Re:Translating Quake 3 into Rust
by jashmatthews on Tuesday January 07, 2020 @06:06PM
(#21986224)
> C very much defines pointers as aliasing by default.
This is actually a huge issue for the CRuby JIT which generates C from the VM bytecode. Alias analysis on the generated C code, which is full of indirection, is basically useless and severely restricts the possible optimizations.
c2rust has to be careful not to "restrict" pointers which can in fact alias.
> But last I heard Rust wasn't taking advantage of this due to issues with LLVM.
That's correct: https://github.com/rust-lang/rust/issues/54878
> The same benefits should also be achievable in C with pragmas.
I don't know that any compiler provides a noalias-all pragma. I don't know that it would be very sane either since C very much defines pointers as aliasing by default. Plus you wouldn't have any way to revert this behaviour and mark pointers as aliasing.