[rstuart4133]

> The GitHub issue discussion is directly about these concerns and discuss whether bounds checks may fail early, whether intermediate writes are observable after catch_unwind and whether panic behavior must be preserved.

No argument about the point of the issue. But this is a discussion about the relative efficiency of C, C++ and Rust. My point is there is a way in Rust to say "I don't care about observable writes, hoist the bounds check out of the loop", so that the efficiency is the same.

Admittedly, it's not part of the language definition. You're relying on intimate knowledge of how the optimiser works. In fact, you are probably pasting the code into godbolt, and looking at the assembler produced. But if you care about cycles that much, that's true for all three languages.