3 months ago
- Unsafe pointer arithmetic can be used in Go to eliminate bound checks that the compiler cannot remove, provided the programmer can prove they are unnecessary.
- Bound checks elimination (BCE) reduces instructions and branches, improving performance by lowering cache misses, register pressure, and wasted cycles.
- Go's compiler adds bound checks to prevent out-of-range slice accesses, which can be identified using the -gcflags='-d=ssa/check_bce/debug=1' flag.
- Conventional BCE methods include hinting the compiler by accessing bounds first, but unsafe techniques are needed when the compiler cannot infer safety.
- An unsafe alternative to binary.LittleEndian.Uint32, using unsafe.SliceData and unsafe.Add, eliminates all bound checks and significantly boosts performance in benchmarks.