[Tor3]

I have no idea what you mean by 'no support for modern standards'. It's a modern compiler for modern C (and the newest versions are compatible with code written for modern gcc, with a flag). The only thing about it is it has its own syntax for flags, which aren't exactly difficult, and they're well documented.

It produces better code than gcc in many cases. Which is exactly what you would expect for a compiler written specifically for IBM by IBM. Lots of fine-tuning options for the Power architectures.

You say you have a few AIX machines - which one, and which OS version, and which compiler versions? I'm on Power7 and Power8, with AIX 7.1 Don't look at AIX 4/5.