[saagarjha]

> As an example, consider the following JavaScript code…The generated bytecode for this JavaScript (under V8) is pretty bloated.

I don't think this is a good comparison. You're telling the compiler for Zig and Rust to pick something very modern to target, while I don't think V8 does the same. Optimizing JITs do actually know how to vectorize if the circumstances permit it.

Also, fwiw, most modern languages will do the same optimization you do with strings. Here's C++ for example: https://godbolt.org/z/TM5qdbTqh

[vanderZwan]

In general it's a bit of an apples to fruit salad comparison, albeit one that is appropriate to highlight the different use-cases of JS and Zig. The Zig example uses an array with a known type of fixed size, the JS code is "generic" at run time (x and y can be any object). Which, fair enough, is something you'd have to pay the cost for in JS. Ironically though in this particular example one actually would be able to do much better when it comes to communicating type information to the JIT: ensure that you always call this function with Float64Arrays of equal size, and the JIT will know this and produce a faster loop (not vectorized, but still a lot better).

Now, one rarely uses typed arrays in practice because they're pretty heavy to initialize so only worth it if one allocates a large typed array one once and reuses them a lot aster that, so again, fair enough! One other detail does annoy me a little bit: the article says the example JS code is pretty bloated, but I bet that a big part of that is that the JS JIT can't guarantee that 65536 equals the length of the two arrays so will likely insert a guard. But nobody would write a for loop that way anyway, they'd write it as i < x.length, for which the JIT does optimize at least one array check away. I admit that this is nitpicking though.

[Retro_Dev]

You can change the `target` in those two linked godbolt examples for Rust and Zig to an older CPU. I'm sorry I didn't think about the limitations of the JS target for that example. As for your link, It's a good example of what clang can do for C++ - although I think that the generated assembly may be sub-par, even if you factor in zig compiling for a specific CPU here. I would be very interested to see a C++ port of https://github.com/RetroDev256/comptime_suffix_automaton though. It is a use of comptime that can't be cleanly guessed by a C++ compiler.

[saagarjha]

I just skimmed your code but I think C++ can probably constexpr its way through. I understand that's a little unfair though because C++ is one of the only other languages with a serious focus on compile-time evaluation.