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Cranelift - the compiler toolchain being discussed in this post (previously known as Cretonne) - is actually completely written in Rust, being developed (obviou

Cranelift - the compiler toolchain being discussed in this post (previously known as Cretonne) - is actually completely written in Rust, being developed (obviously) by Rust programmers, that are members of the Rust community. Its development started at Mozilla, which still employs some of its developers to work on it full-time. So.. the claim that the Rust community is not big enough to achieve this is wrong, since they have already done it.. The reason they are doing it, is that LLVM is not fine: it is super _super_ slow. People want Rust to compile instantaneously, and are willing to pay people full time to work on that. D, for example, compiles much faster than C and C++, and does this by having their own backend for unoptimized builds. I don't know how big the D community is, so I can't compare its size to the Rust community, but they did it, and it payed of for them big time, so I don't see why it wouldn't pay off for Rust as well.

int_19h 7y ago
DMD inherited the backend from DMC++, which was the end of a long line of optimizing C and C++ compilers going back over a decade before the earliest D alphas.
jfkebwjsbx 7y ago
> LLVM is not fine: it is super _super_ slow Source? LLVM is fast for what it does. What people usually complain about is rustc being slow overall, not the LLVM passes.
- chc 7y ago
  This is true to some degree — Rust does more work than most programming languages, and that work will always take some time — but the Cranelift backend is also measurably faster than the LLVM one.
- kibwen 7y ago
  > What people usually complain about is rustc being slow overall, not the LLVM passes. The LLVM phases are usually the dominating factor in Rust compile times (the other big single contender is the linking phase). However, when the Rust developers point this out, they are also careful to mention that this may be due to the rustc frontend generating suboptimal IR as input to LLVM; we can both acknowledge that LLVM is often the bottleneck for Rust compilation while also not framing it as a failure on LLVM's part (though at the same time it is uncontroversial to state that LLVM does err on the side of superior codegen versus minimal compilation time, hence the niche that alternative compilers like Cranelift seek to fill).
bluGill 7y ago
I didn't claim rust isn't big enough to do it. (that may well be true given the large effort that went into llvm over many years to make it a good optimizer - this is a different debate though and I'm not sure if it is true) What I said was rust is better off focusing on problems that are not solved well by other people. A fast modern web browser (with whatever features is lacking) for example.

int_19h 7y ago

DMD inherited the backend from DMC++, which was the end of a long line of optimizing C and C++ compilers going back over a decade before the earliest D alphas.

jfkebwjsbx 7y ago

> LLVM is not fine: it is super _super_ slow Source? LLVM is fast for what it does. What people usually complain about is rustc being slow overall, not the LLVM passes.

chc 7y ago
This is true to some degree — Rust does more work than most programming languages, and that work will always take some time — but the Cranelift backend is also measurably faster than the LLVM one.
kibwen 7y ago
> What people usually complain about is rustc being slow overall, not the LLVM passes. The LLVM phases are usually the dominating factor in Rust compile times (the other big single contender is the linking phase). However, when the Rust developers point this out, they are also careful to mention that this may be due to the rustc frontend generating suboptimal IR as input to LLVM; we can both acknowledge that LLVM is often the bottleneck for Rust compilation while also not framing it as a failure on LLVM's part (though at the same time it is uncontroversial to state that LLVM does err on the side of superior codegen versus minimal compilation time, hence the niche that alternative compilers like Cranelift seek to fill).

bluGill 7y ago

I didn't claim rust isn't big enough to do it. (that may well be true given the large effort that went into llvm over many years to make it a good optimizer - this is a different debate though and I'm not sure if it is true) What I said was rust is better off focusing on problems that are not solved well by other people. A fast modern web browser (with whatever features is lacking) for example.