>> The biggest problem with this technique, from an optimization perspective, is that it creates an irreducible control-flow graph. The technique is considered

>> The biggest problem with this technique, from an optimization perspective, is that it creates an irreducible control-flow graph. The technique is considered obsolete with todays compilers specifically because they can do loop optimizations like this without writing strange C code. OTOH you never know what those wacky compiler guys are going to do. For example, it seems GCC hasn't been doing any vectorization on x86-64 with standard -O2 even though the ISA has supported SSE2 as a minimum from day one. This is being fixed (to some extent) in the next release.