To be fair, the backend in the early GCC 3.x series was just kind of stupid sometimes. Even now I find strange if cheap and harmless heisengremlins in GCC-produced x86 code (like MOV R, S; MOV S, R; MOV R, S) from time to time, while the Clang output, even if not always good, is at least reasonable. This is not to diss the GCC team—the effort required to port a whole compiler to a completely new IR with a completely different organizing principle while keeping it working most of that time boggles the mind, frankly. But the result does occasionally behave in weird ways.