[rurban]

Try -O3 with -march-native, and you'll get tons of warnings, trivial to fix. Just the register allocator name overflow not, this would need an internal name length policy decision.

[MaxLeiter]

The only project I know using QBE is Hare. Does anyone know some others?

[garritfra → MaxLeiter]

There's a "Users" page on the homepage, that lists projects using QBE:

https://c9x.me/compile/users.html