Again: not a single study with a benchmark, just an anecdote that actually means the opposite of what is intended. The authors of Bzip had to write non-idiomatic code to prevent UB "optimization" from breaking their code, and this results in compiled code that may or may not be slower. Tip: fewer assembly instructions does not always mean faster execution in a pipelined processor. In fact, compiling with -fwrap probably would generate better code.