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One Line, Three Tricks: Unpacking a Quake 1 Gem
- ferguess_k 2y agoMy question is: is it going to produce more efficient assembly code when compiled? Guess I'll have to run it through Godbolt.
- sepisoad 2y agoi put together something in godbolt and here is the result: https://godbolt.org/z/sbzPT33nq https://godbolt.org/z/sbzPT33nq “quake” version uses “lea" to pre-increment pointers before storing values. “normal” version uses “add" after storing values. The “lea" instruction is often faster because it performs an addition in a single cycle without modifying flags, whereas “add" may introduce a dependency. “quake” version might have a slight edge due to better pipeline efficiency. “lea" is often preferred over “add" in performance-critical code because it is a single-cycle instruction on modern x86 CPUs.