than letting a compiler manage it in some cases.

1: https://github.com/kostya/benchmarks/tree/master/brainfuck

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