When running a sum loop over an array in Rust, I noticed a huge performance drop when CAPACITY >= 240. CAPACITY = 239 is about 80 times faster. Is there special compilation optimization Rust is doing for “short” arrays? Compiled with rustc -C opt-level=3. use std::time::Instant; const CAPACITY: usize = 240; const IN_LOOPS: usize = … Read more
As far as I know, reference/pointer aliasing can hinder the compiler’s ability to generate optimized code, since they must ensure the generated binary behaves correctly in the case where the two references/pointers indeed alias. For instance, in the following C code, void adds(int *a, int *b) { *a += *b; *a += *b; } when … Read more
I know that an “undefined behaviour” in C++ can pretty much allow the compiler to do anything it wants. However, I had a crash that surprised me, as I assumed that the code was safe enough. In this case, the real problem happened only on a specific platform using a specific compiler, and only if … Read more
